Slide friction force generation device and pressing machine

Abstract

To generate an appropriate friction force in use, and easily allow a pin member to be easily pushed back after use.SOLUTION: A slide friction force generation device (1) comprises: a ring member (21) having a hole (H1); a pin member (22) slidably inserted into the hole (H1) of the ring member (21); and a friction force adjustment mechanism (3) that increases the friction force when the pin member (22) slides against the ring member (21) in a forward direction, which is one side of an axial direction, compared to the friction force when the pin member slides against the ring member in a reverse direction, which is the other side of the axial direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sliding friction force generating device and a press machine using the same.

Background Art

[0002] A sliding friction force generating device described in Patent Document 1 below is known. The sliding friction force generating device of this Patent Document 1 is a device used as a die cushion for supporting the lower die of a press machine from below, and includes a ring member (hole member) having a hole and a pin member (shaft member) slidably fitted into the hole of the ring member. The pin member supports the counter punch of the lower die from below while being fitted in the hole of the ring member in an interference fit state. When the sliding friction force generating device is used, that is, when a workpiece is processed by a press machine, the pin member slides downward with respect to the ring member in response to the force applied to the pin member from the counter punch. Then, the frictional force generated by this sliding acts as an upward reaction force on the counter punch, so that the counter punch is elastically supported by the pin member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when the processing of the workpiece by the press machine is completed, in order to prepare for the next processing, it is necessary to return the pin member that has slid downward to its original position. However, in Patent Document 1 mentioned above, since the pin member is fitted in a press fit state to the ring member, it is not easy to return the pin member to its original position. For example, in order to return the pin member to its original position, a large-scale device capable of pushing back the pin member upward with a force equivalent to the press force during processing is required. Alternatively, a method of inverting the pin member and the ring member up and down can also be considered, but again, a complicated mechanism for inverting up and down is required.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a sliding friction force generating device capable of generating an appropriate frictional force during use and easily pushing back the pin member after use, and a press machine equipped with the same.

Means for Solving the Problems

[0006] As a means for solving the above problems, a sliding friction force generating device according to an aspect of the present invention includes a ring member having a hole, a pin member slidably inserted into the hole of the ring member, and a friction force adjusting mechanism that increases the frictional force when the pin member slides in the forward direction, which is one axial side with respect to the ring member, more than the frictional force when sliding in the reverse direction, which is the other axial side.

[0007] According to the present invention, since the frictional force when the pin member slides in the forward direction is large, this frictional force can be used to apply an appropriate axial reaction force to a mating member such as a punch of a press machine, for example. On the other hand, since the frictional force when the pin member slides in the reverse direction is small, the pin member that has slid in the forward direction due to use can be easily returned to its original position.

[0008] Preferably, when the pin member slides in the forward direction with respect to the ring member, the friction force adjustment mechanism sets the pin member in a first state in which it is press-fitted into the ring member, and when the pin member slides in the reverse direction with respect to the ring member, the friction force adjustment mechanism sets the pin member in a second state in which the press fit is relaxed.

[0009] According to this configuration, the friction force can be appropriately increased or decreased by adjusting the interference fit between the ring member and the pin member.

[0010] In the above configuration, more preferably, in the sliding friction force generating device, the second state is a state in which the press fit is released and the pin member is clearance-fitted into the ring member.

[0011] According to this configuration, the friction force in the second state can be sufficiently reduced.

[0012] In the above configuration, more preferably, the ring member and the pin member have different linear expansion coefficients, and the friction force adjustment mechanism switches between the first state and the second state by heating or cooling at least one of the ring member and the pin member to adjust the interference fit therebetween.

[0013] According to this configuration, the first state and the second state can be easily switched by controlling the temperature of the ring member or the pin member, and the friction force can be increased or decreased according to the switching.

[0014] In the above configuration, more preferably, the linear expansion coefficient of the ring member is larger than the linear expansion coefficient of the pin member, and the friction force adjustment mechanism sets the pin member in the first state by cooling the ring member, and sets the pin member in the second state by heating the ring member.

[0015] According to this configuration, the tightening allowance between the ring member and the pin member can be sufficiently changed through heating or cooling of the ring member, and the above-described first state and second state can be appropriately created respectively.

[0016] In the above configuration, more preferably, the frictional force adjustment mechanism includes a supply unit that supplies a heat medium to the ring member, a cooler that cools the heat medium, and a heater that heats the heat medium.

[0017] According to this configuration, the ring member can be appropriately heated or cooled through temperature control of the heat medium using a heater or a cooler.

[0018] The linear expansion coefficient of the pin member may be larger than the linear expansion coefficient of the ring member. In this case, it is preferable that the frictional force adjustment mechanism sets the pin member to the first state by heating the pin member, and sets the pin member to the second state by cooling the pin member.

[0019] According to this configuration, the tightening allowance between the ring member and the pin member can be sufficiently changed through heating or cooling of the pin member, and the above-described first state and second state can be appropriately created respectively.

[0020] The ring member may include a plurality of split pieces that are disposed opposite to each other with the pin member interposed therebetween, and the frictional force adjustment mechanism may include a pressing member that sets the pin member to the first state by applying a pressing force that moves each split piece radially inward, and sets the pin member to the second state by reducing the pressing force.

[0021] According to such a configuration, since the above-described first state and second state are switched by a mechanical mechanism including a pressing member, the frictional force between the ring member and the pin member can be appropriately increased or decreased even in an environment where a heat source for heating or cooling cannot be prepared.

[0022] A press machine according to another aspect of the present invention includes a die having a forming space for receiving a workpiece, a punch inserted into the forming space of the die so as to sandwich the workpiece and process the workpiece, the above-described sliding friction force generating device that applies an axial reaction force to the punch during the processing of the workpiece, and a return device that slides the pin member of the sliding friction force generating device in the reverse direction with respect to the ring member after the processing of the workpiece.

[0023] According to the present invention, it is possible to easily push back the pin member after press working while applying a sufficient axial reaction force from the pin member to the punch during press working.

Effect of the Invention

[0024] As described above, according to the present invention, it is possible to provide a sliding friction force generating device that can generate an appropriate frictional force during use and can easily push back the pin member after use, and a press machine including the same.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

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Figure 4

Figure 5

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Figure 8

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Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0026] Hereinafter, with reference to the drawings, preferred embodiments of the sliding frictional force generating device of the present invention will be described. The sliding frictional force generating device of the present invention is a device that elastically supports a mating member by a frictional force based on sliding resistance, and can be suitably used, for example, for receiving a processing force in a machine tool such as a press machine. Alternatively, it can also be used for applications as a friction damper that supports a structure while damping vibration. Note that all of the following embodiments are examples in which the sliding frictional force generating device of the present invention is applied to a press machine, but it is not intended to limit the application of the sliding frictional force generating device.

[0027] (1) First Embodiment [Device Configuration] FIG. 1 is a cross-sectional view showing the configuration of a press machine 50 including a sliding frictional force generating device 1 according to the first embodiment of the present invention. The press machine 50 is a machine for pressing a workpiece W, and in addition to the above sliding frictional force generating device 1, includes a die 51, an upper punch 52, a lower punch 53, a punch plate 54, and a return device 55. The workpiece W is a workpiece to be formed into a predetermined shape by pressing, such as a forged part, a compacted powder body, or a fired part. As described below, in this embodiment, an example is shown in which the press machine 50 is installed such that the upper punch 52 is above the lower punch 53, but this is just an example and is not intended to limit the posture of the press machine 50.

[0028] The die 51 is a cylindrical mold that defines a forming space S1 inside for receiving the workpiece W. The die 51 is configured to be, for example, divisible so that the pressed workpiece W can be taken out.

[0029] The upper punch 52 is a member that is inserted into the forming space S1 of the die 51 from above. The upper punch 52 is arranged to protrude downward from the punch plate 54.

[0030] The punch plate 54 is arranged above the die 51 and supports the upper punch 52. The punch plate 54 is driven to move up and down by a drive mechanism (not shown). The upper punch 52 is inserted into and removed from the forming space S1 of the die 51 in accordance with the up and down drive of the punch plate 54.

[0031] The lower punch 53 is a member that is inserted into the forming space S1 of the die 51 from below. The upper punch 52 and the lower punch 53 press the workpiece W from above and below to press-process the workpiece W.

[0032] The sliding friction force generating device 1 is a device that elastically supports the lower punch 53 during the press-working of the workpiece W. Specifically, the sliding friction force generating device 1 includes a main body portion 2, a friction force adjusting mechanism 3, and a bolster 4. The main body portion 2 is a structure that applies an upward reaction force to the lower punch 53 during press-working and is arranged below the die 51 and the lower punch 53. The bolster 4 is a pedestal that supports the main body portion 2 from below. The friction force adjusting mechanism 3 is a mechanism that adjusts the magnitude of the friction force generated in the main body portion 2 as a reaction force to the lower punch 53.

[0033] The main body portion 2 includes a ring member 21, a pin member 22, a block 23, an upper backing plate 24, and a lower backing plate 25. The ring member 21 is a cylindrical (ring-shaped) member having a through-hole H1 penetrating in the vertical direction. The pin member 22 is a rod-shaped member whose axis X, which is its central axis, extends in the vertical direction, and is slidably inserted into the through-hole H1 of the ring member 21. The block 23 is disposed between the pin member 22 and the lower punch 53. However, depending on the press machine, the lower punch 53 may directly push the pin member 22, and the block 23 is not necessarily required. The upper backing plate 24 is a hollow plate material that encloses the upper portion of the pin member 22 and the block 23, and is disposed between the ring member 21 and the die 51. The lower backing plate 25 is a hollow plate material that encloses the lower portion of the pin member 22, and is disposed between the ring member 21 and the bolster 4. Hereinafter, the direction parallel to the axis X of the pin member 22 is referred to as the axial direction. In this embodiment, the axial direction is synonymous with the vertical direction.

[0034] As described above, the pin member 22 is slidably supported by the ring member 21 and is located below the lower punch 53 with the block 23 interposed therebetween. Therefore, when the workpiece W is press-worked, a downward force acts on the pin member 22 from the lower punch 53 via the block 23, and in response to this force, the pin member 22 slides downward with respect to the ring member 21. Then, the frictional force generated along with this sliding acts as an upward reaction force on the lower punch 53, whereby the lower punch 53 is elastically supported by the pin member 22. Here, the downward sliding of the pin member 22 is sliding in one side of the axial direction, which corresponds to the "forward sliding" in the present invention.

[0035] In this embodiment, the through hole H1 of the ring member 21 is formed in a circular shape when viewed in the axial direction (vertically). Correspondingly, the pin member 22 is formed in a columnar shape having an outer diameter substantially the same as the inner diameter of the ring member 21 (through hole H1). Although details will be described later, in this embodiment, the outer diameter of the pin member 22 and the inner diameter of the ring member 21 are set so that a desired interference fit is generated between the pin member 22 and the ring member 21 under the conditions of performing press working.

[0036] Inside the ring member 21, a jacket portion J1 is formed. The jacket portion J1 is a flow path for flowing a heat medium, which will be described later, supplied from the friction force adjustment mechanism 3.

[0037] FIG. 2 is a cross-sectional view showing an enlarged view of the ring member 21 and the pin member 22. As shown in this figure, an oil groove G is formed on the outer peripheral surface of the pin member 22. The oil groove G is a groove for holding lubricating oil supplied between the pin member 22 and the ring member 21. For example, the oil groove G has a plurality of transverse grooves G1 extending in the circumferential direction and a plurality of longitudinal grooves G2 extending in the axial direction. The longitudinal grooves G2 are formed so as to extend in the axial direction (vertically) over a range generally corresponding to the thickness of the ring member 21. The transverse grooves G1 are provided at a plurality of positions from the upper end to the lower end of the longitudinal grooves G2 and intersect the longitudinal grooves G2 respectively.

[0038] In this embodiment, both the ring member 21 and the pin member 22 are made of metal. However, the materials (metals) constituting the two members 21 and 22 are different from each other. Specifically, in this embodiment, the materials of the two members 21 and 22 are selected such that the linear expansion coefficient of the ring member 21 is larger than that of the pin member 22. Although various combinations of such materials can be considered, as an example, the material of the ring member 21 can be tool steel and the material of the pin member 22 can be cemented carbide. Since the linear expansion coefficient (thermal expansion rate) of the ring member 21 is relatively large, the dimensional change of the ring member 21 in response to a temperature change is larger than that of the pin member 22. This means that the interference fit between the ring member 21 and the pin member 22, that is, the amount obtained by subtracting the inner diameter of the ring member 21 (through hole H1) from the outer diameter of the pin member 22, changes depending on the temperature conditions.

[0039] As shown in FIG. 1, the frictional force adjusting mechanism 3 includes a circulation device 31 that supplies a heat medium to the ring member 21 while circulating the heat medium, a heater 32 that heats the heat medium, and a cooler 33 that cools the heat medium. Such a frictional force adjusting mechanism 3 can adjust the interference fit between the ring member 21 and the pin member 22 by heating or cooling the ring member 21 via the heat medium. By adjusting this interference fit, the frictional force when the pin member 22 slides relative to the ring member 21 is adjusted. The heat medium can be of any type as long as it can adjust the temperature of the ring member 21 within a desired range, but for example, a liquid such as water or oil is suitable. Note that the circulation device 31 corresponds to the "supply unit" in the present invention.

[0040] In this embodiment, the heater 32 and the cooler 33 can adjust the temperature within a range such that the interference fit between the ring member 21 and the pin member 22 changes from plus to minus. That is, the cooler 33 can cool the ring member 21 until the interference fit becomes a positive interference fit state. The heater 32 can heat the ring member 21 until the interference fit becomes negative, that is, until a clearance fit state in which a gap is generated between the outer periphery of the pin member 22 and the inner periphery of the ring member 21.

[0041] The heater 32 and the cooler 33 may be of any type as long as they can adjust the temperature within the above - mentioned range. For example, they may include a heat exchanger that performs heating or cooling by heat exchange with other heat media. Alternatively, they may perform heating or cooling by electric energy.

[0042] The circulation device 31 is a device that circulates the heat medium between the heater 32 and the ring member 21 or between the cooler 33 and the ring member 21. Specifically, the circulation device 31 includes a circulation line L, a first pump P1, a second pump P2, a first switching valve V1, and a second switching valve V2. The circulation line L is a group of pipes that connect the heater 32, the cooler 33, and the ring member 21 to each other. The first pump P1 is a pump that discharges the heat medium heated by the heater 32 and is built into the heater 32. The second pump P2 is a pump that discharges the heat medium cooled by the cooler 33 and is built into the cooler 33. The first switching valve V1 and the second switching valve V2 are valves that switch the flow of the heat medium on the circulation line L.

[0043] The circulation line L has a first supply line L1a, a second supply line L1b, a common supply line L2, a common return line L3, a first return line L4a, and a second return line L4b. The first supply line L1a is a pipe that connects the first pump P1 and the first switching valve V1. The second supply line L1b is a pipe that connects the second pump P2 and the first switching valve V1. The common supply line L2 is a pipe that connects the first switching valve V1 and the jacket part J1 of the ring member 21. The common return line L3 is a pipe that connects the jacket part J1 of the ring member 21 and the second switching valve V2. The first return line L4a is a pipe that connects the second switching valve V2 and the heater 32. The second return line L4b is a pipe that connects the second switching valve V2 and the cooler 33.

[0044] The first switching valve V1 is arranged at the position where the first supply line L1a, the second supply line L1b, and the common supply line L2 intersect. The second switching valve V2 is arranged at the position where the first return line L4a, the second return line L4b, and the common return line L3 intersect.

[0045] The returning device 55 is a device that pushes the slid pin member 22 back to its original position after press working when the pin member 22 slides downward in response to the downward force applied from the lower punch 53 during press working. That is, the returning device 55 slides the pin member 22 upward with respect to the ring member 21. The returning device 55 can adopt various structures as long as it can slide the pin member 22 upward. As an example, the returning device 55 in the present embodiment includes a rod 551 that supports the pin member 22 from below and an actuator (not shown) that drives the rod 551 upward. Here, the upward sliding of the pin member 22 refers to the sliding to the other side in the axial direction, which corresponds to the "reverse sliding" in the present invention.

[0046] [Operation during press working] The operation when the workpiece W is press worked using the press 50 configured as described above will be described. As shown in FIG. 3, the press working is performed with the ring member 21 cooled by the cooler 33. That is, the low-temperature heat medium cooled by the cooler 33 is supplied to the jacket portion J1 of the ring member 21 through the second supply line L1b and the common supply line L2, and the heat medium led out from the jacket portion J1 is returned to the cooler 33 through the common return line L3 and the second return line L4b. The heat medium returned to the cooler 33 is cooled again by the cooler 33 and then supplied to the jacket portion J1 of the ring member 21. In this way, the ring member 21 is cooled by the circulation of the low-temperature heat medium between the cooler 33 and the ring member 21. In FIG. 3, only the lines through which the heat medium flows are shown in thick lines to represent the flow of the heat medium.

[0047] In order to cause the circulation of the heat medium as described above, during press working, the second pump P2 is driven and the first pump P1 is stopped. Also, the first switching valve V1 is switched to a state in which only the flow from the second supply line L1b to the common supply line L2 is allowed, and the second switching valve V2 is switched to a state in which only the flow from the common return line L3 to the second return line L4b is allowed. Thereby, a flow of the heat medium as shown by the thick line in FIG. 3 is generated, and the ring member 21 is cooled. Note that the cooling of the ring member 21 here means that the temperature is lowered to a temperature lower than the temperature of the ring member 21 after press working described later. Therefore, the temperature after cooling may be normal temperature or a temperature higher than this.

[0048] When the ring member 21 is cooled, the ring member 21 thermally contracts. As a result, the inner diameter of the ring member 21 (through hole H1) becomes smaller than the outer diameter of the pin member 22, and the pin member 22 is in an interference fit state. That is, the interference, which is the amount obtained by subtracting the inner diameter of the ring member 21 from the outer diameter of the pin member 22, becomes positive, and the pin member 22 is firmly held by the ring member 21. Note that such an interference fit state corresponds to the "first state" in the present invention.

[0049] When the pin member 22 is in the interference fit state as described above, the frictional force between the pin member 22 and the ring member 21 increases. As a result, it becomes possible to apply a sufficient reaction force from the pin member 22 to the lower punch 53, and sufficient pressing force required for forming the workpiece W is ensured during press working. Also, when the pressing force increases more than necessary, the pin member 22 slides downward with respect to the ring member 21, and the load is absorbed by the sliding. Thereby, it is possible to prevent an excessive pressing force from being applied to the workpiece W or the die 51.

[0050] [Operation after press working] Next, the operation after press working will be described. After press working, as shown in FIG. 4, the ring member 21 is heated using the heater 32. That is, the high-temperature heat medium heated by the heater 32 is supplied to the jacket portion J1 of the ring member 21 via the first supply line L1a and the common supply line L2, and the heat medium derived from the jacket portion J1 is returned to the heater 32 via the common return line L3 and the first return line L4a. The heat medium returned to the heater 32 is reheated by the heater 32 and then supplied to the jacket portion J1 of the ring member 21. In this way, the ring member 21 is heated by the circulation of the high-temperature heat medium between the heater 32 and the ring member 21. In FIG. 4, only the lines through which the heat medium flows are shown in thick lines to represent the flow of the heat medium.

[0051] In order to cause the circulation of the heat medium as described above, during press working, the first pump P1 is driven and the second pump P2 is stopped. Also, the first switching valve V1 is switched to a state in which only the flow from the first supply line L1a to the common supply line L2 is allowed, and the second switching valve V2 is switched to a state in which only the flow from the common return line L3 to the first return line L4a is allowed. Thereby, the flow of the heat medium as shown by the thick line in FIG. 4 is generated, and the ring member 21 is heated.

[0052] When the ring member 21 is heated, the ring member 21 thermally expands. As a result, the inner diameter of the ring member 21 (through hole H1) exceeds the outer diameter of the pin member 22, and the pin member 22 is in a clearance fit state. That is, the interference between the pin member 22 and the ring member 21 becomes negative, and a gap is formed between the pin member 22 and the ring member 21. Note that such a clearance fit state, in other words, a state in which the interference fit is released, corresponds to the "second state" in the present invention.

[0053] When the pin member 22 is in the clearance fit state as described above, the frictional force between the pin member 22 and the ring member 21 decreases. This means that the pin member 22, which slid downward during the pressing process, can be easily returned to its original position by the return device 55. That is, when the pin member 22 slides downward with respect to the ring member 21 due to the pressing force during the pressing process, for example, after taking out the workpiece W through the splitting of the die 51 or the like, it is necessary to slide the pin member 22 upward by the return device 55 and return it to its original position before performing the next pressing process. At this time, if the pin member 22 is in the clearance fit state as described above, the pin member 22 can be pushed back upward by applying a relatively small force to the pin member 22 from the return device 55.

[0054] [Examples of Material and Dimensions] As described above, in this embodiment, the pin member 22 is in an interference fit state by cooling the ring member 21 during the pressing process, and the pin member 22 is in a clearance fit state by heating the ring member 21 after the pressing process. Such a state change between the interference fit state and the clearance fit state can be realized by setting the materials and dimensions of the ring member 21 and the pin member 22 as follows.

[0055] For example, the material of the ring member 21 is tool steel with a linear expansion coefficient of 11.5×10 -6 and the material of the pin member 22 is cemented carbide with a linear expansion coefficient of 5.0×10 -6 . Also, the temperature difference during cooling and heating of the ring member 21 is set to 100°C. In this case, if the inner and outer diameters of the ring member 21 and the pin member 22 are set so that an interference equivalent to 0.05% of the diameter of the pin member 22 is obtained during cooling (resulting in an interference fit of 0.05%), when heated with a 100°C temperature rise, the interference decreases to an amount equivalent to -0.015% of the diameter of the pin member 22, and the interference turns negative. As a result, a gap is generated between the outer circumference of the pin member 22 and the inner circumference of the ring member 21, and a clearance fit state is obtained.

[0056] [Operating Effects] As described above, in the first embodiment, the tightening allowance between the ring member 21 and the pin member 22 is adjusted through temperature control by the frictional force adjustment mechanism 3 so that the frictional force between the ring member 21 and the pin member 22 changes during and after the pressing process. That is, during the pressing process in which the pin member 22 slides downward (forward direction) with respect to the ring member 21, the ring member 21 is cooled by the frictional force adjustment mechanism 3 (cooler 33) so that a shrink fit state in which the tightening allowance becomes positive can be obtained. On the other hand, after the pressing process, when the pin member 22 slides upward (reverse direction) with respect to the ring member 21, the ring member 21 is heated by the frictional force adjustment mechanism 3 (heater 32) so that a clearance fit state in which the tightening allowance becomes negative can be obtained. According to such a configuration, there is an advantage that while generating an appropriate frictional force during the pressing process, the pin member 22 can be easily pushed back after the pressing process.

[0057] That is, in the first embodiment, during the pressing process, the pin member 22 tends to slide downward with respect to the ring member 21 under the force from the lower punch 53. At this time, since the pin member 22 is in a shrink fit state, as a result, the frictional force between the pin member 22 and the ring member 21 increases, and an appropriate axial reaction force (upward reaction force) based on this frictional force can be applied to the lower punch 53.

[0058] On the other hand, after the pressing process, an operation to return the pin member 22 that has slid downward to its original position, that is, an operation to slide the pin member 22 upward, is performed by the return device 55. At this time, since the pin member 22 is in a clearance fit state, as a result, the frictional force between the pin member 22 and the ring member 21 decreases, and the upward pressing force that needs to be applied to the pin member 22 from the return device 55 can be kept low. Thereby, it becomes unnecessary to prepare a return device 55 with particularly high capabilities, so the return device 55 can be made more compact or its structure can be simplified.

[0059] Moreover, since the switching between the shrink fit state and the clearance fit state described above is realized by heating or cooling the ring member 21, the frictional force can be easily increased or decreased through temperature control of the ring member 21.

[0060] In particular, in the first embodiment, the linear expansion coefficient of the ring member 21 is larger than that of the pin member 22. Such a ring member 21 is likely to contract when cooled and is likely to expand when heated. Therefore, through heating or cooling of the ring member 21, the interference fit between the ring member 21 and the pin member 22 can be sufficiently changed, and the above-described interference fit state and clearance fit state can be appropriately created respectively.

[0061] Also, in the first embodiment, the heat medium is circulated between the heater 32 or the cooler 33 and the ring member 21, whereby the ring member 21 is heated or cooled. According to such a configuration, the ring member 21 can be appropriately heated or cooled through temperature control of the heat medium using the heater 32 or the cooler 33.

[0062] (2) Second Embodiment In the above first embodiment, the ring member 21 is heated or cooled (that is, temperature is adjusted) in order to adjust the interference fit between the ring member 21 and the pin member 22, but the object of temperature adjustment is not limited to the ring member 21. For example, the pin member 22 instead of the ring member 21 may be temperature-adjusted, or both the ring member 21 and the pin member 22 may be temperature-adjusted. Hereinafter, an example in which both the ring member 21 and the pin member 22 are temperature-adjusted as described above will be described as the second embodiment.

[0063] FIG. 5 is a cross-sectional view showing the configuration of a press machine 50A including a sliding frictional force generating device 1A according to the second embodiment of the present invention. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. As shown in FIG. 5, the sliding frictional force generating device 1A of the second embodiment is different from the sliding frictional force generating device 1 of the first embodiment in that it includes a frictional force adjusting mechanism 3A capable of heating or cooling both the ring member 21 and the pin member 22.

[0064] Specifically, the frictional force adjustment mechanism 3A includes a first adjustment mechanism 3A1 that heats or cools the ring member 21, and a second adjustment mechanism 3A2 that heats or cools the pin member 22. The first adjustment mechanism 3A1 has the same structure as the frictional force adjustment mechanism 3 of the first embodiment, and includes a circulation device 31, a heater 32, and a cooler 33. The second adjustment mechanism 3A2 is basically the same as the first adjustment mechanism 3A1 except that the object to which the heat medium is supplied is the pin member 22. That is, the second adjustment mechanism 3A2 includes a circulation device 35 that supplies the pin member 22 while circulating the heat medium, a heater 36 that heats the heat medium, and a cooler 37 that cools the heat medium.

[0065] The structure of the circulation device 35 is the same as that of the circulation device 31 of the first adjustment mechanism 3A1, that is, the circulation device 31 of the frictional force adjustment mechanism 3 in the first embodiment (FIG. 1). That is, the circulation device 35 includes a circulation line L' that connects the pin member 22, the heater 36, and the cooler 37, pumps P3 and P4 that discharge the heat medium, and switching valves V3 and V4 that switch the flow of the heat medium.

[0066] A jacket portion J2 is formed inside the pin member 22. The heat medium supplied from the second adjustment mechanism 3A2 described above is introduced into the jacket portion J2. Thereby, the pin member 22 is heated or cooled.

[0067] As described above, in the second embodiment, since two types of mechanisms, i.e., the first adjustment mechanism 3A1 for heating or cooling the ring member 21 and the second adjustment mechanism 3A2 for heating or cooling the pin member 22, are provided, there is an advantage that the clamping allowance between the ring member 21 and the pin member 22 can be adjusted within a sufficient range. For example, if the ring member 21 is cooled by the first adjustment mechanism 3A1 and the pin member 22 is heated by the second adjustment mechanism 3A2, the ring member 21 can be contracted and the pin member 22 can be expanded. Conversely, if the ring member 21 is heated by the first adjustment mechanism 3A1 and the pin member 22 is cooled by the second adjustment mechanism 3A2, the ring member 21 can be expanded and the pin member 22 can be contracted. In this way, since the ring member 21 and the pin member 22 can be thermally deformed in different directions, the clamping allowance between the ring member 21 and the pin member 22 can be adjusted within a sufficient range, and the above-described interference fit state and clearance fit state can be appropriately created respectively.

[0068] (3) Third Embodiment In the above first and second embodiments, an example in which a device such as a heating furnace for increasing the ambient temperature of the press machine is not used, that is, an example in which press working (cold pressing) is performed at room temperature has been described. However, for example, press working (hot pressing) may be performed in a high-temperature atmosphere in a heating furnace. An example thereof will be described as the third embodiment.

[0069] FIG. 6 is a cross-sectional view showing the configuration of a press machine 50B including a sliding frictional force generating device 1B according to the third embodiment of the present invention. In the third embodiment, the same reference numerals are given to the same components as in the first embodiment, and the detailed description thereof is omitted. As shown in FIG. 6, the press machine 50B of the third embodiment is different from the press machine 50 of the first embodiment in that it is housed inside a heating furnace 60. Further, the press machine 50B is not provided with a temperature adjusting means using a heat medium such as the frictional force adjusting mechanism 3 of the first embodiment.

[0070] The heating furnace 60 includes a furnace body 61 and a heat source (not shown in the figure) that raises the internal temperature of the furnace body 61. That is, the press machine 50B is a so-called hot press machine that presses the workpiece W inside the furnace body 61 that has been heated to a high temperature.

[0071] The sliding friction force generating device 1B includes a ring member 21 and a pin member 22 having the same shape as the sliding friction force generating device 1 of the first embodiment. However, in the third embodiment, the magnitude relationship of the linear expansion coefficients of the two members 21 and 22 is opposite to that of the first embodiment. That is, in the third embodiment, the materials of the two members 21 and 22 are selected such that the linear expansion coefficient of the pin member 22 is larger than the linear expansion coefficient of the ring member 21. Although various combinations of such materials are conceivable, as an example, the material of the ring member 21 can be cemented carbide and the material of the pin member 22 can be titanium carbonitride.

[0072] The outer diameter of the pin member 22 and the inner diameter of the ring member 21 are set such that the former is slightly smaller than the latter at normal temperature. In other words, the pin member 22 is set in an interference fit state. That is, in the third embodiment, at normal temperature, the interference of the ring member 21 and the pin member 22 becomes negative, and a slight gap is generated between the outer periphery of the pin member 22 and the inner periphery of the ring member 21.

[0073] The press machine 50B presses the workpiece W in the high-temperature atmosphere inside the heating furnace 60. That is, during the press working, the heating furnace 60 operates to raise the ambient temperature of the press machine 50B. This raises the temperature of each part including the ring member 21 and the pin member 22. Specifically, the heating furnace 60 heats the ring member 21 and the pin member 22 until the interference of the ring member 21 and the pin member 22 becomes positive, that is, until the pin member 22 is in an interference fit state. Since the pin member 22 is in an interference fit state, a sufficient reaction force suitable for press working is applied from the pin member 22 to the lower punch 53.

[0074] On the other hand, after the pressing process, the heating by the heating furnace 60 is stopped, or the press 50B is removed from the heating furnace 60. As a result, the ring member 21 and the pin member 22 are cooled. By this cooling, the interference fit of the ring member 21 and the pin member 22 changes from positive to negative, and the pin member 22 becomes in a clearance fit state. This facilitates the pushing-back operation of the pin member 22 by the returning device 55.

[0075] Thus, in the third embodiment, depending on the presence or absence of heating by the heating furnace 60, the ring member 21 and the pin member 22 are heated or cooled, thereby switching between the interference fit state and the clearance fit state. That is, the heating furnace 60 functions as a frictional force adjusting mechanism that adjusts the interference fit between the ring member 21 and the pin member 22, in other words, the frictional force between the two.

[0076] In the third embodiment, the state change between the interference fit state and the clearance fit state as described above can be realized by setting the materials and dimensions of the ring member 21 and the pin member 22 as follows.

[0077] For example, the material of the ring member 21 is a cemented carbide with a linear expansion coefficient of 5.0×10 -6 and the material of the pin member 22 is titanium carbonitride with a linear expansion coefficient of 7.5×10 -6 Also, the temperature increase range due to the heating of the heating furnace 60 is set to 700°C. In this case, if the inner and outer diameters of the ring member 21 and the pin member 22 are set so that an interference fit corresponding to 0.15% of the diameter of the pin member 22 is obtained during heating by the heating furnace 60 (resulting in an interference fit of 0.15%), then at room temperature when the temperature has dropped by 700°C, the interference fit decreases to an amount corresponding to -0.025% of the diameter of the pin member 22, and the interference fit turns negative. As a result, a gap is formed between the outer periphery of the pin member 22 and the inner periphery of the ring member 21, and a clearance fit state is obtained.

[0078] (4) Fourth Embodiment In the above first to third embodiments, the interference between the ring member 21 and the pin member 22 is adjusted by heating or cooling at least one of the ring member 21 and the pin member 22, but such an adjustment of the interference can also be achieved by a mechanical mechanism. One example of such an adjustment will be described as the fourth embodiment.

[0079] 7 and 8 are a cross-sectional view and a plan view showing the configuration of a sliding friction force generating device 1C according to a fourth embodiment of the present invention. As shown in these drawings, the sliding friction force generating device 1C of the fourth embodiment includes a ring member 121, a pin member 122, a base 123, and a friction force adjusting mechanism 103.

[0080] The pin member 122 is a cylindrical member extending in the vertical direction, similar to the pin member 22 of the first embodiment.

[0081] The ring member 121 does not have an integral structure like the ring member 21 of the first embodiment, but has a divided structure consisting of a plurality of divided pieces. That is, the ring member 121 of the fourth embodiment includes a pair of divided pieces 121a obtained by dividing a circular ring into two equal parts. Each divided piece 121a has a roughly semicircular arc shape and is disposed so as to face each other with the pin member 122 therebetween. This forms the ring member 121 having a roughly circular hollow portion H2 (hole) for receiving the pin member 122.

[0082] The base 123 is a block body having a circular receiving hole H3 penetrating in the thickness direction. The ring member 121 is concentrically received in the receiving hole H3.

[0083] The frictional force adjustment mechanism 103 includes a pair of pressing pins 104 capable of contacting the outer periphery of each divided piece 121a of the ring member 121, and a pair of advancing and retreating rods 105 for radially inwardly pressing each pressing pin 104. The pressing pins 104 correspond to the "pressing member" in this invention.

[0084] The pair of pressing pins 104 are arranged along a straight line Y (FIG. 8) that extends in the radial direction (horizontal direction) through the center of the ring member 121, and are supported by the base 123 so as to be slidable along the straight line Y.

[0085] The pair of advancing and retracting rods 105 are supported so as to be able to advance and retract in the vertical direction above the outer end portions of the respective pressing pins 104, that is, above the end portions of the respective pressing pins 104 on the side opposite to the ring member 121. The advancing and retracting rod 105 is a rod having a rectangular cross-section in this embodiment. The advancing and retracting rod 105 has a tapered portion 105a (FIG. 7) on the inner surface at its lower end portion. Due to the presence of this tapered portion 105a, the lower end portion of the advancing and retracting rod 105 is formed to be thinner toward the bottom. Note that a drive portion (not shown) composed of a cam mechanism or the like for driving the advancing and retracting rod 105 in the vertical direction is provided above the advancing and retracting rod 105.

[0086] A pair of slide holes H4 are formed at two locations on the base 123 corresponding to the respective advancing and retracting rods 105. Each slide hole H4 is a through hole having a rectangular shape in plan view that can accommodate each advancing and retracting rod 105.

[0087] Each pressing pin 104 is arranged so as to extend horizontally between the accommodation hole H3 and the slide hole H4 in the base 123. That is, the pressing pin 104 is arranged such that the inner end portion close to the ring member 121 slightly enters the accommodation hole H3, and the outer end portion far from the ring member 121 slightly enters the slide hole H4.

[0088] FIG. 9 is a cross-sectional view showing the states of the ring member 121 and the pin member 122 during press working. As shown in this figure, during press working, the advancing and retracting rod 105 descends (extends) and is inserted into the slide hole H4. At this time, the tapered portion 105a of the advancing and retracting rod 105 abuts against the outer end portion of the pressing pin 104. As a result, the pressing pin 104 is pressed radially inward and starts to move in the same direction. The amount of movement of the pressing pin 104 radially inward becomes maximum when the tapered portion 105a has descended until it passes through the pressing pin 104.

[0089] The pressing pin 104 that has moved radially inward presses each split piece 121a of the ring member 121 radially inward. As a result, each split piece 121a moves in a direction approaching each other, and the diameter of the hollow portion H2 formed between both split pieces 121a, that is, the inner diameter of the ring member 121, is reduced. By reducing the inner diameter, the split piece 121a is strongly pressed against the pin member 122. This creates an interference fit state where the interference between the ring member 121 and the pin member 122 becomes positive. That is, in the fourth embodiment, the inner diameter of the ring member 121 is reduced and the pin member 122 is brought into an interference fit state by the advancing / retreating rod 105 inserted into the slide hole H4 pressing the split piece 121a radially inward via the pressing pin 104.

[0090] On the other hand, after the pressing process, as shown in FIG. 7, when the advancing / retreating rod 105 ascends (retreats), the pressing by the above-described pressing pin 104 is released. This release of the pressing brings about an increase in the inner diameter of the ring member 121. As a result, the interference between the ring member 21 and the pin member 22 changes from positive to negative, and the pin member 22 is in a clearance fit state. In other words, in the fourth embodiment, the inner diameter of the ring member 121 is increased and the pin member 122 is brought into a clearance fit state by the advancing / retreating rod 105 withdrawn from the slide hole H4 releasing the pressing by the pressing pin 104.

[0091] As described above, in the fourth embodiment, the interference fit state and the clearance fit state can be switched by a mechanical mechanism combining the advancing / retreating rod 105 and the pressing pin 104. According to such a configuration, even in an environment where a heat source for heating or cooling cannot be prepared, the frictional force between the ring member 121 and the pin member 122 can be appropriately increased or decreased.

[0092] Here, in the fourth embodiment, an example in which the ring member 121 and the pin member 122 are provided in a one-to-one relationship has been described. However, like the multi-row sliding frictional force generating device shown in FIG. 10, one ring member 221 may be shared among a plurality of pin members 222. Specifically, in the example of FIG. 10, it includes three pin members 222 arranged in a row, and a ring member 221 composed of a pair of split pieces 221a oppositely arranged so as to sandwich each pin member 222 from both sides. The ring member 221 is housed in an elliptical housing hole H7 formed in the base 223. Semi-circular recesses are formed at three locations corresponding to the pin members 222 in each split piece 221a. As a result, three substantially circular hollow portions H6 (holes) surrounding each pin member 222 are formed between the split pieces 221a. Further, corresponding to the three pin members 222, the base 223 is provided with three pairs of pressing pins 204 and three pairs of advancing and retracting rods 205. These pressing pins 204 and advancing and retracting rods 205 constitute a frictional force adjusting mechanism 203 that increases or decreases the frictional force by separating and contacting the pair of split pieces 221a.

[0093] Note that in FIG. 10, an example in which the configuration of the fourth embodiment (FIGS. 7 to 9) is changed to a form in which one ring member is shared among a plurality of pin members has been described. However, the same change is also possible in the first to third embodiments (FIGS. 1 to 6) described above.

[0094] (5) Other Modification Examples In each of the above embodiments, the state of the pin member after pressing (the second state) is a clearance fit state in which a gap is formed between the pin member and the ring member. However, the pin member after pressing only needs to be in a state in which the interference fit is relaxed compared to the pressing process, and it is not necessarily in a clearance fit state. That is, after pressing, it is only necessary to reduce the interference between the ring member and the pin member so that the frictional force between them decreases compared to the pressing process, and there is no need to change the fitting until the interference becomes negative (that is, until a gap is formed between the ring member and the pin member).

[0095] In each of the above embodiments, the frictional force between the ring member and the pin member is increased or decreased by adjusting the interference fit between them. However, it is also possible to increase or decrease the frictional force by methods other than adjusting the interference fit. For example, the frictional force may be increased or decreased by increasing or decreasing the amount of lubricating oil supplied between the ring member and the pin member.

[0096] In each of the above embodiments, a cylindrical member, that is, a rod-shaped body having a circular cross section, is used as the pin member. However, as shown in FIG. 11, a pin member 322 made of a rod-shaped body having a polygonal cross section may be used. Specifically, the sliding frictional force generating device 1D in the example of FIG. 11 includes a pin member 322 having an octagonal cross section and a ring member 321 surrounding the pin member 322. The ring member 321 is composed of four split pieces 321a. The four split pieces 321a are combined so that a hollow portion H8 (hole) having a rectangular shape in plan view capable of accommodating the pin member 322 is defined inside. As described above, in the example of FIG. 11, since the hollow portion H8 of the ring member 321 is rectangular and the pin member 322 is octagonal, triangular gaps HG are formed at the four corners of the hollow portion H8 in plan view. This gap HG can be used as an axial oil groove (longitudinal groove) for holding the lubricating oil supplied between the inner periphery of the ring member 321 and the outer periphery of the pin member 322. Therefore, in the example of FIG. 11, the longitudinal groove G2 formed on the outer periphery of the pin member 22 in the first embodiment and the like can be omitted.

[0097] In the above-described third embodiment (FIG. 6), an example in which the heating furnace 60 is employed as the frictional force adjusting mechanism has been described. However, instead of the heating furnace 60, a frictional force adjusting mechanism may be configured using the principle of induction heating. For example, an induction heating coil may be disposed outside the ring member 21. Even in this case, since the linear expansion coefficient of the pin member 22 is set higher than that of the ring member 21, when heated (when current is applied to the coil), the ring member 21 and the pin member 22 are in an interference fit state, and when not heated (when current is not applied to the coil), both members are cooled and are in a clearance fit state. As described above, the induction heating coil and the heating furnace 60 are heating sources that act as frictional force adjusting mechanisms.

[0098] In the embodiments shown in FIGS. 7 to 10, the interference fit state and the clearance fit state were switched by the lowering and raising of the forward and reverse rods 105 and 205. Instead of this, the interference fit state and the clearance fit state may be switched by a cam mechanism having a cam surface that abuts against the outer ends of the pressing pins 104 and 204.

Explanation of Reference Numerals

[0099] 1, 1A, 1B, 1C, 1D Sliding Friction Force Generation Device 3, 3A Friction Force Adjusting Mechanism 21, 121, 221, 321 Ring Member 22, 122, 222, 322 Pin Member 31 Circulation Device (Supply Unit) 32, 36 Heater 33, 37 Cooler 50, 50A, 50B Press 51 Die 52 Upper Punch (Punch) 53 Lower Punch (Punch) 55 Return Device 104 Pressing Pin (Pressing Member) H1, H2, H6, H8 Hole W Workpiece

Claims

1. A ring member having a hole, A pin member slidably inserted into the hole of the ring member, A sliding friction force generating device comprising a friction force adjusting mechanism for increasing the friction force when the pin member slides in the forward direction, which is one axial side with respect to the ring member, more than the friction force when sliding in the reverse direction, which is the other axial side.

2. In the sliding friction force generating device according to Claim 1, The friction force adjusting mechanism sets the pin member in a first state of interference fit with the ring member when the pin member slides in the forward direction with respect to the ring member, and sets the pin member in a second state in which the interference fit is relaxed when the pin member slides in the reverse direction with respect to the ring member. A sliding friction force generating device.

3. In the sliding friction force generating device according to Claim 2, The second state is a state in which the interference fit is released and the pin member is clearance-fitted to the ring member. A sliding friction force generating device.

4. In the sliding friction force generating device according to Claim 2 or 3, The ring member and the pin member have different linear expansion coefficients from each other, The friction force adjusting mechanism switches between the first state and the second state by heating or cooling at least one of the ring member and the pin member to adjust the interference fit between the two. A sliding friction force generating device.

5. In the sliding friction force generating device according to Claim 4, The linear expansion coefficient of the ring member is larger than the linear expansion coefficient of the pin member, The friction force adjusting mechanism sets the pin member in the first state by cooling the ring member, and sets the pin member in the second state by heating the ring member. A sliding friction force generating device.

6. In the sliding friction force generating device according to Claim 5, The friction force adjusting mechanism includes a supply unit for supplying a heat medium to the ring member, a cooler for cooling the heat medium, and a heater for heating the heat medium. A sliding friction force generating device.

7. In the sliding friction force generating device according to Claim 4, The linear expansion coefficient of the pin member is larger than the linear expansion coefficient of the ring member, The friction force adjusting mechanism sets the pin member in the first state by heating the pin member, and sets the pin member in the second state by cooling the pin member. A sliding friction force generating device.

8. In the sliding friction force generating device according to Claim 2 or 3, The ring member includes a plurality of split pieces that are arranged opposite to each other with the pin member therebetween. The frictional force adjustment mechanism includes a pressing member that sets the pin member in the first state by applying a pressing force that moves each of the split pieces radially inward, and sets the pin member in the second state by reducing the pressing force, and is a sliding frictional force generating device.

9. A die having a forming space for receiving a workpiece, A punch that is inserted into the forming space of the die so as to sandwich the workpiece and processes the workpiece, The sliding frictional force generating device according to any one of claims 1 to 3, which applies an axial reaction force to the punch during processing of the workpiece, A press machine comprising: a return device that slides the pin member of the sliding frictional force generating device in the reverse direction with respect to the ring member after processing of the workpiece.

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