Method for forming sidewall portion

Abstract

In a method for integrally forming a product having a top plate portion and a side wall portion erected from an end portion from a plate-shaped material made of a general material by pressing at room temperature, a top plate portion of an intermediate material having a top plate portion and a side wall portion integrally formed by bending an end portion of the material at a predetermined first angle is clamped, and the side wall portion of the intermediate material, which has been opened by springback and whose flange angle, which is the angle between the top plate portion and the side wall portion, is larger than the first angle, is pushed back until the flange angle coincides with the first angle while maintaining this state, and thereby the tip end of the side wall portion of the intermediate material is pressed toward the base end side. This eliminates or reduces springback without performing an additional process of a step forming process, which is a process of pushing the side wall portion until the angle between the top plate portion and the side wall portion becomes smaller than the desired angle.

Description

[Technical field]

[0001] The present invention relates to a method for forming a sidewall portion. [Background technology]

[0002] For example, when a product 200 having a top plate 210 and a side wall (flange) 220 erected at a substantially right angle from an end of the top plate 210 is integrally formed by pressing a plate-like material (not shown), a "bending process" is generally performed, which is a process for forming the side wall by bending and / or drawing. Fig. 2(a) is a schematic cross-sectional view showing an example of such a bending process. However, Fig. 2 shows only a portion of one side wall 220 of the product 200 that is formed by the bending process, not the entire material 100.

[0003] 2(a), an end of a plate-shaped material 100 sandwiched between the first lower die 11 and the first pad 21, protruding from between the first lower die 11 and the first pad 21, is bent at a substantially right angle by a first bending blade 31 driven in the direction of the white arrow shown in the figure. As a result, a first intermediate material 110 having an integrally formed side wall portion is manufactured.

[0004] However, as illustrated on the right side of FIG. 2(a), when the first intermediate material 110 is removed from the mold after the completion of the bending process, the side wall portion opens due to springback, and the angle between the top plate portion and the side wall portion (hereinafter, sometimes referred to as the "flange angle") may become larger than an approximately right angle. For this reason, a process called a "rise forming process" is widely performed as an additional process so that the flange angle becomes approximately a right angle as a result of the side wall portion opening due to springback after the bending process. The rise forming process is a process in which the amount of springback is offset by pressing the side wall portion until the flange angle reaches the rise forming angle, which is an angle (acute angle) smaller than a right angle by an angle corresponding to the angle at which the side wall portion opens due to springback (hereinafter, sometimes referred to as the "springback amount").

[0005] FIG. 2(b) is a schematic cross-sectional view showing an example of the above-mentioned overhang forming process. In the example shown in FIG. 2(b), the side wall of the first intermediate material 110, in which the top plate portion is sandwiched between the second lower die 12 and the first pad 21, and the angle of the corner facing the bent portion (boundary portion between the top plate portion and the side wall portion) of the first intermediate material 110 is an acute overhang forming angle, is pushed in by the second bending blade 32 driven in the direction of the white arrow shown in the figure. As a result, the second intermediate material 120 is manufactured in which the angle (flange angle) between the top plate portion and the side wall portion is an overhang forming angle (acute angle). However, as exemplified on the right side of FIG. 2(b), when the intermediate material 120 is removed from the mold after the overhang forming process is completed, the side wall portion opens due to springback, and the flange angle can become approximately a right angle.

[0006] However, since the amount of springback varies depending on, for example, the material constituting the blank, the shape of the product to be formed, and / or the processing conditions, etc., in order to set the angle of the edge forming appropriately, it is necessary to carefully estimate the amount of springback for each product. Even if the angle of the edge forming is set appropriately in this way, it is difficult to completely eliminate the variation between individual processed products in mass production. For this reason, a "edge cutting process" is widely used as an additional process in which the side wall is formed to be longer than the target shape while anticipating a certain degree of variation, and then the excess part is cut off from the side wall.

[0007] FIG. 2(c) is a schematic cross-sectional view showing an example of the above-mentioned edge cutting process. In the example shown in FIG. 2(c), the top plate portion is sandwiched between the third lower die 13 and the first pad 21, and the side wall portion is sandwiched between the third lower die 13 and the second pad 22. The excess portion located at the tip of the side wall portion of the intermediate material 120 is cut by the first punch 41 and the third lower die 13 driven in the direction of the white arrow shown in the figure. As a result, scrap 300 is cut from the tip of the side wall portion of the intermediate material 120, and the product 200 including the top plate portion 210 and the side wall portion 220 standing at a substantially right angle from the end of the top plate portion 210 and having a desired length as illustrated in FIG. 1 is integrally formed. However, cutting the scrap 300 in the edge cutting process as described above leads to a waste of resources and causes a deterioration in product yield.

[0008] 1, the thickness (dimension in the extending direction of the side wall portion) of the third lower die 13 used in the above-mentioned edge cutting process needs to be reduced. That is, since the third lower die 13 needs to be thinned according to the length required for the side wall portion 220 as in the product 200, it may be difficult to configure the third lower die 13 to have durability sufficient to withstand the stress and / or impact acting when the scrap 300 is cut off by the first punch 41.

[0009] On the other hand, Patent Document 1 (JP 2001-225111 A )and Patent Document 2 (JP Patent Publication 2014-91140A) disclose a method of constraining a material having a substantially U-shaped cross section with a side wall portion formed by bending and / or drawing inside a die, and performing a so-called "coining process" in which the tip of the side wall portion is struck (pressed) toward the base end side. This method is said to improve the dimensional accuracy of the tip shape of the side wall portion and to impart sufficient compressive residual stress to improve fatigue strength. However, this method does not take into consideration the problem that the side wall portion opens due to springback when the product is removed from the die after the bending process is completed, as described above, causing the flange angle to become larger than a predetermined angle (for example, a substantially right angle).

[0010] Furthermore, Patent Document 3 (JP Patent Publication 2014-221493 A) discloses a method for forming a box body having a top plate and a side wall portion erected from the top plate by multiple warm press processes from a metal plate made of a specific material such as magnesium. According to this method, it is possible to provide a box body having sharp corners by simultaneously performing bending and / or drawing and coining. However, this method also does not take into consideration the problem that the side wall portion opens due to springback when the product is removed from the mold after the bending process is completed, and the flange angle becomes larger than a predetermined angle (for example, approximately a right angle), as described above.

[0011] As described above, in this technical field, there is a demand for a technology that can eliminate or reduce springback in a method of integrally molding a product having a top plate portion and a side wall portion (flange portion) erected at a predetermined angle (e.g., approximately a right angle) from the end of the top plate portion by pressing a material made of a common material at room temperature, without performing the above-mentioned overhanging forming process as an additional process. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2001-225111 A [Patent Document 2] JP 2014-91140 A [Patent Document 3] JP 2014-221493 A Summary of the Invention [Problem to be solved by the invention]

[0013] As described above, in this technical field, in a method of integrally forming a product having a top plate portion and a side wall portion (flange portion) erected at a predetermined angle (for example, approximately a right angle) from the end of the top plate portion by pressing a plate-shaped material made of a common material at room temperature, there is a demand for a technology that can eliminate or reduce springback without performing the above-mentioned overhanging forming process as an additional process. [Means for solving the problem]

[0014] In consideration of the above problems, the inventor conducted extensive research and discovered that springback can be eliminated or reduced without performing an additional step of a step forming process, which is a process of pushing the side wall portion of the intermediate material toward the base end, while clamping the top plate portion of an intermediate material having a top plate portion and side wall portion formed integrally by bending the end of the material at a predetermined first angle, and pushing back the side wall portion of the intermediate material until the flange angle, which is the angle between the top plate portion and the side wall portion, of the intermediate material that has opened due to springback and become larger than the first angle, until the flange angle matches the first angle, while maintaining this state.

[0015] Specifically, the method for forming a side wall portion according to the present invention (hereinafter, sometimes referred to as the "method of the present invention") is a method for forming a side wall portion in a construction method in which a product including a top plate portion and a side wall portion erected at a first angle, which is a predetermined angle, from an end of the top plate portion is integrally formed from a plate-shaped material by pressing at room temperature. The method of the present invention includes the first to third steps listed below.

[0016] The first step is a step of obtaining an intermediate material having an integrally formed top plate portion and side wall portion by bending an end portion of the material at a first angle by bending and / or drawing.

[0017] The second step is a step of clamping the top plate portion of the intermediate material between a first holding member arranged on the outside of the top plate portion of the intermediate material and a second holding member arranged on the inside of the top plate portion of the intermediate material.

[0018] The third step is a step of changing the side wall portion of the intermediate material from the first state to the second state, and pressing the first end portion, which is the end portion on the tip side of the side wall portion of the intermediate material, toward the base end while maintaining the second state. The first state is a state in which the side wall portion of the intermediate material opens due to spring back and the flange angle, which is the angle between the top plate portion and the side wall portion of the intermediate material, is larger than the first angle. The second state is a state in which the side wall portion of the intermediate material is pushed back until the flange angle matches the first angle. Effect of the Invention

[0019] In the method of the present invention, as described above, in the third step, the side wall of the intermediate material is pushed back until the flange angle, which is the angle between the top plate and the side wall, becomes larger than the desired first angle due to springback, and the tip end of the side wall is pressed toward the base end while maintaining the side wall in the pushed-back state until the flange angle becomes the first angle. This eliminates or reduces the residual stress that causes springback in the intermediate material, and makes it possible to form a product whose flange angle matches the desired first angle.

[0020] In other words, according to the method of the present invention, in a process in which a product having a top plate portion and a side wall portion (flange portion) erected at a predetermined angle (for example, approximately a right angle) from the end of the top plate portion is integrally formed from a plate-shaped material made of a common material by press processing at room temperature, springback can be eliminated or reduced without performing the above-mentioned overhanging forming process as an additional process.

[0021] Other objects, features and attendant advantages of the present invention will become readily apparent from the following description of the embodiments of the present invention which are given with reference to the accompanying drawings. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic perspective view showing an example of a product having a top plate portion and a side wall portion erected at a substantially right angle from an end portion of the top plate portion. FIG. [Diagram 2] 1 is a schematic diagram showing an example of a conventional technique for forming a side wall portion erected at a substantially right angle from an end of a top plate portion. FIG. [Diagram 3] 4 is a flowchart illustrating the flow of each step included in the sidewall forming method (first method) according to the first embodiment of the present invention. [Figure 4] 4A to 4C are schematic diagrams illustrating changes in shape during the process of forming a plate-shaped material into a product having a top plate portion and side wall portions by the first method. [Diagram 5] FIG. 1 is a schematic diagram illustrating one specific means for obtaining an intermediate material having an integrally formed top plate portion and side wall portion by bending an end portion of the material at a first angle in a first step. [Figure 6] FIG. 11 is a schematic diagram illustrating one specific means for pushing back the side wall portion of the intermediate material in a first state to change it to a second state in the third step while pressing the tip end (first end) of the side wall portion toward the base end. [Figure 7] FIG. 11 is a schematic diagram illustrating a third step performed by advancing a punch having a predetermined shape in a first direction, which is a predetermined direction, in a side wall forming method (second method) according to a second embodiment of the present invention. [Figure 8] FIG. 11 is a schematic diagram illustrating a state in which at least a portion including a first end of a side wall portion of an intermediate material is contained inside a closed space in a third step included in a method for forming a side wall portion (third method) according to a third embodiment of the present invention, and the first end is pressed toward the base end side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] First Embodiment Hereinafter, a method for forming a sidewall portion according to a first embodiment of the present invention (hereinafter, may be referred to as a "first method") will be described.

[0024] <composition> The first method is a method for forming the sidewalls in a method for integrally forming a product having a top plate and a sidewall erected at a first angle, which is a predetermined angle, from a plate-shaped material by pressing at room temperature. The material constituting the material is not particularly limited as long as it is possible to obtain an intermediate material having a top plate and a sidewall integrally formed by bending the end by bending and / or drawing. Specific examples of such materials include metals such as stainless steel, copper, and aluminum, and alloys containing these metals. The shape of the material is not particularly limited as long as at least the parts that will become the top plate and the sidewalls are plate-shaped, and may be planar or curved, and there may be non-plate-shaped parts in areas other than the parts that will become the top plate and the sidewalls. Typically, the shape of the material is, for example, a rectangular, elliptical, or circular flat plate.

[0025] The number of side walls erected at the end of the top plate may be one or more. When there are more than one side walls, all of the side walls may be erected at the same first angle on the same side of the top plate, or some of the side walls may be erected at different first angles. In the latter case, some of the side walls may be erected facing the opposite side of the top plate from the other side walls. Furthermore, the first method can be applied to a method of forming a cylindrical product with a bottom by providing an annular side wall surrounding the periphery of the top plate.

[0026] The first method includes the first to third steps described below in detail, as shown in the flow chart illustrated in FIG. 3. In the following description, the details of each step included in the first method will be described with reference to FIG. 4 and FIG. 5 in addition to FIG. 3. FIG. 3 is a flow chart illustrating the flow of each step included in the first method, and FIG. 4 is a schematic diagram illustrating the change in shape during the molding process of a plate-shaped material into a product having a top plate portion and a side wall portion by the first method. However, as in FIG. 2 described above, FIG. 4 and FIG. 5 depict only a portion of one side wall portion 220 of the product 200 that is molded by the bending process, not the entire material 100.

[0027] As illustrated in Fig. 3, a first process is first performed in step S10. The first process is a process for obtaining an intermediate material having an integrally formed top plate portion and side wall portion by bending an end portion of the material at a first angle by bending and / or drawing. Specifically, for example, the end portion of a plate-shaped material 100 as illustrated in Fig. 4(a) can be bent at a predetermined first angle θ1 by bending and / or drawing as shown by the black arrow in Fig. 4(b).

[0028] FIG. 5 is a schematic diagram illustrating one specific means for obtaining an intermediate material 130 having a top plate portion 131 and a side wall portion 132 integrally formed by bending the end portion of the material 100 at a first angle θ1 in the first step as described above. First, as illustrated in FIG. 5(a), the plate-shaped material 100 is sandwiched between the first lower die 11 and the first pad 21. Next, as illustrated in FIG. 4(b) and FIG. 5(b), the end portion of the material 100 protruding from between the first lower die 11 and the first pad 21 is bent at a predetermined first angle θ1 by the first bending blade 31 driven in the direction of the white arrow shown in the figure (see the arrow hatched with oblique lines in FIG. 5(b)). As a result, as illustrated in FIG. 4(b) and FIG. 5(b), the intermediate material 130 having a top plate portion 131 and a side wall portion 132 integrally formed can be obtained. Incidentally, the first angle θ1 is typically a substantially right angle, but is not limited to being a substantially right angle, and can be any angle required for the final molded product.

[0029] However, as in the conventional technology described with reference to FIG. 2(a) at the beginning of this specification, when the intermediate material 130 is removed from the mold after the completion of the first step (step S10), the side wall portion 132 may open due to springback, as shown by the white arrow in FIG. 4(c). This is because, as shown in FIG. 5(c), tensile stress and compressive stress act on the outside and inside of the bent portion, which is the boundary between the top plate portion 131 and the side wall portion 132, respectively, when the material 100 is bent, and as a result, stress in the contraction direction (black arrow) and stress in the extension direction (white arrow) remain on the outside and inside of the bent portion of the intermediate material 130. As a result, as shown in FIG. 4(c), the angle (flange angle θf) between the top plate portion 131 and the side wall portion 132 becomes a second angle θ2 larger than the desired first angle θ1.

[0030] The state in which the side wall portion of the intermediate material opens due to springback as described above and the flange angle, which is the angle between the top plate portion and the side wall portion of the intermediate material, becomes larger than the first angle, may be referred to hereinafter as the "first state."

[0031] Therefore, in the first method, the second step is executed in the next step S20 as illustrated in Fig. 3. The second step is a step of clamping the top plate portion of the intermediate material between a first holding member arranged on the outside of the top plate portion of the intermediate material and a second holding member arranged on the inside of the top plate portion of the intermediate material. Specifically, as illustrated in Fig. 4(d), the top plate portion 131 of the intermediate material 130 is clamped between a first holding member 51 (e.g., a die) arranged on the outside of the top plate portion 131 of the intermediate material 130 and a second holding member 52 (e.g., a pad) arranged on the inside of the top plate portion 131 of the intermediate material 130.

[0032] Next, in step S30, the third step is executed. In the third step, the side wall portion of the intermediate material in the first state described above is put into the second state, and the first end portion, which is the end portion on the tip side of the side wall portion of the intermediate material, is pressed toward the base end side while maintaining the second state. The second state is a state in which the side wall portion of the intermediate material is pushed back until the flange angle coincides with the first angle. Specifically, as shown by the black arrow in FIG. 4(d), the side wall portion 132 of the intermediate material 130 is pushed back (for example, by a pad or the like, not shown) until the flange angle θf coincides with the first angle θ1 to set it to the second state. While maintaining this second state, the first end portion E1, which is the end portion on the tip side of the side wall portion 132 of the intermediate material 130, is pressed toward the base end side (bending portion side) as shown by the arrow hatched with diagonal lines in FIG. 4(d).

[0033] In the third step, the specific means for pushing back the side wall portion 132 of the intermediate material 130 in the first state with the side wall portion 132 opened by spring back to the second state is not particularly limited. In addition, the specific means for pressing the tip end portion (first end portion E1) of the side wall portion 132 of the intermediate material 130 toward the base end portion while maintaining the second state is also not particularly limited.

[0034] 6(a) is a schematic diagram illustrating a state in which the second step of clamping the top plate portion of the intermediate material 130 between a first holding member 51 (die) disposed on the outside of the top plate portion of the intermediate material 130 and a second holding member 52 (pad) disposed on the inside of the top plate portion of the intermediate material 130 is completed. In this state, the side wall portion of the top plate portion of the intermediate material 130 is not constrained, so the intermediate material 130 is in a first state in which the side wall portion opens due to springback and the flange angle θf becomes the second angle θ2.

[0035] Next, the third step is started, and as shown in FIG. 6B, the first pressing member 61 (e.g., a pad) pushes back the side wall of the intermediate material 130 until the flange angle θf coincides with the first angle θ1 (see the black arrow) to bring the intermediate material 130 into the second state. While maintaining this second state, as shown in FIG. 6C, the second pressing member 62 (e.g., a punch) presses the tip end (first end E1) of the side wall of the intermediate material 130 toward the base end (see the arrow hatched with diagonal lines). The first pressing member 61 and the second pressing member 62 may be driven mechanically by a cam mechanism or the like, or may be driven by an actuator or the like.

[0036] As described above, the side wall portion of the intermediate material, which was in the first state, can be put into the second state, and a third step can be executed in which the first end portion, which is the end portion on the tip side of the side wall portion of the intermediate material, is pressed toward the base end while maintaining the second state; however, the above is merely one example of a means for executing the third step.

[0037] By carrying out the third step (step S30) as described above, the stress history received by the material 100 in the first step (step S10) is overwritten, and the residual stress that causes the above-mentioned springback is cancelled. As a result, the possibility that the side wall portion 132 will open due to springback when the intermediate material 130 is removed from the mold after the completion of the third step is eliminated or reduced. That is, the product 200 including the top plate portion 210 and the side wall portion 220 erected at a predetermined angle θ1 (not shown in FIG. 1) from the end of the top plate portion 210 as illustrated in FIG. 1 can be integrally formed from the plate-shaped material 100 by pressing at room temperature.

[0038] As described above, in the third step, the first end E1, which is the end on the tip side of the side wall portion 132 of the intermediate material 130, is pressed toward the base end side (bent portion side). Since the stress in the elongation direction remains in the side wall portion 132 as a result of the stress history, when the intermediate material 130 is removed from the mold after the third step is completed, the side wall portion 132 is slightly elongated due to springback caused by the residual stress (for example, see the hatched portion in (e) of FIG. 4). From the viewpoint of achieving high dimensional accuracy in the product 200, it is considered to perform the "edge cutting process" described at the beginning of this specification as an additional process. However, as described above, such additional process may cause problems such as a deterioration in product yield and / or a decrease in durability of the lower die in the edge cutting process. Therefore, it is preferable to set the pressing force and pressing amount of the first end E1 in the third step depending on, for example, the material constituting the blank 100, the plate thickness of the blank 100, and the length of the side wall 220 in the product 200, so that the length of the side wall 132 after extension due to springback satisfies the dimensional accuracy required for the side wall 220 in the product 200.

[0039] <effect> In the first method, as described above, in the third step, the side wall of the intermediate material is pushed back until the flange angle, which is the angle between the top plate and the side wall, becomes larger than the desired first angle due to springback, and the tip end of the side wall is pressed toward the base end while maintaining the side wall in the pushed-back state until the flange angle becomes the first angle. This eliminates or reduces the residual stress that causes springback in the intermediate material, and makes it possible to form a product whose flange angle matches the desired first angle.

[0040] In other words, according to the first method, in a process in which a product having a top plate portion and a side wall portion (flange portion) erected at a predetermined angle (for example, approximately a right angle) from the end of the top plate portion is integrally formed from a plate-shaped material made of a common material by press processing at room temperature, springback can be eliminated or reduced without performing the above-mentioned overhanging forming process as an additional process.

[0041] Second Embodiment Hereinafter, a method for forming a sidewall portion according to a second embodiment of the present invention (hereinafter, may be referred to as a "second method") will be described with reference to the drawings.

[0042] As described above, in the third step, the side wall portion of the intermediate material is opened by spring back and in the first state, and the specific means for pushing back the side wall portion of the intermediate material in the second state and pressing the tip end (first end) of the side wall portion of the intermediate material toward the base end while keeping the side wall portion in the second state is not particularly limited. The means illustrated in Fig. 6 is one example of the means for performing the third step.

[0043] However, the means illustrated in FIG. 6 requires a first pressing member 61 for pushing back the side wall portion of the intermediate material 130 until the flange angle θf matches the first angle θ1 (see the solid black arrow) to bring the side wall portion into the second state, and a drive device (not shown) for driving the first pressing member 61, as well as a second pressing member 62 for pressing the tip end portion (first end portion E1) of the side wall portion of the intermediate material 130 toward the base end side (see the arrow hatched with diagonal lines) while maintaining the second state.

[0044] From the standpoint of reducing as much as possible the labor, components, and costs required to carry out the side wall forming method of the present invention (the method of the present invention), it is preferable to reduce the number of components required to perform the third step and to simplify the driving mechanism.

[0045] <composition> Therefore, the second method is the above-mentioned first method, which is a method for forming a side wall portion, characterized in that the third step is performed by advancing a punch having a predetermined shape in a first direction, which is a predetermined direction, relative to the intermediate material. Hereinafter, the third step performed in the second method will be described in detail with reference to FIG. 7.

[0046] Fig. 7 is a schematic diagram illustrating the third step performed by advancing a punch having a predetermined shape in a first direction, which is a predetermined direction, relative to the intermediate material in the second method. The first direction is a direction parallel to the direction from the tip end to the base end of the side wall of the intermediate material in the second state described above. In the example shown in Fig. 7, the first direction is indicated by an upward arrow D1 hatched with diagonal lines (hereinafter, may be referred to as the "first direction D1").

[0047] As illustrated in (a) of Figure 7, the punch 70 used in the second method has a side surface facing the side wall portion 132 of the intermediate material 130 in the second state, which is provided with a first surface 71, a second surface 72 and a third surface 73, as listed below.

[0048] The first surface 71 is formed on an end portion of the punch 70 on the tip side (the downstream side in the first direction D1, i.e., the upper side in the drawing) and is an inclined surface inclined at a predetermined angle θs with respect to the first direction D1 (see FIG. 7(b)). As illustrated in FIG. 7, the first surface 71 is inclined so that the distance from the intermediate material 130 (side wall portion 132 thereof) in the direction perpendicular to the first direction D1 becomes smaller as the first surface 71 advances from the tip side to the base end side (the upstream side in the first direction D1, i.e., the lower side in the drawing) of the punch 70.

[0049] The second surface 72 is a surface adjacent to the base end side of the first surface 71 and has a shape corresponding to the outer surface of the side wall portion 132 of the intermediate material 130 in the second state. In the example shown in Fig. 7, the outer surface of the side wall portion 132 of the intermediate material 130 in the second state is a plane extending perpendicular to the top plate portion 131. Therefore, the second surface 72 of the punch 70, which has a shape corresponding to the outer surface of the side wall portion 132 of the intermediate material 130 in the second state, is also a plane extending perpendicular to the top plate portion 131 and faces the outer surface of the side wall portion 132 of the intermediate material 130 in the second state.

[0050] The third surface 73 is a surface adjacent to the base end side of the second surface 72 and has a shape capable of contacting the first end E1 of the intermediate material 130 in the second state. In the example shown in Fig. 7, the third surface 73 is formed as a flat surface extending perpendicularly from the second surface 72, and forms a step having a height corresponding to the thickness of the first end E1 of the intermediate material 130.

[0051] In the third step included in the second method, the punch 70 having the above-mentioned configuration is advanced in the first direction D1 relative to the intermediate material 130, and the processes listed below are sequentially executed. In the example shown in FIG. 7, the punch 70 is advanced in the first direction D1 relative to the intermediate material 130 fixed at a predetermined position by clamping the top plate portion 131 between the first holding member 51 (die) and the second holding member 52 (pad). However, it is sufficient that the punch 70 advances in the first direction D1 relative to the intermediate material 130. For example, contrary to the example shown in FIG. 7, the intermediate material 130 with the top plate portion 131 clamped between the first holding member 51 and the second holding member 52 may be advanced in the opposite direction to the first direction D1 relative to the punch 70 fixed at a predetermined position.

[0052] First, as illustrated in FIG. 7(a), the first end E1 is brought into contact with the first surface 71 of the punch 70. Next, although not illustrated, the first end E1 is caused to slide on the first surface 71, so that the side wall portion 132 of the intermediate material 130 starts to be accommodated from the first end E1 in the space between the second surface 72 of the punch 70 and the second holding member 52 (e.g., a pad). At this time, the flange angle θf coincides with the desired first angle θ1, and the second state is achieved. Furthermore, as illustrated in FIG. 7(b), the second surface 72 is caused to slide on the outer surface of the side wall portion 132 of the intermediate material 130, so that the first end E1 is brought into contact with the third surface 73 while maintaining the second state. In addition, as illustrated by the black arrow in FIG. 7(b), the first end is pressed toward the base end by the E1 third surface 73.

[0053] As a result of executing the third step by advancing the punch 70 in the first direction D1 as described above, the stress history that the material 100 was subjected to in the first step (step S10) is overwritten, and as illustrated in (c) of Figure 7, the stress in the contraction direction on the outside of the bent portion of the intermediate material 130 (solid arrow) and the stress in the extension direction on the inside (open arrow) are each eliminated or reduced.

[0054] <effect> As described above, in the second method, the third step is performed by advancing a punch having a predetermined shape in the first direction, which is a predetermined direction, relative to the intermediate material. That is, in the second method, the third step can be performed with a simpler configuration without the need to drive many components in a complex manner, for example, as illustrated in Fig. 6. Therefore, according to the second method, it is possible to eliminate or reduce springback of the intermediate material in a method of forming a product having an integrally formed top plate portion and side wall portion from a plate-shaped material made of a general material by press working at room temperature, while suppressing the increase in required labor, components, and costs.

[0055] Third Embodiment Hereinafter, a method for forming a sidewall portion according to a third embodiment of the present invention (hereinafter, may be referred to as a "third method") will be described with reference to the drawings.

[0056] In the method for forming a side wall portion according to the present invention (method of the present invention) including the first and second methods, as described above, in the third step, when the side wall portion of the intermediate material opens due to springback and the flange angle, which is the angle between the top plate portion and the side wall portion, becomes larger than the desired first angle, the side wall portion of the intermediate material is pushed back until the flange angle becomes the first angle, while maintaining the state, and the tip end of the side wall portion is pressed toward the base end. This eliminates or reduces the residual stress that causes springback in the intermediate material, and makes it possible to form a product whose flange angle matches the desired first angle.

[0057] In other words, according to the method of the present invention, in a process in which a product having a top plate portion and a side wall portion (flange portion) erected at a predetermined angle (for example, approximately a right angle) from the end of the top plate portion is integrally formed from a plate-shaped material made of a common material by press processing at room temperature, springback can be eliminated or reduced without performing the above-mentioned overhanging forming process as an additional process.

[0058] From the viewpoint of further improving the dimensional accuracy of the shape of the side wall portion of the product formed by the method of the present invention, when pressing the tip end (first end) of the side wall portion of the intermediate material maintained in the second state in the third step toward the base end, it is preferable to press the first end inside the closed space.

[0059] <composition> Therefore, the third method is the above-mentioned second method, which is a method for forming a side wall portion, characterized in that in the third step, a portion of the side wall portion of the intermediate material including at least a first end portion is pressed toward the base end while the portion is contained inside the closed space.

[0060] Furthermore, the specific configuration of the above-mentioned closed space is not particularly limited, so long as it is possible to eliminate or reduce residual stress that causes springback of the intermediate material by pressing the first end toward the base end, and to improve the dimensional accuracy of the shape of the side wall portion of the product formed by the third method.

[0061] Fig. 8 is a schematic diagram illustrating a state in which at least a portion including the first end of the side wall of the intermediate material is housed inside a closed space in a third step included in the third method, and the first end is pressed toward the base end. Fig. 8 is the same as Fig. 6 except that when the side wall of the intermediate material 130 is pushed back by the first pressing member 61 until the flange angle θf coincides with the first angle θ1 (see the black arrow) to set the second state, the first holding member 51 and the first pressing member 61 arranged on the outside of the top plate of the intermediate material 130 come into contact with each other, and a closed space is defined by the second holding member 52, the first holding member 51, and the first pressing member 61 arranged on the inside of the top plate of the intermediate material 130.

[0062] 8, as illustrated in (c), in a state in which the side wall portion of the intermediate material 130 is housed inside the closed space defined by the second holding member 52, the first holding member 51, and the first pressing member 61, the first end E1 of the side wall portion is pressed toward the base end side by the second pressing member 62 (see the arrow hatched with diagonal lines). This makes it possible to further improve the dimensional accuracy of the shape of the side wall portion of the product formed by the third method.

[0063] 7 referred to in the description of the second method described above, in the third step, the first end is pressed toward the base end with at least a portion of the side wall of the intermediate material including the first end contained within the closed space. More specifically, in the example shown in FIG. 7, in the third step, a closed space is defined by the first holding member 51 and the second holding member 52 and the second surface 72 and the third surface 73 of the punch 70, and the first end E1 is pressed toward the base end with the side wall of the intermediate material 130 contained within the closed space.

[0064] <effect> As described above, in the third step included in the third method, the first end is pressed toward the base end while at least a portion including the first end of the side wall of the intermediate material is housed inside the closed space. Therefore, according to the third method, it is possible to eliminate or reduce springback of the intermediate material in a method of forming a product having an integrally formed top plate and side wall from a plate-shaped material made of a general material by press working at room temperature while further improving the dimensional accuracy of the shape of the side wall of the formed product.

[0065] For the purpose of explaining the present invention, several embodiments having specific configurations have been described with reference to the attached drawings. However, the scope of the present invention should not be construed as being limited to these exemplary embodiments, and it goes without saying that appropriate modifications can be made within the scope of the claims and the matters described in the specification.

[0066] For example, the method for forming a side wall portion according to the present invention (the method of the present invention) is not limited to application to the molding of a product having a flat side wall portion (flange) rising from one linear edge of the top plate portion as described above. For example, the method of the present invention can also be applied to the molding of a product having a curved side wall portion (flange) rising from a curved edge of the top plate portion. The method of the present invention can also be applied to the molding of a product having a side wall portion (flange) rising from the entire circumference of the edge of the top plate portion. Furthermore, the method of the present invention can also be applied to the molding of a bowl-shaped product having a side wall portion (flange) rising from the entire circumference of the edge of a disk-shaped top plate portion. [Explanation of symbols]

[0067] 11…First lower die 12…Second lower die 13…Third lower die 21…First pad 22…Second pad 31…First bending blade 32…Second bending blade 41...First punch 51...first holding member 52...Second holding member 61...first pressing member 62...Second pressing member 70...Punch 71...Side 1 72…Second side 73...Side 3 100...Material 110…First intermediate material 120…Second intermediate material 130...Intermediate material 131…Tabletop 132…Side wall 200…Products 210…Tabletop 220…Side wall 300…Scrap

Claims

1. A method for forming a side wall portion in a method for integrally forming a product having a top plate portion and a side wall portion erected at a first angle, which is a predetermined angle, from an end of the top plate portion from a plate-shaped material by press working at room temperature, comprising: a first step of obtaining an intermediate material having an integrally formed top plate portion and side wall portion by bending an end portion of the material at the first angle by bending and / or drawing; a second step of clamping the top plate portion of the intermediate material between a first holding member disposed on an outer side of the top plate portion of the intermediate material and a second holding member disposed on an inner side of the top plate portion of the intermediate material; and a third step of changing the side wall portion of the intermediate material from a first state in which the side wall portion of the intermediate material opens due to spring back and a flange angle, which is an angle between the top plate portion and the side wall portion of the intermediate material, is larger than the first angle, to a second state in which the side wall portion is pushed back until the flange angle coincides with the first angle, and pressing a first end portion, which is an end portion on the tip side of the side wall portion of the intermediate material, toward a base end side while maintaining the second state; Including, The third step is carried out by advancing a punch having a predetermined shape in a first direction, which is a predetermined direction, relative to the intermediate material; the first direction is a direction parallel to a direction from the tip side to the base end side of the side wall portion of the intermediate material in the second state, a first surface is formed on a tip end of the punch and is an inclined surface inclined at a predetermined angle with respect to the first direction, a second surface is adjacent to a base end of the first surface and has a shape corresponding to an outer surface of the side wall of the intermediate material in the second state, and a third surface is adjacent to a base end of the second surface and has a shape capable of coming into contact with the first end of the intermediate material in the second state, In the third step, as the punch advances in the first direction, abutting the first end on the first surface; Sliding the first end on the first surface causes the flange angle to match the first angle to achieve the second state; the second surface is slid along the outer surface of the side wall portion of the intermediate material to bring the first end into contact with the third surface while maintaining the second state; The first end portion is pressed toward the base end portion by the third surface.

13. A method for forming a side wall portion, comprising:

2. 2. A method for forming a sidewall portion according to claim 1, comprising the steps of: In the third step, a third surface of the punch is disposed on the side wall portion of the intermediate material and the first end portion of the intermediate material is pressed toward the base end side in a state where at least the first end portion of the side wall portion of the intermediate material is accommodated in a closed space defined by the first holding member, the second holding member, and the second surface and the third surface of the punch; 13. A method for forming a side wall portion, comprising:

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