Press working device, method for manufacturing laminated core, and press working method
The press working apparatus with a punch-side shear angle of 0.23 to 0.68 degrees effectively addresses die load and burr issues in high-strength soft magnetic foil materials, enhancing die longevity and core quality.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- KOMATSU SEIKI KOSAKUSHOKK
- Filing Date
- 2026-01-07
- Publication Date
- 2026-07-16
Smart Images
Figure JP2026000253_16072026_PF_FP_ABST
Abstract
Description
Press Working Device, Method for Manufacturing Laminated Core, and Press Working Method
[0001] The present invention relates to a press working device, a method for manufacturing a laminated core, and a press working method, and more particularly to a press working device and a press working method for punching a high-strength soft magnetic foil material such as an iron-based amorphous alloy foil, and a method for manufacturing a laminated core using a punched material formed by the device.
[0002] A laminated core used in a high-efficiency motor or the like is manufactured by laminating a large number of materials obtained by press punching a high-strength soft magnetic foil material into a predetermined shape and fixing them to each other with an adhesive or the like. However, the high-strength soft magnetic foil material has characteristics such as a tensile strength of about 2,000 MPa and an elongation of about 1%, and is a brittle material. Therefore, a large load is applied to the punch and die in press working, and breakage and wear of these tools become remarkable.
[0003] As an effective measure for extending the life of a press die, imparting shear to the tool is considered. That is, conventionally, in order to suppress plastic deformation of the material, shear has been applied to the punch or die according to the processing target. However, for a material with a wide elastic deformation region such as a high-strength soft magnetic foil material, effective results are not always obtained by applying the conventional shear design. In particular, in the case of using the foil material (punched material) on the punched side, such as a laminated core, as a product, it is common to impart shear to the die side in order to suppress deformation of the product and minimize the height of burrs.
[0004] Influence of Various Processing Conditions on the Cut Surface and Tool Life in Punching of Amorphous Alloy Foil / Plasticity and Processing (Transactions of the Japan Society for Plasticity) Vol. 59, No. 692 (2018-9) / Nobuhiro Furuse, Shohei Okada, Takashi Yamaguchi Cold Working (I) Shearing / Iron and Steel, Vol. 45, No. 4, 1959 / Yasuo Kasuga
[0005] In view of the above, an object of the present invention is to provide a technique capable of reducing the die load when press punching a high-strength soft magnetic foil material and suppressing the height of burrs on the punched material.
[0006] To achieve the above objective, the press working apparatus according to this invention is equipped with a punch and a die, and punches out a plate-shaped workpiece conveyed between the punch and the die by the downward movement of 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 provided only on 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 surface in contact with the first edge and the inclined surface, is set within the range of 0.23 to 0.68 degrees. Furthermore, the method for manufacturing a laminated core according to this invention is characterized by stacking a plurality of workpieces punched out by the above press working apparatus and recovered as products, and fixing the gaps between each workpiece.
[0007] It is desirable that the shear height, which is the distance between the second edge and the horizontal plane, be set to be greater than or equal to the thickness of the workpiece. Furthermore, the punch may have a multi-stage shape with a flat surface connected to the inclined surface. Examples of the high-strength soft magnetic foil material include iron-based amorphous alloy foil.
[0008] In the press working apparatus according to the present invention, since the punch side is fitted with a shear that has an optimal shear angle, the mold load is reduced, the burr height of the punched material can be suppressed, and it becomes possible to produce high-quality laminated cores. Furthermore, since it is not necessary to apply a shear to the die, regrinding of the die side shear is unnecessary during maintenance, and the maintenance process is simplified.
[0009] This is a schematic diagram of the press working apparatus according to the present invention. This is a waveform diagram showing the vibration acceleration during press working. This is an enlarged cross-sectional view of the cutting edge portion of the punch. This 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. This is an SEM image showing the state of the die before the start of processing. This is an SEM image showing the state of the die after punching 500 times with a punch without a shear. This is an SEM image showing the state of the die after punching 20,000 times with a punch that has a shear of 0.23 degrees. This is an SEM image and a graph showing the burr height of the punched material punched with a punch that has a shear of 1.14 degrees. This is an SEM image and a graph showing the burr height of the punched material punched with a punch that has a shear of 0.68 degrees. This is an enlarged view of the cutting edge portion of another punch according to this invention.
[0010] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these embodiments. Figure 1(a) illustrates an overview of a press working apparatus 10 according to this embodiment, and consists of a punch 12, a die 14, a stripper plate 16, etc. A workpiece 18 is placed 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 supplied between the punch 12 and the die 14 by a roller (not shown). However, other metal foils having mechanical properties equivalent to those of the iron-based amorphous alloy foil can also be used as the workpiece 18. Furthermore, the workpiece 18 is not limited to a single layer, but may consist of multiple layers.
[0012] When the transfer of the workpiece 18 by rollers or the like is temporarily stopped, a pressing force from a press machine (not shown) is applied to the punch 12, causing the punch 12 to descend and punch out the workpiece 18 between itself and the die 14, as shown in Figure 1(b). At this time, the plate-holding force applied to the stripper plate 16 makes it possible to separate the punch 12 from the workpiece 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 recovered as a product, a predetermined number of these punched materials 20 are stacked and fixed together by adhesive or the like to be used as a laminated core. Once one punching cycle is complete, the punch 12 and stripper plate 16 rise, and the next processing area of the workpiece 18 is conveyed between the punch 12 and die 14 by the rotation of rollers or the like.
[0014] Vibration acceleration sensors 22 are mounted on the side and surrounding area of the die 14. These vibration acceleration sensors 22 have the function of detecting the vibration acceleration generated by the punching process by the punch 12 and sending it to the information processing device 24 wirelessly or via wired connection. The information processing device 24 consists of a PC equipped with, for example, a vibration acceleration analysis program.
[0015] Figure 2(a) shows the waveform of vibration acceleration transmitted from the vibration acceleration sensor 22, and it is shown that a large waveform 30 is observed each time punching occurs by the punch 12. In this invention, as shown in Figure 2(b), the maximum value of each waveform 30 of vibration acceleration observed during the punching process by the punch 12 is defined as the "maximum acceleration". According to Newton's equation of motion (F = m × a), reducing the acceleration a can reduce the force F, which in turn leads to a reduction in the mold load.
[0016] Figure 3 is an enlarged cross-sectional view of the cutting edge portion of the punch 12. The first edge located at the tip of the punch 12 is defined as "E1," the second edge located further back is defined as "E2," the inclined surface connecting the first edge E1 and the second edge E2 is defined as 12a, the horizontal distance between the first edge E1 and the second edge E2 is defined as "shear width W1," the vertical distance between the first edge E1 and the second edge E2 is defined as "shear height L," the angle between the inclined surface 12a and the horizontal plane H is defined as "shear angle θ," and the width of the punch 12 is defined as "punch width W2." In other words, the shear 40 of the punch 12 is composed of the first edge E1, the second edge E2, and the inclined surface 12a. In the case of this punch 12, "shear width W1 = punch width W2."
[0017] This invention aims to reduce the load on the die and the burrs on the punched material 20 formed by the punching process by optimizing the shear angle θ applied to the punch 12. For this purpose, multiple punches 12 with different shear angles θ were prepared, and punching was performed on the workpiece 18. An experiment was conducted in which the maximum acceleration and the height of the formed burrs (hereinafter referred to as "burr height") were measured.
[0018] Figure 4 is a graph showing the experimental results, illustrating the relationship between maximum acceleration and burr height when the shear angle θ is varied 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 (i.e., the mold load decreases), while the burr height tends to increase. Furthermore, when using a so-called edge punch with a shear angle θ = 0, the burr height is minimized, but the maximum acceleration value is highest, indicating that the mold load is maximized.
[0019] Figure 5 is an SEM image showing the state of die 14 before press working. Naturally, there is no damage whatsoever around the through hole 14a, and a clean edge is visible. Next, Figure 6 shows the state of die 14 after 500 punching cycles with an edge punch with a shear angle θ = 0. It shows that a large chip has formed on the edge of the through hole 14a.
[0020] In contrast, Figure 7 shows the state of die 14 after 20,000 punching cycles with a punch with a shear angle θ = 0.23 degrees. No significant chipping occurs, and the clean edge condition is maintained, almost the same as before processing. As a result, it has been proven that by applying an appropriate shear 40 to the punch 12 side, the lifespan of die 14 can be extended by at least 40 times.
[0021] Incidentally, even when using punches with a shear angle θ = 0.68 degrees and punches with a shear angle θ = 1.14 degrees, it was confirmed that no damage occurred to die 14 after 20,000 punching cycles, similar to the above. Therefore, from the perspective of extending the lifespan of the press die, a punch with a shear angle θ = 1.14 degrees is also suitable, but from the perspective of the quality of the punched material, problems were observed.
[0022] Specifically, Figure 8(a) is an SEM image 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 with a height of 0.025 mm is formed with a punch with a shear angle θ = 1.14 degrees.
[0023] On the other hand, Figure 9(a) is an SEM image showing the edge portion of the 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 figures, the punch with a shear angle θ = 0.68 degrees only forms a relatively small burr 20a with a height of 0.011 mm.
[0024] Assuming that a core is formed by laminating multiple punched material sheets 20, the burr height of each punched material must be kept within 0.02 mm in order to maintain its quality (parallelism between the top and bottom surfaces). 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] By the way, the relationship between shear height L, shear angle θ, and shear width W1 is expressed by the following trigonometric function equation 1: [Equation 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 → Shear height L: 0.008 mm (2) When the shear angle θ is 0.068 degrees → Shear height L: 0.024 mm However, with the current level of metalworking technology, it is only possible to achieve a shear height of 0.1 mm, and it is not realistic to impart ultra-fine shear heights 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 for the shear width W1 is as follows: (1) When the shear angle θ is 0.023 degrees → Shear width W1: 25 mm or more (2) When the shear angle θ is 0.068 degrees → Shear width W1: 9 mm or more
[0027] In this embodiment, the thickness T of the workpiece (high-strength soft magnetic foil material) 18 is coincidentally assumed to be 0.1 mm, thus leading to the relationship "shear height L ≥ thickness T". Previously, it was recognized that the limit of shear height was about 50% of the workpiece thickness from the viewpoint of suppressing burr height, but through this experiment, it was confirmed that in the case of high-strength soft magnetic foil material, even if a shear height exceeding 100% of the thickness is applied to the punch 12, the burr height can be kept to 0.02 mm or less.
[0028] In the above description, a punch 12 having only an inclined surface 12a at the cutting edge portion was used as an example, but this 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. Even in this case, the punch 12 is required to satisfy the following conditions: (1) Shear angle θ: within the range of 0.023 to 0.68 degrees (2) Shear height L: 0.1 mm or more (3) Shear width W1 when the shear angle θ is 0.023 degrees: 25 mm or more (4) Shear width W1 when the shear angle θ is 0.068 degrees: 9 mm or more 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)".
[0029] 10 Pressing machine 12 Punch 12a Inclined surface of punch 12b Flat surface of punch 14 Die 14a Through hole of die 16 Stripper plate 18 Workpiece 20 Punched material 20a Burr of punched material 22 Vibration acceleration sensor 24 Information processing device 30 Waveform of vibration acceleration 40 Shear E1 First edge of punch E2 Second edge of punch E3 Third edge of punch H Horizontal surface L Shear height θ Shear angle W1 Shear width W2 Punch width W3 Flat surface width
Claims
1. A press working apparatus comprising a punch and a die, wherein a plate-shaped workpiece conveyed between the punch and the die is punched out by the downward movement of the punch, and the punched workpiece is recovered as a product, wherein the workpiece is made of a high-strength soft magnetic foil material, a shear is provided only on 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, the punch further has a multi-stage shape having a flat surface connected to the inclined surface, and the shear angle, which is the angle between the horizontal surface in contact with the first edge and the inclined surface, is set within a range of 0.23 to 0.68 degrees such that the burr height of the punched workpiece is kept within 0.02 mm.
2. The press working apparatus according to claim 1, characterized in that the shear height, which is the distance between the second edge and the horizontal plane, is set to be greater than or equal to the plate thickness of the workpiece.
3. The press working apparatus according to claim 1 or 2, characterized in that the high-strength soft magnetic foil material is an iron-based amorphous alloy foil.
4. A method for manufacturing a laminated core, characterized by stacking a plurality of processed objects punched out by the press working apparatus described in claim 1 and recovered as products, and fixing the gaps between each processed object.
5. A press working device comprising a punch and a die, wherein a plate-shaped workpiece conveyed between the punch and the die is punched out by the downward movement of the punch, and the punched workpiece is recovered as a product, wherein the workpiece is made of a high-strength soft magnetic foil material, a shear is provided only on 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, the punch further has a multi-stage shape having a flat surface connected to the inclined surface, and the shear angle, which is the angle between the horizontal surface in contact with the first edge and the inclined surface, is set within the range of 0.23 to 0.68 degrees, thereby keeping the burr height of the punched workpiece within 0.02 mm.