JP6520488B2 - Method of manufacturing hollow tube having U-shaped bent portion and manufacturing apparatus of hollow tube having U-shaped curved portion - Google Patents

Description

  The present invention relates to hydroforming hollow tubes used in heat exchangers, automobile parts, etc., particularly hollow tubes having a U-shaped bent portion (U-shaped bent portion). It relates to a method for applying and manufacturing, and an apparatus used for its implementation.

  In heat exchangers, automobile parts, building interior materials / exterior materials, or chemical plants, etc., use a hollow pipe with a U-shaped bent part as a part of a straight pipe (straight pipe) There is. Here, the U-shaped bent portion (U-shaped bent portion) is a protrusion between two or more straight pipe portions in a direction forming a predetermined angle with the axial direction of each straight pipe portion, and It can be rephrased that the projecting portion is a U-shaped portion. As a typical example, as shown in (a) or (b) of FIG. 33, between two straight pipe sections 1A, 1B having a common axis O, their straight pipe sections 1A, 1B are There is a hollow tube 5 having a U-shaped bend 3 which projects in a direction perpendicular to the axial direction. Here, in the case of the example of (a) of FIG. 33, a first bend 7A bent substantially at right angles from one straight pipe portion 1A toward the U-shaped bend 3 and a substantially right angle in the U-shaped bend 3 There are a total of four bends: second and third bends 7B and 7C, and fourth bend 7D that bends substantially at right angles from U-shaped bend 3 to the other straight pipe 1B. doing. Further, in the case of the example of (b) of FIG. 33, a first bend 9A bent substantially at right angles from one straight pipe portion 1A toward the U-shaped bend 3 and a predetermined curvature in the U-shaped bend 3 Has a total of three bends: a second bend 9B that bends by approximately 180 °, and a third bend 9C that bends approximately at right angles from the U-shaped bend 3 to the other straight pipe portion 1B. ing.

  For producing a hollow tube having such a U-shaped bent portion (hereinafter simply referred to as a U-shaped bent tube), in particular a U-shaped bent tube composed of a metal pipe such as a steel pipe, a copper pipe or an aluminum pipe As a conventional method, there is a method in which bending is repeated a plurality of times in a straight pipe by a shear bending press. Also, as a similar method, there is a method of bending a straight pipe using a so-called pipe bender. When forming a U-shaped bent pipe by bending a straight pipe, it is usual to previously fill the hollow pipe with a filler such as sand so that the hollow pipe is not crushed by bending.

  Also known is a method of manufacturing a U-shaped bent pipe directly from molten metal by casting or die casting. In this case, the core is used to form the hollow portion.

In order to obtain a U-shaped bent pipe as shown in (a) or (b) of FIG. 33 by a method of bending a straight pipe using a shear bending press machine or a pipe bender as described above, plural times It is necessary to apply a bending process, which inevitably lowers productivity. In addition, it is necessary to be filled with a filler such as sand in advance, and the operation for the filling and the removal of the filler after processing also becomes an impediment factor of the improvement in productivity.
Furthermore, in these bending methods, a U-shaped curved tube having a small distance S between parallel parts in the U-shaped curved portion 3, in particular, 180 in the U-shaped curved portion 3 as shown in FIG. It was extremely difficult to obtain a U-shaped bent tube in which the radius of curvature r of the bent portion 9B of the bending, that is, the top of the U-shaped portion, is small.

  On the other hand, it is difficult to manufacture a thin U-curved tube by casting or die-casting, and it is difficult to produce a thin U-curved tube by the method of manufacturing a U-curved tube directly from molten metal, and productivity is low. There is a problem that requires time and effort.

By the way, the hydroforming which used the hydraulic pressure is being prevailed recently.
Hydroforming uses a hollow tubular material (raw material pipe) such as a steel pipe, stainless steel pipe, or aluminum pipe as a molding material, sets the raw material pipe in the cavity of the mold, and It is filled with a pressurizing liquid, and high-pressure liquid pressure is applied to the material tube, and at the same time, the material tube is compressed (axially pushed) from both ends of the material tube along its axial direction, This is a processing method of forming into a shape conforming to the shape, and since a hollow member having a complicated shape can be integrally formed, it has recently been applied to the manufacture of various parts such as automobiles.
And the method of manufacturing the hollow tube which has a bending part is proposed by patent document 1, patent document 2 grade | etc., Etc., utilizing such hydroforming.

  The method proposed in Patent Document 1 uses hydroforming to produce a hollow tube having a bend and an increased diameter of the bend, ie, a bend with a bulge. The method of Patent Document 1 will be described with reference to (a) to (c) of FIG.

  In (a) of FIG. 34, the mold 10 is constituted by an upper mold 10A and a lower mold 10B which can be separated up and down. A downward convex portion 12 is formed on the upper mold 10A, and an upward concave portion 13 is formed on the lower mold 10B corresponding to the convex portion 12 of the upper mold 10A. On the other hand, the tube ends 14A and 14B at both ends of the material tube 14 are sealed by the tube end sealing members 15A and 15B (see (c) in FIG. 34). These tube end sealing members 15A, 15B not only seal the space in the material tube 11 but also squeeze the pressing member for compressing (axially pressing) the material tube 14 along its axial direction. At least one of them is connected to a shaft pushing drive such as a hydraulic cylinder (not shown). Further, in these pipe end sealing members 15A, 15B, a flow path 17 for introducing a pressurizing liquid, for example, water, into the material pipe 11 or discharging residual air in the material pipe 11 is formed. Ru.

  And as shown to (a) of FIG. 34, the raw material pipe | tube 14 is arrange | positioned on the lower mold | type 10B in the state (mold open | release state) which separated the upper mold | type 10A and lower mold | type 10B. , 14B are supported by the material tube end supporting portions 16A and 16B of the lower die 10B, and then the upper die 10A is lowered as shown in (b) of FIG. It bends and deforms along the convex part 12 of this. Further, as shown in (c) of FIG. 34, the pressurizing liquid is introduced (arrow) in the raw material pipe 14, the inside of the raw material pipe 14 is filled with the pressurizing liquid, and then the raw material pipe 14 is filled with the pressurizing liquid. Pressurize to high pressure. At the same time, a load (axial pushing force) along the axial direction is applied to the material pipe 14 by the pipe end sealing members 15A and 15B which also serve as the axial pushing members. As a result, the bent portion of the material tube 14 is expanded in diameter, and a bent tube with a bulging portion is obtained.

  Although the method disclosed in such Patent Document 1 applies hydroforming for sure, it can be said that hydroforming using hydraulic pressure is only for diameter expansion processing in the latter stage, and bending processing in the former stage. In itself, the plastic deformation by physically pressing the convex portion 12 of the upper die 10A against the material pipe is used, and the hydraulic pressure is not used. In such a method, as in the case of using a shear bending press or a pipe bender as described above, a U-shaped curved tube having a small distance S between parallel parts in a U-shaped curved portion, particularly in FIG. As shown in b), it was extremely difficult to obtain a U-shaped bent tube in which the radius of curvature r of the bending portion 9B at 180 ° bending in the U-shaped bent portion 3 is small.

  In addition, Patent Document 2 discloses a method of manufacturing a metal pipe having two or more bends and having an irregular cross section such as a square as a cross-sectional shape of the bend using hydroforming. However, the method of this patent document 2 also utilizes bending by physical pressing of the upper mold in the bending portion forming process of the former stage, and only uses hydraulic pressure in the cross-sectional shape forming process of the latter stage. Therefore, as in the method disclosed in Patent Document 1, the radius of curvature r of the U-curved tube having a small distance S between the parallel portions in the U-curved portion, in particular the 180 ° -bent bend 9B in the U-curved portion 3 It was extremely difficult to obtain a small U-shaped bend.

JP 2003-103314 A Unexamined-Japanese-Patent No. 2004-50279

  The present invention has been made against the background described above, and can efficiently produce a hollow tube having a U-shaped bent portion with high productivity, and moreover, the distance between parallel portions and the top in the U-shaped bent portion. It is an object of the present invention to provide a method by which a hollow tube with a small radius of curvature can be easily obtained and, at the same time, to provide an apparatus most suitable for carrying out the method.

  The inventor conducted various experiments and studies to solve the above-mentioned problems, and as a result, when bending the material pipe, the hydroforming was elaborated by devising the mold structure for hydroforming. The inventors have found that it is possible to easily form a U-shaped curved portion, particularly a U-shaped curved portion having a small distance between parallel parts and a small radius of curvature, by utilizing the axial pressing force and the application of hydraulic pressure.

Accordingly, the subject matter of the present invention is as follows.
That is, a method of manufacturing a hollow tube having a U-shaped bent portion according to the basic aspect (first aspect) of the present invention is
Between two or more straight pipe section, around the producing hollow tube having a U-shaped bend portion projecting with respect to the axial direction of the straight pipe section in a direction forming a predetermined angle,
A groove is formed between the mold member forming the upper mold and the mold member forming the lower mold, into which a hollow tube-shaped material tube is inserted, and at least one of the upper and lower mold members is formed of At least one recess is formed continuous with the space in the groove and recessed toward the inside of the other mold member, and at least on the side of the other mold member, the space in the groove passes through the space in the groove Using a mold provided with at least one push-out member that can move back and forth
A raw material pipe is disposed in the groove, and both ends of the raw material pipe are sealed by a pipe end sealing member which doubles as an axial pushing member, and liquid pressure is applied to the inner space of the raw material pipe. The pressing member is advanced from the side of the other mold member toward the inside of the recess while pressing in the direction along the axis from the side (i.e. while pressing), and the middle portion in the longitudinal direction of the material tube is A method of manufacturing a hollow tube having a U- shaped bend, wherein the hollow tube has a U- shaped bend which is pushed into the recess and thereby forms a U-shaped bend of the material tube in the recess ,
After stopping the advancing of the push-up member, the U-curved portion in the concave portion is raised by increasing the hydraulic pressure applied to the inner space of the raw material pipe while continuing the pressurization in the axial direction of the raw material pipe. It shape | molds in the shape along the inner surface of a recessed part, It is characterized by the above-mentioned.

In the manufacturing method according to the first aspect, while the hydraulic pressure is applied to the material tube, the pushing member is advanced toward the inside of the recess while axially pressing the material tube, and the middle portion in the longitudinal direction of the material tube Can be efficiently formed in the middle portion of the material tube by a simple process of pushing into the recess. The distance between the parallel portions of the U-curved portion of the hollow tube obtained or the curvature radius of the top of the U-curved portion is the thickness of the projecting member (thickness in the direction along the axial direction of the material tube) or the projecting member Since it is determined by the radius of curvature of the tip, by setting the thickness of the projecting member or the radius of curvature of the projecting member to a suitably small value, the distance between the parallel portions of the U-shaped curved portion or the top of the U-shaped curved portion A hollow tube having a small radius of curvature can be easily obtained.
Furthermore, in the manufacturing method of the first aspect, the outer surface shape of the U-shaped bent portion can be formed into a desired shape with high accuracy.

Further, according to the second aspect of the present invention, there is provided a method of producing a hollow tube having a U-shaped bent portion,
In manufacturing a hollow tube having a U-shaped bent portion protruding in a direction forming a predetermined angle with the axial direction of the straight pipe portion between two or more straight pipe portions,
A groove is formed between the mold member forming the upper mold and the mold member forming the lower mold, into which a hollow tube-shaped material tube is inserted, and at least one of the upper and lower mold members is formed of At least one recess is formed continuous with the space in the groove and recessed toward the inside of the other mold member, and at least on the side of the other mold member, the space in the groove passes through the space in the groove Using a mold provided with at least one push-out member that can move back and forth
A raw material pipe is disposed in the groove, and both ends of the raw material pipe are sealed by a pipe end sealing member which doubles as an axial pushing member, and liquid pressure is applied to the inner space of the raw material pipe. The pressing member is advanced from the side of the other mold member toward the inside of the recess while pressing in the direction along the axis from the above, and the longitudinal middle portion of the material tube is pushed into the recess, A method of manufacturing a hollow tube having a U-shaped bent portion, wherein the U-shaped bent portion of the material tube is formed in the concave portion by the
In the middle of the process of advancing the extruding member and pushing the middle portion in the longitudinal direction of the material tube into the recess, the advancing member is stopped from advancing, and the extruding member is subsequently retracted, and after the advancing member stops advancing, An intermediate portion of the material pipe is pushed into the recess by only the hydraulic pressure applied to the inner space of the material pipe and the pressing force applied to the material pipe along the axial direction from both ends thereof .

In the manufacturing method of the second aspect as described above, similarly to the spine imaging method of the first aspect, the U-shaped bent portion can be efficiently formed in the middle portion of the material pipe by a simple process, Furthermore, in the second half of the process of pushing the middle portion of the raw material pipe into the recess, the protruding member does not intervene inside the U-shaped bent portion, so the radius of curvature of the top of the U-shaped bent portion It is possible to obtain a hollow tube with or near zero .

The manufacturing method of a hollow tube with a third aspect U-by bending portions of the present invention is the manufacturing method of the prior SL second aspect, after stopping the advance of the push-up member, the axial direction of the material pipe The U-shaped bent portion in the recess is formed into a shape along the inner surface of the recess by increasing the hydraulic pressure applied to the inner space of the material tube while continuing the pressure application. It is.

Furthermore, in the method of manufacturing a hollow tube having a U-shaped bent portion according to the fourth aspect of the present invention, in the manufacturing method of any one of the first to third aspects, the one mold is further used as the mold. As a member, using a counter member that can move back and forth toward the other mold member in the recess, the protrusion member is advanced to push the middle portion of the material tube into the recess, and at the same time, the material The counter member is retracted while bringing the outer surface of the middle portion of the tube into contact with the tip end surface of the counter member.

  In the manufacturing method according to the fourth aspect, bending is performed while the top surface of the bent portion of the material pipe is in contact with the tip end surface of the counter member in the process of pressing the middle portion of the material pipe into the recess and bending deformation. Because it is deformed, it is effective that the diameter of the material tube is locally expanded, or the material tube is deformed to an abnormal shape, and the situation where the original correct bending shape can not be obtained occurs. Can be prevented.

  Further, in the method of manufacturing a hollow tube having a U-shaped bent portion according to the fifth aspect of the present invention, in the manufacturing method of the fourth aspect, after stopping advancing of the push-up member and retraction of the counter member The U-curved portion is shaped along the tip surface of the counter member and the inner surface of the recess by increasing the fluid pressure applied to the inner space of the material tube while continuing the axial pressurization of the tube. Molding.

According to the manufacturing method of the fifth aspect, as in the manufacturing method of the first aspect, the outer surface shape of the U-shaped bent portion can be formed into a desired shape with high accuracy.

  In the method of manufacturing a hollow tube having a U-shaped bent portion according to the sixth aspect of the present invention, in the method according to any one of the first to fifth aspects, the upper and lower mold members are used as the mold. A space in the groove is formed in one mold member that is continuous with the space in the groove and recessed toward the inside of the other mold member, and at least on the side of the other mold member. Using a die provided with a single projecting member capable of advancing and retreating into the recess through the above.

  According to the manufacturing method of the sixth aspect as described above, it is possible to obtain a hollow tube in which one U-shaped bent portion is formed in the middle portion of the material tube.

  In the method of manufacturing a hollow tube having a U-shaped bent portion according to the seventh aspect of the present invention, in the method according to any one of the first to fifth aspects, the upper and lower mold members are used as the mold. Two or more recesses which are continuous with the space in the groove and recessed toward the inside of the other mold member are formed in one mold member at intervals in the lengthwise direction of the groove, and the other mold is formed. A member is characterized by using a mold provided with two or more projecting members capable of advancing and retreating into the respective recesses through spaces in the groove corresponding to the two or more recesses. is there.

  In the manufacturing method of the seventh aspect as described above, it is possible to simultaneously form a U-shaped bent portion at two or more places separated in the length direction of the material pipe.

In the method of producing a hollow tube having a U-shaped bent portion according to the eighth aspect of the present invention, the method according to any of the first to fifth aspects is provided.
As the mold, one or more first projecting members are disposed on the other mold member at predetermined intervals in the lengthwise direction of the groove, and one or more second members are disposed on the one mold member. A protruding member disposed at a position shifted by a predetermined distance in the longitudinal direction of the groove with respect to the position of the first protruding member, and the one mold member corresponds to the first protruding member A first recess is formed, and a second recess corresponding to the second projecting member is formed on the other mold member,
A raw material pipe is disposed in the groove, and both ends of the raw material pipe are sealed by a pipe end sealing member which doubles as an axial pushing member, and liquid pressure is applied to the inner space of the raw material pipe. And pressing the first projecting member from the side of the other mold member while pressing in the direction along the axis of the tube, and pushing the middle portion in the longitudinal direction of the material tube into the first recess, Then, from the side of the one mold member, the second projecting member is advanced to push the middle portion in the longitudinal direction of the material pipe into the second recess, thereby the middle portion in the longitudinal direction of the material pipe Forming two or more U-shaped bent portions which are continuously bent in opposite directions.

  In the manufacturing method of the eighth aspect, a hollow tube having two or more U-shaped bent portions alternately and continuously bent in opposite directions in the longitudinal middle portion is efficiently processed by a simple process. Can be obtained.

In the method of manufacturing a hollow tube having a U-shaped bent portion according to a ninth aspect of the present invention, in the manufacturing method of the eighth aspect, at least one of the mold members further contains Using a counter member that can move back and forth toward the other mold member in
The at least one projecting member is advanced to push the middle portion of the material tube into the recess, and at the same time the counter member is retracted while bringing the outer surface of the middle portion of the pressed material tube into contact with the tip end surface of the counter member It is characterized in that

  In the manufacturing method of the ninth aspect, the middle part in the longitudinal direction has two or more U-shaped bent portions alternately bent continuously in opposite directions, and the manufacturing method of the fourth aspect Similarly, since the counter member is used, the original correct bending shape can be easily obtained without causing the local diameter expansion or the occurrence of abnormal deformation.

  In the method of manufacturing a hollow tube having a U-shaped bent portion according to the tenth aspect of the present invention, in the manufacturing method of any one of the eighth and ninth aspects, the other mold member is used as the mold. And two first projecting members are disposed at predetermined intervals in the lengthwise direction of the groove, and one second projecting member is disposed on the one mold member of the two first projecting members. A first recess is provided at an intermediate position and corresponding to the first projecting member is formed in the one mold member, and the other mold member corresponds to the second projecting member. It is characterized in that three U-shaped bent portions which are continuously bent in the opposite direction are formed at an intermediate portion in the longitudinal direction of the raw material pipe, using the one in which the second concave portion is formed.

  In the manufacturing method of the tenth aspect as described above, a hollow tube having three U-shaped bent portions alternately and continuously bent in opposite directions in an intermediate portion in the longitudinal direction, that is, a substantially W-shaped bent portion Having a hollow tube can be efficiently obtained by a simple process.

  In the method of manufacturing a hollow tube having a U-shaped bent portion according to the eleventh aspect of the present invention, the method according to any one of the first to tenth aspects is characterized in that one or more of the predetermined portions in the middle portion of the material pipe After forming the U-bent portion of the material, one or more steps of forming one or more U-bent portions at another location in the middle portion of the material tube by the same method are performed one or more times. It is characterized in that a hollow tube having a bent portion is manufactured.

  Furthermore, according to a method of producing a hollow tube having a U-shaped bent portion according to a twelfth aspect of the present invention, the method according to any one of the first to tenth aspects comprises Forming one or more other U-shaped bends in the same way in the middle part of the U-shaped bend in one or more times after forming the U-shaped bend of It is characterized in that a hollow tube having a bent portion is manufactured.

On the other hand, the thirteenth to fifteenth aspects of the present invention are directed to an apparatus for manufacturing a hollow tube having a U-shaped bent portion.

That is, the apparatus for producing a hollow tube having a U-shaped bent portion according to the thirteenth aspect of the present invention is
An apparatus for manufacturing a hollow tube having a U-shaped bent portion projecting in a direction forming a predetermined angle with the axial direction of a straight pipe portion between two or more straight pipe portions,
A mold comprising a mold member constituting an upper mold and a mold member constituting a lower mold ;
A tube end sealing member which is removable from both ends of the hollow tube and has a flow path;
Mechanical pressing means for pressing and driving the tube end sealing member;
Equipped with
And a groove is formed between the two mold members into which a hollow tubular material tube is inserted, and at least one mold member of the two mold members is continuous with the space in the groove and the other is At least one recess which is recessed toward the inside of the mold member, and at least on the other side of the mold member, at least one projecting member capable of advancing and retracting into the recess through a space in the groove Is provided ,
The at least one projecting member is controlled to be advanced and retracted by the advancing and retracting driving means, and after the advancing and retracting driving means stops the advancement of the pushing-up member, the axial pressurization of the material tube by the mechanical pressurizing means is continued It is characterized in that it is configured to increase the hydraulic pressure applied to the inner space of the material pipe through the flow path of the pipe end sealing member while keeping the same .
The apparatus for producing a hollow tube having a U-shaped bent portion according to the fourteenth aspect of the present invention is
An apparatus for manufacturing a hollow tube having a U-shaped bent portion projecting in a direction forming a predetermined angle with the axial direction of a straight pipe portion between two or more straight pipe portions,
A mold comprising a mold member constituting an upper mold and a mold member constituting a lower mold;
A tube end sealing member which is removable from both ends of the hollow tube and has a flow path;
Mechanical pressing means for pressing and driving the tube end sealing member;
Equipped with
And a groove is formed between the two mold members into which a hollow tubular material tube is inserted, and at least one mold member of the two mold members is continuous with the space in the groove and the other is At least one recess which is recessed toward the inside of the mold member, and at least on the other side of the mold member, at least one projecting member capable of advancing and retracting into the recess through a space in the groove Is provided,
The at least one projecting member is controlled by advancing and retracting drive means, and the advancing and retracting drive means drives the advancing and retracting in the middle of the process of advancing the projecting member and pushing the middle portion in the longitudinal direction of the material tube into the recess. The means stops the advancing of the protruding member, and subsequently retracts the protruding member, and after stopping the advancing of the protruding member, the liquid applied to the inner space of the material pipe through the flow path of the pipe end sealing member The apparatus is characterized in that the middle portion of the material tube is pushed into the recess only by the pressure and the pressure force applied to the material tube from the both ends in the axial direction by the mechanical pressure means. It is.

In the apparatus for manufacturing a hollow tube having a U-shaped bent portion according to the fifteenth aspect of the present invention, in the apparatus for manufacturing the thirteenth or fourteenth aspect, the one mold member of the mold includes the inside of the recess. In the above, a counter member capable of advancing and retreating toward the other mold member is provided.

  According to the present invention, a hollow tube having a U-shaped bent portion can be efficiently manufactured with high productivity, and a hollow tube having a small distance between parallel parts and a top radius of curvature at the U-shaped bent portion can be obtained. It can be easily obtained.

It is a longitudinal front view of a device for carrying out a first embodiment of a method of manufacturing a hollow tube having a U-shaped bend according to the present invention. It is a vertical side view in the II-II line in FIG. It is a vertical side view in the III-III line in FIG. It is a cross-sectional top view in the IV-IV line in FIG. It is a schematic longitudinal front view which shows in a step-wise the condition which implements 1st Embodiment of this invention method using the apparatus shown in FIGS. 1-4. FIG. 1 is a perspective view showing an example of a hollow tube having a U-shaped bend manufactured according to a first embodiment of the method of the present invention. It is a typical longitudinal elevation front view showing the situation where the 2nd embodiment of the present invention method is carried out in steps. FIG. 6 is a perspective view of an example of a hollow tube having a U-shaped bend manufactured according to a second embodiment of the method of the present invention. It is a longitudinal front view of the apparatus for enforcing 3rd Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. It is a vertical side view by the XX in FIG. It is a schematic longitudinal front view which shows in steps the situation which implements 3rd Embodiment of this invention method using the apparatus shown in FIG. 9, FIG. It is a longitudinal front view of the apparatus for enforcing 4th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. It is a vertical side view in the XIII-XIII line in FIG. It is a vertical side view in the XIV-XIV line in FIG. It is a schematic longitudinal front view which shows in a step-by-step the condition which implements 4th Embodiment of this invention using the apparatus shown in FIGS. 12-14. FIG. 7 is a perspective view of an example of a hollow tube with a U-shaped bend manufactured according to a fourth embodiment of the method of the invention. It is a longitudinal front view of the apparatus for enforcing 5th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. FIG. 18 is a schematic vertical cross-sectional front view stepwise showing the situation in which the fifth embodiment of the method of the present invention is practiced using the device shown in FIG. 17; It is a perspective view which shows an example of the hollow tube which has a U-shaped bending part manufactured by 6th Embodiment of the manufacturing method of the hollow tube which has a U-shaped bending part of this invention. It is a longitudinal front view of the apparatus for enforcing 6th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. It is a typical longitudinal cross section front view showing the situation where the 6th embodiment of a manufacturing method of a hollow tube which has a U-shaped curve part of the present invention is carried out in steps. It is a perspective view which shows an example of the hollow tube which has a U-shaped bending part manufactured by 7th Embodiment of the manufacturing method of the hollow tube which has a U-shaped bending part of this invention. It is a longitudinal front view of the apparatus for enforcing 7th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. It is a typical longitudinal cross section front view showing the situation where the 7th embodiment of a manufacturing method of a hollow tube which has a U-shaped curve part of the present invention is carried out in steps. It is a longitudinal front view of the apparatus for enforcing 8th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. It is a longitudinal front view of the apparatus for enforcing 9th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. It is a longitudinal front view of the apparatus for enforcing 10th Embodiment of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. FIG. 21 is a schematic solution view showing in stages the situation of carrying out the eleventh embodiment of the method of manufacturing a hollow tube having a U-shaped bend portion of the present invention. It is a longitudinal cross-sectional view which expands and shows the metal mold | die and the part of an ejection member as another example of the manufacturing method of the hollow tube which has U-shaped bending part of this invention. FIG. 30 is a cross-sectional plan view taken along line XXX-XXX in FIG. As another example of the manufacturing method of the hollow tube which has a U-shaped bending part of this invention, it is a vertical side view which expands and shows the metal mold | die and the part of an ejection member. FIG. 32 is a cross-sectional plan view taken along line XXXII-XXXII of FIG. It is an approximate solution front view showing two examples of a hollow tube which has a U-shaped bent part which becomes a manufacturing object by the present invention. It is a schematic diagram showing gradually an example of the conventional method for manufacturing a hollow tube which has a bent part applying hydroforming.

  Next, the present invention will be described in detail.

  1 to 4 show an example of a main part of an apparatus configuration for implementing the method of manufacturing a hollow tube having a U-shaped bent portion according to the first embodiment of the present invention, in particular an example of a mold part. FIG. 5 shows stepwise the method of manufacturing the hollow tube having the U-shaped bend in the first embodiment, and FIG. 6 shows the middle of the U-shaped bend manufactured according to the first embodiment. An example of an open pipe is shown. 1 to 4 show a state where the material pipe 37 is disposed at a required position of the mold 31 and clamped, but in a state before the start of processing.

  In FIGS. 1 to 4, the mold 31 is constituted by a mold member 33A constituting an upper mold and a mold member 33B constituting a lower mold, and these mold members 33A and 33B are mold clamping not shown. It is configured to be clamped by means. The material of the mold members 33A and 33B constituting the mold 31 is not particularly limited, and may be made of FCD 250, S50C, SKD11 or the like as in a normal hydroforming mold. In the following description, the mold member 33A constituting the upper mold is referred to as the upper mold member 33A, and the mold member 33B constituting the lower mold is referred to as the lower mold member 33B.

  The upper surface of the lower mold member 33B is formed to be flat as a whole in the present embodiment, and the upper surface of the lower mold member 33B has a horizontal half groove (lower mold groove) 35B having a semicircular cross section. It is formed upward along the direction. In the lower surface of the upper mold member 33A, a half groove (upper mold groove) 35A having a semicircular cross section is directed downward along the horizontal direction corresponding to the half groove (lower mold groove) 35B of the lower mold member 33B. Is formed. Then, in the clamped state, the lower mold groove 35B and the upper mold groove 35A form a groove 35 having a circular cross section as a whole. The groove 35 is for accommodating a hollow material tube 37 to which the manufacturing method of the present invention is applied. Therefore, the maximum diameter of the lower mold groove 35B and the upper mold groove 35A (that is, the inner diameter of the groove 35) is determined to be equal to or slightly larger than the outer diameter R of the material tube 37.

  Here, in the vicinity of both ends of the groove portion 35 (upper mold groove 35A, lower mold groove 35B) in the upper mold member 33A and lower mold member 33B, a tube end support portion for supporting the both ends 37A and 37B of the material tube 37 43A and 43B. The tube end support portions 43A and 43B are located near both ends of the material tube 37 (more precisely, both ends 37A and 37B of the material tube 37 and the subsequent tube end sealing members 45A and 45B) in a clamped state. But is configured to support the material tube 37 so as to allow movement along the length direction of the material tube 37. The tube end sealing members 45A, 45B are for sealing the space in the material tube 37, and further pressurize the material tube 37 along its axial direction from its both end sides toward the intermediate portion (shaft It also serves as an axial pushing member for pushing. Then, a liquid such as water for applying a hydraulic pressure is introduced into the material pipe 37, and residual air is discharged (air is removed) from the material pipe 37 to the pipe end sealing members 45A, 45B. One or more flow paths 47A, 47B are formed along the axial direction.

  Further, the upper mold member 33A of the mold 31 is formed with a recess 39 which is continuous with the space in the upper mold groove 35A and is recessed upward (inside the upper mold member 33A). As shown in FIG. 1, the recess 39 is such that the cross section along the length direction of the upper mold groove 35A (and hence the length direction of the material tube 37) has a substantially rectangular shape (therefore an inverted U shape) The cross section perpendicular to the longitudinal direction of the upper mold groove 35A (that is, the length direction of the material tube 37) is made as shown in FIG. It is configured to be recessed upward with a width W1 substantially the same as the maximum width (therefore, the maximum width of the groove 35). Here, the width W2 of the recess 39 in the direction parallel to the longitudinal direction of the upper mold groove 35A, that is, the distance W2 between the two inner side surfaces 39A and 39B orthogonal to the longitudinal direction of the upper mold groove 35A The dimension which is the same as or slightly larger than the dimension which exceeds twice the outside diameter R of the raw material tube 37 and usually the thickness T of the protrusion member 41 described later It is appropriate to set it to 1.0 times to 1.2 times of [R × 2 + T]. The depth D of the recess 39 (the distance from the open end of the recess 39 to the inner bottom surface 39A) D may be determined according to the height of the U-shaped bent portion to be obtained.

Further, the lower mold member 33B is provided with a projecting member 41 at a position corresponding to the center of the recess 39 of the upper mold member 33A. The projecting member 41 is formed in a long plate shape or a rod shape along the vertical direction, and in a vertical plane orthogonal to the length direction of the groove portion 35 by the advancing and retracting driving means 42 such as a fluid pressure cylinder or the like. It is configured to be able to move up and down. And this protrusion member 41 is made so that the cross section (cross section along the length direction of the groove part 35) of the upper end 41A may curve in convex shape smoothly. Here, the thickness T (the thickness in the direction along the longitudinal direction of the groove 35) of the protrusion member 41 is not particularly limited, but the thickness T is a time when forming a U-shaped bend in the material tube 37 as described later. Since it corresponds to the spacing (space; see FIG. 6) S between the parallel portions of the U-shape, it may be determined according to the space S of the U-curved portion to be finally formed. In the case of the present embodiment, in order to make the space S smaller than the outer diameter of the material tube 37, the thickness T of the protruding member 41 is set smaller than the outer diameter of the material tube 37 (therefore smaller than the maximum diameter of the groove 35). doing. Further, it is desirable that the protruding member 41 has a tip (upper end in the illustrated example) 41A as a smooth convex surface (convex curved surface). The desirable radius of curvature of the tip 41A varies depending on the material, hardness, outer diameter and thickness of the material tube 37, but the outer diameter is about 21.7 to 114.3 mm and the thickness is 1.2 to 5.0 mm In the case where a general carbon steel tube for general use is used, it is desirable that the radius of curvature of the tip end 41A of the protruding member 41 be 3.0 mm to 10.0 mm. Furthermore, the material of the protruding member 41 is not particularly limited, but normally, the material may be made of the same material as the mold 31, for example, FCD 250, S50C, SKD1 or the like.
In the initial state (at the time of non-operation), the protruding member 41 is positioned such that its tip (upper end in the illustrated example) 41A is at the bottom of the lower mold groove 35B of the lower mold member 33B or slightly lower than that. doing.

Next, a method for forming a U-shaped bent portion in the material tube 37 will be described with reference to FIGS. 5 (a) to 5 (g) using the apparatus shown in FIGS.
The material of the material tube 37 is not particularly limited as long as it is a material that can be cold or warm plastic working, for example, carbon steel, stainless steel, copper or copper alloy, aluminum or aluminum alloy, titanium or A titanium alloy etc. can be applied.

  Tube end sealing members 45A and 45B, which also function as axial pressing members, are attached in advance to both end portions (tube end portions 37A and 37B) of the material tube 37. Then, as shown in FIG. 5A, the material tube 37 is placed on the lower mold member 33B so that the lower half of the middle portion 37C is positioned in the lower mold groove 35B of the lower mold member 33B. . Further, the upper mold member 33A is lowered, and the upper half portion of the intermediate portion of the material pipe 37 is inserted into the upper mold groove 35A of the upper mold member 33A, and the mold is clamped. The clamped state is shown in FIG. 5 (b).

  In the clamped state, both end portions 37A and 37B of the material tube 37 are supported between the upper mold member 33A and the lower mold member 33B in a mode in which movement in the axial direction is permitted. The intermediate portion of the raw material tube 37 is in a state of being inserted into the groove portion 35 formed of the upper mold groove 35A and the lower mold groove 35B. At this stage, the projecting member 41 is in a state in which the tip end thereof has not been projected into the groove 35 yet. In addition, normally, at this stage, the material pipe 37 is filled with a liquid such as water for applying a hydraulic pressure. At this time, in order to prevent air from remaining in the material tube 37, the liquid is filled while performing air removal. In some cases, of course, the liquid may be filled in the material tube 37 before clamping.

  Next, as shown in FIG. 5C, fluid pressure is applied to the inside of the material tube 37 through the flow paths 47A and 47B of the tube end sealing member 45, and fluid pressure not shown for the tube end sealing members 45A and 45B. The pressure is driven (i.e., axially pressed) along the axial direction from both sides by mechanical pressing means such as a cylinder, and at the same time the ejection member 41 is advanced upward, and the material tube 37 is pushed by the tip of the ejection member 41. Push up the middle part of. As a result, bending of the middle portion of the material tube 37 in the direction of projecting upward in the recess 39 is started. That is, the bending deformation portion 37D starts to be formed. Since the fluid pressure is applied to the inside of the material tube 37, bending deformation is started without crushing.

  In this manner, if the advancing of the protruding member 41 is continued while applying the hydraulic pressure and pushing the shaft, as shown in FIG. 5D, the middle portion of the material pipe 37 becomes an inverted U-shape. It is pushed into the recess 39 while being deformed. Then, after the upper portion of the deformed portion (U-shaped bent portion) 37D contacts the inner bottom surface 39C of the recess 39 as shown in FIG. 5 (e), if the fluid pressure is further increased, as shown in FIG. 5 (f) The deformation portion is formed into a shape along which the bending deformation portion 37D substantially follows the entire inner surface of the recess 39.

  Thereafter, the application of the fluid pressure is stopped according to a conventional method, and the axial pressing force is released, the ejection member 41 is returned (retracted) to the original position, and the mold 31 is opened. Before and after that, the pressurizing liquid in the material tube 37 is discharged, the material tube 37 is taken out from the mold 31, and the tube end sealing members 45A and 45B are removed from the material tube 37, a series of processing processes (U The manufacturing process of the hollow tube having the bent portion is completed (see FIG. 5 (g)).

An example of the hollow tube 5 thus finished according to the present embodiment is shown in FIG.
As shown in FIG. 6, this hollow tube 5 is disposed between two straight tube portions 1A, 1B having a common axis O in a direction perpendicular to the axial direction of the straight tube portions 1A, 1B. It has a protruding U-shaped bend 3. Here, the cross-sectional shape of the U-shaped bent portion 3 is determined by the inner surface shape of the recess 39 and the outer surface shape of the projecting member 41. In the case of the present embodiment, the cross section is formed so as to have a substantially rectangular shape, but the present invention is not limited to this. As will be described later, the inner surface shape of the recess 39 and the outer surface shape of the projecting member 41 It is possible to shape to have different cross-sectional shapes by changing.

  The rising speed (advance speed) when raising the extruding member 41 varies depending on the material, hardness, and dimensions (outer diameter and thickness) of the material pipe 37, but both sides of the material pipe 37 It is desirable to be equal to the axial movement speed (axial pushing speed) of The axial pressing speed is not particularly limited, and the optimum speed varies depending on the material, hardness, and dimensions (outer diameter and thickness) of the material tube 37, but the outer diameter is about 21.7 to 114.3 mm. In the case where a general structural carbon steel pipe having a thickness of about 1.2 to 5.0 mm is targeted, it is preferable that the axial pressing speed be set to about 1.0 to 10.0 mm / sec. The axial pressing force and the hydraulic pressure may be determined in consideration of the rising speed of the projecting member 41, but the axial pressing force is usually about 10 kN to 3000 kN, and the hydraulic pressure is preferably about 10 MPa to 200 MPa.

  In the first embodiment described above, as shown in (b) to (f) of FIG. 5, the protruding member 41 is until the upper surface of the bent portion of the middle portion of the material tube 37 contacts the inner bottom surface 39C of the recess 39. May be advanced into the recess 39, but in some cases, the advancement of the ejection member 41 may be stopped halfway and the ejection member 41 may be subsequently retracted. The example in that case is shown to FIG.7 (a)-(d) as 2nd Embodiment.

  In this case, as shown in FIGS. 7 (a) and 7 (b), while applying the hydraulic pressure and pushing the shaft, the projecting member 41 is advanced to slightly project the tip toward the recess 39, thereby the material tube After giving a slight bending deformation to the middle portion of 37, the advancing of the ejection member 41 is stopped while continuing the application of hydraulic pressure and axial pushing, and the ejection member 41 is continuously retracted as shown in FIG. 7 (c). , And continue to apply the fluid pressure and push the shaft. That is, the projecting member 41 is pulled out from the initially formed bent portion 37D, and the application of fluid pressure and axial pressing are continued as it is. In this way, the bending portion formed by the initial projection advances to a state of 180 ° bending or a state close to that by the axial pressing force, and the bending portion is pushed upward in the recess 39. Then, the deformation continues until the upper surface of the bent portion 37D in the 180 ° bend or near state contacts the inner bottom surface 39C of the recess 39, and the shape conforms to the inner surface of the recess. A bent portion of a letter shape is formed. In other words, if bending deformation is triggered by the initial protrusion (if initiated), by continuing axial pressing and hydraulic pressure application, bending at or near 180 ° along the inner surface of the recess 39 is finally achieved. Can form a U-shaped part.

  An example of the hollow tube 5 obtained in this manner is shown in FIG. In this hollow tube 5, the space S between parallel parts in the U-shaped bend 3 is zero or close to it, in other words, the radius of curvature inside the bend of the U-shaped bend 3 is zero or close to it . In the case of the second embodiment, the width W2 (see FIG. 1) of the recess 39 in the direction parallel to the longitudinal direction of the upper mold groove 35A, that is, two of the two orthogonal to the longitudinal direction of the upper mold groove 35A. It is desirable to set the distance W2 between the side surfaces 39A and 39B relatively smaller than in the case of the first embodiment. Specifically, in view of the relationship between the outer diameter R of the raw material pipe 37 and the thickness T of the protruding member 41, it is appropriate to set it to about 1.0 times to 1.2 times [R × 2 + T].

FIGS. 9 and 10 show the mold parts of the apparatus used in the third embodiment of the present invention, and FIGS. 11 (a) to (d) show the method of the third embodiment using the same. In a step-by-step process, 9 and 10 show a state where the material pipe 37 is disposed at a required position of the mold 31 and clamped, but in a state before the start of processing.
Furthermore, in FIGS. 9 and 10, the same elements as those of the apparatus used in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and the details thereof will be omitted.

  In FIGS. 9 and 10, for example, a thick plate-like counter member 49 is disposed in the recess 39 of the upper mold member 33A. The counter member 49 has a shape similar to that of the horizontal cross section of the recess 39 as the shape of the horizontal cross section, and from the size of the horizontal cross section of the recess 39 so as to be vertically movable (liftable) in the recess 39 Even the dimensions are slightly smaller. The lower surface (tip surface) 49A of the counter member 49 is a substantially horizontal plane. The counter member 49 is configured to be movable up and down in the recess 39 by a second advancing and retracting drive unit 51 such as a fluid pressure cylinder.

  In the method according to the third embodiment, as shown in FIG. 11A, the projecting member 41 is in the retracted state, and the counter member 49 is in the stage before the start of processing only when the mold clamping is performed. The lower surface 49A is advanced (lowered) so as to be in contact with the upper surface of the material pipe 37. Then, as shown in FIGS. 11 (b) to 11 (c), simultaneously the advancing member 41 is advanced (lifted), the counter member 49 is retracted (lifted) at the same speed as the advancing speed of the pushing member 41. Thus, the middle portion of the material tube 37 is bent and deformed while the upper surface thereof is in contact with the lower surface 49A of the counter member 49. That is, since there is no extra space above the bending portion during the progress of bending deformation, the diameter of the material pipe locally expands or deforms into an abnormal shape, and the original correct bending is performed. It is possible to effectively prevent the occurrence of a situation where the shape can not be obtained.

12 to 14 show a main part of an apparatus configuration for implementing the method of manufacturing a hollow tube having a U-shaped bent portion according to a fourth embodiment of the present invention, in particular an example of a mold portion, 15 sequentially shows a method of manufacturing a hollow tube having a U-shaped bend in the fourth embodiment, and FIG. 16 shows a middle of the U-shaped bend manufactured according to the fourth embodiment. An example of an open pipe is shown. FIGS. 12 to 14 show the material pipe 37 at a required position of the mold 31 and clamped (but before the start of processing).
In addition, in FIGS. 12-14, the same code | symbol is attached | subjected about the element same as the apparatus used for 1st Embodiment shown to FIGS. 1-4, and the detail is abbreviate | omitted.

  In FIGS. 12 to 14, the upper die member 33A is provided with a first recess (hereinafter referred to as an upper die recess) 53A, and the lower die member 33B is provided with a second recess (hereinafter referred to as the upper die recess). Is referred to as a lower mold recess) 53B is formed.

Similar to the recess 39 (see FIGS. 1 to 3) in the first embodiment, the upper die recess 53A forms a continuous space above the upper die groove 35A, and the overall shape thereof Are formed in a substantially rectangular shape. The width of the upper mold recess 33A (the length in the longitudinal direction of the groove 35; therefore, the length in the axial direction of the material tube 37) W2 is slightly more than four times the outer diameter R of the material tube 37 More precisely, more precisely, it is equal to four times the outer diameter R of the material tube 37 plus the total thickness of the first projecting member 55A and the two second projecting members 55B ₁ and 55B ₂ described later. [R × 4 + T × 3] or so, if it is assumed that the dimensions of the or more slightly larger members, ie, the thicknesses of the first ejection member 55A and the two second ejection members 55B ₁ and 55B ₂ are T, respectively. It is set to a slightly larger degree. Further, the distance W1 (see FIG. 13) before and after the upper die recess 53A is set to be equal to or slightly larger than the outer diameter R of the material tube 37.

The lower die recess 53B forms a space continuing from the lower die groove 35B below, and the overall shape of the lower die recess 53B is substantially rectangular. The width (the length in the longitudinal direction of the groove 35; therefore, the length in the axial direction of the material tube 37) W3 of the lower mold recess 53B is slightly more than twice the outer diameter R of the material tube 37 To a large extent, more precisely, it is about the same size as the sum of the total thickness of the first protruding member 55A and the two second protruding members 55B ₁ and 55B ₂ described later twice the outer diameter of the material tube 37 Or a slightly larger dimension, ie, if the thickness of the first ejection member 55A and the two second ejection members 55B ₁ , 55B ₂ is T, respectively, then [R × 4 + T × 3] or above It is set to a slightly larger degree. Further, the distance W4 (see FIG. 14) before and after the lower die recess 53B is set to be equal to or slightly larger than the outer diameter R of the material tube 37.

Furthermore, in the upper mold concave portion 53A of the upper mold member 33A, a first projecting member (hereinafter referred to as an upper mold pushing member) 55A is disposed so as to be able to advance and retract downward, while the lower mold member 33B is In the mold recess 53B, a pair of second projecting members (hereinafter referred to as lower die projecting members) 55B ₁ and 55B ₂ are disposed so as to be capable of advancing and retreating upward.

These upper mold protruding member 55A and a pair of lower die protruding member 55B _1, 55B _2, like the extension member 41 in the first embodiment, respectively, the direction orthogonal to the axis direction of the vertical direction (hence material pipe 37 In the shape of a long plate or a bar along the Then, the upper die protruding member 55A is advanced and retracted in the vertical direction by the advancing and retracting driving means 57A such as a fluid pressure cylinder at the central portion of the upper die recess 53A (the center of the upper die recess 53A in the length direction of the groove 35). Are configured to Further, the pair of lower mold projecting members 55B ₁ and 55B ₂ are advancing and retracting driving means 57B ₁ and 57B such as fluid pressure cylinders at both ends of the lower mold recess 53B (both ends of the lower mold recess 53B in the lengthwise direction of the groove 35). ₂ is configured to advance and retract along the vertical direction.

Next, a process of performing the method of the fourth embodiment using the apparatus shown in FIGS. 12 to 14 will be described with reference to FIGS. 15 (a) to (d). In this embodiment, as shown in FIG. 15 (a), at the stage before the start of processing only when the mold clamping is performed, the lower mold projecting members 55B ₁ and 55B ₂ have their tips at the lower surface of the material pipe 37. It is in a state of being retracted so as to be located at or below the contact position. On the other hand, as shown by the solid line in FIG. 15 (a), the upper die protruding member 55A is normally retracted to the position of the inner bottom surface of the upper die recess 53A, but in some cases it enters the next step. At the previous stage, it is also permitted to lower the tip end (lower end) of the upper die protrusion member 55A to a position in contact with the upper surface of the material pipe 37 as shown by the chain line in FIG.

  Then, after the material pipe 37 is filled with a liquid for applying hydraulic pressure such as water, while the hydraulic pressure is applied and axial pressing is performed, as shown in FIG. 15 (b), the upper die protruding member 55A is lowered. Let Thus, the middle portion of the material tube 37 is bent downward and pushed into the lower die recess 53B. That is, the first bent portion 37E protruding downward is formed.

Next, as shown in FIG. 15C, the pair of lower die protruding members 55B ₁ and 55B ₂ are simultaneously lifted at the same speed. As a result, the portions on both sides of the first bending portion 37E in the middle portion of the raw material tube 37 are bent and deformed upward, and are pushed into the upper die recess 53A. That is, a pair of second bending portions 37F and 37G protruding upward are formed on both sides of the first bending portion 37E.

After the upper surfaces of the second bent portions 37F and 37G come in contact with the inner bottom surface of the upper die recess 53A in this manner, if the fluid pressure is increased while pressing the shaft further, finally, it is shown in FIG. as such, along the outer surface of the first bending point 37E is on the inner bottom surface and side surfaces of the lower mold ejector member _55B 1, 55B ₂ of the lower die recess 53B, and a pair of second bending portions 37F, the upper die is the outer surface of the 37G It is shaped so as to conform to the inner bottom surface and the side surface of the recess 53A and the side surface of the upper die protrusion member 55A.

  The appearance of the hollow tube having a bent portion obtained in this manner is shown in FIG. As shown in FIG. 16, the hollow tube 5 is formed between two straight tube portions 1A, 1B having a common axis O at right angles to the axial direction of the straight tube portions 1A, 1B and alternately It has three U-shaped bent portions 3A, 3B, 3C projecting in the opposite direction. That is, it has a portion bent in an inverted W shape as a whole.

In the fourth embodiment described above, the counter member is not used, but the counter member may be used as in the third embodiment (see FIGS. 9 to 11), and an example in that case is the As 5 embodiment, it shows in FIG. 17, FIG.
Note that, in FIG. 17, except for the respective counter members and the advancing and retracting driving means for driving the respective counter members, the embodiment is the same as the embodiment shown in FIGS. 9 to 11.

In FIG. 17, a pair of counter members (hereinafter referred to as upper die counter members) 49A ₁ and 49A ₂ are disposed in the upper die recess 53A at portions corresponding to both sides of the upper die protrusion member 55A, Further, in the lower die recess 53B, a counter member (hereinafter referred to as a lower die counter member) 49B is disposed at a position between the pair of lower die protruding members 55B ₁ and 55B ₂ . Each of these counter members 49A ₁ , 49A ₂ , 49B is configured to be advanced and retracted by an advancing and retracting drive means such as a fluid pressure cylinder not shown.

A process for implementing the method of the fifth embodiment using the apparatus shown in FIG. 17 will be described with reference to FIGS. 18 (a) to 18 (d). Incidentally, in this embodiment, the machining before starting the just performed clamping, as shown in FIG. 18 (a), the lower mold ejector member 55B _1, 55B ₂ has its leading end (upper end) of material pipe 37 The lower die counter member 49B is advanced to a position where the upper surface thereof comes in contact with the lower surface of the material pipe 37. On the other hand the upper mold projecting member 55A, as its tip (lower end) is in contact with the upper surface of the material pipe 37, also the upper mold counter member 49A _1, 49A ₂ also is positioned so that its lower surface is in contact with the upper surface of the material pipe 37 Keep it.

  Then, after the material pipe 37 is filled with a fluid for applying hydraulic pressure such as water, while the hydraulic pressure is applied and axial pressing is performed, as shown in FIG. 18B, the upper die protruding member 55A is lowered. At the same time, the lower mold counter member 49B is lowered at a constant velocity. As a result, the middle portion of the material tube 37 is bent downward while its lower surface is in contact with the upper surface of the lower mold counter member 49B, and is pushed into the lower mold recess 53B. That is, the first bent portion 37E protruding downward is formed.

Then, as shown in FIG. 18 (c), and at the same time raising the pair of the lower mold ejector member _55B 1, 55B ₂ simultaneously at a constant speed, raising the pair of upper mold counter member _49A 1, 49A ₂ at the same speed . Thus, of the intermediate portion of the material pipe 37, both side portions of the first bending point 37E is, the upper mold counter member 49A _1, is deformed bending upward while in contact with the upper surface of the 49A _2, the upper die recess 53A in Pushed into. That is, a pair of second bending portions 37F and 37G protruding upward are formed on both sides of the first bending portion 37E.

Thus, while the upper mold counter members 49A ₁ and 49A ₂ reach the upper limit position (the position where the upper surface of the upper mold counter members 49A ₁ and 49A ₂ is in contact with the inner bottom surface of the upper mold recess 53A), Finally, as shown in FIG. 18D, the outer surface of the first bent portion 37E is formed on the side surface of the lower projecting member 55B ₁ , 55B ₂ and the upper surface of the lower counter 49B. along, and a pair of second bending portions 37F, the inner surface of the upper mold recess 53A is an outer surface of 37G, so that the upper die extension member 55A side and the upper mold counter member _49A 1, 49A ₂ of a shape along the lower surface Molded into
As described above, in the fifth embodiment, since the counter member is used as in the third embodiment described above, there is no extra space above or below the bending portion while the bending deformation is in progress. It is possible to effectively prevent the occurrence of a situation where the diameter of the material tube is locally expanded or deformed to an abnormal shape and the original correct bending shape can not be obtained.

Furthermore, according to the method of the present invention, a hollow tube having two U-shaped bent portions continuously and in reverse directions, for example, two straight tube portions 1A having a common axis O as shown in FIG. , 1B, a first U-shaped bent portion 3A protruding in one direction perpendicular to the axial direction of the straight pipe portions 1A, 1B, and a direction opposite to the protruding direction of the U-shaped curved portion 3A It is also possible to produce hollow tubes in which the second U-shaped bend 3B projecting in the direction is formed continuously, that is to say a hollow tube having a substantially S-shaped bend.
An example in that case is shown in FIGS. 20 and 21 as a sixth embodiment.

Basically, the apparatus shown in FIG. 20 is one of the pair of lower die protrusion members 55B ₁ and 55B ₂ (55 B ₂ ) in the fifth embodiment (see FIG. 17 and FIG. 18), and the upper die counter. It can be said that _{one of} the members 49A ₁ and 49A ₂ (49A ₂ ) is omitted.
The process is shown in FIG. 21 by processing the material tube 37 using an apparatus having such a configuration. The process of FIG. 21 basically conforms to the process of the fifth embodiment shown in FIG. 18, and therefore the detailed description of the process is omitted here.
Here, as shown in FIG. 21 (b), after the upper die protruding member 55A and the lower die counter member 49B are lowered to form the lower U-shaped bent portion, as shown in FIG. 21 (c). raising the lower mold projecting member 55B ₁ and the upper mold counter member 49A _1, but forms an upper U-shaped bend, in some cases, a lowering of the upper mold ejection member 55A and the lower mold counter member 49B, by performing the rise of the lower mold ejector member 55B ₁ and the upper mold counter member 49A ₁ at the same time at a constant speed, the upper and lower U-shaped bend portions may be formed at the same time.

  Furthermore, according to the method of the present invention, a hollow tube 5 having a two-step U-shaped bend, ie, between two straight tube parts 1A, 1B having a common axis O, as shown in FIG. A relatively large U-shaped bent portion 3H is formed projecting in a direction perpendicular to the axial direction of the straight pipe portions 1A and 1B, and further, an intermediate in the relatively large U-shaped curved portion 3H It is also possible to produce a hollow tube 5 in which a relatively small U-shaped bend 3I is formed in the part (top part). An example of manufacturing a hollow tube having such a two-step U-shaped bent portion is shown as a seventh embodiment in FIGS.

In FIG. 23, the upper die member 33A is formed with a recess (hereinafter referred to as a large recess) 57 having a relatively large width W2a in the length direction of the groove 35 as a recess continuous with the upper die groove 35A. Furthermore, as a recess recessed from the inner bottom surface of the large recess 57, a recess (hereinafter referred to as a small recess) 59 having a relatively small width W2b in the length direction of the groove 35 is formed. In the small recess 59, a counter member 49C which is advanced and retracted in the vertical direction by an advancing and retracting driving means 61 such as a fluid pressure cylinder is disposed.
On the other hand, a protruding block 63 is provided on the lower mold member 33B so as to be able to move up and down. The projecting block 63 is moved up and down by the advancing and retracting driving means 65 such as a fluid pressure cylinder, and the projecting block 63 is a projecting member 67 similar to the projecting member 41 in the first embodiment. The projecting member 67 is movable relative to the projecting block 63 by means of advancing and retracting driving means 69 such as a fluid pressure cylinder fixed to the projecting block 63.

The process of forming a two-step U-shaped bent portion on the material pipe 37 using the apparatus shown in FIG. 23 is shown in FIGS. 24 (a) to 24 (d).
In the stage in which the material pipe 37 is set in the mold 31 and the material pipe 37 is filled with a liquid such as water for applying hydraulic pressure and clamped (see FIG. 24A), the protrusion block 63 has its upper surface Is in contact with the lower surface of the material pipe 37, and the lower surface (tip end surface) of the counter member 49C is flush with the inner bottom surface of the large recess 57.

  Then, as shown in FIG. 24 (b), while the liquid pressure application and axial pressing are performed, if the protruding block 63 is raised as a whole, the middle portion of the material pipe 37 is pushed into the large recess 57, A relatively large U-shaped bend 3H is formed.

  Then, while continuing the application of fluid pressure and axial pressing, as shown in FIG. 24C, the projecting member 67 is raised relative to the projecting block 63, and the counter member 49C is lifted at a constant velocity. For example, the middle portion of the above-mentioned relatively large U-shaped bent portion 3A in the material tube 37 is pushed into the small recess 59, and a relatively small U-shaped curved portion 3I is formed. Thereafter, if axial pressing and hydraulic pressure application are further performed, as shown in FIG. 24D, the U-shaped bent portions 3H and 3I are applied to the inner surfaces of the large recess 57 and the small recess 59 and the lower surface of the counter member 49C. It is molded into a shape along with it.

  In each of the above embodiments, the raw material tube 37 before processing is shown as a straight one, but a bend may be given in advance by pre-processing. In that case, the shapes of the upper mold member 33A and the lower mold member 33B constituting the mold 31, in particular, the shapes of the upper mold groove 35A and the lower mold groove 35B constituting the groove portion 35 are adapted to the bending shape by pre-processing. It should be set. An example in that case (an example according to the first embodiment) is shown as an eighth embodiment in FIG.

  Further, as described above, with respect to a hollow tube having a U-shaped bent portion to be finally obtained, two straight tube portions 1A having a common axis O, referring to (a) or (b) of FIG. The hollow tubes 5 are described as having a U-shaped bent portion 3 projecting in a direction perpendicular to the axial direction of the straight pipe portions 1A, 1B between 1B. The two straight pipe portions 1A and 1B may not necessarily have the common axis O, and in the case where the axis of one straight pipe portion 1A and the axis of the other straight pipe portion 1B form an angle. Is also applicable. An example of a device for forming a bent portion in that case is shown in FIG. 26 as a ninth embodiment.

  Furthermore, in the method of the present invention, it is also possible to simultaneously form U-curved portions at two or more places separated in the length direction of the material tube 37. An example of the device configuration in that case is shown in FIG. 27 as a tenth embodiment. In the tenth embodiment, basically, two components similar to those of the first embodiment are provided side by side in the longitudinal direction of the groove portion 35 in the same mold 31. It is a thing. That is, two recessed portions 39 are formed at positions separated in the length direction of the groove portion 35 in the upper mold member 33A, and the protruding members 41 are respectively formed at positions corresponding to the respective recessed portions 39 in the lower mold member 33B. It is considered to be arranged.

  In addition, as a method for forming a U-shaped bent portion at two or more places separated in the length direction of the material pipe 37, for example, as shown in FIG. The first U-shaped bent portion 3J is formed in the portion by the method of the present invention (for example, the method according to the first embodiment), and then again at another place in the material tube 37. By forming the second U-shaped bent portion 3K by the method according to the embodiment and repeating such a process one after another, a hollow tube having a large number of U-shaped bent portions 3J, 3K, 3L can be manufactured. .

  In each of the above-described embodiments, the inner bottom and side surfaces of the recess 39 are substantially flat surfaces, and the outer surface of the projecting member 41 is also substantially flat except for the curved surface of the tip. In the method of the present invention, the shape of the inner bottom surface and the side surface of the recess 39 and the shape of the outer surface of the protruding member 41 are changed in the method of the present invention. Thereby, it is possible to form a U-shaped bent portion having various cross-sectional shapes.

For example, when it is desired to obtain a U-shaped bent portion having a circular cross-sectional shape, as shown in FIGS. 29 and 30, the cross-sectional shape of the tip 41A and the side surfaces 41B and 41C of the protruding member 41 is a half curved concave. What is necessary is just to make it circular, and just to make the cross-sectional shape of the inner bottom face 39C and side 39D, 39E of the recessed part 39 into concave semicircular shape. For example, when it is desired to obtain a U-shaped bent portion whose sectional shape is a polygon, as shown in FIGS. 31 and 32, the sectional shape of the tip 41A and the side surfaces 41B and 41C of the projecting member 41 is concave. The cross-sectional shape of the inner bottom surface 39C and the side surfaces 39D and 39E of the recess 39 may be a concave polygon. In addition, U-shaped bent portions having various cross-sectional shapes can be formed as needed.
When the counter member is disposed in the recess, instead of the cross-sectional shape of the inner bottom surface of the recess, the cross-sectional shape of the tip end surface of the counter member may be a concave curved semicircle or concave polygon as described above Of course it is good if it sets to.

  Examples of the present invention are shown below. The following examples are for confirming the action and effects of the present invention, and it is needless to say that the conditions described in the examples do not limit the technical scope of the present invention.

Example 1
Example 1 corresponds to the first embodiment, and as a mold, one shown in FIGS. 1 to 4 is used, and a material is produced according to the method shown in FIGS. 5 (a) to 5 (g). The tube was processed to produce a hollow tube with a U-shaped bend. Here, the groove 35 in the mold 31 has a circular cross section as a whole and has an inner diameter of 38.1 mm. The recess 39 of the upper mold member 33A has a width W2 (distance between the inner side surfaces 39A and 39B) W2 of 85.0 mm in the longitudinal direction of the groove 35, and an inner surface in the direction orthogonal to the longitudinal direction of the groove 35. The distance W1 is 40.0 mm, and the depth is 120.0 mm. On the other hand, as the protrusion member 41, one having a thickness T of 5.0 mm and a tip surface curved in a convex shape with a curvature radius of 2.5 mm was used. As the raw material pipe 37, a hollow pipe made of carbon steel pipe for machine structure: STKM 13B and having an outer diameter of 38.1 mm and a thickness of 2.3 mm was used.

  Specifically, the tube end sealing members 45A and 45B are attached to both ends of the material tube 37, disposed in the groove 35, filled with water as pressurizing liquid in the material tube, and disposed in the groove 35, the mold After tightening, a pressure (axial pushing force) of 50 kN was applied to the pipe end sealing member in the axial direction, and a pressure of 20 MPa was applied to the pressurizing liquid in the material pipe 37. Then, while continuing the axial pushing and the hydraulic pressure application, the raw material pipe 37 is axially pushed from both sides at a speed of 5.0 mm / sec, and the ejection member 41 is raised at a speed of 5.0 mm / sec. . Then, at the stage when a part of the raw material pipe was in contact with the inner bottom surface of the recess 39, the rising of the protruding member 41 was stopped and the liquid pressure was raised to 80 MPa.

  As a result, it was possible to obtain a hollow tube having a U-shaped bend as shown in FIG. Here, when the hollow tube product after shaping | molding was investigated, it was confirmed that it is correctly processed into the shape along a recessed part inner surface. Furthermore, it was also confirmed that the external appearance of the outer peripheral surface of the U-shaped bent portion had a good appearance quality, particularly without the occurrence of cracks, asperities and wrinkles.

Example 2
The second embodiment corresponds to the second embodiment, and the same manufacturing apparatus as that of the first embodiment is used, and the material pipe is a carbon steel pipe for machine structure similar to the first embodiment. : A hollow tube having a U-shaped bent portion by processing a material pipe according to the method shown in FIGS. 7 (a) to 7 (d) using an STKM 13B outer diameter of 38.1 mm and a thickness of 2.3 mm. The tube was manufactured. Here, the groove 35 of the mold 31 has a circular cross section as a whole and has an inner diameter of 38.1 mm. The recess 39 of the upper mold member 33A has a width W2 (distance between the inner side surfaces 39A and 39B) W2 of 85.0 mm in the longitudinal direction of the groove 35, and an inner surface in the direction orthogonal to the longitudinal direction of the groove 35. The distance W1 is 40.0 mm, and the depth is 120.0 mm. On the other hand, as the protrusion member 41, one having a thickness T of 5.0 mm and a tip surface curved in a convex shape with a curvature radius of 2.5 mm was used.

  Similar to Embodiment 1, tube end sealing members 45A and 45B are attached to both ends of the material tube 37, disposed in the groove 35, filled with water as pressurizing liquid in the material tube, and disposed in the groove 35, After clamping, after clamping, a pressure of 50 kN (axial pushing force) was applied in the axial direction to the tube end sealing member, and a pressure of 20 MPa was applied to the pressurizing liquid in the material tube 37 . Then, while continuing the axial pushing and the application of hydraulic pressure, the raw material pipe 37 is axially pushed from both sides at a speed of 5.0 mm / sec, and the protruding member 41 is raised at a speed of 5.0 mm / sec. The projecting member 41 was lowered at a time before the material tube was brought into contact with the inner bottom surface of 39. Subsequently, axial pressing and application of hydraulic pressure were continued, and when a portion of the material pipe was in contact with the inner bottom surface of the recess 39, the hydraulic pressure was raised to 80 MPa.

  As a result, it was possible to obtain a hollow tube having a U-shaped bend as shown in FIG. 8, that is, a hollow tube having a substantially zero inner radius of curvature of the U-shaped bend. Here, when the hollow tube product after shaping | molding was investigated, it was confirmed that it is processed with the shape along the recessed part inner surface with high precision. Furthermore, it was also confirmed that the external appearance of the outer peripheral surface of the U-shaped bent portion had a good appearance quality, particularly without the occurrence of cracks, asperities and wrinkles.

[Example 3]
This example 3 corresponds to the third embodiment, and as a mold, one having a counter member 49 as shown in FIGS. 9 and 10 is used, as shown in FIGS. The raw material pipe was processed according to the method shown in 2.) to produce a hollow pipe having a U-shaped bent portion.

Here, the groove 35 in the mold 31 has a circular cross section as a whole and has an inner diameter of 38.1 mm. The recess 39 of the upper mold member 33A has a width W2 (distance between the inner side surfaces 39A and 39B) of 85.0 mm in a direction orthogonal to the lengthwise direction of the groove 35 in the lengthwise direction of the groove 35. The distance W1 between the inner surfaces is 40.0 mm and the depth is 140.0 mm, and the thickness of the counter member 49 is 20.0 mm. Therefore, the depth from the open end of the recess 39 to the tip end face of the counter member 49 in the state where the counter member 49 is fully retracted is 120.0 mm.
On the other hand, as the protrusion member 41, one having a thickness T of 5.0 mm and a tip surface curved in a convex shape with a curvature radius of 2.5 mm was used. As the raw material pipe 37, a hollow pipe made of carbon steel pipe for machine structure: STKM 13B and having an outer diameter of 38.1 mm and a thickness of 2.3 mm was used.

  Similar to Embodiment 1, tube end sealing members 45A and 45B are attached to both ends of the material tube 37, disposed in the groove 35, filled with water as pressurizing liquid in the material tube, and disposed in the groove 35, After clamping, after clamping, a pressure of 50 kN (axial pushing force) was applied in the axial direction to the tube end sealing member, and a pressure of 20 MPa was applied to the pressurizing liquid in the material tube 37 . Then, while continuing the axial pushing and the application of hydraulic pressure, the raw material pipe 37 is axially pushed from both sides at a speed of 5.0 mm / sec, and the projecting member 41 is raised at a speed of 5.0 mm / sec. Similarly, while raising the counter member 49 at a speed of 5.0 mm / sec and stopping the rising of the ejection member 41 when the upper surface of the counter member 49 is in contact with the inner bottom surface of the recess 39, the fluid pressure is increased to 80 MPa. I did.

  As a result, as in the case of Example 1, a hollow tube having a U-shaped bent portion as shown in FIG. 6 was obtained. Here, when the hollow tube product after shaping | molding was investigated, it was confirmed that it is correctly processed into the shape along a recessed part inner surface. Furthermore, it was also confirmed that the external appearance of the outer peripheral surface of the U-shaped bent portion had a good appearance quality, particularly without the occurrence of cracks, asperities and wrinkles.

Example 4
This example 4 corresponds to the fourth embodiment, and as a mold, one shown in FIGS. 12 to 14 is used, and a material is produced according to the method shown in FIGS. 15 (a) to 15 (d). The tube was processed to produce a hollow tube having a plurality of U-shaped bent portions in a substantially W shape as shown in FIG. Here, the groove 35 in the mold 31 has a circular cross section as a whole and has an inner diameter of 38.1 mm. The upper mold recess 53A of the upper mold member 33A has a width W2 of 175.0 mm in the direction along the longitudinal direction of the groove 35 (the distance between the inner side surfaces 39A and 39B) and a direction orthogonal to the longitudinal direction of the groove 35 The distance W1 between the inner surfaces of the above was 40.0 mm, and the depth was 120.0 mm. On the other hand, the lower mold recess 53B of the lower mold member 33B has a width W3 of 85.0 mm in the direction along the lengthwise direction of the groove 35 (the distance between the inner side surfaces 39A and 39B) and is orthogonal to the lengthwise direction of the groove 35 The distance W4 between the inner surfaces in the direction is 40.0 mm, and the depth is 120.0 mm. Further, as each protruding member (upper die protruding member 55A, lower die protruding members 55B ₁ , 55B ₂ ), the thickness T is 5.0 mm and the tip end surface is curved in a convex shape with a curvature radius of 2.5 mm. Was used. As the raw material pipe 37, a hollow pipe made of carbon steel pipe for machine structure: STKM 13B and having an outer diameter of 38.1 mm and a thickness of 2.3 mm was used.

Specifically, the tube end sealing members 45A and 45B are attached to both ends of the material tube 37, disposed in the groove 35, filled with water as pressurizing liquid in the material tube, and disposed in the groove 35, the mold After tightening, a pressure (axial pushing force) of 50 kN was applied to the pipe end sealing member in the axial direction, and a pressure of 20 MPa was applied to the pressurizing liquid in the material pipe 37. Then, while continuing the axial pushing and the hydraulic pressure application, the raw material pipe 37 is axially pushed from both sides at a speed of 5.0 mm / sec, and the upper die protruding member 55A is lowered at a speed of 5.0 m / sec. I did. When the raw material pipe comes in contact with the inner bottom surface of the lower mold recess 53B, the descent of the upper die protrusion member 55A is stopped, and the lower die protrusion members 55B ₁ and 55B ₂ are lifted (rise speed 5.0 mm / sec ) Was started. Next, at the stage when a part of the raw material pipe was in contact with the inner bottom surface of the upper die recess 53A, the raising of the lower die protruding members 55B ₁ and 55B ₂ was stopped and the fluid pressure was raised to 80 MPa.

  As a result, it was possible to obtain a hollow tube having a substantially W-shaped bent portion in which a plurality of U-shaped bent portions are continuous as shown in FIG. Here, when the hollow tube product after shaping | molding was investigated, it was confirmed that it is correctly processed into the shape along a recessed part inner surface. Furthermore, it was also confirmed that the external appearance of the outer peripheral surface of the U-shaped bent portion had a good appearance quality, particularly without the occurrence of cracks, asperities and wrinkles.

  Although the preferred embodiments and examples of the present invention have been described above, the present invention is of course not limited to these embodiments and examples, and additions and omissions of configurations are possible without departing from the scope of the present invention. , Substitution, and other changes are possible.

  The method and apparatus for manufacturing a U-shaped bent pipe according to the present invention is a heat exchanger, or an automobile part, an interior part of an building, an exterior part of an building, an outdoor device such as a gate, other parts of a chemical plant, or parts of various liquid processing devices Suitable for the production of hollow tubes used in

1A, 1B Straight pipe portion 3, 3A to 3L U-shaped bent portion 5 Hollow tube 31 Mold 33A Upper mold member 33B Lower mold member 35 Groove portion 37 Material tube 37A, 37B Both end portions 39, 53A, 53B Recesses 41, 55A, 55B ₁ , 55B ₂ ejection members 42, 42A ₁ , 42A ₂ , 42B advancing and retracting driving means 45A, 45B tube end sealing members 49, 49A ₁ , 49A ₂ , 49B counter members

Claims (15)

Between two or more straight pipe section, around the producing hollow tube having a U-shaped bend portion projecting with respect to the axial direction of the straight pipe section in a direction forming a predetermined angle,
A groove is formed between the mold member forming the upper mold and the mold member forming the lower mold, into which a hollow tube-shaped material tube is inserted, and at least one of the upper and lower mold members is formed of At least one recess is formed continuous with the space in the groove and recessed toward the inside of the other mold member, and at least on the side of the other mold member, the space in the groove passes through the space in the groove Using a mold provided with at least one push-out member that can move back and forth
A raw material pipe is disposed in the groove, and both ends of the raw material pipe are sealed by a pipe end sealing member which doubles as an axial pushing member, and liquid pressure is applied to the inner space of the raw material pipe. The pressing member is advanced from the side of the other mold member toward the inside of the recess while pressing in the direction along the axis from the above, and the longitudinal middle portion of the material tube is pushed into the recess, A method of manufacturing a hollow tube having a U- shaped bent portion , wherein the U- shaped bent portion of the material tube is formed in the concave portion by the
After stopping the advancing of the push-up member, the U-curved portion in the concave portion is raised by increasing the hydraulic pressure applied to the inner space of the raw material pipe while continuing the pressurization in the axial direction of the raw material pipe. A method of manufacturing a hollow tube having a U-shaped bent portion, characterized by forming into a shape along the inner surface of a recess. Between two or more straight pipe section, around the producing hollow tube having a U-shaped bend portion projecting with respect to the axial direction of the straight pipe section in a direction forming a predetermined angle,
A groove is formed between the mold member forming the upper mold and the mold member forming the lower mold, into which a hollow tube-shaped material tube is inserted, and at least one of the upper and lower mold members is formed of At least one recess is formed continuous with the space in the groove and recessed toward the inside of the other mold member, and at least on the side of the other mold member, the space in the groove passes through the space in the groove Using a mold provided with at least one push-out member that can move back and forth
A raw material pipe is disposed in the groove, and both ends of the raw material pipe are sealed by a pipe end sealing member which doubles as an axial pushing member, and liquid pressure is applied to the inner space of the raw material pipe. The pressing member is advanced from the side of the other mold member toward the inside of the recess while pressing in the direction along the axis from the above, and the longitudinal middle portion of the material tube is pushed into the recess, A method of manufacturing a hollow tube having a U- shaped bent portion , wherein the U- shaped bent portion of the material tube is formed in the concave portion by the
In the middle of the process of advancing the extruding member and pushing the middle portion in the longitudinal direction of the material tube into the recess, the advancing member is stopped from advancing, and the extruding member is subsequently retracted, and after the advancing member stops advancing, A U-shaped curved portion is characterized in that the middle portion of the material tube is pushed into the recess by only the hydraulic pressure applied to the inner space of the material tube and the pressure applied along the axial direction from both ends to the material tube. The manufacturing method of the hollow tube which it has. After stopping the advancing of the push-up member, the U-curved portion in the concave portion is raised by increasing the hydraulic pressure applied to the inner space of the raw material pipe while continuing the pressurization in the axial direction of the raw material pipe. The method for manufacturing a hollow tube having a U-shaped bent portion according to claim 2, characterized in that the shape is formed along the inner surface of the recess . The mold further includes a counter member capable of advancing and retracting to the other mold member in the recess, in the one mold member.
The projecting member is advanced to push the middle portion of the material tube into the recess, and at the same time, the counter member is retracted while bringing the outer surface of the middle portion of the material tube into contact with the tip end surface of the counter member. The manufacturing method of the hollow tube which has a U-curved part as described in any one of the Claims 1-3 .   After stopping the advancement of the push-up member and the retraction of the counter member, the U-curved portion is formed by increasing the hydraulic pressure applied to the inner space of the material pipe while continuing the pressurization in the axial direction of the material pipe. The method for manufacturing a hollow tube having a U-shaped bent portion according to claim 4, characterized in that: is formed in a shape along the tip surface of the counter member and the inner surface of the recess.   As the mold, one of the mold members of the upper and lower mold members is formed with one recess which is continuous with the space in the groove and is recessed toward the inside of the other mold member, and at least the other The mold according to any one of claims 1 to 5, wherein one of the projecting members is provided on the side of the mold member through the space in the groove and can move back and forth into the recess. A method of manufacturing a hollow tube having a U-shaped bent portion according to claim 1.   As the mold, in one mold member of the upper and lower mold members, two or more recesses continuous with the space in the groove and recessed toward the inside of the other mold member in the length direction of the groove The other mold member is provided with two or more projecting members formed at intervals and capable of advancing and retracting into the respective recesses through spaces in the groove corresponding to the two or more recesses. The method for producing a hollow tube having a U-shaped bent portion according to any one of claims 1 to 5, wherein a mold is used. As the mold, one or more first projecting members are disposed on the other mold member at predetermined intervals in the lengthwise direction of the groove, and one or more second members are disposed on the one mold member. A protruding member disposed at a position shifted by a predetermined distance in the longitudinal direction of the groove with respect to the position of the first protruding member, and the one mold member corresponds to the first protruding member A first recess is formed, and a second recess corresponding to the second projecting member is formed on the other mold member,
A raw material pipe is disposed in the groove, and both ends of the raw material pipe are sealed by a pipe end sealing member which doubles as an axial pushing member, and liquid pressure is applied to the inner space of the raw material pipe. And pressing the first projecting member from the side of the other mold member while pressing in the direction along the axis of the tube, and pushing the middle portion in the longitudinal direction of the material tube into the first recess, Then, from the side of the one mold member, the second projecting member is advanced to push the middle portion in the longitudinal direction of the material pipe into the second recess, thereby the middle portion in the longitudinal direction of the material pipe The hollow tube having a U-shaped curved portion according to any one of claims 1 to 5, wherein two or more U-shaped curved portions which are continuously bent in opposite directions to each other are formed. Manufacturing method. As the mold, one having at least one mold member provided with a counter member capable of advancing and retracting to the other mold member in the recess thereof is further used.
The at least one projecting member is advanced to push the middle portion of the material tube into the recess, and at the same time the counter member is retracted while bringing the outer surface of the middle portion of the pressed material tube into contact with the tip end surface of the counter member The method for producing a hollow tube having a U-shaped bent portion according to claim 8, characterized in that: As the mold, two first projecting members are disposed on the other mold member at predetermined intervals in the longitudinal direction of the groove, and one second projecting member is disposed on the one mold member. A member is disposed at an intermediate position between the two first projecting members, and the one mold member is formed with a first recess corresponding to the first projecting member, and the other mold member In the second embodiment, a second recess corresponding to the second projecting member is used.
The U-shaped portion according to any one of claims 8 and 9, characterized by forming three U-shaped bent portions continuously bent in opposite directions in an intermediate portion in the longitudinal direction of the material tube. The manufacturing method of the hollow tube which has a bending part.   The method according to any one of claims 1 to 10, after forming one or more U-shaped bent portions at a predetermined location in the middle portion of the material tube, further forming another portion of the middle portion of the material tube Forming a hollow tube having a large number of U-shaped bends by performing one or more times the steps of forming one or more U-shaped bends in the same way by the same method. The manufacturing method of the hollow tube which has a bending part.   The method according to any one of claims 1 to 10, after forming one or more U-shaped bent portions at a predetermined position in the middle portion of the material pipe, further forming the middle of the U-shaped bent portions U-bending characterized in that a hollow tube having a large number of bends is produced by performing one or more times the step of forming another one or more U-shaped bends in the portion by the same method. Method of manufacturing a hollow tube having a part An apparatus for manufacturing a hollow tube having a U-shaped bent portion projecting in a direction forming a predetermined angle with the axial direction of a straight pipe portion between two or more straight pipe portions,
A mold comprising a mold member constituting an upper mold and a mold member constituting a lower mold ;
A tube end sealing member which is removable from both ends of the hollow tube and has a flow path;
Mechanical pressing means for pressing and driving the tube end sealing member;
Equipped with
And a groove is formed between the two mold members into which a hollow tubular material tube is inserted, and at least one mold member of the two mold members is continuous with the space in the groove and the other is At least one recess which is recessed toward the inside of the mold member, and at least on the other side of the mold member, at least one projecting member capable of advancing and retracting into the recess through a space in the groove Is provided ,
The at least one projecting member is controlled to be advanced and retracted by the advancing and retracting driving means, and after the advancing and retracting driving means stops the advancement of the pushing-up member, the axial pressurization of the material tube by the mechanical pressurizing means is continued An apparatus for manufacturing a hollow tube having a U-shaped bent portion, characterized in that the fluid pressure applied to the inner space of the material tube through the flow path of the tube end sealing member is increased while being allowed to . An apparatus for manufacturing a hollow tube having a U-shaped bent portion projecting in a direction forming a predetermined angle with the axial direction of a straight pipe portion between two or more straight pipe portions,
A mold comprising a mold member constituting an upper mold and a mold member constituting a lower mold ;
A tube end sealing member which is removable from both ends of the hollow tube and has a flow path;
Mechanical pressing means for pressing and driving the tube end sealing member;
Equipped with
And a groove is formed between the two mold members into which a hollow tubular material tube is inserted, and at least one mold member of the two mold members is continuous with the space in the groove and the other is At least one recess which is recessed toward the inside of the mold member, and at least on the other side of the mold member, at least one projecting member capable of advancing and retracting into the recess through a space in the groove Is provided ,
The at least one projecting member is controlled by advancing and retracting drive means, and the advancing and retracting drive means drives the advancing and retracting in the middle of the process of advancing the projecting member and pushing the middle portion in the longitudinal direction of the material tube into the recess. The means stops the advancing of the protruding member, and subsequently retracts the protruding member, and after stopping the advancing of the protruding member, the liquid applied to the inner space of the material pipe through the flow path of the pipe end sealing member U is characterized in that the middle portion of the material tube is pushed into the recess only by the pressure and the pressure force applied to the material tube from the both ends in the axial direction by the mechanical pressure means. The manufacturing apparatus of the hollow tube which has a bent part. The U-shaped character according to claim 13 or 14 , wherein the one mold member in the mold is provided with a counter member capable of advancing and retreating toward the other mold member in the recess. The manufacturing apparatus of the hollow tube which has a bending part.

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