Punching jig and method

Abstract

Provided is a punching jig which enables punching while taking roundness into consideration and which can be easily shaped into a desired form during production, maintenance, or the like of the jig. A punching jig 1 for forming a member 3 having a circular punched part from a steel plate W includes a punch 5 and a die 7 into which the punch 5 enters to enable punching of the member 3. At least one of the outer shape of the punch 5 and the inner shape of the die 7 has a multi-radius shape formed from two or more kinds of convex circular arc portions 9 and 11 with different radii of curvature.

Description

Punching jig and method

[0001] The present invention relates to a punching jig and method for punching a member having a circular punched portion, such as a core piece used in a laminated core of a rotating electrical machine.

[0002] As a conventional punching jig, as disclosed in Patent Document 1, it has been discovered that the roundness of a core piece punched with a circular die is determined by the elongation of the steel sheet, and the roundness of the die is adjusted to make the core piece a perfect circle.

[0003] However, for dies whose roundness is adjusted, it is necessary to adjust the roundness by measuring multiple points during jig production, maintenance, etc. For this reason, conventional punching jigs have the problem that it takes a lot of time and effort to adjust the shape to the desired one during jig production, maintenance, etc.

[0004] This problem occurs when punching a member having a wide circular punched portion.

[0005] Japanese Patent Application Publication No. 10-24333

[0006] The problem to be solved is that it takes time and effort to adjust the shape of the punching jig when punching while taking into consideration the roundness.

[0007] The present invention provides a punching jig for punching out a member having a circular punched portion from a steel plate, the punching jig comprising a punch and a die into which the punch enters to enable punching of the member, and at least one of the outer shape of the punch and the inner shape of the die having a different radius of curvature and having two or more types of regular circular arc portions with different radii of curvature.

[0008] The present invention provides a punching method for punching a member having a circular punched portion from a steel plate, the method comprising: setting circumferential positions of two or more types of regular circular arc portions having different radii of curvature in accordance with the anisotropy of the steel plate on at least one of the outer shape of the punch and the inner shape of the die; and punching the member from the steel plate between the punch and the die by inserting the punch into the die.

[0009] The present invention makes it possible to perform punching taking into consideration roundness and to easily adjust the shape of the punching jig.

[0010] FIG. 1 is a schematic cross-sectional view of a punching jig according to a first embodiment of the present invention. FIG. 2 is a plan view showing an overlapping die and punch of the punching jig in FIG. 1. FIG. 3 is a plan view showing core pieces of a stator core and a rotor core. FIG. 4 is a plan view of a core piece showing an example of anisotropy of a steel sheet. FIG. 5 is a plan view showing an overlapping inner shape of a die and an overlapping outer shape of a punch of a punching jig according to a modified example of the first embodiment. FIG. 6 is a plan view showing an overlapping inner shape of a die and an overlapping outer shape of a punch of a punching jig according to another modified example of the first embodiment. FIG. 7 is a plan view showing an overlapping inner shape of a die and an overlapping outer shape of a punch of a punching jig according to yet another modified example of the first embodiment. FIG. 8 is a plan view showing an overlapping inner shape of a die and an overlapping outer shape of a punch of a punching jig according to yet another modified example of the first embodiment. FIG. 9 is a plan view showing a steel sheet according to yet another modified example of the first embodiment. FIG. 10 is a plan view showing an overlapping inner shape of a die and an overlapping outer shape of a punch of a punching jig according to a second embodiment of the present invention. Fig. 11 is a plan view showing the inner shape of the die and the outer shape of the punch superimposed on each other of a punching jig according to a modified example of Example 2. Fig. 12 is a plan view showing the inner shape of the die and the outer shape of the punch superimposed on each other of a punching jig according to Example 3 of the present invention.

[0011] A punching jig 1 in one embodiment punches out a member 3 having a circular punched portion from a steel sheet W. The punching jig 1 includes a punch 5 and a die 7 into which the punch 5 enters to enable punching out the member 3. At least one of the outer shape of the punch 5 and the inner shape of the die 7 has a different diameter shape having two or more regular circular arc portions 9, 11, 15, 17, 21, and 23 with different radii of curvature.

[0012] The other of the outer shape of the punch 5 and the inner shape of the die 7 can be set arbitrarily depending on the anisotropy of the steel sheet W.

[0013] In one embodiment, one of the outer shape of the punch 5 and the inner shape of the die 7 may have different diameters, and the other of the outer shape of the punch 5 and the inner shape of the die 7 may be a single perfect circle.

[0014] In another embodiment, both the outer diameter of the punch 5 and the inner diameter of the die 7 may be different.

[0015] Two or more kinds of regular circular arc portions 9, 11, 21 and 15, 17, 23 may be arranged concentrically.

[0016] The regular circular arc portions 9 , 11 , 21 and the regular circular arc portions 15 , 17 , 23 that are adjacent in the circumferential direction may be continuous in the circumferential direction via the non-regular circular arc portions 13 and 19 .

[0017] The punching method involves setting circumferential positions of two or more regular circular arc portions 9, 11, 15, 17, 21, and 23 having different radii of curvature according to the anisotropy of the steel sheet W on at least one of the outer shape of the punch 5 and the inner shape of the die 7, and then inserting the punch 5 into the die 7 to punch out the member 3 from the steel sheet W between the punch 5 and the die 7.

[0018] The steel plate W may be set so that the lateral bending direction of the steel plate W is a predetermined direction, and the member 3 may be punched out from the steel plate W.

[0019] [Punching Jig] Fig. 1 is a schematic cross-sectional view of a punching jig according to Example 1 of the present invention. Fig. 2 is a plan view showing a die and a punch of the punching jig overlapped in Fig. 1. Fig. 3 is a plan view showing core pieces of a stator core and a rotor core.

[0020] The punching jig 1 in Fig. 1 punches out core pieces 3 as members having circular punched portions from a steel plate W. The core pieces 3 are used in laminated cores for rotating electrical machines. The laminated cores may be either stator cores or rotor cores. Note that the members having circular punched portions are not limited to the core pieces 3, and may be any members having a circular outer or inner shape.

[0021] In this embodiment, the core piece 3A in Fig. 3(A) is a core piece of a stator core, and is an annular plate material with a circular punched portion in the inner and outer shapes. The core piece 3B in Fig. 3(B) is a core piece of a rotor core, and is an annular plate material with a center hole 6 in the inner and outer shapes.

[0022] 3A and 3B show only the outline shapes of the core pieces 3A and 3B. The circular inner shape of the core piece 3A of the stator core is the shape of an imaginary circle where the tips of the teeth 4 are located. In the following explanation, for convenience of explanation, the core pieces 3A and 3B are collectively referred to as core pieces 3. Furthermore, unless otherwise necessary, the circular inner and outer shapes of the core piece 3A and the circular inner and outer shapes of the core piece 3B are referred to as punched portions.

[0023] The punching jig 1 of this embodiment is used to form core pieces 3 from a steel sheet W, and reduces (improves) the roundness of the punched portion of the core pieces 3. In the case of the outer shape of the core pieces 3, the roundness refers to half the difference between the maximum outer diameter and the minimum outer diameter. Similarly, the roundness of the inner shape of the core pieces 3 refers to half the difference between the maximum inner diameter and the minimum inner diameter.

[0024] The punching jig 1 includes a punch 5 and a die 7. The punch 5 is attached to an upper die or the like, and the die 7 is attached to a lower die or the like. The punch 5 and the die 7 are positioned relatively close to each other, allowing the punch 5 to enter a hole 7a in the die 7 and punch out the core piece 3. Here, punching out the core piece 3 refers to punching out the inner and outer shapes of the core piece 3A and the outer shape of the core piece 3B.

[0025] At least one of the outer shape of the punch 5 and the inner shape of the die 7 has a different diameter, with two or more regular circular arc portions 9 and 11 having different radii of curvature, within the range where the punch 5 enters the hole 7a of the die 7. In this embodiment, the inner shape of the die 7 has a different diameter, with two types of regular circular arc portions 9 and 11. The regular circular arc portions 9 and 11 refer to arc-shaped portions that are parts of a regular circle. In this embodiment, a regular circle refers to a circle having the circularity required for the core piece 3.

[0026] The number, position, diameter, center position, etc. of the perfect circular arc portions are set according to the anisotropy of the steel sheet W. The anisotropy of the steel sheet W refers to the property or directionality of the punched core pieces 3 elongating relative to the perfect circle in a plan view when the core pieces 3 are punched out assuming that the outer shape of the punch 5 and the inner shape of the die 7 are perfect circles. Figure 4 shows an example of anisotropy. In Figure 4, the punched core pieces 3 elongate in the feed direction of the steel sheet W (the left-right direction in Figures 1, 2, and 4).

[0027] Accordingly, in this embodiment, as described above, two types of regular circular arc portions 9 and 11 are provided on the die 7. Specifically, the regular circular arc portions 9 having a relatively small diameter are positioned on both sides of the hole 7a of the die 7 in the feed direction of the steel sheet W, and the regular circular arc portions 11 having a relatively large diameter are positioned on both sides of the hole 7a of the die 7 in the width direction of the steel sheet W perpendicular to the feed direction (the direction perpendicular to the plane of the paper in FIG. 1 , the up-and-down direction in FIGS. 2 and 4 ).

[0028] The two types of regular arc portions 9 and 11 are arranged concentrically, but their centers may be offset. The regular arc portions 9 and 11 adjacent in the circumferential direction are continuous in the circumferential direction via a non-regular arc portion 13. The non-regular arc portion 13 refers to a straight or curved portion that is not part of a regular circle. The non-regular arc portion 13 in this embodiment is a linear portion that runs along the radial direction. It is preferable that the non-regular arc portions 13 are arranged so as to be symmetrical about the center.

[0029] [Punching Method, etc.] In the punching method of this embodiment, first, the circumferential positions of the regular arc portions 9 and 11 on the inner diameter of the die 7 are set in accordance with the anisotropy of the steel sheet W. The anisotropy of the steel sheet W can be confirmed in advance by punching the steel sheet W with the outer shape of the punch 5 and the inner shape of the die 7 set to perfect circles. Then, the regular arc portions 9 and 11 of the die 7 are formed at circumferential positions in accordance with this anisotropy. However, the circumferential positions of the regular arc portions 9 and 11 of the die 7 that have already been formed may be adjusted by rotation, etc.

[0030] With this setting, for example, the regular arc portions 9 and 11 are located on both sides in the feed direction and on both sides in the width direction as shown in Fig. 2. However, depending on the anisotropy of the steel sheet W, the regular arc portions 9 may be located on both sides in a direction inclined relative to the feed direction, rather than in the feed direction. Accordingly, the regular arc portions 11 may also be located on both sides in a direction inclined relative to the width direction, rather than in the width direction.

[0031] With the circular arc portions 9 and 11 set in this manner, the core pieces 3 are punched out from the steel sheet W. That is, the punch 5 descends and enters the die 7, and the punched portions of the core pieces 3 are punched out from the steel sheet W between the die 7 and the punch 5. As described above, the punching of the core pieces 3 is performed for the inner or outer shape in the case of a stator core, and for the inner and outer shapes in the case of a rotor core.

[0032] The punched portion of the core piece 3 punched in this manner has improved roundness due to suppression of uneven elongation. For example, in the punched portion of the core piece 3, elongation is suppressed in the portion where the clearance between the punch 5 and the die 7 is small, improving the roundness of the inner and outer shapes of the core piece 3. Note that although the case where clearance is used has been given as an example of improving roundness, it can also be achieved by suppressing or promoting partial elongation based on the outer shape of the punch 5 and the inner shape of the die 7.

[0033] The outer shape of the punch 5 and the inner shape of the die 7 are each composed of a single perfect circle and perfect circular arc portions 9 and 11 with different diameters, and therefore the shapes are simple and can be easily adjusted to the desired shape by grinding or the like when manufacturing the jig or during maintenance.

[0034] Furthermore, since the punch 5 has a single perfect circle as its outer shape, the structure can be simplified.

[0035] Furthermore, since the regular circular arc portions 9 and 11 are arranged concentrically, it is easier to adjust the shape.

[0036] The regular arc portions 9 and 11 that are adjacent in the circumferential direction are continuous in the circumferential direction via the non-regular arc portion 13, and therefore can be provided only where necessary. As a result, it is possible to omit shaping the non-regular arc portion 13, and it is easier to shaping the regular arc portions 9 and 11.

[0037] Furthermore, in the punching method of this embodiment, the circular arc portions 9 and 11 are positioned circumferentially on the inner surface of the die 7 in accordance with the anisotropy of the steel sheet W, so that the roundness of the punched core pieces 3 can be reliably improved.

[0038] The inner shape of the die 7 and the outer shape of the punch 5 may be reversed, so that the outer shape of the punch 5 has a different diameter and the inner shape of the die 7 is a perfect circle. Also, both the inner shape of the die 7 and the outer shape of the punch 5 may have different diameters.

[0039] [Modification] FIG. 5 is a plan view showing the inner shape of the die and the outer shape of the punch of a punching jig according to a modification of the first embodiment, superimposed on each other.

[0040] In the modification shown in Fig. 5, the inner shape of the die 7 is the same as that of Example 1, and the outer shape of the punch 5 has a different diameter, similar to the inner shape of the die 7. That is, the outer shape of the punch 5 has two types of regular circular arc portions 15 and 17. The regular circular arc portions 15 with relatively small diameters are located on both sides in the feed direction of the steel sheet W, and the regular circular arc portions 17 with relatively large diameters are located on both sides in the width direction of the steel sheet W.

[0041] The regular circular arc portions 15 and 17 of the punch 5 are disposed parallel to the regular circular arc portions 9 and 11 of the die 7, respectively. The regular circular arc portions 15 and 17 of the punch 5 are connected by a linear non-regular circular arc portion 19 that extends in a direction inclined relative to the radial direction.

[0042] In this modified example, by making the outer diameter of the punch 5 as well as the inner diameter of the die 7 different, the roundness of the core piece 3 can be improved more flexibly.

[0043] Fig. 6 is a plan view showing the overlapping inner shape of the die and the outer shape of the punch of a punching jig according to another modification of Example 1. In Fig. 6, non-circular arc portions 13 and 19 are shown by dashed thin lines.

[0044] 6, the clearance between the punch 5 and the die 7 is constant. In this modification, the regular circular arc portions 9 and 11 of the die 7 having different diameters are spaced apart in the circumferential direction, and the non-regular circular arc portion 13 has a curved shape connecting the circumferential ends of the regular circular arc portions 9 and 11.

[0045] Similarly, the regular circular arc portions 15 and 17 of the punch 5 having different diameters are spaced apart in the circumferential direction, and the non-regular circular arc portion 19 is curved to connect the circumferential ends of the regular circular arc portions 15 and 17. Note that the non-regular circular arc portions 13 and 19 may be linear instead of curved.

[0046] 6, it is possible to more easily shape the circular arc portions 9 and 11 and 15 and 17. Note that only one of the inner shape of the die 7 and the outer shape of the punch 5 may be made to have a different diameter, and the other may be made to be a perfect circle.

[0047] Fig. 7 is a plan view showing the overlapping inner shape of the die and the outer shape of the punch of a punching jig according to yet another modification of Example 1. In Fig. 7, non-circular arc portions 13 and 19 are shown by dashed thin lines.

[0048] In the modification of FIG. 7, the positions of the centers of the circular arc portions 9 and 11 of the inner shape of the die 7 are shifted from each other in the modification of FIG. 6, and the positions of the centers of the circular arc portions 15 and 17 of the outer shape of the punch 5 are shifted from each other.

[0049] The center position of the circular arc portion may be shifted in only one of the inner shape of the die 7 and the outer shape of the punch 5, and the circular arc portion may be concentric in the other. Also, only one of the inner shape of the die 7 and the outer shape of the punch 5 may have different diameters, and the other may be a perfect circle.

[0050] In this modified example, by shifting the center positions of the circular arc portions 9 and 11 and the circular arc portions 15 and 17, the roundness of the core pieces 3 can be improved more flexibly.

[0051] FIG. 8 is a plan view showing the inner shape of the die and the outer shape of the punch of a punching jig according to yet another modification of the first embodiment, superimposed on each other.

[0052] 8 differs from the modification of FIG. 6 in that the non-circular arc portions 13 and 19 are formed in an arc shape that faces in the opposite direction to the continuous regular arc portions 9 and 11, and 15 and 17, respectively. In this modification, weld grooves, radial protrusions, key portions, etc. based on the shapes of the non-circular arc portions 13 and 19 can be formed in the punched core piece 3. Alternatively, the non-circular arc portions 13 and 19 can avoid weld grooves, radial protrusions, key portions, etc. that have already been formed. Note that only one of the inner shape of the die 7 and the outer shape of the punch 5 may have a different diameter, and the other may be a perfect circle.

[0053] FIG. 9 is a plan view showing a steel plate according to still another modification of the first embodiment.

[0054] As shown in Fig. 9, the steel sheet W is set in an uncoiler (not shown) in a rolled state and is sequentially fed out for punching. This steel sheet W may develop a so-called lateral bend during the manufacturing process. The lateral bend is a bending of the steel sheet W with one side and the other side in the width direction facing inward and outward, respectively, as indicated by the arrows in Fig. 9.

[0055] Depending on the direction of the lateral bending, this affects the anisotropy of the steel sheet W. For this reason, in this modified example, the steel sheet W is set so that the direction of the lateral bending of the steel sheet W is a predetermined direction, and the core pieces 3 are punched out from the steel sheet W with the lateral bending direction in the predetermined direction, as in the above embodiment.

[0056] As a result, even if the steel plate W is laterally bent, the roundness of the punched portion of the core piece 3 can be reliably improved.

[0057] Fig. 10 is a plan view showing the inner shape of the die and the outer shape of the punch of the punching jig according to Example 2 superimposed on each other. In Fig. 10, non-circular arc portions are indicated by dashed and thin lines. In addition, the basic configuration of Example 2 is similar to that of Example 1, and components that are the same as or correspond to those of Example 1 are indicated by the same reference numerals, and redundant explanations will be omitted.

[0058] In the punching jig 1 of Example 2, the inner shape of the die 7 and the outer shape of the punch 5 are different diameters, and each has three types of regular circular arc portions 9, 21, and 11, and 15, 23, and 17. Note that only one of the inner shape of the die 7 and the outer shape of the punch 5 may be different diameters, and the other may be a regular circle.

[0059] The regular circular arc portions 9, 21, and 11 of the die 7 are set to have relatively large, medium, and small radii of curvature, respectively. The regular circular arc portion 21, which has a medium radius of curvature, is located on both sides in the feed direction of the steel sheet W. On both sides of this regular circular arc portion 21 in the circumferential direction, regular circular arc portions 9 and 11, which have large and small radii of curvature, are located via non-regular circular arc portions 13. The non-regular circular arc portion 13 is curved, but may also be linear.

[0060] The regular circular arc portions 15, 23, and 17 of the punch 5 are arranged in the same manner as the regular circular arc portions 9, 21, and 11 of the die 7. That is, the regular circular arc portion 23 with a medium radius of curvature is located on both sides in the feed direction of the steel sheet W, and the regular circular arc portions 15 and 17 with large and small radii of curvature are located on both sides of the regular circular arc portion 23 in the circumferential direction, with non-regular circular arc portions 19 interposed therebetween. The non-regular circular arc portion 19 is curved, but may also be linear.

[0061] FIG. 11 is a plan view showing the inner shape of the die and the outer shape of the punch of the punching jig according to a modification of the second embodiment, superimposed on each other.

[0062] In the modified example of Fig. 11, only the outer shape of the punch 5 has three types of regular arc portions 15, 23, and 17, and the inner shape of the die 7 is a perfect circle. Of the regular arc portions 15, 23, and 17 of the punch 5, regular arc portions 15 and 17 with relatively large and small radii of curvature are located on both sides in the width direction and both sides in the feed direction, respectively. Between the large and small regular arc portions 15 and 17 in the circumferential direction, regular arc portions 23 with a medium radius of curvature are located via non-regular arc portions 19. The non-regular arc portions 19 are linear along the radial direction.

[0063] In the second embodiment and the modified example, in addition to being able to achieve the same effects as those of the first embodiment, the roundness of the core pieces 3 can be improved more flexibly.

[0064] 12 is a plan view showing the overlapping inner shape of the die and the outer shape of the punch of the punching jig according to Example 3. Note that the basic configuration of Example 3 is similar to that of Example 1, and components that are the same as or correspond to those of Example 1 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0065] The punching jig 1 of Example 3 has the inner shape of the die 7 and the outer shape of the punch 5 each having a different diameter, and is provided with three types of regular circular arc portions 9, 21, and 11, and 15, 23, and 17 that are arranged differently in the circumferential direction. Note that it is sufficient if the inner shape of the die 7 and the outer shape of the punch 5 have two or more types of regular circular arc portions.

[0066] The regular circular arc portions 11, 9, and 21 of the die 7 are arranged in the order of large, small, and medium radii of curvature in the clockwise circumferential direction, and the regular circular arc portions 17, 23, and 15 of the punch 5 are arranged in the order of large, medium, and small radii of curvature in the clockwise circumferential direction.

[0067] In the third embodiment, the same effects as those of the first embodiment can be achieved, and in addition, the roundness of the core pieces 3 can be improved more flexibly.

[0068] 1 punching jig 3 core piece (member) 5 punch 7 die 9, 11, 15, 17, 21, 23 regular circular arc portion 13, 19 non-regular circular arc portion W steel plate

Claims

1. A punching jig for punching out a member having a circular punched portion from a steel plate, comprising a punch and a die into which the punch enters to enable punching of the member, and at least one of the outer shape of the punch and the inner shape of the die has a shape of different diameters, having two or more types of regular circular arc portions with different radii of curvature.

2. The punching jig of claim 1, wherein one of the outer shape of the punch and the inner shape of the die has the different diameters, and the other of the outer shape of the punch and the inner shape of the die is a single perfect circle.

3. The punching jig according to claim 1, wherein both the outer shape of the punch and the inner shape of the die have the different diameters.

4. A punching jig according to any one of claims 1 to 3, wherein the two or more types of regular circular arc portions are arranged concentrically.

5. A punching jig according to any one of claims 1 to 3, wherein adjacent regular circular arc portions in the circumferential direction are continuous in the circumferential direction via a non-regular circular arc portion.

6. A punching method for punching a member having a circular punched portion from a steel plate, comprising: determining circumferential positions of two or more types of regular circular arc portions having different radii of curvature according to the anisotropy of the steel plate on at least one of the outer shape of the punch and the inner shape of the die; and punching the member from the steel plate between the punch and the die by inserting the punch into the die.

7. A punching method according to claim 6, wherein the steel plate is set so that the lateral bending direction of the steel plate is a predetermined direction, and the member is punched out from the steel plate.

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