JP2022110718A - Method for manufacturing pipe material and its manufacturing apparatus - Google Patents

Abstract

To provide a method for producing a tube material capable of efficiently obtaining a formed tube with a desired cross-section.SOLUTION: A method for producing a tube material includes: a bending step of bending an element tube (T0) which is a tubular material having a closed cross section; and a forming step of obtaining a formed tube (T1) having a closed cross section different from that of the element tube by plastically deforming the bent element tube. The bending step and the forming step may be performed by filling the element tube with incompressible fluid. The element tube is a round tube having a substantially round hollow closed cross section. The formed tube is, for example, a square tube having a substantially square hollow closed cross section. Forming is performed, for example, by; forming rolls contacting the element tube, as well as, surrounding the element tube; and press-moving means for press-moving each forming roll inward of the element tube. The bending and forming of the element tube are integrally performed by the forming rolls arranged shifted from the axis of the element tube.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a pipe material, and the like.

Not only straight pipes with a constant cross section, but also deformed pipes whose cross section, curvature, etc. change along the longitudinal direction are used as structural members (for example, pillars of automobiles, etc.). By using a deformed tube, both weight reduction and high mechanical properties (strength, rigidity, etc.) can be achieved at a high level.

The deformed pipe can also be manufactured entirely by welding plate materials or the like. However, if a deformed pipe is obtained by bending or forming a raw pipe with a basic cross-sectional shape (including pipes with a constant cross section as well as pipes with tailored blanks), the productivity can be improved. . A description related to this can be found in the following patent documents.

JP 2007-301587 JP 2014-87846

In Patent Document 1, only bending is performed on a prefabricated material (deformed pipe) whose circumferential length (cross section) changes in the axial direction (longitudinal direction). In Patent Document 2, a tubular material (base tube) having a constant cross section is formed into a desired cross section, and then the material (deformed tube) is subjected to bending.

A pipe member bent by such a conventional method tends to have a cross section different from a desired cross section (that is, deformed).

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a manufacturing method and the like by which a pipe material having a desired shape can be efficiently obtained.

As a result of intensive research aimed at solving this problem, the inventors of the present invention have found that the cross-section (shape) collapse can be suppressed by bending the raw material (base tube) and then forming it into a desired cross-section. Developing this result led to the completion of the present invention described below.

"Production method"
(1) The present invention includes a bending step of bending a blank pipe, which is a tubular material having a closed cross section, and a forming step of plastically deforming the bent blank pipe to obtain a formed pipe having a closed cross section different from that of the blank pipe. and a method for manufacturing a pipe material.

(2) According to the manufacturing method of the present invention, by plastically deforming the blank pipe while utilizing the stress state generated by the bending (forming) of the blank pipe, the formed pipe having a cross section different from that of the blank pipe is deformed. can be efficiently obtained while suppressing

"manufacturing device"
The present invention can also be grasped as a manufacturing apparatus. For example, the present invention includes feeding means for moving a blank tube, which is a tubular material having a closed cross section, in the longitudinal direction, supporting means for supporting the blank tube while moving the blank tube in the longitudinal direction, and the supporting means. and a forming means for plastically deforming the bent raw pipe into a formed pipe having a closed cross-section different from that of the raw pipe.

《Pipe materials, control devices, etc.》
The present invention can also be grasped as a pipe material (formed pipe) obtained by the manufacturing method described above. It can also be understood as a method or apparatus for controlling the manufacturing apparatus described above. The controlled object includes, for example, the feeding speed of the feeding means, the bending direction and curvature of the bending means, the form (shape and size) of the forming space of the forming means, and the like. By controlling these in accordance with the movement of the blank tube, it is possible to obtain a molded tube having different bending directions, curvatures, cross-sectional shapes, wall thicknesses, characteristics, etc., in the longitudinal direction. In addition, it is possible to obtain molded tubes having different wall thicknesses, characteristics, etc. in the circumferential direction.

The raw pipe and the formed pipe may have different outer peripheral lengths at corresponding cross-sectional positions. By bending or forming such that the outer peripheral lengths thereof are substantially equal, the shape (cross section) collapse can be further suppressed.

"others"
(1) The bending and forming of the blank tube as referred to in the present invention may be performed stepwise (sequentially), continuously, or substantially simultaneously (substantially integrally).

(2) The longitudinal direction referred to in this specification is the direction in which the pipe member (especially the raw pipe) extends. Tubing is normally transported in its longitudinal direction (axial direction). The tubing may be extruded from the upstream side, drawn from the downstream side, or fed in-between. The wall thickness of a tube is the width in a direction (radial direction) perpendicular to the axis passing through the center of the cross section.

(3) "Means", "process" or "step" in this specification can be read interchangeably. For example, by replacing "-step", which is a component of the method, with "means", it can be a component of the apparatus. Conversely, by replacing "means", which is a component related to the apparatus, with "process", it is possible to make it a component related to the method. Each means, each process or each step may be realized by executing a program on a computer. In this case, the present invention may be grasped as a control program for a manufacturing apparatus.

(4) Unless otherwise specified, "x to y" as used herein includes the lower limit value x and the upper limit value y. A new range such as “a to b” can be established as a new lower or upper limit of any numerical value included in the various numerical values or numerical ranges described herein. Unless otherwise specified, "x to ymm" as used herein means xmm to ymm. The same applies to other unit systems.

It is a schematic diagram showing a manufacturing apparatus (an example) of a pipe material. It is an enlarged view of the main part. 1 is a front view showing a drive control device (one example) for forming rollers; FIG. It is the side view. It is an analysis example related to a cross-sectional view of a forming tube.

In addition to the components of the present invention described above, one or more components arbitrarily selected from this specification may be added. The content described in this specification applies not only to manufacturing methods and manufacturing apparatuses, but also to pipe materials (especially molded pipes) as appropriate, and can be both method-related components and product-related components. Which embodiment is the best depends on the target, required performance, and the like.

《Piping》
(1) Material The pipe material (raw pipe or formed pipe) may be any of iron-based, aluminum-based, magnesium-based, titanium-based, and the like. A representative example of the pipe material is a steel pipe (for example, a high-strength steel pipe). As used herein, the term "-series" means that the material is a pure metal or an alloy.

The thickness (wall thickness) of the tubular material may be constant in the circumferential and longitudinal directions, or may vary in at least one of the circumferential and longitudinal directions. The thickness is appropriately selected, and is, for example, about 0.5 to 7 mm, further 0.8 to 4 mm.

(2) Base pipe The base pipe may have a constant cross section, wall thickness and material, or the cross section may vary in the longitudinal direction (axial direction). It may vary with respect to one. In this specification, a tubular member having a non-uniform cross section, wall thickness and material (especially a tubular member that varies in the longitudinal direction) is referred to as a deformed pipe.

The blank pipe may be a seamless pipe or a welded pipe. A seamless pipe is obtained, for example, by hot or cold pipe making (extrusion pipe, drawn pipe, etc.). A deformed pipe (base pipe) is manufactured, for example, by welding different pipe materials or steel plates according to the specifications of the formed pipe. As a blank tube, for example, there is a round tube having a substantially annular closed cross section. It should be noted that the term “substantially circular” as used in this specification includes ellipses regardless of the degree of circularity.

(3) Molded pipe A molded pipe is obtained by plastically working a blank pipe to which a bending stress is applied. The formed tube has a cross section different from that of the blank tube at least partially in the longitudinal direction. The forming tube need not necessarily be of annular closed cross-section. A molded pipe (structural member) that is not a pipe through which a fluid flows is sufficient as long as it has a form that satisfies the desired properties. Further, the formed pipe is not limited to a curved bent pipe, and may be a straight pipe formed by bending back a bent pipe.

As a formed tube, there is, for example, a square tube having a closed cross-section of a substantially angular annular shape. The closed cross section is, for example, a substantially triangular ring (triangular tube), a substantially square ring (square tube), a substantially pentagonal ring (pentagonal tube), a substantially hexagonal ring (hexagonal tube), or the like. As a representative example of the square tube, there is a rectangular tube (square tube) having a substantially rectangular annular (substantially square annular) closed cross section. In this specification, the term "substantially cornered" includes chamfering, rounding, and the like at the corners and corners, regardless of the precision of the corners and surfaces.

"Production method"
A formed pipe is obtained through a bending process and a forming process for a blank pipe. The bending process may be two-dimensional bending or three-dimensional bending. The molding process is carried out by passing the raw pipe through a molding space (cavity) or pushing the outer peripheral surface of the raw pipe. Further rotation, bending, etc. may be added during molding. At this time, if there is little change in the outer circumference lengths of the blank pipe and the formed pipe before and after forming, it is preferable because the deformation can be suppressed.

If the bending process or the forming process is hydrobending or hydroforming performed by filling an incompressible fluid into a blank pipe and further pressurizing it, the deformation of the formed pipe can be further suppressed.

"manufacturing device"
The manufacturing apparatus includes, for example, feeding means, supporting means, bending means, forming means, and the like.

The feeding means moves the blank tube in the longitudinal direction. When extruding (delivering) the blank pipe from the upstream side (the side opposite to the forming tube) to the downstream side, it is preferable to provide means for suppressing buckling of the blank pipe according to the length of the blank pipe. For example, it is preferable to provide at least a pair of opposing auxiliary rolls in contact with the blank tube in the intermediate region of the blank tube before bending. It is preferable that the auxiliary roll is interlocked with the movement of the blank pipe, or performs avoidance movement when the top end of the blank pipe approaches.

The support means supports the blank pipe while allowing the blank pipe to move in the longitudinal direction, and serves as a bending starting point (fulcrum) of the blank pipe. The support means comprises, for example, at least a pair of opposing support rolls that are in contact with the blank pipe according to the bending direction of the blank pipe. Moreover, when there are a plurality of bending directions of the blank tube (when it is three-dimensionally bent), it is preferable that there are at least two pairs of support rolls serving as bending starting points. For example, a pair of upper and lower support rolls and a pair of left and right support rolls may be arranged at the bending starting point. If such support rolls are arranged in at least two rows along the longitudinal direction of the blank pipe, the blank pipe can be supported more stably.

The bending means bends the raw pipe by changing the moving direction of the raw pipe before and after the bending starting point (supporting means) on the downstream side of the supporting means. The bending direction or curvature can be constant or variable along the length.

The shaping means plastically deforms the bent blank pipe to form a shaped pipe having a closed cross-section different from that of the blank pipe. The forming means are realized, for example, by at least two pairs of forming rolls which are in contact with and surround the blank pipe bent according to the closed cross-section of the forming pipe. A formed pipe having a desired cross section is obtained by passing the blank pipe through a gap (forming space) formed by the forming rolls.

If the forming means (for example, forming rolls) is arranged at a position deviating from the axis (moving direction) of the blank pipe on the upstream side of the bending starting point (supporting means), the forming means bends the blank pipe while forming. . In other words, the forming means also serves as the bending means, and both can be integrated.

As an example, consider the case of manufacturing a rectangular tube (forming tube) having a substantially rectangular annular closed cross section. and a pushing means for pushing inwardly of the tube. The pushing means comprises, for example, an actuator (cylinder, screw, etc.) driven hydraulically or electrically. By adjusting the gap (forming space) between the opposing forming rolls by means of a pushing means, a forming tube having a constant or variable cross section in the longitudinal direction can be obtained.

Another forming roll may be slid in conjunction with movement of a forming roll. For example, when the first forming roll is moved by the pushing means, the adjacent second forming roll may be slid synchronously. This makes it possible to stably maintain the gap (cavity) for forming the blank tube. The sliding of the second forming roll by the first forming roll can be performed, for example, by moving a block (interlocking member) or the like in contact with the second forming roll by the pushing means of the first forming roll. If the interlocking member is used, the drive source for sliding the second forming roll can be omitted.

The present invention will be described in more detail while showing a specific example of forming a round pipe (raw pipe) into a square pipe (rectangular pipe/formed pipe) having a rectangular cross section.

"Overview"
(1) Configuration An outline of a tube material manufacturing apparatus D (simply referred to as "apparatus D"), which is an embodiment of the present invention, is shown in FIGS. In this embodiment, unless otherwise specified, the directions indicated by arrows in the drawings are the up-down direction, the left-right direction, and the front-rear direction (moving direction of the blank tube).

The device D forms a straight round tube T0 whose cross section is constant in the longitudinal direction into a square tube T1 whose cross section is constant or varies in the longitudinal direction. The device D includes a forming roll 11, a first support roll 21 (support means), a second support roll 22, an auxiliary roll 23, and a check attached to the downstream end opening of the round tube T0 (square tube T1). 3, a check 4 attached to the upstream end opening of the round tube T0, feeding means (not shown) for pushing the round tube T0 downstream through the check 4, and a drive control device M for displacing the forming rolls 11. (described later).

The forming roll 11 includes a pair of forming rolls 111 and 112 facing each other in the vertical direction and a pair of forming rolls 113 and 114 facing each other in the horizontal direction. The outer peripheral surface of each forming roll consists of a cylindrical surface having a linear cross section. A square (rectangular) molding space s (cavity) corresponding to the outer shape of the square tube T1 is formed by each molding roll.

The first support roll 21 also includes a pair of support rolls 211 and 212 facing each other in the vertical direction and a pair of support rolls 213 and 214 facing each other in the left-right direction. The outer peripheral surface of each support roll consists of an annular curved surface whose cross section has a semicircular arc shape along the outer peripheral surface of the round tube T0. The first support roll 21 constitutes a bending starting point (fulcrum) of the round tube T0.

The second support roll 22 also includes a pair of support rolls 221 and 222 facing each other in the vertical direction and a pair of support rolls 223 and 224 (not shown) facing each other in the left and right direction. The second support roll 22 also has the same shape as the first support roll 21, and each outer peripheral surface is an annular curved surface whose cross section is a semicircular arc along the outer peripheral surface of the round tube T0. The second support rolls 22 cooperate with the first support rolls 21 to stably support the bendable round tube T0.

The auxiliary roll 23 also includes a pair of vertically opposed auxiliary rolls 231 and 232 and a pair of horizontally opposed auxiliary rolls 233 and 234 (not shown). The auxiliary roll 23 also has the same shape as the first support roll 21 and the second support roll 22, and each outer peripheral surface is an annular curved surface whose cross section is a semicircular arc along the outer peripheral surface of the round tube T0. The auxiliary roll 23 supports the round tube T0 between its upstream end and the second support roll 22 to prevent buckling of the round tube T0 when it is pushed.

The first support roll 21, the second support roll 22, and the auxiliary roll 23 can be adjusted in facing distance (gap) according to the outer diameter (outer width) of the round tube T0. As a result, each roll stably contacts and rolls on the outer surface of the round tube T0. Further, the auxiliary roll 23 can move in the front-rear direction, and moves in the rearward direction (downstream side) in conjunction with the progress of the round tube T0.

The check 3 liquid-tightly closes the downstream end opening of the round tube T0 (square tube T1), and also serves as a supply port for filling the inside of the tube with a liquid (for example, water or oil/incompressible fluid). For example, the liquid is filled in the pipe under pressure (about 0.1 to 10 MPa). Filling with such a liquid can further prevent wrinkles, deformation, and the like from occurring on the inner and outer surfaces when the round tube T0 is bent or shaped.

The check 4 liquid-tightly closes the upstream end opening of the round tube T0, and is gripped by a hydraulic or electric cylinder or the like (feeding means/not shown) to push out the round tube T0 downstream.

(2) Bending and Forming The round tube T0 filled with liquid is extruded downstream from the check 4 and passes through the auxiliary roll 23, the second support roll 22, the first support roll 21 and the forming roll 11. becomes a square tube T1.

Here, the first support roll 21, the second support roll 22, and the auxiliary roll 23 support the round tube T0 along its axis (straight center line extending in the front-rear direction). On the other hand, the forming space s formed by the forming rolls 11 is located at a position displaced (translated and rotated) from its axis. This displacement causes the round tube T0 to bend with the first support roll 21 as a starting point. The round tube T0 is pushed by the forming rolls 11 on the outer peripheral surface while being in a specific stress state due to the bending, and is plastically deformed to become the square tube T1.

As shown in FIG. 2, the forming rolls 111 to 114 can be driven in a direction (normal direction of the outer peripheral surface) in which the outer peripheral surface of the round tube T0 is pushed radially inward. Further, the entire molding roll 11 (molding space) has vertical parallel movement (L1), horizontal parallel movement (L2), vertical rotational movement (θ1), horizontal rotational movement (θ2 ) is possible. Thus, the forming rolls 11 can be translated or rotated in a plurality of directions, and the size and orientation of the forming space s formed by the forming rolls 11 can be changed in various ways.

《Drive controller》
A drive control device M (simply referred to as “device M”) for the forming roll 11 is illustrated in FIG. 3A (front view) and FIG. 3B (side view). FIG. 3A and FIG. 3B are collectively referred to as FIG. In addition, the same reference numerals are attached to the members and the like that have already been described, and the description thereof has been omitted as appropriate. In addition, reference numerals are mainly used for representative drawings or members, and reference numerals for similar members are omitted as appropriate.

The apparatus M comprises a base 100 fixed to the floor or the like, a lift table 101 vertically moved (L1) with respect to the base 100 by a drive mechanism 131, and a drive mechanism 132 horizontally moving the lift table 101 horizontally. The outer frame 102 moves (L2), the middle frame 103 rotates (θ2) around the up/down (vertical) axis with respect to the outer frame 102 by the driving mechanism 133, and the driving mechanism 134 moves left and right (horizontal) with respect to the middle frame 103. ) Drive mechanisms 121 to 124 (collectively referred to as “drive Mechanism 12"). The forming roll 11 and the driving mechanism 12 (push means) are arranged inside the inner frame 104 . Forming means and bending means in the present invention are realized by the forming rolls 11 and the drive control device M. As shown in FIG.

The drive mechanisms 12, 131, and 132 include linear motion mechanisms (for example, worm gears, feed screws, etc.) with speed reducers and servo motors as their drive sources. The drive mechanisms 133 and 134 are provided with a rotation mechanism with a speed reducer and a servomotor as its drive source. Each drive mechanism (particularly a servomotor) can be individually controlled by a computer executing a control program.

The device M further includes connecting slide blocks 141-144 (collectively referred to as "blocks 14") arranged side by side with the drive mechanisms 121-124. Interlocking of adjacent forming rolls 11 is realized by blocks 14 (interlocking members). For example, the connecting slide block 141 moves the adjacent forming roll 113 upward in conjunction with the upward movement of the forming roll 111 by the drive mechanism 121 . Since the connecting slide block 141 slides with respect to the drive mechanism 123 , it does not hinder the lateral movement of the forming roll 113 . A rectangular molding space s is stably formed by such blocks 14 .

<<Analysis example>>
Assuming a case where a square tube is formed from a round tube using the apparatus D as described above, the cross section of the obtained square tube was obtained by CAE (computer-aided engineering) analysis.

The case of molding a round pipe (base pipe) of φ50.8 mm × t1.2 mm into a square pipe with an outer cross section of 38 mm × 38 mm was analyzed using impact and structural analysis software LS-DYNA (manufactured by JSOL Co., Ltd.). . At this time, the forming space formed by the forming rolls had the same shape as the cross section of the square tube, and the center position of the forming space was 33 mm above the axis of the round tube (that is, the amount of lifting of the entire forming rolls: 33 mm). The analysis was performed in a state in which the pipe was not filled with liquid (no internal pressure).

FIG. 4 shows the cross section (analysis result) of the square tube formed from the round tube in this way. As is clear from FIG. 4, according to the manufacturing method of the present invention, the cross section of the bent square tube (radius of curvature: 664 mm) has a deviation of 1 mm or less from the target cross section.

For comparison, a cross section of a square tube (curvature radius: 763 mm) obtained by bending a 38 mm x 38 mm square tube (base tube) with the entire forming roll pushed upward by 44 mm was also obtained. The analysis results are also shown in FIG. In this case, it was found that although the amount of lift was increased by 11 mm, the radius of curvature increased, and the shape of the cross section greatly deviated from the target cross section, resulting in significant shape collapse. If the radius of curvature is made approximately the same as in the case of molding a square tube from a round tube, it is considered that the shape collapse will be further increased.

From the above, it was confirmed that by forming a blank pipe with bending, it is possible to efficiently manufacture a pipe material having a desired cross section while suppressing the collapse of the cross section.

T0 round pipe (raw pipe)
T1 square tube D tube material manufacturing device M drive control device 11 forming roll (forming means)
21 support roll (support means)

Claims (16)

A bending step of bending a blank pipe, which is a tubular material having a closed cross section;
a forming step of plastically deforming the bent base pipe to obtain a formed pipe having a closed cross section different from that of the base pipe;
A method for manufacturing a pipe material comprising: 2. The method of manufacturing a pipe member according to claim 1, wherein said bending step and said forming step are performed by filling said blank pipe with an incompressible fluid. The base pipe is a round pipe having a substantially annular closed cross section,
3. The method of manufacturing a pipe material according to claim 1, wherein the formed pipe is a rectangular pipe having a closed cross-section of a substantially rectangular annular shape. 4. The method for manufacturing a pipe material according to claim 1, wherein the formed pipe is a deformed pipe in which at least one of cross section, wall thickness, material, and characteristics changes in the longitudinal direction. 5. The method of manufacturing a pipe member according to claim 1, wherein the molded pipe has portions in which at least one of thickness, material, and properties are different in the circumferential direction. 6. The method for manufacturing a pipe member according to claim 1, wherein the closed cross section of the blank tube and the closed cross section of the formed tube have substantially the same outer peripheral length at corresponding positions before and after forming. 7. The method for manufacturing a pipe member according to claim 1, wherein the molded pipe has portions in which at least one of bending direction and curvature differs in the longitudinal direction. a feeding means for longitudinally moving a blank tube, which is a tubular material having a closed cross section;
a support means for supporting the raw pipe while moving the raw pipe in the longitudinal direction;
Bending means for bending the blank tube downstream of the support means;
forming means for plastically deforming the bent blank pipe into a shaped pipe having a closed cross-section different from that of the blank pipe;
A pipe material manufacturing device comprising: 9. The pipe material manufacturing apparatus according to claim 8, wherein said support means comprises at least a pair of opposing support rolls in contact with said raw pipe. 10. The pipe material manufacturing apparatus according to claim 9, wherein the support rolls are arranged in at least two rows along the longitudinal direction of the raw pipe. 11. The method of manufacturing a pipe member according to claim 8, wherein said bending means can change at least one of bending direction and curvature according to movement of said blank pipe. 12. The method of manufacturing a pipe member according to claim 8, wherein the forming means can change at least one of the shape and inclination of the forming space through which the raw pipe passes according to the movement of the raw pipe. The pipe material manufacturing apparatus according to any one of claims 8 to 12, wherein the forming means includes at least two pairs of forming rolls that are in contact with and surround the bent raw pipe. The forming tube is a rectangular tube having a substantially rectangular annular closed cross section,
The forming means includes four forming rolls that are in contact with and surround the raw pipe,
a pushing means for pushing each of the forming rolls to the inside of the blank tube;
The pipe material manufacturing apparatus according to any one of claims 8 to 13, comprising: 15. The tube material manufacturing apparatus according to claim 14, further comprising an interlocking member for sliding a forming roll adjacent to the forming roll in the direction of the pushing movement in conjunction with the pushing movement of the forming roll. 16. The pipe material manufacturing apparatus according to any one of claims 8 to 15, wherein said bending means and said forming means are integrated.

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