Manufacturing method and stamping system of bottom container

Abstract

The present invention provides a method and a stamping system for manufacturing a container with a bottom, which suppresses deformation on the bottom side of the workpiece when a square cylindrical container with a bottom is manufactured by performing multiple stamping and drawing processes using multiple dies with long hole-shaped forming holes to form a workpiece from a flat plate state into a square cylindrical state with a bottom. The first stamping and drawing process (S1) is performed using a first die (71A) having a first long hole-shaped forming hole (73A), and is configured as at least any stamping and drawing process other than the final one. The second stamping and drawing process (S2) is performed using a second die (71B) having a second long hole-shaped forming hole (73B), and is configured as the next stamping and drawing process after the first stamping and drawing process (S1). The first forming hole (73A) is formed so that the dimension in the width direction (Y) perpendicular to the length direction (X) is larger than the dimension in the width direction (Y) perpendicular to the length direction (X) of the second forming hole (73B), and is formed so as to narrow from the two end sides in the length direction (X) to the center side toward the inner side in the width direction (Y).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a container with a bottom and a punching system, wherein a workpiece is formed from a flat plate state into a square tube state with a bottom by performing multiple punching and drawing processes, thereby manufacturing a square tube-shaped container with a bottom. Background Art

[0002] When performing stamping, a workpiece is processed using a die, and the die includes: a die provided with a forming hole, and a punch for pressing the workpiece into the forming hole of the die. Furthermore, when forming a square cylindrical bottomed container having a shape in the longitudinal direction and a bottom, a plurality of dies having long hole-shaped forming holes are used to perform multiple stamping and drawing processes to perform stamping forming of the square cylindrical bottomed container from a flat plate. For example, non-patent document 1 discloses a stamping method, which uses a plurality of dies having long hole-shaped forming holes to perform multiple stamping and drawing processes, thereby forming a square cylindrical bottomed container having a substantially rectangular cross-section from a flat plate.

[0003] As disclosed in non-patent document 1, multiple stamping and drawing processes are performed using multiple dies with elongated forming holes to form a square cylindrical bottom container from a flat plate for manufacturing. In addition, sometimes, the shape of the bottom container formed by the multiple stamping and drawing processes determines the final shape of the product, but sometimes, after the multiple stamping and drawing processes are completed, the formed square cylindrical bottom container is further subjected to a thinning and drawing process. In the thinning and drawing process performed after the multiple stamping and drawing processes are completed, the formed square cylindrical bottom container is thinned and drawn using a die for thinning and drawing. The thinning and drawing process thins and draws the plate thickness of the wall portion of the bottom container to reduce the thickness and determine the final shape of the product.

[0004] As disclosed in non-patent document 1, when forming a bottomed container having a substantially rectangular cross-section and a square tube shape, a die having a forming hole is used in a stamping and drawing process other than the final one in multiple stamping and drawing processes, and the forming hole is a shape that has no straight line portion and expands outward in an elliptical shape. That is, in a stamping and drawing process of an intermediate process other than the final stamping and drawing process that defines the final shape of the product or defines a shape corresponding to the final shape of the product, the shape of the long hole-shaped forming hole on the die is smoothly connected in an arc shape throughout the entire circumference to form a shape that expands in an elliptical shape.

[0005] When a die with a long hole-shaped forming hole is used for stamping and drawing, a compressive force is generated in the part of the workpiece being processed in the direction in which the forming hole extends in the long hole shape, that is, in the two end sides of the length direction. On the other hand, when the part of the long hole-shaped forming hole extending in the length direction is formed into a straight line, the part of the workpiece being processed on the central side of the length direction of the forming hole will be in a state where no circumferential force is generated but a bending process is performed. In this case, the workpiece is in a state where a compressive force is applied from the part being processed on the two end sides in the length direction to the part being processed on the central side in the length direction. That is, a compressive force is generated in the part being processed on the two end sides in the length direction, and due to this influence, a compressive force is also generated on the central side in the length direction in the state of bending. Therefore, the part being processed on the central side in the length direction is prone to buckling and wrinkles. Therefore, as disclosed in non-patent document 1, when a die having a long hole-shaped forming hole is used for stamping and drawing in a stamping and drawing process other than the final step, a die having a forming hole that expands outward in an elliptical shape throughout the entire circumference is used. Since a die having a forming hole that expands in an elliptical shape is used, in the workpiece subjected to stamping and drawing, a compressive force is generated not only in the parts processed on both end sides in the longitudinal direction, but also in the parts processed on the central side in the longitudinal direction. Therefore, a compressive force is generated throughout the entire circumference of the workpiece, so that the part processed on the central side in the longitudinal direction is not easy to buckle, and the generation of wrinkles can be suppressed.

[0006] Prior art literature

[0007] Non-patent literature

[0008] Non-patent document 1: Hiromi Yoshida, “Stamping Processing Encyclopedia,” Nikkan Kogyo Shimbun, September 2015, pp. 94-95. Summary of the invention

[0009] 1. Technical issues to be resolved

[0010] In the stamping and drawing process using a die with a long hole-shaped forming hole, a compression force is generated throughout the entire circumference of the workpiece by using a die with a forming hole that expands in an elliptical shape, so that the generation of wrinkles caused by the bending of the central side in the length direction can be suppressed. However, the amount of drawing on the two end sides in the length direction is large, and plastic flow of material from the two end sides in the length direction to the central side occurs, so circumferential compression force is also generated for the portion processed on the central side in the length direction. In this state, the volume of the material on the central side in the length direction is excessive. Therefore, the material on the central side in the length direction with excess volume plastically flows to the bottom side of the workpiece that is not constrained by the punch and die of the die. As a result, there is a problem that deformation is easily generated on the bottom side of the central side portion in the length direction of the workpiece after the stamping and drawing process. In addition, regarding the workpiece formed after multiple stamping and drawing processes, that is, the bottom container, if deformation occurs on the bottom side of the central side portion in the length direction, when the thinning and drawing process is performed after the multiple stamping and drawing processes, the bottom container will have overall deformation and dimensional anomaly. More specifically, if deformation occurs on the bottom side of the central side portion in the length direction after multiple stamping and drawing processes, when the thinning and drawing process is performed afterwards, not only the bottom side portion of the bottom container but also the wall portion of the bottom container will be deformed, and in addition, the corner portion of the bottom of the bottom container will also have dimensional anomaly. Therefore, when the thinning and drawing process is performed after the stamping forming of the multiple stamping and drawing processes is implemented, there is the following problem, that is, due to the deformation on the bottom side of the workpiece, the wall portion of the bottom container after the thinning and drawing process will also be deformed, or the corner portion of the bottom of the bottom container will also have dimensional anomaly.

[0011] The present invention is made in view of the above situation, and its purpose is to provide a manufacturing method and stamping system for a container with a bottom, which can suppress deformation on the bottom side of the workpiece when a square cylindrical container with a bottom is manufactured by using multiple molds with long hole-shaped forming holes to perform multiple stamping and drawing processes to form the workpiece from a flat plate state into a square cylindrical state with a bottom.

[0012] (II) Technical solution

[0013] (1) The method for manufacturing a container with a bottom of the present invention is characterized in that the workpiece is formed from a flat plate into a square tube-shaped state with a bottom by performing a plurality of stamping and drawing steps using a plurality of dies having elongated forming holes, thereby manufacturing a square tube-shaped container with a bottom. The method for manufacturing a container with a bottom is characterized in that:

[0014] a first stamping and drawing process, which is performed using a first die including a die and a punch, and is configured as at least any one of the stamping and drawing processes excluding the final stamping and drawing process from the multiple stamping and drawing processes, wherein the die has a first forming hole in the shape of a long hole as the forming hole, and the punch presses the workpiece into the first forming hole; and

[0015] The second stamping and drawing process is performed using a second die and is configured as a next stamping and drawing process after the first stamping and drawing process in the multiple stamping and drawing processes, wherein the second die has a second forming hole in the shape of a long hole as the forming hole,

[0016] The first forming hole is formed so that, over the entire length of the first forming hole in the vertical direction that passes through the die, the dimension of the width direction that is perpendicular to the length direction that extends in the shape of the long hole is larger than the dimension of the second forming hole in the width direction that is perpendicular to the length direction that extends in the shape of the long hole.

[0017] The first forming hole is formed over the entire length in the up-down direction and is narrowed toward the inside in the width direction from both ends to the center in the length direction.

[0018] The outer peripheral shape of the punch is formed into a shape corresponding to the first forming hole, and the cross-sectional shape of the punch is formed to be curved and concave inwardly in a direction parallel to the width direction from both end sides in a direction parallel to the length direction to the center side.

[0019] According to the manufacturing method of the bottomed container described in (1) above, the first forming hole is formed so as to narrow from both ends in the length direction to the center side, and toward the inside in the width direction, within the range of the width direction dimension larger than the width direction dimension of the second forming hole. Thus, in the first stamping and drawing process, for the workpiece, the portion processed on the center side in the length direction of the first forming hole is in a state where a drawing force is generated along the circumferential direction of the first forming hole. Therefore, for the workpiece, the circumferential drawing force generated by the portion processed on the center side in the length direction of the first forming hole counteracts the compression force generated by the portion processed on the both ends in the length direction of the first forming hole. Thus, the excess volume of the material processed on the center side in the length direction of the first forming hole is suppressed, and the plastic flow to the bottom side of the workpiece is suppressed. In addition, the first forming hole is formed so as to narrow from both ends in the length direction to the center side, and toward the inside in the width direction, within the range of the width direction dimension larger than the width direction dimension of the second forming hole, over the entire length in the up-down direction. Therefore, during the entire process of the first stamping and drawing process, the forces acting on the workpiece at both end sides and the center side in the length direction of the first forming hole can be adjusted, covering the entire length in the up-down direction, thereby suppressing the excess volume of the material processed on the center side in the length direction of the first forming hole, and suppressing the plastic flow to the bottom side of the workpiece. Furthermore, in the second stamping and drawing process, the excess volume on the center side in the length direction is suppressed, and the plastic flow to the bottom side is suppressed, so that the workpiece in this state passes through the second forming hole whose dimension in the width direction is smaller than that of the first forming hole, and is stamped and drawn to form a square tube-like state or a state close to a square tube-like state. In this way, after the final stamping and drawing process, the workpiece is finally formed into a square tube-like state. Thus, according to the manufacturing method of the bottom container described in (1), for the workpiece, in the first stamping and drawing process, the excess volume on the central side in the longitudinal direction is suppressed, and the plastic flow to the bottom side is suppressed to perform stamping, and in the second stamping and drawing process, the workpiece is drawn in the width direction and stamped into a square tube-like state or a state close to a square tube-like state. Therefore, according to the manufacturing method of the bottom container described in (1), for the workpiece, deformation on the bottom side of the central side portion in the longitudinal direction can be suppressed. In addition, in the manufacturing method of the bottom container described in (1), the circumferential drawing force generated by the portion processed on the central side in the longitudinal direction counteracts the circumferential compression force generated by the portion processed on the two end sides in the longitudinal direction, so that the portion processed on the central side in the longitudinal direction is not easy to bend, and the generation of wrinkles can be suppressed. In addition, the "width direction" is a direction perpendicular to the "direction extending in the shape of a long hole, that is, the length direction", and is a direction perpendicular to the two directions of the "length direction" and the "up and down direction". In addition, “the direction in which the long holes are extended” and “the direction in which the long holes are extended” have the same meaning.

[0020] As described above, according to the manufacturing method of a bottomed container described in (1) above, when a square cylindrical container with a bottom is manufactured by forming the workpiece from a flat plate state into a square cylindrical state with a bottom by performing multiple stamping and drawing processes using multiple molds with long hole-shaped forming holes, deformation on the bottom side of the workpiece can be suppressed.

[0021] (2) In the method for manufacturing a bottomed container of the present invention, preferably,

[0022] The first stamping and drawing step is configured as a first stamping and drawing step among the plurality of stamping and drawing steps.

[0023] In the initial stamping and drawing process of stamping and drawing a workpiece in a flat state, the compressive force generated in the parts processed on the two end sides in the longitudinal direction of the forming hole also increases. However, according to the manufacturing method of the bottomed container described in (2) above, in the initial stamping and drawing process, a circumferential drawing force can be generated in the part processed on the central side in the longitudinal direction of the forming hole in a manner that counteracts the circumferential compressive force generated in the parts processed on the two end sides in the longitudinal direction of the forming hole. Therefore, even in the initial stamping and drawing process in which deformation of the bottom side of the workpiece is likely to occur, deformation on the bottom side of the workpiece can be efficiently suppressed.

[0024] (3) In the method for manufacturing a bottomed container of the present invention, preferably,

[0025] The first molded hole is formed to narrow while curving toward the inside in the width direction from both ends to the center in the longitudinal direction, and narrows to the narrowest point toward the inside in the width direction at the center position in the longitudinal direction.

[0026] According to the manufacturing method of the bottomed container described in (3) above, the circumferential tensile force can be generated in the portion processed on the central side in the longitudinal direction in a manner that more evenly opposes the circumferential compressive force generated in the portions processed on the two end sides in the longitudinal direction. Therefore, the deformation generated on the bottom side of the workpiece can be more effectively suppressed.

[0027] (4) With respect to the punching system of the present invention, a plurality of punching and drawing processes are performed multiple times using a plurality of dies having long hole-shaped forming holes to form a workpiece from a flat plate state into a square tube-shaped state having a bottom, thereby forming a square tube-shaped bottomed container.

[0028] The punching system is characterized by:

[0029] A first stamping part, which has a first die including a die and a punch, and uses the first die to perform a first stamping and drawing process, wherein the die has a first forming hole in the shape of an elongated hole as the forming hole, and the punch presses the workpiece into the first forming hole, and the first stamping and drawing process is constituted by at least any one of the stamping and drawing processes excluding the final stamping and drawing process from the multiple stamping and drawing processes; and

[0030] A second stamping part, which has a second die, and uses the second die to perform a second stamping and drawing process, wherein the second die has a second forming hole in the shape of a long hole as the forming hole, and the second stamping and drawing process is constituted as the next stamping and drawing process after the first stamping and drawing process in the multiple stamping and drawing processes,

[0031] The first forming hole is formed so that, over the entire length of the first forming hole in the vertical direction that passes through the die, the dimension of the width direction that is perpendicular to the length direction that extends in the shape of the long hole is larger than the dimension of the second forming hole in the width direction that is perpendicular to the length direction that extends in the shape of the long hole.

[0032] The first forming hole is formed over the entire length in the up-down direction and is narrowed toward the inside in the width direction from both ends to the center in the length direction.

[0033] The outer peripheral shape of the punch is formed into a shape corresponding to the first forming hole, and the cross-sectional shape of the punch is formed to be curved and concave inwardly in a direction parallel to the width direction from both end sides in a direction parallel to the length direction to the center side.

[0034] According to the stamping system described in (4) above, the first forming hole provided in the first die of the first stamping part is formed to be narrowed from the two end sides in the length direction to the center side, and toward the inner side in the width direction, within the range of the width direction size larger than the width direction size of the second forming hole provided in the second die of the second stamping part. Thus, when the first stamping and drawing process is performed by the first stamping part, the portion of the workpiece processed on the center side in the length direction of the first forming hole is in a state where a drawing force is generated along the circumferential direction of the first forming hole. Therefore, for the workpiece, the circumferential drawing force generated by the portion processed on the center side in the length direction of the first forming hole counteracts the compression force generated by the portion processed on the two end sides in the length direction of the first forming hole. Thus, the excess volume of the material processed on the center side in the length direction of the first forming hole is suppressed, and the plastic flow to the bottom side of the workpiece is suppressed. In addition, the first forming hole is formed to be narrowed from the two end sides in the length direction to the center side, and toward the inner side in the width direction, within the range of the width direction size larger than the width direction size of the second forming hole, over the entire length in the up-down direction. Therefore, during the entire process of the first stamping and drawing process, the forces acting on the workpiece at both end sides and the center side in the length direction of the first forming hole can be adjusted, covering the entire length in the up-down direction, thereby suppressing the excess volume of the material processed on the center side in the length direction of the first forming hole, and suppressing the plastic flow to the bottom side of the workpiece. Furthermore, when the second stamping and drawing process is performed by the second stamping portion, the excess volume on the center side in the length direction is suppressed, and the plastic flow to the bottom side is suppressed, so that the workpiece in this state passes through the second forming hole whose dimension in the width direction is smaller than that of the first forming hole, and is stamped and drawn to form a square tube-like state or a state close to a square tube-like state. In this way, after the final stamping and drawing process, the workpiece is finally formed into a square tube-like state. Thus, according to the stamping system described in (4), for the workpiece, in the first stamping and drawing process performed by the first stamping part, the excess volume on the central side in the longitudinal direction is suppressed, and the plastic flow to the bottom side is suppressed to perform stamping, and in the second stamping and drawing process performed by the second stamping part, the workpiece is drawn in the width direction and stamped into a square tube-like state or a state close to a square tube-like state. Therefore, according to the stamping system described in (4), for the workpiece, deformation on the bottom side of the central side portion in the longitudinal direction can be suppressed. In addition, in the stamping system described in (4), the circumferential drawing force generated by the portion processed on the central side in the longitudinal direction counteracts the circumferential compression force generated by the portion processed on the two end sides in the longitudinal direction, so that the portion processed on the central side in the longitudinal direction is not easy to bend, and the generation of wrinkles can be suppressed. In addition, the "width direction" is a direction perpendicular to the "direction extending in the shape of a long hole, that is, the length direction", and is a direction perpendicular to the two directions of the "length direction" and the "up and down direction".In addition, “the direction in which the long holes are extended” and “the direction in which the long holes are extended” have the same meaning.

[0035] As described above, according to the stamping system described in (4) above, when a square cylindrical bottomed container is formed by forming the workpiece from a flat plate state into a square cylindrical state with a bottom by performing multiple stamping and drawing processes using multiple dies having long hole-shaped forming holes, deformation on the bottom side of the workpiece can be suppressed.

[0036] (5) In the punching system of the present invention, preferably,

[0037] The first stamping section performs the first stamping and drawing process using the first die, and the first stamping and drawing process is configured as a first stamping and drawing process in the plurality of stamping and drawing processes.

[0038] In the initial stamping and drawing process of stamping and drawing a workpiece in a flat state, the compressive force generated by the parts processed on the two end sides in the longitudinal direction of the forming hole also increases. However, according to the stamping system described in (5) above, when the initial stamping and drawing process is performed by the first stamping part, a circumferential drawing force can be generated on the part processed on the central side in the longitudinal direction of the forming hole in a manner that counteracts the circumferential compressive force generated by the parts processed on the two end sides in the longitudinal direction of the forming hole. Therefore, even in the initial stamping and drawing process in which deformation of the bottom side of the workpiece is likely to occur, deformation on the bottom side of the workpiece can be efficiently suppressed.

[0039] (6) In the punching system of the present invention, preferably,

[0040] The first molded hole is formed to narrow while curving toward the inside in the width direction from both ends to the center in the longitudinal direction, and narrows to the narrowest point toward the inside in the width direction at the center position in the longitudinal direction.

[0041] According to the punching system described in (6) above, the circumferential tensile force can be generated in the portion processed on the central side in the longitudinal direction in a more balanced manner to counteract the circumferential compressive force generated in the portions processed on the two end sides in the longitudinal direction. Therefore, deformation on the bottom side of the workpiece can be more efficiently suppressed.

[0042] (III) Beneficial effects

[0043] According to the present invention, a method for manufacturing a container with a bottom and a stamping system can be provided. When a square cylindrical container with a bottom is manufactured by forming a workpiece from a flat plate state into a square cylindrical state with a bottom through multiple stamping and drawing processes using multiple dies with long hole-shaped forming holes, deformation on the bottom side of the workpiece can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is an example of a press system according to the present embodiment.

[0045] Figure 2 It is a side cross-sectional view of a multi-station punching device in a punching system, and is a view showing an enlarged portion of the multi-station punching device.

[0046] Figure 3 It is a flowchart showing an example of the manufacturing method of the bottomed container of this embodiment, and is a flowchart showing an example of a plurality of punching and drawing processing steps performed by a punching system.

[0047] Figure 4 is a diagram showing an example of a first die used in a first stamping and drawing process in a method for manufacturing a bottomed container, and is a diagram showing an example of a first die of a first stamping portion of a stamping system, wherein: Figure 4 (A) is a top cross-sectional view of the punch in the first die. Figure 4 (B) is a top view of the punch die in the first mold. Figure 4 (C) is Figure 4 (B) Cross-sectional view along line A-A.

[0048] Figure 5 is a diagram showing an example of a second die used in a second stamping and drawing process in a method for manufacturing a bottomed container, and is a diagram showing an example of a second die of a second stamping portion of a stamping system, wherein: Figure 5 (A) is a top cross-sectional view of the punch in the second die, Figure 5 (B) is a top view of the punch die in the second mold. Figure 5 (C) is Figure 5 (B) is a cross-sectional view taken along line BB.

[0049] Figure 6 This is a diagram for explaining a workpiece subjected to a punching and drawing process in a method for manufacturing a bottomed container and a punching system.

[0050] Figure 7 It is a diagram that compares and schematically shows the forming holes of the die used in the first stamping and drawing process and the second stamping and drawing process in the manufacturing method of a bottomed container, and it is a diagram that compares and schematically shows the forming holes of the die used in the first stamping and drawing process and the second stamping and drawing process performed by the first stamping part and the second stamping part in the stamping system.

[0051] Figure 8It is a diagram for explaining the forces acting on the workpiece in the first stamping and drawing process of the manufacturing method of the bottomed container, and is a diagram for explaining the forces acting on the workpiece in the first stamping and drawing process performed by the first stamping part of the stamping system.

[0052] Fig. 9 It is a diagram for explaining the conventional stamping and drawing process, wherein: Fig. 9 (A) is a top view of the die. Fig. 9 (B) is a cross-sectional view showing a state where a workpiece is subjected to a drawing process. Fig. 9 (C) is to Fig. 9 This is a diagram showing an enlarged view of the portion D surrounded by a dotted line in (B).

[0053] Fig.10 It is a diagram for explaining the first stamping and drawing process in the manufacturing method of the bottomed container and the first stamping and drawing process performed by the first stamping part of the stamping system, wherein: Fig.10 (A) is a top view of the die. Fig.10 (B) is a cross-sectional view showing a state where a workpiece is subjected to a drawing process. Fig.10 (C) is to Fig.10 This is an enlarged view of part F surrounded by a dotted line in (B).

[0054] Fig.11 is a diagram for explaining the appearance characteristics of a manufactured bottomed container, wherein: Fig.11 (A) is a diagram for explaining the appearance characteristics of a container with a bottom manufactured by a conventional method for manufacturing a container with a bottom. Fig.11 (B) is a diagram for explaining the external appearance features of the container with a bottom manufactured by the method for manufacturing a container with a bottom according to the present embodiment.

[0055] Fig.12 The flowchart of the manufacturing method of the bottomed container of the modified example is shown, and the flowchart of multiple punching and drawing processing steps performed by the punching system of the modified example is shown.

[0056] Fig.13 is a diagram showing an example of a die used in a stamping and drawing process in a method for manufacturing a bottomed container according to a modified example, and is a diagram showing an example of a die of a stamping system according to a modified example, wherein: Fig.13 (A) is a top view of the punch and the die used in the first stamping and drawing process. Fig.13 (B) is a top view of the punch and the die used in the second stamping and drawing process. Fig.13 (C) is a top cross-sectional view of the punch in the die used in the third stamping and drawing process and a top view of the die.

[0057] Fig.14 This is a diagram that compares and schematically shows the forming holes of the die used in multiple stamping and drawing processes in the manufacturing method of the bottomed container of the modified example, and is a diagram that compares and schematically shows the forming holes of the die used in multiple stamping and drawing processes performed in the stamping system of the modified example. DETAILED DESCRIPTION

[0058] Hereinafter, a method for implementing the present invention will be described with reference to the accompanying drawings of the specification. In addition, the present invention can be widely applied to various purposes as a method for manufacturing a bottom container by forming a workpiece from a flat plate state into a square tube-shaped state with a bottom by performing multiple stamping and drawing processes using multiple dies with long hole-shaped forming holes to manufacture a square tube-shaped container with a bottom. In addition, the present invention can be widely applied to various purposes as a stamping system by forming a workpiece from a flat plate state into a square tube-shaped state with a bottom by performing multiple stamping and drawing processes using multiple dies with long hole-shaped forming holes to manufacture a square tube-shaped container with a bottom. In the following description, the schematic structure of the stamping system and the method for manufacturing a bottom container of the embodiment of the present invention is first described, and then the characteristic structure of the stamping system and the method for manufacturing a bottom container of the embodiment of the present invention is described.

[0059] [1. Overview of the press system]

[0060] Figure 1 This is an example of a press system 1 according to an embodiment of the present invention. Figure 2 1 is a side cross-sectional view of the multi-station punching device 50 in the punching system 1, and is a diagram showing a part of the multi-station punching device 50 in an enlarged manner. Figure 1 and Figure 2 Each direction of the up-down direction, the left-right direction, and the front-back direction is defined as shown.

[0061] Reference Figure 1 The punching system 1 includes a workpiece supply device 10 and a multi-station punching device 50. In this embodiment, the workpiece supply device 10 is arranged on the left side, and the multi-station punching device 50 is arranged on the right side. The workpiece supply device 10 supplies the workpiece W to the multi-station punching device 50.

[0062] The workpiece supply device 10 supplies the workpiece W to the multi-station punching device 50 (see the following). Figure 4 and Figure 6The workpiece supply device 10 is provided with a frame 12 composed of a pair of side walls 13A and 13B vertically erected and opposed to each other in the left-right direction. The frame 12 is formed into a structure in which a pressure head support wall 14 and a pad support wall 16 are provided between the pair of side walls 13A and 13B. In addition, a pair of rails 82A and 82B (see Figure 2 ) driven driving unit 32.

[0063] The ram support wall 14 supports the ram 20 so that it can move in the up-down direction, that is, perform a lifting action. The ram 20 can move in the up-down direction by receiving power from a servo motor not shown in the figure through the camshaft 22. In addition, the ram 20 supports a punch not shown in the figure. The left end of the camshaft 22 penetrates the left side wall 13A of a pair of side walls 13A and 13B arranged opposite to each other in the left-right direction and protrudes outward. The part that penetrates the left side wall 13A and protrudes outward is connected to the above-mentioned servo motor not shown via a pulley 24 and a timing belt not shown. When the camshaft 22 is rotated by the servo motor not shown, the ram 20 reciprocates up and down. In addition, a flywheel 26 is installed at the left end of the camshaft 22 together with the pulley 24. Various components including the pulley 24, the timing belt not shown and the flywheel 26 are covered by a side cover 28 fixed to the outer side of the side wall 13A.

[0064] The pad support wall 16 supports the die holder 30 via the pad 18. The die holder 30 has a two-layer structure of an upper layer and a lower layer. The upper surface of the lower layer of the die holder 30 is flush with the upper surface of the die holder 70 described later of the multi-station punching device 50. The upper layer of the die holder 30 is arranged above the upper surface of the lower layer with a gap. A die (not shown) is held in the upper layer of the die holder 30.

[0065] In the workpiece supply device 10, the press head 20 is moved downward, and the metal plate is punched by a punch and a die (not shown) supported by the press head 20, thereby forming a flat workpiece W (see the following). Figure 4 and Figure 6 The workpiece W formed in a flat plate state by the workpiece supply device 10 is supplied to the multi-station punching device 50 .

[0066] Reference Figure 1 The multi-station punching device 50 is arranged adjacent to the downstream side of the workpiece conveying direction of the workpiece supply device 10. The flat workpiece W formed by the workpiece supply device 10 is conveyed to the multi-station punching device 50, and the multi-station punching device 50 performs multiple punching and drawing processes on the workpiece W.

[0067] The multi-station press device 50 includes a frame 52 formed of a pair of side walls 53A and 53B vertically standing and facing each other in the left-right direction. The frame 52 is formed in a structure in which a ram support wall and a pad support wall 56 (not shown) are bridged between the pair of side walls 53A and 53B.

[0068] The ram 60 is supported by a ram support wall (not shown) so as to be movable in the up-down direction, i.e., to perform a lifting action. The ram 60 receives power from a servo motor (not shown) through a cam shaft 62 and is movable in the up-down direction. In addition, the ram 60 supports a plurality of punches 74 arranged in the left-right direction (i.e., the workpiece conveying direction). A cam shaft 62 is mounted on the upper side of the ram support wall (not shown) between a pair of side walls 53A and 53B. The ram 60 engages with a cam 61 of the cam shaft 62.

[0069] The right end of the camshaft 62 passes through the right side wall 53B of a pair of side walls 53A and 53B disposed opposite to each other in the left-right direction and protrudes outward. The portion passing through the right side wall 53B and protruding outward is connected to the above-mentioned servo motor (not shown) via a pulley 64 and a timing belt (not shown).

[0070] When the cam shaft 62 is driven to rotate by a servomotor (not shown), the pressure head 60 reciprocates up and down. In addition, a flywheel 66 is mounted on the right end of the cam shaft 62 together with the pulley 64. Various components including the pulley 64, the timing belt (not shown) and the flywheel 66 are covered by a side cover 68 fixed to the outer side surface of the side wall 53B.

[0071] The pad support wall 56 is arranged between the lower ends of the pair of side walls 53A and 53B, and a pad 58 is fixed on its upper surface. A plurality of dies 72 (see FIG. 1 ) are fixed on the upper surface of the pad 58 via a plurality of die holders 70 arranged along the workpiece conveying direction. Figure 1 and Figure 2 ). The plurality of dies 72 and the plurality of punches 74 are the same in number, and a pair of dies 72 and punches 74 arranged up and down constitute a die for performing a single stamping and drawing process. That is, the plurality of pairs of dies 72 and punches 74 arranged up and down respectively constitute a die for performing a plurality of stamping and drawing processes respectively.

[0072] Reference Figure 1 and Figure 2 The multi-station punching device 50 includes a plurality of dies, namely, a plurality of pairs of dies 72 and punches 74, arranged along the workpiece conveying direction. The plurality of pairs of dies 72 and punches 74 are arranged at a constant pitch along the left-right direction. Figure 2, each die 72 is fixed to the die holder 70. A step portion 70A is formed on the upper portion of the die holder 70. The die 72 is fixed to the step portion 70A of the die holder 70. When the die 72 is fixed to the step portion 70A, the upper surface of the die holder 70 is flush with the upper surface of the die 72. The die 72 is provided with a forming hole 73 formed in the shape of an elongated hole when viewed from above in the up and down direction. The stamping and drawing process is performed by pressing the workpiece W into the elongated hole-shaped forming hole 73 of the die 72 by the punch 74 and passing the workpiece W through the forming hole 73. The punch 74 presses the workpiece W into the elongated hole-shaped forming hole 73 of the die 72, thereby forming the workpiece W into a cylindrical shape having a slenderly extending cross-sectional shape. In addition, a demolding pin 94 is arranged below the forming hole 73 of the die 72. When the punch 74 presses the workpiece W into the forming hole 73 of the die 72 for forming, the demolding pin 94 pushes the lower surface of the workpiece W upward to limit the downward bulging of the workpiece W. In addition, when the punch 74 rises, the workpiece W can be pushed upward from the forming hole 73 of the die 72.

[0073] The workpiece W is conveyed to the downstream side in the workpiece conveying direction by the conveying device 80. The workpiece W is conveyed to the downstream side in the workpiece conveying direction by the conveying device 80 and is subjected to stamping and drawing processing by a plurality of pairs of dies 72 and punches 74 arranged in the left-right direction.

[0074] Reference Figure 1 and Figure 2 The conveying device 80 is arranged on the die holder 70 and includes a pair of rails 82A, 82B, a plurality of pairs of manipulators 84A, 84B, a plurality of pairs of cylinders 86A, 86B as drive sources for driving the plurality of pairs of manipulators 84A, 84B, respectively, and a drive unit 32 (see Figure 1 ).

[0075] The pair of rails 82A and 82B are arranged horizontally with the left-right direction as the longitudinal direction, and are arranged to extend over a plurality of pairs of dies 72 and punches 74. The pair of rails 82A and 82B are arranged parallel to each other with a certain distance in the front-back direction. A pair of manipulators 84A and 84B and a pair of air cylinders 86A and 86B are placed on the pair of rails 82A and 82B at positions corresponding to each pair of dies 72 and punches 74 in the up-down direction. Therefore, when the driving unit 32 (see Figure 1 ) When the pair of rails 82A and 82B are moved in the left-right direction, the plurality of cylinders 86A and 86B and the plurality of manipulators 84A and 84B are also moved in the left-right direction. In this way, the workpiece W clamped by the manipulators 84A and 84B can be transported to the downstream side of the workpiece transport direction. In addition, Figure 2 : shows a state where the workpiece W is clamped by the robots 84A and 84B.

[0076] like Figure 2 As shown, the manipulators 84A and 84B are respectively arranged at the front ends of the piston rods of the cylinders 86A and 86B, and are configured to be opened and closed by the actions of the cylinders 86A and 86B. With respect to the cylinders 86A and 86B, the cylinder 86A on the front side and the cylinder 86B on the rear side act symmetrically in the front-to-back direction. That is, when the cylinder 86A acts from the front direction toward the rear direction, the cylinder 86B acts from the rear direction toward the front direction. At this time, the manipulators 84A and 84B act in a direction of approaching each other, that is, from opening to closing. In addition, when the cylinder 86A acts from the rear direction toward the front direction, the cylinder 86B acts from the front direction toward the rear direction. At this time, the manipulators 84A and 84B act in a direction of separating from each other, that is, from closing to opening. By opening and closing the manipulators 84A and 84B in this way, the workpiece W can be released or clamped.

[0077] The interval between the adjacent robots 84A and 84B in the workpiece conveying direction (ie, the left-right direction) is equal to the interval between the adjacent punches 74 in the left-right direction (see Figure 1 ) and the intervals between the dies 72 are the same constant intervals. Figure 1 ) and the pressure head 60 (refer to Figure 1 ) is synchronized with the lifting action of the pair of rails 82A and 82B to keep the pair of rails 82A and 82B in a horizontal state and repeat the reciprocating action with a constant pitch in the left-right direction. In addition, multiple pairs of cylinders 86A and 86B repeat the opening and closing action of the manipulators 84A and 84B, so that the workpiece W is conveyed by the reciprocating action of the pair of rails 82A and 82B in the left-right direction. In this way, the workpiece W is conveyed by the conveying device 80 from the upstream side (i.e., the left side) in the workpiece conveying direction to the downstream side (i.e., the right side) in the workpiece conveying direction, and is stamped and drawn by multiple pairs of dies 72 and punches 74 in sequence. In this way, the workpiece W is subjected to multiple stamping and drawing processes.

[0078] When the workpiece W is subjected to a plurality of stamping and drawing processes by the stamping system 1, the number of dies 72 and punches 74 corresponding to the number of stamping and drawing processes to be performed is used. Figure 1In the illustrated stamping system 1, a method with eight pairs of dies 72 and punches 74 is illustrated. When the workpiece W is subjected to eight stamping and drawing processes, eight pairs of dies 72 and punches 74 are used. For example, when the workpiece W is subjected to two stamping and drawing processes, only two pairs of dies 72 and punches 74 are used. That is, in this case, in the stamping system 1, only any two pairs of dies 72 and punches 74 among the eight pairs of dies 72 and punches 74 are installed and used, and the other six pairs of dies 72 and punches 74 are not installed in the stamping system 1. Similarly, for example, when the workpiece W is subjected to three stamping and drawing processes, only three pairs of dies 72 and punches 74 are used. In this case, in the stamping system 1, only any three pairs of dies 72 and punches 74 among the eight pairs of dies 72 and punches 74 are installed and used, and the other five pairs of dies 72 and punches 74 are not installed in the stamping system 1. In addition, a block-shaped member without a forming hole, for example, is installed at a portion of the press system 1 where the die 72 is not installed.

[0079] The punching system 1 of the present embodiment has the above-mentioned structure as a basic device structure, and is set as a punching system that forms a square cylindrical bottomed container by performing multiple punching and drawing processes using multiple dies having long hole-shaped forming holes to form a workpiece W from a flat state to a square cylindrical state with a bottom. The multiple dies used in the multiple punching and drawing processes performed by the punching system 1 are respectively composed of a die 72 and a punch 74. A long hole-shaped forming hole 73 is provided in the die 72 of each of the multiple dies.

[0080] As the plurality of stamping and drawing steps performed by the stamping system 1 , the stamping and drawing steps may be performed twice, or three or more times. Figure 3 1 is a flowchart showing an example of a multiple punching and drawing process performed by the punching system 1. Figure 3 This is also a flowchart showing an example of a method for manufacturing a container with a bottom according to the present embodiment described later. Figure 3 The flowchart shown in FIG. 1 illustrates a method in which the stamping system 1 performs two stamping and drawing processes as multiple stamping processes. Figure 3 As shown in the flowchart of FIG. 1 , the stamping system 1 is configured to perform a first stamping and drawing process S1 and a second stamping and drawing process S2. Figure 3 In the example shown, the first stamping and drawing process constitutes the first stamping and drawing process S1, and the second stamping and drawing process constitutes the second stamping and drawing process S2. Figure 3As shown, when the stamping system 1 performs two stamping and drawing processes as multiple stamping and drawing processes, only any two pairs of dies 72 and punches 74 among the eight pairs of dies 72 and punches 74 are installed and used, and the other six pairs of dies 72 and punches 74 are not installed in the stamping system 1. That is, when the stamping system 1 performs two stamping and drawing processes, the stamping system 1 only has two pairs of dies 72 and punches 74 arranged in the workpiece conveying direction, and has two molds composed of dies 72 and punches 74.

[0081] The press system 1 includes a first press section that performs a first press-drawing step S1 and a second press section that performs a second press-drawing step S2 .

[0082] The first stamping section is configured to perform a first stamping and drawing process S1, which is configured as at least one stamping and drawing process among the multiple stamping and drawing processes excluding the final stamping and drawing process. Figure 3 As shown in the flowchart of , when the stamping system 1 performs two stamping and drawing processes as multiple stamping and drawing processes, the first stamping and drawing process S1 performed by the first stamping part is constituted as the first stamping and drawing process excluding the final, i.e., the second stamping and drawing process. And, the first stamping and drawing process S1 performed by the first stamping part is constituted as the initial stamping and drawing process in multiple stamping and drawing processes. When the stamping system 1 performs two stamping and drawing processes, the first stamping part is constituted as a die arranged on the upstream side of the workpiece conveying direction among the two dies having a die 72 and a punch 74. And, the first stamping part is constituted as a die on the upstream side of the workpiece conveying direction composed of a pair of dies 72 and a punch 74, a die holder 70 and a pad 58 supporting the die 72, a ram 60 supporting the punch 74, and a servo motor and a camshaft 62 as a mechanism for lifting and lowering the ram 60. In addition, as described later, the first punching portion includes a first die 71A including a punch die 72A (see Figure 4 ), the die 72A has a first forming hole 73A which is in the shape of a long hole and serves as the forming hole 73.

[0083] The second stamping part is configured to perform a second stamping and drawing process S2, which is configured as the next stamping and drawing process after the first stamping and drawing process S1 in the multiple stamping and drawing processes. Figure 3As illustrated in the flowchart, when the stamping system 1 performs two stamping and drawing processes as multiple stamping and drawing processes, the second stamping and drawing process S2 performed by the second stamping section is configured as the next stamping and drawing process after the first stamping and drawing process S1 as the initial stamping and drawing process, that is, the final stamping and drawing process. When the stamping system 1 performs two stamping and drawing processes, the second stamping section is configured as a die arranged on the downstream side of the workpiece conveying direction among the two dies having a die 72 and a punch 74. Furthermore, the second stamping section is configured as: a die on the downstream side of the workpiece conveying direction composed of a pair of dies 72 and a punch 74, a die holder 70 and a pad 58 supporting the die 72, a ram 60 supporting the punch 74, and a servo motor and a cam shaft 62 as a mechanism for lifting and lowering the ram 60. In addition, as described later, the second stamping section has a second die 71B (refer to Figure 5 ), the die 72B has a second forming hole 73B in the shape of a long hole as the forming hole 73.

[0084] [2. Overview of the method for manufacturing a bottomed container]

[0085] Next, the manufacturing method of the bottomed container according to the embodiment of the present invention is described. The manufacturing method of the bottomed container according to the present embodiment is a method for manufacturing a square tube-shaped container with a bottom by performing multiple stamping and drawing processes on the workpiece W from a flat state to a square tube-shaped state with a bottom using multiple dies having a long hole-shaped forming hole to manufacture a square tube-shaped container with a bottom. The manufacturing method of the bottomed container according to the present embodiment is implemented, for example, by performing multiple stamping and drawing processes on the workpiece W using a stamping system 1. Therefore, the manufacturing method of the bottomed container according to the present embodiment is configured as a method for manufacturing a bottomed container as follows, that is, by performing multiple stamping and drawing processes on the workpiece W using multiple dies configured to include a die 72 and a punch 74 and having a long hole-shaped forming hole 73 to manufacture a square tube-shaped container with a bottom by forming the workpiece W from a flat state to a square tube-shaped state.

[0086] The manufacturing method of the bottomed container of the present embodiment is configured to have multiple stamping and drawing processing steps. The manufacturing method of the bottomed container of the present embodiment can be configured to have two stamping and drawing processing steps as the multiple stamping and drawing processing steps, and can also be configured to have three or more stamping and drawing processing steps as the multiple stamping and drawing processing steps. Figure 3 Flow chart showing an example of a method for manufacturing a bottomed container according to the present embodiment. Figure 3 As shown, the method for manufacturing a bottomed container according to the present embodiment is exemplified in that the method includes a plurality of stamping and drawing steps and an ironing and drawing step performed after the plurality of stamping and drawing steps. Figure 3The method for manufacturing a bottomed container according to an example of the present embodiment shown is configured to include a first stamping and drawing step S1 and a second stamping and drawing step S2. Figure 3 The illustrated method for manufacturing a bottomed container includes two stamping and drawing steps, wherein the first stamping and drawing step is a first stamping and drawing step S1 , and the second stamping and drawing step is a second stamping and drawing step S2 .

[0087] In addition, if Figure 3 As shown, when the first stamping and drawing process S1 and the second stamping and drawing process S2 are completed, the thinning and drawing process S3 can be performed. After the multiple stamping and drawing processes are completed, the square cylindrical bottom container formed by performing the multiple stamping and drawing processes is subjected to the thinning and drawing process S3. In the thinning and drawing process S3, the square cylindrical bottom container is subjected to thinning and drawing using a mold for thinning and drawing so that the thickness of the wall of the bottom container is thinned by drawing to determine the final shape of the product. In addition, in the case where the thinning and drawing process S3 is not performed after the multiple stamping and drawing processes, the shape of the bottom container formed by the multiple stamping and drawing processes determines the final shape of the product.

[0088] The first stamping and drawing step S1 is configured as at least any one of the stamping and drawing steps excluding the final stamping and drawing step among the plurality of stamping and drawing steps. Figure 3 The manufacturing method of the bottomed container shown is a manufacturing method of the bottomed container that performs two stamping and drawing steps, so the first stamping and drawing step S1 is a first stamping and drawing step excluding the final stamping and drawing step, that is, the second stamping and drawing step. Figure 3 In the method for manufacturing a container with a bottom shown in the figure, the first stamping and drawing step S1 is configured as the first stamping and drawing step among the plurality of stamping and drawing steps.

[0089] The second stamping and drawing step S2 is configured as the next stamping and drawing step after the first stamping and drawing step S1 in the plurality of stamping and drawing steps. Figure 3 The manufacturing method of the bottomed container shown is configured as a manufacturing method of the bottomed container that performs two stamping and drawing processes, so the second stamping and drawing process S2 is configured as the next stamping and drawing process after the first stamping and drawing process S1 which is the initial stamping and drawing process, that is, the final stamping and drawing process. The manufacturing method of the bottomed container of this embodiment ends by performing the first stamping and drawing process S1 and the second stamping and drawing process S2. In addition, as Figure 3As shown, after the multiple punching and drawing steps are completed, an ironing and drawing step S3 for reducing the plate thickness of the wall portion of the bottomed container by drawing may be performed.

[0090] [3. Characteristic structures of the first and second stamping and drawing steps and the first and second stamping parts]

[0091] Next, the first and second press-drawing steps of the method for manufacturing a bottomed container according to the present embodiment and the characteristic structures of the first and second press parts of the press system 1 according to the present embodiment will be described. Figure 4 Yes means Figure 3 FIG. 1 is a diagram showing an example of a first die 71A used in the first stamping and drawing process S1 in the method for manufacturing a bottomed container shown in FIG. 1 , and is a diagram showing an example of a first die 71A of a first stamping portion of a stamping system 1 , and Figure 4 (A) is a top cross-sectional view of the punch 74A in the first die 71A, Figure 4 (B) is a top view of the punch die 72A in the first mold 71A. Figure 4 (C) is Figure 4 (B) Cross-sectional view along line A-A. Figure 5 Yes means Figure 3 FIG. 1 is a diagram showing an example of a second die 71B used in the second stamping and drawing process S2 in the method for manufacturing a bottomed container shown in FIG. 1 , and is a diagram showing an example of a second die 71B of a second stamping portion of a stamping system 1, wherein: Figure 5 (A) is a top cross-sectional view of the punch 74B in the second die 71B, Figure 5 (B) is a top view of the punch die 72B in the second die 71B. Figure 5 (C) is Figure 5 (B) is a cross-sectional view taken along line BB. Figure 6 This is a diagram for explaining a workpiece W to be subjected to a press-drawing process in the method for manufacturing a bottomed container and the press system 1 according to the present embodiment.

[0092] Reference Figure 4, the first die 71A of the first stamping part of the stamping system 1, that is, the first die 71A used in the first stamping and drawing process S1 of the manufacturing method for the bottom container of the present embodiment, is configured to include a die 72A and a punch 74A. The die 72A is set as one of the multiple dies 72 installed in the stamping system 1. The die 72A is configured as the die 72 of the first die 71A of the first stamping part of the stamping system 1, and is configured as the die 72 used in the first stamping and drawing process S1 of the manufacturing method for the bottom container of the present embodiment. The punch 74A is set as one of the multiple punches 74 installed in the stamping system 1. The punch 74A is configured as the punch 74 of the first die 71A of the first stamping part of the stamping system 1, and is configured as the punch 74 used in the first stamping and drawing process S1 of the manufacturing method for the bottom container of the present embodiment.

[0093] Reference Figure 4 (B) and Figure 4 (C), the die 72A is provided with a first formed hole 73A as a formed hole 73 in the shape of a long hole of the die 72. That is, the die 72A is provided with a first formed hole 73A as a formed hole 73 formed in the shape of a long hole when viewed from above in the up-down direction. In addition, the first formed hole 73A has a long hole-like cross-sectional shape and is provided to penetrate the die 72A in the up-down direction. The first formed hole 73A is formed so that the dimension of the direction extending in the shape of the long hole, i.e., the longitudinal direction X, is larger than the dimension of the direction perpendicular to the longitudinal direction X, i.e., the width direction Y. In addition, Figure 4 In (B), the longitudinal direction X is indicated by an arrow X at both ends, and the width direction Y is indicated by an arrow Y at both ends.

[0094] Regarding the first formed hole 73A, for example, both ends in the length direction X are formed into semicircular arc shapes. Furthermore, regarding the first formed hole 73A, the shape of the portion excluding the both ends in the length direction X in the circumferential direction is formed so as to narrow toward the inside of the width direction Y from the both end sides in the length direction X to the center side. That is, regarding the first formed hole 73A, the shape of the portion excluding the both end sides in the length direction X in the circumferential direction is formed so as to gradually reduce the size in the width direction Y from the both end sides in the length direction X to the center side. Furthermore, the first formed hole 73A is formed so as to narrow toward the inside of the width direction Y from the both end sides in the length direction X to the center side throughout the entire length of the direction in which the first formed hole 73A passes through the die 72A, that is, the up-down direction. In addition, the first formed hole 73 is formed so as to narrow toward the inside of the width direction Y while smoothly bending in an arc shape from the both end sides in the length direction X to the center side, and narrows to the narrowest toward the inside of the width direction Y at the center position CX in the length direction X. In addition, at Figure 4 In (B), the center position CX in the longitudinal direction X of the first forming hole 73A of the die 72A is indicated by a dashed line CX.

[0095] Reference Figure 4 (A), the punch 74A is formed into a shape corresponding to the first forming hole 73A of the die 72A. That is, the outer peripheral shape of the punch 74A is formed into a shape corresponding to the first forming hole 73A of the die 72A. Therefore, the punch 74A is formed so that the two ends in the direction parallel to the length direction X of the first forming hole 73A are respectively semicircular arc-shaped cross-sectional shapes. And the shape of the portion of the circumferential direction of the punch 74A excluding the two ends of the above-mentioned semicircular arc-shaped cross-sectional shape is formed so as to be smoothly curved and concave in an arc shape toward the inner side of the first forming hole 73A in the direction parallel to the width direction Y from the two end sides of the first forming hole 73A in the direction parallel to the length direction X to the central side.

[0096] The first stamping part of the stamping system 1 has a first die 71A including a die 72A, and the first stamping and drawing process S1 is performed using the first die 71A, wherein the die 72A has a first forming hole 73A in the shape of a long hole as the forming hole 73. In addition, the first stamping and drawing process S1 in the manufacturing method of the bottomed container of the present embodiment is performed using the first die 71A including the die 72A, wherein the die 72A has a first forming hole 73A in the shape of a long hole as the forming hole 73. The first stamping and drawing process S1 is performed using the die 72A and a punch 74A having a cross-sectional shape corresponding to the first forming hole 73A, wherein the first forming hole 73A is in the shape of a long hole and is a shape that is smoothly narrowed toward the inside of the width direction Y as it approaches the center side of the length direction X. In the first stamping and drawing process S1, a workpiece W1 in a flat plate state supplied from the workpiece supply device 10 of the stamping system 1 is subjected to stamping and drawing using the die 72A and the punch 74A. Figure 6 In (A), a workpiece W1 as a workpiece W in a flat plate state is shown in a perspective view. Figure 4 (B) and Figure 4 In (C), the workpiece W1 is shown by a two-dot chain line.

[0097] In the first stamping and drawing process S1 of the method for manufacturing a bottomed container of the present embodiment and the first stamping and drawing process S1 performed by the first stamping unit of the stamping system 1, the punch 74A presses the workpiece W1 into the first forming hole 73A of the die 72A, thereby forming the workpiece W1 into a workpiece W2 having a cylindrical shape with a bottom. Figure 6 In (B), a workpiece W2 as a workpiece W formed by the first stamping and drawing process S1 is shown in a perspective view. The workpiece W2 has a bottom and is formed into a shape extending in a cylindrical shape with a cross-sectional shape corresponding to the shape of the first formed hole 73A. Figure 6In (B), the upper end portion of the workpiece W2 is schematically shown in a flat state.

[0098] Reference Figure 5 , the second die 71B of the second stamping part of the stamping system 1, that is, the second die 71B used in the second stamping and drawing process S2 of the manufacturing method of the bottom container of the present embodiment, is configured to include a die 72B and a punch 74B. The die 72B is set as one of the multiple dies 72 installed in the stamping system 1. The die 72B is configured as the die 72 of the second die 71B of the second stamping part of the stamping system 1, and is configured as the die 72 used in the second stamping and drawing process S2 of the manufacturing method of the bottom container of the present embodiment. The punch 74B is set as one of the multiple punches 74 installed in the stamping system 1. The punch 74B is configured as the punch 74 of the second die 71B of the second stamping part of the stamping system 1, and is configured as the punch 74 used in the second stamping and drawing process S2 of the manufacturing method of the bottom container of the present embodiment.

[0099] Reference Figure 5 (B) and Figure 5 (C), the die 72B is provided with a second formed hole 73B as a long hole-shaped formed hole 73 of the die 72. That is, the die 72B is provided with a second formed hole 73B as a formed hole 73 formed in a long hole shape when viewed from above in the up-down direction. In addition, the second formed hole 73B has a long hole-shaped cross-sectional shape and is provided to penetrate the die 72B in the up-down direction. The second formed hole 73B is formed so that the dimension of the direction extending in the long hole shape, i.e., the longitudinal direction X, is larger than the dimension of the direction perpendicular to the longitudinal direction X, i.e., the width direction Y. In addition, Figure 5 In (B), the longitudinal direction X is indicated by an arrow X at both ends, and the width direction Y is indicated by an arrow Y at both ends.

[0100] The second forming hole 73B is formed in a substantially rectangular shape extending elongatedly along the length direction X. More specifically, the second forming hole 73B is formed in a rectangular shape such that the corners of the four corners of the rectangle are arc-shaped. In addition, in the present embodiment, the second stamping and drawing process S2 constitutes the final stamping and drawing process. Therefore, the shape of the second forming hole 73B is a shape corresponding to the cross-sectional shape of the square tube-shaped bottomed container finally manufactured through the multiple stamping and drawing processes in the manufacturing method of the bottomed container of the present embodiment.

[0101] Reference Figure 5(A), the punch 74B is formed into a shape corresponding to the die 72B. That is, the outer peripheral shape of the punch 74B is formed into a shape corresponding to the second forming hole 73B of the die 72B. Therefore, the punch 74B is formed into a substantially rectangular cross-sectional shape extending elongated in a direction parallel to the longitudinal direction X of the second forming hole 73B.

[0102] The second stamping section of the stamping system 1 includes a second die 71B having a die 72B, and a second stamping and drawing process S2 is performed using the second die 71B, wherein the die 72B has a second forming hole 73B in the shape of an elongated hole as the forming hole 73. In addition, the second stamping and drawing process S2 in the method for manufacturing a bottomed container of the present embodiment is performed using a second die 71B including a die 72B, wherein the die 72B has a second forming hole 73B in the shape of an elongated hole in a substantially rectangular shape as the forming hole 73. The second stamping and drawing process S2 is performed using the die 72B and a punch 74B having a cross-sectional shape corresponding to the second forming hole 73B, wherein the die 72B is provided with a second forming hole 73B in the shape of an elongated hole in a substantially rectangular shape. In the second stamping and drawing process S2, stamping and drawing is performed using the die 72B and the punch 74B on the cylindrical workpiece W2 formed by the first stamping and drawing process S1. In addition, in Figure 5 (B) and Figure 5 In (C), the workpiece W2 is shown by a two-dot chain line.

[0103] In the second stamping and drawing process S2 in the method for manufacturing a bottomed container of the present embodiment and the second stamping and drawing process S2 performed by the second stamping section of the stamping system 1, the punch 74B presses the workpiece W2 into the second forming hole 73B of the die 72B, thereby forming the workpiece W2 into a square cylindrical container with a bottom, i.e., the workpiece W3 serving as the workpiece W. By performing the second stamping and drawing process S2, a square cylindrical container with a bottom formed as the square cylindrical workpiece W3 is manufactured. Figure 6 In (C), a square tube-shaped bottomed container formed into a workpiece W3 after the second stamping and drawing process S2 is shown in a three-dimensional view. Figure 6In (C), the upper end of the workpiece W3 is schematically represented in a flat state. In the present embodiment, the second stamping and drawing process S2 constitutes the final stamping and drawing process. Therefore, the workpiece W3 formed by the second stamping and drawing process S2 is formed into the shape of a bottomed container manufactured by multiple stamping and drawing processes of the method for manufacturing a bottomed container of the present embodiment, and constitutes a square cylindrical bottomed container with a bottom manufactured by the method for manufacturing a bottomed container of the present embodiment. In addition, in the following description, the square cylindrical bottomed container with a bottom manufactured by performing the second stamping and drawing process S2 to form the workpiece W3 is sometimes referred to as a bottomed container W3.

[0104] Here, the relationship between the shapes of the forming holes 73 of the die 72 in the first stamping and drawing process S1 and the second stamping and drawing process S2 is further described. In addition, the following description of the relationship between the shapes of the forming holes 73 of the die 72 is a description of the relationship between the shapes of the forming holes 73 of the die 72 in the first stamping and drawing process S1 and the second stamping and drawing process S2 in the manufacturing method of the bottomed container of the present embodiment, and is also a description of the shapes of the forming holes 73 of the die 72 of the first stamping part that performs the first stamping and drawing process S1 and the second stamping part that performs the second stamping and drawing process S2 in the stamping system 1. Figure 7 This is a diagram that schematically shows the formed hole 73 of the die 72 used in the first stamping and drawing process S1 and the second stamping and drawing process S2 in the manufacturing method of the bottomed container of this embodiment, and is a diagram that schematically shows the formed hole 73 of the die 72 used in the first stamping and drawing process S1 and the second stamping and drawing process S2 performed by the first stamping part and the second stamping part in the stamping system 1. That is, in Figure 7 In the figure, the first forming hole 73A of the die 72A used in the first stamping and drawing process S1 and the second forming hole 73B of the die 72B used in the second stamping and drawing process S2 are compared and schematically shown, and the first forming hole 73A of the die 72A of the first stamping part and the second forming hole 73B of the die 72B of the second stamping part in the stamping system 1 are compared and schematically shown. In addition, of course, the die 72A and the die 72B are not the same die 72, but different dies 72, but in Figure 7 In the figure, in order to compare the first formed hole 73A and the second formed hole 73B, the die 72A and the die 72B are schematically illustrated in an overlapping state.

[0105] Reference Figure 7, the area of ​​the first forming hole 73A is larger than the area of ​​the second forming hole 73B throughout the entire circumference of the area. That is, in a state where the die 72A and the die 72B are overlapped, in a plan view, the outline of the first forming hole 73A and the outline of the second forming hole 73B do not overlap, and the second forming hole 73B is arranged inside the first forming hole 73A. Therefore, the first forming hole 73A is formed to have a larger dimension in the width direction Y perpendicular to the length direction X, i.e., the length direction X, which is the direction extending in the shape of a long hole, than the second forming hole 73B. Further, the first forming hole 73A is formed to have a larger dimension in the width direction Y, i.e., the entire length of the direction in which the first forming hole 73A passes through the die 72A, i.e., the vertical direction, than the second forming hole 73B. More specifically, first, the second forming hole 73B is in a substantially rectangular shape, and the dimension in the width direction Y, i.e., the width dimension YB, of the second forming hole 73B is set to a constant dimension. Furthermore, the width dimension YB of the second formed hole 73B is set to a constant dimension throughout the entire length of the second formed hole 73B in the direction in which the second formed hole 73B passes through the die 72B, that is, in the vertical direction. On the other hand, regarding the first formed hole 73A, the semicircular arc-shaped portions at both ends in the longitudinal direction X are formed to have a size that surrounds both ends in the longitudinal direction of the second formed hole 73B on the outside throughout the entire length in the vertical direction. Furthermore, the first formed hole 73A is formed so that the dimension in the width direction Y gradually decreases from both ends in the longitudinal direction X to the center in the circumferential direction except for the both ends in the longitudinal direction X throughout the entire length in the vertical direction, and becomes the smallest width dimension YA at the center position CX in the longitudinal direction X. Furthermore, in the portion other than the both ends in the longitudinal direction X of the first formed hole 73A, the width dimension YA of the portion with the smallest dimension in the width direction Y is formed to be larger than the width dimension YB of the second formed hole 73B. Therefore, the first formed hole 73A is formed to have a larger dimension in the width direction Y perpendicular to the longitudinal direction X in the direction in which the long hole extends over the entire length in the up-down direction than the second formed hole 73B.

[0106] (The first stamping and drawing process and the role of the first stamping part)

[0107] Next, the role of the first stamping and drawing process S1 in the manufacturing method of the bottomed container of the present embodiment and the role of the first stamping section that performs the first stamping and drawing process S1 in the stamping system 1 are described. In addition, the description of the following role is a description of the role of the first stamping and drawing process S1 in the manufacturing method of the bottomed container of the present embodiment, and is also a description of the role of the first stamping section that performs the first stamping and drawing process S1 in the stamping system 1. Figure 81 is a diagram for explaining the force acting on the workpiece W in the first stamping and drawing process S1 in the method for manufacturing a bottomed container of the present embodiment, and is a diagram for explaining the force acting on the workpiece W in the first stamping and drawing process S1 performed by the first stamping part of the stamping system 1. Figure 8 , schematically shows a workpiece W, i.e., workpiece W1, in the middle of a stamping and drawing process S1 of the first stamping and drawing process in the method for manufacturing a bottomed container of the present embodiment, and schematically shows a workpiece W, i.e., workpiece W1, in the middle of a stamping and drawing process S1 of the first stamping part of the stamping system 1. Figure 8 In the figure, the die 72A and the punch 74A are omitted, and the first formed hole 73A is schematically illustrated by a two-dot chain line.

[0108] Reference Figure 8 When the first stamping and drawing process S1 is started, the workpiece W1 placed on the die 72A is pressed into the first forming hole 73A by the punch 74A. When the workpiece W1 is pressed into the first forming hole 73A, a compressive force is generated in the circumferential direction of the first forming hole 73A for the workpiece W1 in the semicircular arc-shaped areas at both ends of the length direction X of the first forming hole 73A. Figure 8 and the following Fig.10 In (A), the two end arrows P1 of the single dotted line indicate the portions of the workpiece W1 processed at the two end sides in the length direction X of the first forming hole 73A, and this portion is hereinafter also referred to as "the two end side processed portions P1". The two end side processed portions P1 of the workpiece W1 are in a shrink flange forming state, and thus a compressive force is generated in the circumferential direction.

[0109] On the other hand, when the workpiece W1 is pressed into the first forming hole 73A, a drawing force is generated in the circumferential direction of the first forming hole 73A in the portion of the workpiece W1 that is processed in the central region other than the two ends in the longitudinal direction X of the first forming hole 73A. Figure 8 and the following Fig.10 In (A), the arrows P2 at both ends of the single-dot chain line indicate the portion of the workpiece W1 processed in the central area other than the two ends of the first forming hole 73A in the longitudinal direction X. This portion is hereinafter referred to as "central side processed portion P2". The central side processed portion P2 of the workpiece W1 is in a stretched flange forming state, so a drawing force is generated in the circumferential direction.

[0110] As described above, in the first stamping and drawing process S1, for the workpiece W1, a compressive force is generated in the circumferential direction at the end side processing parts P1, and a drawing force is generated in the circumferential direction at the central side processing part P2. Therefore, for the workpiece W1, the circumferential drawing force generated in the central side processing part P2 counteracts the circumferential compressive force generated in the end side processing parts P1. As a result, on the workpiece W1, plastic flow is smoothly generated from the end side processing parts P1 side where the compressive force is generated to the central side processing part P2 side where the drawing force is generated, and the workpiece W1 is stamped between the die 72A and the punch 74A to form the workpiece W1 into the shape of the workpiece W2. In addition, in the first stamping and drawing process S1, plastic flow is smoothly generated from the end side processing parts P1 side where the compressive force is generated to the central side processing part P2 side where the drawing force is generated, thereby suppressing the excess volume of the material in the central side processing part P2, and suppressing the plastic flow to the bottom side of the part formed into the shape of the workpiece W2. Thus, when the workpiece W1 is formed into the workpiece W2 through the first press-drawing step S1 , it is possible to suppress the occurrence of deformation on the bottom side of the workpiece W2 at the center side portion in the longitudinal direction X.

[0111] Here, the effect of suppressing deformation of the bottom of the workpiece W2 formed in the first press-drawing process S1 will be further described in comparison with a conventional press-drawing process. Fig. 9 It is a diagram for explaining the conventional stamping and drawing process, wherein: Fig. 9 (A) is a top view showing the die 172A. Fig. 9 (B) is a cross-sectional view showing a state where the workpiece W101 is subjected to drawing to form the workpiece W102. Fig. 9 (C) is to Fig. 9 This is a diagram showing an enlarged view of the D portion surrounded by a dotted line in (B). Fig. 9 The conventional press-drawing process described here constitutes the first press-drawing process in a conventional method for manufacturing a container with a bottom, which manufactures a rectangular cylindrical container with a bottom by performing a plurality of press-drawing processes to form a workpiece W101 in a flat plate state.

[0112] Reference Fig. 9 The conventional stamping and drawing process is performed using a die 172A having a long hole-shaped forming hole 173A and a punch 174A corresponding to the die 172A. The forming hole 173A of the die 172A is formed so that the dimension of the long hole-shaped extending direction, i.e., the length direction X, is larger than the dimension of the width direction Y, i.e., the direction perpendicular to the length direction X. Fig. 9In (A), the length direction X is indicated by the arrow X at both ends, and the width direction Y is indicated by the arrow Y at both ends. In addition, the forming hole 173A of the die 172A is formed in a shape that expands outward in an elliptical shape throughout the entire circumference. The punch 174A is formed in a shape corresponding to the forming hole 173A of the die 172A. That is, the outer peripheral shape of the punch 174A is formed in a shape that expands outward in an elliptical shape throughout the entire circumference, similar to the shape of the forming hole of the die 172A.

[0113] In the conventional stamping and drawing process, the workpiece W101 in a flat plate state is subjected to stamping and drawing using the die 172A and the punch 174A. Fig. 9 (A) and Fig. 9 In (B), the workpiece W101 is shown by a two-dot chain line. In the conventional stamping and drawing process, the punch 174A presses the workpiece W101 into the forming hole 173A of the die 172A, thereby forming the workpiece W101 into a cylindrical workpiece W102 having a bottom (see Fig. 9 (B)). When the workpiece W101 is pressed into the forming hole 173A, a circumferential compressive force is generated on the workpiece W101 over the entire circumference. That is, in the existing stamping and drawing process, the workpiece 101 is formed by the forming hole 173A that expands outward in an elliptical shape over the entire circumference. Therefore, in the workpiece W101, a compressive force is generated not only in the parts processed on the two end sides of the forming hole 173A in the length direction X, but also in the parts processed in the central area of ​​the forming hole 173A in the length direction X. In addition, in Fig. 9 In (A), the portions of the workpiece W101 processed at both end sides in the longitudinal direction X of the forming hole 173A are indicated by the single-dot chain line arrows P10, and hereinafter, such portions are also referred to as "end side processed portions P10". Furthermore, the portions of the workpiece W101 processed at the central side region of the forming hole 173A are indicated by the single-dot chain line arrows P20, and hereinafter, such portions are also referred to as "central side processed portions P20".

[0114] In the existing stamping and drawing process, for the workpiece W101, a circumferential compressive force is generated throughout the entire circumference of the forming hole 173A, and a circumferential compressive force is generated in both the end side processing parts P10 and the center side processing part P20. However, with respect to the long hole-shaped forming hole 173A that extends outward in an elliptical shape throughout the entire circumference, since the curvature of the two end parts in the length direction X is larger than the curvature of the central side part in the length direction X, the processing amount of the end side processing parts P10 is larger than the processing amount of the center side processing part P20. Therefore, plastic flow occurs from the end side processing parts P10 to the center side processing part P20, and the volume of the material of the center side processing part P20 is excessive. Therefore, the material of the center side processing part P20 with an excess volume plastically flows to the bottom side of the workpiece W102 that is not constrained by the die 172A and the punch 174A. As a result, as Fig. 9 (B) and Fig. 9 As shown in (C), in the existing stamping and drawing process, a part of the central side portion in the length direction X of the bottom of the workpiece W102 subjected to the stamping and drawing process is likely to be separated from the punch 174A and bulge out, and deformation is likely to occur at the bottom of the workpiece W102 in the central side portion in the length direction X.

[0115] On the other hand, in the first stamping and drawing step S1 in the method for manufacturing a bottomed container of the present embodiment and the first stamping and drawing step S1 performed by the first stamping part of the stamping system 1, deformation of the bottom of the workpiece W2 formed by the first stamping and drawing step S1 is suppressed. Fig.10 It is a diagram for explaining the first stamping and drawing process S1 in the method for manufacturing a bottomed container according to the present embodiment and the first stamping and drawing process S1 performed by the first stamping unit of the stamping system 1, and, Fig.10 (A) is a top view showing the die 72A. Fig.10 (B) is a cross-sectional view showing a state where the workpiece W1 is subjected to drawing to form the workpiece W2. Fig.10 (C) is to Fig.10 This is an enlarged view of part F surrounded by a dotted line in (B).

[0116] Reference Fig.10 The first stamping and drawing process S1 is performed using a die 72A and a punch 74A corresponding to the die 72A. The die 72A is provided with a first forming hole 73A. The first forming hole 73A is formed into a shape that narrows from both end sides in the length direction X to the center side and toward the inner side in the width direction Y. In the first stamping and drawing process S1, a stamping and drawing process using the die 72A and the punch 74A is performed on the workpiece W1 in a flat plate state. In addition, the punch 74A presses the workpiece W1 into the first forming hole 73A of the die 72A, thereby forming the workpiece W1 into a cylindrical workpiece W2 having a bottom (refer to Fig.10 (B)). When the workpiece W1 is pressed into the first forming hole 73A, the portions P1 are processed on both ends of the workpiece W1, and a compressive force is generated in the circumferential direction of the first forming hole 73A. On the other hand, when the workpiece W1 is pressed into the first forming hole 73A, the portion P2 is processed on the center side of the workpiece W1, and a tensile force is generated in the circumferential direction of the first forming hole 73A.

[0117] In the first stamping and drawing process step S1, for the workpiece W1, a compressive force is generated in the circumferential direction at the end side processing parts P1, and a drawing force is generated in the circumferential direction at the central side processing part P2. Therefore, for the workpiece W1, the circumferential drawing force generated in the central side processing part P2 counteracts the circumferential compressive force generated in the end side processing parts P1. As a result, on the workpiece W1, plastic flow is smoothly generated from the end side processing parts P1 side where the compressive force is generated to the central side processing part P2 side where the drawing force is generated, and the workpiece W1 is stamped between the die 72A and the punch 74A to form the workpiece W1 into the shape of the workpiece W2. That is, the material that plastically flows from the end side processing parts P1 side where the compressive force is generated to the central side processing part P2 side where the drawing force is generated will not have excess volume in the central side processing part P2, and is used to form the central side processing part P2. Thus, in the first stamping and drawing process S1, plastic flow occurs smoothly from the end processing parts P1 side where the compressive force is generated to the central processing part P2 side where the drawing force is generated, thereby suppressing the excess volume of the material in the central processing part P2 and suppressing the plastic flow to the bottom side of the part formed into the shape of the workpiece W2. Fig.10 (B) and Fig.10 As shown in (C), in the first stamping and drawing process S1, the central side portion of the length direction X of the bottom of the workpiece W2 subjected to the stamping and drawing process is not easily separated from the punch 74A, and has a shape that is substantially the same as the punch 74A or a shape that is quite close to the shape of the punch 74A. Therefore, in the first stamping and drawing process S1, deformation of the bottom side of the workpiece W2 in the central side portion in the length direction X is suppressed.

[0118] As described above, according to the manufacturing method of the bottomed container of the present embodiment, a square tube-shaped bottomed container W3 having a bottom is manufactured by performing the first stamping and drawing process S1 and the second stamping and drawing process S2. Here, the appearance features of the bottomed container W3 manufactured by the manufacturing method of the bottomed container of the present embodiment are described. Fig.11 2 is a diagram for explaining the appearance characteristics of the manufactured bottomed container. Fig.11 (A) is a diagram for explaining the appearance features of a container with a bottom W103 manufactured by a conventional method for manufacturing a container with a bottom. Fig.11(B) is a diagram for explaining the external appearance features of the container with a bottom W3 manufactured by the method for manufacturing a container with a bottom according to the present embodiment.

[0119] In the existing method for manufacturing a bottom container, Fig. 9 As shown in FIG. 1 , a workpiece W101 in a flat plate state is first subjected to a stamping and drawing process using a die 172A to form a cylindrical workpiece W102 having an elliptical cross-sectional shape. The die 172A has a forming hole 173A that extends outward in an elliptical shape throughout the entire circumference. Then, a stamping and drawing process using a die (not shown) is performed on the workpiece W102 to form a cylindrical workpiece W102 having an elliptical cross-sectional shape. Fig.11 As shown in (A), a bottomed container W103 having a square tube shape has a bottom, and the punching die has a forming hole formed in the shape of a rectangle with rounded corners at the four corners. Fig.11 As shown in (A), regarding the bottomed container W103 manufactured by the conventional bottomed container manufacturing method, a thin linear pattern Q is generated on the side of the bottomed container W103, which is bent toward the opening side of the upper end of the bottomed container W103. Fig.11 (A) schematically shows the pattern Q generated on the side of the bottomed container W103. On the bottomed container W103, there is no deformation in the portion of the pattern Q, and the pattern Q on the side of the bottomed container W103 appears according to a slight difference in the reflection condition of light on the side of the bottomed container W103. In the conventional method for manufacturing a bottomed container, a square cylindrical bottomed container W103 is formed by stamping and drawing a cylindrical workpiece W102 having an elliptical cross-sectional shape. Therefore, when the corner portion of the bottom of the workpiece W102 is drawn again, the central portion of the elliptical shape in the long axis direction of the portion extending in the short axis direction of the elliptical shape extends while plastically flowing in a large extent in the up-down direction, and a thin linear pattern Q is generated on the bottomed container W103 that is bent in a manner approaching the opening side of the upper end of the bottomed container W103.

[0120] On the other hand, Fig.11 As shown in (B), on the bottomed container W3 manufactured by the manufacturing method of the bottomed container of this embodiment, a thin linear pattern R is generated on the side of the bottomed container W3, and the pattern R extends while smoothly bending in a direction substantially parallel to the longitudinal direction X, and is slightly bent in a manner that it slightly approaches the bottom side of the bottomed container W3 in the central part of the longitudinal direction X. Fig.11In (B), the pattern R generated on the side of the bottomed container W3 is schematically shown. On the bottomed container W3, there is no deformation in the portion of the pattern R, and the pattern R on the side of the bottomed container W3 appears according to a slight difference in the reflection condition of light on the side of the bottomed container W3. In the manufacturing method of the bottomed container of the present embodiment, when the second stamping and drawing process S2 is performed, the corner portion of the bottom of the workpiece W2 moves toward the side of the bottomed container W3 (workpiece W3) due to plastic flow. The corner portion of the bottom of the workpiece W2 is a portion that is bent once, so when it moves to the side and extends flatly through the second stamping and drawing process S2, it becomes a state with an appearance different from the surrounding portion that is not bent, and the pattern R appears on the side of the bottomed container W3. Furthermore, the central side portion of the corner portion of the bottom of the workpiece W2 in the longitudinal direction X is formed by the first stamping and drawing process S1 in a manner narrowed inward in the width direction Y, so when it is moved to the side and extended flatly by the second stamping and drawing process S2, as shown in FIG. Fig.11 As shown in (B), a thin linear pattern R appears on the side of the bottomed container W3, and the pattern R extends while smoothly bending in a direction substantially parallel to the longitudinal direction X, and is slightly bent in a manner slightly approaching the bottom side of the bottomed container W3 in the central portion of the longitudinal direction X. In this way, with respect to the square tube-shaped bottomed container W3 manufactured by performing the first stamping and drawing process S1 and the second stamping and drawing process S2, a thin linear pattern R is generated on the side thereof, and the pattern R extends while smoothly bending in a direction substantially parallel to the longitudinal direction X, and is slightly bent in a manner slightly approaching the bottom side of the bottomed container W3 in the central portion of the longitudinal direction X.

[0121] [2-3. Effects of this embodiment]

[0122] According to the manufacturing method and stamping system 1 of the bottom container of the present embodiment, the first forming hole 73A is formed to be narrowed from the two end sides of the length direction X to the central side, toward the inner side of the width direction Y, within the range of the size of the width direction Y larger than the size of the width direction Y of the second forming hole 73B, that is, the width size YB. Thus, in the first stamping and drawing process S1, for the workpiece W1, the part processed on the central side of the length direction X of the first forming hole 73A, that is, the central side processing part P2, is in a state where a drawing force is generated along the circumferential direction of the first forming hole 73A. Therefore, on the workpiece W1, the circumferential drawing force generated in the central side processing part P2 counteracts the compression force generated by the part processed on the two end sides of the length direction X of the first forming hole 73A, that is, the two end side processing part P1. Thus, the excess volume of the material processed on the central side of the length direction X of the first forming hole 73A is suppressed, and the plastic flow to the bottom side of the workpiece W2 is suppressed. In addition, the first forming hole 73A is formed to narrow from the two end sides of the length direction X to the central side toward the inner side of the width direction Y within the range of the dimension of the width direction Y larger than the width dimension YB of the second forming hole 73B over the entire length in the vertical direction. Therefore, the force acting on the workpiece W1 at the two end sides and the central side of the length direction X of the first forming hole 73A can be adjusted throughout the entire length of the first stamping and drawing process S1, and the excess volume of the material processed on the central side of the length direction X of the first forming hole 73A can be suppressed, and the plastic flow to the bottom side of the workpiece W2 can be suppressed. In addition, in the second stamping and drawing process S2, the excess volume on the central side of the length direction X is suppressed, and the plastic flow to the bottom side is suppressed, so that the workpiece W2 in this state passes through the second forming hole 73B whose dimension in the width direction Y is smaller than the dimension in the width direction Y of the first forming hole 73A, and is stamped and drawn to form a square tube-shaped state. In this way, the workpiece W is finally formed into a workpiece W3 in a square tube-shaped state. Thus, according to the manufacturing method and stamping system 1 of the bottom container of the present embodiment, for the workpiece W, in the first stamping and drawing process S1, the excess volume on the central side in the length direction X is suppressed, and the plastic flow to the bottom side is suppressed to perform stamping forming, and in the second stamping and drawing process, the workpiece W is drawn along the width direction Y and stamped into a square tube-shaped state. Therefore, according to the manufacturing method and stamping system 1 of the bottom container of the present embodiment, for the workpiece W, deformation on the bottom side of the central side portion in the length direction X can be suppressed. In addition, in the manufacturing method and stamping system 1 of the bottom container of the present embodiment, the circumferential drawing force generated in the central side processing part P2 counteracts the circumferential compression force generated in the two end side processing parts P1, so that the central side processing part P2 is not easy to buckle, and the generation of wrinkles can be suppressed. In addition, according to the manufacturing method and stamping system 1 of the bottom container of the present embodiment, deformation on the bottom side of the workpiece W can be suppressed.Therefore, when the ironing step S3 is performed, deformation of the wall portion of the bottomed container as the workpiece W after the ironing step S3 can be suppressed, and dimensional abnormalities of the corner portion of the bottom of the bottomed container can also be suppressed.

[0123] As described above, according to the manufacturing method and stamping system 1 of the bottomed container of the present embodiment, when a square cylindrical bottomed container is manufactured by forming the workpiece W from a flat plate state into a square cylindrical state with a bottom by performing multiple stamping and drawing processes using multiple molds having long hole-shaped forming holes 73, deformation on the bottom side of the workpiece W can be suppressed.

[0124] In addition, in the initial stamping and drawing process of stamping and drawing the workpiece W in a flat state, the compressive force generated by the parts processed on the two end sides of the length direction X of the forming hole 73 also increases. However, according to the manufacturing method and stamping system 1 of the bottomed container of the present embodiment, in the initial stamping and drawing process configured as the first stamping and drawing process S1, a circumferential drawing force can be generated in the central side processing part P2 in a manner that counteracts the circumferential compressive force generated in the processing parts P1 on the two end sides. Therefore, even in the initial stamping and drawing process in which deformation of the bottom side of the workpiece W is easily generated, deformation on the bottom side of the workpiece W can be efficiently suppressed.

[0125] In addition, in the manufacturing method and punching system 1 of the bottom container of the present embodiment, the first forming hole 73A is formed to be bent and narrowed toward the inner side of the width direction Y from the two end sides to the central side in the length direction X, and narrowed to the narrowest inward side of the width direction Y at the central position CX in the length direction X. Thus, according to the manufacturing method and punching system 1 of the bottom container of the present embodiment, a circumferential drawing force can be generated in the central side processing part P2 in a more balanced manner to counter the circumferential compression force generated in the processing parts P1 on the two end sides. Therefore, deformation on the bottom side of the workpiece W can be efficiently suppressed.

[0126] [3. Modifications]

[0127] In the above-mentioned embodiment, an example of a manufacturing method and a stamping system 1 for a bottom container is described as follows, that is, two stamping and drawing processes are performed as multiple stamping and drawing processes, the first stamping and drawing process is constituted as a first stamping and drawing process, and the second stamping and drawing process is constituted as a second stamping and drawing process, but it may not be like this. It is also possible to implement a manufacturing method and a stamping system for a bottom container in which three or more stamping and drawing processes are performed as multiple stamping and drawing processes. In addition, in the manufacturing method and a stamping system for a bottom container in which more than three stamping and drawing processes are performed, it is also possible to implement a manufacturing method and a stamping system for a bottom container in which a first stamping and drawing process and a second stamping and drawing process are performed multiple times. For example, it is possible to implement Fig.12 The method shown.

[0128] Fig.12 The flowchart of the manufacturing method of the bottomed container of the modified example is shown, and the flowchart of multiple punching and drawing processing steps performed by the punching system of the modified example is shown. Fig.12 A modified example of a method for manufacturing a bottomed container is shown, in which a square cylindrical bottomed container having a bottom is formed from a flat workpiece W by performing multiple stamping and drawing processes using multiple dies having long holes. Fig.12 The present invention shows a multiple stamping and drawing process performed in a modified example of a stamping system for forming a square cylindrical bottomed container having a bottom from a workpiece W in a flat plate state by performing multiple stamping and drawing processes using multiple dies having long hole-shaped forming holes. The manufacturing method of the bottomed container of this modified example is implemented, for example, by performing multiple stamping and drawing processes on the workpiece W using a stamping system 1, and the stamping system of this modified example is configured as a stamping system 1 that performs multiple stamping and drawing processes on the workpiece W. Therefore, the manufacturing method of the bottomed container of this modified example is configured as a manufacturing method of the bottomed container as follows, that is, multiple stamping and drawing processes are performed on the workpiece W using multiple dies configured to include a die 72 and a punch 74 and having a long hole-shaped forming hole 73, so that the workpiece W is formed from a flat plate state into a square cylindrical state, thereby manufacturing a square cylindrical bottomed container. Furthermore, the stamping system of this variant is configured as a stamping system 1 as follows, i.e., a plurality of dies configured to include a die 72 and a punch 74 and having a long hole-shaped forming hole 73 are used to perform multiple stamping and drawing processes on the workpiece W, thereby forming the workpiece W from a flat plate state into a square tube-shaped state having a bottom, thereby forming a square tube-shaped container with a bottom.

[0129] The manufacturing method of the bottomed container of this modified example is configured to have three stamping and drawing steps as multiple stamping and drawing steps. In addition, the stamping system of this modified example is configured to perform three stamping and drawing steps as multiple stamping and drawing steps. That is, Fig.12 As shown, the manufacturing method of the bottomed container of the present variant is constructed to include a first stamping and drawing process S11, a second stamping and drawing process S12, and a third stamping and drawing process S13. Furthermore, the stamping system of the present variant is constructed to perform a first stamping and drawing process S11, a second stamping and drawing process S12, and a third stamping and drawing process S13. The first stamping and drawing process S11 is the initial stamping and drawing process. The second stamping and drawing process S12 is a stamping and drawing process that is performed subsequent to the first stamping and drawing process S11. The third stamping and drawing process S13 is the final stamping and drawing process that is performed subsequent to the second stamping and drawing process S12. In addition, although Fig.12 Although the method of performing the ironing and drawing process after the third stamping and drawing process S13 is not illustrated, the ironing and drawing process may be performed after the third stamping and drawing process S13 is completed. That is, the ironing and drawing process for reducing the plate thickness of the wall of the bottomed container by drawing may be performed on the formed square cylindrical container after the first to third stamping and drawing processes S11 to S13 are completed.

[0130] The first stamping and drawing process S11 is a stamping and drawing process excluding the final third stamping and drawing process S13 from the multiple stamping and drawing processes in the manufacturing method of the bottomed container of this modification, and constitutes the first stamping and drawing process of the present invention. In addition, the first stamping and drawing process S11 is a stamping and drawing process excluding the final third stamping and drawing process S13 from the multiple stamping and drawing processes performed by the stamping system of this modification, and constitutes the first stamping and drawing process of the present invention.

[0131] The second stamping and drawing process S12 is the next stamping and drawing process after the first stamping and drawing process among the multiple stamping and drawing processes in the manufacturing method of the bottomed container of this variant, and constitutes the second stamping and drawing process of the present invention. Moreover, the second stamping and drawing process S12 is the next stamping and drawing process after the first stamping and drawing process among the multiple stamping and drawing processes performed by the stamping system of this variant, and constitutes the second stamping and drawing process of the present invention. That is, the second stamping and drawing process S12 is the next stamping and drawing process after the first stamping and drawing process S11 as the first stamping and drawing process, and constitutes the second stamping and drawing process. In addition, the second stamping and drawing process S12 constitutes the second stamping and drawing process relative to the first stamping and drawing process S11, but constitutes the first stamping and drawing process relative to the third stamping and drawing process S13. Specifically, the second stamping and drawing process S12 is a stamping and drawing process excluding the final third stamping and drawing process S13 from the multiple stamping and drawing processes, and constitutes the first stamping and drawing process of the present invention relative to the third stamping and drawing process S13.

[0132] The third stamping and drawing process S13 is the next stamping and drawing process after the first stamping and drawing process among the multiple stamping and drawing processes in the manufacturing method of the bottomed container of this variant, and constitutes the second stamping and drawing process of the present invention. Moreover, the third stamping and drawing process S13 is the next stamping and drawing process after the first stamping and drawing process among the multiple stamping and drawing processes performed by the stamping system of this variant, and constitutes the second stamping and drawing process of the present invention. That is, the third stamping and drawing process S13 is the next stamping and drawing process after the second stamping and drawing process S12 as the first stamping and drawing process, and constitutes the second stamping and drawing process. Below, the first to third stamping and drawing processes S11 to S13 are described in more detail.

[0133] Fig.13 1 is a diagram showing an example of a die used in a stamping and drawing process of a method for manufacturing a bottomed container according to this modification, and is a diagram showing an example of a die of a stamping system according to this modification. More specifically, Fig.13 (A) is a plan cross-sectional view of a punch 74C in a die 71C used in the first press-drawing step S11 and a plan view of a die 72C. Fig.13 (B) is a plan cross-sectional view of a punch 74D in a die 71D used in the second press-drawing step S12 and a plan view of a die 72D. Fig.13(C) is a top view of a punch 74E in a die 71E used in the third stamping and drawing process S13 and a top view of a die 72E. In addition, the dies 72C to 72E used in the first to third stamping and drawing processes S11 to S13 are provided with long hole-shaped forming holes 73, respectively. Fig.13 In (A) to (C), the longitudinal direction X, which is the direction in which the formed hole 73 extends in the shape of a long hole, is indicated by an arrow X at both ends, and the width direction Y, which is a direction perpendicular to the longitudinal direction X, is indicated by an arrow Y at both ends.

[0134] Reference Fig.13 (A), the die 71C used in the first stamping and drawing process S11 is configured to include a die 72C and a punch 74C. The die 72C is set as one of the multiple dies 72 installed in the stamping system 1, and is configured as the die 72 used in the first stamping and drawing process S11. The punch 74C is set as one of the multiple punches 74 installed in the stamping system 1, and is configured as the punch 74 used in the first stamping and drawing process S11.

[0135] Reference Fig.13 (A), a forming hole 73C as a long hole-shaped forming hole 73 of the die 72 is provided in the die 72C. That is, a forming hole 73C is provided in the die 72C, which is larger in the length direction X than in the width direction Y and is formed in the shape of a long hole in a plan view. For example, both ends of the forming hole 73C in the length direction X are formed in a semicircular arc shape. In addition, the shape of the portion of the forming hole 73C excluding the two ends in the length direction X in the circumferential direction is formed so as to narrow toward the inside of the width direction Y from the two end sides in the length direction X to the center side. In other words, the shape of the portion of the forming hole 73C excluding the two end sides in the length direction X in the circumferential direction is formed so as to gradually reduce the size in the width direction Y from the two end sides in the length direction X to the center side. In addition, the forming hole 73C is formed so as to narrow toward the inside of the width direction Y from the two end sides in the length direction X to the center side over the entire length in the direction in which the forming hole 73C passes through the die 72C, that is, the up-down direction. The molded hole 73C is formed so as to narrow from both end sides in the longitudinal direction X to the center side, while smoothly curving in an arc shape toward the inside in the width direction Y.

[0136] Reference Fig.13(A), the outer peripheral shape of the punch 74C is formed into a shape corresponding to the forming hole 73C of the die 72C. Therefore, the punch 74C is formed so that both ends in the direction parallel to the length direction X of the forming hole 73C are semicircular cross-sectional shapes. In addition, the shape of the portion of the punch 74C except the two ends of the semicircular cross-sectional shape in the circumferential direction is formed so that it is smoothly curved and concave in an arc shape from the two end sides in the direction parallel to the length direction X of the forming hole 73C to the central side toward the inner side in the direction parallel to the width direction Y of the forming hole 73C.

[0137] In addition, the first stamping and drawing process S11 constitutes the first stamping and drawing process. Therefore, the forming hole 73C constitutes the first forming hole of the present invention, and the die 72C and the punch 74C corresponding to the die 72C constitute the first die of the present invention, and the die 72C is provided with the forming hole 73C as the first forming hole.

[0138] The first stamping and drawing process S11 is performed using a die 71C as a first die having a forming hole 73C as a first forming hole. In the first stamping and drawing process S11, a workpiece W11 in a flat plate state supplied from the workpiece supply device 10 of the stamping system 1 is subjected to stamping and drawing using a die 72C and a punch 74C. Fig.13 In (A), the workpiece W11 in a flat plate state is shown by a two-dot chain line. In the first stamping and drawing process S11, the punch 74C presses the workpiece W11 into the forming hole 73C of the die 72C, thereby forming the workpiece W11 into a workpiece W12 (see Fig.13 (B)). In addition, the workpiece W12 formed by the first stamping and drawing process S11 has a bottom and is formed into a shape extending in a cylindrical shape with a cross-sectional shape corresponding to the shape of the formed hole 73C. Fig.13 In (B), the workpiece W12 in a plan view is shown by a two-dot chain line.

[0139] Reference Fig.13 (B), the die 71D used in the second stamping and drawing process S12 is configured to include a die 72D and a punch 74D. The die 72D is set as one of the multiple dies 72 installed in the stamping system 1, and is configured as the die 72 used in the second stamping and drawing process S12. The punch 74D is set as one of the multiple punches 74 installed in the stamping system 1, and is configured as the punch 74 used in the second stamping and drawing process S12.

[0140] Reference Fig.13(B), a forming hole 73D is provided in the die 72D as the long hole-shaped forming hole 73 of the die 72. That is, the die 72D is provided with a forming hole 73D whose dimension in the longitudinal direction X is larger than the dimension in the width direction Y and which is formed in the shape of a long hole in a plan view. The forming hole 73D is formed in a semicircular arc shape at both ends in the longitudinal direction X, for example. In addition, the shape of the circumferential portion of the forming hole 73D excluding the two ends in the longitudinal direction X is formed so as to be smoothly curved in an arc shape while narrowing toward the inner side in the width direction Y from the two end sides in the longitudinal direction X to the central side. In addition, the forming hole 73D is formed so as to narrow toward the inner side in the width direction Y from the two end sides in the longitudinal direction X to the central side over the entire length in the direction in which the forming hole 73D passes through the die 72D, that is, in the up-down direction. In addition, the formed hole 73D is formed so that the dimension in the width direction Y throughout the length direction X is smaller than the dimension in the width direction Y of the formed hole 73C of the die 72C used in the first stamping and drawing process S11. In addition, the formed hole 73D is formed so that the dimension in the width direction Y throughout the entire length in the up-down direction is larger than the dimension in the width direction Y of the second formed hole 73B. Therefore, the formed hole 73C of the die 72C used in the first stamping and drawing process S11 is formed so that the dimension in the width direction Y throughout the length direction X is larger than the formed hole 73D of the die 72D used in the second stamping and drawing process S12, and the dimension in the width direction Y throughout the entire length in the up-down direction is larger.

[0141] Reference Fig.13 (B), the outer peripheral shape of the punch 74D is formed into a shape corresponding to the forming hole 73D of the die 72D. Therefore, the punch 74D is formed so that both ends in the direction parallel to the length direction X of the forming hole 73D are semicircular cross-sectional shapes. In addition, the shape of the portion of the punch 74D except the two ends of the semicircular cross-sectional shape in the circumferential direction is formed so that it is smoothly curved and concave in an arc shape from the two end sides in the direction parallel to the length direction X of the forming hole 73D to the central side toward the inner side in the direction parallel to the width direction Y of the forming hole 73D.

[0142] In addition, the second stamping and drawing process S12 constitutes a second stamping and drawing process relative to the first stamping and drawing process S11 as the first stamping and drawing process. Therefore, in the relationship with the first stamping and drawing process S11, the forming hole 73D constitutes the second forming hole of the present invention, and the die 72D having the forming hole 73D as the second forming hole and the die 71D having the punch 74D corresponding to the die 72D constitutes the second die of the present invention. In addition, the second stamping and drawing process S12 constitutes the first stamping and drawing process relative to the third stamping and drawing process S13 as the second stamping and drawing process. Therefore, in the relationship with the third stamping and drawing process S13, the forming hole 73D constitutes the first forming hole of the present invention, and the die 71D having the forming hole 73D as the first forming hole and the punch 74D corresponding to the die 72D constitutes the first die of the present invention.

[0143] The second stamping and drawing process S12 is performed relative to the first stamping and drawing process S11 using the die 71D of the second die, and the die 71D serves as the second die having a forming hole 73D serving as the second forming hole. In addition, the second stamping and drawing process S12 is performed relative to the third stamping and drawing process S13 using the die 71D, and the die 71D serves as the first die having a forming hole 73D serving as the first forming hole. In the second stamping and drawing process S12, stamping and drawing is performed using the die 72D and the punch 74D on the cylindrical workpiece W12 formed by the first stamping and drawing process S11. In the second stamping and drawing process S12, the punch 74D presses the workpiece W12 into the forming hole 73D of the die 72D, thereby forming the workpiece W12 into the cylindrical workpiece W13 (refer to Fig.13 (C)). In addition, the workpiece W13 formed by the second stamping and drawing process S12 has a bottom area equal to or smaller than that of the workpiece W12, and is formed into a shape extending in a cylindrical shape with a cross-sectional shape corresponding to the shape of the formed hole 73D. Fig.13 In (C), the workpiece W13 in a plan view is shown by a two-dot chain line.

[0144] Reference Fig.13 (C), the die 71E used in the third stamping and drawing process S13 is configured to include a die 72E and a punch 74E. The die 72E is set as one of the multiple dies 72 installed in the stamping system 1, and is configured as the die 72 used in the third stamping and drawing process S13. The punch 74E is set as one of the multiple punches 74 installed in the stamping system 1, and is configured as the punch 74 used in the third stamping and drawing process S13.

[0145] Reference Fig.13 (C), a forming hole 73E is provided in the die 72E as the long hole-shaped forming hole 73 of the die 72. That is, the die 72E is provided with a forming hole 73E whose dimension in the length direction X is larger than the dimension in the width direction Y and which is formed in the shape of a long hole in a plan view. The forming hole 73E is formed in a substantially rectangular shape extending slenderly along the length direction X. More specifically, the forming hole 73E is formed in a shape in which the corners of the four corners of the rectangle are arc-shaped. In addition, the forming hole 73E is formed so that the dimension in the width direction Y is smaller throughout the length direction X than the forming hole 73D of the die 72D used in the second stamping and drawing process step S12. Furthermore, the forming hole 73E is formed so that the dimension in the width direction Y is smaller than the dimension in the width direction Y of the forming hole 73D throughout the entire length in the direction in which the forming hole 73E passes through the die 72E, that is, the up-down direction. Therefore, the forming hole 73D of the punch 72D used in the second punching and drawing process S12 is formed to have a larger dimension in the width direction Y over the length direction X, and a larger dimension in the width direction Y over the entire length in the up-down direction, compared to the forming hole 73E of the punch 72E used in the third punching and drawing process S13. In addition, in this modified example, the third punching and drawing process S13 constitutes the final punching and drawing process. Therefore, the shape of the forming hole 73E is a shape corresponding to the cross-sectional shape of the square tube-shaped bottomed container that is finally manufactured through the multiple punching and drawing processes in the manufacturing method of the bottomed container of this modified example.

[0146] Reference Fig.13 (C), the outer peripheral shape of the punch 74E is formed to correspond to the shape of the forming hole 73E of the die 72E. Therefore, the punch 74E is formed to have a substantially rectangular cross-sectional shape extending elongated in a direction parallel to the longitudinal direction X of the forming hole 73B.

[0147] In addition, the third stamping and drawing process S13 constitutes a second stamping and drawing process relative to the second stamping and drawing process S12 as the first stamping and drawing process. Therefore, the forming hole 73E constitutes the second forming hole of the present invention, and the die 72E having the forming hole 73E as the second forming hole and the die 71E having the punch 74E corresponding to the die 72E constitutes the second die of the present invention.

[0148] The third stamping and drawing process S13 is performed using a die 71E as a second die having a forming hole 73E as a second forming hole relative to the second stamping and drawing process S12. In the third stamping and drawing process S13, the cylindrical workpiece W13 formed by the second stamping and drawing process S12 is subjected to stamping and drawing using a die 72E and a punch 74E. In the third stamping and drawing process S13, the punch 74E presses the workpiece W13 into the forming hole 73E of the die 72E, thereby forming the workpiece W13 into a square cylindrical bottomed container having a bottom, namely, the workpiece W. By performing the third stamping and drawing process S13, a square cylindrical bottomed container formed into a square cylindrical workpiece W is manufactured. In addition, in this modified example, the third stamping and drawing process S13 constitutes the final stamping and drawing process. Therefore, the workpiece W formed by the third stamping and drawing process S13 is formed into the shape of a bottomed container manufactured through multiple stamping and drawing processes in the manufacturing method of a bottomed container of this variant example, and constitutes a square cylindrical bottomed container with a bottom manufactured by the manufacturing method of a bottomed container of this variant example.

[0149] Here, the relationship between the shapes of the formed holes 73 of the die 72 in the first stamping and drawing step S11 , the second stamping and drawing step S12 , and the third stamping and drawing step S13 will be further described. Fig.14 1 is a diagram schematically showing a comparison of the formed holes 73 of the die 72 used in the multiple stamping and drawing process in the manufacturing method of the bottomed container of the modified example, and is a diagram schematically showing a comparison of the formed holes 73 of the die 72 used in the multiple stamping and drawing process performed by the stamping system of the modified example. More specifically, in Fig.14 In FIG. 1 , the formed hole 73C of the punch 72C used in the first punching and drawing process S11, the formed hole 73D of the punch 72D used in the second punching and drawing process S12, and the formed hole 73E of the punch 72E used in the third punching and drawing process S13 are compared and schematically shown. In addition, of course, the punch 72C, the punch 72D, and the punch 72E are not the same punch 72, but are different punches 72. However, in FIG. 1 , the punch 72C, the punch 72D, and the punch 72E are different punches 72. Fig.14 In the figure, the die 72C, the die 72D, and the die 72E are schematically shown in an overlapping state in order to compare the forming hole 73C, the forming hole 73D, and the forming hole 73E.

[0150] First, the relationship between the shapes of the forming hole 73C of the die 72C used in the first stamping and drawing process S11 and the forming hole 73D of the die 72D used in the second stamping and drawing process S12 is described. In the relationship between the first stamping and drawing process S11 as the first stamping and drawing process and the second stamping and drawing process S12 as the second stamping and drawing process, the forming hole 73C constitutes the first forming hole, and the forming hole 73D constitutes the second forming hole. Fig.14 , the area of ​​the forming hole 73C constituting the first forming hole is larger than the area of ​​the forming hole 73D constituting the second forming hole throughout the entire circumference of the area. That is, in a state where the die 72C and the die 72D are overlapped, in a plan view, the contour of the forming hole 73C and the contour of the forming hole 73D do not overlap, and the forming hole 73D is arranged on the inner side of the forming hole 73C. Therefore, the forming hole 73C constituting the first forming hole is formed to have a larger dimension in the width direction Y than the forming hole 73D constituting the second forming hole throughout the length direction X. Furthermore, the forming hole 73C constituting the first forming hole is formed to have a larger dimension in the width direction Y than the forming hole 73D constituting the second forming hole throughout the entire length of the direction in which the forming hole 73C passes through the die 72C, that is, the vertical direction. More specifically, with respect to the forming hole 73C, the semicircular arc-shaped portions at both ends in the length direction X are formed to have a size that surrounds the semicircular arc-shaped portions at both ends in the length direction X of the forming hole 73D on the outside throughout the entire length in the vertical direction. Furthermore, the portion of the formed hole 73C that is formed to be narrowed from both ends in the longitudinal direction X to the center side toward the inner side in the width direction Y is formed to have a size that surrounds the portion of the formed hole 73D that is formed to be narrowed from both ends in the longitudinal direction X to the center side toward the inner side in the width direction Y over the entire length in the vertical direction. Therefore, the formed hole 73C constituting the first formed hole is formed to have a larger dimension in the width direction Y over the entire length in the vertical direction than the formed hole 73E constituting the second formed hole.

[0151] Next, the relationship between the shapes of the formed hole 73D of the die 72D used in the second stamping and drawing process S12 and the formed hole 73E of the die 72E used in the third stamping and drawing process S13 is described. In the relationship between the second stamping and drawing process S12 as the first stamping and drawing process and the third stamping and drawing process S13 as the second stamping and drawing process, the formed hole 73D constitutes the first formed hole, and the formed hole 73E constitutes the second formed hole. Fig.14, the area of ​​the forming hole 73D constituting the first forming hole is larger than the area of ​​the forming hole 73E constituting the second forming hole throughout the entire circumference of the area. That is, in a state where the die 72D and the die 72E are overlapped, in a plan view, the contour of the forming hole 73D and the contour of the forming hole 73E do not overlap, and the forming hole 73E is arranged on the inner side of the forming hole 73D. Therefore, the forming hole 73D constituting the first forming hole is formed so that the dimension in the width direction Y is larger throughout the length direction X than the forming hole 73E constituting the second forming hole. Furthermore, the forming hole 73D constituting the first forming hole is formed so that the dimension in the width direction Y is larger throughout the entire length of the forming hole 73D penetrating the die 72D, that is, the vertical direction, than the forming hole 73E constituting the second forming hole. More specifically, first, the forming hole 73E is in a substantially rectangular shape, and the dimension in the width direction Y of the forming hole 73E, that is, the width dimension YE, is set to a constant dimension. Furthermore, the width dimension YE of the forming hole 73E is set to a constant dimension throughout the entire length of the forming hole 73E in the direction in which the forming hole 73E passes through the die 72E, that is, in the vertical direction. On the other hand, regarding the forming hole 73D, the semicircular arc-shaped portions at both ends in the longitudinal direction X are formed to have a size that surrounds both ends in the longitudinal direction of the forming hole 73E on the outside throughout the entire length in the vertical direction. Furthermore, the forming hole 73D is formed so that the dimension in the width direction Y gradually decreases from both ends to the center in the longitudinal direction X in the circumferential direction except for the both ends in the longitudinal direction X throughout the entire length in the vertical direction, and becomes the smallest width dimension YD at the center position in the longitudinal direction X. Furthermore, in the portion other than the both ends in the longitudinal direction X of the forming hole 73D, the width dimension YD of the portion with the smallest dimension in the width direction Y is formed to be larger than the width dimension YE of the forming hole 73E throughout the entire length in the vertical direction. Therefore, the forming hole 73D constituting the first forming hole is formed so that the dimension in the width direction Y is larger throughout the entire length in the vertical direction than the forming hole 73E constituting the second forming hole.

[0152] According to the manufacturing method and stamping system of the bottomed container of the present modified example described above, the forming hole 73C of the punch 72C used in the first punching and drawing process S11 is formed to be narrowed from the two end sides to the central side in the length direction X toward the inner side of the width direction Y within the range where the size in the width direction Y is larger than the size in the width direction Y of the forming hole 73D of the punch 72D used in the second punching and drawing process S12. As a result, in the first punching and drawing process S11, the portion processed on the central side in the length direction X of the forming hole 73C on the workpiece W11 is in a state where a drawing force is generated along the circumferential direction of the forming hole 73C. Therefore, on the workpiece W11, the drawing force generated on the central side in the length direction X of the forming hole 73C counteracts the compressive force generated on the two end sides in the length direction X of the forming hole 73C. As a result, the excess volume of the material processed on the central side of the forming hole 73C is suppressed, and the plastic flow to the bottom side of the workpiece W12 is suppressed. Therefore, in the workpiece W12 , it is possible to suppress the occurrence of deformation on the bottom side of the center portion in the longitudinal direction X.

[0153] Further, according to the manufacturing method and stamping system of the bottomed container of this modified example, the forming hole 73D of the punch 72D used in the second punching and drawing process S12 is formed to be narrowed from the two end sides of the length direction X to the central side toward the inner side of the width direction Y within the range where the size of the width direction Y is larger than the size of the width direction Y of the forming hole 73E of the punch 72E used in the third punching and drawing process S13. Thus, in the second punching and drawing process S12, the portion processed on the central side of the length direction X of the forming hole 73D on the workpiece W12 is in a state where a drawing force is generated along the circumferential direction of the forming hole 73D. Therefore, on the workpiece W12, the drawing force generated by the portion processed on the central side of the length direction X of the forming hole 73D counteracts the compression force generated by the portion processed on the two end sides of the length direction X of the forming hole 73D. Thus, the excess volume of the material processed on the central side of the forming hole 73D is suppressed, and the plastic flow to the bottom side of the workpiece W13 is suppressed. Therefore, in the workpiece W13, the occurrence of deformation on the bottom side of the center side portion in the longitudinal direction X can be suppressed.

[0154] As described above, according to the manufacturing method and stamping system of the bottomed container of this variant, when a square cylindrical bottomed container is manufactured by forming the workpiece W from a flat plate state into a square cylindrical state with a bottom by performing multiple stamping and drawing processes using multiple molds with long hole-shaped forming holes 73, deformation on the bottom side of the workpiece W can be suppressed.

[0155] Although the embodiments and modified examples of the present invention have been described above, the present invention is not limited to the above-described embodiments and modified examples, and various changes and applications are possible within the scope described in the claims.

[0156] For example, the first stamping and drawing process and the second stamping and drawing process described in the above-mentioned embodiments and modified examples are not limited to the manufacturing method and stamping system of a bottom container that performs two stamping and drawing processes or three stamping and drawing processes, but can also be applied to the manufacturing method and stamping system of a bottom container that performs four or more stamping and drawing processes. In addition, the first stamping and drawing process and the second stamping and drawing process described in the above-mentioned embodiments and modified examples are not limited to the method of performing multiple stamping and drawing processes by a stamping system 1 having a multi-station stamping device 50 provided with multiple dies, but can also be applied to the method of performing multiple stamping and drawing processes by a stamping system having multiple single-action stamping machines each provided with a die. In addition, in the method of performing multiple stamping and drawing processes by a stamping system having multiple single-action stamping machines, the workpiece can be transported between the multiple stamping machines by an operator or by a workpiece conveyor.

[0157] Description of Reference Numerals

[0158] 1: stamping system; 71A: first die; 71B: second die; 72, 72A, 72B: punching die; 73: forming hole; 73A: first forming hole; 73B: second forming hole; W, W1, W2, W3: workpiece; S1: first stamping and drawing process; S2: second stamping and drawing process.

Claims

1. A method for manufacturing a container with a bottom, wherein a workpiece is formed from a flat plate into a square tube with a bottom by performing a plurality of stamping and drawing processes using a plurality of dies having a long hole-shaped forming hole, thereby manufacturing a square tube-shaped container with a bottom, The method for manufacturing a bottomed container is characterized by comprising: The first stamping and drawing process is performed using a first die including a die and a punch, and is configured to be at least any one of the stamping and drawing processes excluding the final stamping and drawing process from the multiple stamping and drawing processes, wherein: The punching die has a first forming hole in the shape of a long hole as the forming hole, and the punch presses the workpiece into the first forming hole; as well as The second stamping and drawing process is performed using a second die and is configured as a next stamping and drawing process after the first stamping and drawing process in the multiple stamping and drawing processes, wherein the second die has a second forming hole in the shape of a long hole as the forming hole, The first forming hole is formed so that, over the entire length of the first forming hole in the vertical direction that passes through the die, the dimension of the width direction that is perpendicular to the length direction that extends in the shape of the long hole is larger than the dimension of the second forming hole in the width direction that is perpendicular to the length direction that extends in the shape of the long hole. The first forming hole is formed over the entire length in the up-down direction and is narrowed toward the inside in the width direction from both ends to the center in the length direction. The outer peripheral shape of the punch is formed into a shape corresponding to the first forming hole, and the cross-sectional shape of the punch is formed to be curved and concave inwardly in a direction parallel to the width direction from both end sides in a direction parallel to the length direction to the center side.

2. The method for manufacturing a bottomed container according to claim 1, characterized in that: The first stamping and drawing step is configured as a first stamping and drawing step among the plurality of stamping and drawing steps.

3. The method for manufacturing a bottomed container according to claim 1 or 2, characterized in that: The first molded hole is formed to narrow while curving toward the inside in the width direction from both ends to the center in the longitudinal direction, and narrows to the narrowest point toward the inside in the width direction at the center position in the longitudinal direction.

4. A punching system, which forms a square tube-shaped container with a bottom by performing multiple punching and drawing processes using multiple dies with long hole-shaped forming holes to form a workpiece from a flat plate state into a square tube-shaped state with a bottom, thereby forming a square tube-shaped container with a bottom, The punching system is characterized by: The first stamping part has a first die including a die and a punch, and uses the first die to perform a first stamping and drawing process, wherein: The punching die has a first forming hole in the shape of a long hole as the forming hole, the punch presses the workpiece into the first forming hole, and the first stamping and drawing process is composed of at least any one of the stamping and drawing processes excluding the final stamping and drawing process from the multiple stamping and drawing processes; and A second stamping part, which has a second die, and uses the second die to perform a second stamping and drawing process, wherein the second die has a second forming hole in the shape of a long hole as the forming hole, and the second stamping and drawing process is constituted as the next stamping and drawing process after the first stamping and drawing process in the multiple stamping and drawing processes, The first forming hole is formed so that, over the entire length of the first forming hole in the vertical direction that passes through the die, the dimension of the width direction that is perpendicular to the length direction that extends in the shape of the long hole is larger than the dimension of the second forming hole in the width direction that is perpendicular to the length direction that extends in the shape of the long hole. The first forming hole is formed over the entire length in the up-down direction and is narrowed toward the inside in the width direction from both ends to the center in the length direction. The outer peripheral shape of the punch is formed into a shape corresponding to the first forming hole, and the cross-sectional shape of the punch is formed to be curved and concave inwardly in a direction parallel to the width direction from both end sides in a direction parallel to the length direction to the center side.

5. The punching system according to claim 4, characterized in that: The first stamping section performs the first stamping and drawing process using the first die, and the first stamping and drawing process is configured as a first stamping and drawing process in the plurality of stamping and drawing processes.

6. The punching system according to claim 4 or 5, characterized in that: The first molded hole is formed to narrow while curving toward the inside in the width direction from both ends to the center in the longitudinal direction, and narrows to the narrowest point toward the inside in the width direction at the center position in the longitudinal direction.

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