JP2012193282A - Method for manufacturing friction member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a friction member that can prevent the friction coefficient of a friction surface from decreasing while the dimension thereof is stabilized.SOLUTION: The method for manufacturing a friction member having a friction surface made of a thermoplastic resin containing fiber includes: a molding step S12 of molding a molded article from the fiber and the thermoplastic resin; a grinding step S13 of grinding the molded article into a shape of a friction member; and a leveling step S14 of leveling the friction surface by pressing the friction surface of the ground friction member with a pressing member heated to or above the softening point of the thermoplastic resin to soften the thermoplastic resin on the surface layer of the friction member.

Description

  The present invention relates to a method for manufacturing a friction member including a friction surface made of a thermoplastic resin containing fibers, and relates to a method for manufacturing a friction member that requires dimensional accuracy in the friction member.

  Conventionally, friction members (sliding members) have been used in various devices such as engines, transmissions, and clutches in automobiles. By improving the braking characteristics (for example, torque transmission characteristics) of these friction members, the operation of the devices is improved. Various developments have been made to prevent defects and improve reliability.

  For example, FIGS. 6A and 6B show a conventional clutch 90, and a release lever 91 of the clutch is connected to a clutch pedal 93 via a release fork 92. The release lever 91 is connected to a push rod 91b of a cylinder 91a that is rotatably supported by the clutch housing 97 in a penetrating manner, an arm 91c connected to the push rod 91b at one end, and the other end of the push rod 91b. A clutch release lever yoke 91d that is urged by a coil spring 95 and engages with a clutch release bearing hub 94 is provided. Further, the clutch release bearing hub 94 is pressed by the operation of the clutch pedal 93.

  On the other hand, on the drive side of the clutch, a clutch disk 82 that contacts and separates from the flywheel 81 is bonded to the clutch plate 83, and a pressure plate 84 is disposed so as to face this. And the cover 86 is provided so that the clutch shaft 87 which covers these members may be penetrated (refer patent document 1).

  Here, the friction members (mechanical parts) having friction surfaces such as the thrust washer of the clutch disk 82, the clutch release bearing hub 94, and the push rod 91b of the cylinder require dimensional accuracy in order to stabilize torque transmission. Therefore, conventionally, a metal material, a metal material or the like is generally manufactured by machining such as cutting or turning.

Japanese Utility Model Publication No. 63-69828

  Incidentally, in recent years, resin materials containing fibers have attracted attention in order to reduce the weight and increase the friction of friction members such as the above-described mechanical parts. When the above-described friction member is manufactured by machining using a resin containing such fibers, the friction surface, which is a machining surface, becomes rough due to the fibers, and the fibers exposed to the friction surface cause friction members. The coefficient of friction will be low.

  Therefore, for example, when a friction member is molded by melting a resin containing fibers and injecting the resin into a mold, the friction surface is small, and the friction coefficient is reduced due to the exposed fibers. Can be suppressed. However, when the friction member is formed by molding, there is a possibility that the dimensional accuracy of the friction member may be reduced due to resin sink (heat shrinkage) compared to machining.

  The present invention has been made in view of such a problem, and the object of the present invention is to provide a friction member manufacturing method capable of suppressing a decrease in the friction coefficient of a friction surface while ensuring dimensional stability. Is to provide.

  The method for producing a friction member according to the present invention is a method for producing a friction member including a friction surface made of a thermoplastic resin containing fibers, and a step of forming a molded body from the fibers and the thermoplastic resin, The step of cutting the molded body into the shape of a friction member, and pressing the friction surface of the scraped friction member with a pressing member heated above the softening point of the thermoplastic resin, including the friction surface And softening the thermoplastic resin on the surface layer of the friction member to smooth the friction surface.

  According to the present invention, first, a molded body is formed by melting a thermoplastic resin containing fibers. Next, the molded body is cut into the shape of the friction member. Thus, by cutting into the shape of the friction member, the dimensional accuracy of the friction member can be increased as compared with the case of forming the friction member. At this time, since the surface of the molded body corresponding to the friction surface is also shaved, fluffy fibers are exposed on the surface of the obtained friction member.

  Therefore, the pressing member is heated to a temperature equal to or higher than the softening point of the thermoplastic resin, and the friction surface is pressed with the pressing member. Thereby, the thermoplastic resin of the surface layer of the friction member including the friction surface is softened, and the friction surface is smoothed. That is, in this process, the fiber exposed to the surface of the friction is made to adhere to or enter the softened thermoplastic resin of the surface layer by cutting into the shape of the friction member, thereby smoothing the friction surface. Is done. As a result, it is possible to suppress a decrease in the friction coefficient of the friction member due to the fibers exposed on the friction surface.

  Here, the “fiber” in the present invention is a fiber for reinforcing a thermoplastic resin and ensuring a friction coefficient, and may be either a short fiber or a long fiber. In addition, the material of the fiber is not particularly limited as long as the function described above can be exhibited. Examples thereof include glass fibers, carbon fibers, aramid fibers, alumina fibers, boron fibers, steel fibers, PBO fibers, organic fibers, and high-strength polyethylene fibers.

  The “thermoplastic resin” as used in the present invention refers to a resin (matrix resin) for connecting fibers together. The material of the thermoplastic resin is not particularly limited as long as the fibers can be connected to each other without damaging the fibers described above during softening. For example, a crystalline thermoplastic resin or an amorphous thermoplastic resin can be used, for example, an olefin resin such as nylon resin, polycarbonate resin, polyamide resin, polypropylene resin, acrylic resin, or ABS resin. A thermoplastic resin having a higher melting point (higher softening point) than these may be used.

  In addition, the friction member as used in the field of this invention is a member which has a friction surface in the surface which carries out frictional contact with the other party material, and restrict | limits (brakes) relative movement with the other party material by this friction surface. . Therefore, the friction surface is a surface in frictional contact with the counterpart material. The term “smooth” as used in the present invention refers to smoothing a friction surface (a friction surface including fibers exposed to the friction surface) in the cutting process.

  Furthermore, as a preferred aspect, a step of smoothing the friction surface is performed so that the fibers of the friction surface enter the thermoplastic resin of the surface layer. That is, in this aspect, the friction surface is smoothed so that all the fibers on the friction surface are embedded in the surface thermoplastic resin and the friction surface is covered with the thermoplastic resin.

  According to this aspect, since the fiber on the friction surface is coated with the thermoplastic resin, only the fiber is hardly exposed on the friction surface when the friction member is used. Thereby, even if it is a case where it uses for a long time, the fall of the friction coefficient of a friction member can be suppressed. Such smoothing can be achieved by adjusting the heating temperature, heating time, and pressing force of the pressing member.

  According to the present invention, even when fibers are impregnated with a thermoplastic resin, it is possible to suppress a decrease in the friction coefficient of the friction surface while ensuring dimensional stability.

The flowchart for demonstrating each process of the manufacturing method of the friction member which concerns on this embodiment. It is a schematic diagram for demonstrating each process shown in FIG. 1, (a) is sectional drawing for demonstrating a kneading | mixing process, (b) is sectional drawing for demonstrating a formation process, (c) is The perspective view for demonstrating a cutting process, (d) is a perspective view for demonstrating a smoothing process. It is typical sectional drawing of the friction surface of the friction member before and behind a smoothing process, (a) is sectional drawing of the friction surface before a smoothing process, (b) is sectional drawing of the friction member after a smoothing process. The figure which showed the relationship between the dimensional accuracy of the friction member which concerns on Example 1, and Comparative Examples 1 and 2, and surface roughness. The figure which showed the relationship between the friction coefficient of the friction member which concerns on Example 1, and Comparative Examples 1 and 2 and surface roughness. It is a figure for demonstrating the conventional clutch, (a) is a whole perspective view, (b) is sectional drawing of (a).

  Embodiments of the following method for manufacturing a friction member according to the present invention will be described.

  FIG. 1 is a flowchart for explaining each step of the friction member manufacturing method according to the present embodiment. FIG. 2 is a schematic diagram for explaining each step shown in FIG. 1, (a) is a sectional view for explaining a kneading step, (b) is a sectional view for explaining a molding step, (C) is a perspective view for demonstrating a grinding process, (d) is a perspective view for demonstrating a smoothing process.

  FIG. 3 is a schematic cross-sectional view of the friction surface of the friction member before and after the smoothing step, (a) is a cross-sectional view of the friction surface before the smoothing step, and (b) is a friction member after the smoothing step. FIG.

  First, as shown in FIG.1 and FIG.2 (a), kneading | mixing process S11 is performed. The fibers 2 and the thermoplastic resin 3 (pellets) are charged into the charging port 21 of the twin screw extruder 20. The twin-screw extruder 20 is heated until the thermoplastic resin 3 is melted, the molten thermoplastic resin 3 and the fibers 2 are uniformly kneaded, and the bulk material that becomes the kneaded product is extruded from the twin-screw extruder 20. Here, a twin-screw extruder was used to knead the fiber and the thermoplastic resin. However, as long as the fiber 2 and the thermoplastic resin 3 can be uniformly mixed together, it is particularly limited to this apparatus. It is not something.

  Here, the fiber 2 may be, for example, any of inorganic fiber, organic fiber, and metal fiber, and more preferably glass fiber, carbon fiber, aramid fiber, alumina fiber, boron fiber, steel fiber, PBO. Examples thereof include fibers, and fibers such as high-strength polyethylene fibers. Examples of the thermoplastic resin 3 include nylon resins, polycarbonate resins, polyamide resins, polypropylene resins and other olefin resins, acrylic resins, and ABS resins.

  Next, as shown in FIG.1 and FIG.2 (b), shaping | molding process S12 is performed. The obtained bulk material 4 is put into the cylinder 31 of the injection molding device 30, heated until the bulk material 4 is softened, and pushed out by the plunger 32. A molding die 40 composed of upper and lower molds is connected to the tip of the injection molding apparatus 30 in the injection direction. Thereby, the bulk material 4 pushed out by the plunger 32 is molded into a molded body in the molding die 40.

  The obtained molded body has such a size and shape that the friction member 7 can be machined from the molded body by machining, and such a size and shape are contained in the molding die 40. A cavity 41 is formed so that the molded body 5 can be molded. Here, although it shape | molded using the injection molding apparatus 30, you may manufacture a molded object by connecting a shaping | molding die to the biaxial extruder 20 mentioned above.

  Then, as shown in FIG.1 and FIG.2 (c), the cutting process S13 is performed. Here, the molded body 5 is cut into the shape (specifically, ring shape) of the friction member 7 described later by mechanical processing (specifically, cutting and turning). In FIG. 1C, cutting is performed using a cutting tool 34. In this manner, by cutting into the shape of the friction member 7, the dimensional accuracy of the friction member 7 can be increased as compared with the case of forming the friction member. The cutting method of the molded body 5 is not particularly limited as long as it can be cut into a desired shape.

  Next, as shown in FIG.1 and FIG.2 (d), smoothing process S14 is performed. Here, the scraped friction surface 7a of the friction member 7 is pressed by a disk-shaped pressing member 50 having a pressing surface 51 corresponding to the shape of the friction surface 7a. Specifically, the friction including the friction surface 7 a is achieved by heating the pressing member 50 to a temperature equal to or higher than the softening point of the thermoplastic resin 3 constituting the friction member 7 and pressing the friction surface 7 a with the heated pressing member 50. The thermoplastic resin 3 on the surface layer of the member 7 is softened to smooth the friction surface 7a.

  As a result, as shown in FIG. 3A, the friction surface 7a of the friction member 7 after the cutting process is a cutting surface, so that a part of the fiber 2 is exposed from the friction surface 7a so as to become fluffy. However, as shown in FIG. 3 (b), by pressing with the pressing member 50, the partially exposed fiber 2 is brought into close contact with the softened thermoplastic resin 3 on the surface layer, or enters the inside thereof, whereby the friction surface 7a can be smoothed. As a result, the obtained friction member 7 can suppress a decrease in the friction coefficient of the friction member 7 due to the fibers 2 exposed to the friction surface 7a. Further, since only the surface layer of the friction member is softened, the dimensional accuracy can be substantially maintained.

  Here, in the smoothing step, for example, when the member that is in frictional contact with the friction member 7 on the friction surface is a metal material such as iron, the fibers 2 are not exposed to the friction surface 7a (that is, the fibers 2 are frictionally exposed). It is more preferable to perform a smoothing treatment (so as to sink into the thermoplastic resin 3 on the surface layer of the member).

  For example, when glass fiber is contained in a nylon resin, which is a thermoplastic resin, the content of fibers having a fiber length of 10 to 30 mm and a fiber diameter of 10 to 50 μm is set to 10 to 40% by mass, and the pressing member 50 is heated to 100 ° C. or higher. When the pressing pressure is set to 1 to 10 MPa and the pressing time is set to 10 seconds to 1 minute, the fibers 2 are not exposed to the friction surface 7a, and the fibers 2 of the friction surface 7a enter the nylon resin of the surface layer, and the friction Only the nylon resin is exposed on the surface 7a.

  Here, the pressing surface 51 of the pressing member 50 that contacts the friction surface 7a is planar. However, when the friction surface is a curved surface, the pressing surface (curved surface) corresponding to the curved surface is a pressing surface. A member may be used.

  For example, as shown in FIGS. 6A and 6B described above, such a friction member requires dimensional accuracy such as a thrust washer for the clutch disk 82, a clutch release bearing hub 94, and a push rod 91b for the cylinder. And it can use suitably for the member by which a high friction surface is requested | required compared with others.

Hereinafter, the present invention will be described by way of examples.
(Example)
<Production of friction member>
First, as a starting material, a nylon resin was prepared as a thermoplastic resin, and glass fibers (bundles) having a diameter of 20 μm and a fiber length of 15 mm were prepared as fibers. Next, these were kneaded so that the glass fibers were uniformly dispersed in the nylon resin so that the mass of the glass fibers was 30% by weight based on the total mass, and then a molded body was prepared. Further, the molded body was cut to produce a friction member (disk test) of 30 mm × 30 mm × 5 mm.

  Next, a pressed member heated to 150 ° C., which is higher than the softening point temperature (thermal deformation start temperature) of the nylon resin, is pressed on the scraped friction surface (friction surface) under the condition that the pressing time is 2 MPa and the pressing time is 1 minute. did. Thereby, the thermoplastic resin of the surface layer of the friction member including the friction surface was softened, and the friction surface was made smooth. Under these conditions, the fibers on the friction surface were coated with a thermoplastic resin.

(Comparative Example 1)
A friction member was produced in the same manner as in Example 1. The difference from the embodiment is that the molded body is only cut and the friction surface is not smoothed by using the pressing member.

(Comparative Example 2)
A friction member was produced in the same manner as in Example 1. The difference from the first embodiment is that a friction member is manufactured by a molding die (the cutting process and the smoothing process are not performed).

<Measurement of surface roughness>
The surface roughness of the friction surface of the friction member according to Example and Comparative Examples 1 and 2 was measured with a contact-type surface roughness meter. The results are shown in FIGS.

<Measurement of dimensional change>
The dimensional accuracy of Example 1 and Comparative Examples 1 and 2 was measured. The result is shown in FIG. The dimensional accuracy referred to here is the difference between the dimension of the friction member having a thickness of 5 mm and the target value.

<Friction coefficient measurement test>
The ring-on-disk test was conducted according to the following procedure. First, a ring test piece made of a hot-rolled steel sheet (SHP28) having an outer diameter of 25.6 mm, an inner diameter of 20 mm, a height of 16 mm, and a center line average roughness Ra of 1 μm was manufactured as a counterpart material for the friction member described above.

  Next, the friction surface of 30 mm × 30 mm of the friction member (disk test piece) of Examples and Comparative Examples 1 and 2 and the cylindrical end surface of the ring test piece are brought into contact with each other, and are lubricated, with a peripheral speed of 100 mm / second, surface. The change with time of the friction coefficient was measured under a pressure of 1 MPa and room temperature. The result is shown in FIG.

<Result>
(1) As shown in FIG. 4, the friction member according to the example had better dimensional accuracy than that of Comparative Example 2.
(2) As shown in FIGS. 4 and 5, the surface roughness according to the example was comparable to that of Comparative Example 2 and was smaller than that of Comparative Example 1. In addition, the friction surface of the Example and Comparative Example 2 had no fibers, and the friction surface of Comparative Example 1 had fiber fluff.
(3) As shown in FIG. 5, the friction coefficient according to Example 1 was higher than that of Comparative Example 1 and was comparable to that of Comparative Example 2.

<Discussion>
The result (1) came to be because the friction member according to the example was manufactured by machining by machining, and in the case of Comparative Example 2, the dimensional accuracy was increased by the thermal contraction of the resin in the mold. It is thought that it was not stable.

  It is considered that the result (2) came to show that the fuzzy fibers were not exposed on the friction surfaces of Example and Comparative Example 2.

  As shown in the result (3), the reason why the friction coefficient of the example and the comparative example 2 is higher than that of the comparative example 1 is considered that the decrease of the friction coefficient caused by the fluffy fibers did not occur.

  As mentioned above, although it explained in full detail using embodiment of this invention, a concrete structure is not limited to this embodiment and an Example, There exists a design change in the range which does not deviate from the summary of this invention. They are also included in the present invention.

  3: Thermoplastic resin, 2: Fiber, 4: Bulk material, 5: Molded body, 7: Friction member, 7a: Friction surface, 7b: Surface layer, 20: Twin screw extruder, 21 inlet, 30: Injection molding device 32: Plunger, 34: Bite, 40: Mold, 41: Cavity, 50: Pressing member, 51: Pressing surface, S11: Kneading step, S12: Molding step, S13: Grinding step, S14: Smoothing step

Claims (2)

A method of manufacturing a friction member including a friction surface made of a thermoplastic resin containing fibers,
Forming a molded body from the fibers and the thermoplastic resin;
Cutting the molded body into the shape of a friction member;
By pressing the friction surface of the scraped friction member with a pressing member heated above the softening point of the thermoplastic resin, the thermoplastic resin on the surface of the friction member including the friction surface is softened, And a step of smoothing the friction surface.   The method for producing a friction member according to claim 1, wherein the step of smoothing the friction surface is performed so that the fibers of the friction surface enter the thermoplastic resin of the surface layer.

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