Manufacturing method of gear

Abstract

To obtain a manufacturing method of a gear which enables manufacturing of a gear, which includes a body and an outer periphery side tooth part integrally formed and is lightweight compared to conventional gears, without causing damage of reinforced fibers, or to obtain a manufacturing method of a gear which can manufacture the gear with processing accuracy maintained while inhibiting deterioration of strength without using reinforced fibers.SOLUTION: The invention relates to a method for manufacturing a gear 100. The gear includes: a body 110 to which a rotary shaft body is coupled; and a tooth part 120 provided at an outer periphery of the body and including a plurality of teeth. The method includes: a molding step in which the body and the tooth part are integrally molded by injection molding of a resin so that these components include reinforced fibers or a circular disc member including the body and a ring-shaped outer periphery part at the outer periphery side is formed by injection molding of a resin including a filler without using reinforced fibers; and a cutting step in which cutting is performed in the ring-shaped outer periphery part molded in the molding step to form the plurality of teeth forming the tooth part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a resin gear. [Background technology]

[0002] Gears are used in a variety of mechanical devices. For example, in electric power steering devices for automobiles, the rotation of an electric motor for steering assistance is reduced through a reduction gear and the output (rotational force) is amplified and transmitted to the steering mechanism, thereby providing torque assist for the operation of the steering mechanism operated by the driver.

[0003] The reducer generally used is equipped with a worm and a worm wheel that mesh with each other. The worm wheel is generally manufactured, for example, by forming an annular resin member on the outer periphery of an iron sleeve by injection molding (insert molding) or the like, and then forming teeth on the outer periphery of the resin member by cutting or the like.

[0004] Here, the resin member is formed of, for example, polyamide (PA6, PA66, PA46, etc.), aromatic polyamide, polyacetal, PEEK, PPS, or the like.

[0005] However, in recent years, there has been a demand to further reduce the weight of automotive parts in response to demands for reducing environmental impact, and because the iron sleeve of the worm wheel accounts for a large proportion of the weight of an electric power steering device, it is necessary to reduce the weight of the entire worm wheel, including the core (iron sleeve), while maintaining the necessary strength and rigidity.

[0006] In recent years, fiber-reinforced composite materials, which are lightweight resin materials with high strength and rigidity, have been increasingly used in automobile parts.

[0007] Examples of fiber-reinforced composite materials include CFRP (Carbon Fiber Reinforced Plastics) materials, which use carbon fiber as the reinforcing fiber and thermosetting resin as the resin, and CFRTP (Carbon Fiber Reinforced Thermo Plastics) materials, which use thermoplastic resin as the resin.

[0008] In order to reduce the weight of gears such as worm wheels by using such fiber-reinforced composite materials, for example, the following methods can be considered. (1) One method is to wind prepreg (i.e., an intermediate material in which a sheet of reinforced fibers is impregnated with a thermosetting resin) into a circular shape, and then use sheet winding molding to cause a curing reaction of the thermosetting resin to produce a disk-shaped molded body made of fiber-reinforced composite material that corresponds to the overall shape of the gear, and then cut or otherwise process the outer periphery to form the teeth. Here, the disk-shaped molded body is composed of a main body on the inner periphery and teeth on the outer periphery. (2) Another method is to produce a sleeve (main body on the inner circumference) made of a fiber-reinforced composite material by the above-mentioned sheet winding molding, and then form a circular resin member (tooth portion on the outer circumference) on the outer circumference of this sleeve by insert molding or the like in a conventional manner, and further form teeth by cutting or the like on the outer circumference of the insert-molded resin member (Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2001-304379 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the method (1), when the teeth are formed by cutting, the continuous reinforcing fibers may be cut or the resin may peel off from the reinforcing fibers, causing the damaged parts of the reinforcing fibers to become the source of fracture, resulting in a decrease in the impact resistance and mechanical strength of the gear.

[0011] On the other hand, in the gears formed by method (2), the adhesive joint between the sleeve (main body on the inner circumference) and the teeth (outer circumference) does not have sufficient reliability, thermal shock resistance, etc., and when the outer circumference of the sleeve in contact with the teeth is knurled, blasted, etched, etc. in order to improve these characteristics and ensure that the teeth and the sleeve do not come off or rotate, etc., the continuous reinforcing fibers are cut or the resin and the reinforcing fibers are peeled off, and the damaged parts of the reinforcing fibers become the source of destruction, which reduces the impact resistance and mechanical strength of the gear, just as in method (1).

[0012] The present invention aims to provide a method for manufacturing a gear that can produce a gear having an inner body portion and an outer tooth portion integrally formed therewith, which is lighter than conventional gears, by using reinforcing fibers without incurring damage to the fibers.

[0013] The present invention aims to provide a method for manufacturing a gear that can produce a gear having an inner body portion and an outer tooth portion integrally formed therewith, which is lighter than conventional gears, without using reinforcing fibers, while maintaining processing precision and suppressing a decrease in strength. [Means for solving the problem]

[0014] The present invention provides the following:

[0015] (Item 1) 1. A method of manufacturing a gear, comprising the steps of: The gear is a main body to which the rotating shaft is coupled; a teeth portion including a plurality of teeth provided on an outer periphery of the main body portion; Equipped with The method comprises: A step of integrally molding the body portion and the teeth portion by injection molding of resin so that they contain reinforcing fibers. A method for manufacturing a gear, comprising:

[0016] (Item 2) 1. A method of manufacturing a gear, comprising the steps of: The gear is a main body to which the rotating shaft is coupled; a teeth portion including a plurality of teeth provided on an outer periphery of the main body portion; Equipped with The method comprises: forming a disk member including the main body portion and a ring-shaped outer circumferential portion located on the outer circumferential side of the main body portion by injection molding of a resin including a filler without using reinforcing fibers; a cutting process for forming a plurality of teeth constituting the tooth portion by performing cutting processing on the ring-shaped outer circumferential portion of the disk member; A method for manufacturing a gear, comprising: Effect of the Invention

[0017] According to the present invention, a gear manufacturing method can be obtained that can manufacture a gear having an inner body portion and an outer tooth portion integrally formed therewith, which is lighter than conventional gears, by using reinforcing fibers without incurring damage to the fibers.

[0018] According to the present invention, a method for manufacturing a gear can be obtained that can produce a gear having an inner body portion and an outer tooth portion formed as one unit, which is lighter than conventional gears, without using reinforcing fibers, while maintaining processing precision and suppressing a decrease in strength. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a diagram for explaining the method for manufacturing a gear according to the first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a specific example of a gear-shaped fiber body 100a used in the gear manufacturing method of the first embodiment. [Diagram 3] FIG. 6 is a diagram for explaining a method for manufacturing a gear according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described below.Unless otherwise specified, it should be understood that the terms used in this specification are used in the sense that they are commonly used in the field.Therefore, unless otherwise defined, all technical terms and scientific and technical terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this invention belongs.In the case of conflict, this specification (including definitions) shall prevail.

[0021] In this specification, the term "about" refers to a range of ±10% of the subsequent number.

[0022] The object of the present invention is to provide a method for manufacturing a gear in which a main body on the inner circumference side and a tooth portion on the outer circumference side are integrally formed, and which is lighter than conventional gears, by using reinforcing fibers without damaging the reinforcing fibers. 1. A method of manufacturing a gear, comprising the steps of: The gears are a main body to which the rotating shaft is coupled; a teeth portion including a plurality of teeth provided on an outer periphery of the main body portion; Equipped with The method is: A process of integrally molding the body and teeth by resin injection molding so that they contain reinforcing fibers. The above-mentioned problems are solved by providing a gear manufacturing method including the steps of:

[0023] In the manufacturing method of gears configured in this manner, the gear body and the outer teeth are molded integrally from resin, so that the reliability of the adhesive joint between the gear body and the outer teeth is improved compared to conventional methods, and because the entire gear is made of resin, it is lighter than conventional methods.

[0024] Furthermore, reinforcing fibers are contained throughout the entire gear, and not only the main body on the inside of the gear but also the tooth portion where the teeth are formed is structured with reinforcing fibers.

[0025] Moreover, in this gear manufacturing method, even the gear teeth are formed by resin molding, and there is no cutting step for forming the teeth by cutting the tooth portion, so the reinforcing fibers are not damaged.

[0026] In this manner, the manufacturing method of a gear of the present invention is not particularly limited as long as it is a method in which the molding containing the reinforcing fibers is not subjected to cutting after the resin molding containing the reinforcing fibers is performed. Other configurations are not limited, and the method is not particularly limited.

[0027] For example, in the process of integrally molding the main body and the teeth so that they contain reinforcing fibers by resin injection molding, a three-dimensional fabric made of reinforcing fibers woven in a three-dimensional shape may be placed in the hollow area (resin injection area) in the molding die and filled with resin, or plate-shaped bodies made of reinforcing fibers may be stacked to a predetermined thickness and filled with resin.

[0028] Another object of the present invention is to provide a method for manufacturing a gear in which an inner circumferential side main body and an outer circumferential side tooth portion are integrally formed, and which is lighter than conventional gears, while maintaining machining accuracy and preventing a decrease in strength without using reinforcing fibers. 1. A method of manufacturing a gear, comprising the steps of: The gears are a main body to which the rotating shaft is coupled; a teeth portion including a plurality of teeth provided on an outer periphery of the main body portion; Equipped with The method is: A step of forming a disk member (molded body) including a main body portion and a ring-shaped outer peripheral portion located on the outer periphery side of the main body portion by injection molding of a resin including a filler without using reinforcing fibers; a cutting process for forming a plurality of teeth constituting the tooth portion by performing cutting processing on the ring-shaped outer periphery of the disk member; The above-mentioned problems are solved by providing a gear manufacturing method including the steps of:

[0029] In the manufacturing method of a gear having such a configuration, a disk member including a main body and a ring-shaped outer peripheral portion located on the outer periphery of the main body is formed by injection molding of a resin containing a filler without using reinforcing fibers, and then the ring-shaped outer peripheral portion of the disk member is cut.Therefore, it is possible to manufacture a gear without using reinforcing fibers while maintaining processing precision by cutting while suppressing a decrease in strength by the filler.

[0030] Therefore, the gear manufacturing method of the present invention is not limited to any other configuration as long as it involves cutting a circular plate member (molded body) molded from resin without using reinforcing fibers to form gear teeth.

[0031] For example, the molding resin may be a thermoplastic resin or a thermosetting resin.

[0032] Specific examples of the filler include fibrous fillers such as glass fibers and carbon fibers, plate-like fillers such as glass flakes, and finely reinforced fillers such as carbon nanotubes and carbon nanofibers.

[0033] In the following embodiments, a manufacturing method for a gear using reinforcing fibers (not including a cutting step) will be described in embodiment 1, and a manufacturing method for a gear using a filler instead of reinforcing fibers (including a cutting step) will be described in embodiment 2.

[0034] (Embodiment 1) FIG. 1 is a diagram for explaining a method for manufacturing a gear according to a first embodiment of the present invention, and shows how a gear is produced in a molding die by injection molding.

[0035] This gear 100 has a main body 110, which is the inner peripheral portion, and a teeth portion 120, which is the portion located on the outer peripheral side of the main body 110. Here, a fixing hole (shaft fixing hole) 101 for fixing a rotating shaft, such as a rotating shaft, is formed in the center of the main body 110, and a plurality of teeth 121 that constitute the gear 100 are formed in the teeth portion 120 along its outer peripheral surface.

[0036] As shown in FIG. 1, this gear 100 is formed by a single injection molding using a molding die 10, with a main body portion 110 and a teeth portion 120 being integrally molded from resin so that each contains reinforcing fibers.

[0037] Here, the reinforcing fiber is carbon fiber or the like. The resin is a thermosetting resin or a thermoplastic resin. For example, the resin containing carbon fiber may be the above-mentioned CFRP material (a fiber-reinforced composite material containing carbon fiber in a thermosetting resin) or the above-mentioned CFRTP material (a fiber-reinforced composite material containing carbon fiber in a thermoplastic resin).

[0038] Next, a method for manufacturing this gear 100 will be described.

[0039] A pair of upper and lower dies, a lower die 11 and an upper die 12, are prepared for injecting resin for injection molding this gear 100, and are arranged opposite each other so that a hollow region (resin injection region) Sp1 is formed by these dies 11 and 12. At this time, a gear-shaped fibrous body 100a made of reinforcing fibers is placed in the resin injection region Sp1.

[0040] Here, the resin injection region Sp1 is a region having a shape that matches the outer shape of the gear 100.

[0041] The gear-shaped fiber body 100a has an outer shape that is substantially identical to the outer shape of the gear 100, and is entirely made of reinforcing fibers so as to be impregnated with resin.

[0042] Specific examples of the gear-shaped fibrous body 100a include the following.

[0043] FIG. 2 shows specific examples of a gear-shaped fiber body 100a used in the gear manufacturing method of embodiment 1, and FIG. 2(a) and FIG. 2(b) show first and second specific examples of the gear-shaped fiber body 100a.

[0044] A first specific example of the gear-shaped fiber body 100a is a three-dimensional fabric 100a1 in which reinforcing fibers are woven in a three-dimensional shape, as shown in FIG. 2(a).

[0045] A second specific example of the gear-shaped fiber body 100a is a laminate 100a2 formed by laminating a plurality of gear-shaped perforated plate-like bodies (e.g., three plate-like bodies A1 to A3) made of reinforcing fibers in the thickness direction to a predetermined thickness as shown in Fig. 2(b). Examples of the perforated plate-like body include a woven fabric in which reinforcing fibers are woven into a gear-shaped perforated plate-like body, and a sheet-like woven fabric or a unidirectional material punched into a gear-shaped perforated plate-like body.

[0046] Examples of the reinforcing fibers forming the gear-shaped fiber body 100a include various fibers such as the above-mentioned carbon fibers, glass fibers, and aramid fibers.

[0047] In particular, carbon fiber is preferred in order to provide as high strength and rigidity as possible to the gear 100. In order to further improve such effects, carbon fiber having a tensile strength of 3000 MPa or more and a tensile modulus of elasticity of 200 GPa or more is preferred.

[0048] In order to ensure good adhesion with the resin, the surface of the carbon fiber is preferably treated with a sizing agent such as a urethane-, epoxy-, acrylic- or bismaleimide-based agent.

[0049] The lower mold 11 is formed with a resin injection port 11a for filling the mold 10 with resin, and the upper mold 12 is formed with an exhaust port 12a for venting air when the resin is filled.

[0050] With the gear-shaped fiber body 100a thus positioned within the resin filling region formed by the hollow regions of the pair of molds 11 and 12, the molding mold 10 is filled with heated resin, for example, thermoplastic resin.

[0051] At this time, the thermoplastic resin fills the resin filling region in the molding die 10 and simultaneously enters into the gaps between the fibers of the gear-shaped fiber body 100a disposed in the resin filling region.

[0052] Thereafter, the heated thermoplastic resin is cooled and the molded body is removed from the molding die 10, yielding a gear 100 having a plurality of teeth 121 formed thereon.

[0053] Here, the resin can be filled into the resin injection area of ​​the molding die 10, for example, by injection molding, i.e., by injecting the resin in a fluid state that has been heated and melted in an injection molding machine through a resin injection port (gate) 11a.

[0054] As the resin injection port 11a, any type of gate can be used, such as a pin gate connected to multiple points in the resin injection area of ​​the lower mold 11 or the upper mold 12, or a disk gate connected to the entire circumference of the resin injection area.

[0055] When the resin is a thermoplastic resin as described above, the filled resin is cooled and solidified to form a molded body, whereas when the resin is a thermosetting resin, the filled resin is heated and cured to form a molded body.

[0056] As the thermoplastic resin, various thermoplastic resins that can be injection molded can be used. In particular, engineering plastics such as polyamide (PA6, PA66, PA46, etc.), which are widely used in the mechanical field, and super engineering plastics such as aromatic polyamide (PA6T, PA9T, PPA), polyacetal, PEEK, PEK, and PPS are preferable.

[0057] As the thermosetting resin, various types of thermosetting resins that can be injection molded and have a short curing time can be used, and examples of such thermosetting resins include phenolic resins (resol type, novolac type), unsaturated polyester resins, etc. Also, epoxy resins that have been given quick curing properties instead of tackiness, flexibility, etc. can be used.

[0058] The resin gear 100 produced in this manner has the main body 110 and the outer peripheral teeth 120 molded integrally from resin, so that the reliability of the adhesive joint between the main body 110 and the outer peripheral teeth 120 is improved compared to conventional gears, and since the entire gear is made of resin, it is lighter than conventional gears.

[0059] Furthermore, reinforcing fibers are contained throughout the gear 100, and not only the main body 110 on the inside of the gear 100 but also the tooth portion 120 on which the teeth 121 are formed are structured to be reinforced with reinforcing fibers.

[0060] Furthermore, in the method for manufacturing gear 100 of this embodiment 1, even teeth 121 of gear 100 are formed by resin molding, and there is no cutting step for forming teeth 121 by cutting the tooth portion, so the reinforcing fibers are not damaged.

[0061] It is preferable to blend a filler into the resin used in the injection molding, because blending a filler allows the filler to permeate between the reinforcing fibers that form the gear-shaped fiber body 100a, thereby further improving the strength and rigidity of the entire gear 100.

[0062] Examples of the filler include one or more of fibrous fillers such as glass fibers and carbon fibers, plate-like fillers such as glass flakes, and finely reinforcing fillers such as carbon nanotubes and carbon nanofibers.

[0063] The melt flow rate of the resin itself when it does not contain the above filler, or the melt flow rate of the resin when it contains a filler and is injection molded (when melted) is preferably 30 g / 10 min or more, particularly 50 g / 10 min or more.

[0064] If the melt flow rate is below this range, the resin, or the resin and filler, cannot be impregnated into the gear-shaped fiber body 100a well and without gaps by injection molding, which may result in unimpregnated resin areas that could cause damage and reduce the mechanical strength of the gear 100, or the resin may not be able to fill every corner of the resin injection area sufficiently, resulting in defective molding.

[0065] In order to adjust the melt flow rate to the above range, a viscosity reducer, a dispersant, an amorphous resin for reducing the solidification rate, etc. may be appropriately added to the resin.

[0066] In particular, when using a resin with high melt viscosity during injection molding, the inside of the molding die 10 may be evacuated and injection molding may be performed under reduced pressure in order to ensure that the resin, or the resin and filler, are well impregnated into the gear-shaped fiber body 100a without any gaps and to ensure that every corner of the resin injection area is sufficiently filled.

[0067] In addition, in the manufacturing method of this example, a liquid precursor of the resin or liquid resin can be filled into the resin injection region Sp1 by resin injection molding such as RTM (resin transfer molding) or VaRTM (vacuum resin transfer molding).

[0068] Examples of liquid precursors of resins used in these methods include those obtained by compounding a polymerization catalyst, a polymerization promoter, a reaction initiator, etc. with a monomer or oligomer that is the basis of a thermoplastic resin, such as monomer cast nylon.

[0069] As the liquid resin, a liquid thermosetting resin that can be injected into the molding die 10 by resin injection molding and has a short curing time can be used. As such a thermosetting resin, the above-mentioned phenolic resin (resol type, novolac type), unsaturated polyester resin, or epoxy resin that has been given quick-curing properties instead of tackiness or flexibility, which is liquid before curing, or that has been made liquid by blending a reactive diluent, etc., can be used.

[0070] Furthermore, the liquid resin precursor or liquid resin may contain a similar filler for the same reasons as above.

[0071] Such a liquid precursor or resin is injected into the molding die 10 by, for example, clamping force plus pump pressure in the RTM method, and is suction-injected by drawing a vacuum inside the molding die 10 in the VaRTM method.

[0072] In the case of a liquid precursor, when heated as necessary, the monomers etc. undergo a polymerization reaction to produce a resin that solidifies to form a molded product (gear). In the case of a liquid thermosetting resin, after filling, the resin is heated to cause a curing reaction to form a molded product (gear).

[0073] (Embodiment 2) Next, a method for manufacturing the gear 200 according to the second embodiment of the present invention will be described.

[0074] FIG. 3 is a diagram for explaining a method for manufacturing a gear according to a second embodiment of the present invention, showing how a gear is manufactured through a process including injection molding and cutting.

[0075] Like the gear 100 of the first embodiment, this gear 200 has a main body 210, which is an inner peripheral portion, and a teeth portion 220, which is a portion located on the outer peripheral side thereof. Here, a fixing hole (shaft body fixing hole) 201 for fixing a rotating shaft such as a rotating shaft is formed in the center of the main body 210, and a plurality of teeth 221 constituting the gear 200 are formed in the teeth portion 220 along its outer peripheral surface.

[0076] The resin constituting this gear 200 does not contain the reinforcing fibers found in gear 100 of embodiment 1, and differs from gear 100 of embodiment 1 in that the multiple teeth 121 constituting tooth portion 220 are formed by cutting.

[0077] For example, the resin constituting the gear 200 may be polyamide (PA6, PA66, PA46, etc.), aromatic polyamide, polyacetal, PEEK, PEK, PPS, etc. The resin constituting the gear 200 may contain any of the above-mentioned fillers instead of reinforcing fibers.

[0078] Next, a method for manufacturing this gear 200 will be described.

[0079] A pair of upper and lower dies, a lower die 21 and an upper die 22, are prepared for injecting resin for injection molding the disk member 200a that is the base of this gear 200, and these dies 121 and 22 are arranged opposite each other so as to form a hollow region (resin injection region). At this time, the resin injection region is left empty.

[0080] The lower mold 21 is formed with a resin injection port 21a for filling the mold 20 with resin, and the upper mold 22 is formed with an exhaust port 22a for venting air when the resin is filled.

[0081] The heated molding resin is filled into the resin injection region Sp2 formed by combining the pair of lower mold 21 and upper mold 22 that constitute molding die 20 in this manner. Here, the molding resin may be a thermoplastic resin or a thermosetting resin. At this time, the molding resin fills the resin filling region in molding die 20. Here, the resin contains a filler as described above.

[0082] By blending the filler, it is possible to ensure high toughness, strength, abrasion resistance, impact resistance, and the like of the teeth portion 220 while maintaining the favorable flexibility of the teeth portion 220 that does not contain reinforcing fibers.

[0083] Thereafter, the heated molding resin (for example, thermoplastic resin) is cooled, and the molded body is removed from the molding die 20, whereby the disk member 200a that is the base of the gear 200 is obtained.

[0084] This disk member 200a is a member composed of a main body portion 210 on the inner circumference side and a ring-shaped outer peripheral portion 220a on the outer circumference side thereof, and the ring-shaped outer peripheral portion 220a is the part that is subject to cutting processing to form the teeth 221.

[0085] Thereafter, the ring-shaped outer peripheral portion 220 a is subjected to a cutting process to form a plurality of teeth 221 that constitute the gear 200 .

[0086] By producing the resin gear 200 in this manner, the main body 210 and the ring-shaped outer circumferential portion 220a can be integrally molded, and the main body 210 and the ring-shaped outer circumferential portion 220a can be firmly joined together.

[0087] Furthermore, since the teeth 221 constituting the toothed portion 220 are formed by cutting the ring-shaped outer circumferential portion 220a, the machining precision of the teeth 221 of the gear 200 can be improved.

[0088] Furthermore, because the gear 200 made of resin contains filler, it is possible to prevent a decrease in the strength of the gear caused by not using reinforcing fibers. [Industrial Applicability]

[0089] The present invention is useful because it can provide a method for manufacturing a gear in which the main body and the outer peripheral teeth are formed as one unit and which is lighter than conventional gears, by using reinforcing fibers without incurring damage to the gear, or by which a gear can be manufactured without using reinforcing fibers, while maintaining processing precision and suppressing a decrease in strength. [Explanation of symbols]

[0090] 10, 20 Molding mold 11, 21 Upper mold 11a, 21a Exhaust port 12, 22 Lower mold 12a, 22a resin inlet 100, 200 gears 100a Gear-shaped fiber body 101,201 Rotating shaft fixing hole 110, 210 Main body 120, 220 teeth 121, 221 teeth 200a Disc member 220a Ring-shaped outer periphery

Claims

1. 1. A method of manufacturing a gear, comprising the steps of: The gear is a main body to which the rotating shaft is coupled; a teeth portion including a plurality of teeth provided on an outer periphery of the main body portion; Equipped with The method comprises: A step of integrally molding the body portion and the teeth portion by injection molding of resin so that they contain reinforcing fibers. A method for manufacturing a gear, comprising:

2. 1. A method of manufacturing a gear, comprising the steps of: The gear is a main body to which the rotating shaft is coupled; a teeth portion including a plurality of teeth provided on an outer periphery of the main body portion; Equipped with The method comprises: forming a disk member including the main body portion and a ring-shaped outer circumferential portion located on the outer circumferential side of the main body portion by injection molding of a resin including a filler without using reinforcing fibers; a cutting process for forming a plurality of teeth constituting the tooth portion by performing cutting processing on the ring-shaped outer circumferential portion of the disk member; A method for manufacturing a gear, comprising:

Images