JP2566150B2 - How to punch the iron core - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for punching iron cores of a rotor (rotor) and a stator (stator) of a motor or the like from a strip-shaped electrical steel sheet using a progressive die. Is.

(Prior Art) For example, when punching out a rotor core R and a stator core S of a stepping motor as shown in FIG. 3 and FIG.
As a conventional general method, the method shown in FIG. 5 is used. A thin strip-shaped electrical steel sheet B, which is an iron core material, is sequentially and intermittently fed in the direction of arrow m along a path in which a progressive die (not shown) is arranged. In the step (I), the pilot hole 1 for regulating the feed interval pitch and the slot hole 2 of the stator core S are punched out. In the step (II), the slot hole 3 of the rotor core R and the shaft hole 4 of the stator core S are punched. In step (III), the outer shape 5 of the rotor core R is punched out. In step (IV), the inner shape 6 of the stator core S having a diameter slightly smaller than the outer shape 5 is punched. In step (V),
The outer shape 7 of the stator core S is punched out.

Outline 5 of the rotor core S punched in the step (III)
And the air gap between the stator and the rotor is formed by the dimensional difference of the inner shape 6 of the stator core R punched in the next step (IV), but the dimensional difference is half the thickness of the electrical steel sheet B. It is a slight amount of about 3 times. For this reason, particularly in an iron core having a small air gap, when the inner shape 6 of the stator iron core S is punched by a punch (upper die), a die (lower die) is usually used.
A large amount of ring-shaped scrap discharged from the inside to the outside floats together with the punch and may be removed twice or the die may be damaged. In the case of iron core punching with a small air gap, it is necessary to improve the dimensional accuracy during die manufacturing and to use a durable material to prevent damage to the die. Will increase the cost of manufacturing.

Conventional means for remedying these drawbacks include:
For example, there is an iron core punching method disclosed in Japanese Patent Publication No. 61-39132, and a die for an electric motor iron core disclosed in Japanese Utility Model Publication No. 59-27944. Further, there is a method of punching the rotor iron core R and the stator iron core by separate progressive die devices.

(Problems to be Solved by the Invention) In the punching method of Japanese Patent Publication No. 61-39132 mentioned above,
Of the slot holes 2 of the stator core S punched in the step (I), only the opening 9 is left unpunched, and the inner shape 6 of the stator core S is punched in the step (IV). When pulling out
The openings 9 of the slot holes 2 are punched simultaneously to prevent the scrap from floating. However,
Even in this method, since the scrap width other than the position of the opening 9 is the same as in the conventional case, it is necessary to improve the dimensional accuracy and use a durable material for the die for punching the iron core having a small air gap.

Further, the die for iron core disclosed in Japanese Utility Model Publication No. 59-27944 is one in which the inner shape 6 of the stator iron core S and the slot hole 2 are punched at the same time. Since the punching force is required, the press machine for driving the punch becomes large in size, and the shape of the punch and the die becomes complicated, so that the die manufacturing cost becomes expensive.

Moreover, in the techniques of the above-mentioned respective publications, the outer dimensions of the rotor core are inevitably punched out smaller than the inner dimensions of the stator core, and even a slight deviation occurs in the concentric state of the two. Since the air gap becomes uneven and the electrical performance deteriorates, and the outer shape of the rotor core after punching is ground and finished to obtain higher performance, the air gap becomes larger than desired, so it can be an effective means. There wasn't.

Further, when the rotor iron core and the stator iron core are punched by separate progressive metal molds, each of the above problems is solved, but two pressing devices including the metal mold are required and the stator iron core is also required. Since the blank obtained by punching out the inner shape of No. 1 cannot be used as a rotor core and is processed as scrap, there is a drawback that it is uneconomical. Therefore, an object of the present invention is to provide a novel iron core punching method capable of improving the above-mentioned various problems.

(Means for Solving the Problems) The gist of the present invention is that, with respect to the strip-shaped electrical steel sheet before punching the outer shape of the rotor core, an annular throttle having a diameter larger than the outer shape to be punched and concentric A portion is provided, and the inside of the throttle portion is punched out in a larger diameter state than the outer shape of the predetermined rotor core by the outer shape of the predetermined rotor core or the finishing allowance,
The narrowed portion is flatly punched and expanded in the axial direction so as to have a diameter smaller than the outer diameter punching diameter of the rotor core, and then the inner core of the stator core is punched. It is a punching method.

(Example) The present invention will be described below based on an example shown in FIG. The strip-shaped electrical steel sheet B is intermittently fed in the direction of the arrow m, the pilot hole 11 is struck in the step (I), and the slot for keeping the feed pitch constant in cooperation with the pilot hole 11 in the step (II). Alternatively, the slotted long holes 12 are punched between the pilot holes 11. In the step (III), a bead-shaped projecting annular drawing portion 13 having an inner diameter d ₁ larger than the diameter d ₂ of the outer shape 15 of the rotor core punched in the subsequent step is formed, and the step ( In IV), a shaft hole 14 concentric with the narrowed portion 13 is punched in the shaft center portion. In the step (V), the outer shape 15 of the rotor core R is punched out concentrically with the narrowed portion with a diameter d ₂ smaller than the inner diameter d ₁ of the narrowed portion 13 and is withdrawn as the rotor core R. In the step (VI), the throttle portion 13 is pressed to return the throttle portion to a flat state, and at this time, the diameter d ₂ is reduced to the reduced diameter hole 16 of the small diameter d ₃ by the throttle portion expanded in the axial direction. Become.

In the step (VII), the slot hole 17 of the stator core S is punched around the reduced diameter hole 16, and in the step (VIII), the inner shape 18 of the stator core S is punched with a diameter d ₄ . In this case, the diameter
The dimensional difference between d ₄ and diameter d ₃ will be extracted as ring-shaped scrap, but the diameter d ₃ of the reduced diameter hole 16 will be the rotor core R.
Since the diameter is smaller than the diameter d ₂ after being withdrawn, the scrap width can be made sufficiently large as compared with the conventional method, and the scrap is prevented from floating together with the punch.
Die damage and the like can be significantly reduced. Further, when punching out the outer shape 15 of the rotor core R in the step (V), it is premised that the rotor core R that has been pulled out is ground and finished to a more accurate inner shape. It is also possible to preliminarily punch into a large diameter in consideration of the grinding allowance by expanding the narrowed portion 13.

In step (IX), the outer shape 19 of the stator core S is punched out, and the stator core S is pulled out.

In the process, for example, other processing steps necessary for the rotor core are added between the process (III) and the process (V), and the stator core is added between the process (VI) and the process (VIII). Other processing steps necessary for the above may be added, but the description thereof is omitted in this embodiment.

Further, the narrowed portion 13 can also have various shapes as shown in FIGS. 2A to 2D, and in any case, it is necessary that wrinkles do not occur when returned to the flat state. Furthermore, for electric motor cores and generator cores other than stepping motors,
It can be applied similarly.

Further, it can be applied not only to a normal progressive die device but also to a so-called laminated die device which automatically carries out the work of sequentially crimping and laminating punched iron cores in a die.

(Effects of the Invention) As is clear from the above-described embodiments, the iron core punching method according to the present invention has the following effects.

After punching out the outer shape of the rotor core, the narrowed part is expanded and the punching hole is reduced in diameter, so when punching out the outer shape of the stator core, it is punched with a blank width larger than the air gap, It is possible to prevent double pulling due to floating, and high mold precision is not required, so the mold can be designed easily and at low cost.

For the same reason as above, when punching the outer shape of the rotor core, it is possible to make the rotor core larger in diameter by the amount corresponding to the finishing allowance in advance and finish it by grinding to finish the rotor core with higher accuracy.

Even if the air gap is extremely small, the rotor core and the stator core can be manufactured with high precision and at low cost by the same progressive die device without using separate progressive die devices.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for punching an iron core according to an embodiment of the present invention, FIG. 2 is a sectional view showing various shapes of a throttle portion in the same method, FIG. 3 is a plan view of a rotor iron core, and FIG. FIG. 5 is a plan view of a stator core, and FIG. 5 is a process drawing showing a conventional core punching method. [Explanation of symbols] 11 …… Pilot hole, 12 …… Long hole 13 …… Throttle section, 14 …… Shaft hole 15 …… Rotor core outer shape 16 …… Reduced hole 17 …… Stator core slot hole 18 …… Internal shape of stator core 19 …… Outer shape of stator core B …… Band-shaped electrical steel sheet, R …… Rotor core S …… Stator core

Claims (1)

(57) [Claims] 1. A punching method for an iron core, in which a rotor core and a stator core of an electric motor or the like are sequentially punched from a strip-shaped electrical steel sheet with the same progressive die device, and the strip-shaped electrical core before punching the outer shape of the rotor core. For steel plate,
An annular throttle portion having a diameter larger than the contour to be punched is provided in a concentric state, and the inside of the throttle portion is larger in diameter than the contour of the predetermined rotor core or the contour of the predetermined rotor core by the finishing allowance. After punching with, the flat portion of the narrowed portion is flattened and stretched in the axial direction so as to have a diameter smaller than the outer diameter of the rotor core, and then the inner shape of the stator core is punched. How to punch the iron core.