Punch for press working and press working device equipped with same

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

Press punch and press device equipped with same

[0001] The present invention relates to a press punch that is mounted on the upper die of a press machine and is driven by a vibrator, and to a press machine equipped with the same, and more particularly to a press punch that has separate upper and lower through-holes in a flange-shaped holding portion provided on the outer peripheral edge or surface of the punch, allowing the punch's functional performance to be easily adjusted and processing accuracy to be improved, and to a press machine equipped with the same. The press punch according to the present invention has a cross-sectional shape in a horizontal plane perpendicular to a vertical plane including a centerline in the punch direction that is plane-symmetrical with respect to the vertical plane, and when mounted in the press machine, a vibrator is disposed at the apex on the centerline.

[0002] Generally, press working includes separation working, molding working, etc., and the equipment used for these workings is generally called press working equipment. In press working equipment, a workpiece is placed between a mold consisting of an upper mold and a lower mold (die), and the workpiece is sandwiched between the upper and lower molds and pressed to work the workpiece into a desired shape.

[0003] Separation processes form shapes by cutting the workpiece. For example, punching, in which the workpiece is placed on a lower die and then cut out with an upper die, is known. Forming processes, such as bending and drawing, are also known. However, separation processes can produce burrs and sagging at the beginning and end of the sheared surface, and the state of these burrs and sagging varies depending on the thickness and type of the workpiece, the processing speed, clearance, and other factors. Excessive sagging can impair the flatness of the sheared surface, posing a problem when flatness of the sheared surface is required. Furthermore, burrs have sharp edges, which can cause injury to personnel and lead to product damage and defects.

[0004] In forming processes, there is a risk of quality degradation due to the occurrence of "scratches" and "cracks" during bending depending on the thickness and type of the workpiece, the processing speed, clearance, etc. In addition, in drawing processes, there is a risk of "wrinkles" and "cracks" occurring depending on the thickness and type of the workpiece, the processing speed, clearance, etc.

[0005] Patent No. 6427438

[0006] A press working apparatus and punch disclosed in Japanese Patent No. 6427438 (Patent Document 1) are known to solve the above-mentioned problems. Specifically, as shown in FIG. 1 , the press working apparatus 1 has a movable portion (upper die) 2 having a punch 10 and a fixed portion 3 having a lower die 30. The movable portion 2 has the punch 10, a hold plate 21A and a back plate 21B for fixing the punch 10, and a support 23 for fixing the hold plate 21A and the back plate 21B to an upper die holder 22. The upper die holder 22 and the support 23 are fixed with bolts 24A, and similarly, the support 23, 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 provided around the punch 10's midsection, and the punch 10 is not fixed at any other portion. In other words, when the punch 10 is vibrated up and down by the vibrator 20, the vibration is not transmitted to the stripper 25 or the support 23.

[0007] The movable portion 2 also has 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 attitude of the stripper 25. Furthermore, a vibrator 20 driven by a drive unit is fixedly disposed on the vibration end (upper surface) of the punch 10.

[0008] On the other hand, the fixed side portion 3 has a lower die 30 and a lower die holder 32 that fixes 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 with bolts 34. The lower die 30 also has a hole 31 that has a shape corresponding to the shape of the punch 10, and a hole 33 that receives the guide pin 27. The press working device 1 also has a drive mechanism (not shown) for applying the force required for working to the die, a control mechanism (not shown) for controlling this, a safety device (not shown), etc.

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

[0010] FIG. 3 shows the structure (plan and side) of a punch 10 having a rectangular cross section, and a cross-sectional view of the engagement between the holding portion 11 of the punch 10 and the punch plate 21A and back plate 21B of the upper die. The holding portion 11 is provided in a flange-like shape on the outer surface (two sides) of the punch 10 at the midpoint. That is, FIG. 3(A) is a plan view of the punch 10, and the connecting portion 20A of the vibrator 20 is provided as a screw hole at the top of the punch on the centerline, and the connecting surfaces of the vibrator 20 and the punch 10 are crimped together. For example, by applying pressure to the connecting surface, such as by axial force of a screw or press-fitting, and maintaining the surface pressure, the vibration of the vibrator 20 is transmitted to the punch 10 in a stable and efficient manner. FIG. 3(B) is a side view, and FIG. 3(C) is a cross-sectional view showing how the holding portion 11 is gripped and held by the punch plate 21A and back plate 21B.

[0011] 4A and 4B show an example of a punch 10A having a circular cross section, with Fig. 4A being a perspective view and Fig. 4B being a side view in the Y direction. The punch 10A in this example has a circular horizontal cross section, a flange-shaped retaining portion 11A is provided around the periphery of the punch 10A at the middle of the side surface, and a through hole 13 is drilled laterally by cutting out a portion of the retaining portion 11A, with the through hole 13 being a single hole distributed in the vertical direction 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 the press working is selected depending on the type of work and the workpiece W, and the workpiece W placed on the upper surface of the lower die 30 is subjected to separation processing and the like by the reciprocating motion of the punch 10 (or 10A) caused by the drive mechanism and the up and down vibration of the vibrator 20. At this time, the processing quality is improved by the resonance action based on the through-hole 12 (13) drilled in the punch 10 (10A).

[0013] However, in conventional punches, a portion of the holding portion is notched to accommodate the through-hole, which reduces the strength of the punch. Furthermore, the presence of a notch in the holding portion makes it difficult to provide a D-cut for preventing rotation or positioning, particularly in cylindrical punches. Furthermore, the through-hole drilled through the holding portion expands and contracts vertically and horizontally due to vibration, causing the holding portion to move horizontally (perpendicular to the center line). This causes friction loss between the holding portion and the punch plate and between the holding portion and the back plate, resulting in a deterioration in the effectiveness of vibration transmission.

[0014] In conventional punches, the through-hole for reducing rigidity simultaneously cuts out a portion of the holding portion for fixation. Because the notch is located approximately in the center of the through-hole, the through-hole expands and contracts vertically and horizontally in response to vertical vibration. As a result, the holding portion 11, which is used for fixation, moves perpendicular to the vibration, as shown in the displacement distribution diagram in Figure 5. Depending on the degree of vibration, the punch may not move or may move easily, depending on whether the gripping force is firm or weak. Depending on the degree of vibration, the punch's resonance point fluctuates, as described below, and the lateral amplitude is large. This, combined with the gripping force, generates friction and heat, resulting in fluctuations in vibration energy loss. Furthermore, the resonance point and lateral amplitude change over time due to wear of the components caused by friction and 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 in the case of a conventional punch that does not have a notch in the holding portion, the same problem occurs because the punch undergoes large lateral vibrations.

[0016] The punch shown in Patent Document 1 is based on the premise that it is symmetrical up and down with respect to the holding part, and the resonance point of the entire punch is aligned with the through-hole (long hole) that promotes deformation in the horizontal direction (deformation equivalent to Poisson's ratio) due to vertical vibration, so this does not work with punches that are highly asymmetric.

[0017] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a press working punch and a press working apparatus equipped with the same, which can easily adjust the resonance point without weakening the punch strength, regardless of the shape or material, and regardless of vertical symmetry, thereby improving the punch function and the quality of press working. In the press working punch of the present invention, the rigidity and weight (mass) can be adjusted above and below the position of the holding part, which serves as a node, so that it can be used not only for vertical symmetry but also for strong asymmetric shapes.

[0018] The present invention relates to a punch that is attached to an upper die of a press working apparatus and is driven by a vibrator, and the above-mentioned object of the present invention is achieved by a press working apparatus that includes the press working punch and in which the vibrator is disposed at the top of the punch on the centerline, the cross-sectional shape of the punch in a horizontal plane perpendicular to a vertical plane including a centerline in the punch direction has a structure that is plane-symmetrical with respect to the vertical plane, the punch is provided with a flange-shaped holding portion on the outer peripheral edge or side of a midpoint in the punch direction, a first through-hole is formed in an upper punch body above the holding portion, and a second through-hole is formed in a lower punch body below the holding portion.

[0019] The present invention relates to a punch to be attached to the upper die of a press working apparatus, and the above-mentioned object of the present invention is achieved by a punch having a circular cross section, which has a flange-shaped retaining portion formed around the outer periphery of the middle part of the punch without any notch, and an upper punch body above the retaining portion having a first through hole and a lower punch body below the retaining portion, and by the resonance action of the first through hole, the second through hole, the upper punch body, and the lower punch body, with respect to up-and-down vibrations applied to the top of the punch, the position of the retaining portion becomes a node of vibration displacement, and the top of the upper punch body and the bottom of the lower punch body become antinodes of the vibration displacement, and also by a press working apparatus which is provided with this press working punch and has a vibrator disposed at the top of the punch.

[0020] The present invention also relates to a punch to be attached to the upper die of a press working apparatus, and the above-mentioned object of the present invention is achieved by providing holding parts without flange-shaped notches on the outer surfaces of the midway part of a punch having a rectangular cross section, and by providing a first through hole in an upper punch body above the holding parts and a second through hole in a lower punch body below the holding parts, and by resonating the first through hole, the second through hole, and the upper and lower punch bodies, the position of the holding parts becomes a node of vibration displacement with respect to up-and-down 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, and the above-mentioned object is achieved by a press working apparatus provided with this press working punch and having a vibrator disposed at the top of the punch.

[0021] Furthermore, the present invention relates to a punch which is mounted on the upper die of a press working apparatus and is driven by a vibrator, and the above-mentioned object of the present invention is achieved in that the cross-sectional shape of the punch in a horizontal plane perpendicular to a vertical plane containing the centerline in the punch direction is shaped like a barrel drum and is plane-symmetrical with respect to the vertical plane, brim-shaped retaining portions are provided facing each other on the outer surfaces of a midsection of the punch, a first through-hole is formed in the upper punch body above the retaining portions, and a second through-hole is formed in the lower punch body below the retaining portions, and the first through-hole, the second through-hole, and the upper and lower punch bodies resonate to apply up and down vibrations to the center of the top of the punch, with the positions of the retaining portions becoming nodes of vibration displacement and the top of the upper punch body and the bottom of the lower punch body becoming antinodes of the vibration displacement.

[0022] In the press working punch of the present invention, the cross-sectional shape of the punch in a horizontal plane perpendicular to a vertical plane containing the centerline of the punch is plane-symmetrical with respect to the vertical plane. This reduces lateral deformation due to vertical vibration of the retaining portion provided on the outer periphery or outer surface, reduces wear and friction losses of the gripping retaining portion, and reduces changes in vibration characteristics due to gripping force. Furthermore, since notches are not required in the retaining portion provided on the outer periphery or outer surface, the punch can be firmly held and fixed without reducing strength. Furthermore, in this invention, through holes are provided in the upper and lower punch bodies of the retaining portion. Although the punch body is made of steel, the weight is increased by the cutting blade at the tip, allowing for active adjustment of the weight distribution, thereby allowing for adjustment of only the lower punch body. In this way, the vibrator side and the punch tip side can be adjusted independently, making it easy to align the resonance points of the vibrator side and the punch tip side. Therefore, vibration transmission is possible even when the retaining portion is firmly fixed.

[0023] One factor that contributes to the asymmetry between the top and bottom is the grinding of worn or chipped edges at the punch edge during punch maintenance to keep them sharp (angled). After several maintenance sessions, the blade may be ground by 10 mm or more from its original state, further contributing to the asymmetry between the top and bottom of the holder. In such cases, the frequency at the tip of the punch increases, and the rigidity at the tip of the punch decreases. However, according to the present invention, this can be easily corrected by enlarging the through hole. In particular, when only the tip is made of super steel, the body is also made of steel, making it easy to enlarge the through hole.

[0024] FIG. 1 is a configuration diagram showing an example of a general press working device; FIG. 2 is a perspective view and a side view showing an example of a punch; FIG. 3 is a plan view, a front view, and a sectional structural view showing an example of a punch and a holding example; FIG. 4 is a perspective view and a side view showing another example of a punch; FIG. 5 is a displacement distribution diagram showing example characteristics (two examples) of a conventional punch; FIG. 6 is a front view and a side view showing an example of a punch according to the present invention; FIG. 7 is a side view and a characteristic diagram of a mechanism for explaining the principle of the present invention; FIG. 8 is a structural diagram (plan view and side view) for explaining a comparison between the present invention and a conventional example; FIG. 9 is a characteristic diagram showing the effects (presence or absence of a through hole) of the present invention and a conventional example; FIG. 10 is a characteristic diagram showing the effects (longitudinal displacement) of the present invention and a conventional example; FIG. 11 is a characteristic diagram showing the effects (gripping force) of the present invention and a conventional example; FIG. 12 is a characteristic diagram showing the effects (lateral amplitude) of the present invention and a conventional example; FIG. 13 is a characteristic diagram explaining the effects (displacement and lateral amplitude) of the present invention; FIG. 14 is a perspective view and a side view showing another example of a punch according to the present invention; FIG. 15 is a front view showing another example of a punch according to the present invention; FIG. 16 is a plan sectional view showing another example of a through hole provided in a punch according to the present invention; FIG. 17 is a front view showing another example of a punch to which the present invention can be applied; FIG. 18 is a plan view showing an example of attachment of a holding portion in a punch having a rectangular cross section; FIG. 1 is a perspective view and a plan view showing an example of a punch having a barrel-drum-shaped cross section; FIG. 2 is a perspective view and a plan view showing another example of a punch having a barrel-drum-shaped cross section; FIG. 3 is a cross-sectional view and a plan view showing an example of a punch having a skewer-shaped cross section; FIG. 4 is a cross-sectional view and a plan view showing an example of a punch having a double-ended trumpet-shaped cross section; FIG. 5 is a cross-sectional view and a plan view showing an example of a punch having a barbell-shaped cross section; FIG. 6 is a cross-sectional view and a plan view showing an example of a punch having a tsutsumi-drum-shaped cross section.

[0025] Conventional punches are based on the premise of homogeneous punch material and equal wavelengths, and are considered desirable to be vertically symmetrical with respect to a holder provided on the periphery or outer surface of the punch. However, this is not always the case depending on the type of press working. The present invention improves performance even for punches with strong vertical asymmetry by independently adjusting the rigidity and weight distributions on the vibrator side and the punch tip side, separated by the holder, to match the resonance points (the highest vibration frequencies) on the vibrator side and the punch tip side. Furthermore, the punch according to the present invention has a cross-sectional shape in a horizontal plane perpendicular to a vertical plane including the centerline in the punch direction (vertical direction) that is plane-symmetrical with respect to the vertical plane, and the vibrator is arranged on the centerline when mounted in a press working device.

[0026] That is, in the present invention, as shown in Fig. 6, a flange-shaped retaining portion 101 (thickness D) is provided around the outer periphery of the punch 100 midway in the punching direction (vertical direction) without any notches, and a through-hole 110 having a rectangular cross section is bored in the upper punch body (oscillator side) of the punch 100 above the retaining portion 101, and a through-hole 111 having a rectangular cross section is bored in the lower punch body (punch tip side) of the punch 100. The stiffness and weight (mass) of the punch body are adjusted so that, due to the resonance of the through-holes 110, 111 and the punch body, the position of the retaining portion 101 becomes a node of displacement (vibration) (displacement = 0) and the top of the upper punch body and the bottom of the lower punch body become antinodes of displacement (vibration) (displacement = maximum) for up-and-down vibration (simple harmonic motion) caused by the oscillator applied to the top of the punch 100 as shown in Fig. 7(A) . The adjustment of stiffness and weight is performed by adjusting the size of the through-holes 110 and 111. In this example, the through holes 110 and 111 are drilled parallel to each other through the center line. As shown in FIG. 7B, near the top of the node (region AR), the displacement increases sharply from 0 mm, reducing the cross-sectional area of ​​the portion acting as a spring. The same is true for 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, and also reduces the actual spring stiffness, increasing the amplitude.

[0027] The positional relationship between the retaining portion 101 and the through holes 110, 111 is such that the top surface of the retaining portion 101 and the bottom surface of the through hole 110 are close to each other (including contact or partial cut-off), and the retaining portion 101 and the top of the through hole 111 are close to each other (including contact or partial cut-off). The cross-sectional shape of the through holes 110 and 111 may be circular, elliptical, rectangular, etc., but any cross-sectional shape is acceptable as long as the following condition is satisfied. 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] Generally, vibrations tend to lower the resonance point by increasing the weight of the antinode, and lowering the spring stiffness also lowers the resonance point. In a press punch, the antinode of vibration is the end (the tip of the punch and the vibrator mounting surface), and the fixed end is the node support. The stiffness of a spring from the support to the end corresponds to the spring constant. Vibration is also a sine curve, with the displacement increasing steeply from zero displacement, i.e., the node, and transitioning to a more gradual displacement at the antinode end where it reaches 90°. This abrupt displacement portion contributes significantly to the spring, and reducing the stiffness of this portion tends to lower the resonance point. The through-holes 110 and 111 near the node reduce the stiffness of the portion that contributes to the spring, significantly contributing to lowering the resonance point. The size of the through-holes 110 and 111 also allows for weight adjustment, so the following combinations can be envisioned depending on the shape of the punch 100. The vicinity of the holding portion 101, which has a strong tendency to act as a spring, tends to have a higher sensitivity to adjusting the spring constant k, and the through holes 110, 111 close to the holding portion 101 tend to be more effective in lowering the resonance point.

[0029] In the present invention, the holding portion 101, which is provided around the outer periphery of the punch 100 or facing the outer surface, does not have any notches, thereby maintaining the necessary rigidity and strength of the punch 100. Even for a punch with a shape that is highly asymmetric in the vertical direction across the holding portion 101, the resonance effect can be further enhanced by independently adjusting the through holes 110 and 111. That is, the resonance effect can be enhanced by aligning the resonance point on the vibrator side, which is formed by the through hole 110, with the resonance point on the punch tip side, which is formed by the through hole 111. The holding portion 101 is a vibration node and does not have a vibration adjustment function. Since the holding portion 101 is not notched, its function as positioning and holding is the same as that of the conventional punch plate 21A and back plate 21B, as shown in FIG. 3(C). However, even without notches in the holding portion 101, the positioning and holding functions are not impaired and the vibration characteristics can be adjusted. This solves the conventional problem of the through hole cut out of part of the holding part mentioned above, and can be incorporated between the punch plate 21A and the back plate 21B while maintaining strength and rigidity, and the D-cut for positioning can also be easily processed.

[0030] Next, we will explain how to align the resonance points between the oscillator-side section of the upper punch and the punch tip-side section of the lower punch. The punch oscillator and punch tip have different requirements due to the characteristics of their mechanisms. For example, the oscillator side needs to be short to keep the overall height of the die low. However, simply shortening it increases rigidity but reduces weight, both of which tend to raise the resonance point. On the other hand, the punch tip needs to maintain a certain length to function as a stripper, punch plate, and press stroke, which tends to lower the resonance point compared to the oscillator side. Comprehensive measures are needed to address these tradeoffs. In the case of a super-steel punch with a steel punch body and a super-steel punch at the tip, which is subject to high wear, or a punch for simultaneous two-hole punching with two cutting blades at the tip, the rigidity of the punch and weight increase, which also lowers the resonance point. Therefore, it is important to easily accommodate these systems.

[0031] In the punch 100 of a press working device, as shown in FIGS. 7A and 7B , it is desirable to realize vibration with the holding portion 101, which is sandwiched between the punch plate and back plate as the fixed point, as the node (displacement = 0), and the punch tip (top and bottom) as the antinode (maximum displacement). This is because the vibration of the oscillator located above the punch is largely transmitted to the punch tip. The length from the holding portion 101 to the punch tip is not only required to fit the entire die height within the die height of the press working device, but also to be appropriate based on the die processing equipment, precision, and functionality. Dies used for low SPM (shots per minute) applications can be made longer, and in such cases, punches made of ferrous materials are often used. These ferrous punches have a long overall length and a lower Young's modulus than cemented carbide, making it easy to align the antinode of the amplitude with the punch tip. However, dies used in high-speed presses, especially those punching electromagnetic steel sheets, tend to be shorter, and cemented carbide is often used as the punch material. Although this super steel punch is heavier, its Young's modulus is higher. This, combined with its short length, shifts the resonance frequency to the higher frequency side, making it difficult to align the antinode with the punch tip. Specifically, to efficiently transmit a vibration frequency of approximately 10 to 30 kHz from the vibrator to the punch tip, the entire punch must resonate without attenuating the set frequency. The holding portion 101 serves as a vibration node. As shown in Figure 6(B), when the length of the punch tip side is L1 and the length of the vibrator side is L2, the length L1 of the punch tip side is determined by the die structure and the material used. At the same time, the length L2 of the vibrator side is also subject to different constraints depending on the die structure and the press equipment used, so that the lengths L1 and L2 are not equal. Therefore, the rigidity and resonant frequency (wavelength) differ across the holding portion 101. Therefore, unless the cross-sectional shape of the punch body is changed at lengths L1 and L2 and the rigidity is adjusted, resonance with the tip as the antinode cannot be achieved.

[0032] Based on these assumptions, a method for adjusting the resonant frequency will be described. As described above, the lengths L1 and L2 are different, and the length L1 is strongly restricted by the mold structure and application. Therefore, based on this premise, resonance with an oscillation frequency with the holding portion 101 as a node must be achieved. Therefore, the rigidity and weight of the punch 100 are adjusted by adjusting the cross-sectional shape of the length L1 on the punch tip side and the length L2 on the punch vibrator side. The holding portion 101 is not notched to obtain rigidity that serves as a vibration node, but rather the rigidity and weight distribution on both the upper and lower sides of the holding portion 101 are adjusted. By adjusting the rigidity and weight in this manner, the resonant frequencies on the vibrator side and the punch tip side can be adjusted. In the present invention, the 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 portion 101, and the weight is also adjusted by increasing the area of ​​the cross-sectional shape. This adjusted cross-sectional shape is also effective for adjusting the longitudinal dimension in the axial direction. Therefore, the following adjustment requirements (1) to (3) are met. (1) In a tool horn with different lengths L1 and L2, the rigidity and weight are adjusted at different cross sections at each of the lengths L1 and L2. (2) When adjusting the cross-sectional area for reducing rigidity, the through-hole is close to the surface of the holder (the closer the better, and a contacting state is best). (3) When adjusting the weight distribution gradient (especially reduction), the through-hole is close to the surface of the holder (the closer the better, and a contacting state is best).

[0033] 6, in the present invention, a holding portion 101 without a notch is provided around the periphery of the middle portion of a punch 100 having a circular cross section, and a through-hole 110 having a substantially rectangular cross section is provided in the punch body above the top surface of the holding portion 101, and a through-hole 111 having a substantially rectangular cross section is provided in the punch body below the bottom surface of the holding portion 101. That is, the upper and lower punch bodies are provided with separate through-holes 110 and 111 that are arranged parallel to each other and pass through the center line, close to the holding portion 101. The thickness of the holding portion 101 is D, the length from the bottom surface of the punch 100 to the bottom surface of the holding portion 101 (the length on the punch tip side) is L1, and the length from the top surface of the punch 100 to the top surface of the holding portion 101 (the length on the punch oscillator side) is L2.

[0034] The sizes (diameters) and shapes of the through holes 110 and 111 are adjusted according to the specifications described above, and are punched in the upper and lower punch bodies, respectively. Specifically, Figures 8(A1) to 8(C2) show a plan view (A1) and a front view (A2) of a punch having a rectangular cross section, with a holding portion but without a through hole; a plan view (B1) and a front view (B2) of a punch having the holding portion 101 of the present invention shown in Figure 6, with the through holes 110 and 111, but without a notch in the holding portion 101, and with the through holes 110 and 111 separated from each other; and a plan view (C1) and a front view (C2) of a conventional example, in which the holding portion 11 has a notch and the through hole 12 penetrates from top to bottom. In all cases, a 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 FIG. 8(B1), while in the conventional example, simple harmonic motion is applied from the vibrator mounting surface 20A shown in FIG. 8(C1).

[0035] 9 to 12 correspond to the punch structures shown in Figures 8(A) to 8(C), i.e., an example of a punch without a through hole (Figure 8(A)), an example of a punch of the present invention (Figure 8(B)), and an example of a punch of the prior art (Patent Document 1) (Figure 8(C)), and show a comparison of the characteristics of each punch for each item. Note that 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. Without through-holes, adjustment is not possible, and the target frequency band is therefore difficult to achieve. Regarding the target frequency band, it is desirable to select the frequency from a set of vibrators and oscillators from a ready-made product (a catalog product that has been approved and registered and is sold by the manufacturer). Because the basic shape (the original shape without through-holes) has the highest rigidity, raising the resonant frequency is extremely difficult, and the only way to achieve this is to lower the resonance point. Since a single die (pressing machine) requires dozens of different punches, maintaining a reusable vibrator and oscillator set with the same specifications offers the advantage of avoiding misassembly and misconnection, minimizing costs, response time, and labor costs in terms of damage response and equipment inventory. Furthermore, since the manufacturer's ready-made vibrator and oscillator sets are already certified, using a non-certified set requires the time and effort required for approval, which increases costs and extends the die production schedule. However, off-the-shelf products avoid these problems and offer the added benefit of manufacturer warranties on resonators and oscillator sets, as well as the availability of spare parts in stock in case of breakdowns or support. For example, a resonator manufacturer, Company A, offers a lineup of products at 15.15 kHz, 19.15 kHz, 28.5 kHz, and 39.5 kHz, meaning no intermediate frequencies other than these can be used. Meanwhile, another manufacturer, Company B, offers a lineup of products at 15 kHz, 20 kHz, 27 kHz, 28 kHz, 30 kHz, 39 kHz, 40 kHz, and 60 kHz, meaning no intermediate frequencies other than these can be used. The same is true for other resonator manufacturers. Because there are no unified standards for resonators, there is no compatibility between manufacturers, and the dimensions, operation methods, and peripheral devices vary. For this reason, in practice, it is necessary to select one manufacturer and operate within the scope of their lineup.

[0037] On the other hand, customizing the vibrator and oscillator to match the punch shape and material requires special specifications, which require individual design, manufacturing, and approval, resulting in significant cost and schedule disadvantages. 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 this is not possible. Regarding the target frequency, punches vary in shape and material depending on the shape of the workpiece and the pressing process, resulting in different vibration characteristics. However, with the punch of the present invention, the resonant frequency can be easily adjusted by drilling upper and lower through-holes, so the target frequency can be optimized to match 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 is about 0.003 mm larger than the conventional punch. A larger amplitude at the punch tip means a larger vibration effect, which improves press forming performance. In contrast, when there is no through hole, the amplitude is also small, and it can be seen that the vibration effect is significantly smaller than with the conventional punch.

[0039] Figure 11 compares the resonant frequency of the punch of the present invention with that of the conventional punch, comparing the difference in gripping force between the punch plate 21A and the back plate 21B. A strong gripping force firmly holds the punch 100 via the retaining portion 101, resulting in small lateral displacement. A weak gripping force increases lateral displacement, resulting in a lower resonant frequency. That is, a weak gripping force results in a 0.10 kHz drop in the case of the punch without a through-hole, a 0.15 kHz drop in the case of the punch of the present invention, and a 0.28 kHz drop in the case of the conventional punch. The punch of the present invention achieves a 46% reduction in fluctuation compared to the conventional punch. Even with a weak gripping force, the resonant frequency of the punch of the present invention remains within the target frequency band, even with a 0.15 kHz drop. However, with a weak gripping force, the resonant frequency of the conventional punch drops by 0.28 kHz, resulting in a drop outside the target frequency band. Without a through-hole, the resonant frequency remains outside the target frequency band regardless of whether the gripping force is strong or weak.

[0040] Fig. 12 summarizes the displacements in Fig. 5 and Fig. 13, and Fig. 13 shows the displacement distribution when the punch of the present invention is not gripping, with a lateral amplitude of 0.002 mm. Fig. 12 also shows a comparison of the lateral amplitudes of each specification, with the lateral amplitude of the punch of the present invention being 0.002 mm, an 80% reduction compared to 0.01 mm for the conventional punch, indicating a significant improvement in lateral amplitude.

[0041] 14 shows another embodiment of the present invention, in which the through-holes 110 and 111 are cut on the side of the holding portion 101, and the upper and lower surfaces of the holding portion 101 form part of the through-holes 110 and 111. In view of the adjustment requirements (2) and (3), the through-hole configuration of FIG. 14 is the most desirable. In this way, 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] 15(A) and 15(B) show an example in which the through holes 112 and 113 have different sizes and shapes as a result of adjusting the nodes and antinodes of the resonant frequency as described above. Similarly, FIG. 15(B) shows an example in which the through holes 114 and 115 have different sizes and shapes. That is, because both upper punch bodies are long and large, the upper through holes 112 and 114 are larger than the lower through holes 113 and 115, respectively. In the example of FIG. 15(A), the cross section of the through hole 112 is elliptical and the cross section of the through hole 113 is circular. In the example of FIG. 15(B), the cross sections of the through holes 114 and 115 are both elliptical. Note that if the asymmetry between the top and bottom is extremely pronounced, one of the smaller through holes may be size 0.

[0043] Furthermore, in each of the above-described examples, 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, as shown in FIG. 16, for example.

[0044] In press punches, two punching blades 126A and 126B are provided at the tip of the punch 120 for simultaneous punching of two holes from a single punch material, as shown in FIG. 17(A). This type of punch 120 is asymmetrical in shape, weight, and rigidity. The overall length of the punch is short due to its mold structure, which unintentionally increases the resonance point, making it necessary to lower the resonance point. The distance from the holder 121 to the punch tip remains unchanged, but the weight of the tip decreases, resulting in a higher frequency. Therefore, the rigidity of the tip side is reduced while maintaining the weight. To lower the frequency on the vibrator side and make it equivalent to the tip side, the rigidity near the holder 121 is reduced while maintaining the end weight, thereby tuning the resonance point. In FIG. 17(A), area 122 is the weight portion on the vibrator side with small deformation, and area 125 is the weight portion on the punch tip side with small deformation, both of which serve as weight adjustment areas. Further, range 123 is a spring portion that is largely deformed on the vibrator side, and range 124 is a spring portion that is largely deformed on the punch tip side, both of which serve as rigidity adjustment portions.

[0045] In addition, in the case of punches for press working, there are some punches as shown in Figure 17(B) in which a cutting blade 134 made of super steel material is attached to the tip of the punch 130 in order to increase the life of the cutting blade and the amplitude of vibration, and the punch is asymmetrical in terms of material, weight, and rigidity. The body of the punch 130 is made of steel and has a density of 7720 kg / m 3 , Young's modulus is 2.10E+11, while the density of super steel is 14050kg / m 3 , and Young's modulus of 5.20E+11, resulting in strong asymmetry. In this example, the overall length of the punch is short due to the die structure, so it is necessary to lower the resonance point. The distance from the holder 131 to the punch tip remains the same, and since the tip weight is heavy, there is little adjustment of rigidity on the tip side (the diameter of the through-hole 133B is small). However, since there is a distance from the holder 131 to the top on the vibrator side, both the weight and rigidity are reduced (the diameter of the through-hole 132A is large), and the resonance point is tuned.

[0046] 17(B), when the punch body is made of steel and the tip is made of ultra-hard steel with a high Young's modulus and mass density, the asymmetry between the top and bottom is significantly lost, but in such a case, a through hole is drilled only on the vibrator side to lower the resonance point. In other words, the lower through hole 133B does not have to be provided.

[0047] Although the above examples have mainly been described with respect to punches having a circular horizontal cross section, a punch having a rectangular cross section may also be used, as shown in Fig. 18 . That is, the example of Fig. 18(A) shows a case in which non-notched retaining portions 141A and 141B are provided facing each other on the outer surface of the punch 140 so as to be perpendicular to the through holes 142 and 143. The example of Fig. 18(B) shows a case in which non-notched retaining portions 141C and 141D are provided facing 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 of Fig. 18(C) shows a case in which non-notched retaining portions 141A and 141B are provided facing 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 facing 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 effect as described above can be obtained by drilling the through holes 142 and 143.

[0048] In FIGS. 18A to 18C, the reference numeral 140A denotes the mounting portion of the vibrator, and in all cases the vibrator is arranged on the center line CL.

[0049] 19 and 20 show an example of a punch 150 having a barrel-drum-shaped cross section. Specifically, Fig. 19(A) shows an oblique view of an example in which two parallel through-holes 152 and 153, one above the other, are provided in a direction perpendicular to a holding portion 151 provided on opposing outer surfaces, and Fig. 19(B) shows a plan view. Also, Fig. 20(A) shows an oblique view of an example in which two parallel through-holes 152 and 153, one above the other, are provided in parallel with the holding portion 151, and Fig. 20(B) shows a plan view. Even with a punch having such a barrel-drum-shaped cross section, the same effects as those described above can be obtained.

[0050] In Figures 19 and 20, the symbol 150A indicates the mounting portion of the vibrator, and in both cases the vibrator is arranged on the center line CL and is plane-symmetrical with respect to a plane including the center line CL.

[0051] The press processing punch according to the present invention has a cross-sectional shape in a horizontal plane perpendicular to a vertical plane including a center line CL in the punch direction, which has a structure that is plane-symmetrical with respect to the vertical plane, and when mounted on a press processing device, the vibrator is disposed at the apex on the center line CL. However, the punch structure according to the present invention may have a cross-sectional shape such as that described below, in addition to the circular, rectangular, and barrel-drum-shaped cross sections described above.

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

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

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

[0055] 24 shows a cross-sectional view of a punch 190 having a cross-section shaped like a drum, with holding portions 191 provided at both ends and a vibrator disposed on a center line CL. This punch 190 may be provided with a through-hole 192 that passes through the center line CL and is parallel to the holding portion 191, as shown in FIG. 24(A), or may be provided with a through-hole 193 that passes through the center line CL and is perpendicular to the holding portion 191, as shown in FIG. 24(B).

[0056] REFERENCE SIGNS LIST 1 Press processing device 2 Movable side part (upper die) 3 Fixed side part 10, 10A Punch 11, 11A Holding part 12, 13 Through hole 20 Vibrator 20A Connection part 21A Punch plate 21B Back plate 22 Upper die holder 23 Support 24A, 24B, 34 Bolt 25 Stripper 26 Spring 27 Guide pin 30 Lower die 31, 33 Hole 32 Lower die holder 100 Punch 101 Holding part 110, 111 Through hole 112, 113, 114, 115 Through hole 120, 130, 140, 150 Punch 160, 170, 180, 190 Punch 126A, 126B, 134 Cutting blade

Claims

1. A punch that is mounted on the upper die of a press working apparatus and is driven by a vibrator, wherein a cross-sectional shape of the punch in a horizontal plane perpendicular to a vertical plane including a center line in the punch direction has a structure that is symmetric with respect to the vertical plane, a flange-shaped holding portion is provided on an outer peripheral edge or a side surface of a middle portion of the punch in the punch direction, a first through hole is formed in an upper punch body above the holding portion, and a second through hole is formed in a lower punch body below the holding portion. A punch for press working, characterized in that.

2. The punch for press working according to claim 1, wherein each hole cross-section of the first through hole and the second through hole is circular, elliptical, or rectangular.

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

4. A press working apparatus comprising the punch for press working according to claim 1, wherein the vibrator is disposed at a top of the punch on the center line.

5. A flange-shaped holding portion is provided around an outer peripheral edge of a middle portion of a punch having a circular cross-section, which is mounted on the upper die of a press working apparatus. A first through hole is formed in an upper punch body above the holding portion, and a second through hole is formed in a lower punch body below the holding portion. Due to a resonance action of the first through hole, the second through hole, the upper punch body, and the lower punch body, with respect to vertical vibration applied to the top of the punch, a position of the holding portion becomes a node of vibration displacement, and a top of the upper punch body and a bottom of the lower punch body each become an antinode of the vibration displacement. A punch for press working, characterized in that.

6. The punch for press working according to claim 5, wherein no notch is provided in the holding portion.

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

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

9. The punch for press working according to claim 5 or 6, wherein each hole cross-section of the first through hole and the second through hole is circular, elliptical, or rectangular.

10. A press working apparatus comprising the punch for press working according to claim 5, wherein a vibrator is disposed at the top of the punch.

11. A punch for press working is mounted on the upper die of a press working apparatus. A flange-shaped holding portion is provided opposite to the outer surface of the middle portion of the punch having a rectangular cross-section. A first through hole is formed in the upper punch body above the holding portion, and a second through hole is formed in the lower punch body below the holding portion. Due to the resonance effect of the first through hole, the second through hole, the upper punch body, and the lower punch body, with respect to the vertical vibration applied to the top of the punch, the position of the holding portion becomes a node of vibration displacement, and the top of the upper punch body and the bottom of the lower punch body respectively become the antinodes of the vibration displacement.

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

13. The punch for press working according to claim 11, wherein the first through hole and the second through hole are provided non-parallelly, 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 punch for press working according to any one of claims 11 to 13, wherein each hole cross-section of the first through hole and the second through hole is circular, elliptical, or rectangular.

15. A press working apparatus comprising the punch for press working according to claim 7, wherein a vibrator is disposed at the top of the punch.

16. A punch that is mounted on the upper die of a press working device and is driven by a vibrator, wherein a cross-sectional shape of the punch in a horizontal plane orthogonal to a vertical plane including a center line in the punch direction is a barrel drum shape that is plane-symmetrical with respect to the vertical plane, a flange-shaped holding portion is provided opposite to an outer surface of a middle portion of the punch, a first through hole is formed in an upper punch body on an upper side of the holding portion, a second through hole is formed in a lower punch body on a lower side of the holding portion, and due to a resonance action of the first through hole, the second through hole, the upper punch body, and the lower punch body, with respect to vertical vibration applied to a top portion of the punch on the center line, a position of the holding portion becomes a node of vibration displacement, and a top portion of the upper punch body and a bottom portion of the lower punch body respectively become bellies of the vibration displacement. A punch for press working characterized by this.

17. The punch for press working according to claim 16, wherein each hole cross-section of the first through hole and the second through hole is circular, or elliptical, or rectangular.

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