JP6581165B2 - Sliding friction force generation mechanism by fitting and die cushion of press machine - Google Patents

Description

  The present invention relates to a sliding frictional force generating mechanism by fitting and a die cushion of a press machine using the same.

  To fit the shaft and hole, there is a “gap fit” that provides a slidable fit, “an interference fit” that secures the shaft to the hole, and an “intermediate fit” that is an intermediate fit between the two. It has been known. These are selected by specifying the dimensional tolerance of the hole diameter and shaft diameter. These are known, for example, in Non-Patent Document 1, etc., and according to “4.10.2” of Non-Patent Document 1, “interference fit: always when a hole and a shaft are assembled. It is said that it is a "fit that can be tightened". Such an interference fit is used when it does not basically move after assembly and does not disassemble. Assembling requires press fitting, shrink fitting, and cold fitting.

  On the other hand, as a device that uses sliding friction force, there is a friction damper (Patent Document 1) that attenuates vibration during dehydration of a fully automatic washing machine, and a friction damper (Patent Document 2) that attenuates shaking of a building during an earthquake. Are known. These friction dampers are such that a piston is slidably accommodated in a cylinder, and a friction material is provided on the outer periphery of the piston so as to obtain a predetermined friction force.

  In Patent Document 1, the material of the friction material is not referred to, and is appropriately selected. Patent Document 2 discloses using a synthetic resin, a sintered metal, a metal sheet made of expanded metal or a wire mesh, or a porous sintered metal filled with polyimide resin or PTFE as a friction material. These friction dampers use sliding frictional resistance, but only absorb vibration energy in a high rotation range and radiate it as heat energy. Therefore, a high frictional force cannot be stably generated in the driving cycle of the press machine.

  Patent Document 3 discloses a magnetically controlled friction damper that can control a tightening margin by controlling magnetism. In paragraph [0013] of Patent Document 3, various uses of the friction damper are exemplified. Examples of the friction material include synthetic resins such as polyethylene and nylon.

  In Patent Document 4, when an upper mold is manufactured integrally with an injection mold, the mold is bent by the injection pressure, and a burr is formed in the gap between the lower mold and the upper mold. Teaches the technique of dividing and fitting the first entering piece and the second entering piece. For this reason, even if the upper die is bent, each entering piece comes into close contact with the lower die by the material pressure with which the upper die is pressed. At this time, the entering piece is slidably fitted to the upper die so as not to generate burrs due to material intrusion from the split surface. However, the margin is small. This technique is rather about the seal structure and does not teach the use of frictional forces.

JP 05-248468 A Japanese Patent Laying-Open No. 2015-031385 Japanese translation of PCT publication No. 2003-529028 Japanese Utility Model Publication No. 07-2020

JIS B0401-1 (1988) "Dimensional tolerance and fit method Part 1: Basics of tolerance, dimension difference and fit"

  When a workpiece made of a metal plate is punched by a press machine, a counter punch that clamps the workpiece together with the punch may be used to assist the precise shearing of the workpiece by the die and the punch by following the lowering of the punch. In order to generate such a force supported by the counter punch, a die cushion using air pressure, hydraulic pressure, or a spring is used. The die cushion is also used when back pressure is applied to the wrinkle presser that sandwiches the periphery of the workpiece together with the die when drawing the workpiece.

  Such a die cushion is installed in a frame of a press machine or a slide. For this reason, in the case of a large area cushion specification, the frame rigidity of the press machine decreases, and when molding a high-tensile material such as ultra-high tensile material, wrinkles or cracks may occur due to insufficient rigidity, or molding accuracy may be insufficient. is there. In addition, the position of the cushion pin at the time of mold design is limited to the specification of the cushion pin position determined by the press machine, which is a factor that hinders optimal mold design.

  In addition, in a die cushion that uses air pressure, a coil spring, or a spring property of an elastomer, the load increases as the pushing amount increases. Therefore, the design of the load is complicated, and when a uniform load is required, it is necessary to combine with other die cushions. On the other hand, when the hydraulic relief pressure is used as the cushion pressure, the cushion pressure depends on the speed. Therefore, when the speed is reduced like the bottom dead center of the press machine, the cushion pressure is lowered.

  On the other hand, friction dampers used in conventional washing machines, etc., use friction materials based on wear, such as rubber, synthetic resin, copper and aluminum alloys, thereby protecting the main material made of steel. Yes. For this reason, they cannot be used in a device that can withstand a large force such as a die cushion of a press machine. On the other hand, friction dampers used for vibration control of buildings can withstand strong forces, but are difficult to operate precisely and have low durability when used repeatedly over a long period of time.

  The present invention can stably exert a large load force, has high durability, and can suppress the occurrence of seizure or galling, thereby enabling the press machine die cushion, knockout overload prevention device, press overload. An object of the present invention is to provide a sliding frictional force generating mechanism that can be used in a machine that requires a high load such as a load protector device.

  The sliding frictional force generating mechanism of the present invention includes a metal hole member having a hole, a metal shaft member fitted in the hole of the hole member so as to be axially slidable, and a cooling medium between them. It comprises an oil supply mechanism that supplies lubricating oil that also serves as a feature, and the hole and the shaft member are fitted in an interference fit state.

  In such a sliding frictional force generating mechanism, it is preferable that at least one of the hole member and the shaft member is formed with a passage through which the lubricating oil or other cooling medium flows. Moreover, it is preferable that both the hole member and the shaft member are made of carbon steel, and at least one or both sliding surfaces are subjected to a hardened surface treatment. The surface roughness of the hole and the shaft member is preferably Ra 0.2 μm or less, and Ra 0.01 to 0.2 μm is preferable. Further, Ra of 0.08 to 0.2 μm is more preferable.

  A die cushion device for a press machine according to the present invention includes any one of the sliding frictional force generation mechanisms and a return mechanism that returns the pushed-in shaft member to a state before being pushed, and presses the sliding frictional force generation mechanism. It is characterized by being used for workpiece clamping as a source of machining reaction force or resistance force. The die for a press machine according to the present invention is characterized in that any one of the sliding frictional force generating mechanisms is used as a reaction force or resistance generating source of a processing pressure applied to the die.

  Another aspect of the die cushion device of the present invention includes any one of the sliding frictional force generation mechanisms and a reversing mechanism that reverses the sliding frictional force generation mechanism, and the hole of the hole member of the sliding frictional force generation mechanism is provided. A through hole in which the length of the shaft member is longer than the hole, and the reversing mechanism reverses the sliding frictional force generating mechanism for each press of the press machine, whereby the reversing mechanism is It is characterized by a return mechanism.

  A relief type die cushion device according to the present invention is a relief type die cushion device that includes a hydraulic cylinder composed of a cylinder and a piston, and that exerts a cushioning force due to the resistance of hydraulic oil coming out of the hydraulic cylinder. One of the sliding frictional force generating mechanisms is constituted by the portions that are in sliding contact with each other in the vicinity of the bottom dead center of the press machine, of the inner surface of the piston and the outer surface of the piston.

  The manufacturing method of the sliding frictional force generating mechanism according to the present invention is characterized in that the hole member and the shaft member are fitted by cold fitting.

  In the sliding frictional force generating mechanism of the present invention, an external force receiving portion that alternately receives pressing force is provided at one end and the other end of the shaft member, or an external force receiving portion that alternately receives pressing force and tensile force is provided at one end of the shaft member. It is used to generate a frictional force that is opposite to the direction of movement due to external force. At this time, since both the shaft member and the hole member are metal, and the hole and the shaft member can be slid relative to each other in the axial direction with a tight fit, a high frictional force (dynamic friction) corresponding to the tightening margin is generated. . If the length of the sliding portion (the length of the friction hole 36 in FIG. 12) is constant, this frictional force hardly changes depending on the amount of pressing of the shaft member, and exhibits a stable load capability. Also, the speed dependency is low.

  Further, since the metal slides only by interposing the lubricating oil without interposing a friction member which is easily worn such as a synthetic resin or a soft metal, it can cope with a strong pressure and has high durability. The shaft member and the hole slide through the lubricating oil supplied from the oil supply mechanism, and the frictional heat caused by the sliding is cooled by the lubricating oil, so that seizure and galling are unlikely to occur and uniform over a long period of time. Demonstrate frictional force.

  When a passage for flowing the lubricating oil or other cooling medium is formed in at least one of the hole member and the shaft member, the flow rate of the cooling medium can be increased by increasing the passage cross-sectional area. can do. When both the hole member and the shaft member are made of carbon steel and at least one or both sliding surfaces are hardened, the effect of preventing seizure and galling is high. When the surface roughness of the hole and the shaft member is Ra 0.2 μm or less, especially when Ra is 0.01 to 0.2 μm, and further Ra is 0.08 to 0.2 μm, the oil film maintaining action of the lubricating oil is high and seizure occurs. The occurrence of galling is further suppressed.

  When the shaft member is pushed into the hole of the hole member, the die cushion device of the present invention exhibits the above-described frictional force generating action. Since the shaft member is returned to the original state by the return mechanism, the frictional force can be repeatedly generated. Furthermore, since it is more compact than a conventional die cushion that uses air pressure or hydraulic pressure, the rigidity of the frame or slide is not greatly impaired even when a large cushion force is exerted. Moreover, since it is a simple structure of a shaft member and a hole member, it can arrange | position in a suitable position according to the form and molding state of a metal mold | die. As the return mechanism, an air die cushion, a hydraulic die cushion, a cam-driven knockout device, or the like can be used. Since the metal mold | die of this invention is provided with the sliding frictional force generation | occurrence | production mechanism, it can exhibit cushioning force by itself.

  The die cushion device provided with the above-described reversing mechanism can return the shaft member to the original position, that is, the state before being fitted deeply into the hole, by reversing the sliding frictional force generating mechanism with the reversing device. . Therefore, it is not necessary to use an external device like a pneumatic die cushion or a hydraulic die cushion, so that it can be made compact. Further, since there is no step of returning the shaft member to the original position, heat generation due to friction can be reduced.

  The relief type die cushion of the present invention generates a cushioning force by a normal relief back pressure until it reaches the vicinity of the bottom dead center. In the vicinity of the bottom dead center, a predetermined range between the inner surface of the cylinder and the outer peripheral surface of the piston is in sliding contact with each other, resulting in a large sliding frictional resistance. Therefore, it is possible to supplement a relief die cushion whose resistance is reduced at the bottom dead center.

  In the manufacturing method of the frictional force generating mechanism of the present invention, the hole member and the shaft member are fitted by cold fitting, so that the member is less damaged than shrink fitting or press fitting. Further, when the cooled shaft member is fitted into the hole of the hole member, the lubricant or the like can be sufficiently adhered to further suppress the burning or galling.

It is a block diagram which shows one Embodiment of the die-cushion apparatus of this invention in the state attached to the press machine. 2a and 2b are a plan view and a schematic longitudinal sectional view of a sliding frictional force generating mechanism coupled to a mold. It is a block diagram which shows other embodiment of the die-cushion apparatus of this invention. 4a and 4b show still another embodiment of the die cushion device of the present invention. FIG. 4a is a structural view of the die cushion device attached to a press machine, and FIG. 4b is a plan view. 5a and 5b show an application example in which the die cushion of the present invention is used for precision punching, FIG. 5a is a sectional view of a mold, and FIG. 5b is a front view of a punched product. 6a and 6b show still another embodiment of the die cushion device of the present invention, FIG. 6a is a front view showing a state where it is attached to a press, and FIG. 6b is a plan view. 7a and 7b show the main part of the die cushion device of FIG. 6a, FIG. 7a is a front sectional view, and FIG. 7b is a side sectional view. It is a schematic process drawing which shows the operating state of the die cushion apparatus of FIG. 6a. 9a and 9b show still another embodiment of a die cushion device using the frictional force generating mechanism of the present invention, in which FIG. 9a shows a state where the press machine is at the top dead center, and FIG. 9b shows a state where the die is at the bottom dead center. Indicates. It is a graph which shows the effect | action of the die-cushion apparatus of FIG. 9a. 11a and 11b are schematic configuration diagrams of the friction pin and the hub used for the interference fitting sliding element test, FIG. 11c is a detailed view of the friction pin, and FIG. 11d is an enlarged view showing the oil groove. 12a and 12b are a plan view and a front view of the friction pin used in the durability sliding test. 13a and 13b are a plan view and a longitudinal sectional view of the main part of the hub used in the durability sliding test. 14a and 14b are photomicrographs showing the roughness of the sliding portion and non-sliding portion of the friction pin after the durability sliding test, and FIG. 14c is an enlarged view showing the oil groove of the friction pin. 15a and 15b are photomicrographs showing a comparison of the state of the inner surface of the hub before and after the endurance sliding test.

A die cushion device 10 shown in FIGS. 1, 2 a, and 2 b is attached to a press machine 11 and is a normal pressure type air cushion device 12 disposed below the bolster 13, and a lower mold installed on the bolster 13. 14 and a friction die cushion 15 joined to the lower part of the friction die cushion 15. Reference numeral 16 denotes a supply system that supplies and circulates lubricating oil that also serves as a cooling medium to the friction die cushion 15. The left side of FIG. 1 is a state where the slide of the press machine 11 is raised, and the right side is a lowered state. The same applies to FIGS. 3 and 4a. The press machine 11 includes a frame 18, the bolster 13 described above, a slide 19 that moves up and down, and a known slide drive mechanism (not shown) that drives the slide up and down.

  The air cushion device 12 includes a plurality of bellows 20, air (pressurized air) filled therein, a base plate 21 that supports the lower portion of the bellows, a bolt 22 that suspends and fixes the base plate to the bolster 13, and A pipe 23 and a cushion pad 24 fixed to the upper end of the bellows 20 are provided. The cushion pad 24 is guided by a pipe 23 so as to be slidable up and down. The illustration of an air pipe for supplying air to the bellows 20 is omitted.

  In this embodiment, a through hole 26 is formed in the center of the bolster 13, and a cushion pin 27 is slidably passed through the through hole. There may be a plurality of through holes 26 and cushion pins 27 (see FIGS. 4a and 4b). The cushion pin 27 is a component that transmits the cushion force through the bolster 13 and is generally cylindrical. The cushion pin 27 is used for various molds (lower mold 14), and is in contact with the mold but is not coupled. It is only brought into contact with the cushion pad 24. However, you may couple | bond with a metal mold | die or a cushion pad as needed.

As shown in the upper part of FIG. 2b, the lower die 14 includes a die 29 having a predetermined shape of a punch hole 28 and a counter (counter punch) that is slidably accommodated in the punch hole 28 through a minute clearance. 30. A friction die cushion 15 is disposed below the lower mold 14, and the friction die cushion is fixed to the bolster 13 with a bolt or the like (see FIG. 1). The friction die cushion 15 includes a friction pin 31 provided below the counter 30 and a holder 32 that supports the friction pin so as to be movable up and down. The friction pin 31 has a smaller profile than the counter 30 and is usually cylindrical (see FIG. 2a). The counter 30 is fastened to the upper end of the friction pin 31 with a bolt or the like, and the die 29 is fixed to the holder 32 with a bolt or the like. The upper part 31a and the lower part 31b of the friction pin 31 are somewhat smaller in diameter than the intermediate part 31c. The holder 32 includes a hub (hub plate) 33 corresponding to the intermediate portion 31 c of the friction pin 31, and spacers 34 and 35 disposed on the upper side and the lower side, respectively. In order to seal the lubricating oil, it is preferable that the contact surfaces of the hub 33 and the spacers 34 and 35 are sealed with a seal ring or gasket, and the spacers 34 and 35 are fixed to the hub 33 with bolts or the like.

  The hub 33 is formed with a friction hole 36 that is slidable with the intermediate portion 31c of the friction pin 31 and fits in an interference fit state. The intermediate portion 31c of the friction pin 31 and the friction hole 36 constitute a sliding frictional force generating mechanism according to the present invention. An annular or spiral oil groove 37 is formed on the outer peripheral surface of the intermediate portion 31c, the inner surface of the friction hole 36, or both. In the upper spacer 34, an oil reservoir 38 is formed between the guide hole 34 a slidably fitted to the upper portion 31 a of the friction pin 31 and the intermediate portion 31 c and not between the upper portion 31 a of the friction pin 31. An enlarged diameter portion 34b to be formed is formed. Similarly, in the lower spacer 35, the guide hole 35a that is slidably fitted to the lower portion 31b of the friction pin 31 and the intermediate portion 31c of the friction pin are not slidably contacted, and the oil is provided between the lower portion 31b. An enlarged diameter portion 35b that forms the pool 38 is formed. O-ring grooves are formed in the inner surfaces of the guide holes 34a and 35a, and an O-ring 39 is accommodated therein. The upper and lower spacers 34 and 35 are formed with passages 40 and 41 communicating with the oil reservoirs 38 and 38, respectively.

  The intermediate portion 31c of the friction pin 31 and the friction hole 36 are fitted in an interference fit state. That is, in a natural state where the friction pins 31 are not fitted, the diameter of the intermediate portion 31c of the friction pin 31 is larger than the diameter of the friction hole 36 by the tightening allowance. And it shrinks elastically by fitting, and the friction hole 36 expands elastically correspondingly. This is a so-called negative tolerance fit. For example, when the diameter of the intermediate portion 31c and the friction hole 36 is 30 to 50 mm, the tightening margin is preferably about 0.02 to 0.04 mm, particularly about 0.03 mm. When the friction pin 31 is fitted into the friction hole 36 of the hub 33, the friction pin 31 is cooled in advance and thermally contracted until it becomes smaller than the diameter of the friction hole 36, and inserted into the friction hole 36 in that state, and then at room temperature. A “cold fitting” method is used in which it is returned and strongly fitted. Thereby, an interference fit can be performed without damaging the material of the hub 33. However, shrink fitting or press fitting may be used. When press-fitting, a lubricant, particularly lubricating oil, is applied to the friction surface before fitting.

The friction pin 31 is preferably formed of carbon steel, particularly cold die steel such as JIS standard DC53. The polishing and lapping subjected to the surface, and the following arithmetic mean roughness Ra0.2μm except oil groove if there is an oil groove, preferably it finished to come Wamete smooth. Further, the lower limit is preferably set to arithmetic mean roughness Ra of 0.01 μm or more in order to maintain an oil film, and more preferably set to 0.08 μm or more from the viewpoint of ease of processing. Therefore, a range of Ra 0.01 to 0.2 μm, particularly a range of Ra 0.08 to 0.2 μm is preferable. Further, it is preferable to subject the surface to a curing treatment such as a low temperature TiC treatment. The surface hardness is about 55 to 65 on Rockwell C scale (HRC). Similarly, the hub 33 is made of an alloy tool steel such as JIS standard SKD61, and is subjected to polishing and lapping to make the arithmetic average roughness Ra 0.01 to 0.2 μm, particularly Ra 0.08 to 0.2 μm extremely smooth. It is preferable. Furthermore, it is preferable to subject the surface to a curing treatment such as radical nitriding treatment. The surface hardness is about 45 to 49 on the Rockwell C scale (HRC). It is preferable that the friction pin 31 and the hub 33 have a thermal expansion coefficient as close as possible, and in particular, the same ones are combined. As a result, even if the friction pin and the hub are thermally expanded, the friction pin and the hub are similarly expanded, so that the change in the sliding frictional force can be suppressed.

As shown in FIG. 1, a lubricating oil supply system 16 is connected to the passages 40 and 41 of the upper and lower spacers 34 and 35. The supply system 16 includes a supply pipeline 41a extending from the oil tank OT to the lower spacer passage 41, and a return pipeline 40a connected from the upper spacer passage 40 to the oil tank OT. A supply line can be connected to the upper side. Middle suction-filter SF of the supply pipe 41a, the oil pump OP, the oil cooler OC is interposed. The lubricating oil is cooled by the oil cooler OC, and the frictional heat is removed and radiated.

  On the slide 19 of the press machine 11, an upper die 45 for cutting the workpiece W in cooperation with the lower die 14 is attached. The upper die 45 has a punch 46 whose tip is inserted into the punch hole 28 of the die 29, a plate presser 47 that is slidably disposed around the punch, and a spring (upper cushion) that urges the plate presser downward. 48 and a die holder 49 that regulates the lower limit of the vertical movement of the plate presser.

The die cushion device 10 configured as described above functions when the workpiece W is placed on the lower mold 14 and then the slide 19 is lowered to perform the punching process. That is, when the slide 19 is lowered, the plate presser 47 presses the periphery of the work W, and the punch 46 pressurizes the work W downward. At that time, a force (F1 + F2) obtained by adding the urging force F1 of the air cushion device 12 and the frictional resistance F2 of the friction die cushion 15 is applied to the counter 30 upward. Therefore, the workpiece W is pushed downward while being strongly sandwiched between the punch 46 and the counter 30. Furthermore, the periphery of the workpiece W is also strongly sandwiched between the plate presser 47 and the die 29. Thereby, the central portion Wa of the workpiece W is punched from the surrounding Wb.

  Since the central portion Wa and the surrounding Wb of the workpiece W are both pinched from above and below, they are sheared in almost the entire region from the upper surface to the lower surface of the workpiece W (total shearing process). Therefore, as shown in FIG. 5b, a clean shear surface 52 with few sagging (burrs) 51 based on the sag 50 having rounded corners and the clearance between the die and the punch is obtained. And the dimensional accuracy of the extracted part and the remaining hole is high. In addition, the removed product does not receive a strong bending force, so the flatness is high.

When the slide 19 is raised and the punch 46 is raised, the counter 30 tends to be raised by the upward biasing force F1 applied to the air cushion device 12 via the cushion pin 27 and the friction pin 31. On the other hand, the frictional resistance F of the friction die cushion 15 acts to prevent the upward movement of the friction pin 31. Therefore, the counter 30 is increased by the upward lift force of “F1-F”. That is, in this embodiment, the air cushion device 12 and the friction die cushion 15 have a cushioning action when the slide is lowered, and the air cushion device 12 acts as a “return mechanism” for returning the friction pin 31 when the slide is raised.

The friction cushion capacity (friction resistance) F is calculated by the product of the surface pressure p generated between the metals (sliding surfaces) by interference fit, the area where the surface pressure acts, and the friction coefficient μ. The relationship between the tightening allowance δ in the fitting and the generated surface pressure p is expressed by Equation 1.
The friction cushion ability F is a product of the surface pressure p, the friction coefficient μ, and the sliding area S on the sliding surface. Since the sliding area S is π × D ₁ × L, the friction cushion ability F is expressed by Equation 2.
[Equation 2]
F = p × μ × (π × D ₁ × L)
As the friction coefficient μ, a dynamic friction coefficient is employed when the friction pin 31 is moving, and a static friction coefficient is employed until the friction pin 31 starts moving from a stationary state. Where δ: interference, ν ₁ : Poisson's ratio of friction pin, ν ₂ : Poisson's ratio of hub, E ₁ : Young's modulus of friction pin, D ₁ : fitting diameter of friction pin, E ₂ : Young's modulus of hub , D ₂ : the outer diameter of the hub.

The friction coefficient μ varies depending on the viscosity resistance of the lubricating oil, and the viscosity resistance varies depending on the temperature. Furthermore, the diameters of the friction holes and friction pins also thermally expand with temperature. However, since the friction die cushion 15 of FIG. 1 is constantly cooled by the lubricating oil cooled by the oil cooler OC, there is little change, and therefore the frictional resistance does not fluctuate greatly. And since it is sliding of smooth surfaces and is always lubricated with the lubricating oil, seizure and galling of the friction surface can be prevented. In addition to the lubricating oil, the hub 33 may be cooled by forming a cooling oil passage serving as a cooling medium inside the hub 33. In that case, since the passage sectional area of the cooling oil can be increased, the hub can be efficiently cooled. As a passage inside the hub 33, it is preferable that a hub is constituted by a double cylindrical body arranged concentrically with a gap, and the gap is used as a flow path. In that case, not only the passage cross-sectional area is large, but also the contact area with the cooling oil (cooling medium) is large, so the heat transfer efficiency is high.

Die cushion apparatus 55 shown in FIG. 3 includes a friction die cushion 56 substantially the same as the friction die cushion 15 of FIG. 2b, and a knockout mechanism 57 for pushing up the friction pin 31. No air cushion device is provided. An oil supply circuit for supplying lubricating oil to the friction die cushion 56 is not shown.

In the friction die cushion 56 of this embodiment, the upper part 31 a of the friction pin 31 also serves as a counter, and a die 58 that serves also as a spacer is disposed on the hub 33. In other respects, in particular, the configuration of the intermediate portion 31c of the friction pin 31 and the friction hole 36 of the hub 33 is the same as that of the friction die cushion 15 of FIG. The upper mold 45 is the same as the upper mold in FIG. The contour of the punch 46 of the upper die 45 and the contour of the upper portion 31a of the friction pin that also serves as a counter are both circular, and the guide hole 58a formed in the die 58 is also circular. Therefore, it is possible to form an O-ring groove on the inner peripheral surface of the guide hole 58a, accommodate the O-ring therein, and seal between the upper portion 31a of the friction pin 31.

  The knockout mechanism 57 is in contact with a cam 59 rotatably disposed below the bolster 13, a cam drive mechanism (not shown) that rotates the cam in synchronization with the vertical movement of the slide, and an outer peripheral surface of the cam 59. A cam follower 60 that moves up and down, and a knockout pin 61 that transmits the up and down movement of the cam follower to the friction pin 31. As the cam 59, a plate cam provided with a projecting portion 62 projecting smoothly on a part of a disc is employed. Another form of cam such as a groove cam may be used. The knockout pin 61 is slidably provided in the through hole 26 formed in the bolster 13. The cam 59 can be rotationally driven by transmitting the rotational motion of the crankshaft that drives the slide of the press machine 11 through the connecting shaft, for example.

Further, the cam 59 can be driven to rotate independently by a motor provided separately from the crankshaft. At that time, a control device for detecting the operating state of the press machine 11 and controlling the motor is provided. The use of a servo motor as the motor is preferable because the timing of the vertical movement of the knockout pin 61 can be set freely. Instead of the cam mechanism, other mechanisms such as a screw mechanism or a rack-pinion mechanism that convert rotation into a reciprocating linear motion can be employed. The mechanism for returning these friction pins to their original positions includes the friction die cushion 15 independent of the mold as shown in FIGS. 1 and 2b, the friction die cushion 56 integrated with the mold of FIG. 3, FIG. 4a, It can also be applied to the friction die cushion used in the drawing die of FIG. 4b.

Since the die cushion device 56 of FIG. 3 does not include an air cushion device, when the slide 19 descends, the force that sandwiches the workpiece W between the punch 46 and the counter punch (here, the upper portion 31a of the friction pin) is a friction die. Only the cushion 56 bears. Further, even when the frictional force is not strong, there is no urging force to rise, so that it can be used as a cushion having a locking mechanism, and the timing for taking out the punched product from the die can be freely set.

The die cushion device 63 shown in FIGS. 4 a and 4 b includes an air cushion device 12 and a friction die cushion 64. A die-type (deep-draw type) is used as the mold, and the upward biasing force of the die cushion device is used for holding the workpiece against the heel. The lower die 65 has a base 66, a punch 67 arranged so that the upper part protrudes at the center thereof, a cushion ring 68 provided so as to be movable up and down with respect to the base 66 so as to surround the punch, and below the cushion ring. And four spacer pins 69 that support the cushion ring. The upper die 70 that cooperates with the lower die 65 includes a die 71 that fits the punch 67 with the workpiece W interposed therebetween, and a die plate 72 that holds the die.

  The cushion ring 68 of the lower die 65 is slidably accommodated in an annular groove 73 provided on the upper surface of the base 66, and four spacer pins 69 penetrate from the bottom of the annular groove 73 to the lower surface of the base 66. Is slidably accommodated in the hole 66a. As shown in FIG. 4b, four spacer pins 69 are arranged at equal intervals in the circumferential direction.

The friction die cushion 64 includes four friction pins 31 arranged concentrically below each spacer pin 69, a hub 33 that holds the friction pins in a slidable and tightly fitted state, and And spacers 34 and 35 disposed above and below the hub. The friction pin 31, the hub 33, and the upper and lower spacers 34 and 35 are the same as the friction die cushion 15 shown in FIGS. 1 and 2b except that the friction pin 31 is four and the friction holes are four.

Further, the friction die cushion 15 shown in FIG. 2B also has a small diameter at the upper part 31a and the lower part 31b of the friction pin 31 and generates frictional resistance by sliding friction between the outer peripheral surface of the intermediate part 31c and the inner surface of the friction hole 36 of the hub 33. It is the same. The bolster 13 is formed with through holes 26 at the center front and rear, and at the left and right, and a cushion pin 27 is accommodated in each through hole 26 so as to be vertically movable. In addition, in consideration of the versatility of the position of the cushion pin, a large number of through holes 26 formed in the bolster 13 may be formed in a grid pattern, and a large rectangular opening may be provided instead of the through hole. There is.

  FIG. 5a shows the operating state of the punching die 75 which is almost the same as that in FIG. 1, particularly at the start of the punching of the workpiece W. In this state, the workpiece W is sandwiched between the plate presser 47 and the upper surface of the die 29, and the lower end of the punch 46 bites into the upper surface of the workpiece W somewhat. Similarly, the corner of the punched hole 28 of the die 29 bites into the lower surface of the workpiece W. The clearance between the punch hole 28 and the punch 46 is as narrow as about 0.01 mm to 0.03 mm. When the punch 46 is further lowered from this state, the workpiece W is sheared substantially at a right angle to the workpiece between a portion corresponding to the periphery of the lower surface of the punch 46 and a portion corresponding to the corner of the punch hole 28 of the die. Therefore, precision shearing (fine blanking) with less sagging and burrs is performed (see FIG. 5b).

The die cushion device 76 shown in FIG. 6a includes a friction die cushion 77 and a reversing mechanism 78 that reverses the entire friction die cushion 77 every time it is processed. The friction die cushion 77 is disposed so as to extend in the left-right direction in the housing 79, and a cylindrical hub 80 that is rotatably supported around its own axis, and friction formed in the diameter direction of the hub. A friction pin 82 is slidably fitted in the hole 81 and fitted in an interference fit state. The housing 79 is formed with a cylindrical, semicircular or fan-shaped space 83 (see FIGS. 7a and 7b) in order to avoid interference with the portion of the friction pin 82 protruding from the hub 80. The material of the hub 80 and the friction pin 82 and the dimensional relationship between the friction hole 81 and the friction pin 82 are the same as those of the friction die cushion 15 of FIG.

  At the center of the hub 80, a flow path or oil reservoir 84 for circulating lubricating oil that also serves as a cooling medium is formed. The oil reservoirs 84 open at both ends of the hub 80 and are closed by caps 85, respectively. The oil reservoir 84 is further connected to the supply pipeline 41a and the return pipeline 40a of the lubricating oil supply system via a rotary joint 86 attached to the cap 85, respectively. One end of the hub 80 (on the right side in FIG. 6a) protrudes greatly from the housing 79, and a reversing mechanism 78 is provided around it. In this embodiment, a gear or pinion 87 is fixed around the hub 80, and is driven to reciprocate by a motor and a speed reducer (not shown). You may rotate by half rotation in the same direction. Reciprocating reversal driving can also be performed by a rack using a slide driving mechanism of an air cylinder or a press as a driving source.

  The die cushion device 76 shown in FIG. 6a can be used in a drawing mold similar to the embodiment of FIG. 4a. The lower die 65 is disposed on the housing 79, and the upper die 70 is attached to the slide of the press machine. A hole 74 extending upward from the space 83 is formed in the housing 79. The lower die 65 has a base 66, a punch 67, and a cushion ring 68, and the cushion ring 68 is supported by four cushion pins 68a. The cushion pin 68a is constantly biased upward by a lift spring 68b (see FIG. 7a). The cushion pin 68a is accommodated in a hole 66a formed in the base 66 of the lower mold 65 so as to be movable up and down. These holes are provided at portions corresponding to the holes 74 of the housing 79, and are usually arranged evenly in the circumferential direction. The upper mold 70 is similar to the upper mold of FIG.

  As shown in FIG. 6b, two hubs 80 are provided so as to extend in the left-right direction in parallel with each other. The friction pins 82 supported by the hubs 80 and the cushion pins 68a are arranged concentrically up and down. Both ends of the friction pin 82 are formed in a substantially convex spherical shape, and the lower end of the cushion pin 68a is formed in a substantially concave spherical surface corresponding to the spherical surface. Thereby, the escape of the cushion pin 68a can be minimized, and the position of the cushion pin 68a is stabilized.

  In the die cushion device 76 configured as described above, the friction pin 82 has a die (see FIG. 6a) through the workpiece and the cushion pin 68a in a state where the upper end protrudes from the hub 80 (see S1, FIG. 8, upper left). 71) and shift downward (see S2 in FIG. 8, upper right). As a result, the lower end of the friction pin 82 protrudes downward from the lower surface of the hub 80. Next, after the slide of the press machine is raised and the die 71 is raised (S3), the hub 80 rotates 180 degrees (S4, S5). As a result, the end of the friction pin 82 protrudes from the upper surface of the hub 80. Therefore, the workpiece can be processed while receiving the cushioning force by the die 71 again.

  When reversing from this state, it may be rotated in the same direction or in the opposite direction. By causing the protruding side to rotate in the opposite direction with respect to the other hub 80, it is possible to narrow the space between the cores. As a driving source of the hub 80, in addition to the motor described above, a gas / liquid cylinder, a vertical movement of a slide, a rotation of a crankshaft, or the like may be used. Lubricating oil is supplied to the gap between the friction pin 82 and the hub 80 from an oil reservoir 84 provided at the center of the hub 80. Lubricating oil is supplied to the oil reservoir 84 from the supply pipe 41a and goes out from the return pipe 40a. Since the supply pipe 41a is filled with low-temperature lubricating oil, lubrication and cooling can be performed simultaneously with the lubricating oil.

In embodiments such as FIGS. 1-5, the urging force of the air cushion device is used in preparation for the next processing (FIGS. 1 and 4a), or the friction pin is returned to the original position using a knockout mechanism. I have to. On the other hand, in the die cushion device 76 of FIG. 6a, the friction die cushion 77 is reversed so that the friction pin 82 is returned to the original state without changing the relative positional relationship between the friction pin 82 and the hub 80. be able to. Therefore, energy efficiency is high. Although FIG. 6a demonstrated the die-cushion apparatus using the friction die cushion used for a drawing die , it can also be used for the precision cutting die similar to FIG. In that case, one cushion pin is sufficient.

  The die cushion device 90 shown in FIG. 9a applies pressure to the cylinder 91 disposed in the lower part of the press machine 11, the piston 92 accommodated in the cylinder so as to be movable up and down, and the hydraulic oil in the cylinder 91, A so-called relief-type cushion device comprising a communication path 93 for guiding hydraulic oil to the outside when the piston 92 descends, and a hydraulic circuit 94 that exerts back pressure on the hydraulic oil discharged to the outside to exert a cushioning force. is there. The communication path 93 includes an annular space 93a formed on the outer periphery of the lower portion of the cylinder 91, a plurality of communication holes 93b communicating with the inside of the cylinder and the annular space, and a communication path provided in the frame 18 or the bolster of the press machine. 93c. The hydraulic circuit 94 is provided with an oil pump OP that supplies hydraulic oil to the cylinder 91 and a relief valve LV that releases the hydraulic oil when the inside of the cylinder 91 exceeds a certain pressure.

The die cushion device 90 further includes a frictional force cushion portion 95 that is slidable on the inner surface of the cylinder 91 with the outer periphery near the lower end of the piston 92 and that is fitted in an interference fit. Is provided. The frictional force cushion part 95 has an inner diameter smaller than that of the other parts by the tightening allowance. The frictional force cushion portion 95 and the piston 92 are friction die cushions that exert a cushioning force only at a specific position near the bottom dead center of the press machine.

  In this relief type cushion device 90, when the counter or cushion ring is pushed downward by the upper die to process the workpiece, the hydraulic oil in the cylinder 91 escapes to the hydraulic circuit 94 side via the communication path 93 (FIG. 9b). reference). At that time, the resistance of the hydraulic oil passing through the communication path 93 and the resistance when passing through the relief valve LV are cushioning forces. The resistance force can be preset by the relief valve LV of the hydraulic circuit 94. Before the piston 92 reaches the frictional force cushion part 95, the cushioning action is performed only with the relief pressure, and when the piston 92 reaches the frictional force cushioning part 95, a cushioning action combining the relief pressure and the frictional force is achieved.

When the slide moves up (see the one-dot chain line in FIG. 10), hydraulic oil is supplied from the hydraulic circuit 94 into the cylinder 91, and the piston 92 is raised. Frictional force at this time is the resistance to hinder raise the piston 92, unnecessary frictional resistance is eliminated when leaves the frictional force cushion unit 95.

  By the way, in the relief-type cushion device 90, the viscosity resistance increases as the flow velocity increases, and decreases as the flow velocity decreases, so that the cushioning capability has speed dependency. Therefore, as shown by the solid line and the alternate long and short dash line in FIG. 10, there is a pressure override characteristic in which the cushioning ability is reduced near the bottom dead center where the stroke speed is reduced. In addition, if the relief valve passage area is reduced by a servo valve or the like, the override characteristic is eased, but a phenomenon occurs in which the product is pushed back by the cushion residual pressure after the bottom dead center.

Figure 9a, the die cushion apparatus 90 in FIG. 9b, since the combination of friction die cushion to the hydraulic cylinder apparatus comprising a cylinder 91 and a piston 92 as corresponding of these phenomena, a decrease in the cushioning force by overriding characteristic near the bottom dead center It is possible to compensate and maintain a stable cushioning ability to the bottom dead center (see the broken line in FIG. 10).

  In the above-described embodiment, the frictional force generating mechanism is used for a die cushion of a press machine. However, the frictional force generating mechanism of the present invention is not limited to these, and a friction damper that attenuates vibration by sliding frictional resistance, It can be applied to various devices such as a knockout overload prevention device and a press overload protector device. In the above-described embodiment, the case where the hub is cooled with the lubricating oil or the cooling oil has been described. However, the hub may be cooled with another cooling medium such as water or air.

[Test 1: interference fit sliding: element test]
Next, an element test of interference fit sliding performed to verify the practicality and effect of the sliding frictional force generating mechanism of the present invention will be described. The friction pins (shaft members) 96 and 98 of the first embodiment used for this test have a schematic shape shown in FIGS. 11a and 11b. Specifically, it has the shape and dimensions of FIG. The unit of the number is mm. “Φ” in the drawing is a symbol indicating a diameter. The material of the friction pins 96 and 98 is S45C (JIS), and Hs is 35 ± 3 due to tempering during quenching and tempering. On the other hand, the material of the hub 97 was S45C raw material (basically no heat treatment). The inner diameter of the hub (hole member) 97 is slightly smaller (about 0.03 mm) than the outer diameter of the friction pins 96 and 98 . The outer diameter of the hub is 64 mm and the height is 51 mm. The hub 97 is not provided with an oil groove.

The friction pins 96 and 98 were put in liquid nitrogen and cooled, and after boiling stopped , the friction pins 96 and 98 were inserted into the hole 97a of the hub 97, returned to room temperature, and brought into an interference fit state. Then, the friction pin was pressed in the axial direction by a press machine and pulled out from the hub 97, and the surface condition was observed. Five types of samples were prepared, and the above-mentioned interference fit and withdrawal were repeated 6 times for each sample. In the first test, the friction pin 96 having no oil groove of FIG. 11a is used, and the friction pin 98 having an oil groove ( reference numeral 98a in FIG. 11d) is additionally used as shown in FIG. It was.

  As shown in FIG. 11d, the oil groove 98a has an arc shape with a radius of 0.2 mm and a depth of 0.03 mm. As shown in FIG. 11c, the oil grooves 98a are formed in a spiral shape at intervals of 1.2 mm (Lead) in the axial direction. A large number of annular oil grooves may be arranged and connected by oil grooves in a direction parallel to the axis. In either case, the cylindrical surface between the oil grooves 98a is the sliding surface 98b.

  The number of samples in the test is the sample number. 1-No. There are 5 types. Of these, No. 1, no. 3, no. In No. 5, the friction pins 96 and 98 were cooled with liquid nitrogen to about −180 ° C., and then inserted into the hub 97. No. 2, No. No. 4 employs a shrink fitting method in which the hub 97 is heated to 150 ° C. and then the friction pins 96 at room temperature are inserted.

  In the test, six cold fitting / extraction (extraction) tests were performed, and the surface roughness Ra before and after the test was measured. Furthermore, the load at the time of each cold fitting / extraction was measured. Table 1 shows the surface roughness Ra of the friction pins 96 and 98 and the hub 97 before and after the test. In Table 1, the generated surface pressure is reversely calculated based on the load applied at the time of drawing and the tightening allowance, and the static friction coefficient μ calculated reversely at the time of extraction 1 to 6 times is also described. The surface roughness measuring instrument is a roughness measuring instrument Surf Test SJ301 manufactured by Mitutoyo Corporation. The unit of the surface roughness Ra is μm.

As can be seen from Table 1, sample no. 1 surface roughness Ra (pin: 0.12μm, hub:. 0 18μm) and sample No. 5. In the case of surface roughness Ra (pin: 0.19 μm, hub: 0.20 μm), the coefficient of friction decreases as the number of tests increases, and after six tests, the surface roughness is higher than before the test. It was a low value. That is, the surface was smooth by the sliding test.

  On the other hand, sample Nos. 1 and 2 having a surface roughness Ra of the friction pins 96 and 98 of 0.13 μm and a surface roughness Ra of the hole 97a of the hub 97 of 0.21 μm. In the case of 3, the friction coefficient μ increased as the number of sliding operations increased, and the friction pin 98 was galling during the fourth sliding test, so the test was stopped (***). The reason is not clear, but when the surface roughness is large, there is a part that hits partly strongly, and there is a possibility that the lubricating oil did not rotate sufficiently. Sample No. 2 (*), No. 2 In the case of the sample with 4 (**) shrink-fit, since the seizure occurred immediately after the start of the test, the test could not be performed substantially. In the case of shrink fitting, there is a possibility that a uniform interference fit has not been achieved or the surface lubricating film has been destroyed.

[Test 2: Measurement of diameter and surface roughness]
Next, the friction pin 99 and the hub 100 of the second embodiment shown in FIGS. 12 and 13 were prepared, and the surface roughness and the outer diameter at the time of preparation and after the test were measured. The outer diameter of the sliding portion of the friction pin 99 is about 35.035 mm and the length is 64 mm. The sliding portion was provided with a semicircular oil groove 99a having a radius of 0.4 mm shown in FIG. Between the oil grooves 99a is a sliding surface 99b. In the region near the oil groove 99a of the sliding surface 99b, a loose tapered flank 99c was formed.

  The surface hardness of the inner surface of the hole 100 a of the hub 100 is lower than the surface hardness of the friction pin 99. Specifically, the friction pin 99 has an outer diameter of 35.035 (see Table 2), and the material is DC53 (die steel manufactured by Daido Steel Co., Ltd., SKD11 (JIS) equivalent). By returning, the surface hardness was set to HRC (Rockwell hardness C scale) = 60 ± 2. Further, low-temperature TiC treatment (titanium carbide coating treatment) was performed.

  The hub 100 has an inner diameter of about 34.998 mm, and is made of SKD61. The hardness is HRC = 47 ± 2 by quenching and high-temperature tempering. Furthermore, radical nitriding treatment was performed. The hole 100a of the hub 100 has the shape and dimensions shown in FIGS. 13a and 13b. There is no oil groove.

  Table 2 shows the measured values of the surface roughness and the outer diameter when the friction pin was created. The measurement points of the surface roughness are the positions I, II, and III in the axial direction of FIG. 12b with respect to the positions A and B in the circumferential direction of FIG. The measuring instrument is a surface roughness measuring instrument Surftest SJ-301 manufactured by Mitutoyo Corporation. The measurement points of the outer diameter are the positions I, II, and III in the axial direction of FIG. 13b between A and C and B and D in FIG. 13a, and there are six places as a whole. The measuring instrument is a micro gauge manufactured by Mitutoyo Corporation, and its unit is μm.

  The measurement results of the surface roughness of the inner surface of the hole 100a when the hub 100 is created are shown on the left side of Table 3. The number of measurement positions was 6 in total in the axial positions I, II, and III in FIG. 13b for each of the circumferential positions A and B in FIG. 13a. The measurement result of the inner diameter when the hub 100 is created is shown on the right side of Table 3. The measurement points are the axial positions I, II, and III with respect to the circumferential positions AC and BD, and there are six positions as a whole. The inner surface of the hole 100a was rough as shown in the micrograph of FIG. 15a.

  The friction pin 99 was put in liquid nitrogen, cooled to −180 ° C., inserted into the hole 100 a of the hub 100, and cooled to fit at room temperature. Thereafter, while supplying lubricating oil, the friction pin 99 was reciprocally slid by applying axial pressure and pulling force. The temperature of the lubricating oil was maintained at 20 ° C., and lubrication was performed at a flow rate of 100 cc / min and a pressure of 0.5 MPa. Even when the number of sliding operations exceeded 600,000, no galling or seizure occurred. It was found that the sliding friction resistance in this dimension was 62 kN to 64 kN, with an average of 63 kN, and less variation.

  After the test, the friction pin 99 was removed from the hub 100, and the surface roughness and the fitting diameter of the surface of the friction pin 99 and the inner surface of the hole 100a of the hub were measured. The measurement results are shown in Tables 4 and 5.

  As can be seen by comparing Tables 2 and 4 and Tables 3 and 5, respectively, the surface roughness and sliding part diameter of the friction pin 99 and the hub 100 are almost the same before and after the 600,000 sliding tests. There wasn't. That is, the surface roughness Ra of the friction pin 99 before and after the test is not changed except that the surface roughness Ra is increased by 0.01 μm at the measurement points B and III, and it can be determined that there is substantially no wear. Further, the outer diameter does not change except that it decreases by 0.001 mm between BD and II and increases by 0.001 mm between BD and III, and it can be determined that there is substantially no wear.

  In the case of the hub 100, the surface roughness Ra is not changed except that the surface roughness Ra is decreased by 0.01 μm at the measurement points A and I, and the inner diameter is increased by 0.001 mm at positions I and III between AC. This indicates that even if sliding is repeated at a high surface pressure, if the initial surface roughness and the finishing accuracy of the sliding part diameter are sufficiently high, the durability is sufficiently high and practical.

[Observation of pin surface condition]
FIGS. 14a and 14b show micrographs of the sliding surface 99b and the flank 99c after the 600,000 sliding tests of the friction pin 99 of Example 2, respectively. The magnification is 3000 times. Similarly, micrographs of the hub 100 of Example 2 at the initial stage and after 600,000 sliding tests are shown in FIGS. 15a and 15b, respectively. The magnification is 5000 times. As can be seen from these micrographs, the friction pin 99 and the hub 100 have no galling on the surface even after 600,000 sliding tests.

  Further, as can be seen by comparing FIG. 14a and FIG. 14b, the sliding surface 99b of the friction pin 99 has less roughness and unevenness than the flank 99c. Similarly, as can be seen by comparing FIG. 15a and FIG. 15b, it can be seen that the surface condition (surface roughness) after the sliding test of the hub 100 is equal to the initial value or is improved (smoothed). . This is considered that the surface was lapped and smoothed by repeated sliding under sufficient lubrication.

10 Die cushion device 11 Press machine 12 Air cushion device 13 Bolster 14 Lower mold 15 Friction die cushion 16 Lubricating oil supply system 18 Frame 19 Slide 20 Bellows 21 Base plate 22 Bolt 23 Pipe 24 Cushion pad 26 Through hole 27 Cushion Pin 28 Punching hole 29 Die 30 Counter 31 Friction pin 31a Upper part 31b Lower part 31c Intermediate part 32 Holder 33 Hub 34, 35 Spacer 34a, 35a (Spacer) Guide hole 34b, 35b Expanded part 36 Friction hole 37 Oil groove 38 Oil reservoir 38 39 O-ring 40 and 41 passages 41a supply line 40a return line OT oil tank SF suction-filter OP oil pump OC oil cooler 45 upper die W workpiece 46 punch 47 blank holder 48 spring 49 Ihoruda F1 air cushion frictional resistance 50 sag 51 burr 52 shearing surface 55 a die cushion device of the apparatus force F2 friction die cushion force of 56 Friction die cushion 57 knockout mechanism 58 die 58a (dies) guide holes 59 cam 60 the cam follower 61 knockout pin 63 Die cushion device 64 Friction die cushion 65 Lower die 66 Base 66a (base) hole 67 Punch 68 Cushion ring 68a Cushion pin 69 Spacer pin 70 Upper die 71 Die 72 Die plate 73 Annular groove 74 (housing) hole 75 Die 76 die cushion device 77 friction die cushion 78 reversing mechanism 79 housing 80 hub 81 frictional openings 82 the friction pin 83 cavity 84 oil reservoir 85 cap 86 rotary joint 87 pinion 68 Cushion pins 68b lift spring 90 die cushion apparatus 91 cylinder 92 piston 93 communicating path 93a annular space 93b communicating hole 93c communicating passage 94 hydraulic circuit 95 friction cushioning portion 96 the friction pin (first embodiment)
97 Hub 97a Hole 98 Friction pin (after oil groove processing)
98a Oil groove 98b Sliding surface 99 Friction pin (second embodiment)
99a Oil groove 99b Sliding surface 99c Flank 100 Hub 100a Holes A, B, C, D Circumferential positions I, II, III Axial positions

Claims (9)

A metal hole member having a hole;
A metal shaft member that is axially slidably fitted into the hole of the hole member and repeatedly and axially slides in an interference fit state ;
Between them, it consists of an oil supply mechanism that supplies lubricating oil that also serves as a cooling medium that cools frictional heat due to sliding ,
And fitted in a state interference fit with said bore and the shaft member,
The surface roughness of the inner surface of the hole and the surface of the shaft member is Ra 0.01 to 0.2 μm,
An oil groove for passing the lubricating oil is formed in at least one of the inner surface of the hole of the hole member and the outer surface of the shaft member,
A sliding frictional force generating mechanism , wherein the oil supply mechanism includes a supply pipe for supplying lubricating oil to one end of the oil groove and a return pipe for returning the lubricating oil from the other end of the oil groove . At least one of the hole member and the shaft member is formed with a passage for supplying the lubricating oil to one end side of the oil groove and a passage for returning the lubricating oil from the other end side of the oil groove, which is different from the supply passage. The sliding frictional force generating mechanism according to claim 1. The sliding frictional force generating mechanism according to claim 1, wherein a passage for flowing another cooling medium different from the lubricating oil is formed in at least one of the hole member and the shaft member. The sliding frictional force generating mechanism according to any one of claims 1 to 3, wherein both the hole member and the shaft member are made of carbon steel, and a hardened surface treatment is applied to at least one sliding surface. A metal hole member having a hole, a metal shaft member fitted in the hole of the hole member so as to be axially slidable, and an oil supply mechanism for supplying a lubricating oil serving as a cooling medium therebetween A sliding frictional force generating mechanism in which the hole and the shaft member are fitted in an interference fit state ,
A return mechanism for returning the pushed-in shaft member to a state before being pushed,
A die cushion device for a press machine that uses the sliding frictional force generation mechanism as a reaction force or resistance force generation source for press working to clamp a workpiece. A metal hole member having a hole, a metal shaft member fitted in the hole of the hole member so as to be freely slidable in the axial direction, and an oil supply mechanism for supplying lubricating oil serving as a cooling medium between them; A sliding frictional force generating mechanism in which the hole and the shaft member are fitted in an interference fit state ;
Base and
A punch placed in the center of the base,
A cushion ring that is automatically and vertically arranged to surround the base;
It consists of multiple spacer pins that support the cushion ring,
The spacer pin is supported by the shaft member of the sliding frictional force generating mechanism,
Mold for press machine. A metal hole member having a hole, a metal shaft member fitted in the hole of the hole member so as to be axially slidable, and an oil supply mechanism for supplying a lubricating oil serving as a cooling medium therebetween A sliding frictional force generating mechanism in which the hole and the shaft member are fitted in an interference fit state ,
A reversing mechanism that reverses the sliding frictional force generating mechanism,
The hole of the hole member of the sliding frictional force generation mechanism is a through hole, and the length of the shaft member is longer than the hole,
When the reversing mechanism reverses the sliding frictional force generating mechanism for each press of the press machine, the pushed shaft returns to the position before pushing,
A die cushion device using the sliding frictional force generating mechanism as a reaction force or resistance generating source for press working for clamping a workpiece. A relief type die cushion device that includes a hydraulic cylinder composed of a cylinder and a piston, and that exerts a cushioning force due to the resistance of hydraulic oil coming out of the hydraulic cylinder,
A metal hole member having a hole, a metal shaft member fitted in the hole of the hole member so as to be freely slidable in the axial direction, and an oil supply mechanism for supplying lubricating oil serving as a cooling medium between them; A sliding frictional force generating mechanism in which the hole and the shaft member are fitted in an interference fit state;
Before one of the outer surface of the carboxymethyl Linda inner surface and the piston, a press machine configured to have a relief-type die cushion apparatus of the sliding frictional force generating mechanism in the sliding contact portion between at around the bottom dead center of the. The manufacturing method of the sliding frictional force generation mechanism according to any one of claims 1 to 4, wherein the hole member and the shaft member are fitted by cold fitting.