Press die
The press die design addresses the issue of inconsistent punch insertion in conventional molds by using an upper mold with an elastic member and a stripper plate, ensuring accurate machining despite variations in dead center positions and thermal changes.
Patent Information
- Application Number
- JP2023171984
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-10-03
- Publication Date
- 2025-04-15
AI Technical Summary
Conventional press-machining molds experience variations in the position of the top and bottom dead centers of the slide and punch due to inertia and thermal expansion/contraction, leading to inconsistent punch insertion and reduced machining accuracy.
A press die design that includes a lower mold with a die hole, an upper mold with a punch and an elastic member, a stripper plate, and a connecting member allowing relative vertical displacement between the upper mold and the stripper plate, ensuring consistent punch insertion regardless of the dead center positions.
The design maintains consistent punch insertion into the die hole, improving the accuracy of workpiece machining during processes like doweling, by compensating for variations in the dead center positions and thermal changes.
Smart Images
Figure 2025062757000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a press die. [Background technology]
[0002] Patent Document 1 describes a die for press working. The die described in Patent Document 1 includes a bolster, a lower die attached to the upper surface of the bolster, a slide provided above the bolster and the lower die so as to be movable in the vertical direction, and an upper die attached to the lower surface of the slide. The lower die is provided with a cylindrical die. The upper die is provided with a cylindrical punch that can advance and retreat into a hole in the die. The die is configured to perform press working such as drawing on a workpiece by cooperation between the die and the punch. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2018-39038 A Summary of the Invention [Problem to be solved by the invention]
[0004] Incidentally, in conventional press dies including that of Patent Document 1, when the slide is moved vertically at high speed, the top and bottom dead points of the slide may vary due to inertia, which may cause the top and bottom dead points of the punch to vary. In addition, the relative positions of the punch of the upper die and the die hole of the lower die at the bottom dead point may change due to thermal expansion caused by a temperature rise in the slide or bolster, or thermal contraction caused by a temperature drop. For this reason, the amount of penetration of the punch into the die, i.e., the amount of pressing of the punch into the workpiece, may vary, which may deteriorate the machining accuracy of the workpiece. [Means for solving the problem]
[0005] A press die for solving the above-mentioned problems is a press die for pressing a workpiece, and includes a lower die having a die hole, an upper die provided so as to be movable up and down relative to the lower die, a stripper plate provided between the lower die and the upper die and configured to clamp the workpiece between the lower die and the upper die, and a connecting member connecting the upper die and the stripper plate so as to be relatively displaceable in the up and down direction, the upper die includes a punch and an upper die body that houses an upper end portion of the punch, and the punch includes a first contact member that restricts entry of the punch into the workpiece by contacting the stripper plate. The upper die body has an expanded diameter portion and a second expanded diameter portion located above the first expanded diameter portion and expanded in diameter more than the first expanded diameter portion, and the upper die body is provided with a regulating portion that abuts against the second expanded diameter portion to regulate downward movement of the punch, and an elastic member is provided between the upper end of the punch and a portion of the upper die body located above the upper end, and the elastic member is configured to bias the punch toward the regulating portion and, when the first expanded diameter portion abuts against the stripper plate, to compressively deform itself to allow the upper die body to approach the punch.
[0006] According to this configuration, the stripper plate is connected to the upper die via a connecting member. The upper end of the punch is housed in the upper die body. In addition, an elastic member is provided between the upper end of the punch and a portion of the upper die body located above the upper end. Therefore, as the upper die descends, the stripper plate approaches the workpiece, and the workpiece is sandwiched between the stripper plate and the lower die. Then, as the upper die descends, the tip of the punch enters the die hole while pressing the workpiece until the first enlarged diameter portion of the punch abuts against the stripper plate. Here, since the upper die and the stripper plate are connected by the connecting member so as to be relatively displaceable in the vertical direction, further approach of the upper die to the lower die is permitted. In addition, since the punch is biased toward the regulating portion by the elastic member, the punch is less likely to be pushed back by the workpiece when the punch enters the workpiece. As a result, the workpiece is pressed by the punch.
[0007] Here, even if the bottom dead point of the upper die is at the uppermost position within the range of variation, if the upper die is positioned so that the first enlarged diameter portion of the punch abuts against the stripper plate, the punch can be inserted a constant amount into the die hole. Also, if the bottom dead point of the upper die is lower than the uppermost position within the range of variation, the lower the position, the more the elastic member is compressed and deformed, allowing the upper die body to approach the punch. Therefore, even in these cases, the punch can be inserted a constant amount into the die hole. As a result, the amount of insertion of the punch into the die hole is constant regardless of the position of the bottom dead point of the upper die.
[0008] Therefore, the machining accuracy of the workpiece when performing doweling or the like can be improved. [Brief description of the drawings]
[0009] [Figure 1] FIG. 1 is a perspective view of a stator core. [Diagram 2] FIG. 2 is a cross-sectional view of the stator core taken around the dowel in FIG. [Diagram 3] FIG. 3 is a cross-sectional view showing a press die according to one embodiment, in which an upper die is positioned at the top dead center. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which a workpiece is clamped between the stripper plate and the lower die. [Diagram 5] FIG. 5 is a cross-sectional view showing a state in which the workpiece is being pressed by the punch. [Figure 6] FIG. 6 is a cross-sectional view showing a state in which the first enlarged diameter portion abuts against the stripper plate. [Figure 7] FIG. 7 is a cross-sectional view showing a state in which the upper die is located at the bottom dead center. [Figure 8] FIG. 8 is a cross-sectional view showing a state in which the upper die is located at the bottom dead center, which is located higher than the bottom dead center in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] An embodiment of a press die will be described below with reference to Fig. 1 to Fig. 8. In this embodiment, a press die (hereinafter, press die 20) applied to a manufacturing device for a stator core constituting a motor will be described.
[0011] <Stator core 10> First, a stator core 10 of the present embodiment will be described with reference to FIGS. In addition, in each drawing, for the convenience of explanation, some parts of the configuration may be shown exaggerated or simplified.
[0012] 1, the stator core 10 is substantially cylindrical and has a central hole 10a. The stator core 10 is formed of a laminate in which a plurality of core pieces 15 made of electromagnetic steel sheets are laminated in the axial direction of the stator core 10.
[0013] In the following description, the axial direction of stator core 10 is referred to as the lamination direction, the radial direction of stator core 10 is referred to simply as the radial direction, and the circumferential direction of stator core 10 is referred to simply as the circumferential direction. The stator core 10 includes an annular yoke 11 and a plurality of teeth 12 extending radially inward from the yoke 11 and formed at intervals from one another in the circumferential direction.
[0014] Between the teeth 12 adjacent to each other in the circumferential direction, a slot 13 is formed which opens radially inward and extends radially. As shown in Fig. 2, the multiple core pieces 15 are provided with dowels 16 that bulge out from one side (the lower side in Fig. 2) in the stacking direction of the core pieces 15. The dowels 16 are provided at intervals from each other in the circumferential direction of the core pieces 15.
[0015] The core pieces 15 adjacent to each other in the lamination direction are joined together by crimping the convex and concave portions of the dowels 16 together. <Press mold 20> Next, the press die 20 will be described.
[0016] The press die 20 forms the dowel 16 in the workpiece W by performing press working on the workpiece W. As shown in FIG. 3, the press die 20 includes a fixed base 90, a lower die 21, a movable base 91, an upper die 31, a stripper plate 70, and a connecting member 75.
[0017] The movable base 91 is disposed above the fixed base 90, and is configured to be movable up and down by a driving force applied from a driving device (not shown). (Lower mold 21) The lower mold 21 includes a lower die set 22, a die 23 fixed to the upper surface of the lower die set 22, and a plurality of lower end blocks 29 fixed to the upper surface of the lower die set 22 so as to sandwich the die 23 therebetween.
[0018] The lower die set 22 is fixed to the upper surface of the fixed base 90 . The die 23 has an upper surface 23a and a die hole 24 that opens to the upper surface 23a. (upper mold 31) The upper die 31 includes an upper die body 32 located above the lower die 21 , as well as a punch 50 and an elastic member 62 housed in the upper die body 32 .
[0019] (Upper body 32) The upper die body 32 includes an upper die set 33 and a plate-shaped restricting member 45 fixed to the lower surface of the upper die set 33. The upper die body 32 also includes a plurality of upper end blocks 39 fixed to the lower surface of the upper die set 33 so as to sandwich the restricting member 45 therebetween.
[0020] The upper die set 33 is fixed to the lower surface of the movable base 91. The upper die set 33 is provided so as to be movable up and down relative to the lower die 21 via the movable base 91. The upper die set 33 is provided with a female threaded hole 34 that penetrates in the vertical direction, a accommodating hole 41 with a circular cross section that communicates with the female threaded hole 34 in the vertical direction, and a plurality of through holes 42 that penetrate the upper die set 33 in the vertical direction.
[0021] The inner diameter of the receiving hole 41 is larger than the inner diameter of the female threaded hole 34 . The multiple through holes 42 are arranged so as to sandwich the receiving hole 41 therebetween. The restricting member 45 is provided with a through hole 46 that penetrates in the vertical direction and communicates with the receiving hole 41 .
[0022] The inner diameter of the through hole 46 is smaller than the inner diameter of the accommodation hole 41. A portion of the restriction member 45 that protrudes further inward than the inner circumferential surface of the accommodation hole 41 forms a restriction portion 47. The restricting member 45 is provided with a plurality of first holes 48 penetrating in the vertical direction and arranged to sandwich the through hole 46, and a second hole 49 penetrating in the vertical direction and communicating with the through hole 42.
[0023] The first hole 48 is provided between the through hole 46 and the second hole 49 . The inner diameter of the second hole 49 is smaller than the inner diameter of the through hole 42 . The upper end blocks 39 are opposed in the up-down direction to the lower end blocks 29, respectively. The lower ends of the upper end blocks 39 come into contact with the upper ends of the lower end blocks 29, thereby restricting the upper die 31 from moving downward.
[0024] (Stripper plate 70, connecting member 75) The stripper plate 70 is provided between the lower die 21 and the upper die 31 , and holds the workpiece W between itself and the upper surface 23 a of the lower die 21 .
[0025] The stripper plate 70 is provided with an insertion hole 71 that penetrates in the vertical direction and through which the punch 50, which will be described in detail later, is inserted, and a plurality of female threaded holes 72 that open into the upper surface of the stripper plate 70.
[0026] The connecting member 75 connects the upper die 31 and the stripper plate 70 so as to be capable of relative displacement in the vertical direction. The connecting member 75 includes an elastic member 76 and a stripper bolt 80 .
[0027] An upper end of the elastic member 76 is inserted into the first hole 48 and is connected to the lower surface of the upper die set 33. A lower end of the elastic member 76 is connected to the upper surface of the stripper plate 70. The elastic member 76 in this embodiment is a coil spring.
[0028] The stripper bolt 80 has a cylindrical spacer 81 having a flange 82 at its upper end, and a bolt 83 that is inserted into the spacer 81 from above. The spacer 81 is slidably inserted from above into the second hole 49. The lower end of the spacer 81 abuts against the upper surface of the stripper plate .
[0029] The flange 82 is located inside the through hole 42 and is provided so as to be movable up and down relative to the through hole 42 . The bolt 83 is inserted through the spacer 81 from above and screwed into the female threaded hole 72 .
[0030] (Punch 50) The punch 50 includes a support member 51 , a punch body 56 , a collar 60 , and a receiving member 61 .
[0031] The support member 51 is cylindrical and has at its upper end an expanded diameter portion 52. The outer diameter of the expanded diameter portion 52 is larger than the inner diameter of the through hole 46. The support member 51 is slidably inserted into the through hole 46 from above.
[0032] The punch body 56 has a columnar body portion 57 and a flange portion 58 provided at the upper end of the body portion 57 . The punch body 56 is inserted into the support member 51 from above. The lower surface of the flange portion 58 is in contact with the upper surface of the enlarged diameter portion 52. The lower end of the punch body 56 protrudes downward beyond the lower end portion 53 of the support member 51.
[0033] When the upper die 31 is at the top dead center, the lower end of the punch body 56 is located above the lower surface of the stripper plate 70. A collar 60 is provided on the outer circumferential side of the flange portion 58 inside the receiving hole 41. A receiving member 61 is provided on the upper surfaces of the flange portion 58 and the collar 60.
[0034] (Elastic member 62) An elastic member 62 is provided on the upper surface of the receiving member 61 . The elastic member 62 in this embodiment is a coil spring.
[0035] A screw plug 35 is screwed into the female threaded hole 34 of the upper die set 33. The elastic member 62 is provided in a state in which it is compressed by the lower end surface of the screw plug 35 and the upper end surface of the receiving member 61.
[0036] By adjusting the amount by which the screw plug 35 protrudes into the receiving hole 41, the amount of compression of the elastic member 62, and therefore the magnitude of the biasing force that biases the punch 50 toward the restricting portion 47, can be adjusted.
[0037] In the punch 50 of this embodiment, the lower end portion 53 of the support member 51 has a larger diameter than the main body portion 57 of the punch body 56 . In this embodiment, the lower end portion 53 of the support member 51 abuts against the upper surface of the stripper plate 70, and functions as a first enlarged diameter portion that restricts the entry of the punch 50 into the workpiece W.
[0038] In this embodiment, the expanded diameter portion 52 of the support member 51 abuts against the upper surface of the restricting portion 47 of the restricting member 45, thereby functioning as a second expanded diameter portion that restricts the downward movement of the support member 51. Next, the operation of this embodiment will be described. Note that the fixed base 90 and the movable base 91 are omitted from illustration in Figs.
[0039] As shown in FIG. 3, when the workpiece W is transferred to the upper surface 23a of the die 23, the upper die 31 starts to descend from the top dead center. The stripper plate 70 is connected to the upper die 31 via a connecting member 75. The upper end portion 50a of the punch 50 is housed in the upper die body 32. In addition, an elastic member 62 is provided between the upper end portion 50a of the punch 50 and a portion of the upper die body 32 located above the upper end portion 50a.
[0040] Therefore, as shown in FIG. 4, as the upper die 31 descends, the stripper plate 70 approaches the workpiece W, and the workpiece W is sandwiched between the stripper plate 70 and the lower die 21.
[0041] Then, as shown in Figures 5 and 6 in turn, as the upper die 31 descends, the tip of the punch 50 enters the die hole 24 while pressing the workpiece W until the lower end 53 of the support member 51 abuts against the stripper plate 70.
[0042] Here, the upper die 31 and the stripper plate 70 are connected by a connecting member 75 so as to be capable of relative displacement in the vertical direction. Therefore, as shown in FIGS. 6 and 7 in that order, the elastic member 76 is compressed and the stripper bolt 80 moves upward within the through-hole 42, thereby allowing the upper die 31 to move further closer to the lower die 21.
[0043] Furthermore, since the punch 50 is biased toward the restricting portion 47 by the elastic member 62, the punch 50 is less likely to be pushed back by the workpiece W when the punch 50 enters the workpiece W. In this embodiment, the magnitude of the biasing force with which the elastic member 62 biases the punch 50 is set so that the punch 50 is not pushed back by the workpiece W. As a result, the workpiece W is press-worked by the punch 50.
[0044] 8, the upper die 31 is set so that the lower end 53 of the punch 50 abuts against the stripper plate 70 even if the bottom dead point of the upper die 31 is at the uppermost position within the range of variation. Therefore, the punch 50 can be advanced into the die hole 24 by a constant amount.
[0045] Furthermore, when the bottom dead point of the upper die 31 is lower than the uppermost position within the range of variation, the lower the position, the more the elastic member 62 is compressed and deformed, allowing the upper die body 32 to approach the punch 50. Therefore, regardless of the position of the bottom dead point of the upper die 31, the amount of penetration of the punch 50 into the die hole 24 is constant.
[0046] In this embodiment, the position at which the upper end block 39 abuts against the lower end block 29, restricting the approach of the upper die body 32 to the lower die 21, is the lowest position within the range of variation of the bottom dead center of the upper die 31.
[0047] Next, the effects of this embodiment will be described. (1) The punch 50 has a first enlarged diameter portion that restricts the entry of the punch 50 into the workpiece W by contacting the stripper plate 70, and a second enlarged diameter portion that is located above the first enlarged diameter portion and has a larger diameter than the first enlarged diameter portion. The upper die body 32 is provided with a restricting portion 47 that restricts the downward movement of the punch 50 by contacting the second enlarged diameter portion. The elastic member 62 biases the punch 50 toward the restricting portion 47, and is configured to compressively deform itself when the first enlarged diameter portion is in contact with the stripper plate 70, thereby allowing the upper die body 32 to approach the punch 50.
[0048] According to this configuration, the above-mentioned effect is achieved, thereby improving the machining accuracy of the workpiece W when performing doweling processing, etc. (2) Support member 51 has a first enlarged diameter portion at a lower end and a second enlarged diameter portion at an upper end. Punch body 56 has a main body portion 57 that is inserted into support member 51 and protrudes downward beyond the first enlarged diameter portion, and a flange portion 58 that is provided at the upper end of main body portion 57 and abuts against the upper surface of support member 51.
[0049] Repeated press processing causes the tip of the punch 50, which presses the workpiece W, to wear and become deformed. For this reason, when the tip becomes worn, maintenance measures such as grinding the tip of the punch 50 or replacing the punch 50 with a new one become necessary.
[0050] According to the above configuration, the support member 51 having the first and second enlarged diameter portions and the punch body 56 having the tip portion are separate bodies, so that when the tip portion wears out, it is sufficient to replace only the punch body 56 with a new one. Therefore, compared to when the entire punch 50 is integrally molded, the size of the replacement part can be made smaller, and the cost required for part replacement can be reduced.
[0051] (3) The press die 20 is applied to a manufacturing device for the stator core 10 formed by stacking a plurality of core pieces 15. The press die 20 forms the dowels 16 for each of the core pieces 15 using the punch 50.
[0052] According to this configuration, by forming the dowels 16 in the core pieces 15 using the press die 20, it is possible to reduce the dimensional variation of the dowels 16 formed in each of the core pieces 15. Therefore, when adjacent core pieces 15 are crimped together, the overlapping dowels 16 can be firmly fitted together, so that it is possible to increase the bonding strength between the core pieces 15 and reduce the variation in the bonding strength between the core pieces 15.
[0053] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.
[0054] The support member 51 abuts against the upper surface of the stripper plate 70, and the flange portion 58 of the punch body 56 abuts against the enlarged diameter portion 52 of the support member 51, thereby determining the bottom dead center of the punch body 56. For this reason, the lower end block 29 and the upper end block 39 can be omitted.
[0055] In this embodiment, the connecting member 75 is configured by the elastic member 76 and the stripper bolt 80, but the stripper bolt 80 may be omitted. In this embodiment, the punch 50 is made up of the support member 51 and the punch body 56, but the punch 50 may also be made up of a single part.
[0056] The elastic member 62 is not limited to a coil spring. The elastic member 62 may be made of rubber, for example. In this embodiment, the present invention is embodied as a press die for forming the dowels of the stator core by press working, but the present invention can also be embodied as a press die for forming the dowels of the rotor core. In addition, the press die is not limited to be applied to the motor core manufacturing device, but can be applied to the manufacturing device of other parts. [Explanation of symbols]
[0057] 10…Stator core 10a…Center hole 11…York 12…Teeth 13. Slots 15…Iron core piece 16…Dabo 20... Press mold 21…Lower mold 22…Lower die set 23…Die 23a…Top surface 24…Die hole 29…Lower end block 31...Upper mold 32…Upper body 33…Upper die set 34...Female thread hole 35...Screw plug 39…Upper end block 41...Housing hole 42...Through hole 45...Regulatory components 46…Through hole 47…Regulation Department 48…1st hole 49…Second hole 50...Punch 50a...Top end 51...Support member 52... Expanded diameter part 53...Lower end 56…Punch body 57…Main body 58…Flange section 60…Color 61... Support member 62...Elastic member 70...Stripper plate 71...Through hole 72...Female thread hole 75...Connecting member 76...Elastic member 80...Stripper bolt 81…Spacer 82...Flange 83…Bolt 90…Fixed stand 91…Movable stand
Claims
1. A press die for performing press working on a workpiece, a lower die having a die hole, an upper die provided so as to be movable up and down relative to the lower die, a stripper plate provided between the lower die and the upper die and configured to clamp the workpiece with the lower die, and a connecting member connecting the upper die and the stripper plate so as to be displaceable relative to each other in the up and down direction, The upper mold is Punch and and an upper die body that accommodates an upper end of the punch, the punch has a first enlarged diameter portion that restricts entry of the punch into the workpiece by contacting the stripper plate, and a second enlarged diameter portion that is located above the first enlarged diameter portion and has a larger diameter than the first enlarged diameter portion, a restricting portion that restricts downward movement of the punch by contacting the second enlarged diameter portion is provided on the upper die body, an elastic member is provided between the upper end of the punch and a portion of the upper die body located above the upper end, the elastic member is configured to bias the punch toward the regulating portion, and to allow the upper die body to approach the punch by being compressively deformed when the first enlarged diameter portion is in contact with the stripper plate. Press mold.
2. The punch is a cylindrical support member having the first expanded diameter portion at a lower end and the second expanded diameter portion at an upper end; a punch body including a main body portion that is inserted into the support member and protrudes downward from the first enlarged diameter portion, and a flange portion that is provided at an upper end of the main body portion and abuts against an upper surface of the support member, The press die according to claim 1 .
3. A press die applied to a manufacturing device for a motor core formed by stacking a plurality of iron core pieces, The punch forms a dowel for each of the core pieces, the dowel protruding to one side in the lamination direction of the core pieces and connecting the adjacent core pieces. The press die according to claim 1 or 2.
Citation Information
Patent Citations
Press working metal mould
JP2018039038A
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