Manufacturing method of wet friction plate

Abstract

To provide a manufacturing method of a wet friction plate capable of improving holding property of lubricant in a fine groove formed with a laser beam.SOLUTION: A manufacturing method for a wet friction plate 200 comprises, after a friction material 210 is manufactured by papermaking in a first step, forming a fine groove 211 on the friction material 210 in a second step. In the friction material 210, a thermosetting resin is manufactured in a semi-cured state. The fine groove 211 is formed in a V shape in cross section by a laser beam. Next, in a third step, the friction material 210 is arranged on the core metal 201 via an adhesive made of a thermosetting resin. Next, in a fourth step, the friction material 210 is pressed while applying heat thereto, to crush the fine groove 211, to form irregularities on the inner surface 212 in the groove and completely cure the thermosetting resin.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method of making a wet friction plate for use in a lubricating oil. [Background technology]

[0002] Conventionally, vehicles such as four-wheeled automobiles and two-wheeled automobiles are equipped with wet-type multi-plate clutch devices to transmit or cut off the rotational driving force of a prime mover such as an engine to a driven body such as a wheel. In general, wet-type multi-plate clutch devices transmit or cut off the rotational driving force by pressing two plates, which are arranged opposite each other in lubricating oil, against each other.

[0003] In this case, one of the two plates is configured as a wet friction plate in which a friction material is provided along the circumferential direction on the surface of a flat annular core metal. For example, the following Patent Document 1 discloses a laser processing method and a laser processing device for a friction plate (hereinafter referred to as a "wet friction plate") in which a concave portion consisting of minute irregularities and grooves (hereinafter referred to as a "microgroove") is formed on the surface of the friction material by a laser beam. As a result, the wet friction plate can promote the flow of lubricating oil in the microgroove compared to conventional cutting processing by sharpening the processed end of the microgroove by the laser beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-133242 A

[0005] However, in the laser processing method and laser processing apparatus for a wet friction plate described in the above Patent Document 1, while the flowability of the lubricating oil is promoted, the retention of the lubricating oil is low, and the cooling performance of the wet friction plate by the lubricating oil is reduced.

[0006] The present invention has been made to address the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a wet friction plate that can improve the retention of lubricating oil in fine grooves formed by laser light. Summary of the Invention

[0007] In order to achieve the above object, the present invention is characterized in that it is a manufacturing method for a wet friction plate in which a friction material is provided along the circumferential direction on the surface of a core metal formed in a flat ring shape, and includes a fine groove forming process in which a laser beam is irradiated while being displaced relative to the friction material to form concave fine grooves on the surface of the friction material, and a crushing process in which pressure is applied to the friction material to crush and deform the fine grooves.

[0008] According to the features of the present invention thus configured, the method for manufacturing a wet friction plate uses a laser beam to form microgrooves, and then presses the friction material with the microgrooves formed therein to crush the microgrooves, thereby improving the retention of lubricating oil. In this case, the microgroove is formed in a shape in which the groove width is 10 μm or more and 1000 μm or less, and the cross-sectional shape is 10 μm or more and 1000 μm or less in depth, and the groove width is 10 μm or more and 1000 μm or less, and the groove width is 10 μm or more and 1000 μm or less in depth ...

[0009] Another feature of the present invention is that the method for manufacturing the wet friction plate further includes a friction material arranging step of arranging a friction material on the core bar, and the fine groove forming step is performed prior to the friction material arranging step.

[0010] According to another feature of the present invention configured in this manner, in the manufacturing method of the wet friction plate, the fine groove forming step is performed before the friction material arrangement step, so that the fine grooves can be formed with high precision more easily than in the case where the fine grooves are machined into the friction material on the core bar.

[0011] Another feature of the present invention is that in the method for producing a wet friction plate, the crushing step is performed on the friction material arranged on the core metal.

[0012] According to another feature of the present invention configured in this manner, in the method for manufacturing a wet friction plate, the crushing step is performed on the friction material arranged on the core bar. Therefore, compared to the case where the crushing step is performed at a location other than the core bar, the crushing step can also serve as a step of attaching the friction material to the core bar, thereby reducing the number of steps and enabling the wet friction plate to be manufactured efficiently.

[0013] Another feature of the present invention is that the method for manufacturing the wet friction plate further includes a friction material arranging step of arranging a friction material on a core bar, the fine groove forming step being performed on the friction material arranged on the core bar, and the crushing step being performed on the friction material arranged on the core bar.

[0014] According to another feature of the present invention configured in this manner, in the manufacturing method of the wet friction plate, the fine groove forming step and the crushing step are performed on the friction material placed on the core bar, so that the fine grooves can be formed with high precision at precise positions on the core bar.

[0015] Another feature of the present invention is that the method for manufacturing a wet friction plate further includes a friction material manufacturing step of manufacturing a paper sheet in which an aggregate of countless fibers is impregnated with a thermosetting resin as a friction material, and the pressing step includes pressing the friction material while applying heat.

[0016] According to another feature of the present invention configured in this manner, the method for manufacturing a wet friction plate can manufacture a wet friction plate by applying heat to a friction material made of a paper sheet in which an aggregate of countless fibers is impregnated with a thermosetting resin, thereby suppressing springback of the pressed friction material and precisely crushing the fine grooves.

[0017] Another feature of the present invention is that in the method for manufacturing the wet friction plate, the friction material manufacturing step is to manufacture a paper body in a semi-cured state in which the thermosetting resin has been cured to a degree that does not result in complete curing, and the pressing step is to completely cure the thermosetting resin in the semi-cured state by applying heat to the friction material.

[0018] According to another feature of the present invention configured as described above, in the manufacturing method of the wet friction plate, the semi-cured thermosetting resin is completely cured by applying heat to the friction material in the crushing process, so that the springback of the pressed friction material is suppressed and the fine grooves are crushed with high precision to manufacture the wet friction plate. In addition, in this manufacturing method of the wet friction plate, since the thermosetting resin is in a semi-cured state, the pressure for pressing the friction material can be lowered compared to the case of pressing a friction material with a completely cured thermosetting resin.

[0019] Another feature of the present invention is that in the method for manufacturing the wet friction plate, the friction material arranging step comprises: Friction material is attached via adhesive The pressing step is to press the friction material to attach it to the core metal.

[0020] According to another feature of the present invention configured in this manner, the method for manufacturing a wet friction plate involves placing an adhesive between a core bar and a friction material and pressing the friction material to attach the friction material onto the core bar, so that crushing of the fine grooves and attachment of the friction material can be performed simultaneously, thereby improving work efficiency. [Brief description of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view showing an overall configuration of a wet multi-plate clutch device provided with wet friction plates according to the present invention. [Diagram 2] 2 is a plan view showing the outline of the external configuration of a wet friction plate according to the present invention which is incorporated in the wet multi-plate clutch device shown in FIG. [Diagram 3]3 is a partially enlarged cross-sectional view showing the configuration of fine grooves formed in a friction material of the wet friction plate shown in FIG. 2. [Figure 4] 4 is a flowchart showing a manufacturing process of the wet friction plate according to the present invention. [Diagram 5] 5 is a side view showing a schematic outline of the configuration of a laser processing device used in a fine groove forming step in the manufacturing process of the wet friction plate shown in FIG. 4. [Figure 6] 6 is a plan view showing a long friction material on which fine grooves are formed by the laser processing apparatus shown in FIG. 5. [Figure 7] 6 is a partially enlarged cross-sectional view showing the configuration of a fine groove formed by the laser processing apparatus shown in FIG. 5. [Figure 8] 5 is a side view showing a schematic outline of the configuration of a hot press processing device used in a crushing step of fine grooves in the manufacturing process of the wet friction plate shown in FIG. 4. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of a method for manufacturing a wet friction plate according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an outline of the overall configuration of a wet multi-plate clutch device 100 equipped with a wet friction plate 200 according to the present invention. FIG. 2 is a plan view showing an outline of the external configuration of the wet friction plate 200 according to the present invention equipped in the wet multi-plate clutch device 100 shown in FIG. Note that each figure referred to in this specification is shown in a schematic manner, such as by exaggerating some of the components, in order to facilitate understanding of the present invention. For this reason, the dimensions and ratios between the components may differ.

[0023] This wet-type multi-plate clutch device 100 is a mechanical device for transmitting or cutting off the driving force of an engine (not shown), which is the prime mover in a two-wheeled automobile (motorcycle), to wheels (not shown), which are the driven bodies, and is disposed between the engine and the transmission (not shown).

[0024] (Configuration of wet multi-plate clutch device 100) The wet multi-plate clutch device 100 includes a housing 101 made of an aluminum alloy. The housing 101 is formed in a cylindrical shape with a bottom, and is a member that constitutes a part of the casing of the wet multi-plate clutch device 100. An input gear 102 is fixed to the left side surface of the housing 101 in the figure by a rivet 102b via a torque damper 102a. The input gear 102 is rotated by meshing with a drive gear (not shown) that is rotated by the engine. A plurality of clutch plates 103 (eight in this embodiment) are held on the inner peripheral surface of the housing 101 by spline fitting in a state in which they can be displaced along the axial direction of the housing 101 and can rotate integrally with the housing 101.

[0025] The clutch plates 103 are flat, annular parts pressed against the wet friction plates 200 described later, and are formed by punching out a thin plate material made of SPCC (cold rolled steel) into an annular shape. Oil grooves (not shown) having a depth of several μm to several tens of μm are formed on both side surfaces (front and back surfaces) of the clutch plates 103 for holding lubricating oil described later. Furthermore, both side surfaces (front and back surfaces) of the clutch plates 103 on which the oil grooves are formed are each subjected to a surface hardening treatment in order to improve wear resistance. Note that this surface hardening treatment is not directly related to the present invention, and therefore a description thereof will be omitted.

[0026] A friction plate holder 104 formed in a substantially cylindrical shape is disposed inside the housing 101 concentrically with the housing 101. A number of spline grooves are formed on the inner peripheral surface of the friction plate holder 104 along the axial direction of the friction plate holder 104, and a shaft 105 is splined into the spline grooves. Fitting The shaft 105 is a hollow shaft body, and one end (the right end in the figure) rotatably supports the input gear 102 and the housing 101 via a needle bearing 105a. FittingThe friction plate holder 104, which is connected to the shaft 105, is fixedly supported via a nut 105b. That is, the friction plate holder 104 rotates integrally with the shaft 105. Meanwhile, the other end (the left end in the figure) of the shaft 105 is connected to a transmission (not shown) of the two-wheeled vehicle.

[0027] A shaft-shaped push rod 106 is disposed penetrating the hollow portion of the shaft 105 while protruding from the one end (the right side in the figure) of the shaft 105. The push rod 106 is connected at the opposite end (the left side in the figure) to the end protruding from the one end (the right side in the figure) of the shaft 105 to a clutch operating lever (not shown) of the motorcycle, and slides within the hollow portion of the shaft 105 along the axial direction of the shaft 105 by operating the clutch operating lever.

[0028] A plurality of wet friction plates 200 (seven in this embodiment) are held on the outer peripheral surface of the friction plate holder 104 by spline engagement in a state in which the wet friction plates 200 are displaceable along the axial direction of the friction plate holder 104 and can rotate integrally with the friction plate holder 104, with the clutch plate 103 sandwiched between them.

[0029] Meanwhile, the inside of the friction plate holder 104 is filled with a predetermined amount of lubricating oil (not shown), and three cylindrical support columns 104a are formed therein (only one is shown in the figure). The lubricating oil is supplied between the wet friction plate 200 and the clutch plate 103 to absorb frictional heat generated between the wet friction plate 200 and the clutch plate 103 and to prevent wear of the friction material 210.

[0030] The three cylindrical support columns 104a are formed so as to protrude outward in the axial direction of the friction plate holder 104 (to the right in the figure), and a pressing cover 107 arranged at a position concentric with the friction plate holder 104 is attached to each of them via a bolt 108a, a receiving plate 108b, and a coil spring 108c. The pressing cover 107 is formed in a substantially circular plate shape with an outer diameter substantially the same as that of the wet friction plate 200, and is pressed toward the friction plate holder 104 by the coil spring 108c. A release bearing 107a is provided at the inner center of the pressing cover 107 at a position facing the right end of the push rod 106 in the figure.

[0031] (Configuration of Wet Friction Plate 200) As shown in detail in Fig. 2, the wet friction plate 200 is configured by providing an oil groove 203 and a friction material 210 on a flat annular core metal 201. The core metal 201 is a member that serves as the base of the wet friction plate 200, and is formed by punching out a thin plate material made of SPCC (cold rolled steel plate) into a substantially annular shape. In this case, the friction plate holder 104 and the spline Fitting An internal spline 202 is formed for this purpose.

[0032] On the side of this wet friction plate 200 facing the clutch plate 103, i.e., on the ring-shaped plate surface of the core metal 201 facing the clutch plate 103, a plurality of (32 in this embodiment) small pieces of friction material 210 are provided along the circumferential direction of the core metal 201 via oil grooves 203 consisting of gaps.

[0033] The oil groove 203 is a flow path for guiding lubricating oil between the inner and outer circumferential edges of the core metal 201 of the wet friction plate 200, and is also an oil retaining portion for keeping the lubricating oil between the wet friction plate 200 and the clutch plate 103, and is formed by a gap between the friction materials 210 adjacent to each other. In this embodiment, the oil groove 203 is formed by a portion formed in a fan shape between each of the four small piece-like friction materials 210, and a portion formed in a linear shape extending between each of the four friction materials 210 arranged between two fan-shaped oil grooves 203. The shape and number of the oil groove 203 are appropriately set according to the specifications of the wet friction plate 200.

[0034] Friction material 210, which improves frictional force against clutch plate 103, is made of small pieces of paper material attached in the circumferential direction of core metal 201. More specifically, friction material 210 is made by impregnating a paper body with a thermosetting resin and then curing it.

[0035] Here, the paper body is composed of an aggregate of at least one type of fiber selected from organic fibers and inorganic fibers, to which a filler is added. The organic fibers may be composed of one or more types of wood pulp, synthetic pulp, polyester fibers, polyamide fibers, polyimide fibers, polyvinyl alcohol modified fibers, polyvinyl chloride fibers, polypropylene fibers, polybenzimidazole fibers, acrylic fibers, carbon fibers, phenolic fibers, nylon fibers, and cellulose fibers. The inorganic fibers may be composed of one or more types of glass fibers, rock wool, potassium titanate fibers, ceramic fibers, silica fibers, silica-alumina fibers, kaolin fibers, bauxite fibers, kyanoid fibers, boron fibers, magnesia fibers, and metal fibers.

[0036] The filler acts as a friction modifier and / or a solid lubricant, and may be one or more of barium sulfate, calcium carbonate, magnesium carbonate, silicon carbide, boron carbide, titanium carbide, silicon nitride, boron nitride, alumina, silica, zirconia, cashew dust, rubber dust, diatomaceous earth, graphite, talc, kaolin, magnesium oxide, molybdenum disulfide, nitrile rubber, acrylonitrile-butadiene rubber, styrene butadiene rubber, silicone rubber, and fluororubber. Thermosetting resins include phenolic resins, melamine resins, epoxy resins, urea resins, and silicone resins.

[0037] The friction material 210 is formed to a thickness of 0.3 mm or more and 0.6 mm or less, and is attached to the core metal 201 via an adhesive (not shown). In this embodiment, the friction material 210 is configured by arranging eight small pieces in the circumferential direction of the core metal 201 via eight fan-shaped oil grooves 203, each of which is made up of four rectangular small pieces extending in the circumferential direction of the core metal 201 and three linear oil grooves 203. The shape and number of the friction material 210 are appropriately set according to the specifications of the wet friction plate 200, and are not limited to this embodiment.

[0038] Microgrooves 211 are formed on the surface of this friction material 210. The microgrooves 211 are portions for determining the retention and dischargeability of lubricating oil on the friction material 210, and are formed in the shape of grooves recessed in a concave shape on the surface of the friction material 210. More specifically, as shown in Fig. 3, the microgrooves 211 are formed in the shape of grooves that open on the surface of the friction material 210 and are recessed inward. In this case, a groove inner surface 212 forming the microgrooves 211 is composed of an uneven surface having irregular unevenness.

[0039] In this embodiment, the microgroove 211 is formed as an inclined surface in which two side surfaces 212a, 212b extend toward the inside of the friction material 210 so as to approach each other, and the cross-sectional shape is formed to be substantially V-shaped (triangular). In this embodiment, the microgroove 211 is formed to have a groove width of approximately 100 μm and a maximum depth of approximately 200 μm.

[0040] The fine grooves 211 are formed in an arc shape that extends continuously along the circumferential direction of the core metal 201 on the friction material 210. In this embodiment, the fine grooves 211 are formed of three arcs aligned in the radial direction of the wet friction plate 200. In this case, the three arcs are configured as concentric circles centered on the center of the core metal 201.

[0041] (Manufacture of wet friction plate 200) Next, a manufacturing method of the wet friction plate 200 thus configured will be described with reference to Fig. 4. First, in the first step, an operator manufactures the friction material 210 (friction material manufacturing step). Specifically, the manufacturing step of the friction material 210 mainly includes a papermaking step and a curing step.

[0042] The papermaking process is a process of filtering out fibers dispersed in a liquid to form a long sheet-like paper body, and is a conventionally known method. Specifically, the papermaking process is a process of filtering out the raw materials for the paper body, i.e., the organic fibers and / or inorganic fibers, filler, and flocculant, from a slurry-like raw material liquid obtained by adding these raw materials to water and stirring them, filtering these raw materials into a long sheet-like form, and then drying the raw material to obtain a long sheet-like paper body. In this case, the paper body is dried until the moisture content is 10% or less.

[0043] Next, the curing process is a task of impregnating the paper body with a thermosetting resin and curing it. Specifically, the worker sprays a thermosetting resin liquid (phenolic resin liquid) onto the paper body, or immerses the paper body in the thermosetting resin liquid to impregnate the paper body with the thermosetting resin liquid, and then heats the paper body with a heater or a heated roller to cure the thermosetting resin liquid. In this case, the worker cures the thermosetting resin liquid to a semi-cured state in which the thermosetting resin liquid has changed to a solid but has not yet completely cured. In this way, the worker can obtain the friction material 210 made of the paper body in which the thermosetting resin liquid is in a semi-cured state.

[0044] Next, as a second step, the worker forms the fine grooves 211 on the friction material 210 (fine groove forming step). In this case, the worker performs the forming process of the fine grooves 211 using a laser processing device 300. Here, the laser processing device 300 is a mechanical device for irradiating the friction material 210 with laser light L to form the fine grooves 211.

[0045] As shown in Fig. 5, the laser processing apparatus 300 mainly includes a laser oscillator (not shown), a laser adjustment optical system (not shown), a laser head 301, a work table 302, a work transport mechanism 303, and a control device (not shown). The laser oscillator is a mechanical device for emitting laser light L for forming a fine groove 211 on the friction material 210. In this embodiment, the laser oscillator is an oscillator that oscillates a pulsed laser light having a frequency of 300 kHz, an output of 60 W, and a short pulse width such as nanoseconds, picoseconds, or femtoseconds. The laser adjustment optical system is composed of optical components such as various optical elements such as lenses and mirrors that guide the laser light L emitted by the laser oscillator to the laser head 301 while performing various adjustments such as correction of the beam diameter, beam shape, and aberration.

[0046] The laser head 301 is an optical device that emits laser light L guided from a laser adjustment optical system toward the work table 302 and focuses the light on a wet friction plate. The laser head 301 is configured to be displaceable in three axial directions, the X-axis direction, the Y-axis direction, and the Z-axis direction, which are orthogonal to each other, with respect to the work table 302. The laser oscillator, the laser adjustment optical system, and the laser head 301 themselves are known mechanical devices.

[0047] The work table 302 is a platform that supports the friction material 210 from below at a position facing the laser head 301, and is configured by forming a metal material into a flat plate shape. The work transport mechanism 303 is a mechanical device for transporting the long friction material 210 from one side to the other in the longitudinal direction, and is mainly configured with a pair of drive rollers that sandwich the friction material 210.

[0048] The control device is configured by a microcomputer including a CPU, ROM, RAM, etc., and comprehensively controls the overall operation of the laser processing device 300. Specifically, the control device controls the operation of each of the laser oscillator, the laser adjustment optical system, the laser head 301, and the workpiece transport mechanism 303 in accordance with instructions from an operator to place the friction material 210 on the worktable 302, and displaces the laser head 301 while irradiating the friction material 210 positioned on the worktable 302 with laser light L to form the fine grooves 211.

[0049] In this second step, the worker pulls out the friction material 210 wound in a roll shape and has the end of the pulled out friction material 210 gripped by the work transport mechanism 303, and then instructs the control device of the laser processing device 300 to process the fine grooves 211. In response to this instruction, the control device controls the operation of the work transport mechanism 303 to intermittently transport the friction material 210, thereby intermittently positioning the friction material 210 on the work table 302. Next, the control device displaces the laser head 301 in the X-axis direction and the Y-axis direction while emitting the laser light L from the laser head 301 toward the friction material 210 positioned on the work table 302, thereby displacing the laser light L on the friction material 210 to form the fine grooves 211.

[0050] In this embodiment, as shown in FIG. 6, the laser processing device 300 forms three microgrooves 211 formed in each of the four friction materials 210 arranged between the two fan-shaped oil grooves 203, in a state in which each is continuously connected along the width direction of the friction material 210. In this case, as shown in FIG. 7, each microgroove 211 is formed to have a V-shaped (triangular) cross section. The side surfaces 212a and 212b constituting each microgroove 211 are formed to be substantially flat planes with few irregularities. Moreover, each of these microgrooves 211 is formed to a depth deeper than the depth of the microgroove 211 to be finally formed. In FIG. 6, the friction material 210 relative to the microgroove 211 is virtually shown by a two-dot chain line. In addition, in FIG. 5 and FIG. 6, the conveying direction of the long friction material 210 is shown by a dashed arrow.

[0051] Next, in the third step, the worker prepares the core bar 201 and places the friction material 210 on each of the two plate surfaces of the core bar 201 (friction material placing step). Here, the core bar 201 is formed into an annular shape having the spline 202 by a separate press process. This press process is a conventionally known method and therefore will not be described here.

[0052] The worker applies a liquid adhesive to the entire plate surface of the core metal 201 using a tool such as a brush or a roller, and then places the friction material 210 on the adhesive. Here, a liquid thermosetting resin is used as the adhesive. The worker may cut the band-like friction material 210 placed on the core metal 201 to form small pieces of the friction material 210, or may place the band-like friction material 210 that has been cut into small pieces in advance on the core metal 201. These methods of arranging the friction material 210 on the core metal 201 are known techniques.

[0053] The friction material 210 arranged on the core metal 201 is temporarily fixed on the core metal 201 by the adhesive force of the uncured adhesive. Therefore, the worker can arrange the friction material 210 on both sides by turning the core metal 201 over. Note that in this third step, the worker can also apply the adhesive only to the position where the friction material 210 is to be arranged, or only in an annular shape along the circumferential direction where the friction material 210 is to be arranged. The worker can also apply the adhesive to the friction material 210.

[0054] Next, as a fourth step, an operator performs a crushing process on the fine grooves 211 (crushing process). This crushing process also serves as a process for attaching the friction material 210 to the core metal 201, and is performed using a hot press processing device 400. Here, the hot press processing device 400 is a mechanical device for pressing the friction material 210 while heating it, thereby crushing the fine grooves 211 and fixing the friction material 210 to the core metal 201. This hot press processing device 400 is a known mechanical device, so a detailed description will be omitted, but a brief description of its configuration will be given.

[0055] As shown in Fig. 8, the hot press processing device 400 mainly comprises a lower pressure plate 401, an upper pressure plate 402, a movable support device 403, and a control device. The lower pressure plate 401 is a component on which the core metal 201 is placed and which cooperates with the upper pressure plate 402 to sandwich and heat and press the core metal 201, and is formed by forming a metal material into a plate shape. In this case, a heater (not shown) which heats by passing electricity is provided inside the lower pressure plate 401. The lower pressure plate 401 is fixed to the upper surface of a lower base 403a of the movable support device 403.

[0056] The upper pressure plate 402 is a part disposed above the lower pressure plate 401 in opposition to the lower pressure plate 401, and cooperates with the lower pressure plate 401 to sandwich the core metal 201 and heat and press it, and is formed by forming a metal material into a plate shape. A heater (not shown) that heats by passing electricity is provided inside the upper pressure plate 402. The upper pressure plate 402 is fixed to the lower surface of the upper base 403c of the movable support device 403.

[0057] Movable support device 403 is a mechanical device that supports upper pressure plate 402 so that it can move toward or away from lower pressure plate 401 (see the dashed arrow in the figure), and is configured with lower base 403a, support pillar 403b, and upper base 403c. Lower base 403a is a metal flat plate that fixedly supports lower pressure plate 401. Support pillar 403b is a component that supports upper base 403c while guiding it in the direction of moving upper pressure plate 402 toward or away from lower pressure plate 401, and is configured with a plurality of metal rods that stand up from the outer edge of lower base 403a.

[0058] The upper base 403c is a metal flat plate that supports the upper pressure plate 402. Through holes are formed in the outer edge of the upper base 403c at positions corresponding to the support columns 403b, and the support columns 403b are slidably fitted into each of these through holes. The upper base 403c is supported by a hydraulic drive device (not shown) that hydraulically raises and lowers the upper base 403c.

[0059] The control device is configured by a microcomputer including a CPU, ROM, RAM, etc., and comprehensively controls the overall operation of the hot press processing device 400. Specifically, the control device controls the operation of each heater of the lower press plate 401 and the upper press plate 402 and each hydraulic drive device in the movable support device 403 according to instructions from an operator, and presses the core metal 201 with the lower press plate 401 and the upper press plate 402 while heating it, thereby crushing the friction material 210 including the fine grooves 211.

[0060] In this fourth step, the worker places the core metal 201, to which the friction material 210 is temporarily fixed, on the lower pressure plate 401, and then instructs the control device of the hot press processing device 400 to perform hot pressing of the friction material 210. In response to this instruction, the control device controls the operation of the heaters of the lower pressure plate 401 and the upper pressure plate 402 to heat the lower pressure plate 401 and the upper pressure plate 402 to a predetermined temperature, and then controls the operation of the hydraulic drive device to lower the upper pressure plate 402 toward the lower pressure plate 401 to press the entire core metal 201 (see the dashed arrow in the figure).

[0061] As a result, the core metal 201 is heated and pressed while being sandwiched between the lower pressure plate 401 and the upper pressure plate 402. In this case, the temperature at which the friction material 210 is heated, the pressure at which it is pressed, and the time for which they are performed are appropriately set according to the specifications of the wet friction plate 200, but it is necessary that the pressure and time are such that the friction material 210 is compressed in the thickness direction and that the thermosetting resin is completely solidified. Here, "the thermosetting resin is completely solidified" means that the thermosetting resin is solidified to an extent that it can withstand the use of the wet friction plate 200.

[0062] As a result, the semi-cured thermosetting resin contained inside the friction material 210 and the thermosetting resin applied between the core metal 201 and the friction material 210 are solidified in the core metal 201. Therefore, the friction material 210 is solidified in a state compressed in the thickness direction and is fixed onto the core metal 201. In this case, the friction material 210 is fixed onto the core metal 201 in a state compressed to a thickness of 1 / 10 or more and 1 / 2 or less of the thickness before pressure is applied.

[0063] 3, the fine grooves 211 formed on the friction material 210 are crushed in the thickness direction of the friction material 210. Specifically, the depth of the fine grooves 211 is reduced, and the pointed shape of the bottom of the groove is deformed into a wide shape, causing unevenness on the side surfaces 212a, 212b, so that the cross-sectional shape is generally formed into a substantially V-shape crushed in the thickness direction of the friction material 210.

[0064] Then, the control device heats and presses the core metal 201 with the lower pressure plate 401 and the upper pressure plate 402 for a predetermined time, and then controls the operation of the hydraulic drive device to raise the upper pressure plate 402 and separate it from the lower pressure plate 401, and stops heating the heaters of the lower pressure plate 401 and the upper pressure plate 402 (see the dashed arrows in the figure). Therefore, the worker can remove the core metal 201 to which the friction material 210 is fixed, i.e., the wet friction plate 200, from above the lower pressure plate 401. Thereafter, the worker performs a friction characteristic adjustment process and an inspection process to complete the wet friction plate 200, but a description of these processes will be omitted as they are not directly related to the present invention.

[0065] (Operation of the wet friction plate 200) Next, the operation of the wet friction plate 200 configured as above will be described. As described above, this wet friction plate 200 is used by being assembled in the wet multi-plate clutch device 100. As described above, this wet multi-plate clutch device 100 is disposed between the engine and the transmission in a vehicle, and transmits and cuts off the driving force of the engine to the transmission by the operation of a clutch operating lever by the vehicle operator.

[0066] That is, when a vehicle operator (not shown) operates a clutch operating lever (not shown) to move the push rod 106 backward (displaced to the left in the figure), the tip of the push rod 106 does not press the release bearing 107a, and the pressing cover 107 presses the clutch plate 103 by the elastic force of the coil spring 108c. As a result, the clutch plate 103 and the wet friction plate 200 are displaced toward the receiving portion 104b formed in a flange shape on the outer circumferential surface of the friction plate holder 104, and are pressed against each other and frictionally connected. As a result, the driving force of the engine transmitted to the input gear 102 is transmitted to the transmission via the clutch plate 103, the wet friction plate 200, the friction plate holder 104, and the shaft 105.

[0067] On the other hand, when the vehicle operator operates a clutch operating lever (not shown) to move the push rod 106 forward (displaced to the right in the figure), the tip of the push rod 106 presses the release bearing 107a, and the pressing cover 107 is displaced to the right in the figure against the elastic force of the coil spring 108c, and the pressing cover 107 and the clutch plate 103 are separated from each other. As a result, the clutch plate 103 and the wet friction plate 200 are displaced toward the pressing cover 107, and the state in which they were pressed against each other and connected is released, and they are separated from each other. As a result, the driving force is no longer transmitted from the clutch plate 103 to the wet friction plate 200, and the transmission of the driving force of the engine transmitted to the input gear 102 to the transmission is interrupted.

[0068] In the clutch-ON state where the clutch plate 103 and the wet friction plate 200 are in frictional contact with each other, part of the lubricating oil present on the friction material 210 enters the fine grooves 211 formed in the surface layer of the friction material 210. In this case, since the surface area of ​​the groove inner surface 212 of the fine grooves 211 is increased due to the unevenness, the amount of the lubricating oil that permeates the internal structure of the friction material 210 is increased, and the cooling effect of the friction material 210 can be improved.

[0069] In addition, in the clutch OFF state in which the clutch plate 103 and the wet friction plate 200 are separated, the micro grooves 211 have improved retention of lubricating oil due to the unevenness formed on the groove inner surface 212, thereby improving the cooling effect of the friction material 210.

[0070] In addition, even when the clutch plate 103 and the wet friction plate 200 are repeatedly pressed against or separated from each other, the bottom of the fine grooves 211 is not sharp and is formed wide, thereby suppressing the occurrence or progression of tears or cracks in the fine grooves 211 and improving the durability of the friction material 210.

[0071] As can be understood from the above operation description, according to the above embodiment, in the manufacturing method of the wet friction plate 200, even when the fine grooves 211 are formed by laser processing, the fine grooves 211 are crushed to form the side surfaces 212a, 212b into rough surfaces with severe irregularities, so that the retention of lubricating oil in the fine grooves 211 can be improved.

[0072] Furthermore, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the object of the present invention. In each of the modifications shown below, the same components as those of the wet friction plate 200 in the above embodiment are denoted by the same reference numerals as those of the wet friction plate 200, and the description thereof will be omitted.

[0073] For example, in the above embodiment, the microgroove 211 is formed to have a substantially V-shaped (triangular) cross-sectional shape. However, the microgroove 211 can be formed into a shape other than the V-shape, such as a U-shape or a circular arc shape, or other shapes, since the groove inner surface 212 is formed into a distorted shape by the crushing process.

[0074] In the above embodiment, the microgroove 211 is formed with a groove width of about 100 μm and a maximum depth of about 200 μm. However, the width of the microgroove 211 may be formed to be 10 μm or more and 1000 μm or less. The depth of the microgroove 211 may be formed to be 10 μm or more and 1000 μm or less.

[0075] In the above embodiment, the microgroove 211 is formed in an arc shape that extends continuously along the circumferential direction of the core metal 201 on the friction material 210. However, the microgroove 211 may be formed to extend in the radial direction of the core metal 201 or in other directions. In this case, the microgroove 211 may be formed to extend continuously in a straight line or curved line in the circumferential direction, radial direction, or other directions of the core metal 201, or may be formed in an intermittent straight line or curved line.

[0076] In the above embodiment, the microgroove 211 is formed of three arcs arranged in the radial direction of the wet friction plate 200. In this case, the three arcs are configured as concentric circles centered on the center of the core metal 201. However, it is sufficient that at least one microgroove 211 is formed. In addition, when the microgroove 211 is configured of a plurality of arcs arranged in the radial direction of the wet friction plate 200, it is natural that the microgroove 211 may be configured of arcs having different radii.

[0077] In the above embodiment, in the process of forming the microgroove 211 in the second step, the microgroove 211 is formed to have a substantially V-shaped (triangular) cross-sectional shape. However, in the process of forming the microgroove 211 in the second step, the microgroove 211 may be formed to have a shape other than the V-shape, such as a U-shape, a rectangular shape, or a circular arc shape, or other shapes.

[0078] Furthermore, in the above embodiment, the step of forming the microgrooves 211 was performed on the friction material 210 before it was placed on the core metal 201. This allows the worker to easily form the microgrooves 211 with good accuracy compared to processing the microgrooves 211 on the friction material on the core metal. In this case, the worker can reliably prevent the microgrooves 211 from being erroneously formed on the core metal 201. However, it goes without saying that the step of forming the microgrooves 211 may also be performed on the friction material 210 placed on the core metal 201. This allows the worker to form the microgrooves 211 with good accuracy at a precise position on the core metal 201.

[0079] In the above embodiment, the step of squeezing the fine grooves 211 was performed on the friction material 210 arranged on the core metal 201. This allows the worker to also perform the step of attaching the friction material 210 to the core metal 201, reducing the number of steps and enabling the wet friction plate 200 to be manufactured efficiently. However, it goes without saying that the step of squeezing the fine grooves 211 may also be performed on the friction material 210 before it is arranged on the core metal 201. This allows the worker to squeeze and mold different types of friction materials 210 or different types of fine grooves 211 in separate steps.

[0080] In the above embodiment, the manufacturing process of the friction material 210 is carried out in the first step. However, in the manufacturing method of the wet friction plate according to the present invention, instead of manufacturing the friction material 210, the paper body or the friction material 210 can be procured from the market.

[0081] In the above embodiment, the thermosetting resin is cured in a semi-cured state in the manufacturing process of the friction material 210 in the first step. As a result, in the crushing process of the fine grooves 211 in the fourth step, the worker can suppress the springback of the pressed friction material 210 and crush the fine grooves 211 with high precision to manufacture the wet friction plate 200. In this case, the crushing process of the fine grooves 211 in the fourth step can be performed with a lower pressure for pressing the friction material 210 compared to the case where the friction material 210 in which the thermosetting resin is completely cured is pressed. However, the thermosetting resin can be completely cured in the manufacturing process of the friction material 210 in the first step. In this case, in the crushing process of the fine grooves 211 in the fourth step, the friction material 210 in which the thermosetting resin is completely cured is pressed to crush the fine grooves 211.

[0082] In the above embodiment, in the fourth step of crushing the fine grooves 211, the friction material 210 is pressed while being heated. However, the fourth step of crushing the fine grooves 211 may be performed by simply pressing the friction material 210 without applying heat to the friction material 210. In the manufacturing method of the wet friction plate 200, the friction material 210 on the core metal 201 may be heated to be bonded to the core metal 201, and then the friction material 210 is pressed to perform the crushing step of the fine grooves 211.

[0083] In the above embodiment, a thermosetting resin is used as the adhesive for fixing the friction material 210 onto the core metal 201. However, it goes without saying that an adhesive other than a thermosetting resin may be used as the adhesive for fixing the friction material 210 onto the core metal 201. For example, the adhesive may be an elastomer adhesive (such as a silicone or modified silicone adhesive), a thermoplastic resin adhesive (such as a polyvinyl alcohol, polyamide or polyolefin adhesive), or an inorganic adhesive (such as a ceramic adhesive or sodium silicate).

[0084] In the above embodiment, the laser processing apparatus 300 is configured so that the laser head 301 can be displaced in three axial directions, namely, the X-axis direction, the Y-axis direction, and the Z-axis direction, which are perpendicular to each other. However, the laser processing apparatus 300 can adopt other configurations as long as it is configured so that the fine grooves 211 can be formed in the friction material 210. Therefore, the laser processing apparatus 300 can be configured so that, for example, instead of or in addition to displacing the laser head 301 and / or the work table 302, a galvano scanner or a polygon mirror is provided in the laser head 301 to scan the laser light L in the X-axis direction and the Y-axis direction, respectively.

[0085] In the above embodiment, the friction material 210 is made of a paper body. However, the friction material 210 can be made of a material other than paper, such as a rubber material or a cork material.

[0086] In the above embodiment, an example has been described in which the wet friction plate according to the present invention is applied to the wet friction plate 200 used in the wet multi-plate clutch device 100. However, the wet friction plate according to the present invention may be any wet friction plate used in oil, and may be applied to the wet multi-plate clutch device 100 as well as wet friction plates used in brake devices that brake the rotational motion of a prime mover. [Explanation of symbols]

[0087] L: laser light, 100... Wet multi-plate clutch device, 101... Housing, 102... Input gear, 102a... Torque damper, 102b... Rivet, 103... Clutch plate, 104... Friction plate holder, 104a... Cylindrical support column, 104b... Receiving portion, 105... Shaft, 105a... Needle bearing, 105b... Nut, 106... Push rod, 107... Pressing cover, 107a... Release bearing, 108a... Bolt, 108b... Receiving plate, 108c... Coil spring, 200... wet friction plate, 201... core metal, 202... spline, 203... oil groove, 210...friction material, 211...fine groove, 212...groove inner surface, 212a, 212b...side surface, 300... laser processing device, 301... laser head, 302... work table, 303... work transport mechanism, 400... heat press processing device, 401... lower pressure plate, 402... upper pressure plate, 403... movable support device, 403a... lower base, 403b... support column, 403c... upper base.

Claims

1. A method for manufacturing a wet friction plate in which a friction material is provided along a circumferential direction on a surface of a flat annular core metal, the method comprising the steps of: a microgroove forming step of forming microgrooves in a concave shape on a surface of the friction material by irradiating the friction material with a laser beam while displacing the laser beam relative to the surface of the friction material; and a crushing step of pressing the friction material to crush and deform the fine grooves.

2. The method for producing a wet friction plate according to claim 1, further comprising the steps of: a friction material disposing step of disposing the friction material on the core metal, The fine groove forming step includes: A method for manufacturing a wet friction plate, comprising the steps of:

3. In the method for manufacturing a wet friction plate according to claim 2, The crushing step includes: A method for manufacturing a wet friction plate, comprising the steps of:

4. The method for producing a wet friction plate according to claim 1, further comprising the steps of: a friction material disposing step of disposing the friction material on the core metal, The fine groove forming step includes: The friction material is placed on the core metal, The crushing step includes: A method for manufacturing a wet friction plate, comprising the steps of:

5. The method for manufacturing a wet friction plate according to any one of claims 1 to 4, further comprising: The method includes a friction material manufacturing process for manufacturing a paper sheet in which a thermosetting resin is impregnated into an aggregate of countless fibers as the friction material, The crushing step includes: A method for manufacturing a wet friction plate, comprising pressing the friction material while applying heat thereto.

6. The method for manufacturing a wet friction plate according to claim 5, The friction material manufacturing process includes: The paper body is manufactured in a semi-cured state in which the thermosetting resin is cured to a degree that does not completely cure the thermosetting resin, The crushing step includes: a friction material that is in a semi-cured state and is then heated to completely cure the thermosetting resin;

7. In the method for manufacturing a wet friction plate according to claim 3 or 4, The friction material arrangement step includes: The friction material is disposed on the core metal via an adhesive, The crushing step includes: A method for manufacturing a wet friction plate, comprising the steps of pressing the friction material onto the core metal to attach the friction material to the core metal.

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