Manufacturing method of molding material for plastic gears, and manufacturing method of plastic gears

Abstract

To provide a method for manufacturing a molding material for a resin gear, that can strengthen the resin gear and is easy to handle, and a method for manufacturing the resin gear.SOLUTION: A method for manufacturing a molding material 6 for a resin gear comprises: a first step for preparing a raw material 5 containing a thermocurable resin powder 2 and a wet fiber 3; and a second step for forming the molding material 6 for the resin gear by mixing the raw material 5 by a mixer 10 for a predetermined time. The wet fiber 3 contains a first fiber 3P being a para-aramid fiber, and a second fiber 3M being a meta-aramid fiber. A fiber length of the first fiber 3P is 3±1 mm. A fiber length of the second fiber 3M is longer than the fiber length of the first fiber 3P.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for producing a molding material for a resin gear, and a method for producing a resin gear. [Background technology]

[0002] Resin gears are lightweight and quiet, and are widely used, for example, as gears for vehicles or industrial use. A method using a molding material for resin gears containing fibers and a thermosetting resin is known as a manufacturing method for such resin gears. For example, the manufacturing method described in Patent Document 1 includes a step of dispersing phenolic resin powder and aramid fibers in water and forming the material into a sheet, and a step of cutting the obtained molding material into a gear shape and compressing the resulting base body obtained by stacking a plurality of the sheets while heating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-51097 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, in the above-mentioned technology, there are cases where high bending strength is desired for the resin gear, and in such cases, a molding material capable of increasing the strength of the resin gear is required. In addition, in the above-mentioned technology, it is desirable that the molding material be easy to handle when manufacturing the resin gear.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a method for producing a molding material for plastic gears which enables the production of plastic gears with high strength and which is easy to handle, and a method for producing plastic gears. [Means for solving the problem]

[0006] A method for producing a molding material for a resin gear according to one embodiment of the present invention is a method for producing a molding material for a resin gear, the method comprising: a first step of preparing raw materials including a thermosetting resin powder, wet fibers or fibers realizing the wet fibers, and water; and a second step of mixing the raw materials for a predetermined time using a mixer to form the molding material for a resin gear, the wet fibers or fibers including first fibers that are para-aramid fibers and second fibers that are meta-aramid fibers, the fiber length of the first fibers being 3 mm±1 mm, and the fiber length of the second fibers being longer than the fiber length of the first fibers.

[0007] In this method for producing a resin gear molding material, the raw materials are mixed for a predetermined time by a mixer, and resin powder is attached to the surface of wet fibers or fibers including the first fibers, which are para-aramid fibers, and the second fibers, which are meta-aramid fibers, to form a resin gear molding material. Here, by using the first fibers having a fiber length of 3 mm ± 1 mm, the formed resin gear molding material is prevented from becoming small powder or large lumps, and it is possible to easily handle the resin gear molding material when manufacturing a resin gear. Furthermore, by using the second fibers having a fiber length longer than the fiber length of the first fibers, which is 3 mm ± 1 mm, it is found that, for example, the fiber orientation of the manufactured resin gear is easily extended in the direction perpendicular to the load direction that causes bending, and the bending strength is improved. Therefore, according to the present invention, it is possible to obtain a resin gear molding material that can increase the strength of the resin gear and is easy to handle.

[0008] In the method for producing a resin gear molding material according to one aspect of the present invention, the fiber length of the second fibers may be at least twice as long as the fiber length of the first fibers, thereby further improving the bending strength of the produced resin gear.

[0009] In the method for producing a resin gear molding material according to one aspect of the present invention, the fiber length of the second fibers may be 6 mm±1 mm. In this case, the bending strength of the produced resin gear can be further improved, and at least a portion of the formed resin gear molding material can be granulated to an appropriate size, making the resin gear molding material easier to handle.

[0010] In the method for producing a resin gear molding material according to one aspect of the present invention, the mixer may have a container for storing the raw materials and a stirring blade disposed in the container for stirring the raw materials. By using such a mixer, it becomes possible to efficiently mix the raw materials.

[0011] In the method for producing a resin gear molding material according to one aspect of the present invention, the fiber volume fraction of the raw material may be 40 volume % or more, which can further improve the bending strength of the produced resin gear.

[0012] In the method for producing a resin gear molding material according to one aspect of the present invention, the ratio of the second fibers in the wet fibers or fibers may be 50% by weight or more, which effectively achieves the above-mentioned effect of obtaining a resin gear molding material that is easy to handle and can increase the strength of the resin gear.

[0013] A method for manufacturing a plastic gear according to one embodiment of the present invention is a method for manufacturing a plastic gear including an annular resin part and a metal bushing using a plastic gear molding material manufactured by the above-mentioned method for manufacturing a plastic gear molding material, and includes the steps of filling a mold with the plastic gear molding material and pressurizing it to form a first annular intermediate, placing the first intermediate and the metal bushing in the mold and heating and compressing them to form a second annular intermediate, and forming a tooth profile on the outer periphery of the second intermediate.

[0014] In this method for producing a plastic gear, the molding material resin member produced by the above-mentioned method for producing a plastic gear molding material is used for molding, which makes it possible to increase the strength of the plastic gear and to facilitate handling of the plastic gear molding material when producing the plastic gear. Effect of the Invention

[0015] According to the present invention, it is possible to provide a method for producing a molding material for a resin gear, which is capable of suppressing the occurrence of poor resin impregnation in a molded product, a method for producing a resin gear, and a molding material for a resin gear. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a front view showing a resin gear according to an embodiment. [Diagram 2] Fig. 2(a) is a diagram for explaining a method for producing a resin gear molding material according to an embodiment, and Fig. 2(b) is a diagram continuing from Fig. 2(a). [Diagram 3] Fig. 3(a) is a photograph showing a resin gear molding material according to an embodiment, and Fig. 3(b) is a photograph showing an enlarged portion of Fig. 3(a). [Figure 4] FIG. 4 is a schematic perspective view showing a mold used for molding a preform according to the embodiment. [Diagram 5] FIG. 5 is a perspective view showing a preform according to the embodiment. [Figure 6] Fig. 6(a) is a schematic cross-sectional view showing a mold for heat compression molding, and Fig. 6(b) is a cross-sectional view showing a molded product as a second intermediate body. [Figure 7] Fig. 7(a) is a photograph illustrating the fiber orientation of a resin gear manufactured using a conventional molding material, and Fig. 7(b) is a photograph illustrating the fiber orientation of a resin gear manufactured using the resin gear molding material according to the embodiment. [Figure 8] Fig. 8(a) is a schematic diagram illustrating the fiber orientation of a resin gear manufactured using a conventional molding material, and Fig. 8(b) is a schematic diagram illustrating the fiber orientation of a resin gear manufactured using the resin gear molding material according to the embodiment. [Figure 9] FIG. 9 is a schematic perspective view showing a mold used for molding the test piece. [Figure 10]Fig. 10(a) is a graph showing the evaluation results of the bending strength of the test pieces, and Fig. 10(b) is a graph showing other evaluation results of the bending strength of the test pieces. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0018] As shown in Fig. 1, a resin gear 1 manufactured by the manufacturing method according to this embodiment is a so-called high-strength resin gear, and is used as a gear for vehicles or industrial use. For example, the resin gear 1 can be used as a balance shaft gear or a camshaft gear in an engine. The resin gear 1 includes a metal bush 8 and a resin member 9. The resin gear 1 is a spur gear.

[0019] The metal bush 8 is a member attached to, for example, a rotating shaft (not shown). The metal bush 8 is annular. The metal bush 8 is made of a metal such as stainless steel. A through hole 8h is provided in the metal bush 8. A rotating shaft is inserted into the through hole 8h. A plurality of protrusions 8a are provided on the outer circumferential surface of the metal bush 8. The protrusions 8a are formed at predetermined intervals in the circumferential direction. The protrusions 8a are embedded in a resin member 9. The resin member 9 is a member that meshes with another gear. The resin member 9 is annular. The resin member 9 is made of resin. The resin member 9 is provided around the metal bush 8. A tooth profile 9a is formed on the outer circumferential portion of the resin member 9. A plurality of tooth profiles 9a are formed at predetermined intervals in the circumferential direction. Note that, instead of the plurality of protrusions 8a in the circumferential direction, one annular protrusion may be provided.

[0020] Next, an example of a manufacturing method according to this embodiment will be described.

[0021] The manufacturing method according to this embodiment includes a manufacturing method for manufacturing a resin gear molding material, which is a molding material for a resin gear 1, and a manufacturing method for manufacturing a resin gear 1 using the resin gear molding material.

[0022] [Manufacturing molding materials for plastic gears] First, a molding material for a resin gear is manufactured. As shown in Fig. 2(a), a raw material 5 containing (i) a thermosetting resin powder 2, (ii) a wet fiber 3 having a moisture content of 10 to 25% by weight, and (iii) an additive (or a filler) 4 is prepared (first step).

[0023] Examples of the resin powder 2 include phenol resin, imide resin, melamine resin, and epoxy resin. The resin powder 2 preferably has a particle size of about 1 to 200 μm. One type of resin or a combination of two or more types of resins can be used as the resin powder 2. The amount of the resin powder 2 in the raw material 5 is preferably 30 to 80% by weight, and more preferably 45 to 65% by weight.

[0024] The wet fiber 3 includes, as fibrous materials, first fibers 3P which are para-aramid fibers and second fibers 3M which are meta-aramid fibers. The fiber length of the first fibers 3P is 3 mm±1 mm. The fiber length of the second fibers 3M is longer than the fiber length of the first fibers 3P. The fiber length of the second fibers 3M is at least twice the fiber length of the first fibers 3P. The fiber length of the second fibers 3M is 6 mm±1 mm. The wet fiber 3 may include other fibrous materials. For example, the wet fiber 3 may include acrylic fibers, cellulose fibers, carbon fibers, phenolic resin fibers, polyimide fibers, inorganic fibers, etc. Examples of inorganic fibers include carbon fibers, alumina fibers, alumina-silica fibers, glass fibers, mineral fibers, and ceramic fibers.

[0025] The fiber volume ratio (fiber volume content) of the raw material 5 is preferably 40 volume % or more, and preferably 40 to 60 volume %. The fiber volume ratio is the volume ratio of the fibrous material contained in the raw material 5. The ratio of the first fibers 3P in the wet fibers 3 is preferably less than 50 weight %, and preferably 45 weight %. The ratio of the second fibers 3M in the wet fibers 3 is preferably 50 weight % to 100 weight %. The weight of the wet fibers 3 in the raw material 5 is preferably 25 to 55 weight %, and more preferably 35 to 45 weight %.

[0026] Examples of additive 4 include montanic acid ester, zinc stearate, talc, silicone rubber, zirconia, alumina, silica, barium sulfate, calcium carbonate, mica, potassium titanate, graphite, antimony trioxide, antimony disulfide, etc. The amount of additive 4 in raw material 5 is preferably 0 to 20% by weight, and more preferably 0.5 to 15% by weight.

[0027] As shown in FIG. 2(b), the raw material 5 is mixed for a predetermined time by a mixer 10. This forms the resin gear molding material 6 shown in FIG. 3(a) and FIG. 3(b) (second step). The resin gear molding material 6 contains a plurality of fine granules (fiber balls) as a part of it. The resin gear molding material 6 does not have a two-dimensional planar shape, but has a three-dimensional solid shape. The mixer 10 and its mixing method are not particularly limited as long as the raw materials can be mixed uniformly. For example, a Lödige mixer (manufactured by Lödige) and an Einrich mixer (manufactured by Nippon Eirich) can be used as the mixer 10.

[0028] In this embodiment, as shown in FIG. 2(b), an Einrich mixer is used as the mixer 10. The mixer 10 has a base 11, a mixing pan 12, a rotor 13, and a blade 14. The base 11 rotatably supports the mixing pan 12 and the rotor 13. The mixing pan 12 is a container that contains the raw material 5. The rotor 13 is a stirring blade that stirs the raw material 5. The rotor 13 is disposed in the mixing pan 12. In this mixer 10, the rotor 13 rotates at high speed, and the mixing pan 12 rotates, so that there is little dead zone in the mixing pan 12. In addition, in this mixer 10, the blade 14 scrapes off the material that is biased to the side of the mixing pan 12 due to centrifugal force, and further, since the mixing pan 12 is inclined, the scraped off material is brought into contact with the rotor 13, so that efficient mixing is performed.

[0029] [Manufacturing of plastic gears] Next, the resin gear 1 is manufactured using the formed resin gear molding material 6. (Formation of preform) First, the resin gear molding material 6 is preformed to form a preform as a first intermediate. Specifically, as shown in Fig. 4, a mold 20 including a lower mold 20B and an upper mold 20T is prepared, and the mold 20 is preheated to, for example, 80°C. The lower mold 20B has a cylindrical cavity 21. The upper mold 20T has a cylindrical protrusion 22 that fits into the cavity 21.

[0030] A required amount of the resin gear molding material 6 is measured and uniformly filled into the cavity 21 of the lower die 20B. After filling, the resin gear molding material 6 is pressed by applying force to the upper die 20T, for example, using a press machine. The pressing conditions are, for example, such that the filled resin gear molding material 6 is pressed at a pressure of 70 MPa for 10 seconds. As a result, as shown in FIG. 5, a preform 25 is formed by preforming the resin gear molding material 6. Thereafter, the preform 25 is removed from the die 20. The preform 25 is, for example, an annular object having an outer diameter of 90 mm and an inner diameter of 60 mm. The above-mentioned filling and pressing of the resin gear molding material 6 are repeated to form two preforms 25.

[0031] (Heat compression molding) A tooth forming die 30 shown in FIG. 6(a) is prepared, and the tooth forming die 30 is heated to 200±5°C. The two preforms 25 are dried in a dryer. The metal bush 8 is preheated to 90°C in a dryer. The dried preform 25 and the metal bush 8 are molded into the heated tooth forming die 30 without being cooled. In the molding, the protrusion 8a on the outer circumferential surface of the metal bush 8 is sandwiched between the two preforms 25, and the two are placed in the tooth forming die 30. The mold is clamped in the tooth forming die 30, and the preform 25 and the metal bush 8 are heated and compressed. This forms a molded product 40 as a second intermediate body shown in FIG. 6(b).

[0032] During mold clamping, for example, the molded product 40 is held at a position 10 mm before the cut-off position (target thickness) for 30 seconds, then compressed with a pressure of 100 MPa up to the cut-off position, and held in this state for approximately 6 minutes to harden the resin. Thereafter, the molded product 40 is removed from the teeth forming die 30, and any resin burrs are removed using scissors or the like. The molded product 40 is an annular object. In the molded product 40, the resin member 9 is composed of two preforms 25 that have been heated and compressed.

[0033] (gear cutting) The thickness, outer diameter, and inner diameter of the molded product 40 are machined to the specified dimensions by lathe processing. The molded product 40 is washed, and the outer periphery of the molded product 40 is subjected to gear cutting processing. Examples of gear cutting processing that can be applied include processing using a hobbing machine or a shaving machine. As a result, a tooth profile 9a (see FIG. 1) is formed on the outer periphery of the resin member 9 in the molded product 40. This completes the manufacture of the resin gear 1.

[0034] As described above, in the manufacturing method according to the present embodiment, the raw material 5 is mixed for a predetermined time by the mixer 10, whereby the resin powder 2 is adhered to the surface of the wet fibers 3 including the first fibers 3P which are para-aramid fibers and the second fibers 3M which are meta-aramid fibers, and the resin gear molding material 6 can be formed. Here, if the first fibers 3P having a fiber length shorter than 3 mm±1 mm are used, the formed resin gear molding material 6 is likely to become small powder. If the first fibers 3P having a fiber length longer than 3 mm±1 mm are used, the formed resin gear molding material 6 is likely to become large lumps. Therefore, by using the first fibers 3P having a fiber length of 3 mm±1 mm, the formed resin gear molding material 6 is prevented from becoming small powder or large lumps, and the resin gear molding material 6 can be easily handled when manufacturing the resin gear 1.

[0035] Furthermore, by using the second fibers 3M having a fiber length longer than 3 mm±1 mm, which is the fiber length of the first fibers 3P, the following findings can be obtained compared to a comparative example in which the second fibers 3M having a fiber length longer than 3 mm±1 mm are used. That is, as shown in FIG. 7(a), in a resin gear 1R manufactured using a conventional molding material, the fiber orientation tends to be an irregular wavy orientation H1. In this case, as shown in FIG. 8(a), the load direction L of the load that causes bending crosses the wavy orientation H1 that extends in a wavy shape. In contrast, as shown in FIG. 7(b), in a resin gear 1 manufactured using a resin gear molding material 6, the fiber orientation H2 tends to be linear compared to the wavy orientation H1. In this case, as shown in FIG. 8(b), the load direction L of the load that causes bending tends to cross the fiber orientation H2 perpendicularly. The fiber orientation H2 approaches a stacked orientation and tends to extend straight along the direction perpendicular to the load direction L of the load that causes bending. Therefore, by using the second fibers 3M having a fiber length longer than the fiber length of the first fibers 3P, it is possible to improve the bending strength of the manufactured resin gear 1 (hereinafter, simply referred to as "bending strength").

[0036] Therefore, the manufacturing method according to this embodiment makes it possible to obtain a resin gear molding material 6 that can increase the strength of the resin gear 1 and is easy to handle. Fig. 7(a) is a photograph showing an enlarged cross section of the resin gear 1R, Fig. 7(b) is a photograph showing an enlarged cross section of the resin gear 1, Fig. 8(a) is a schematic perspective view of the resin gear 1R, and Fig. 7(b) is a schematic perspective view of the resin gear 1.

[0037] In the method for producing a resin gear molding material 6 according to this embodiment, the fiber length of the second fibers 3M is at least twice as long as the fiber length of the first fibers 3P. In this case, the fiber orientation H2 of the produced resin gear 1 approaches the laminated orientation even more, and the resin gear 1 is more likely to extend straight in the direction perpendicular to the load direction L of the load that causes bending. This makes it possible to further improve the bending strength of the produced resin gear 1.

[0038] In the method for producing the resin gear molding material 6 according to this embodiment, the fiber length of the second fibers 3M is 6 mm±1 mm. In this case, the bending strength of the produced resin gear 1 is further improved, and at least a part of the formed resin gear molding material 6 is granulated to an appropriate size, making the resin gear molding material 6 easier to handle.

[0039] In the method for producing a resin gear molding material 6 according to this embodiment, a mixer 10 has a mixing pan 12 that contains the raw materials 5, and a rotor 13 that is disposed in the mixing pan 12 and stirs the raw materials 5. By using such a mixer 10, it becomes possible to efficiently mix the raw materials 5 to achieve the above-mentioned effects.

[0040] In the method for producing the resin gear molding material 6 according to this embodiment, the fiber volume fraction of the raw material 5 is 40 volume % or more. In this case, the bending strength of the produced resin gear 1 can be further improved. The strength of the resin gear 1 can be further increased.

[0041] In the method for producing the resin gear molding material 6 according to this embodiment, the ratio of the second fibers 3M in the wet fibers 3 is 50% by weight or more. In this case, the above-mentioned effect of obtaining the resin gear molding material 6 that can increase the strength of the resin gear 1 and is easy to handle can be effectively achieved.

[0042] In the method for producing a plastic gear 1 according to this embodiment, the plastic gear molding material 6 produced by the above-mentioned method is used for molding. This makes it possible to increase the strength of the plastic gear 1 and to facilitate handling of the plastic gear molding material 6 when producing the plastic gear 1.

[0043] Next, in order to evaluate the bending strength of the resin gear 1 manufactured using the resin gear molding material 6, a verification test was carried out to evaluate the bending strength of a test piece manufactured using the resin gear molding material 6. The following will explain the results.

[0044] In the demonstration test, first, a plurality of types of resin gear molding materials 6 are manufactured by the above-mentioned manufacturing method for the resin gear molding material 6. Specifically, a plurality of types of raw materials 5 having different fiber lengths of the second fibers 3M between 3 mm and 6 mm, a plurality of types of raw materials 5 having different fiber volume fractions between 40 volume % and 60 volume %, and a plurality of types of raw materials 5 having different specifications (e.g., the fiber length of the first fibers 3P) are used to manufacture the plurality of types of resin gear molding materials 6.

[0045] For each of the multiple types of resin gear molding materials 6 produced, a test piece having a width of, for example, 25 mm, length of, and thickness of, 6 mm is produced. When producing the test pieces, the resin gear molding material 6 is premolded to form a premolded body for the test piece. Specifically, as shown in FIG. 9, a test piece molding die 120 including a lower die 120B and an upper die 120T is prepared, and the test piece molding die 120 is preheated to, for example, 80°C. The lower die 120B has a rectangular plate-shaped cavity 121. The upper die 120T has a rectangular columnar protrusion 122 that fits into the cavity 121.

[0046] The required amount of resin gear molding material 6 is weighed out and uniformly filled into cavity 121 of lower die 120B. After filling, force is applied to upper die 20T using a press or the like to pressurize resin gear molding material 6. Pressing conditions are, for example, such that the filled resin gear molding material 6 is pressed at a pressure of 70 MPa for 10 seconds. In this way, a test piece preform is formed by preforming resin gear molding material 6. The test piece preform is then removed from test piece molding die 120.

[0047] The test piece molding die 120 is heated to 200±5°C. The test piece preform is dried in a dryer at 90°C for 2 hours. The dried test piece preform is molded into the test piece molding die 120 heated to 200°C without being cooled and at a temperature of 90°C. Immediately after molding, the test piece preform is pressed with a press or the like. The pressing conditions are, for example, conditions under which the test piece preform is pressed at a pressure of 70 MPa. Five seconds after pressing, the pressure is reduced to 0 MPa to degas, and the test piece preform is pressed again at 70 MPa for five minutes. This molds the test piece. The molded test piece is removed from the test piece molding die 120, and any resin burrs on the test piece are removed using scissors or the like.

[0048] Next, a bending test is performed on each of the multiple test pieces produced. The bending test is in accordance with the test method for bending strength and bending modulus described in "JIS K 6911 General test method for thermosetting plastics". The results of the bending strength obtained by the bending test, evaluated using an experimental design method, are shown in Figure 10(a) and Figure 10(b).

[0049] As shown in FIG. 10(a), it can be seen that the bending strength tends to increase as the fiber volume fraction of raw material 5 increases. When the fiber volume fraction of raw material 5 is between 40 volume % and 60 volume %, it can be seen that the bending strength increases proportionally as the fiber volume fraction increases. When the fiber volume fraction of raw material 5 is at least 40 volume %, the bending strength can clear the standard for resin gear 1 (e.g., 210 MPa). Therefore, it is preferable that the fiber volume fraction of raw material 5 is 40 volume % or more. This tendency can be seen in the relationship between the fiber volume fraction of raw material 5 and impact strength (kJ / m 2 ) trends are similar.

[0050] As shown in FIG. 10(b), it can be seen that the bending strength tends to increase as the fiber length of the second fibers 3M of raw material 5 increases. It can be seen that when the fiber length of the second fibers 3M of raw material 5 is between 3 mm and 6 mm, the bending strength increases proportionally as the fiber length increases. When the fiber length of the second fibers 3M of raw material 5 is twice that of the first fibers 3P (6 mm), the bending strength can fully clear the standard for the resin gear 1. Therefore, it is preferable that the fiber length of the second fibers 3M is at least twice that of the first fibers 3P, and it is preferably 6 mm or longer. This tendency can be seen in the relationship between the fiber length of the second fibers 3M of raw material 5 and the impact strength (kJ / m 2 ) trends are similar.

[0051] In a demonstration test using an experimental design method, the fiber volume fraction and the fiber length of the second fibers 3M are factors that have a large effect on the bending strength. The fiber length of the first fibers 3P is a factor that has a small effect on the bending strength. For example, even if the fiber length of the first fibers 3P is changed between 3 mm and 6 mm, there is almost no change in the bending strength. Note that even when the fiber length of the second fibers 3M is in the range longer than 3 mm and shorter than 6 mm, the bending strength can clear the standard for the resin gear 1.

[0052] Although the embodiments have been described above, one aspect of the present invention is not limited to the above-described embodiments.

[0053] In the above embodiment, in the step of mixing the raw material 5 with the mixer 10 to form the resin gear molding material 6, water may be added to the raw material 5 during mixing using a sprayer or the like. This makes it possible to adjust the moisture content of the raw material 5 and to prevent the resin powder 2 from falling off the surface of the wet fibers 3. In the above embodiment, the fiber lengths of the first fibers 3P and the second fibers 3M contained in the raw material 5 may vary by ±1 mm from a nominal value, or may have a distribution that is longer than the nominal value by about 0.1 mm to 0.3 mm based on the results of actual measurement of the fiber lengths using a CCD camera.

[0054] In the above embodiment, instead of the wet fiber 3, a fiber and water that realize the wet fiber 3 may be used. In the above embodiment, the para-aramid fiber used for the first fiber 3P is not particularly limited, and various para-aramid fibers can be used. In the above embodiment, the meta-aramid fiber used for the second fiber 3M is not particularly limited, and various meta-aramid fibers can be used. In the above embodiment, the ratio of the second fiber 3M in the wet fiber 3 is set to 50% by weight or more, but is not limited thereto and may be less than 50% by weight. However, the smaller the ratio of the second fiber 3M, the weaker the strength of the resin gear 1 may be, and if the ratio of the second fiber 3M in the wet fiber 3 is less than 50% by weight, the more likely it is that the bending strength will not reach the standard.

[0055] In the above embodiment, the resin gear 1 may include an elastic member provided between the metal bushing 8 and the resin member 9 to attenuate impact. In the above embodiment, the resin gear 1 is a spur gear, but the resin gear 1 may be a helical gear or the like. In the present invention, the configurations of the above embodiment and the above modified examples may be appropriately combined. Various modifications of the present invention are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0056] 1...resin gear, 2...resin powder, 3...wet fiber, 3P...first fiber, 3M...second fiber, 5...raw material, 6...molding material for resin gear, 9...resin part, 10...mixer, 12...mixing pan (container), 13...rotor (agitating blade).

Claims

1. A method for producing a molding material for a resin gear, comprising the steps of: A first step of preparing a raw material including a thermosetting resin powder and a wet fiber or a fiber and water that realizes the wet fiber; a second step of mixing the raw materials for a predetermined time in a mixer to form a resin gear molding material that is a fiber ball having a three-dimensional shape; The wet fiber or fibers include a first fiber that is a para-aramid fiber and a second fiber that is a meta-aramid fiber, The fiber length of the first fibers is 3 mm±1 mm; a fiber length of the second fibers is longer than a fiber length of the first fibers and is at least twice as long as the fiber length of the first fibers.

2. 2. The method for producing a resin gear molding material according to claim 1, wherein the second fibers have a fiber length of 6 mm±1 mm.

3. The mixer comprises: A container for containing the raw material; 2. The method for producing a resin gear molding material according to claim 1, further comprising: a stirring blade disposed in the container for stirring the raw material.

4. 4. The method for producing a resin gear molding material according to claim 1, wherein the fiber volume fraction of the raw material is 40 volume % or more.

5. 5. The method for producing a resin gear molding material according to claim 1, wherein a ratio of the second fibers in the wet fibers or the fibers is 50% by weight or more.

6. A method for producing a resin gear including an annular resin member and a metal bushing, using a resin gear molding material produced by the method for producing a resin gear molding material according to any one of claims 1 to 5, comprising the steps of: filling a mold with the resin gear molding material and applying pressure to form an annular first intermediate body; placing the first intermediate body and the metal bushing in a mold and compressing them by heating to form an annular second intermediate body; and forming a tooth profile on an outer periphery of the second intermediate body.

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