TW201313353A - Press forming method - Google Patents

Abstract

This press forming method uses a multiple-spindle press machine which independently activates multiple spindles so as to extrude a bottom portion of a concaved portion of a material and form a hollow shaft and includes: a first process of setting the material on a concave die; and a second process of pushing an end face of a side wall toward an axial direction of the first tool at a first velocity Vi by using a first tool, the side wall defining the concave portion of the material and forming a cylindrical shape, and simultaneously extruding the bottom portion of the material by using a second tool toward an axial direction of the second tool at a second velocity Vb, wherein a ratio Vb/Vi is controlled in a range of 0.7 to 1.5 in the second process.

Description

Press forming method Field of invention

The present invention relates to a press forming method for materials.

The case is based on the Japanese Patent Application No. 2011-145903, which was filed on June 30, 2011 in Japan, and its contents are cited in this case.

Background of the invention

A method of forming a cylindrical container having a bottom and a constant diameter or a multilayer cylindrical product having gradient portions having different diameters in the middle generally employs a method of further deep-drawing the cup-shaped intermediate material. For example, Non-Patent Document 1 discloses a re-deep processing method in which a disc-shaped material is formed into a cup-shaped intermediate material in a first step and a re-twisting process is performed in a second step.

In the processing method, the cup-shaped intermediate material formed in the first step is sandwiched between the pressing member inserted into the inner surface of the cylindrical tool and the mold, and the punching of the inner portion of the pressing member is performed. The head is inserted into the annular inner surface of the mold, and a cylindrical projection is formed at the bottom of the cup-shaped intermediate material. In such a molding method, there is a problem that the inflow of the material from the cup-shaped intermediate material to the inner surface of the punch and the cylindrical inner surface of the mold is insufficient, and the molding failure such as material breakage at the tip end portion of the punch is likely to occur.

In order to solve such a problem, Patent Document 1 and Patent Document 2 disclose that the cup is actively pushed into the cylindrical shape of the mold by using the divided mold. A method of preventing formation defects due to material breakage or the like. Further, Patent Documents 3 and 4 disclose related technologies.

Advanced technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open No. Hei 8-150426

Patent Document 2 Japanese Patent Laid-Open Publication No. 2002-113528

Patent Document 3 Japanese Patent Laid-Open No. Hei 8-141662

Patent Document 4 Japanese Patent Laid-Open No. Hei 6-210363

Non-patent literature

Non-Patent Document 1 Chang Tian Xiu, Liu Benrun: Plastic Processing from Basic Understanding, (1999), p.195, CORONA Press

Summary of invention

However, in the above-described deep drawing forming method, the method disclosed in Patent Document 1 tends to be complicated in the configuration of the mold because it is a forming method using hydraulic pressure. Further, since the direction in which the cup is pushed into the inner surface of the mold is opposite to the direction in which the punch is pushed in, it is not possible to sufficiently push it in.

According to the method disclosed in Patent Document 2, when the bottom portion of the intermediate material formed into a cup shape is subjected to deep drawing by a movable punch, a tool inserted into the inner surface of the side wall surface in a state of being sandwiched by the side wall is disposed and arranged The movable tool on the outer side of the outer wall surface is slidably coupled with the intermediate material in conjunction with the movable punch. Thereby, the side wall material of the intermediate material is actively fed into the inner surface of the mold to prevent material breakage at the tip end portion of the punch of the molded article. however, Since a gap is generally provided between the actual cup-shaped intermediate material side wall surface and the tool for which the side wall is to be pressed from the inner and outer sides, in many cases, the material cannot be sufficiently fed toward the inner surface of the mold of the target intermediate material side wall. Further, since the mold is divided, there is a problem that the angular portion at the end of the contact surface between the mold and the material is likely to be cracked.

According to Patent Document 3, in order to make the wall thickness of the product after deep drawing more uniform, a step of increasing the thickness such as imprinting or shaft compression processing is additionally applied in the middle of the forming step, so that the depth of use is deep. A method of forming a thinned portion by punch forming can increase the wall thickness. However, in such a method, since only a single step of the step of increasing the wall thickness is performed, there is a problem that the productivity is lowered and the manufacturing cost is increased. Moreover, this method is a method of forming a thicker wall after deep drawing processing for the purpose of improving the wall thickness precision of the shaped product. That is, such a method is difficult to achieve the object of the present invention to prevent formation failure due to material breakage or the like in deep drawing.

For example, Patent Document 4 discloses that the correspondence between the thinned portion of the wall thickness after forming and the position of the material is investigated in advance, and then the material portion corresponding to the thinned portion after deep drawing is compared with other portions, and The wall thickness is relatively thickened to perform machining, and the material subjected to the machining is subjected to deep drawing processing. However, such a method requires that all the materials to be formed must be machined into a predetermined size and shape by machining such as cutting or grinding, which may cause an increase in cost and a decrease in production efficiency.

The present invention is directed to such a problem, and an object of the present invention is to provide a hydraulic system in which a split mold or a mold having a complicated mold is not used. Under the deep drawing method in which the material during molding is less likely to crack.

In order to solve the above problems and achieve the project, the present invention adopts the following means.

(1) A press forming method according to an aspect of the present invention is a multi-axis pressing device which can independently operate a plurality of axes, and pushes a bottom portion of the recessed portion of the material in which the recess is formed, and then extends the processed hollow shaft; The first step and the second step are included, wherein the first step is to attach the material to the concave mold; and the second step is to form the cylindrical side wall by dividing the concave portion of the material by the first tool. The end surface is pushed in the axial direction of the first tool at the first speed Vi, and the bottom portion of the material is pushed out at the second speed Vb by the second tool in the axial direction of the second tool; In the second step, the ratio (Vb/Vi) of the second speed Vb to the first speed Vi is controlled to be in the range of 0.7 to 1.5.

(2) The press molding method according to the above (1), wherein the second step further uses a third tool provided between the first tool and the second tool to perform a pressing of the material; The thickness of the material before the second step is t, and the sum of the gap s1 between the outer peripheral surface of the material and the inner peripheral surface of the concave mold, and the gap s2 between the inner peripheral surface of the material and the outer peripheral surface of the third tool When s is set, the following conditional expression (a) can also be satisfied: 0.02 × t ≦ s ≦ 0.3 × t... (a)

By using the present invention, it is possible to prevent the material from being cracked. In the case, deep drawing is performed stably.

Simple illustration

Fig. 1A is a cross-sectional view showing an example of a mold used in the embodiment.

Fig. 1B is a cross-sectional view showing an example of a mold used in the embodiment.

Fig. 1C is a cross-sectional view showing an example of a mold used in the embodiment.

Fig. 2 is a schematic view showing the crack of the tip end corner portion of the punch which is intended to improve the problem in the embodiment.

Fig. 3A is a state diagram before the inside of the mold is filled with the material in the embodiment.

Fig. 3B is a view showing a state in which the inside of the mold is filled with the material in the embodiment.

Form for implementing the invention

The press forming method of the present embodiment will be described in detail below using the drawings. In the present embodiment, the cup-shaped material 6 is used for the material in which the recess has been formed, and the cup-shaped material 6 is molded. Fig. 1A to Fig. 1C are schematic views showing a mold (pressing die) 100 of the multiaxial pressing device used in the present embodiment. The mold 100 shown in FIGS. 1A to 1C is provided at a predetermined position of the multi-axis pressing device provided with the plurality of shafts capable of independently operating, and further includes: a cylindrical punch 1 and a pressing member 2. This punch 1 pushes out the inner bottom of the cup-shaped material 6. The pressing member 2 is in the shape of a cylinder covering the periphery of the punch 1, and the inner surface of the cup-shaped material 6 is pressed by the outer peripheral surface during the forming process. The punch 1 is a rod-shaped punch that is pushed out toward the material discharge side (below the paper surface) of the mold 4 on the inner bottom portion of the cup-shaped material 6 disposed on the mounting side (described above) of the mold 4 (described later). In the press forming method of the present embodiment, the bottom of the cup-shaped material 6 is pushed out by the above-described multi-axis pressing device, and the stretching process is performed in the middle. Empty shaft.

In addition, the outer diameter of the material used is preferably 20 mm to 300 mm. If the outer diameter is less than 20 mm, it is difficult to push out the bottom of the cup-shaped material 6 and extend it into a hollow shaft. Further, when the outer diameter exceeds 300 mm, the mold becomes large, and the forming load also increases, resulting in the necessity of a large press or the like, which makes practical molding difficult. More preferably 50mm~120mm.

Further, the material thickness (wall thickness) of the material is preferably set to 1.5 mm to 15 mm. If it is less than 1.5 mm, the pushing of the end face of the material side tends to be difficult; on the other hand, if it exceeds 15 mm, the formation of the cup-shaped intermediate material tends to be difficult. More preferably 2mm~12mm.

Further, the mold 100 used in the present embodiment has a cylindrical outer peripheral punch 3 which is annular in shape so as to surround the periphery of the binder 2. The outer peripheral punch 3 has a projection 3a. The projection 3a is placed on the upper edge of the opening of the cup-shaped material 6 disposed on the material mounting side of the mold 4, and is pushed toward the material discharge side of the mold 4. Further, the mold 100 of the present embodiment has a substantially annular shape mold 4 and a reverse punch 5. The mold 4 presses the material 6 between the falling punch 1 while pressing the bottom of the cup-shaped material 6, and is decorated to have a predetermined size. The reverse punch 5 is inserted into the inner surface of the cylindrical mold 4, and the bottom surface of the material is pressed between the punch 1.

Further, the mold 100 is composed of a convex mold and a concave mold. The convex mold system includes: a punch 1, a pressing member 2, and a peripheral punch 3; the concave mold includes a mold 4 and a reverse punch 5.

Further, the multi-axis pressing device of the present embodiment is provided with the movement of the punch 1, the binder 2, the outer peripheral punch 3, and the reverse punch 5, and can be individually A drive mechanism (not shown) that controls independently. Each of the members of the molds 100 is controlled by the press machine (not shown) according to the present embodiment, and the material 6 is controlled to have a predetermined size.

Next, the behavior of each member will be described with respect to the press forming method using the mold 100 shown in FIGS. 1A to 1C. First, the punch 1, the binder 2, and the peripheral punch 3 are raised to a sufficient height to insert the cup-shaped material 6 with the mold 4 by the drive mechanism control of the press. In this state, the cup-shaped material 6 is placed (mounted) on the upper side of the mold 4 in a state in which the central axis of the inner circumference of the mold 4 is slightly aligned with the central axis. Then, the punch 1, the binder 2, and the outer peripheral punch 3 are integrally formed, and are lowered while being controlled by the driving mechanism of the press. When the binder 2 and the punch 1 come into contact with the bottom surface of the material 6, and the outer peripheral punch 3 comes into contact with the upper edge surface of the cup-shaped material 6, the lowering operation is stopped (see Fig. 1A).

Further, at this time, the reverse punch 5 rises along the inner surface of the cylindrical mold 4 at the same time as the movement of the tools. When the reverse punch 5 comes into contact with the bottom surface of the material 6, the above-described ascending operation is stopped (see Fig. 1A). In a state where the operation of each member of the mold up to this point is completed, the cup-shaped material 6 is pressed between the pressing member 2 and the mold 4, the punch 1 and the reverse punch 5, and is fixed in the mold 4.

As described above, in a state in which the cup-shaped material 6 is fixed in the mold 4, the bottom of the material 6 is pushed out while the punch 1 is lowered while the binder 2 is stopped. Further, in conjunction with the operation of the punch 1, the reverse punch 5 also descends. By this action, a cylindrical projection having a diameter smaller than the outer diameter of the material 6 is formed at the bottom of the cup-shaped material 6 (see FIG. 1B). In the forming In the middle, the outer peripheral punch 3 is lowered by the lowering of the punch 1, and the upper edge surface of the opening of the material 6 is pressed to promote the inflow of the material 6 into the inside of the mold 100, that is, to facilitate the flow into the mold 4 and the reverse punch. 5. The area between the punch 1, the binder 2, and the outer peripheral punch 3 flows into the material discharge side (see FIG. 1B and FIG. 1C). By this action, as shown in Fig. 2, the material breakage at the tip end portion of the punch is prevented.

When the peripheral punch 3 is lowered, in order to prevent the material from being broken at the tip end portion of the punch, the ratio of the lowering speed Vi to the descending speed Vb of the punch 1 is controlled to be in the range of Vb/Vi = 0.7 to 1.5. The reason why the falling speed Vi of the outer peripheral punch 3 and the lowering speed Vb of the punch 1 are important factors in preventing the material 6 from being broken at the front end of the punch during the molding is as follows. In the press forming method of the present embodiment, the outer peripheral punch 3 is used for forming, and the upper edge of the cup-shaped material 6 is pressed to promote the inflow of the material into the inside of the mold 100, so that the material can be stably formed without being broken. Therefore, when the ratio of the descending speed of the outer peripheral punch 3 and the punch 1 is not appropriate, the effect that the material 6 sufficiently flows into the inside of the mold 100 cannot be obtained, and for example, the breakage shown in Fig. 2 may occur. The reason why the effect of the material 6 sufficiently flowing into the inside of the mold 100 cannot be obtained, and it is considered that it is disposed between the cup-shaped material 6 disposed at a predetermined position of the mold 4, between the mold 4, and between the material 6 and the pressing member 2 before molding. The effect of the gap.

The reason why the above-described inflow effect cannot be obtained will be described with reference to FIGS. 3A and 3B. In the state shown in Fig. 3A, the punching member 1, the pressing member 2, and the outer peripheral punch 3 are in contact with each other at the moment when the material 6 is attached to the material mounting side of the mold 4 (however, the pressing force applied to the material 6 is set to be Weakly negligible Force) map. Moreover, FIG. 3B is a state diagram in which the material 6 is filled inside the mold 100.

Here, the behavior of the multiaxial pressing device will be described with respect to the state from the state of FIG. 3A to the state of FIG. 3B. As shown in FIG. 3A, when the material 6 is mounted in the mold 100, a gap in the horizontal direction is formed between the material 6 and the binder 2, and between the material 6 and the mold 4. From this state, when the upper edge of the material 6 is pressed by the outer peripheral punch 3, the upper end portion of the material 6 is subjected to compressive stress by the pressing of the outer peripheral punch 3. By the propagation of the stress, the material 6 is strained, and the shape of the material 6 is changed in accordance with the gap in the buried installation. Then, in the state of FIG. 3B, the outer wall of the material 6 and the inner wall of the inside of the mold 100 are in full contact with each other, that is, the inside of the mold 100 is filled with the material 6.

The reason why the gap is designed between the material 6 and the binder 2 and the mold 4 when the material 6 is installed (at the time of mounting) will be described. This gap is designed such that the material 6 can be easily and conveniently placed at a predetermined position inside the mold 100. If there is no gap between the material 6 and the mold 4, when the material 6 is attached to the mold 100, the material 6 and the mold 4 are fitted before the predetermined position, and there is a possibility that the material 6 can no longer be pushed. . Therefore, the material 6 cannot be moved to a predetermined position in the mold 100. Further, when the material 6 that cannot be moved is forcibly moved, there may be a problem that the material 6 or the mold 100 is defective.

Furthermore, on the other hand, the gap between the material 6 and the pressing member 2 is such that the pressing member 2 can be easily inserted into the inner surface of the cup-shaped material 6 at the start of forming, and the pressing member 2 and the material 6 are prevented. Designed for the purpose of embarrassment.

When the gap is provided between the respective members of the mold and the material 6, when the outer peripheral punch 3 is pressed against the upper edge of the cup-shaped material 6, the punch 1 is lowered and deep-drawn, according to The ratio of the lowering speed of the outer peripheral punch 3 to the lowering speed of the punch 1 may cause the outer peripheral punch 3 to press the upper edge of the material 6 without sufficiently obtaining the purpose of the press forming method of the present embodiment, so that the material 6 flows in. The effect inside the mold 100 causes the material 6 to break. The reason is that in the state where there is a gap between the material 6 and the tool such as the mold 4 and the pressing member 2, when the upper edge of the material 6 is pressed by the outer peripheral punch 3, the falling speed and the punching according to the outer peripheral punch 3 are used. The ratio of the descending speed of the head 1 and the pushing effect are lower than the promoting material 6 for the purpose of the embodiment, and the material 6 is consumed in the gap between the mold 4 and the pressing member 2 and the like. As a result, the effect of the pressing by the outer peripheral punch 3 is not sufficient to prevent the breakage of the material 6 from contributing.

In the press forming method of the present embodiment, in order to prevent such a problem, when the outer peripheral punch 3 is lowered, the descending speed is controlled to an appropriate value. That is, in the press forming method of the present embodiment, the lowering speed Vi of the outer peripheral punch 3 is controlled in a range of Vb/Vi = 0.7 to 1.5 in accordance with the ratio of the lowering speed Vb of the punch 1. By setting Vb/Vi to the above range, it is possible to sufficiently ensure that the material 6 is poured into the mold 4 by the pressing of the outer peripheral punch 3, and the material is formed without breaking the material.

When the ratio Vb/Vi of the falling speed Vi of the peripheral punch 3 to the falling speed Vb of the punch exceeds 1.5, the falling speed of the punch 1 is excessively large with respect to the falling speed of the outer peripheral punch 3, and the pushing of the punch 1 is relatively large. The feeding amount of the material 6 by the peripheral punch 3 toward the inside of the mold 100 may be insufficient, resulting in failure to charge. The material is prevented from being broken at the tip end corner of the punch 1.

Further, when Vb/Vi is less than 0.7, the material 6 to be pushed by the outer peripheral punch 3 is excessively pushed, which causes a problem in the manufacture of a product such as a burr occurring between the outer peripheral punch 3 and the mold 4. The above range is irrelevant whether or not the material is filled inside the mold 100.

Here, in the state shown in FIG. 3A (that is, the state before the upper edge of the material 6 is pressed by the outer peripheral punch 3), the thickness of the material 6 is set to t, and the material 6 and the mold 4 are formed. The gap (horizontal direction gap) is set to s1, and a gap (horizontal direction gap) formed between the material 6 and the binder 2 is set to s2. When the sum of s1 and s2 is set to s, it is preferable to satisfy 0.02 × t ≦ s ≦ 0.3 × t. By satisfying the above-described conditions by the total thickness s of the thickness t and the gap, it is possible to more reliably obtain the effect of the speed ratio of the lowering speed Vi of the outer peripheral punch 3 and the lowering speed Vb of the punch as described above. Even if the total gap s is not in the above range, the forming can be completed without breaking and burrs. However, when the total gap s is less than 0.02t, the inner surface of the cup-shaped material 6 cannot be provided inside the mold 100 before the molding, and the pressing member 2 is smoothly inserted, resulting in the occurrence of a depression in the upper edge surface of the material 6. Or a case where a part of the side wall is thinned. Further, if the total gap s exceeds 0.3 t, since the gap is excessively large, if the upper edge of the cup-shaped material 6 is pushed down by the outer peripheral punch 3 after the presser 2 is inserted, the side wall of the material 6 may be bent. The shape of the molded article is poor. Therefore, when higher forming precision is required, the sum of gaps s preferably satisfies 0.02 × t ≦ s ≦ 0.3 × t.

Whether or not the relevant material 6 is filled with the mold is pre-formed according to the same material and the setting conditions of the multi-axis pressing device, and for example, a mold is obtained. According to this relationship, the relationship between the control position of each member and the fullness of the material toward the inside of the mold can be determined according to the position of the mold. More specifically, the molding is performed under different conditions (Vb/Vi conditions), and the experiment is completed in the middle of the forming, and the punches in which the multi-axis pressing device starts driving until the end of the forming are recorded under the respective conditions. 1 stroke amount. Then, by measuring the cross-sectional shape of the formed material, and learning the relationship between the shape of the mold and the shape of the mold by using the mold pattern describing the detailed size and shape of the mold, the material can be fully charged, and the rush from the start of driving can be used. The amount of stroke of the head 1 is experimentally obtained in advance for the timing of changing the speed ratio.

It is determined whether or not the material 6 is filled with a mold, and a method other than the above may be used. For example, if the material 6 is filled with the mold, the load applied to the peripheral punch 3 will increase. Therefore, it is also possible to install a load cell on the peripheral punch 3, and then use the load change to judge whether or not there is fullness.

Example (Example 1)

Using a multi-axis pressing device shown in Figs. 1A to 1C, a carbon steel cup-shaped material having an outer diameter of φ 90 mm × a wall thickness of 2 mm × a height of 30 mm is formed into an outer diameter at room temperature while maintaining a wall thickness of 2 mm. Φ50mm cup. In this molding, the multi-axis pressing device is set to be used before and after the filling of the inside of the mold by the pre-forming (before filling and after filling), and in either case, the falling speed Vi of the outer peripheral punch 3 is set, and the rushing is performed. The ratio of the descending speed Vb of the head, Vb/Vi, is in the same value state. Table 1 shows the relationship between the speed ratio Vb/Vi and the forming result in the forming.

When the speed ratio Vb/Vi is in the range of 0.7~1.5, the material is not Forming occurs in the event of breakage and burrs. On the other hand, when the speed ratio Vb/Vi is smaller than 0.7, the material may have a burr which constitutes a problem in the manufacture of the product. Further, when the speed ratio Vb/Vi is larger than 1.5, the forming is interrupted because the material during the forming is broken.

(Example 2)

Using a multi-axis pressing device shown in Figs. 1A to 1C, an aluminum cup-shaped material having an outer diameter of φ 120 mm × a wall thickness of 5 mm × a height of 40 mm was formed into an outer diameter at room temperature while maintaining a wall thickness of 5 mm. Φ 70mm cup. In this molding, the multi-axis pressing device is set such that the ratio Vb/Vi of the lowering speed Vi of the outer peripheral punch 3 and the lowering speed Vb of the punch is made before and after the filling of the inside of the mold is filled by the pre-forming material. Different value states. Table 2 shows the relationship between the speed ratio Vb/Vi and the forming result of the multiaxial pressing device which is formed during the forming.

In the case where the speed ratio Vb/Vi is in the range of 0.7 to 1.5 before and after the filling, the forming can be completed without breaking or burrs of the material. On the other hand, when the speed ratio Vb/Vi of any of the conditions before and after the filling is less than 0.7, the material is formed into a product. Make a problem with the raw edges. Further, when the speed ratio Vb/Vi before any of the filling and the filling is greater than 1.5, the material is broken during the forming, and the forming is interrupted.

(Example 3)

Further, using a multi-axis pressing device shown in Figs. 1A to 1C, a carbon steel cup-shaped material having an outer diameter of φ 80 mm × a wall thickness of 5 mm × a height of 45 mm was formed at room temperature while maintaining a wall thickness of 5 mm. It is a cup with an outer diameter of 45 mm. Table 3 shows the relationship between the total amount s of the material 6 in the molding and the mold 4 and the pressing material 2, and the forming result.

The gap in Table 3 is the sum s of the gap (horizontal direction gap) formed between the material 6, the mold 4, and the pressing member 2 in the state shown in Fig. 3A, divided by the value of the material thickness thickness t of the material 6. .

In the case where the speed ratio Vb/Vi is in the range of 0.7 to 1.5 before and after the filling, the forming can be completed without breaking or burrs of the material. On the other hand, when the speed ratio Vb/Vi of any of the conditions before and after the filling is less than 0.7, the material may have a burr which constitutes a problem in the manufacture of the product. Further, when the speed ratio Vb/Vi before any of the filling and the filling is greater than 1.5, the material is broken during the forming, and the forming is interrupted.

Further, when the total gap s is smaller than 0.02 times the thickness of the material plate, the pressing of the pressing member may occur; when the gap is larger than 0.3 times the thickness of the material 6, the side wall of the material 6 may be bent. On the other hand, when the total gap s is in the range of 0.02 times to 0.3 times the thickness t of the material plate, such a press member insertion failure and the material side wall bending do not occur, and molding with higher precision can be performed.

(industrial availability)

The press forming of the present invention allows for deep drawing formation in a stable manner without cracking of the material. Therefore, the value of industrial use is quite high.

1‧‧‧ Punch

2‧‧‧Pressure parts

3‧‧‧ peripheral punch

3a‧‧‧Protruding

4‧‧‧Mold (concave mold)

5‧‧‧Reverse punch

6‧‧‧materials

100‧‧‧Mold

Fig. 1A is a cross-sectional view showing an example of a mold used in the embodiment.

Fig. 1B is a cross-sectional view showing an example of a mold used in the embodiment.

Fig. 1C is a cross-sectional view showing an example of a mold used in the embodiment.

Fig. 2 is a schematic view showing the crack of the tip end corner portion of the punch which is intended to improve the problem in the embodiment.

Fig. 3A is a state diagram before the inside of the mold is filled with the material in the embodiment.

Fig. 3B is a view showing a state in which the inside of the mold is filled with the material in the embodiment.

1‧‧‧ Punch

2‧‧‧Pressure parts

3‧‧‧ peripheral punch

3a‧‧‧Protruding

4‧‧‧Mold (concave mold)

5‧‧‧Reverse punch

6‧‧‧materials

100‧‧‧Mold

Claims (2)

A press forming method adopts a multi-axis pressing device capable of independently operating a plurality of shafts, and pushes out the bottom of the recessed portion of the material forming the recess, and then extends the processing to a hollow shaft, which is characterized by comprising the following steps: In the first step, the material is attached to the concave mold; and in the second step, the end surface of the side wall of the cylindrical shape is defined by the first tool by the first tool toward the first tool The axial direction is pushed in at the first speed Vi, and the second tool is used to push the bottom of the material toward the axial direction of the second tool by the second speed Vb. The second step is the second step. The ratio Vb/Vi of the second speed Vb to the first speed Vi is controlled to be in the range of 0.7 to 1.5. The press forming method according to claim 1, wherein the second step further uses a third tool provided between the first tool and the second tool to perform a pressing of the material; The thickness of the material before the two steps is t, and the sum of the gap s1 between the outer peripheral surface of the material and the inner peripheral surface of the concave mold, and the gap s2 between the inner peripheral surface of the material and the outer peripheral surface of the third tool is In the case of s, the following conditional expression (1) is satisfied: 0.02 × t ≦ s ≦ 0.3 × t (1).