Press punch and press apparatus equipped therewith

Abstract

[Problem] To provide a punch for press working in which a resonance point can be easily adjusted without weakening the punch strength, regardless of shape and material, and regardless of symmetry, and in which the punch function and the quality of press working can be improved, and a press working device equipped with the punch. [Solution] The punch is mounted on an upper die of the press working device and is driven by a vibrator. The cross-sectional shape of the punch in a horizontal plane orthogonal to a vertical plane including a center line in a punch direction has a structure having plane symmetry with respect to the vertical plane. A flange-shaped holding part is provided on an outer peripheral edge or a side surface of an intermediate part in the punch direction of the punch, while a first through-hole is bored in an upper side punch body on the upper side of the holding part, and a second through-hole is bored in a lower side punch body on the lower side of the holding part.

Description

[[Technical Field]]

[0001] The present invention relates to a press-working punch mounted on an upper die of a press working apparatus and driven by an oscillator, and a press working apparatus provided with the same, and particularly relates to a press-working punch which is provided with vertically separated through holes in a flange-shaped holding portion provided on the outer peripheral edge or outer side surface of the punch, whereby the functional performance of the punch can be easily adjusted and working accuracy can be improved, and a press working apparatus provided with the same. The press-working punch according to the present invention has a structure in which a cross-sectional shape on a horizontal plane orthogonal to a vertical plane including a center line in the punch direction is plane-symmetric with respect to the vertical plane, and an oscillator is arranged at a top portion on the center line when the punch is mounted on a press working apparatus. [[Background Art]]

[0002] In general, separation working, forming working and the like are known as press working, and apparatuses used for these types of working are generally called press working apparatuses. A press working apparatus places a workpiece between a die consisting of an upper die and a lower die, sandwiches and presses the workpiece between the upper die and the lower die, and processes the workpiece into a desired shape.

[0003] Separation working forms a shape by cutting the workpiece. For example, blanking, in which a workpiece is placed on a lower die and a shape is cut out by the upper die, is known. In addition, as forming working, for example, bending working for bending a workpiece, drawing working for stretching and forming a workpiece, and the like are known. However, in separation working, "burrs" and "roll-over" occur at the start and end portions of a sheared surface, and the states of these burrs and roll-over vary depending on the thickness and type of the workpiece plate, working speed, clearance, and other factors. When a large amount of roll-over occurs, the flatness of the sheared surface is impaired, which causes a problem when the flatness of the sheared surface is required. In addition, since burrs have sharp tips, they can cause personal injury, product chipping, and defects.

[0004] In forming processes, the thickness and type of the workpiece, processing speed, clearance, etc., may lead to a decrease in quality due to the occurrence of "scratches" or "cracks" during bending. Similarly, in drawing processes, the thickness and type of the workpiece, processing speed, clearance, etc., may lead to the occurrence of "wrinkles" or "cracks." [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6427438 [Overview of the project] [Problems that the invention aims to solve]

[0006] As a solution to the above-mentioned problems, for example, a press working apparatus and punch shown in Japanese Patent No. 6427438 (Patent Document 1) are known. Specifically, as shown in Figure 1, the press working apparatus 1 has a movable side portion (upper die) 2 having a punch 10 and a fixed side portion 3 having a lower die 30. The movable side portion 2 has a punch 10, a hold plate 21A and a back plate 21B that fix the punch 10, and a support 23 that fixes the hold plate 21A and the back plate 21B to the upper die holder 22. The upper die holder 22 and the support 23 are fixed with bolts 24A, and similarly the support 23 and the hold plate 21A and the back plate 21B are fixed with bolts 24B. The punch 10 is held and fixed by the hold plate 21A and the back plate 21B at a flange-shaped holding portion 11 that is provided around the middle of the punch, and the rest of the punch is not fixed. In other words, when the vibrator 20 vibrates the punch 10 up and down, that vibration is not transmitted to the stripper 25 or the support 23.

[0007] Furthermore, the movable side portion 2 includes a stripper 25 for removing the workpiece W when it adheres to the punch 10, a spring 26 for biasing the stripper 25 toward the lower die 30, and a guide pin 27 for stabilizing the position of the stripper 25. In addition, a vibrator 20 driven by a drive unit is fixedly disposed on the vibrating end (upper surface) of the punch 10.

[0008] On the other hand, the fixed side portion 3 includes a lower die 30 and a lower die holder 32 for fixing the lower die 30. The lower die 30 is a metal member having a predetermined thickness and is stacked on the lower die holder 32 and fixed by bolts 34. The lower die 30 also has a hole 31 with a shape corresponding to the shape of the punch 10 and a hole 33 for receiving the guide pin 27. The press working apparatus 1 is equipped with a drive mechanism (not shown) for applying the force necessary for processing to the die, a control mechanism (not shown) for controlling the drive mechanism (not shown), a safety device (not shown), and the like.

[0009] Figure 2 shows an example of a punch, where Figure 2(A) is a perspective view and Figure 2(B) is a front view in the X direction. In this example, the punch 10 has a rectangular horizontal cross-section, with flange-shaped holding portions 11 provided midway along both sides, and through holes 12 drilled laterally by cutting out a portion of the holding portions 11. The through hole 12 is a single hole distributed vertically with respect to the position of the holding portions 11. The through hole 12 is elongated in the vertical direction.

[0010] Figure 3 shows the structure (plan and side views) of the rectangular cross-section punch 10 and a cross-sectional view of how the holding part 11 of the punch 10 engages with the upper punch plate 21A and back plate 21B. The holding part 11 is provided in a flange-like manner on the outer surface (2 surfaces) of the middle part of the punch 10. Specifically, Figure 3(A) is a plan view of the punch 10, and the connection part 20A of the vibrator 20 is provided by a screw hole at the top of the punch on the center line, and the joint surface of the vibrator 20 and the punch 10 is in a structure that is pressed together. For example, by applying pressure to the joint surface, such as the axial force of a screw or press-fitting, and maintaining surface pressure, the vibration of the vibrator 20 is transmitted to the punch 10 well and stably. Figure 3(B) is a side view, and Figure 3(C) is a cross-sectional view showing how the holding part 11 is grasped and held by the punch plate 21A and back plate 21B.

[0011] Figure 4 shows an example of a punch 10A with a circular cross-section, where Figure 4(A) is a perspective view and Figure 4(B) is a side view in the Y direction. In this example, the punch 10A has a circular cross-section in the horizontal direction, and a flange-shaped retaining portion 11A is provided around the middle of the side surface. A through hole 13 is drilled laterally by cutting out a part of the retaining portion 11A, and the through hole 13 is a single hole distributed vertically relative to the surface of the retaining portion 11A. The through hole 13 is also elongated in the vertical direction.

[0012] In this configuration, the punch used in press working is selected according to the type of processing and the workpiece W. The workpiece W, placed on the upper surface of the lower die 30, is separated by the reciprocating motion of the punch 10 (or 10A) driven by the drive mechanism and the vertical vibration of the vibrator 20. At that time, the processing quality is improved by the resonance effect based on the through hole 12 (13) drilled in the punch 10 (10A).

[0013] However, conventional punches have a problem of reduced punch strength because a portion of the holding part is notched to accommodate the through hole. Also, the presence of a notch in the holding part makes it difficult to provide a D-cut for rotation prevention and positioning, especially in cylindrical punches. Furthermore, because the through hole drilled through the holding part expands and contracts vertically and horizontally due to vibration, the holding part moves laterally (perpendicular to the center line), causing frictional losses between the holding part and the punch plate and between the holding part and the back plate, which worsens the effectiveness of vibration transmission.

[0014] In conventional punches, the through-hole, designed to reduce rigidity, simultaneously cuts out a portion of the holding part for fixation. Because this cutout is located almost in the center of the through-hole, the through-hole expands and contracts both vertically and horizontally in response to vertical vibrations. As a result, the holding part 11, which is gripped for fixation, moves perpendicular to the vibration, as shown in the displacement distribution diagram of Figure 5. Therefore, depending on whether the gripping force is firm or loose, the punch may not move or may move easily. Depending on the degree of this, the resonance point of the punch shifts vertically, as described later, and the lateral amplitude is large. Combined with the gripping force, this generates friction and heat, causing fluctuations in vibration energy loss. Furthermore, there are drawbacks such as wear of the material due to friction and changes in the resonance point and lateral amplitude over time due to a decrease in gripping force. Note that the arrows in Figures 5(A) and (B) do not indicate the direction of displacement, but rather the lateral amplitude (0.010 mm).

[0015] Even punches without notches in the holding section suffer from similar problems because conventional punches exhibit large lateral amplitude.

[0016] The punch shown in Patent Document 1 assumes vertical symmetry with respect to the holding portion, and the resonance point of the entire punch is aligned with a through hole (elongated hole) that promotes lateral deformation (Poisson's ratio) due to vertical vibration, so it does not work with punches that are highly asymmetrical.

[0017] The present invention has been made in light of the circumstances described above, and the object of the present invention is to provide a press punch and a press working apparatus equipped therewith that can be easily adjusted for resonance points regardless of shape, material, and upper and lower symmetry, without weakening the punch strength, thereby improving punch function and improving the quality of press working. In the press punch of the present invention, the rigidity and weight (mass) can be adjusted upper and lower, with the position of the holding part acting as a boundary, so it can be used not only for upper and lower symmetrical shapes but also for highly asymmetrical shapes. [Means for solving the problem]

[0018] The present invention relates to a punch mounted on the upper die of a press working apparatus and driven by a vibrator. The above objective of the present invention is achieved by the fact that the cross-sectional shape of the punch in a horizontal plane perpendicular to a vertical plane containing the center line in the punch direction has a structure symmetrical with respect to the vertical plane, a flange-shaped holding portion is provided on the outer peripheral edge or side surface of the middle portion of the punch in the punch direction, a first through hole is drilled in the upper punch body above the holding portion, and a second through hole is drilled in the lower punch body below the holding portion. This is achieved by a press working apparatus equipped with the press working punch, the vibrator being disposed at the top of the punch on the center line.

[0019] The present invention relates to a punch mounted on the upper die of a press working apparatus. The above objective of the present invention is achieved by a press working apparatus that includes a punch with a circular cross-section, a flange-shaped holding portion provided without notches around the outer edge of the middle portion of the punch, a first through hole drilled in the upper punch body above the holding portion, and a second through hole drilled in the lower punch body below the holding portion, and by the resonance effect of the first through hole, the second through hole, the upper punch body, and the lower punch body, the position of the holding portion becomes a node of vibration displacement with respect to vertical vibration applied to the top of the punch, and the top of the upper punch body and the bottom of the lower punch body become antinodes of the vibration displacement, respectively. The objective of the present invention is achieved by a press working apparatus that includes the press working punch and has a vibrator disposed on the top of the punch.

[0020] Furthermore, the present invention relates to a punch mounted on the upper die of a press working apparatus, and the above objective of the present invention is achieved by a press working apparatus equipped with the press working punch, wherein a flange-shaped holding portion without a notch is provided opposite to the outer surface of the middle portion of a punch with a rectangular cross-section, a first through hole is drilled in the upper punch body above the holding portion, and a second through hole is drilled in the lower punch body below the holding portion, and the position of the holding portion becomes a node of vibration displacement with respect to vertical vibration applied to the top of the punch, and the top of the upper punch body and the bottom of the lower punch body become antinodes of the vibration displacement, respectively, and this is achieved by a press working apparatus equipped with the press working punch and having a vibrator disposed on the top of the punch.

[0021] Furthermore, the present invention relates to a punch mounted on the upper die of a press working apparatus and driven by a vibrator. The above objective of the present invention is achieved by the fact that the cross-sectional shape of the punch in a horizontal plane perpendicular to a vertical plane containing the center line in the punch direction is a barrel-shaped cross-section symmetrical with respect to the vertical plane, a flange-shaped holding portion is provided opposite to the outer surface of the middle part of the punch, a first through hole is drilled in the upper punch body above the holding portion, and a second through hole is drilled in the lower punch body below the holding portion, and the position of the holding portion becomes a node of vibration displacement with respect to vertical vibration applied to the center of the top of the punch, and the top of the upper punch body and the bottom of the lower punch body become antinodes of the vibration displacement, respectively, due to the resonance effect of the first through hole, the second through hole, the upper punch body, and the lower punch body. [Effects of the Invention]

[0022] The punching punch of the present invention has a punch cross-sectional shape on a horizontal plane orthogonal to a vertical plane including the center line in the punching direction that is plane-symmetric with respect to the vertical plane, which reduces lateral deformation caused by longitudinal vibration of the holding portion provided on the outer peripheral edge or outer surface, reduces wear of the gripped holding portion and loss due to friction, and also reduces changes in vibration characteristics caused by the gripping force. In addition, since no notch in the holding portion provided on the outer peripheral edge or outer surface is required, the punch can be firmly held and fixed without reducing strength. Furthermore, in the present invention, through-holes are provided respectively in the punch body above and below the holding portion. Although steel material is used for the punch body, the weight is increased by the cutting edge at the tip, and by actively adjusting the weight distribution, it is possible to adjust only the lower punch body. In this way, since the vibrator side and the punch tip side can be adjusted independently, the resonance points of the vibrator side and the punch tip side can be easily matched. Therefore, vibration transmission is possible even when the holding portion is firmly fixed.

[0023] As a factor that promotes vertical asymmetry, in punch maintenance, polishing is performed to keep the worn or chipped blade at the end sharp (square). After several maintenance operations, polishing of the blade may reach 10 mm or more from the new state, which promotes vertical asymmetry across the holding portion. In such a case, the frequency on the punch tip side acts in an increasing direction, and the rigidity on the punch tip side decreases, but according to the present invention, correction can be easily performed by expanding the through-hole for processing. Especially when only the tip uses super steel, the main body is still steel, so expanding processing of the through-hole is easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] [Figure 1] It is a configuration diagram showing an example of a general press working apparatus. [Figure 2] These are a perspective view and a side view showing an example of a punch. [Figure 3] These are a plan view, a front view, and a cross-sectional structural view showing a structural example and a holding example of a punch. [Figure 4] These are a perspective view and a side view showing another example of a punch. [Figure 5] This is a displacement distribution diagram showing two examples of the characteristics of conventional punches. [Figure 6] These are a front view and a side view showing an example of a punch according to the present invention. [Figure 7] These are a side view of the mechanism and a characteristic diagram for explaining the principle of the present invention. [Figure 8] This is a structural diagram (plan view and side view) for illustrating the present invention in comparison with conventional examples. [Figure 9] This is a characteristic diagram showing the effects of the present invention and the conventional example (presence or absence of through holes). [Figure 10] This is a characteristic diagram showing the effect (vertical displacement) of the present invention and the conventional example. [Figure 11] This is a characteristic diagram showing the effect (grasping ability) of the present invention and the conventional example. [Figure 12] This is a characteristic diagram showing the effect (lateral amplitude) of the present invention compared to the conventional example. [Figure 13] This is a characteristic diagram illustrating the effects (displacement and transverse amplitude) of the present invention. [Figure 14] These are perspective and side views illustrating another example of the punch according to the present invention. [Figure 15] This is a front view showing another example of a punch according to the present invention. [Figure 16] This is a plan cross-sectional view showing another example of a through-hole provided in a punch according to the present invention. [Figure 17] This is a front view showing another example of a punch to which the present invention can be applied. [Figure 18] This is a plan view showing an example of mounting a retaining part in a punch with a rectangular cross-section. [Figure 19] These are perspective and plan views showing an example of a punch with a barrel-shaped cross-section. [Figure 20] These are perspective and plan views showing other examples of punches with a barrel-shaped cross-section. [Figure 21] These are cross-sectional and plan views showing an example of a punch with a cross-section resembling a skewer of dumplings. [Figure 22] These are cross-sectional and plan views showing an example of a punch with a trumpet-shaped cross-section at both ends. [Figure 23]These are cross-sectional and plan views showing an example of a punch with a barbell-shaped cross-section. [Figure 24] These are cross-sectional and plan views showing an example of a punch with a cross-section shaped like a drum. [Modes for carrying out the invention]

[0025] Conventional punches are based on the premise of a homogeneous punch material and equal wavelength, and it is desirable that they be vertically symmetrical with respect to the holding portion provided on the periphery or outer surface of the punch. However, depending on the type of press work, vertical symmetry is not always possible. The present invention improves performance even for punches with strong vertical asymmetry by independently adjusting the stiffness distribution and weight distribution on the transducer side and the punch tip side with respect to the holding portion, thereby matching the resonance points (frequency at which the vibration is strongest) on the transducer side and the punch tip side. Furthermore, the punch according to the present invention has a cross-sectional shape of a horizontal plane perpendicular to a vertical plane containing the center line in the punch direction (vertical direction), which is symmetrical with respect to the vertical plane, and the transducer is positioned on the center line when mounted on a press work machine.

[0026] In other words, as shown in Figure 6, in the present invention, a flange-shaped holding portion 101 (thickness D) is provided around the outer edge of the punch 100 at the middle of the punching direction (vertical direction) without any notches. A rectangular cross-section through hole 110 is drilled in the upper punch body (vibrator side) of the punch 100 relative to the holding portion 101, and a rectangular cross-section through hole 111 is drilled in the lower punch body (punch tip side) of the punch 100. Then, due to the resonance effect of the through holes 110, 111 and the punch body, as shown in Figure 7(A), the position of the holding portion 101 becomes a node (displacement = 0) of the displacement (vibration) caused by the vibrator applied to the top of the punch 100, and as shown in Figure 7(B), the top of the upper punch body and the bottom of the lower punch body become antinodes (maximum displacement) of the displacement (vibration), respectively, by adjusting the rigidity and weight (mass) of the punch body. The adjustment of rigidity and weight is carried out by adjusting the size of the through holes 110 and 111. In this example, through holes 110 and 111 are drilled parallel to each other through the centerline. As shown in Figure 7(B), the displacement increases sharply from 0 [mm] near the top of the node (region AR), reducing the cross-sectional area of ​​the part acting as a spring. The same applies to the area near the bottom of the node (region BR). In other words, increasing the size of the through holes 110 and 111 is effective in lowering the resonance point, which also effectively reduces the spring stiffness and increases the amplitude.

[0027] The positional relationship between the holding portion 101 and the through holes 110 and 111 is such that the top surface of the holding portion 101 and the bottom surface of the through hole 110 are close together (including contact or partial cutting), and the tops of the holding portion 101 and the through hole 111 are close together (including contact or partial cutting). The cross-sectional shape of the through holes 110 and 111 can be circular, elliptical, rectangular, etc., but the cross-sectional shape is arbitrary as long as the following conditions are met. The natural frequency Fn of the punch 100 is given by the following equation 1, where k is the spring constant and m is the mass.

[0028]

number

[0029] In this invention, since there are no notches in the holding portion 101 which is provided around the outer edge of the punch 100 or facing the outer surface, the required rigidity and strength can be maintained without reducing the rigidity and strength of the punch 100. Even if the punch has a shape with strong vertical asymmetry with respect to the holding portion 101, the resonance effect can be further increased by independently adjusting the through holes 110 and 111. That is, the resonance effect can be increased by aligning the resonance point on the vibrator side due to the through hole 110 with the resonance point on the punch tip side due to the through hole 111. The holding portion 101 is a node of vibration and does not have a vibration adjustment function, and since the holding portion 101 is not notched, the function of the holding portion 101 is to position and hold it using the conventional punch plate 21A and back plate 21B as shown in Figure 3(C). However, even without notches in the holding portion 101, the positioning and holding functions are not reduced, and the vibration characteristics can be adjusted. This solves the conventional problem of cutting out a through hole in part of the aforementioned holding portion, while maintaining strength and rigidity, allowing it to be assembled between the punch plate 21A and the back plate 21B, and enabling easy processing of D-cuts for positioning.

[0030] Next, we will explain how to align the resonance points of the upper part of the punch (the vibrator side) and the lower part of the punch (the punch tip side). The vibrator side and the punch tip side of the punch have different requirements due to the characteristics of the mechanism. For example, the vibrator side needs to be shortened to keep the overall height of the mold low, but simply shortening it increases rigidity but decreases weight, both of which act to raise the resonance point. On the other hand, the punch tip side needs to maintain a certain length in order to perform functions such as stripper, punch plate, and press stroke, and this acts to lower the resonance point compared to the vibrator side. To address these trade-off requirements, comprehensive measures are needed for each. In the case of a cutting-edge carbide punch, where the punch body is made of steel and carbide is placed in the punch tip where wear is severe, or a two-hole simultaneous punching punch with two cutting blades at the tip, the rigidity and weight of the same part increase, which also lowers the resonance point, so it is important to make it easier to deal with these types of designs.

[0031] In the punch 100 of a press working machine, as shown in Figures 7(A) and (B), it is desirable to achieve vibration with the holding part 101, which is sandwiched between the punch plate and back plate that serve as fixed points, as the node (displacement = 0), and the punch tip (up and down) as the antinode (maximum displacement). This is because the vibration of the vibrator at the top of the punch is largely transmitted to the punch tip. The length from the holding part 101 to the punch tip should not only fit the total height of the die within the die height of the press working machine, but also be an appropriate length considering the die's processing equipment, precision, and function. Dies used in applications operating at low SPM (Shots Per Minute) can be long, so in these cases, iron-based punches are often used. These iron-based punches have a large overall length and a lower Young's modulus than superhard materials, making it easy to align the position of the amplitude antinode with the punch tip. However, dies used in high-speed presses, especially those punching out electromagnetic steel sheets, are short, and superhard materials are used for the punch material. This ultra-hard punch, while heavier, has a higher Young's modulus. Combined with its short length, this causes the resonance to shift to the high-frequency side, making it difficult to align the vibration antinode with the punch tip. Specifically, to efficiently transmit vibration frequencies of approximately 10-30 kHz from the transducer to the punch tip, it is necessary to resonate throughout the entire punch without attenuating the set frequency. The holding section 101 acts as a node in the vibration. As shown in Figure 6(B), when the length on the punch tip side is L1 and the length on the transducer side is L2, the length L1 on the punch tip side is determined by the mold structure and the material used. At the same time, the length L2 on the transducer side is also subject to different constraints due to the mold structure and the use of the press equipment, so lengths L1 and L2 are not equal in length. Therefore, the rigidity and resonance frequency (wavelength) differ on either side of the holding section 101. Unless the cross-sectional shape of the punch body is changed at lengths L1 and L2 to adjust the rigidity, it is not possible to obtain resonance with the tip as the antinode.

[0032] Based on these premises, the method for adjusting the resonant frequency will be explained. As mentioned above, lengths L1 and L2 are different, and length L1 is strongly constrained by the mold structure and application. Therefore, under these conditions, resonance with the oscillation frequency with the holding part 101 as a node must be obtained. Accordingly, the rigidity and weight of the punch 100 are adjusted by the cross-sectional shape of length L1 on the punch tip side and length L2 on the punch vibrator side. The holding part 101 is not notched to obtain rigidity that acts as a node in vibration, and the rigidity and weight distribution on both the upper and lower sides of the holding part 101 are adjusted. By adjusting the rigidity and weight in this way, the resonant frequencies on the vibrator side and the punch tip side can be adjusted. In this invention, rigidity is adjusted by reducing the area of ​​the cross-sectional shape (perpendicular to the centerline direction) on both the upper and lower sides of the holding part 101, and weight is also adjusted by increasing the area of ​​the cross-sectional shape. This adjusted cross-sectional shape is also effective in adjusting the dimensions in the longitudinal direction in the axial direction. Accordingly, the following adjustment requirements (1) to (3) are met. (1) In tool horns of different lengths L1 and L2, the rigidity and weight are adjusted by different cross-sections in each of the L1 and L2 sections. (2) In adjusting the cross-sectional area that reduces rigidity, the through-hole should be close to the surface of the holding part (the closer it is, the more effective it is, and contact is best). (3) Regarding the adjustment of the increase / decrease gradient of the weight distribution (especially the decrease), the through-hole should be close to the surface of the holding part (the closer, the more effective, and contact is best).

[0033] As shown in Figure 6, in the present invention, a retaining portion 101 without a notch is provided around the periphery of the middle part of the punch 100, which has a circular cross-section. A through hole 110 with a substantially rectangular cross-section is provided in the punch body on the upper side of the upper surface of the retaining portion 101, and a through hole 111 with a substantially rectangular cross-section is provided in the punch body on the lower side of the lower surface of the retaining portion 101. That is, the upper and lower punch bodies are provided with separate through holes 110 and 111, respectively, which are arranged parallel to each other through the center line and are close to the retaining portion 101. The thickness of the retaining portion 101 is D, the length from the bottom surface of the punch 100 to the bottom surface of the retaining portion 101 (punch tip side length) is L1, and the length from the top surface of the punch 100 to the top surface of the retaining portion 101 (punch vibrator side length) is L2.

[0034] The size (diameter) and shape of the through holes 110 and 111 are adjusted according to the specifications described above and are drilled into the upper and lower punch bodies, respectively. Specifically, Figures 8(A1) to (C2) show a plan view (A1) and a front view (A2) of a punch with a rectangular cross-section, in the case with a holding part but no through holes; a plan view (B1) and a front view (B2) of the present invention shown in Figure 6, in the case with a holding part 101, through holes 110 and 111, and without a notch in the holding part 101, where the through holes 110 and 111 are separated into upper and lower parts; and a plan view (C1) and a front view (C2) of a conventional example in which the holding part 11 has a notch and the through hole 12 penetrates vertically. In all cases, simple harmonic motion is applied from the vibrator mounting surface at the top of the punch. In the present invention, simple harmonic motion is applied from the vibrator contact surface 100A shown in Figure 8(B1), whereas in the conventional example, simple harmonic motion is applied from the vibrator mounting surface 20A shown in Figure 8(C1).

[0035] Figures 9 to 12 correspond to the punch structures shown in Figures 8(A) to 8(C), respectively: an example of a punch without a through hole (Figure 8(A)), an example of the punch of the present invention (Figure 8(B)), and an example of a conventional punch (Patent Document 1) (Figure 8(C)). The characteristics of each punch are compared item by item. Figures 9 to 12 all show results obtained by FEM (Finite Element Method).

[0036] Figure 9 shows whether the resonant frequency falls within the target frequency band. The present invention and the conventional example, which have through holes, are suitable. In the case without through holes, adjustment is not possible, and therefore the frequency does not fall within the target frequency band (or is difficult to achieve). Regarding the target frequency band, it is desirable to select the frequency from off-the-shelf products (certified, registered, and sold by manufacturers) as a set for the vibrator and oscillator. The original shape (without through holes) has the highest rigidity, so it is extremely difficult to raise the resonant frequency, and inevitably, it can only be manipulated in the direction of lowering the resonant point. Since one mold (press processing machine) may require dozens of different punches, if vibrator and oscillator sets can be reused with the same specifications, there is an advantage in minimizing costs, response time, and man-hours in terms of avoiding incorrect assembly and connection, handling damage, and equipment inventory. In addition, off-the-shelf vibrator and oscillator sets from manufacturers are certified and registered, and using anything other than those registered requires the time and effort of obtaining certification, which increases costs and the mold manufacturing schedule. However, using off-the-shelf products avoids these problems, and furthermore, transducer and oscillator sets come with a manufacturer's warranty, and there are advantages such as the availability of replacement parts in stock for repairs and support. Here, among manufacturers that handle transducers, for example, company A's product lineup consists of 15.15kHz, 19.15kHz, 28.5kHz, and 39.5kHz, and other intermediate frequencies cannot be used. Similarly, another manufacturer, company B, has a lineup of 15kHz, 20kHz, 27kHz, 28kHz, 30kHz, 39kHz, 40kHz, and 60kHz, and other intermediate frequencies cannot be used. The same applies to other manufacturers that handle transducers. Since there is no standard for unifying transducers, there is no compatibility between manufacturers, dimensions differ, and operating methods and peripheral equipment also differ. For this reason, in practice, it is necessary to select one manufacturer and operate within the range of their product lineup.

[0037] On the other hand, customizing the transducer and oscillator to match the shape and material of the punch results in a special specification, requiring individual design, manufacturing, and approval, which is significantly disadvantageous in terms of both cost and schedule. Therefore, the target frequency is selected from the manufacturer's lineup to meet the quality and requirements of the workpiece, or a customized specification is selected if necessary. Regarding the target frequency, various punch shapes and materials exist depending on the shape of the workpiece and the pressing process, each exhibiting different vibration characteristics. However, with the punch of this invention, the resonant frequency can be easily adjusted by drilling through holes at the top and bottom, so that the target frequency can be set to the frequency that is optimal for the quality and requirements of the workpiece, as shown in Figure 9.

[0038] Figure 10 shows a comparison of the amplitude (vertical displacement) of the punch tip caused by resonance, and it can be seen that the punch of the present invention has an amplitude about 0.003 mm larger than that of a conventional punch. A larger amplitude at the punch tip means a greater vibration effect, which improves the performance of press working. In contrast, when there is no through hole, the amplitude is small, and it can be seen that the vibration effect is considerably smaller than that of a conventional punch.

[0039] Figure 11 compares the resonant frequencies of the present invention punch and a conventional punch, comparing them based on the difference in gripping force between the punch plate 21A and the back plate 21B. When the gripping force is strong, the punch 100 is held firmly via the holding part 101, resulting in small lateral displacement. However, when the gripping force is weak, the lateral displacement increases, and the resonant frequency decreases. Specifically, when the gripping force is weak, the frequency decreases by 0.10 kHz in the case of no through hole, by 0.15 kHz for the present invention punch, and by 0.28 kHz for the conventional punch, showing a 46% reduction in fluctuation for the present invention punch compared to the conventional punch. Even with a weak gripping force, the present invention punch remains within the target frequency band even when the resonant frequency drops by 0.15 kHz. However, with a weak gripping force, the conventional punch's resonant frequency drops by as much as 0.28 kHz, causing it to fall outside the target frequency band. In the case of no through hole, the frequency falls outside the target frequency band regardless of whether the gripping force is strong or weak.

[0040] Figure 12 summarizes the displacements in Figures 5 and 13. Figure 13 shows the displacement distribution of the punch of the present invention in a state without gripping force, with a lateral amplitude of 0.002 mm. Figure 12 also shows a comparison of the lateral amplitudes of each specification. The lateral amplitude of the punch of the present invention is 0.002 mm, which is an 80% reduction compared to the 0.01 mm of the conventional punch, indicating a significant improvement in lateral amplitude.

[0041] Figure 14 shows another embodiment of the present invention, in which the holding portion 101 side of the through holes 110 and 111 is cut, and the upper and lower surfaces of the holding portion 101 constitute part of the through holes 110 and 111. Given the adjustment requirements (2) and (3) above, the configuration of the through holes in Figure 14 is the most desirable. Thus, the through holes 110 and 111 of the present invention do not have to be separated from the upper and lower surfaces of the holding portion 101, and the upper and lower surfaces of the holding portion 101 may form part of the through holes 110 and 111.

[0042] Furthermore, the examples in Figures 15(A) and (B) show that, as a result of adjusting the nodes and antinodes of the resonant frequency as described above, Figure 15(A) shows an example where the size and shape of the through holes 112 and 113 are different, and similarly, Figure 15(B) also shows an example where the size and shape of the through holes 114 and 115 are different. That is, in both cases, the upper punch body is longer and larger, so the upper through holes 112 and 114 are larger than the lower through holes 113 and 115, respectively. In the example in Figure 15(A), the cross-section of through hole 112 is elliptical and the cross-section of through hole 113 is circular, while in the example in Figure 15(B), the cross-sections of through holes 114 and 115 are both elliptical. Note that if the asymmetry between the upper and lower parts is extremely pronounced, the smaller through hole may have a size of 0.

[0043] Furthermore, in the examples described above, the through holes, separated vertically, are arranged in parallel, but they may also be arranged in a non-parallel positional relationship passing through the center line CL, for example, as shown in Figure 16.

[0044] In press-formed punches, for simultaneous punching of two holes using a single punch material, there are punches 126A and 126B provided on the tip side of the punch 120, as shown in Figure 17(A). Such a punch 120 is asymmetrical in shape, weight, and rigidity. Due to the die structure, the overall length of the punch is short, and the resonance point unintentionally becomes high, so it is necessary to lower the resonance point. The distance from the holding part 121 to the punch tip remains unchanged, but the weight of the tip becomes lighter, resulting in a higher frequency. Therefore, the rigidity of the tip side is reduced while maintaining weight. On the transducer side, in order to lower the frequency and make it equivalent to the tip side, the rigidity near the holding part 121 is reduced while maintaining the weight of the end, and the resonance point is tuned. In Figure 17(A), range 122 is the heavy part with small deformation on the transducer side, and range 125 is the heavy part with small deformation on the punch tip side, both of which are weight adjustment parts. Furthermore, range 123 is the spring section on the transducer side that experiences significant deformation, and range 124 is the spring section on the punch tip side that experiences significant deformation; both are rigidity adjustment sections.

[0045] Furthermore, in press-work punches, to increase the lifespan of the cutting edge and the amplitude of vibration, a cutting edge 134 made of superhard steel is attached to the tip of the punch 130, as shown in Figure 17(B). This punch is asymmetrical in terms of material, weight, and rigidity. The body of the punch 130 is made of steel with a density of 7720 kg / m³. 3 While the Young's modulus of steel is 2.10E+11, super steel has a density of 14050 kg / m³. 3 The Young's modulus is 5.20E+11, indicating strong asymmetry. In this example, due to the mold structure, the punch length is short, so it is necessary to lower the resonance point. The distance from the holding part 131 to the punch tip remains unchanged, and the tip is heavy, so there is little adjustment to the stiffness on the tip side (the diameter of the through hole 133B is small). However, on the transducer side, there is a distance from the holding part 131 to the top, so both the weight and stiffness are reduced (the diameter of the through hole 132A is large) to tune the resonance point.

[0046] As shown in Figure 17(B), when the punch body is made of steel and the tip is made of superhard steel with high Young's modulus and mass density, the asymmetry between the upper and lower parts is significantly disrupted. In such cases, a through hole is drilled only on the transducer side to lower the resonance point. In other words, the lower through hole 133B may be omitted.

[0047] In the examples described above, punches with a circular horizontal cross-section were mainly explained, but as shown in Figure 18, punches with a rectangular cross-section are also possible. Specifically, the example in Figure 18(A) is when non-notched retaining portions 141A and 141B are provided opposite each other on the outer surface of the punch 140 so as to be perpendicular to the through holes 142 and 143. The example in Figure 18(B) is when non-notched retaining portions 141C and 141D are provided opposite each other on the outer surface of the punch 140 so as to be parallel to the through holes 142 and 143. Furthermore, the example in Figure 18(C) is when non-notched retaining portions 141A and 141B are provided opposite each other on the outer surface of the punch 140 so as to be perpendicular to the through holes 142 and 143, and non-notched retaining portions 141C and 141D are provided opposite each other on the outer surface of the punch 140 so as to be parallel to the through holes 142 and 143. Even with this configuration, the same effects as described above can be obtained by drilling through holes 142 and 143.

[0048] In Figures 18(A) to (C), reference numeral 140A indicates the transducer mounting section, and in all cases, the transducer is positioned on the center line CL.

[0049] Furthermore, Figures 19 and 20 show examples of punches 150 with a barrel-shaped cross-section. Specifically, Figure 19(A) is a perspective view showing an example in which two parallel through holes 152 and 153 are provided perpendicular to the holding portion 151 on opposing outer surfaces, and the plan view is Figure 19(B). Similarly, Figure 20(A) is a perspective view showing an example in which two parallel through holes 152 and 153 are provided parallel to the holding portion 151, and the plan view is Figure 20(B). Even with punches having a barrel-shaped cross-section, the same effects as described above can be obtained.

[0050] In Figures 19 and 20, reference numeral 150A indicates the transducer mounting portion. In both cases, the transducer is positioned on the center line CL and is symmetrical with respect to the plane containing the center line CL.

[0051] The punch for press working according to the present invention has a cross-sectional shape in a horizontal plane perpendicular to a vertical plane containing the center line CL in the punching direction, and the cross-sectional shape has a structure that is symmetrical with respect to the vertical plane. When mounted on a press working device, a vibrator is positioned at the top of the center line CL. However, in addition to the circular, rectangular, and barrel-shaped cross-sections described above, the punch structure according to the present invention may also have cross-sectional shapes such as those described below.

[0052] Figure 21 shows a cross-sectional view of a punch 160 with a skewer-like cross-section, where holding portions 161 are provided at both ends of the skewer, and a vibrator is positioned on the center line CL. In this punch 160, a through hole 162 may be provided that passes through the center line CL and is perpendicular to the holding portion 161, as shown in Figure 21(A), or a through hole 163 may be provided that passes through the center line CL and is parallel to the holding portion 161, as shown in Figure 21(B).

[0053] Figure 22 shows a cross-sectional view of a punch 170 with a trumpet-shaped cross-section at both ends, with holding portions 171 provided at both ends, and a vibrator positioned on the center line CL. In this punch 170, a through hole 172 may be provided that passes through the center line CL and is perpendicular to the holding portion 171, as shown in Figure 22(A), or a through hole 173 may be provided that passes through the center line CL and is parallel to the holding portion 171, as shown in Figure 22(B).

[0054] Furthermore, Figure 23 shows a cross-sectional view of a punch 180 with a barbell-shaped cross-section, with holding portions 181 provided on both sides of the body, and a vibrator positioned on the center line CL. In this punch 180, a through hole 182 passing through the center line CL and parallel to the holding portion 181 may be provided as shown in Figure 23(A), or a through hole 183 passing through the center line CL and parallel to the holding portion 181 may be provided as shown in Figure 23(B).

[0055] Furthermore, Figure 24 shows a cross-sectional view of a punch 190 with a drum-shaped cross section, with holding portions 191 provided at both ends, and a vibrator positioned on the center line CL. In this punch 190, a through hole 192 passing through the center line CL and parallel to the holding portion 191 may be provided as shown in Figure 24(A), or a through hole 193 passing through the center line CL and perpendicular to the holding portion 191 may be provided as shown in Figure 24(B). [Explanation of Symbols]

[0056] 1. Pressing machine 2 Movable side part (upper mold) 3 Fixed side part 10, 10A Punch 11, 11A holding part 12, 13 Through holes 20 transducers 20A connection 21A Punch Plate 21B Backplate 22 Upper holder 23 Support 24A, 24B, 34 volts 25 Strippers 26 Spring 27 Guide pins 30 Lower mold 31,33 hole 32 Lower mold holder 100 punches 101 Holding part 110, 111 Through holes 112, 113, 114, 115 Through holes 120, 130, 140, 150 punches 160, 170, 180, 190 punches 126A, 126B, 134 cutting edge

Claims

1. It is a punch that is mounted on the upper die of a press working machine and driven by a vibrator. A punch for press working, characterized in that the horizontal plane shape, which includes the center line of the horizontal cross-section of the punch and is perpendicular to a vertical plane that divides the horizontal cross-section into two halves, has a structure that is symmetrical with respect to the vertical plane, a flange-shaped retaining portion is provided on the outer edge or side surface of the middle portion of the punch in the punching direction, a first through hole is drilled in the upper punch body above the retaining portion, and a second through hole is drilled in the lower punch body below the retaining portion.

2. The press punch according to claim 1, wherein the cross-sections of the first through-hole and the second through-hole are circular, elliptical, or rectangular.

3. The press punch according to claim 1 or 2, wherein the cross-sectional shape is circular, elliptical, rectangular, barrel-shaped, skewer-shaped, barbell-shaped, trumpet-shaped at both ends, or bell-shaped.

4. A press working apparatus comprising the press punch described in claim 1, wherein the vibrator is disposed on the top of the punch on the center line.

5. A press punch, mounted on the upper die of a press working machine, has a circular cross-section punch with a flange-shaped holding portion around the outer edge of the middle section, a first through hole is drilled in the upper punch body above the holding portion, and a second through hole is drilled in the lower punch body below the holding portion, characterized in that, due to the resonance effect of the first through hole, the second through hole, the upper punch body, and the lower punch body, the position of the holding portion becomes a node of vibration displacement with respect to vertical vibration applied to the top of the punch, and the top of the upper punch body and the bottom of the lower punch body are antinodes of the vibration displacement, respectively.

6. The press punch according to claim 5, wherein the holding portion is not provided with a notch.

7. The press punch according to claim 5 or 6, wherein the first through hole and the second through hole are arranged in parallel, the bottom of the first through hole is close to the upper surface of the holding portion, and the top of the second through hole is close to the lower surface of the holding portion.

8. The press punch according to claim 5 or 6, wherein the first through hole and the second through hole are provided non-parallel, the bottom of the first through hole is close to the upper surface of the holding portion, and the top of the second through hole is close to the lower surface of the holding portion.

9. The press punch according to claim 5 or 6, wherein the cross-sections of the first through-hole and the second through-hole are circular, elliptical, or rectangular.

10. A press working apparatus comprising a press punch as described in claim 5, wherein a vibrator is disposed on the top of the punch.

11. A press punch, mounted on the upper die of a press working machine, is characterized in that a flange-shaped holding portion is provided opposite to the outer surface of the middle portion of a punch with a rectangular cross-section, a first through hole is drilled in the upper punch body above the holding portion, and a second through hole is drilled in the lower punch body below the holding portion, and due to the resonance action of the first through hole, the second through hole, the upper punch body, and the lower punch body, the position of the holding portion becomes a node of vibration displacement with respect to vertical vibration applied to the top of the punch, and the top of the upper punch body and the bottom of the lower punch body are antinodes of the vibration displacement, respectively.

12. The press punch according to claim 11, wherein the first through hole and the second through hole are arranged in parallel, and the holding portion is provided on an outer surface perpendicular to or parallel to the first through hole and the second through hole.

13. The press punch according to claim 11, wherein the first through hole and the second through hole are arranged non-parallel to each other, and the holding portion is provided on an outer surface perpendicular to the first through hole and the second through hole and on an outer surface parallel to the first through hole and the second through hole, respectively.

14. The press punch according to any one of claims 11 to 13, wherein the cross-sections of the first through-hole and the second through-hole are circular, elliptical, or rectangular.

15. A press working apparatus comprising a press punch as described in claim 7, wherein a vibrator is disposed on the top of the punch.

16. A punch for press working, mounted on the upper die of a press working machine and driven by a vibrator, wherein the horizontal plane shape perpendicular to a vertical plane that includes the center line of the horizontal cross-section of the punch and divides the horizontal cross-section into two halves is a barrel-shaped shape symmetrical with respect to the vertical plane, a flange-shaped holding portion is provided opposite to the outer surface of the middle part of the punch, a first through hole is drilled in the upper punch body above the holding portion, and a second through hole is drilled in the lower punch body below the holding portion, and due to the resonance action of the first through hole, the second through hole and the upper and lower punch bodies, the position of the holding portion becomes a node of vibration displacement with respect to vertical vibration applied to the top of the punch on the center line, and the top of the upper punch body and the bottom of the lower punch body are antinodes of the vibration displacement, respectively.

17. The press punch according to claim 16, wherein the cross-sections of the first through-hole and the second through-hole are circular, elliptical, or rectangular.

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