Method for molding electromagnetic steel sheet

Abstract

To provide a method for molding an electromagnetic steel sheet with a narrowed bridge width.SOLUTION: A method for molding an electromagnetic steel sheet includes steps of: using a molding device having a thickening punch 11 which has an R shape at an end thereof and collapses a part of a coarse material bridge 20 to form a thickened part, a press bending punch, a collapsing punch, and a finish punch 12 which punches thickened parts 20d, 20e thickened by the thickening punch 11 when finishing a bridge side surface, and collapsing a total of three rows of a left side part 20a, a right side part 20b near both ends and a midship part 20c in a width direction of the coarse material bridge 20, thereby performing raised thickening of two rows; bending the coarse material bridge 20 in a lengthwise direction orthogonal to the width direction; collapsing the thickened parts 20d, 20e to an original thickness in the state where both ends of the coarse material bridge 20 in the lengthwise direction are arrested; and finish punching of the thickened parts 20d, 20e by the finish punch.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a method for forming an electromagnetic steel sheet.

Background Art

[0002] Patent Document 1 discloses a structure of a rotor core in which a bridge pressing portion is formed on a bridge of an electromagnetic steel sheet forming a rotor core, and a protruding portion protruding in the direction opposite to the depression of the bridge pressing portion is formed on an extension line in the longitudinal direction of the bridge. Thereby, when performing a hardening process by pressing on the bridge, the protruding portion absorbs the force that tends to extend in the radial direction of the electromagnetic steel sheet by deforming, and warping of the electromagnetic steel sheet can be suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, since a step between the thickened portion and the crushed portion remains due to the thickening process for work hardening, the pad of the plate presser at the time of finish punching requires a groove-shaped relief shape that avoids interference with the step. However, since the pad requires a width for suppressing the material, if the relief and the pressing width are combined, the width of the pad cannot be narrowed, and the finish width cannot be narrowed. On the other hand, if the thickening width is increased to eliminate the step, the thickening rate becomes low, and the effect of improving the strength cannot be obtained. Therefore, when forming an electromagnetic steel sheet, there is a problem that the width of the bridge cannot be narrowed.

[0005] The present disclosure provides a method for forming an electromagnetic steel sheet that forms an electromagnetic steel sheet with a narrowed bridge width.

Means for Solving the Problems

[0006] The method for forming an electromagnetic steel sheet according to the present disclosure is a method for forming an electromagnetic steel sheet laminated to form a rotor core used in a motor. The electromagnetic steel sheet has an R shape at its end, and includes a bulging punch that crushes a part of a rough bridge to form a bulging portion, a bending punch, a crushing punch, and a finishing punch that punches out the bulging portion that has been bulged by the bulging punch when finishing the side surface of the bridge. The method for forming an electromagnetic steel sheet forms an electromagnetic steel sheet that constitutes a rotor core by lamination. Using the bulging punch, three rows in total are crushed: a left side portion and a right side portion near both ends in the width direction of the rough bridge, and a central portion arranged separately from each of the left side portion and the right side portion between the left side portion and the right side portion, thereby performing two rows of bulging and thickening. A step of bending the rough bridge in the length direction, which is a direction orthogonal to the width direction, using the bending punch; a step of crushing the bulging portion to its original thickness while restraining both ends of the rough bridge in the length direction using the crushing punch; and a finishing step of punching out the bulging portion with the finishing punch are performed. Thereby, when punching for finishing, it is possible to punch a pad arranged on the bulging portion without providing a step.

Effects of the Invention

[0007] According to the present disclosure, it is possible to provide a method for forming an electromagnetic steel sheet in which the width of the bridge is narrowed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Embodiment 1 Hereinafter, the electromagnetic steel sheet forming apparatus 1 according to the present embodiment will be described with reference to the drawings. The forming apparatus 1 includes a bulking punch used in a bulking process for crushing a part of the rough material bridge 20 to form bulking portions 20d and 20e described later, a bending punch used in a process of bending the rough material bridge 20, a crushing punch for crushing the bulking portions 20d and 20e, and a finishing punch used in a finishing process for punching out the bulking portions 20d and 20e when finishing the side surface of the bridge. Here, the electromagnetic steel sheet according to the present embodiment is an electromagnetic steel sheet laminated to form a rotor core of a motor. Here, the lamination direction of the electromagnetic steel sheets is set as the vertical direction.

[0010] FIG. 1 is a top view showing an example of a portion formed by the forming apparatus 1 according to the present embodiment for an electromagnetic steel sheet used as a part of a rotor core.

[0011] Also, FIGS. 2(a) and 2(b) are cross-sectional views when forming the electromagnetic steel sheet shown in FIG. 1. More specifically, FIG. 2(a) shows an example of the arrangement of the bulking punch 11 used in the bulking process, and FIG. 2(b) shows an example of the arrangement of the finishing punch 12, the pad 13, and the die 14 used in the finishing process in the finishing process. Note that both FIGS. 2(a) and 2(b) are cross-sections at the position indicated by II-II in FIG. 1.

[0012] Here, the horizontal direction in FIGS. 2(a) and 2(b) is defined as the width direction of the electromagnetic steel sheet. Here, the width direction is a direction orthogonal to the vertical direction described above. Also, the depth direction in FIGS. 2(a) and 2(b), which is a direction orthogonal to both the vertical direction and the width direction, is defined as the length direction.

[0013] In the rough material bridge 20, a predetermined region near the left end in the width direction is defined as the left side portion 20a, and a predetermined region near the right end is defined as the right side portion 20b and the right end portion. Further, a predetermined region near the center, which is between the left side portion 20a and the right side portion 20b and is spaced apart from each of the left side portion 20a and the right side portion 20b, is defined as the central portion 20c.

[0014] As shown in Fig. 2(a), the bulking punch 11 is a punch arranged to sandwich a plurality of locations on the upper and lower surfaces of the rough material bridge 20 in the forming process of the electromagnetic steel sheet.

[0015] Here, the bulking punch 11 has punches 11a, 11b that sandwich the left side portion 20a in the width direction of the rough material bridge 20 from above and below, punches 11c, 11d that sandwich the right side portion 20b from above and below, and punches 11e, 11f arranged to sandwich the central portion 20c from above and below.

[0016] Here, a first bulking portion 20d is defined between the left side portion 20a and the central portion 20c, and a second bulking portion 20e is defined between the right side portion 20b and the central portion 20c.

[0017] The punches 11a to 11f used as the bulking punch 11 each have an end with an R shape. Thereby, when the punches 11a to 11f press while sandwiching the rough material bridge 20, it is possible to suppress the occurrence of cracks in the rough material bridge 20. In the following, the rough material bridge 20 and those in a state where processing has been advanced on this rough material bridge 20 may be simply referred to as a bridge.

[0018] As shown in Fig. 2(b), among the finishing punches 12, the punch arranged on the left side is the punch 12a, and the punch arranged on the right side is 12b. In the punching process, among the finishing punches 12, the punch 12a is arranged above a predetermined region including the left side portion 20a of the bridge, and the punch 12b is arranged above a predetermined region including the right side portion 20b of the bridge.

[0019] More specifically, the punch 12a can descend from above and press the bridge in a state where it is arranged above the left side portion 20a and a part of the first bulking portion 20d in the rough material bridge 20 shown in Fig. 2(a). Similarly, the punch 12b can descend from above and press the bridge in a state where it is arranged above the right side portion 20b and a part of the second bulking portion 20e.

[0020] Here, the pad 13 and the die 14 are arranged so as to sandwich the central portion 20c, at least a part of the first build-up portion 20d, and at least a part of the second build-up portion 20e in the rough material bridge 20 shown in FIG. 2(a). Typically, the lengths in the width direction of the portions of the first build-up portion 20d and the second build-up portion 20e sandwiched by the pad 13 and the die 14 are longer than the portions of the first build-up portion 20d and the second build-up portion 20e arranged below the punches 12a and 12b.

[0021] Note that the pad 13 has a shape without a step. For example, as shown in FIG. 2(b), it can be rectangular when viewed from the length direction, and also rectangular (not shown) when viewed from the length direction, and the surface in contact with the rough material bridge 20 can also be planar, but it is not limited to this.

[0022] Next, a method for forming an electromagnetic steel sheet according to the present disclosure will be described. FIG. 3 is an example of a flowchart of the method for forming an electromagnetic steel sheet.

[0023] First, the electromagnetic steel sheet forming apparatus 1 performs a build-up process of building up a part of the rough material bridge 20 (step S101).

[0024] Specifically, as shown in FIG. 2(a), the punches 11a and 11b press the left side portion 20a of the rough material bridge 20 from above and below, the punches 11c and 11d press the right side portion 20b of the rough material bridge 20 from above and below, and the punches 11e and 11f press the central portion 20c of the rough material bridge 20 from above and below.

[0025] As a result, in the rough material bridge 20, a first build-up portion 20d that is thick in the vertical direction is formed between the left side portion 20a and the central portion 20c, and a second build-up portion 20e is formed between the right side portion 20b and the central portion 20c. In other words, in the build-up process, the electromagnetic steel sheet forming apparatus 1 can perform two rows of raised build-up by crushing three rows at both ends and the central portion in the width direction.

[0026] Next, the electromagnetic steel sheet forming apparatus 1 performs a bending process of bending the rough material bridge 20 in the longitudinal direction (step S102). Typically, the forming apparatus 1 is provided with a punch for bending the rough material bridge 20 in the longitudinal direction, and the rough material bridge 20 can be bent in the longitudinal direction.

[0027] Next, the electromagnetic steel sheet forming apparatus 1 performs a process of crushing two thickening portions 20d and 20e formed on the bridge (step S103). Specifically, the forming apparatus 1 restrains both ends of the rough material bridge 20 in the longitudinal direction, and crushes the first thickening portion 20d and the second thickening portion 20e from above and below so that the thicknesses of the first thickening portion 20d and the second thickening portion 20e become the original thicknesses.

[0028] Typically, the forming apparatus 1 is provided with punches for sandwiching the rough material bridge 20 from above and below at these positions so that the first thickening portion 20d and the second thickening portion 20e can be crushed in the vertical direction respectively. Thereby, the forming apparatus 1 can crush the first thickening portion 20d and the second thickening portion 20e.

[0029] Next, when finishing the side surface of the bridge, the electromagnetic steel sheet forming apparatus 1 performs a finishing punching process of punching the bridge at two thickening portions (step S104).

[0030] Specifically, as shown in FIG. 2(b), in this process, the pad 13 and the die 14 are arranged so as to sandwich the central portion 20c, which is the portion to be left by punching, the portion of the first thickening portion 20d, and the portion of the second thickening portion 20e from above and below. In this state, in the forming apparatus 1, the punch 12a punches from above to below at the location of the first thickening portion 20d, and the punch 12b punches from above to below at the location of the second thickening portion 20e.

[0031] As a result, in the molding device 1, it is possible to punch out while leaving the necessary parts in the bridge and eliminating the unnecessary parts. That is, in the molding device 1, without widening the widths of the individual build-up portions 20d and 20e, punching is performed at the build-up portions 20d and 20e, so punching can be performed without providing a step on the surface where the pad 13 abuts against the build-up portions 20d and 20e, and the width of the bridge after punching can be narrowed.

[0032] Further, by performing punching according to this procedure, the molding device 1 does not expand the length in the width direction of the build-up portions 20d and 20e. Therefore, by performing molding by the molding method according to the flow shown in FIG. 3, the molding device 1 can increase the build-up rate and improve the strengthening rate for the portions remaining as necessary parts by punching.

[0033] Note that the present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the gist. That is, the above description has been appropriately omitted and simplified for the sake of clarity of explanation, and those skilled in the art can easily change, add, and convert each element of the embodiment within the scope of the present invention.

Explanation of Reference Numerals

[0034] 1 Molding device 11 Build-up punch 12 Finish punching punch 13 Pad 14 Die 20 Rough bridge 20a Left side portion 20b Right side portion 20c Central portion 20d First build-up portion 20e Second build-up portion

Claims

【Claim 1】 A bulking punch having an R shape at its end and forming a bulking portion by crushing a part of the rough material bridge, a bending punch, a crushing punch, and a finishing punch for punching out the bulking portion bulked by the bulking punch when finishing the side surface of the bridge. The method for forming an electromagnetic steel sheet forms an electromagnetic steel sheet that constitutes a rotor core by lamination, a step of performing two rows of raised bulking by crushing a total of three rows including a left side portion, a right side portion near both ends in the width direction of the rough material bridge, and a central portion arranged away from each of the left side portion and the right side portion between the left side portion and the right side portion using the bulking punch, a step of bending the rough material bridge in the length direction, which is a direction orthogonal to the width direction, using the bending punch, a step of crushing the bulking portion to its original thickness while restraining both ends of the rough material bridge in the length direction using the crushing punch, and a finishing step of punching out the bulking portion with the finishing punch. A method for forming an electromagnetic steel sheet.

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