Drawing processor

Abstract

To provide a drawing processor which can suppress occurrence of wrinkles and cracking in a molding material even when being used for deep drawing.SOLUTION: A drawing processor 100 comprises: a punch part 10 including a punch 11 which moves in a first direction DR1; and a die 20 including a recess 21A in which a first end 11A of the punch in the first direction is inserted, a first annular surface 21B continuous with an outer peripheral edge of the recess, and a second annular surface 22A which is so arranged as to surround the first annular surface. The punch part includes: a wrinkle pressing part 12 which presses an outer peripheral part of a blank BR against the first annular surface of the die; a die pressing part 13 which has an intermediate part 13B located between the wrinkle pressing part and a second end 11B in the first direction of the punch in the first direction and can contact the second annular surface; a first spring 14 which is telescopically movable in the first direction and is pinched between the wrinkle pressing part and the intermediate part in the first direction; and a second spring 15 which is telescopically movable in the first direction and is pinched between the intermediate part and the other end of the punch in the first direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drawing apparatus for drawing a plate-shaped workpiece. [Background technology]

[0002] In the drawing process of a plate-shaped workpiece such as a blank (when the drawing process is performed multiple times, the first drawing process, i.e., the first drawing or initial drawing process), wrinkles are likely to occur on the outer periphery of the formed material after the drawing process.

[0003] Conventionally, a drawing apparatus equipped with a wrinkle suppressor for suppressing the occurrence of wrinkles is known. JP 2018-043260 A (Patent Document 1) discloses a drawing apparatus equipped with a spring member for pressing a wrinkle suppressor plate against the upper surface of a die plate. This drawing apparatus is configured such that an upper platen is lowered relative to a lower platen to simultaneously lower a punch and a wrinkle suppressor plate, and the punch is inserted into a die hole in the die to perform drawing after the wrinkle suppressor plate comes into contact with a blank arranged on the upper surface of the die plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-043260 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the drawing apparatus described in Patent Document 1, the load applied to the upper platen in order to lower the punch to the bottom dead center after the blank holder plate comes into contact with the blank placed on the upper surface of the die plate is also applied to the blank via the spring member and the blank holder plate.

[0006] When deep drawing is performed using such a drawing apparatus, an excessive load is applied to the blank via the spring member and blank holder plate, which causes a problem of tearing in the formed material.

[0007] In addition, when deep drawing is performed using a drawing device, an excessive load is applied to the spring member, which may eliminate the gap between the coil wires of the spring member, causing adhesion between the wires, in which the wires are pressed together. If adhesion occurs in the spring member, the blank cannot be applied with the load required for wrinkle suppression in the subsequent drawing process, and it is not possible to prevent wrinkles from occurring in the formed material.

[0008] A primary object of the present invention is to provide a drawing apparatus capable of suppressing the occurrence of wrinkles and tears in a formed material even when used for deep drawing. [Means for solving the problem]

[0009] The drawing apparatus according to the present invention is a drawing apparatus for drawing a plate-shaped workpiece. The drawing apparatus includes a punch section including a punch moving in a first direction, a recess into which one end of the punch in the first direction is inserted, a first annular surface connected to the outer periphery of the recess, and a die including a second annular surface arranged to surround the first annular surface. The punch section further includes a blank holder capable of pressing the outer periphery of the workpiece against the first annular surface of the die, a die pressing section having an intermediate portion arranged between the blank holder and the other end of the punch in the first direction in the first direction and capable of contacting the second annular surface, at least one first spring that is expandable and contractable in the first direction and is sandwiched between the blank holder and the intermediate portion in the first direction, and at least one second spring that is expandable and contractable in the first direction and is sandwiched between the intermediate portion and the other end of the punch in the first direction. Effect of the Invention

[0010] According to the present invention, a drawing device can be provided that can suppress the occurrence of wrinkles and tears in a formed material even when used for deep drawing. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view for illustrating a first state of the drawing apparatus according to the present embodiment. [Diagram 2] 2 is a partially enlarged cross-sectional view showing region II in FIG. [Diagram 3] FIG. 4 is a cross-sectional view for illustrating a second state of the drawing apparatus according to the present embodiment. [Figure 4] FIG. 4 is a partially enlarged cross-sectional view showing region IV in FIG. [Diagram 5] FIG. 11 is a cross-sectional view for illustrating a third state of the drawing apparatus according to the present embodiment. [Figure 6] FIG. 6 is a cross-sectional perspective view showing the punch unit shown in FIG. 5. [Figure 7] FIG. 11 is a sectional perspective view for explaining a first modified example of the punch section of the drawing apparatus according to the present embodiment. [Figure 8] FIG. 11 is a sectional perspective view for explaining a second modified example of the punch portion of the drawing apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following, the same or corresponding parts are denoted by the same reference characters, and overlapping descriptions will not be repeated.

[0013] <Structure of drawing equipment> The drawing apparatus according to this embodiment is an apparatus for drawing a plate-shaped workpiece (for example, a blank punched out in a blanking process). Figs. 1 to 6 are diagrams for explaining an example of a drawing apparatus 100 according to this embodiment. The drawing apparatus 100 shown in Figs. 1 to 6 is an apparatus for performing cylindrical deep drawing on a circular blank BR to process the blank BR into a forming material DP (see Fig. 5).

[0014] As shown in FIGS. 1 to 6, a drawing apparatus 100 according to this embodiment includes a punch unit 10, a die 20, and a conveying unit 30. The punch unit 10 includes a punch section 10a, a die 20b, and a conveying section 30c.

[0015] The punch unit 10 includes a punch 11 that moves in a first direction DR1. The central axis of the punch 11 is aligned along the first direction DR1. The first direction DR1 is aligned along the direction of gravity, for example. The drawing apparatus 100 is provided such that the punch 11 moves between a top dead center and a bottom dead center.

[0016] 1 and 2 show a first state which is realized by the punch 11 moving downward from the top dead center. The first state is a state in which application of a blank holder load to the blank BR is started prior to the drawing process. FIGS. 3 and 4 show a second state which is realized by the punch 11 moving further downward from the first state. The second state is a state immediately before the drawing process is performed. FIGS. 5 and 6 show a third state which is realized by the punch 11 moving further downward from the second state. The third state is a state in which the punch 11 has reached the bottom dead center and the drawing process has been performed.

[0017] The punch 11 has a first end 11A located on the die 20 side in the first direction DR1, and a second end 11B located on the opposite side to the first end 11A in the first direction DR1. The shape of the first end 11A of the punch 11 can be appropriately set according to the shape of a molded product to be molded by drawing. The second end 11B has a first flange portion 11C that protrudes outward from a portion extending between the first end 11A and the second end 11B in a radial direction (hereinafter simply referred to as the radial direction) relative to the central axis of the punch 11. The first flange portion 11C is, for example, a separate member from the punch 11, and is fixed to the second end 11B of the punch 11.

[0018] The die 20 includes a recess 21A into which the first end 11A of the punch 11 is inserted, a first annular surface 21B that is continuous with the outer periphery of the recess 21A, and a second annular surface 22A that is arranged to surround the first annular surface 21B. The second annular surface 22A is arranged, for example, closer to the punch section 10 in the first direction DR1 than the first annular surface 21B. The die 20 includes, for example, a first member 21 having the recess 21A and the first annular surface 21B, and a second member 22 (guide die) that is a member separate from the first member 21 and has the second annular surface 22A. The second member 22 is provided to position the blank BR that is transported onto the die 20 by the transport section 19 described later with respect to the recess 21A. The second member 22 has an inner peripheral surface (tapered surface) whose inner diameter decreases downward.

[0019] The conveying section 30 conveys the blank BR from the previous process into the die 20, and conveys the formed material DP after drawing to the next process.

[0020] The punch unit 10 further includes a blank holder 12 , a die pressing unit 13 , a first spring 14 , a second spring 15 , and an outer member 16 .

[0021] The wrinkle suppression unit 12 can press the outer periphery of the blank BR against the first annular surface 21B of the die 20. The wrinkle suppression unit 12 is disposed outside the punch 11 in a radial direction (hereinafter also simply referred to as the radial direction) relative to the central axis of the punch 11. The wrinkle suppression unit 12 is disposed so as to surround the entire circumference of the punch 11 in a circumferential direction (hereinafter also simply referred to as the circumferential direction) relative to the central axis of the punch 11.

[0022] The blank holder 12 has a third end 12A located on the die 20 side in the first direction DR1, and a fourth end 12B located on the opposite side to the third end 12A in the first direction DR1. The third end 12A can press the outer periphery of the blank BR against the first annular surface 21B of the die 20. The third end 12A can come into surface contact with the outer periphery of the blank BR. The fourth end 12B has a second flange 12C that protrudes outward from the third end 12A in the radial direction. The second flange 12C is continuous in the circumferential direction, for example.

[0023] The die pressing portion 13 is capable of contacting the second annular surface 22A of the die 20. The die pressing portion 13 has a cylindrical portion 13A disposed outside the punch 11 and the blank holder 12 in the radial direction, and an intermediate portion 13B disposed between the blank holder 12 and a second end portion 11B of the punch 11 in the first direction DR1.

[0024] The tip end 13A1 of the cylindrical portion 13A located on the die 20 side in the first direction DR1 is capable of contacting the second annular surface 22A of the die 20. The other end of the cylindrical portion 13A located on the opposite side to the tip end 13A1 in the first direction DR1 is fixed to the intermediate portion 13B.

[0025] The cylindrical portion 13A has a third flange portion 13C protruding inward in the radial direction. The third flange portion 13C is disposed closer to the die 20 than the second flange portion 12C of the wrinkle holder 12 in the first direction DR1. The third flange portion 13C is disposed opposite the second flange portion 12C in the first direction DR1. The third flange portion 13C and the second flange portion 12C are disposed to sandwich, for example, a first annular member 17 (first adjustment member). The third flange portion 13C is continuous in, for example, the circumferential direction. The inner diameter of the third flange portion 13C is equal to or larger than the outer diameter of a portion of the wrinkle holder 12 located closer to the third end portion 12A than the second flange portion 12C, and is smaller than the outer diameter of the second flange portion 12C.

[0026] The cylindrical portion 13A further has a fourth flange portion 13D protruding outward in the radial direction. The fourth flange portion 13D is disposed on the opposite side of the die 20 with respect to the third flange portion 13C in the first direction DR1. The fourth flange portion 13D is disposed opposite a fifth flange portion 16D of the outer casing member 16, which will be described later, in the first direction DR1. The fourth flange portion 13D is continuous in, for example, the circumferential direction.

[0027] The intermediate portion 13B is disposed so as to surround the entire circumference of the punch 11 in the circumferential direction. The intermediate portion 13B has an annular portion disposed outside the punch 11 and inside the cylindrical portion 13A in the radial direction. The annular portion of the intermediate portion 13B faces the fourth end portion 12B of the wrinkle holder 12 in the first direction DR1.

[0028] The first spring 14 is expandable and contractable in the first direction DR1. The first spring 14 is sandwiched between the wrinkle suppressor 12 and the middle part 13B of the die pressing part 13 in the first direction DR1. The first spring 14 has a fifth end 14A located on the die 20 side and a sixth end 14B located on the opposite side to the fifth end 14A in the first direction DR1. The fifth end 14A is connected to the fourth end 12B of the wrinkle suppressor 12 via, for example, a second annular member 18 (second adjustment member). The sixth end 14B is directly connected to, for example, the middle part 13B of the die pressing part 13. The first spring 14 biases the wrinkle suppressor 12 toward the die 20 with respect to the die pressing part 13. The maximum value of the load applied by the first spring 14 to the wrinkle suppression portion 12, i.e., the maximum value of the load applied to the first spring 14, is the load (wrinkle suppression load) that the wrinkle suppression portion 12 applies to the blank BR during drawing to suppress the formation of wrinkles in the forming material DP. The load applied to the first spring 14 is maximum when the die pressing portion 13 is in contact with the second annular surface 22A (the second state, the third state, and the transition state between the second state and the third state).

[0029] The first spring 14 is disposed outside the punch 11 in the radial direction and inside the tip portion 13A1 of the die pressing portion 13. The first spring 14 is disposed, for example, coaxially with the punch 11. The central axis of the first spring 14 overlaps with the central axis of the punch 11. The outer diameter of the first spring 14 is equal to or smaller than the inner diameter of the cylindrical portion 13A of the die pressing portion 13.

[0030] The second spring 15 is expandable and contractable in the first direction DR1. The second spring 15 is sandwiched between the intermediate portion 13B of the die pressing portion 13 and the first flange portion 11C of the second end portion 11B of the punch 11 in the first direction DR1. The second spring 15 has a seventh end portion 15A located on the die 20 side and an eighth end portion 15B located on the opposite side to the seventh end portion 15A in the first direction DR1. The seventh end portion 15A is directly connected to, for example, the intermediate portion 13B of the die pressing portion 13. The eighth end portion 15B is directly connected to, for example, the first flange portion 11C of the second end portion 11B of the punch 11. The second spring 15 is arranged, for example, coaxially with the punch 11. The second spring 15 is arranged, for example, coaxially with each of the punch 11 and the first spring 14. Preferably, the outer diameter of the second spring 15 is smaller than the outer diameter of the die pressing portion 13.

[0031] The spring rate (spring constant) of the second spring 15 is different from, for example, the spring rate of the first spring 14. The spring rate of the second spring 15 is lower than, for example, the spring rate of the first spring 14. Note that the spring rate of the second spring 15 may be higher than the spring rate of the first spring 14.

[0032] A second end 11B of the punch 11 is fixed to an outer member 16. The outer member 16 is connected to a driving device (not shown), and moves together with the punch 11 in the first direction DR1 by a driving force applied from the driving device.

[0033] The outer casing member 16 includes, for example, a first outer casing member 16A, a second outer casing member 16B, and a third outer casing member 16C. Each of the first outer casing member 16A and the second outer casing member 16B is a cylindrical member and can accommodate the punch 11, the blank holder 12, the die pressing portion 13, the first spring 14, and the second spring 15 inside. The opening end of the second outer casing member 16B located on the die 20 side in the first direction DR1 is connected to the opening end of the first outer casing member 16A located on the opposite side to the die 20 in the first direction DR1. The opening end of the second outer casing member 16B located on the opposite side to the die 20 in the first direction DR1 is blocked by the third outer casing member 16C.

[0034] The first outer member 16A further has a fifth flange portion 16D that protrudes inward in the radial direction. The fifth flange portion 16D is disposed closer to the die 20 than the fourth flange portion 13D of the die pressing portion 13 in the first direction DR1. The fifth flange portion 16D is continuous in the circumferential direction, for example. The inner diameter of the fifth flange portion 16D is equal to or larger than the outer diameter of a portion of the cylindrical portion 13A that is closer to the tip portion 13A1 than the fourth flange portion 13D, and is smaller than the outer diameter of the fourth flange portion 13D.

[0035] The first annular member 17 and the second annular member 18 are members for adjusting the amount of deflection of the first springs 14 in the first direction DR1 to adjust the load applied by the first springs 14 to the wrinkle suppression sections 12 (i.e., the load applied by the wrinkle suppression sections 12 to the blank BR). The thicknesses of the first annular member 17 and the second annular member 18 are set so that the load applied by the first springs 14 to the wrinkle suppression sections 12 is an appropriate wrinkle suppression load that can suppress the occurrence of wrinkles in the molding material DP.

[0036] The punch section 10 may include only one of the first annular member 17 and the second annular member 18, or may not include the first annular member 17 and the second annular member 18. The fifth end 14A of the first spring 14 may be directly connected to the fourth end 12B of the blank holder 12 without the second annular member 18. The sixth end 14B may be connected to the middle part 13B via an annular member. The seventh end 15A of the second spring 15 may be connected to the middle part 13B of the die pressing part 13 via an annular member. The eighth end 15B may be connected to the first flange part 11C of the second end 11B of the punch 11 via an annular member.

[0037] In the punch unit 10, the wrinkle holder 12 is movable in a first direction DR1 relative to the die pressing unit 13. On the other hand, the lowest point of the wrinkle holder 12 with respect to the die pressing unit 13 is set by a second flange 12C and a third flange 13C facing each other in the first direction DR1. As a result, the first spring 14 is held between a fourth end 12B of the wrinkle holder 12 and a middle portion 13B of the die pressing unit 13.

[0038] In the punch section 10, the punch 11 and the outer member 16 are movable in a first direction DR1 relative to the blank holder 12 and the die pressing section 13. On the other hand, the lowest point of the die pressing section 13 relative to the outer member 16 is set by a fourth flange section 13D and a fifth flange section 16D that face each other in the first direction DR1. As a result, the second spring 15 is held between the middle section 13B of the die pressing section 13 and the first flange section 11C of the second end section 11B of the punch 11.

[0039] In the drawing apparatus 100, in the initial state where the punch 11 is located at the top dead center, an initial load (preload) is applied to the second spring 15. The initial load of the second spring 15 is greater than the maximum load applied to the first spring 14. In other words, the initial load of the second spring 15 is greater than the load applied to the first spring 14 in the state where the die pressing portion 13 is in contact with the second annular surface 22A. When the spring rate of the second spring 15 is lower than the spring rate of the first spring 14, the amount of deflection of the second spring 15 in the initial state is set to be greater than the amount of deflection of the first spring 14 when the second state is reached. On the other hand, when the spring rate of the second spring 15 is higher than the spring rate of the first spring 14, the amount of deflection of the second spring 15 in the initial state can be set arbitrarily as long as the amount of deflection of the second spring 15 at the time when the punch 11 reaches the bottom dead center does not exceed the limit deflection of the second spring 15, and may be, for example, less than or greater than the amount of deflection of the first spring 14 at the time when the second state is reached.

[0040] In the drawing apparatus 100, the punch 11 moves from the top dead center to the bottom dead center, thereby performing deep drawing on the blank BR. As described above, in the drawing apparatus 100, during one stroke in which the punch 11 moves from the top dead center to the bottom dead center, the first state shown in Figures 1 and 2, the second state shown in Figures 3 and 4, and the third state shown in Figures 5 and 6 are sequentially realized.

[0041] When the punch 11 starts to move in the first direction DR1 from the top dead center toward the bottom dead center, the entire punch section 10 moves in the first direction DR1. As a result, the blank holder 12 comes into contact with the outer periphery of the blank BR placed on the first annular surface 21B of the die 20, and the first state is realized. During the above movement, the first spring 14 and the second spring 15 are not compressed as compared to the initial state. In the first state, the die pressing section 13 is not in contact with the second annular surface 22A of the die 20.

[0042] As shown in Figure 2, in the drawing apparatus 100, the punch 11, the wrinkle holder 12, and the die pressing portion 13 are arranged so that in the first state, a first distance L1 in a first direction DR1 between the first end 11A of the punch 11 and the blank BR is longer than a second distance L2 between the tip end 13A1 of the die pressing portion 13 and the second annular surface 22A of the die 20.

[0043] Furthermore, when the punch 11 moves the second distance L2 in the first direction DR1 from the first state toward the bottom dead center, the die pressing part 13, the second spring 15, and the outer shell member 16 move the second distance L2 in the first direction DR1 together with the punch 11, and the tip end 13A1 of the die pressing part 13 contacts the second annular surface 22A of the die 20, and the second state shown in Figures 3 and 4 is realized. In the second state, the first end 11A of the punch 11 does not contact the blank BR. The distance between the first end 11A of the punch 11 and the blank BR in the second state is the difference (L1-L2) between the first distance L1 and the second distance L2. During the above movement, the blank pressing part 12, the fifth end 14A of the first spring 14, the first annular member 17, and the second annular member 18 do not move in the first direction DR1. During the period from when the first state is realized until when the second state is realized, the first spring 14 is compressed compared to the first state, whereas during the period from when the first state is realized until when the second state is realized, the second spring 15 is not compressed compared to the first state.

[0044] As described above, in the drawing apparatus 100, the wrinkle suppressor 12, the die pressing part 13, the first spring 14, the first annular member 17, and the second annular member 18 are provided so that the load applied to the first spring 14 in the second state is an appropriate wrinkle suppressor load for suppressing the formation of wrinkles in the forming material DP. For example, based on the appropriate wrinkle suppressor load and the spring rate of the first spring 14, the initial length and deflection of the first spring 14 required to generate an appropriate wrinkle suppressor load are estimated. Furthermore, based on the estimated initial length and deflection of the first spring 14, the dimensions of the wrinkle suppressor 12, the die pressing part 13, the first annular member 17, and the second annular member 18 required to appropriately position the first spring 14 are estimated.

[0045] As described above, in the drawing apparatus 100, an initial load is applied to the second spring 15. Therefore, the second spring 15 is not compressed until a load exceeding the initial load is applied. Furthermore, the initial load of the second spring 15 is greater than the load applied to the first spring 14 in the second state and the third state in which the die pressing portion 13 contacts the second annular surface 22A. Therefore, the second spring 15 is not compressed until the second state is reached in which an appropriate wrinkle-preventing load capable of suppressing the occurrence of wrinkles in the forming material DP is applied to the first spring 14. As a result, in the drawing apparatus 100, the deflection amount of the second spring 15 with respect to the first state does not become greater than the difference (L1-L2) before the second state is reached, so that the first end 11A of the punch 11 is prevented from reaching the blank BR and starting the drawing process.

[0046] After the second state is realized, the punch 11 moves further in the first direction DR1 toward the bottom dead center. At this time, only the punch 11 moves in the first direction DR1 a distance longer than the difference (L1-L2). The die pressing portion 13 and the seventh end 15A of the second spring 15 do not move in the first direction DR1. As a result, the punch 11 reaches the bottom dead center, the third state shown in Figs. 5 and 6 is realized, the blank BR is deep drawn, and the forming material DP is formed. After the second state is realized and before the third state is realized, the second spring 15 is compressed compared to the second state. On the other hand, after the second state is realized and before the third state is realized, the first spring 14 is not compressed compared to the second state. Therefore, from the second state to the third state, the load applied by the first spring 14 to the blank holder 12, i.e., the load applied to the first spring 14, is kept constant. In other words, the load that the first spring 14 continues to apply to the wrinkle suppression portion 12 from the second state until the third state is realized becomes the maximum load that the first spring 14 applies to the wrinkle suppression portion 12 during one stroke in which the punch 11 moves from the top dead center to the bottom dead center.

[0047] As described above, the load that the first spring 14 continues to apply to the blank holder 12 from the second state until the third state is achieved is set to an appropriate blank holder load that can suppress the occurrence of wrinkles in the formed material DP after deep drawing. Therefore, in the drawing apparatus 100, deep drawing can be performed in a state in which an appropriate blank holder load is continuously applied to the outer periphery of the blank BR. As a result, the drawing apparatus 100 can suppress the occurrence of wrinkles and tears in the formed material DP even when used in deep drawing.

[0048] In the drawing apparatus 100, the second spring 15 is provided so that the load applied to the second spring 15 when the third state is realized does not exceed the withstand load of the second spring 15.

[0049] <Effects> Although some of the description will overlap with the above description, the characteristic configuration and effects of the drawing apparatus 100 according to this embodiment will be summarized below.

[0050] Since the drawing apparatus 100 includes a first spring 14 sandwiched between the wrinkle holder 12 and the intermediate portion 13B of the die pressing portion 13, and a second spring 15 sandwiched between the intermediate portion 13B and the second end portion 11B of the punch 11, the load applied to the punch 11 to lower the punch 11 to the bottom dead center after the wrinkle holder 12 applies a load sufficient to suppress the occurrence of wrinkles to the outer periphery of the blank BR is not applied to the blank BR via the wrinkle holder 12. Therefore, according to the drawing apparatus 100, the occurrence of wrinkles and tearing in the forming material DP can be suppressed even when deep drawing is performed.

[0051] In the drawing apparatus 100, the initial load of the second spring 15 is greater than the load applied to the first spring 14 in the second and third states in which the die pressing portion 13 is in contact with the second annular surface 22A. Therefore, the second spring 15 does not compress until an appropriate wrinkle-preventing load capable of suppressing the occurrence of wrinkles in the forming material DP is applied to the first spring 14. As a result, in the drawing apparatus 100, the drawing process is not started before an appropriate wrinkle-preventing load is applied to the blank BR.

[0052] The initial load of the second spring 15 may be equal to the load applied to the first spring 14 in the second and third states in which the die pressing portion 13 is in contact with the second annular surface 22A. In other words, the initial load of the second spring 15 only needs to be equal to or greater than the load applied to the first spring 14 in the second and third states in which the die pressing portion 13 is in contact with the second annular surface 22A. Even in this case, the second spring 15 does not compress until an appropriate wrinkle suppression load capable of suppressing the occurrence of wrinkles in the molding material DP is applied to the first spring 14.

[0053] As described above, the first spring 14 is provided to apply an appropriate blank pressing load to the blank BR via the blank pressing portion 12 from the second state to the third state, and from the third state to the third state. The second spring 15 is provided to start compression after the appropriate blank pressing load is applied to the blank BR by the first spring 14, and to have a load capacity higher than the load applied when the punch 11 reaches the bottom dead center. In the drawing apparatus 100, the spring rate of the second spring 15 is different from the spring rate of the first spring 14. In this way, the degree of freedom in design is increased compared to when the spring rate of the second spring 15 is equal to the spring rate of the first spring 14, and each of the first spring 14 and the second spring 15 can be easily designed.

[0054] Preferably, the spring rate of the second spring 15 is lower than that of the first spring 14. In this way, each of the first spring 14 and the second spring 15 can be configured with a general spring that is set so that the spring rate decreases as the amount of deflection increases. On the other hand, if the first spring 14 configured with a general spring applies an excessive load to the blank BR in the second state, the spring rate of the first spring 14 may be set lower than that of a general spring. In this case, the spring rate of the first spring 14 may be higher than that of the second spring 15 or may be lower than that of the second spring 15.

[0055] In the drawing apparatus 100, after the first state is realized, the die pressing portion 13 and the second spring 15 move in the first direction DR1 together with the punch, and only the first spring 14 is compressed, until the second state in which the die pressing portion 13 contacts the second annular surface 22A is realized. After the second state, only the punch 11 moves in the first direction DR1, and the second spring 15 is compressed, until the third state in which the punch 11 reaches the bottom dead center is realized. The deflection amount of the first spring 14 in the third state is equal to the deflection amount of the first spring 14 in the second state. That is, in the drawing apparatus 100, the load applied to the first spring 14 is constant until the state transitions from the second state to the third state. Therefore, it is possible to suppress the application of a large load to the first spring 14 that would cause tearing in the forming material DP.

[0056] In order to apply an appropriate load to each of the first spring 14 and the second spring 15, the positional relationship of each of the first spring 14 and the second spring 15 with respect to the punch 11 needs to be appropriately set. In the drawing apparatus 100, since each of the first spring 14 and the second spring 15 is arranged coaxially with the punch 11, it is easier to manage the load applied to each of the first spring 14 and the second spring 15 compared to a case in which each of the first spring 14 and the second spring 15 is not arranged coaxially with the punch 11. In addition, since the punch 11 is passed through the inside of each of the first spring 14 and the second spring 15, the punch section 10 can be made smaller in size in the radial direction compared to a case in which the punch 11 is arranged outside each of the first spring 14 and the second spring 15.

[0057] In the drawing apparatus 100, the punch unit 10 includes a first annular member 17 disposed between the wrinkle holder 12 and the first spring 14 in the first direction DR1, and a second annular member 18 (second adjustment member) disposed between the wrinkle holder 12 and the die pressing unit 13 in the first direction DR1. As described above, each of the first annular member 17 and the second annular member 18 can adjust the amount of deflection of the first spring 14 in the first direction DR1. In the drawing apparatus 100, the adjustment range of the amount of deflection of the first spring 14 in the first direction DR1 is wider than in a case where the first annular member 17 and the second annular member 18 are not provided.

[0058] In the drawing apparatus 100, the second annular surface 22A of the die 20 is disposed closer to the second end 11B of the punch 11 in the first direction DR1 than the first annular surface 21B. Therefore, it is easier to design the punch 11, the blank holder 12, and the die pressing unit 13 so that the first distance L1 is longer than the second distance L2 in the first state, compared to a case in which the second annular surface 22A is disposed on the same plane as the first annular surface 21B.

[0059] <Modification> The punch unit 10 of the drawing apparatus 100 according to this embodiment may be modified as follows. The punch unit 10 of the drawing apparatus 100 may include at least one first spring 14 and at least one second spring 15. The punch unit 10 may include one first spring 14 and multiple second springs 15. The punch unit 10 may include multiple first springs 14 and one second spring 15. The punch unit 10 may include multiple first springs 14 and multiple second springs 15.

[0060] As shown in FIG. 7, the punch unit 10 may include a plurality of second springs 15. The plurality of second springs 15 have the same configuration. In this case, a plurality of storage sections 13E are formed in the middle section 13B of the die pressing section 13. Each of the plurality of second springs 15 is stored in one storage section 13E. Preferably, each of the plurality of second springs 15 has rotational symmetry with respect to the central axis of the punch 11. In this case, each of the plurality of storage sections 13E also has rotational symmetry with respect to the central axis of the punch 11. The two second springs 15 shown in FIG. 7 have 180-degree rotational symmetry around the central axis of the punch 11. The punch unit 10 may include three or more second springs 15.

[0061] As shown in FIG. 8, the punch section 10 may include a plurality of first springs 14. The plurality of first springs 14 have the same configuration. In this case, at least one accommodation section 13E is formed in the middle section 13B of the die pressing section 13. The die pressing section 13 further includes a movable section 13F that is in contact with the fourth end section 12B of the blank holder 12 and is relatively movable in the first direction DR1 together with the blank holder 12 with respect to the punch 11 and the middle section 13B. The movable section 13F has a plurality of positioning sections 13F for positioning each of the plurality of first springs 14. Each of the plurality of positioning sections 13F is provided as a protruding section that protrudes from the cylindrical section 13A side toward the second end section 11B side of the punch 11 in the first direction DR1, for example. Preferably, each of the plurality of first springs 14 has rotational symmetry with respect to the central axis of the punch 11. In this case, each of the plurality of positioning sections 13F also has rotational symmetry with respect to the central axis of the punch 11. 8 have 180-degree rotational symmetry about the central axis of the punch 11. The punch unit 10 may include three or more first springs 14.

[0062] The punch unit 10 shown in Fig. 8 may include two second springs 15, similar to the punch unit 10 shown in Fig. 7. In this case, the two first springs 14 and the two second springs 15 may be positioned with respect to the punch 11 so that a virtual line connecting the central axes of the two first springs 14 is perpendicular to a virtual line connecting the central axes of the two second springs 15 on the central axis of the punch 11.

[0063] Although the embodiment of the present disclosure has been described above, the above-mentioned embodiment can be modified in various ways. The scope of the present disclosure is not limited to the above-mentioned embodiment. The scope of the present disclosure is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0064] 10 punch portion, 11 punch, 11A first end portion, 11B second end portion, 11C first flange portion, 12 blank holder portion, 12A third end portion, 12B fourth end portion, 12C second flange portion, 13 die pressing portion, 13A1 tip portion, 13A cylindrical portion, 13B middle portion, 13C third flange portion, 13D fourth flange portion, 13E storage portion, 13F positioning portion, 14 first spring, 14A fifth end portion, 14B sixth end portion, 15 second spring, 15A seventh end portion, 15B eighth end portion, 16 outer casing member, 16A first outer casing member, 16B second outer casing member, 16C third outer casing member, 16D fifth flange portion, 17 first annular member, 18 second annular member, 19 holding portion, 20 die, 21 first member, 21A Recess, 21B first annular surface, 22 second member, 22A second annular surface, 100 drawing device.

Claims

1. A drawing apparatus for drawing a plate-shaped workpiece, a punch unit including a punch that moves in a first direction; a die including a recess into which one end of the punch in the first direction is inserted, a first annular surface connected to an outer circumferential edge of the recess, and a second annular surface disposed so as to surround the first annular surface, The punch unit is A blank holder capable of pressing an outer periphery of the workpiece against the first annular surface of the die; a die pressing portion having an intermediate portion disposed between the blank holder and the other end portion of the punch in the first direction and capable of contacting the second annular surface; At least one first spring that is expandable and contractible in the first direction and is sandwiched between the wrinkle holder and the intermediate portion in the first direction; the drawing apparatus further including at least one second spring that is extendable and contractible in the first direction and that is sandwiched between the intermediate portion and the other end of the punch in the first direction.

2. The drawing apparatus according to claim 1 , wherein an initial load of the at least one second spring is equal to or greater than a load applied to the at least one first spring when the die pressing portion is in contact with the second annular surface.

3. 3. The drawing apparatus of claim 1 or 2, wherein a spring rate of the at least one second spring is different from a spring rate of the at least one first spring.

4. After the punch starts to move in the first direction from the top dead center toward the bottom dead center, the blank holder, the die pressing unit, the at least one first spring, and the at least one second spring move in the first direction together with the punch until a first state in which the blank holder presses the outer periphery of the work against the first annular surface of the die is realized; After the first state, until a second state in which the die pressing portion contacts the second annular surface is realized, the die pressing portion and the at least one second spring move in the first direction together with the punch, and only the at least one first spring is compressed; After the second state, until a third state in which the punch reaches the bottom dead center is realized, only the punch moves in the first direction and the at least one second spring is compressed; The drawing apparatus according to claim 1 or 2, wherein a deflection amount of the at least one first spring in the third state is equal to a deflection amount of the at least one first spring in the second state.

5. The drawing apparatus according to claim 1 or 2, wherein each of the at least one first spring and the at least one second spring is arranged coaxially with the punch.

6. The drawing apparatus according to claim 1 or 2, wherein the at least one first spring is a plurality of first springs.

7. The drawing apparatus according to claim 1 or 2, wherein the at least one second spring is a plurality of second springs.

8. At least one of a first adjustment member disposed between the wrinkle holder and the at least one first spring in the first direction and a second adjustment member disposed between the wrinkle holder and the die pressing part in the first direction, The drawing apparatus according to claim 1 or 2, wherein each of the first adjustment member and the second adjustment member is capable of adjusting an amount of deflection of the at least one first spring in the first direction.

9. The drawing apparatus according to claim 1 or 2, wherein the second annular surface of the die is disposed closer to the other end of the punch in the first direction than the first annular surface.

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