CN117425558A

CN117425558A - Method for manufacturing composite material molded article, method for manufacturing cage and rolling bearing, and method for manufacturing gear box component

Info

Publication number: CN117425558A
Application number: CN202280035135.4A
Authority: CN
Inventors: 常増卓也; 松本兼明
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2021-05-14
Filing date: 2022-05-13
Publication date: 2024-01-19

Abstract

The method for producing the composite material molded article comprises: forming a preform by removing a solvent from a solution in which reinforcing fibers having an average fiber length of 0.5mm or more and a thermosetting resin are dispersed and mixed in the solvent by papermaking; and a step of press-forming the obtained preform by using a forming die set at a temperature equal to or higher than the curing temperature of the thermosetting resin to form a composite material formed article.

Description

Method for manufacturing composite material molded article, method for manufacturing cage and rolling bearing, and method for manufacturing gear box component

Technical Field

The present invention relates to a method for producing a composite material molded article, a method for producing a cage and a rolling bearing, and a method for producing a gear case component.

Background

Generally, a cylindrical roller bearing, an angular ball bearing, or the like is used as a bearing for a spindle of a machine tool. As the cage for these bearings, a so-called plastic cage (synthetic resin cage) using a material such as a cage obtained by cutting a phenolic resin reinforced with cotton cloth, a 66 nylon resin reinforced with glass fibers or carbon fibers, a polyphenylene sulfide resin, or a polyether ether ketone resin is used. The plastic cage is lightweight, has a small centrifugal force during rotation, and has self-lubricating properties, and is therefore advantageous for high-speed rotation.

For example, patent document 1 proposes the following: the retainer body of the retainer is composed of a compression molded body of a resin material, and metal annular plates are integrally molded on both end surfaces of the retainer body, thereby enhancing the rigidity of the retainer. In addition, patent document 2 proposes the following method: the woven fabric of carbon fibers is impregnated with and coated with a thermosetting resin, and compressed in the annular axial direction, thereby forming a high-strength and high-rigidity retainer.

In addition, an electric power steering apparatus is known in which an assist output of an electric motor is transmitted to a steering mechanism of a vehicle via a reduction gear mechanism. The gear case accommodating the reduction gear mechanism of the electric power steering apparatus is composed of gear case and gear case constituent members such as a cover, and these are generally formed of a metal such as an aluminum alloy.

In recent years, in order to save resources, energy and CO for automobiles ₂ In the case of a strong demand for reduction in the drive power consumption, further weight reduction is required for the electric power steering apparatus. Accordingly, the reduction in weight of the gear case of the electric power steering apparatus has been studied, but in the realization thereof, the materials and structures forming them must be greatly changed.

For example, a gear box made of a metal is considered to be formed of a resin material having a smaller specific gravity, but the resin material has lower impact resistance, creep characteristics, and rigidity than the metal material, and it is difficult to ensure the quality equivalent to that of the conventional products by simply changing the material to the resin material. In addition, in a resin structure, it is difficult to secure dimensional stability equivalent to that of a metal structure.

In such a case, patent documents 3 and 4 disclose examples of a gear case (housing) of an electric power steering apparatus made of a resin material. In the electric power steering apparatus of patent document 3, the housing is entirely made of a resin material. In the electric power steering apparatus of patent document 4, a housing made of a resin material is covered with a metal plating film. This provides the same characteristics as the metal case, and realizes weight reduction.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-232382

Patent document 2: japanese patent application laid-open No. 2015-135153

Patent document 3: japanese patent laid-open No. 2009-298246

Patent document 4: japanese patent application laid-open No. 2012-20647

Disclosure of Invention

Technical problem to be solved by the invention

In recent machine tools, there is an increasing demand for shortening machining time by improving cutting ability, and there is a significant tendency to increase the rotational speed of the spindle. Therefore, in a rolling bearing supporting a main shaft rotating at a high speed, the centrifugal force to which the cage is subjected increases, and when the use condition becomes severe, the cage is deformed to come into contact with the outer ring, and wear is generated, or the cage may be broken due to high hoop stress.

In patent document 3, the sensor case and the gear case are all formed of a polyamide resin material or a polyamide resin filled with reinforcing fibers, and are integrated by laser welding. Therefore, in order to weld both the materials by laser welding, it is necessary to reduce the fiber content, and it is difficult to maintain physical properties such as high-temperature strength, impact resistance, creep characteristics, and rigidity for a long period of time. The case of patent document 4 is covered with a metal plating film, and the effect of preventing the environmental degradation of the material and suppressing the decrease in the case strength can be obtained, but since the strength of the resin material itself is not improved, there is a possibility that sufficient strength cannot be ensured.

Thus, there is still a problem in producing a composite molded article using reinforcing fibers.

The present invention has been made to solve the above-described problems, and a first object thereof is to provide a method for producing a composite molded article, which can improve the strength and dimensional stability of a composite molded article including reinforcing fibers and a resin.

A second object of the present invention is to provide a cage and a method for manufacturing a rolling bearing, which can maintain a good lubrication state even when used in a high-speed rotation environment, have high reliability, and can realize a long life.

A third object of the present invention is to provide a method for manufacturing a gear case component, which can achieve weight reduction and achieve durability and reliability equivalent to those of a metal case.

Means for solving the problems

The present invention is constituted by the following structure.

(1) A method of manufacturing a composite molded article, comprising:

forming a preform by removing a solvent from a solution in which reinforcing fibers having an average fiber length of 0.5mm or more and a thermosetting resin are dispersed and mixed in the solvent by papermaking; and

and a step of press-forming the obtained preform by using a forming die set to a temperature equal to or higher than the curing temperature of the thermosetting resin to form the composite molded article.

(2) A method for manufacturing a cage, wherein a cage used for a rolling bearing is manufactured by the method for manufacturing a composite molded article according to (1).

(3) A method for manufacturing a rolling bearing, wherein the rolling bearing is manufactured using the cage manufactured by the method for manufacturing a cage according to (2).

(4) A method for manufacturing a gear case component, wherein the gear case component constituting a gear case accommodating a gear mechanism is manufactured by the method for manufacturing a composite molded article according to (1).

Effects of the invention

According to the present invention, the strength and dimensional stability of a composite molded article comprising a reinforcing fiber and a resin can be improved.

Drawings

FIG. 1 is a partial cross-sectional view of a roller bearing.

Fig. 2 is a perspective view of a cage used in the roller bearing shown in fig. 1.

Fig. 3 is a partial cross-sectional view of a ball bearing.

Fig. 4 is a perspective view of a cage used in the ball bearing of fig. 3.

Fig. 5A is a process explanatory diagram for preparing a solution in which reinforcing fibers and a thermosetting resin are dispersed and mixed in a solvent.

Fig. 5B is a process explanatory diagram showing a state before the stirrer is driven in the process of preparing a solution in which reinforcing fibers and a thermosetting resin are dispersed and mixed in a solvent.

Fig. 6A is a process explanatory diagram showing a press molding process of molding the retainer.

Fig. 6B is a process explanatory diagram showing a press molding process of molding the retainer.

Fig. 7A is a process explanatory diagram showing another press forming process of forming the retainer.

Fig. 7B is a process explanatory diagram showing another press forming process for forming the retainer.

Fig. 8 is a schematic configuration diagram of the electric power steering apparatus.

Fig. 9 is a partial cross-sectional view of line IX-IX shown in fig. 8.

Fig. 10 is a partial cross-sectional view of the X-X line shown in fig. 9.

Fig. 11A is a top view showing the gearbox body with core gold in a single piece.

Fig. 11B is a top view showing the gear box cover with core gold in a single piece.

Fig. 12A is a structural view of a molded article simulating the shape of a gear box cover, and is an axial cross-sectional view of the molded article.

Fig. 12B is a structural view of a molded article simulating the shape of the gear case cover, and is a plan view of the molded article.

Fig. 13A is a process explanatory diagram showing a process of processing an integrated preform.

Fig. 13B is a process explanatory diagram showing a process of processing the integrated preform.

Fig. 13C is a process explanatory diagram showing a process of processing the integrated preform.

Fig. 14A is an explanatory diagram showing a position of cutting out a test piece from a molded article, and is a side view of the molded article.

Fig. 14B is an explanatory diagram showing a position of cutting out a test piece from a molded article, and is a plan view of the molded article.

Description of the reference numerals

11. Roller bearing (Rolling bearing)

19. 29 holder

19A ring part

19B column part

19a pocket

21. Ball bearing (Rolling bearing)

29. Retainer

29a pocket

31. Reinforcing fiber

33. Thermosetting resin

35. Solvent(s)

37. Container

39. Mixer

41. Solution

51. Punching forming die (forming die)

53. Inner diameter side die

55. Outer diameter side die

57. Base mould

59. Movable mould

59a projection

61. Gap part

63. Preform

65. Compression molded body

71. Punching forming die (forming die)

73. Outer diameter side die

73a block

80. Molded article

111. Electric motor

113. Reduction gear mechanism

115. Steering mechanism

117. Steering shaft

119. Steering shaft housing

121. Rack and pinion mechanism

123. Rack bar

125. Pinion shaft

127. Shell for rack

129. 131 universal joint

133. Gear box

135. Gear case main body (Gear case component)

137. Gear case cover (Gear case component)

139. Bolt

141. 142 resin composition

143. 144, 145, 146, 147, 149 core gold (embedding material)

148. Intermediate steering shaft

151. First rolling bearing

153. Second rolling bearing

155. Worm wheel

155a circular plate part

155b synthetic resin teeth

157. Worm shaft

159. Torque sensor

161. Rotary shaft

163. Spline joint

167. Torsion bar

169. Connecting pin

173. Gear housing

175. Third rolling bearing

177. Fourth rolling bearing

100. Electric power steering apparatus

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the cage and gear case constituent members of the rolling bearing are described as examples of the composite material molded product, but the composite material molded product is not limited thereto, and may be a molded product such as a cylindrical shape or an annular shape.

First structural example

Fig. 1 to 4 show examples of a cage and a rolling bearing manufactured by a manufacturing method of the cage and the rolling bearing. Fig. 1 is a partial sectional view of a roller bearing, and fig. 2 is a perspective view of a cage used in the roller bearing shown in fig. 1.

The roller bearing 11 shown in fig. 1, which is an example of a rolling bearing, is a cylindrical roller bearing including an outer ring 13, an inner ring 15, a plurality of rolling elements 17, and a cage 19. The cage 19 is in an outer ring guide form, and is set to rotationally guide the cage 19 by an inner diameter surface of the outer ring 13. The roller bearing 11 is also suitable for supporting a spindle rotating at a high speed, for example, a spindle of a machine tool.

As shown in fig. 2, the holder 19 has a pair of annular portions 19A opposed in the axial direction and a plurality of column portions 19B connecting the pair of annular portions 19A to each other. The region surrounded by the pair of pillar portions 19B and the pair of annular portions 19A disposed opposite each other in the circumferential direction and the pair of annular portions 19A disposed opposite each other in the axial direction becomes a plurality of rectangular pockets 19A accommodating the rolling elements 17. Each pocket 19a rotatably holds the rolling elements 17 disposed in the pocket 19a. Further, a plurality of fine irregularities may be formed at random on the guide surface 19b (surface facing the outer diameter direction) of the cage 19 and the surface 19c (surface facing the circumferential direction) in sliding contact with the rolling elements 17. These fine irregularities can be formed by various known methods. For example, a desired concave-convex shape is formed on a mold molding surface during molding, and the concave-convex shape is obtained by transfer from a mold during molding. Such irregularities inhibit damage to the inner diameter surface of the outer ring when the bearing is in sliding contact with the inner diameter surface of the outer ring during high-speed rotation.

The rolling bearing is not limited to the above-described roller bearing, and may be another type of rolling bearing such as a ball bearing.

Fig. 3 is a partial sectional view of the ball bearing, and fig. 4 is a perspective view of a cage used in the ball bearing of fig. 3.

The ball bearing 21 shown as another example of the rolling bearing is an angular ball bearing including an outer ring 23, an inner ring 25, a plurality of rolling elements 27, and a cage 29. In this case, as in the roller bearing 11 shown in fig. 1 and 2, the cage 29 has a plurality of circular pockets 29a, and the rolling elements 27 disposed in the pockets 29a are rotatably held.

In particular, in the above-described rolling bearing, the centrifugal force applied to the cage increases in a high-speed rotation environment, and wear due to contact between the cage and the outer ring, and the risk of damage to the cage due to hoop stress are liable to occur. Therefore, there is a limitation on the rotational speed that can be used.

Therefore, the cage and the method of manufacturing the rolling bearing according to the present embodiment are used to form a bearing structure that can be applied to the high-speed rotation described above, and the resin cage is formed by press-forming the preform manufactured in the forging step, so that the strength, rigidity, and the like of the cage can be improved, and abrasion and breakage due to deformation caused by centrifugal force can be suppressed. Thus, even in use in a high-speed rotation environment of the rolling bearing, reliability can be improved while maintaining a good lubrication state, and a long life can be realized. Hereinafter, a method for manufacturing a cage and a rolling bearing, which can manufacture such a cage and rolling bearing, will be described.

The method for manufacturing the cage used for the rolling bearing mainly includes the following steps.

(1) A step of preparing a solution in which reinforcing fibers having an average fiber length of 0.5mm or more and a thermosetting resin are dispersed and mixed in a solvent.

(2) And (3) removing the solvent from the solution obtained by the dispersion and mixing in (1) by papermaking to form a preform.

(3) And (3) a step of press-forming the preform obtained in (2) by using a forming die set at a temperature equal to or higher than the curing temperature of the thermosetting resin to form the retainer.

Next, each of the above steps will be described in detail.

Fig. 5A and 5B are explanatory views of steps for preparing a solution in which reinforcing fibers and a thermosetting resin are dispersed and mixed in a solvent.

As shown in fig. 5A, for example, the sheet-like reinforcing fibers 31 are put into a container 37 containing a solvent 35, and a stirrer 39 is driven. Further, for example, the thermosetting resin 33 in powder form is put into the container 37, and the mixing and the diffusion are continued by the stirrer 39. As a result, as shown in fig. 5B, the reinforcing fibers 31 are opened in the solvent 35, and a solution 41, which is a homogeneous fiber-containing slurry obtained by dispersing and mixing the reinforcing fibers 31 and the thermosetting resin 33 in the solvent, is obtained. The solvent 35 is preferably water (white water) from the viewpoints of stability, operability, and material cost, but may be a solvent such as ethanol or methanol, or a mixture thereof.

The reinforcing fiber 31 is, for example, at least one selected from carbon fiber, aramid fiber, glass fiber, cellulose fiber, polyarylate fiber, and poly-p-phenylene benzobisoxazole fiber. In particular, carbon fibers and glass fibers are preferable because they have good reinforcing properties. In addition, 2 or more kinds of reinforcing fibers selected from the above-mentioned respective fibers may be used, and the kind of the second and subsequent reinforcing fibers is not particularly limited.

The average fiber length of the reinforcing fibers 31 to be fed is preferably 0.5mm or more, more preferably 1.0mm or more. This can stably ensure the reinforcing property of the reinforcing fiber.

The amount of the reinforcing fibers 31 blended in the solution 41 is preferably, for example, 10 mass% or more and 60 mass% or less. If the amount is 10 mass% or more, the mechanical strength can be significantly improved, and if the amount is 60 mass% or less, the toughness of the material is not impaired, and the target strength and rigidity can be ensured.

The thermosetting resin 33 includes, for example, at least one resin selected from epoxy resin, bismaleimide resin, polyaminoamide resin, polyimide resin, and phenolic resin. The thermosetting resin 33 is preferably in a powder form. If the thermosetting resin 33 is in the form of powder, the reinforcing fibers 31 and the thermosetting resin 33 can be sufficiently dispersed and mixed in the subsequent papermaking step.

Next, the solvent 35 is removed from the solution 41 in which the reinforcing fibers 31 and the thermosetting resin 33 are dispersed and mixed by papermaking (paper making), thereby forming a preform. That is, in fig. 5B, the powder of the reinforcing fiber 31 and the thermosetting resin 33 is sufficiently dispersed by stirring, and then the fixing agent is added and mixed. Thereby, the reinforcing fibers 31 are bonded to the thermosetting resin 33. Then, the solvent 35 is dehydrated (deliquored), and the resultant mixture is dried, whereby a preform is obtained. The kind of the fixing agent used herein is not particularly limited. The dehydration (dewatering) of the solvent 35 may be performed by a known method such as natural dehydration or squeezing by its own weight.

Next, the obtained preform is press-formed by a mold (hereinafter, also referred to as a "forming mold" or "press-forming mold") heated and held at a temperature equal to or higher than the curing temperature of the thermosetting resin, thereby obtaining a holder. Fig. 6A and 6B are process explanatory views showing a press molding process for molding the retainer.

The press forming die 51 shown in fig. 6A includes a cylindrical inner diameter side die 53, a cylindrical outer diameter side die 55, a base die 57, and a movable die 59. The movable die 59 has an annular protruding portion 59a. The inner diameter side mold 53 and the outer diameter side mold 55 are concentrically arranged with the center axis Ax as the center in a state where one side surface is in contact with the base mold 57. The inner diameter side mold 53 and the outer diameter side mold 55 are fixed to the base mold 57 by fasteners such as bolts. A cylindrical gap portion 61 is formed between the outer peripheral surface of the inner diameter side die 53 and the inner peripheral surface of the outer diameter side die 55. The preform 63 is provided in the gap portion 61 of the press mold.

In the press forming die 51 having the above-described structure, the outer peripheral surface of the inner diameter side die 53 that defines the gap portion 61 forms the inner diameter surface of the holder, and the inner peripheral surface of the outer diameter side die 55 forms the outer diameter surface of the holder. In the step of forming before the preform 63 is placed in the press mold 51, the preform is formed into a circular ring shape and placed in the gap portion 61 of the circular ring-shaped space larger than the circular ring shape.

In the molding step, the die is preferably preheated by a heater or the like, not shown, provided in the press molding die 51. This makes it possible to easily bring the thermosetting resin 33 contained in the preform 63 into a flowable state during the subsequent heat curing process. Then, in the pressing step based on the movement (pressing) of the movable die 59 shown in fig. 6B, the inner diameter surface and the outer diameter surface of the preform 63 are restrained and pressed in the axial direction of the annular shape (the direction of the central axis Ax) while being compressed.

More specifically, the inner diameter surface of the preform 63 is restrained by the outer peripheral surface of the inner diameter side mold 53, the outer diameter surface of the preform 63 is restrained by the inner peripheral surface of the outer diameter side mold 55, and the movable mold 59 having the annular protruding portion 59a fitted in the gap portion 61 is moved toward the base mold 57. Thereby, the preform 63 is compressed in the direction of the central axis Ax.

The constraints here refer to: the preform 63 is placed in light contact with the mold or with a gap between the molds before compression molding, but is compressed by gradually bringing the preform into close contact with the compression of the movable mold 59. In this step, the thermosetting resin 33 of the preform 63 placed in the mold may be in a flowable state, and there is no limitation on whether or not the preform 63 is heated and melted before being molded.

After the preform 63 is compression molded by pressing the movable mold 59 against the base mold 57, the preform 63 is heated in the press molding mold 51, and the thermosetting resin 33 contained in the preform 63 is thermally cured. The heating of the preform 63 at this time is a process of heating the press forming die 51 to a temperature equal to or higher than the thermosetting start temperature of the thermosetting resin 33. The thermosetting conditions of the thermosetting resin 33 may be appropriately set according to the type of resin or the like of the preform 63 to be used. The press-forming die 51 may be heated while the preform 63 is being compression-formed, and press-forming and heat-curing may be performed simultaneously. In this case, the tact time can be shortened. The compression-molded body 65 is obtained by the compression molding and the heat treatment described above.

The heat curing treatment may be used as a post-curing step for the purpose of suppressing dimensional shrinkage of the retainer in actual use and improving mechanical properties. In general, by adding a post-curing step, the fatigue properties, tensile strength, and chemical resistance of the molded article are improved. The thermosetting treatment may include a step of disposing the preform 63 in a cavity of a mold, and injecting a liquid resin into the cavity to mold the resin.

The compression molded body 65 after the press molding and the heat curing treatment may be in the shape of a holder, or the compression molded body 65 may be further machined to be finished into the shape of a holder. For example, the pockets 19a, 29a (fig. 2, 4) and the like of the retainers 19, 29 can be formed by post-processing. The pocket in this case may be formed by any method such as machining, laser machining, or water cutting. Further, a slide core or the like may be provided in the press molding die 51, and a pocket may be formed simultaneously with press molding.

The rolling bearings 11 and 21 shown in fig. 1 and 3 are assembled and manufactured using the cage manufactured as described above.

According to the present embodiment, in a rolling bearing used in a high-speed rotating environment such as a spindle of a machine tool, a preform manufactured by a papermaking (paper making) process is subjected to press forming and thermosetting treatment, instead of a conventional fiber-reinforced resin material, to obtain a cage. According to the method for manufacturing the cage, the cage with high strength and high rigidity can be obtained, and the rolling bearing with high reliability and long service life can be obtained while suppressing the damage of the cage.

Next, a modified example of the press molding step will be described.

Fig. 7A and 7B are process explanatory views showing other press forming processes for forming the retainer.

The press mold 71 shown in fig. 7A is similar to the press mold 51 described above, except that the outer diameter side mold 73 is divided into a plurality of blocks 73a along the circumferential direction of the inner diameter side mold 53, and each block 73a is changed to a slide core structure movable in the radial direction around the central axis Ax. Each block 73a moves radially in a plan view as viewed from the center axis Ax direction.

In the press forming die 71 of the present configuration, a preform 63 is provided in a cylindrical gap portion 61 between the outer peripheral surface of the inner diameter side die 53 and the inner peripheral surface of the outer diameter side die 73. Then, the movable mold 59 is moved toward the base mold 57 by a driving mechanism, not shown, to fix the side surface of the preform 63. As shown in fig. 7B, the plurality of blocks 73a are moved radially inward by a driving mechanism, not shown, and the preform 63 is press-formed from the radially outward side toward the inward side. The press forming in this case is mainly performed by the radial movement of the plurality of blocks 73a, but may be performed in cooperation with the pressing of the movable die 59.

In the case of the present structure, it is also preferable to preheat the press mold 71 in advance. The plurality of blocks 73a are pressed radially inward, the preform 63 is compression molded, and then the preform 63 is heated in the press mold 71 to thermally cure the thermosetting resin 33 contained in the preform 63. Thus, the compressed molded body 65 is obtained in the same manner as in the case described above.

According to the steps shown in fig. 7A and 7B, since the plurality of blocks 73a are moved in the radial direction, pockets in which rolling elements are disposed can be easily formed by pressing (see fig. 2 and 4). This reduces the number of processing steps, and enables efficient manufacturing of the retainer.

Second structural example

Next, a case where the composite molded article is a gear case component will be described. The gear case component is described as one component of a gear case used in the electric power steering apparatus, but the gear case component is not limited to this, and may be used in other apparatuses.

< Structure of electric Power steering device >

The electric power steering apparatus 100 transmits the assist output of the electric motor 111 to a steering mechanism 115 of the vehicle via a reduction gear mechanism 113. The electric power steering apparatus 100 illustrated in the drawings is an example, and may be another kind of mechanism.

In the electric power steering apparatus 100 shown in fig. 8, a steering shaft 117, which fixes a steering wheel, not shown, to an upper end portion thereof, is rotatably supported inside a steering shaft housing 119. The steering shaft housing 119 is fixed at a predetermined position inside the vehicle cabin in a state where a lower portion thereof is inclined toward the front of the vehicle.

The rack-and-pinion mechanism 121 that converts rotation of the steering shaft 117 into movement of the left and right steering wheels includes: a rack 123 that is movable in the axial direction, a pinion shaft 125, and a tubular rack housing 127 that supports the rack 123 and the pinion shaft 125. The pinion shaft 125 has a pinion gear supported in an oblique direction with respect to the axis of the rack 123 and provided with gear teeth meshing with the gear teeth of the rack 123.

The rack and pinion mechanism 121 is disposed substantially horizontally in the engine compartment in the front portion of the vehicle so that the longitudinal direction thereof extends in the width direction of the vehicle. The upper end portion of the pinion shaft 125 and the lower end portion of the steering shaft 117 are coupled by two universal joints 129 and 131. A steering wheel, not shown, is coupled to both end portions of the rack 123.

When the driver applies steering torque (rotational force) to the steering wheel, the steering shaft 117 rotates, and the steering torque is detected by a torque sensor (not shown) attached to the steering shaft 117. Then, the output of the electric motor 111 (the rotational force of the assist steering) is controlled based on the detected steering torque. The output of the electric motor 111 is supplied to the intermediate portion of the steering shaft 117 via the reduction gear mechanism 113, and is converted into a motion for steering the steered wheels by the rack-and-pinion mechanism 121 in accordance with the steering torque.

Fig. 9 is a partial sectional view of the line IX-IX shown in fig. 8, and fig. 10 is a partial sectional view of the line X-X shown in fig. 9.

As shown in fig. 9 and 10, a gear case 133 accommodating the reduction gear mechanism 113 of the electric power steering apparatus 100 mounted on a vehicle body (not shown) includes: a gear case main body 135 having a bottomed cylindrical shape shown in fig. 10 and a gear case cover 137 are used as gear case constituent members. The gear case cover 137 closes the opening of the gear case body 135 and is fixed to the gear case body 135. That is, the bolts 139 are inserted through openings provided on the gear box cover 137 side and fastened to screw holes provided on the gear box main body 135 side. Thus, the gear case 133 is obtained in which the gear case main body 135 and the gear case cover 137 are fastened together by the bolts 139.

Inside the gear case 133, the intermediate steering shaft 148 is rotatably supported by a first rolling bearing 151 and a second rolling bearing 153. In addition, a reduction gear mechanism 113 is housed inside the gear case 133, and a torque sensor 159 as a steering state detection sensor is housed.

The reduction gear mechanism 113 is constituted by a worm wheel 155 and a worm shaft 157 shown in fig. 9. The worm wheel 155 is fixed to an axially intermediate portion of the intermediate steering shaft 148 shown in fig. 10. The worm shaft 157 shown in fig. 9 is coupled to the rotation shaft 161 of the electric motor 111 via a spline joint 163, and is engaged with the worm wheel 155.

As shown in fig. 10, the worm wheel 155 includes: a disk portion 155a that is integrally rotatably fixed to the intermediate steering shaft 148; and synthetic resin teeth 155b formed on an outer diameter portion of the circular plate portion 155 a. The intermediate steering shaft 148 is rotatably supported by first and second rolling bearings 151 and 153 disposed on both axial sides of a worm wheel 155.

The torsion bar 167 is disposed through the shaft centers of the steering shaft 117 and the intermediate steering shaft 148, and the left end portion is integrally fixed to the intermediate steering shaft 148 by a connecting pin 169 in the figure, and the right end portion is press-fitted into the steering shaft 117 in the figure to be fixed.

Accordingly, the rotational force (steering torque) of the steering shaft 117 is transmitted to the intermediate steering shaft 148 via the torsion bar 167.

As shown in fig. 9, the worm shaft 157 engaged with the worm wheel 155 is rotatably supported by the third rolling bearing 175 and the fourth rolling bearing 177 held by the gear housing 173. The base end side end of the worm shaft 157 is coupled to the rotation shaft 161 of the electric motor 111 via a spline joint 163.

< Gear case component >

Next, the gear case 133 will be described in detail.

(Structure of gearbox)

As shown in fig. 10, the gear case 133 is constituted by a plurality of gear case constituent members including a gear case main body 135 and a gear case cover 137. The gear case main body 135 and the gear case cover 137 are each configured to mainly have a resin composition in which reinforcing fibers (fibrous filler) of long fibers are dispersed in a resin material. The reinforcing fibers are contained in the resin material in a predetermined ratio according to the purpose of use. This improves impact resistance, creep property, rigidity, and dimensional stability, as compared with the case where the gear case 133 is molded from a resin material alone.

The gear case 133 illustrated in the drawing is composed of two members, i.e., a gear case main body 135 and a gear case cover 137, but is not limited thereto, and other members may be further combined. In this case, the other member may be a resin material containing the fibrous filler of the long fibers.

The gear case body 135 made of resin including reinforcing fibers and the gear case cover 137 are fastened to each other by bolts 139, and thereby the gear case 133 is integrally formed. The fastening portion of the gear case main body 135 and the gear case cover 137 by the bolts 139 may be configured such that the embedded core wires 143, 147 are connected to each other by insert-molding the core wire 143 on the side of the gear case main body 135 made of metal and the core wire 147 on the side of the gear case cover 137 made of metal. The gear case main body 135 may be configured to include a core metal 145 for fixing the first rolling bearing 151, and the gear case cover 137 may be configured to include a core metal 149 for fixing the second rolling bearing 153. The gear case 133 of this structure is constituted by having a resin component, and therefore, the entire gear case is lighter than in the case of a conventional product made of metal, and has durability and reliability equivalent to those of the conventional product.

In addition, although not shown, it is preferable to provide an O-ring groove and an O-ring fitted in the O-ring groove on the joint surface where the gear case main body 135 and the gear case cover 137 are fastened by bolts, so as to prevent leakage of grease sealed in the gear case 133.

The gear case body 135 and the gear case cover 137 in the case of having the core metal have the structure shown in fig. 11A and 11B.

Fig. 11A is a top view showing the gear case main body 135 with core gold in a single body, and fig. 11B is a top view showing the gear case cover 137 with core gold in a single body.

In the gear case main body 135 shown in fig. 11A, a core metal 143 as a fastening portion with the gear case cover 137 and a core metal 144 fitted with the first rolling bearing 151 are provided integrally with the resin component 141. In the gear case cover 137 shown in fig. 11B, a core metal 145 as a fastening portion with the gear case main body 135 and a core metal 146 fitted with the second rolling bearing 153 are provided integrally with the resin composition 142. These core wires 143, 144, 145, 146 are integrally molded with the resin components 141, 142 as embedding materials.

The gear case main body 135 and the gear case cover 137 (hereinafter, also referred to as gear case constituent members) having the above-described structure are manufactured substantially as follows.

First, a reinforcing fiber having an average fiber length of 0.5mm or more is opened in a solvent. As the solvent, for example, water can be used. The fiber-containing slurry is obtained by dispersing and mixing the reinforcing fibers and the resin (in powder form and fiber form) in the solvent. The fiber-containing slurry is dehydrated by a sheet or a papermaking die to remove water (dry), thereby forming a preform. Here, a plurality of types of preforms (described in detail later) in which the bulk densities of the reinforcing fibers are different are prepared. The preform formed herein is a reference density preform, and the reference density preform is further compression molded to obtain a high density preform. The formed preform having the bulk densities is set in a molding die, and when the resin dispersed and mixed in the preform is a thermosetting resin, the preform is heat-cured. The temperature at which the thermosetting resin is heated is not particularly limited, and may be appropriately selected within a temperature range in which impregnation and melting of the resin serving as a base material are sufficiently performed and deterioration does not occur. Thus, a gear box component based on the fiber reinforced resin composition was obtained.

(constituent Material of Gear case constituent Member)

As a constituent material of the gear case constituent member, for example, a material obtained by mixing reinforcing fibers such as glass fibers and carbon fibers as fibrous fillers with thermosetting resins such as epoxy resins and phenolic resins as resin materials is preferable. In addition, a part of the thermosetting resin may be replaced with a thermoplastic resin. By using a thermosetting resin as a constituent material, a structure excellent in heat resistance and mechanical strength can be formed.

In addition, in view of durability and reliability as a molded article, a fiber-reinforced resin composition comprising a thermosetting resin as a base resin and reinforcing fibers filled in the base resin is preferably used.

By using the fiber-reinforced resin composition, the impact resistance of the gear box component can be sufficiently ensured.

The reinforcing fiber is not particularly limited, and examples thereof include glass fiber, carbon fiber, metal fiber, aramid fiber, aromatic polyimide fiber, liquid crystal polyester fiber, silicon carbide fiber, alumina fiber, boron fiber, cellulose nanofiber, and the like.

In particular, glass fibers and boron fibers are preferable because they have high tensile strength. The carbon fiber is excellent in abrasion resistance, heat resistance, thermal stretchability, acid resistance, and electrical conductivity. As the metal fiber, a metal wire of stainless steel, aluminum, iron, nickel, copper, or the like can be used. The aramid fiber has high tensile strength, high frictional resistance, and excellent high temperature and chemical resistance. The aromatic polyamide fiber has very excellent heat resistance and strength. The liquid crystal polyester fiber has rigidity exceeding that of the engineering plastic reinforced by the filler even in a non-reinforced state. Alumina fibers can be used in a high temperature range and have fire resistance.

The fiber length of the reinforcing fiber is preferably 0.5mm or more, more preferably 0.7mm or more, and even more preferably 1mm or more. When a fiber having an average fiber length of 0.5mm or more is added, the impact resistance and dimensional stability are improved more than when a fiber having an average fiber length of less than 0.5mm is added. Therefore, the reinforcing effect of the resin material in the composite material can be reliably obtained by setting the average fiber length to 0.5mm or more.

The blending amount of the reinforcing fibers in the fiber-reinforced resin composition is preferably 10 to 60 mass%. By setting the amount of the reinforcing fibers to be 10 mass% or more in the fiber-reinforced resin composition, durability higher than that of the conventional products can be obtained. In addition, the blending amount of the reinforcing fiber is 60 mass% or less, whereby the toughness of the material is not impaired, for example, the thermal shock resistance is not insufficient.

The fiber-reinforced resin composition can improve the affinity between the resin material and the reinforcing fiber by treating the reinforcing fiber with a coupling agent such as a silane coupling agent or a titanate coupling agent. This can improve the adhesion between the resin material and the reinforcing fibers and the dispersibility. The coupling agent is not limited to a silane coupling agent and a titanate coupling agent.

Further, various additives may be blended into the fiber-reinforced resin composition within a range that does not impair the object of the present invention. Examples of the additives include solid lubricants such as graphite, hexagonal boron nitride, fluoromica, tetrafluoroethylene resin powder, tungsten disulfide, and molybdenum disulfide, inorganic powders, organic powders, lubricating oils, plasticizers, rubbers, antioxidants, heat stabilizers, ultraviolet absorbers, photo-protecting agents, flame retardants, antistatic agents, mold release agents, fluidity improving materials, thermal conductivity improving agents, non-tackiness imparting agents, crystallization accelerators, nucleating agents, pigments, and dyes.

(specific step of Forming the Gear case component parts)

When the above-described resin material, reinforcing fibers, and various additives are mixed to manufacture a gear box component, a plurality of preforms having reinforcing fibers with an average fiber length of 0.5mm or more and different bulk densities are integrally molded with the resin material and the insert material by press molding.

As the preform, a reference density preform formed with a bulk density as a reference and a preform formed with a bulk density higher than the reference are usedBulk density of density a high density preform is formed. The reinforcing fibers having an average fiber length of 0.5mm or more and a bulk density (first bulk density) of 0.4g/cm ³ Above, 1.0g/cm ³ Hereinafter, the minimum strength required after resin molding is set. The high-density preform is set to a bulk density higher than the first bulk density, and for example, it is preferable that the density of the molded article (resin composition excluding the metal portion) is 50% to 80%.

The reference density preform described above can be easily processed into various shapes, and thus can be formed into a free shape corresponding to the shape of the molded article. The high-density preform can be molded by compressing the reference-density preform that has been formed, and the strength can be improved. In the reference density preform and the high density preform, the resin is dispersed and mixed among the reinforcing fibers. That is, since the reinforcing fibers and the resin are mixed in the single body of the preform, the resin is surely impregnated into the entire inside of the reference density preform and the high density preform in the resin molding in the subsequent step.

The high density preform is preferably selectively placed in the gearbox component where high strength is desired. In this way, the reinforcing fiber is highly dense at the portions where high strength is required, and is relatively dense at other portions, so that the strength of the molded article can be locally adjusted. As a result, the required strength can be accurately set for each part of the molded article, and the amount of the reinforcing fibers to be blended can be suppressed particularly in the part where the strength is not required. In addition, the weight of the gear case constituent members can be reduced, and the gear case constituent members can be configured to have durability and reliability equivalent to those of conventional metallic products. In addition, since the reinforcing fiber is not wastefully used, an economically excellent structure can be realized.

In addition, the resin components 141 and 142 near the boundaries with the core metals 143, 144, 145 and 146 are likely to be subjected to stress greater than other parts by external force. Accordingly, the high-density preform may be arranged in the region including the boundary with the core metals 143, 144, 145, 146 in the resin components 141, 142, and the reference-density preform may be arranged in the other region.

Fig. 12A and 12B are structural diagrams of a molded article 80 simulating a gear case cover, fig. 12A is an axial cross-sectional view, and fig. 12B is a plan view.

The molded article 80 has a shaft portion 80a and a flange portion 80b, and a large stress is generated in the shaft portion 80 a. In this case, a high-density preform is disposed at a portion of the molding die which becomes the shaft portion 80a, a reference-density preform is disposed at a portion which becomes the flange portion 80b, and resin is supplied into the cavity of the molding die to mold the preform. The resin to be supplied into the cavity is preferably the same as the resin dispersed and mixed in the reference density preform and the high density preform, but other resins may be substituted or appropriate additives may be mixed.

The high-density preform and the reference-density preform may be disposed in the cavity, respectively, but by integrating the high-density preform and the reference-density preform in advance, the molding process can be simplified.

Fig. 13A, 13B, and 13C are process explanatory views showing the processing process of the integrated preform.

As shown in fig. 13A, a high-density preform 85 is disposed at a portion corresponding to the shaft portion 80a (fig. 12A and 12B) inside the fixed-side mold 83, and a reference-density preform 87 is disposed at a portion corresponding to the flange portion 80B. Then, as shown in fig. 13B, the movable mold 89 is moved toward the fixed mold 83, and both are integrally press-molded into a shape close to a molded article. In this case, resin may be additionally placed in each preform to be placed, so that the impregnated state of the resin may be more uniform. Thus, as shown in fig. 13C, an integrated preform 90 is obtained in which the high-density preform 85 and the reference-density preform 87 are integrated in the mold.

Next, the obtained integrated preform 90 is opened and the fixed side mold 83 and the movable side mold 89 are taken out. Then, the removed integrated preform 90 is placed in a cavity of a resin molding die, not shown, and resin molding is performed. Thereby, the molded article 80 shown in fig. 12A and 12B is molded. This allows the high-density preform 85 and the reference-density preform 87 to be handled integrally, which improves the operability and the workability of the molding process.

The integrated preform 90 may be molded by directly supplying resin to the cavity in the mold without being taken out from the fixed side mold 83 and the movable side mold 89. That is, the mold for forming the integrated preform 90 may be directly used as a mold for resin molding, thereby simplifying the molding process.

The above-described method for manufacturing the gear case constituent member constituting the gear case accommodating the gear mechanism includes the following steps.

(1) Preparing a reference preform formed of reinforcing fibers having an average fiber length of 0.5mm or more at a first bulk density, and a preform formed of reinforcing fibers at a specific first bulk density (e.g., 0.4g/cm ³ Above and 1.0g/cm ³ The following) a high density preform formed at a high second bulk density.

(2) And disposing the reference preform and the high-density preform in the cavity of the molding die.

(3) And filling the cavity with a resin, and performing resin molding together with the reference preform and the high-density preform.

The gear box component of the structure comprises a part provided with the high-density preform and a part provided with the reference preform, wherein the part provided with the high-density preform has higher density of reinforcing fibers than other parts, and can improve the impact resistance, creep property and rigidity of the formed product. Further, the weight can be reduced as compared with conventional metallic gear case components. When molding is performed using only the preform of the reference density, the reinforcing fibers flow during molding, causing turbulence in the orientation direction, and easily causing a decrease in strength. On the other hand, when molding is performed using a high-density preform, the flow of reinforcing fibers does not occur during molding, and therefore the strength of the molded article increases, but reinforcing fibers may not be filled at the end of the product. Therefore, by combining the high-density preform and the reference-density preform, the strength of the molded article is maintained by the high-density preform, and the reinforcing fibers are filled into the end of the molded article by the reference-density preform, whereby the reinforcing fibers are dispersed throughout the molded article.

In addition, by joining the high-density preform and the insert material to each other and disposing the preform in the cavity, the strength of the region including the boundary with the insert material can be selectively increased. When a large external force is applied to the portion of the insert material, the molded article can have an excellent structure with high strength.

In the case of the gear case main body 135 and the gear case cover 137 shown in fig. 11A and 11B, they are manufactured by insert molding of a resin material with core wires 143 and 145 of the fastening portion and core wires 144 and 146 fitted to the first rolling bearing 151 and the second rolling bearing 153 as cores. Thus, the dimensional stability of the molded article becomes good. In addition, the fixing strength of both the gear case main body 135 and the gear case cover 137 is improved. Further, since the gear case main body 135 and the gear case cover 137 can be fastened by bolts as in the case of the metal, durability and reliability equivalent to those of the conventional products can be obtained while achieving weight reduction.

In the case where the thermosetting resin material is used as the resin material in the gear case main body 135 and the gear case cover 137 of the present structure, the inner and outer rings of the rolling bearing and the core metal made of metal can be bonded to each other with sufficient reliability. In order to further secure high-reliability adhesive strength, it is preferable to apply an adhesive to the surface of the core metal, the surface of the rail wheel, or the joint surface. In this case, a desired strong adhesion state can be obtained.

According to the above method, a high-strength gear box constituent member formed by including reinforcing fibers having an average fiber length of 0.5mm or more in a resin material at a bulk density corresponding to a required strength, in addition to a metal core metal portion, can be obtained.

In the above-described production method, after a preform, which is impregnated with a resin to a certain extent in advance, is placed in a cavity of a mold, a resin molding step is performed in which molten resin is injected into the cavity and pressurized. According to this method, a surface layer including a resin encapsulating reinforcing fibers and having a smooth surface is formed on the surface of the molded article. By forming the surface layer, the mechanical strength of the molded article is improved and the dimensional stability is improved. The above-described manufacturing method can be suitably used for manufacturing a retainer, for example, and can easily form a guide surface having high strength and high dimensional accuracy.

Here, a method for manufacturing a retainer using a high-density preform and a reference-density preform will be described.

For example, taking the retainer 19 shown in fig. 2 as an example, it is preferable to apply a high-density preform to the annular portion 19A of the retainer 19 and a reference-density preform to the column portion 19B. The specific manufacturing process in this case includes the following steps.

First, a high-density preform having a circular ring shape corresponding to the circular ring portion 19A and a reference density preform having a column shape corresponding to the column portion 19B are formed by the above-described forging according to the shape of the holder 19. The obtained high-density preform is placed at the position of the molded annular portion 19A in the cavity of the molding die, and the reference-density preform is placed at the position of the molded pillar portion 19B in the cavity. Then, the molding die is closed, heated, and then the molten resin is injected into the cavity. After the molten resin in the cavity is solidified, the mold is opened, whereby a holder for a composite molded article is obtained in which the annular portion 19A including the high-density preform and the pillar portion 19B including the reference-density preform are integrally impregnated with the resin. A surface layer is formed on the surface of the holder.

The retainer thus formed is suitable as an outer ring guide type or an inner ring guide type retainer because the annular portion 19A is formed with high strength and high accuracy. In addition, since the pillar portion 19B is flexible as compared with the annular portion 19A, it is easy to insert rolling elements (rollers) into the pockets.

The preform used herein may be a high-density preform and a low-density preform, respectively, but the high-density preform may be produced by temporarily forming the whole of the shape of the retainer with the low-density preform and selectively compressing the portion corresponding to the annular portion 19A. In this case, the portion corresponding to the annular portion 19A may be formed of a large-sized low-density preform to which a compression amount is added, and may be compressed to a desired size.

The composite molded article is not limited to the holder, and may be molded in the same manner as described above as long as it is cylindrical or annular. In addition, in the case of a molded article having an inner peripheral surface formed of a cylindrical surface, a member having an outer peripheral surface of a corresponding shape can be easily fitted to the inner peripheral surface of the molded article. For example, a hole portion into which the outer circumferential surface of the outer ring of the rolling bearing is fitted can be formed in the housing with high strength and high accuracy.

Examples (example)

The results of evaluating the strength of the composite molded article will be described below by taking the molded article 80, which mimics the shape of the gear box cover shown in fig. 12A and 12B, as an example. However, the present invention is not limited to the shape shown in fig. 12A and 12B.

Test example 1

A high-density preform having a shape corresponding to the shaft portion 80a and a reference preform having a shape corresponding to a portion other than the cylindrical portion are produced, respectively, the shaft portion 80a including a reinforcing fiber having a bulk density of 1.1g/cm ³ The material obtained by mixing and kneading the materials was calculated in such a manner that the volume density of the reinforcing fibers was 0.6g/cm in the portions other than the cylindrical portion ³ The method of (a) is to calculate the material to be blended and made, set these preforms in the cavity of a molding die, and then, inject the molten resin material into the cavity, and press-mold the molten resin material together with the preforms to produce molded articles.

Test example 2

The preparation comprises a bulk density of 0.6g/cm of reinforcing fibers ³ A reference preform having a shape corresponding to the molded article and obtained by mixing and kneading the materials is set in a cavity of a molding die, and then a molten resin material is injected into the cavity to be press-molded together with the preform. Thus, a molded article was produced.

In test examples 1 and 2, carbon fibers having an average fiber length of 5.0mm were used as reinforcing fibers, and phenol resins were used as resin materials. The high-density preform was formed by winding a reference density preform around a rod body and compressing the reference density preform radially toward the rod body using 2 split dies that divide the cylindrical shape into two. The temperature at the time of compression is adjusted not to exceed the curing temperature of the resin. Then, the resin is cured by heating.

From the molded articles of test examples 1 and 2, test pieces were cut out from each portion of the flat surface portion 91 including the upper surface of the flange portion 80B, the side surface portion 93 including the side surface of the flange portion 80B, and the cylindrical portion 95 including the side surface of the shaft portion 80a shown in fig. 14A and 14B, and bending tests of each test piece were performed. The test results are shown in Table 1. The bending test is a test method according to ISO 178 (JISK 7171).

TABLE 1

As shown in table 1, in test example 2, the bending strength of the cylindrical portion 95 is lower than the bending strength of the flat portion 91 and the side portion 93. On the other hand, test example 1 was a result of obtaining substantially the same high bending strength in all the portions of the flat surface portion 91, the side surface portion 93, and the cylindrical portion 95. That is, it is known that the bending strength of the reference density preform of test example 2 is lowered by the portion of the molded article, but in the case of using the high density preform of test example 1, high strength can be stably obtained regardless of the portion of the molded article.

As described above, the following matters are disclosed in the present specification.

(A1) A method for manufacturing a cage for use in a rolling bearing includes:

preparing a solution by dispersing and mixing reinforcing fibers having an average fiber length of 0.5mm or more and a thermosetting resin in a solvent;

forming a preform by removing the solvent from the dispersion-mixed solution by papermaking; and

and a step of press-forming the obtained preform by using a die set at a temperature equal to or higher than the curing temperature of the thermosetting resin to form the retainer.

According to this method for manufacturing a retainer, the retainer is formed by press forming a preform formed by forging, and therefore, even when used in a high-speed rotating environment, a good lubrication state can be maintained, reliability is high, and a long life can be realized.

(A2) The method for manufacturing a holder according to (A1), wherein,

the reinforcing fiber is at least one selected from carbon fiber, aramid fiber, glass fiber, cellulose fiber, polyarylate fiber, and poly-p-phenylene benzobisoxazole fiber.

According to the method for manufacturing the retainer, the reinforcing property of the reinforcing fiber can be ensured.

(A3) The method for producing a retainer according to (A1) or (A2), wherein,

the amount of the reinforcing fiber to be mixed in the solution is 10 to 60 mass%.

According to the method for manufacturing the retainer, mechanical strength can be remarkably improved, toughness of the material is not impaired, and target strength and rigidity can be ensured.

(A4) The method for manufacturing a retainer according to any one of (A1) to (A3), wherein,

the thermosetting resin is at least one selected from epoxy resin, bismaleimide resin, polyaminoamide resin, polyimide resin and phenolic resin.

According to this method for manufacturing a retainer, the retainer can be easily cured by a heat curing process.

(A5) The method for producing a cage according to (A4), wherein the thermosetting resin is in the form of powder.

According to the method for manufacturing the retainer, the reinforcing fibers and the thermosetting resin can be sufficiently dispersed and mixed in the papermaking process.

(A6) The method for manufacturing a retainer according to any one of (A1) to (A5), wherein,

the press forming is compression forming from the radially outer side of the retainer.

According to this method for manufacturing the retainer, the preform can be press-formed from the radially outer side toward the radially inner side.

(A7) A method of manufacturing a rolling bearing, comprising using the cage manufactured by the method of manufacturing a cage according to any one of (A1) to (A6).

According to this method for manufacturing a rolling bearing, even when used in a high-speed rotating environment, reliability can be improved while maintaining a good lubrication state, and a long life can be realized.

(B1) A manufacturing method of a gear case constituent member that constitutes a gear case accommodating a gear mechanism, comprising:

a step of preparing a reference preform formed of reinforcing fibers having an average fiber length of 0.5mm or more and having a first bulk density and a high-density preform formed of the reinforcing fibers and having a second bulk density higher than the first bulk density;

Disposing the reference preform and the high-density preform in a cavity of a molding die; and

and filling the cavity with a resin, and performing resin molding together with the reference preform and the high-density preform.

According to the method of manufacturing the gear case constituent member, the gear case constituent member having the portion provided with the high-density preform and the portion provided with the reference preform is formed.

By this, the arrangement of the high-density preform can increase the density of the reinforcing fibers in a portion where high strength is particularly required as compared with other portions. Therefore, characteristics excellent in impact resistance, creep characteristics, rigidity, and dimensional stability can be obtained, and weight reduction can be achieved as compared with the case of a metal.

(B2) The method for manufacturing a gear box constituent member according to (B1), wherein,

the first volume density is 0.4g/cm ³ Above and 1.0g/cm ³ The following is given.

According to the manufacturing method of the gear case component, the necessary minimum strength can be maintained.

(B3) The method for manufacturing a gear box constituent member according to (B1) or (B2), wherein,

in the reference preform and the high-density preform, the resin is mixed between the reinforcing fibers.

According to the method for manufacturing the gear case component, the resin is mixed in advance in the reference preform and the high-density preform, so that the resin can be impregnated into the preform reliably.

(B4) The method for manufacturing a gear box constituent member according to any one of (B1) to (B3), wherein,

the method includes a step of press-forming the reference preform integrally with the high-density preform before filling the resin into the molding die.

According to the method for manufacturing the gear box constituent member, since the reference preform and the high-density preform are integrated, the preforms are joined to each other without any gap, and the reinforcing fibers can be uniformly distributed. In addition, in the case of processing the preform as one body, the operability of the preform can be improved, and the operability of the forming process can be improved. In addition, the reference preform is easily processed into various shapes at the time of press molding, and thus gear boxes of various shapes can be manufactured.

(B5) The method for manufacturing a gear box constituent member according to any one of (B1) to (B4), wherein,

the reinforcing fibers comprise at least one of carbon fibers, glass fibers, aramid fibers.

According to the method for manufacturing the gear case component, the gear case component can be made lightweight and high-strength.

(B6) The method for manufacturing a gear box constituent member according to any one of (B1) to (B5), wherein,

the resin is any one of epoxy resin and phenolic resin.

According to the method for manufacturing the gear case component, the gear case component can be made to have excellent creep characteristics such as heat resistance, bending, and warping.

(B7) The method for manufacturing a gear box constituent member according to any one of (B1) to (B6), wherein,

by the resin molding, a thermoplastic resin composition containing 10 to 60 mass% of the reinforcing fiber is formed.

According to the gear case component, impact resistance, creep property, rigidity, and dimensional stability can be improved as compared with a resin single body.

(B8) The method for manufacturing a gear box constituent member according to any one of (B1) to (B7), wherein,

in the step of disposing the high-density preform in the cavity, the high-density preform is disposed so as to be bonded to a metal insert material.

According to the method for manufacturing the gear case constituent member, the high-density preform is provided in contact with the insert material, so that the density of the reinforcing fibers around the insert material is selectively increased, and the strength after molding is improved.

(B9) The method for manufacturing a gear box constituent member according to any one of (B1) to (B8), wherein,

the gear case component is a component of an electric power steering apparatus that transmits an auxiliary output of an electric motor to a steering mechanism of a vehicle via a reduction gear mechanism, and is configured to accommodate the reduction gear mechanism.

According to the method for manufacturing the gear box component, the gear box of the electric power steering device which is light in weight and has the same durability and reliability as the case of metal can be obtained.

The present invention is not limited to the above-described embodiments, and modifications and applications of the present invention by those skilled in the art based on the description of the specification and known techniques are intended to be included in the scope of the present invention. For example, the present invention can be applied to a gear device or the like as a composite molded product.

Further, the present application is based on Japanese patent applications (Japanese patent application No. 2021-082611) filed on 5 months and 14 days of 2021, and Japanese patent application No. 2022-071024 filed on 4 months of 2022, the contents of which are incorporated herein by reference.

Claims

1. A method for producing a composite molded article, comprising:

2. The method for producing a composite molded article according to claim 1, wherein,

the method includes a step of filling a cavity of the molding die with a resin to mold the preform.

3. The method for producing a composite molded article according to claim 2, comprising:

a step of preparing a reference preform formed of the reinforcing fibers at a first volume density and a high-density preform formed of the reinforcing fibers at a second volume density higher than the first volume density as the preforms;

disposing the reference preform and the high-density preform in a cavity of the molding die; and

4. The method for producing a composite molded article according to claim 3, wherein,

5. The method for producing a composite molded article according to claim 3, wherein,

in the reference preform and the high-density preform, the thermosetting resin is mixed between the reinforcing fibers.

6. The method for producing a composite molded article according to claim 3, wherein,

comprises a step of press-forming the reference preform integrally with the high-density preform before filling the resin into the forming mold.

7. The method for producing a composite molded article according to claim 3, wherein,

8. The method for producing a composite molded article according to any one of claim 1 to 7, wherein,

the composite material molded article is cylindrical or annular.

9. The method for producing a composite molded article according to any one of claim 1 to 7, wherein,

10. The method for producing a composite molded article according to any one of claim 1 to 7, wherein,

in the step of molding the composite molded article, a thermoplastic resin containing 10 mass% to 60 mass% of the reinforcing fiber is formed.

11. The method for producing a composite molded article according to any one of claim 1 to 7, wherein,

12. The method for producing a composite molded article according to any one of claim 1 to 7, wherein,

the thermosetting resin is in a powder form.

13. The method for producing a composite molded article according to any one of claim 1 to 7, wherein,

the press forming is performed by compression forming from the radially outer side of the composite material molded article in a cylindrical shape or a circular ring shape.

14. A manufacturing method of a retainer is characterized in that,

a cage for use in a rolling bearing is manufactured by the method for manufacturing a composite molded article according to any one of claims 1 to 7.

15. A method for manufacturing a rolling bearing, characterized in that,

a rolling bearing manufactured using the cage manufactured by the manufacturing method of the cage of claim 14.

16. A method for manufacturing a gear box component is characterized in that,

a gear case constituent member constituting a gear case accommodating a gear mechanism is manufactured by the method for manufacturing a composite material molded article according to any one of claims 1 to 7.

17. The method of manufacturing a gear box component according to claim 16, wherein,

18. A method for manufacturing a gear box component is characterized in that,

the gear case constituent member constitutes a gear case accommodating a gear mechanism, and the manufacturing method includes: