Pressing device and laminated core manufacturing method

Abstract

To provide a technology capable of reducing the load on a die when a high-strength soft magnetic foil material is press-punched and suppressing the height of burrs on the punched material. [Solution] A press processing device 10 is provided with a punch 12 and a die 14, and punches out a plate-shaped workpiece 18 transported between them by lowering the punch 12, and collects the punched material 20 as a product. The workpiece 18 is made of a high-strength soft magnetic foil material such as an iron-based amorphous alloy foil, and a shear 40 is attached only to the punch 12 side. This shear 40 is composed of a first edge E1 formed at the tip of the punch 12, a second edge E2 formed on the side of the punch 12, and an inclined surface 12a connecting the first edge E1 and the second edge E2, and the shear angle, which is the angle between the horizontal plane H tangent to the first edge E1 and the inclined surface 12a, is set within the range of 0.23 to 0.68 degrees.

Description

[Technical Field]

[0001] The present invention relates to a press processing apparatus and a method for manufacturing a laminated core, and more particularly to a press processing apparatus for punching high-strength soft magnetic foil material such as iron-based amorphous alloy foil, and a method for manufacturing a laminated core using punched material formed by the apparatus. [Background technology]

[0002] Laminated cores used in high-efficiency motors, etc., are manufactured by laminating a large number of high-strength soft magnetic foil materials that have been press-punched into a specified shape and then bonding them together with adhesives, etc. However, high-strength soft magnetic foil materials have a tensile strength of approximately 2,000 MPa and an elongation of approximately 1%, and are a brittle material. Therefore, a large load is applied to the punch and die during press working, causing significant damage and wear to these tools.

[0003] Adding a shear to a tool is considered an effective measure to extend the life of a press die. In other words, it has been a common practice to add a shear to a punch or die depending on the workpiece to be processed in order to suppress plastic deformation of the material. However, for materials with a wide elastic deformation range, such as high-strength soft magnetic foil materials, application of conventional shear designs does not necessarily produce effective results. In particular, when the foil material (punched material) that has been punched out is used as a product, such as in a laminated core, it is common to add a shear to the die side to prevent deformation of the product and to minimize the height of burrs.

[0004] [Non-Patent Document 1] Effect of various processing conditions on cut surface and tool life in punching of amorphous alloy foil / Plasticity and Processing (Journal of the Japan Society for Technology of Plasticity) Vol. 59 No. 692 (2018-9) / Nobuhiro Koseki, Shohei Okada, Takashi Yamaguchi [Non-patent document 2] Cold Working (I) Shearing / Iron and Steel, Vol. 45, No. 4, 1959 / Yasuo Kasuga Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, the present invention aims to provide a technology that can reduce the load on the mold when press-punching high-strength soft magnetic foil material and can suppress the height of burrs on the punched material. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the press processing device of the present invention is an apparatus that includes a punch and a die, and punches out a plate-shaped workpiece transported between the punch and the die by lowering the punch, and recovers the punched workpiece as a product, wherein the workpiece is made of a high-strength soft magnetic foil material, a shear is attached only to the punch side, the shear is composed of a first edge formed at the tip of the punch, a second edge formed on the side of the punch, and an inclined surface connecting the first edge and the second edge, and the shear angle, which is the angle between the horizontal plane tangent to the first edge and the inclined surface, is set within the range of 0.23 to 0.68 degrees. In addition, the method for manufacturing a laminated core according to the present invention is characterized in that a plurality of workpieces punched out by the press processing device and collected as products are stacked and the workpieces are fixed together.

[0007] It is desirable that a shear height, which is the distance between the second edge and the horizontal plane, be set to be equal to or greater than the thickness of the workpiece. The punch may have a multi-step shape having a flat surface connected to the inclined surface. The high-strength soft magnetic foil material is, for example, an iron-based amorphous alloy foil. [Effects of the Invention]

[0008] In the case of the press processing device according to the present invention, shearing is performed with an optimal shear angle on the punch side, which reduces the load on the die and suppresses the burr height of the punched material, making it possible to produce high-quality laminated cores. Furthermore, since no shear is provided on the die, there is no need to re-grind the shear on the die side during maintenance, which simplifies the maintenance process. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a press working device according to the present invention. [Figure 2] FIG. 10 is a waveform diagram showing vibration acceleration during press working. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the cutting edge of the punch. [Figure 4] 1 is a graph showing the relationship between the shear angle applied to the punch, the maximum acceleration during punching, and the burr height of the punched material. [Figure 5] 1 is an SEM photograph showing the state of the die before processing begins. [Figure 6] 1 is an SEM photograph showing the state of the die after punching 500 times with a punch without a shear. [Figure 7] This is an SEM photograph showing the state of the die after punching 20,000 times with a punch having a shear angle of 0.23 degrees. [Figure 8] 1 shows an SEM photograph and a graph showing the burr height of a punched material punched with a punch having a shear angle of 1.14 degrees. [Figure 9] 1 shows an SEM photograph and a graph showing the burr height of a punched material punched with a punch having a shear angle of 0.68 degrees. [Figure 10] FIG. 10 is an enlarged view of a cutting edge portion of another punch according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. FIG. 1(a) illustrates an outline of a press working device 10 according to this embodiment, which is made up of a punch 12, a die 14, a stripper plate 16, and the like. A workpiece 18 is disposed between the stripper plate 16 and the die 14 .

[0011] The workpiece 18 is a high-strength soft magnetic foil material such as an iron-based amorphous alloy foil, and the plate-shaped workpiece 18 wound in a roll is intermittently fed between the punch 12 and the die 14 by a roller or the like (not shown). However, the workpiece 18 may be any other metal foil having mechanical properties equivalent to those of the iron-based amorphous alloy foil. Furthermore, the workpiece 18 is not limited to a single-layer (single-layer) material, but may be a multi-layer (multi-layer) material.

[0012] When the transfer of the workpiece 18 by rollers or the like is temporarily stopped, a pressing force is applied to the punch 12 from a press machine (not shown), and the punch 12 descends and punches out the workpiece 18 between the punch 12 and the die 14, as shown in Figure 1(b). At this time, the plate pressing force applied to the stripper plate 16 makes it possible to peel the punch 12 off the workpiece 18 while keeping the workpiece 18 flat.

[0013] The punched workpiece (hereinafter referred to as "punched material 20") falls downward through the through-hole 14a of the die 14. After being collected as a product, a predetermined number of the punched material 20 are stacked and fixed to each other by adhesive or the like, and are used as a laminated core. When one punching operation is completed, the punch 12 and the stripper plate 16 rise, and the next processing area of ​​the workpiece 18 is transported between the punch 12 and the die 14 by the rotation of the rollers or the like.

[0014] A vibration acceleration sensor 22 is attached to the side surface of the die 14 and its periphery. This vibration acceleration sensor 22 has the function of detecting vibration acceleration generated by the punching process by the punch 12 and sending the detected acceleration to an information processing device 24 wirelessly or via a wired connection. The information processing device 24 is, for example, a PC equipped with a vibration acceleration analysis program or the like.

[0015] FIG. 2(a) shows the waveform of the vibration acceleration sent from the vibration acceleration sensor 22, and shows that a large waveform 30 is observed each time the punch 12 punches. In the present invention, as shown in FIG. 2(b), the maximum value of each waveform 30 of vibration acceleration observed during punching processing by the punch 12 is defined as the "maximum acceleration." According to Newton's equation of motion (F=m×a), the force F can be reduced by reducing the acceleration a, which in turn leads to a reduction in the load on the mold.

[0016] Figure 3 is an enlarged cross-sectional view of the cutting edge portion of punch 12. The first edge located at the tip of punch 12 is defined as "E1," the second edge located further rearward as "E2," the inclined surface connecting first edge E1 and second edge E2 as 12a, the horizontal distance between first edge E1 and second edge E2 as "sear width W1," the vertical distance between first edge E1 and second edge E2 as "sear height: L," the angle between inclined surface 12a and horizontal plane H as "sear angle θ," and the horizontal width of punch 12 as "punch width W2." That is, the shear 40 of the punch 12 is formed by the first edge E1, the second edge E2, and the inclined surface 12a. In the case of this punch 12, "sear width W1 = punch width W2".

[0017] The present invention aims to reduce the load on the die and reduce burrs on the punched material 20 formed by punching by optimizing the shear angle θ imparted to the punch 12. For this purpose, multiple punches 12 with different shear angles θ were prepared, and experiments were conducted in which punching was performed on the workpiece 18, and the maximum acceleration and the height of the burr formed (hereinafter referred to as "burr height") were measured.

[0018] FIG. 4 is a graph showing the results of this experiment, illustrating the relationship between the maximum acceleration and the burr height when the shear angle θ is changed in the range of 0 to 1.14 degrees. As is clear from the figure, as the shear angle θ increases, the maximum acceleration decreases (= the die load decreases), but on the other hand, there is a tendency for the burr height to increase. Furthermore, it has been shown that when a so-called edge punch with a shear angle θ = 0 is used, the burr height is minimized, but the maximum acceleration value is the highest, and the die load is maximized.

[0019] FIG. 5 is an SEM photograph showing the state of the die 14 before press working, and as a matter of course, no damage has occurred around the through-holes 14a, and clean edges appear. Next, FIG. 6 shows the state of the die 14 after 500 punchings with an edge punch having a shear angle θ=0, and shows that large chips have occurred on the edges of the through-holes 14a.

[0020] In contrast, Figure 7 shows the state of the die 14 after 20,000 punchings using a punch with a shear angle θ = 0.23 degrees. No major chipping occurs, and the edge remains almost as clean as before processing. As a result, it was proven that by providing an appropriate shear 40 on the punch 12 side, the life of the die 14 can be extended by at least 40 times.

[0021] Incidentally, even when a punch with a shear angle θ=0.68 degrees and a punch with a shear angle θ=1.14 degrees were used, it was confirmed that no damage occurred to the die 14 after 20,000 punching operations, as described above. Therefore, from the viewpoint of extending the life of the press die, a punch with a shear angle θ = 1.14 degrees can be said to be suitable, but there were recognized problems from the viewpoint of the quality of the punched material.

[0022] That is, Figure 8(a) is an SEM photograph showing the edge portion of a punched material 20 punched by a punch 12 with a shear angle θ = 1.14 degrees, and Figure 8(b) is a graph showing the measurement results of the burr height of the same punched material 20. As shown in the figure, it can be seen that a relatively large burr 20a having a height of 0.025 mm was formed with the punch having a shear angle θ of 1.14 degrees.

[0023] On the other hand, Figure 9(a) is an SEM photograph showing the edge portion of a punched material 20 punched by a punch 12 with a shear angle θ = 0.68 degrees, and Figure 9(b) is a graph showing the measurement results of the burr height of the same punched material 20. As shown in the figure, the punch with a shear angle θ=0.68 degrees only produces a relatively small burr 20a with a height of 0.011 mm.

[0024] Assuming that the core is formed by stacking multiple punched materials 20, in order to maintain its quality (parallelism between the upper and lower surfaces), the burr height of each punched material must be kept within 0.02 mm. For this reason, a shear angle θ of 1.14 degrees is too large, and it is desirable to set it within the range of 0.023 to 0.68 degrees.

[0025] The relationship between the shear height L, the shear angle θ, and the shear width W1 is expressed by the following trigonometric function, Equation 1. [Formula 1] L=tan θ×W1 Therefore, for example, if the shear width W1 is set to 2 mm, the shear height L will be as follows: (1) When the shear angle θ is 0.023 degrees, the shear height L is 0.008 mm. (2) When the shear angle θ is 0.068 degrees, the shear height L is 0.024 mm. However, with the current level of metal processing technology, the limit for achieving a shear height is 0.1 mm, and it is not realistic to impart an ultra-fine shear height such as 0.008 mm or 0.024 mm to the punch 12 .

[0026] Therefore, assuming that the shear height L is set to 0.1 mm or more, the allowable range of the shear width W1 is as follows: (1) When the shear angle θ is 0.023 degrees, the shear width W1 is 25 mm or more. (2) When the shear angle θ is 0.068 degrees, the shear width W1 is 9 mm or more.

[0027] In this embodiment, the thickness T of the workpiece (high-strength soft magnetic foil material) 18 is assumed to be 0.1 mm, which leads to the relationship "shear height L≧thickness T". Until now, from the perspective of suppressing burr height, it was recognized that the limit for shear height was approximately 50% of the plate thickness of the workpiece to be processed. However, this experiment confirmed that in the case of high-strength soft magnetic foil material, burr height can be suppressed to 0.02 mm or less even if a shear height exceeding 100% of the plate thickness is given to punch 12.

[0028] In the above, the punch 12 having only an inclined surface 12a at the cutting edge portion has been described as an example, but the present invention is not limited to this and can also be applied to a multi-stage punch 12 having an inclined surface 12a and a flat surface 12b at the cutting edge portion, as shown in Figure 10, for example. Even in this case, the punch 12 is required to satisfy the following conditions. (1) Shear angle θ: in the range of 0.023 to 0.68 degrees (2) Shear height L: 0.1 mm or more (3) Shear width W1 when shear angle θ is 0.023 degrees: 25 mm or more (4) Shear width W1: 9 mm or more when shear angle θ is 0.068 degrees Incidentally, in the case of this multi-stage punch 12, "punch width W2 = shear width W1 + flat surface width W3 (distance between the first edge E1 and the third edge E3)". [Explanation of symbols]

[0029] 10 Press processing equipment 12 Punch 12a Inclined surface of punch 12b Flat surface of punch 14 Die 14a Die through hole 16 Stripper plate 18 Processing object 20 punched material 20a Punched material burrs 22 Vibration acceleration sensor 24 Information processing equipment 30 Vibration acceleration waveform 40 Shah E1 First edge of punch E2 Second edge of punch E3 Third Edge of the Punch H horizontal plane L Shear height θ shear angle W1 Shear width W2 punch width W3 Flat surface width

Claims

1. A press processing device that includes a punch and a die, punches out a plate-shaped workpiece transported between the punch and the die by lowering the punch, and collects the punched workpiece as a product, the object to be processed is made of a high-strength soft magnetic foil material, The shear is only applied to the punch side. the shear comprises a first edge formed at the tip of the punch, a second edge formed on the side surface of the punch, and an inclined surface connecting the first edge and the second edge; Furthermore, the punch has a multi-stage shape having a flat surface connected to the inclined surface, A press processing device characterized in that a shear angle, which is the angle between the horizontal plane in contact with the first edge and the inclined surface, is set within a range of 0.23 to 0.68 degrees so that the burr height of the punched workpiece is kept within 0.02 mm.

2. 2. The press working device according to claim 1, wherein a shear height, which is the distance between the second edge and the horizontal plane, is set to be equal to or greater than the thickness of the workpiece.

3. 3. The press working device according to claim 1, wherein the high-strength soft magnetic foil material is an iron-based amorphous alloy foil.

4. 10. A method for manufacturing a laminated core, comprising stacking a plurality of workpieces punched by the press working device according to claim 1 and collected as products, and fixing the workpieces together.

5. A processing method using a press processing device that is equipped with a punch and a die, and that punches out a plate-shaped workpiece that is transported between the punch and the die by lowering the punch, and collects the punched workpiece as a product, the object to be processed is made of a high-strength soft magnetic foil material, The shear is only applied to the punch side. the shear comprises a first edge formed at the tip of the punch, a second edge formed on the side surface of the punch, and an inclined surface connecting the first edge and the second edge; Furthermore, the punch has a multi-stage shape having a flat surface connected to the inclined surface, A press processing method characterized by keeping the burr height of the punched workpiece within 0.02 mm by setting a shear angle, which is the angle between the horizontal plane tangent to the first edge and the inclined surface, within a range of 0.23 to 0.68 degrees.

Images