Cam mechanism and its design method
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SANKYO OILLESS IND
- Filing Date
- 2025-12-25
- Publication Date
- 2026-08-05
AI Technical Summary
【0012】 本発明によれば、高加工力下において加工精度を確保できるカム装置を提供することができる。
Smart Images
Figure 0007900865000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a cam device and a design method thereof.
Background Art
[0002] Weight reduction is a common issue for both reciprocating engines and electric vehicles (EVs), and in fact, weight reduction in EVs contributes more significantly than in reciprocating engines. Therefore, automotive steel sheets are common to all vehicles for improving fuel efficiency, and the trend is towards thinner high-strength sheets.
[0003] Automotive steel sheets mainly involve the processing of relatively easy-to-process steel sheets. Therefore, in the cam devices for press processing of automotive steel sheets, the response to high-tensile materials is insufficient, and sufficient consideration has not been given to the design requirements regarding the required processing accuracy and wear resistance.
[0004] Patent Document 1 discloses a cam device that achieves both maintainability and maintenance of processing accuracy by configuring the sliding member of the cam slider to be detachable, enabling parts to be replaced unit by unit without replacing the entire slider when wear or damage occurs.
[0005] Patent Document 2 discloses a configuration in which the wear amount at the sliding portion between the cam holder and the cam slider is intentionally set larger than that between the cam driver and the cam slider, thereby eliminating the initial single contact at an early stage and stabilizing the positional accuracy of the processing tool.
Prior Art Documents
Patent Documents
[0006]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0007] However, both Patent Documents 1 and 2 are based on the assumption of processing general steel plates, and it is difficult to ensure stable processing accuracy when processing difficult-to-process materials that require high processing force, such as high-tensile steel.
[0008] In automotive press working, the demand for processing high-tensile steel is increasing, and the high loads during the forming process are causing increased wear on the sliding components of the cams used in the molds, which is becoming a problem.
[0009] This invention was made to solve the aforementioned conventional problems, and aims to provide a cam device that can ensure machining accuracy under high machining forces. [Means for solving the problem]
[0010] The present invention relates to a cam device comprising: a cam holder having a cam holder sliding surface; a cam slider having a first sliding surface and a second sliding surface that slides against the cam holder sliding surface; and a cam driver having a cam driver sliding surface that abuts against the second sliding surface and drives the cam slider in a predetermined machining direction, wherein Q is the component force perpendicular to the cam holder sliding surface applied to the cam holder sliding surface, V is the component force perpendicular to the cam driver sliding surface applied to the cam driver sliding surface, Sh is the sliding surface area of the cam holder sliding surface, Sd is the sliding surface area of the cam driver sliding surface, Gh (%) is the graphite embedding rate of the sliding surface area Sh of the cam holder sliding surface, and Gd (%) is the graphite embedding rate of the sliding surface area Sd of the cam driver sliding surface, and the surface pressure (V / Sd) generated on the cam driver sliding surface is relative to the surface pressure (Q / Sh(1-Gh / 100)) generated on the cam holder sliding surface. This cam device is characterized by having the following surface pressure ratio between the cam holder and cam driver, which is the ratio of cosθ(1-Gd / 100): 1.0 ≤ (Q / Sh(1-Gh / 100)) / (V / Sd·cosθ(1-Gd / 100)) ≤ 3.0)
[0011] The present invention relates to a cam holder having a cam holder sliding surface, and a first sliding surface of a cam slider that slides against the cam holder sliding surface, The cam driver slides against the sliding surface. Cam slider second sliding surface of Yes Cam slider andA design method for a cam device having a cam driver having a cam driver sliding surface that contacts the second sliding surface of a cam slider and drives the cam slider in a predetermined machining direction, wherein Q is the component force perpendicular to the cam holder sliding surface applied to the cam holder sliding surface, V is the component force perpendicular to the cam driver sliding surface applied to the cam driver sliding surface, Sh is the sliding surface area of the cam holder sliding surface, Sd is the sliding surface area of the cam driver sliding surface, Gh (%) is the graphite embedding rate of the sliding surface area Sh of the cam holder sliding surface, Gd (%) is the graphite embedding rate of the sliding surface area Sd of the cam driver sliding surface, and the cam holder-cam driver surface pressure ratio, which is the ratio of the surface pressure (V / Sd · cosθ(1-Gd / 100)) generated on the cam driver sliding surface to the surface pressure (Q / Sh(1-Gh / 100)) generated on the cam holder sliding surface, is as follows. 1.0≦(Q / Sh(1-Gh / 100)) / (V / Sd·cosθ(1-Gd / 100))≦3.0. [Effects of the Invention]
[0012] According to the present invention, it is possible to provide a cam device that can ensure machining accuracy under high machining force. [Brief explanation of the drawing]
[0013] [Figure 1] This is an exploded view of the cam mechanism of the embodiment. [Figure 2] This is a schematic diagram of a cam mechanism mounted on a press die. [Figure 3] This is a schematic diagram showing how a piercing tool punches through a steel plate. [Figure 4] This is a schematic diagram illustrating the misalignment of the earring's axis. [Figure 5] This diagram shows the angle of the cam driver. [Figure 6] This is a schematic diagram showing the measurement points for measuring the wear amount of the cam holder and cam driver. [Figure 7] This is a diagram showing the wear curve. [Figure 8] This is a schematic diagram of a cam rotation test device. [Modes for carrying out the invention]
[0014] Hereinafter, the cam device of the embodiment will be described.
[0015] FIG. 1 is an exploded view of the cam device of the embodiment. As shown in FIG. 1, the cam device 1 includes a cam holder 2 having a cam holder sliding surface 2a, and a cam slider 3 having a cam slider first sliding surface 3a that slidably contacts the cam holder sliding surface 2a of the cam holder 2 and a cam slider second sliding surface 3b, and a cam driver 4 having a cam driver sliding surface 4a that contacts the cam slider second sliding surface 3b of the cam slider 3 and drives the cam slider | 3 in a predetermined processing direction at the time of press working.
[0016] FIG. 5 is a schematic view showing a cross section of the cam slider 3 and the cam driver 4 of the cam device | 1. When a virtual surface formed at an angle θ1 inclined from the bottom surface of the cam driver 4 is defined as 4d, the angle formed by the two surfaces of the virtual surface 4d and the cam driver sliding surface 4a is defined as the cam driver inclination angle θ. The cam driver surface has a roof shape with an inclination of the cam driver inclination angle θ with respect to the horizontal plane in order to prevent core breakage. Generally, the cam driver inclination angle θ is 30°.
[0017] FIG. 2 is a schematic view of the cam device of the embodiment. The processing angle θ1 in the figure is the angle formed by the cam driver sliding surface 4a with the horizontal plane, and the cam angle θ2 is the angle formed by the cam holder sliding surface 2a with the horizontal plane. The processing required force F is a force generated when the cam slider 3 protrudes due to the lowering of the press and punches a steel plate with a pierce (not shown) provided at the tip. The press force P is a force generated by the lowering of the press. The component force V is the vertical component force applied to the cam driver sliding surface 4a of the processing required force F, and the component force Q is the vertical component force applied to the cam holder sliding surface 2a of the processing required force F. The stroke S is the extrusion width of the cam slider 3, the spring stroke S' is the movement width of the cam slider 3, and is the width returned by a gas spring or a spring (not shown). The press stroke L is the stroke width from the top dead center to the bottom dead center of the press (not shown).
[0018] Figure 2 shows the state where the press head (not shown) has descended vertically (upright) by L from the top dead center (press direction), and the cam slider 3 has moved S in the machining direction. At this time, as the press head (not shown) descends, a force P is applied to the cam holder 2, and the cam holder 2 pushes the cam slider 3 in a direction perpendicular to the cam holder sliding surface 2a (cam slider first sliding surface 3a) with a force Q. This force acts on the cam driver 3 in a direction perpendicular to the cam driver sliding surface 4a (cam slider second sliding surface 3b) with a force V, and pushes out a tool such as a piercing (not shown) in a direction parallel to the cam driver sliding surface 4a (cam slider second sliding surface 3b) with a force F.
[0019] Furthermore, the relationship between these forces is defined as follows. The relationship between pressing force P and processing force F is P = F·(cosθ2 / sin(θ1+θ2)) -(4) The component force Q acting on the cam slider surface is Q = F·(1 / sin(θ1+θ2)) -(5) The component force V acting on the cam driver surface is V = F·(1 / tan(θ1+θ2)) -(6) This is shown.
[0020] Figure 3 is a schematic diagram showing how a piercing attached to the cam device 1 punches out a steel plate, and Figure 4 is a cross-sectional view AA of the cam device 1 shown in Figure 3, and is a schematic diagram showing the misalignment of the piercing attached to the cam device 1. In Figure 4, DI represents the die and PO represents the piercing. At this time, the misalignment of the piercing PO attached to the cam device 1 can take various forms, but Figure 4 shows the state when the piercing PO's axis is misaligned downwards by a width C. In Figure 4, the solid line shows the state before the piercing axis is misaligned, and the dashed line shows the state after the piercing axis is misaligned.
[0021] The embodiment aims to reduce the misalignment of the piercing axis under high machining force.
[0022] This misalignment of the piercing axis is mainly caused by a decrease in the height of the reference cam driver 4 due to wear of the cam driver sliding surface 4a. Generally, the cam driver sliding surface 4a is the sliding surface of a brass alloy sliding member embedded with graphite.
[0023] To punch through hard, high-strength steel plates such as high-tensile steel with a piercing tool, a larger processing force F is required. Consequently, high surface pressure is generated on the cam driver sliding surface 4a, resulting in wear on the cam driver sliding surface 4a and a misalignment of the piercing shaft.
[0024] In this embodiment, the required machining force F is reduced by setting a predetermined relationship between the cam holder side component force Q and the cam driver side component force V, thereby reducing wear on the cam driver sliding surface 4a and minimizing misalignment of the pierce axis.
[0025] Holm's wear formula is generally known for material wear. The amount of wear (W) of a sliding material is given by equation (7). W=Z(P·L / P H ) -(7) This formula shows that the amount of wear (W) is proportional to the coefficient of wear Z, the load P, and the friction distance L, and the hardness P H This shows that it is inversely proportional. It also shows that load P and wear are proportional.
[0026] From equation (7), it can be seen that in order to keep the amount of wear down to a minimum, the load P must be reduced. For this reason, the inventor considered the ratio of the surface pressure generated by the cam holder side component force Q and the cam driver side component force V, which are components of the piercing force F, and evaluated various surface pressure ratios. As a result, he found that the following case is preferable for the cam holder-cam driver surface pressure ratio, which is the ratio of the surface pressure generated on the cam driver sliding surface 4a (V / Sd · cosθ(1-Gd / 100)) to the surface pressure generated on the cam holder sliding surface 2a (Q / Sh(1-Gh / 100)). The cam driver surface has a roof-like shape with an inclination of θ relative to the horizontal plane to prevent runout (see Figure 5), and θ is generally 30°. 1.0≦ (Q / Sh(1-Gh / 100)) / (V / Sd·cosθ (1-Gd / 100)) ≦ 3.0 -(1) Here, the sliding surface areas Sh and Sd are the actual sliding surface areas obtained by subtracting the chamfered groove portion, mounting hole portion, and chamfered mounting hole portion from the cam holder sliding surface 2a and the cam driver sliding surface 4a, respectively.
[0027] The numerical value of this cam holder / cam driver surface pressure ratio has a suitable range depending on the machining angle (θ1). When the machining angle (θ1) is between 0° and 45°, the following surface pressure ratios for the cam holder and cam driver, taking into account the graphite embedding rate, are preferable. 1.3 ≦ (Q / Sh(1-Gh / 100)) / (V / Sd·cosθ (1-Gd / 100) ) ≦ 1.6 -(2)
[0028] When the machining angle (θ1) is 45° to 70° and considering the graphite embedding rate, the following surface pressure ratios for the cam holder and cam driver are preferable. 1.6 ≦ (Q / Sh(1-Gh / 100)) / (V / Sd·cosθ (1-Gd / 100) ) ≦ 3.0 -(3)
[0029] When equation (1) above is satisfied, a greater load is generated on the cam holder 2 side, the burden on the cam driver 4 side is reduced, wear on the cam driver sliding surface 4a which serves as the reference surface is kept to a minimum, and the misalignment of the pierce axis is reduced.
[0030] (Example of experiment) Experimental examples are shown below, but the present invention is not limited to these experimental examples.
[0031] In the experimental example, a typical cam mechanism was used. The cam holder sliding surface was made of high-strength brass material (CAC304) with a graphite embedding rate of 30%, while the cam holder, cam slider, and cam driver were made of cast iron (FC250). As shown in Table 1, the cam holder-cam driver surface pressure ratio (Q / Sh(1-Gh / 100)) / (V / Sd ·cosθ(1-Gd / 100)) was determined when the sliding surface area Sh of the cam holder sliding surface was given by Gh(%), the sliding surface area Sd of the cam driver sliding surface was given by Gd(%), and the graphite embedding rate was given by Gd(%). In addition, the wear test (cam impact test) shown below was conducted, and the amount of wear after 100,000 impacts was determined. In Table 1, CH side refers to the cam holder side, and CD side refers to the cam driver side.
[0032] [Table 1]
[0033] In Holm's equation (6), the wear amount W represents the wear volume, but in this experimental example, the wear amount is expressed as the wear depth. That is, the wear volume is the product of the wear depth and the slider area (area of the sliding surface), and since the slider area is constant, it can be said that the wear depth and surface pressure are proportional, and in this experimental example, the wear depth was measured and used as the wear amount.
[0034] Figure 6 is a schematic diagram showing the measurement points for measuring the wear on the cam holder sliding surface 2a and the cam driver sliding surface 4a. Figure 6(a) shows nine wear measurement points on the cam holder sliding surface 2a, and Figure 6(b) shows the wear measurement points on the cam driver sliding surface 4a. The wear was measured at nine points, and the average value was taken as the wear amount.
[0035] Figure 7 shows the wear curve. As the wear curve in Figure 7 shows, there is an initial wear region (I) where wear progresses rapidly at first, and a steady-state wear region (II) where it then stabilizes. Holm's equation holds true in the steady-state wear region (II), where wear and wear distance are linearly proportional. Therefore, in the experimental example, the evaluation was based on 100,000 impact cycles in the steady-state wear region.
[0036] Figure 8 is a schematic diagram of the cam strike test apparatus. The number of strikes refers to the number of press shots, which is the number of times the press machine slide descends from top dead center, pushes the upper die down to bottom dead center, activates the cam mechanism, and returns to the original top dead center in one cycle.
[0037] Table 1 shows the test results for the cam holder-cam driver surface pressure ratio and wear amount. From these results, it can be seen that under the conditions of 1.0 ≤ (Q / Sh) / (V / Sd) ≤ 3.0, or 1.0 ≤ (Q / Sh(1-Gh / 100)) / (V / Sd·cosθ (1-Gd / 100)) ≤ 3.0, the wear amount on the cam driver side is 12 μm or less. Furthermore, in comparative examples 1 and 2, where the cam holder-cam driver surface pressure ratio was 1 or less, it was found that the wear amount on the cam driver side was greater than 12 μm, resulting in a decrease in piercing accuracy. In comparative example 3, where the cam holder-cam driver surface pressure ratio was 3 or more, it was found that the wear on the cam holder side increased abnormally and became unstable, and the wear amount on the cam driver side also increased.
[0038] (Examples of application) The embodiment can be used in devices that basically have a cam structure. For example, there are different types of cam devices, such as upper-hanging cams (for example, cam device 1 shown in Figure 1) and lower-mounted cams, each with a different structure. In a lower-mounted cam, the cam driver is fixed to the upper die of the press, and as the upper die of the press descends, it pushes out the cam slider fixed to the lower die. In this lower-mounted cam, Q and V are reversed, so when the cam holder-cam driver surface pressure ratio satisfies 1.0 ≤ (V / Sh) / (Q / Sd) ≤ 3.0 or 1.0 ≤ (V / Sh(1-Gh / 100)) / (Q / Sd·cosθ (1-Gd / 100)) ≤ 3.0, wear on the cam driver side, which is the reference surface, is suppressed. In this way, even with a lower-mounted cam, wear resistance and durability are improved, and a cam device can be made that can process high-tensile steel, which is a difficult material to process, with high processing accuracy.
[0039] The structure of the sliding material, the materials of the composition, and their composition in the embodiments are merely illustrative examples, and the present invention is not limited thereto. [Explanation of Symbols]
[0040] 1: Cam mechanism 2: Cam holder 2a: Cam holder sliding surface Sh: Cam holder sliding surface area 2b: Wear Plate 3: Cam slider 3a: Cam slider first sliding surface 3b: Cam slider second sliding surface 3c: Sliding part 4: Camdriver 4a: Cam driver sliding surface Sd: Cam driver sliding surface area 4b: Cam bottom guide 4c: Cam driver body 4D: Virtual Surface 5: Elastic member for return 6: Stopper plate 7: Slide Keeper 8: Force return 9: Press mold 10: Press die (upper die) 11: Press die (lower die) PO: Piercings DI: Dice θ: Cam driver tilt angle θ1: Machining angle θ2: Cam angle
Claims
1. A cam holder having a sliding surface, A cam slider having a first sliding surface of the cam slider that slides against the sliding surface of the cam holder, and a second sliding surface of the cam slider that slides against the sliding surface of the cam driver, A cam driver having a cam driver sliding surface that contacts the second sliding surface of the cam slider and drives the cam slider in a predetermined machining direction, A cam device having, Let Q be the component force applied to the sliding surface of the cam holder, perpendicular to the sliding surface of the cam holder. Let V be the component force applied to the cam driver sliding surface that is perpendicular to the cam driver sliding surface. Let Sh be the sliding surface area of the cam holder sliding surface. Let Sd be the sliding surface area of the cam driver sliding surface. Let Gh (%) be the graphite embedding rate of the sliding surface area Sh of the cam holder sliding surface. Let Gd (%) be the graphite embedding rate of the sliding surface area Sd of the cam driver sliding surface. When the roof-shaped cam driver tilt angle of the cam driver sliding surface is θ, A cam apparatus characterized in that the cam holder-cam driver surface pressure ratio, which is the ratio of the surface pressure (V / Sd・cosθ(1-Gd / 100)) generated on the cam driver sliding surface to the surface pressure (Q / Sh(1-Gh / 100)) generated on the cam holder sliding surface, is given by the following formula. 1.0≦(Q / Sh(1-Gh / 100)) / (V / Sd・cosθ(1-Gd / 100)) ≦3.0
2. When the machining angle (θ1), which is the angle that the cam driver sliding surface makes with the horizontal plane, is 0° or more and 45° or less, The cam device according to claim 1, characterized in that the surface pressure ratio of the cam holder to the cam driver is given by the following formula. 1.3≦Q / Sh(1-Gh / 100) / (V / Sd・cosθ(1-Gd / 100))≦1.6
3. When the machining angle (θ1), which is the angle that the cam driver sliding surface makes with the horizontal plane, is greater than 45° and less than or equal to 70°, The cam device according to claim 1, characterized in that the surface pressure ratio of the cam holder to the cam driver is given by the following formula. 1.6≦(Q / Sh(1-Gh / 100) / (V / Sd・cosθ(1-Gd / 100))≦3.0
4. A cam holder having a sliding surface, A cam slider having a first sliding surface of the cam slider that slides against the sliding surface of the cam holder, and a second sliding surface of the cam slider that slides against the sliding surface of the cam driver, A method for designing a cam device having a cam driver having a cam driver sliding surface that contacts the second sliding surface of the cam slider and drives the cam slider in a predetermined machining direction, Let Q be the component force applied to the sliding surface of the cam holder, perpendicular to the sliding surface of the cam holder. Let V be the component force applied to the cam driver sliding surface that is perpendicular to the cam driver sliding surface. Let Sh be the sliding surface area of the cam holder sliding surface. Let Sd be the sliding surface area of the cam driver sliding surface. Let Gh (%) be the graphite embedding rate of the sliding surface area Sh of the cam holder sliding surface. Let Gd (%) be the graphite embedding rate of the sliding surface area Sd of the cam driver sliding surface. When the inclination angle of the roof-shaped cam driver on the cam driver sliding surface is θ, A method for designing a cam device, characterized in that the cam holder-cam driver surface pressure ratio, which is the ratio of the surface pressure (V / Sd ・cosθ(1-Gd / 100)) generated on the cam driver sliding surface to the surface pressure (Q / Sh(1-Gh / 100)) generated on the cam holder sliding surface, is given by the following formula. 1.0≦(Q / Sh(1-Gh / 100)) / (V / Sd・cosθ(1-Gd / 100)) ≦3.0