Gear manufacturing method, gear and flexible mesh gear device

Abstract

To provide a manufacturing method that enables manufacture of a gear with accuracy high enough to enable application to a gear device while having the advantage of a molded article formed from a fluid material, the gear, and the deflection meshing type gear device having the gear like this.SOLUTION: A method of manufacturing a gear includes: an intermediate product formation step (J1) of forming a gear intermediate product (IN) by solidifying a fluid material; and a tooth formation step (J2) of forming a tooth (23 g) in the gear intermediate product (IN) by cutting machining. The gear (23) has a fluid-solidified part that has an outer surface formed by solidifying the fluid material, and a cutting-machined part, the outer surface of which is cutting-machined. The tooth (23 g) is included in the cutting-machined part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a gear, a gear, and a flexible mesh gear device. [Background technology]

[0002] Patent Document 1 shows a gear made of a resin material containing carbon fibers. The gear in Patent Document 1 has carbon fibers with a length of 100 μm or less, ensuring durability and wear resistance even for a small gear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-155313 Summary of the Invention [Problem to be solved by the invention]

[0004] Forming gears by solidifying a fluid material (e.g., a resin material) offers various advantages, such as lower costs. However, molded products formed by solidifying a fluid material are prone to dimensional variations due to various factors that occur during molding. When gears formed by solidifying a fluid material are used in a gear device, the required precision may not be achieved.

[0005] An object of the present invention is to provide a gear and a manufacturing method that can produce a gear with precision suitable for use in a gear device while retaining the advantages of a molded product formed from a fluid material, and to provide a flexible mesh gear device having such a gear. [Means for solving the problem]

[0006] The method for manufacturing a gear according to the present invention comprises the steps of: A method for manufacturing an internal gear, comprising: Molten resin or aluminum an intermediate forming step of solidifying the fluid material to form a gear intermediate; a tooth forming step of forming teeth on the gear intermediate body by cutting; a cutting process for cutting at least one of a fitting surface of the gear intermediate body to which another member is spigot-fitted and a fitting surface to which a bearing is fixed; Includes:

[0007] The gear according to the present invention comprises: Molten resin or aluminum A gear having a fluid solidified portion whose outer shape is formed by solidifying a fluid material, and a machined portion which is machined, the gear is an internal gear, The machined portion includes teeth and at least one of a fitting surface to which another member is spigot-fitted and a fitting surface to which a bearing is fixed.

[0008] The flexible mesh gear device according to the present invention comprises: A flexible meshing gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, and an internal gear that meshes with the external gear, The internal gear is Molten resin or aluminum The molded article has a fluid solidified portion having an outer shape formed by solidifying a fluid material, and a machined portion, The machined portion includes teeth and at least one of a fitting surface to which another member is spigot-fitted and a fitting surface to which a bearing is fixed. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a gear with precision suitable for use in a gear device while retaining the advantages of a molded product formed from a fluid material, and further to provide a flexible mesh type gear device having such a gear. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a flexible mesh gear device according to an embodiment of the present invention; [Figure 2] 2A and 2B are diagrams showing a second internal gear according to an embodiment of the present invention, in which (A) is a plan view and (B) is a cross-sectional view taken along line AA. [Figure 3] 5A and 5B are diagrams illustrating the manufacturing process of the second internal gear, in which (A) shows the injection molding process, (B) shows the gear intermediate body released from the mold, and (C) shows the tooth cutting process. [Figure 4] FIG. 2 is a plan view showing a gear intermediate body. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] Fig. 1 is a cross-sectional view showing a flexible mesh gear device 1 according to this embodiment. Hereinafter, the direction along the rotation axis O1 in Fig. 1 will be referred to as the "axial direction," the direction perpendicular to the rotation axis O1 as the "radial direction," and the direction of rotation about the rotation axis O1 as the "circumferential direction." Furthermore, in the axial direction, the side of the second cover 27 from which the reduced rotational motion is output will be referred to as the "output side," and the opposite side will be referred to as the "anti-output side."

[0013] 1 is a cylindrical flexible mesh gear device in which an external gear 12 undergoes flexural deformation to transmit rotational motion about a rotation axis O1. The flexible mesh gear device 1 includes a vibration exciter shaft 10, an external gear 12 that is flexibly deformed by the vibration exciter shaft 10, a first internal gear 22 and a second internal gear 23 that mesh with the external gear 12, and a vibration exciter bearing 15. The flexible mesh gear device 1 also includes a casing 24, a first cover 26, a second cover 27, input bearings 31 and 32, and a main bearing 33.

[0014] The vibrator shaft 10 is hollow and includes a vibrator 10A having an elliptical cross section perpendicular to the rotation axis O1, and shaft portions 10B and 10C located on both sides of the vibrator 10A in the axial direction, each having a circular cross section perpendicular to the rotation axis O1. Note that the elliptical shape is not limited to a strict geometric ellipse, but also includes an approximate ellipse. The vibrator shaft 10 rotates around the rotation axis O1, and the center of the cross section of the vibrator 10A perpendicular to the rotation axis O1 coincides with the rotation axis O1. The vibrator shaft 10 is an input shaft that is connected to a drive source (not shown), such as a motor, to input driving force.

[0015] The external gear 12 is a cylindrical flexible metal member having teeth on its outer periphery.

[0016] The vibrator bearing 15 is disposed between the vibrator 10A and the external gear 12. The vibrator bearing 15 has a plurality of rolling elements (rollers) 15A and a cage 15C that holds the plurality of rolling elements 15A. The plurality of rolling elements 15A roll with the outer peripheral surface of the vibrator 10A and the inner peripheral surface of the external gear 12 as rolling surfaces (also called raceway surfaces). Note that the vibrator bearing 15 may have an inner ring separate from the vibrator 10A, an outer ring separate from the external gear 12, or both.

[0017] Spacer rings 36 and 37 are provided on both axial sides of the external gear 12 and the retainer 15C of the vibrator bearing 15, as restricting members that come into contact with them and restrict their axial movement.

[0018] The first internal gear 22 and the second internal gear 23 have teeth 22g and 23g on their inner peripheries, respectively. The teeth 22g and 23g are aligned in the axial direction, with one meshing with the teeth on one side of the axial center of the external gear 12, and the other meshing with the teeth on the other side of the axial center of the external gear 12.

[0019] The outer periphery of the first internal gear 22, together with the casing 24, functions as a casing that covers the interior of the flexible mesh gear device 1. The anti-output side of the first internal gear 22 has a protruding portion for connection to the first cover 26, and this portion is provided with a connecting hole 22h3 into which a connecting member (such as a bolt, the same applies below) 51 for connecting to the first cover 26 is screwed. Furthermore, the first internal gear 22 is provided on its outer periphery with a connecting hole 22h1 for connection to the casing 24 via a connecting member 53, and a connecting hole 22h2 for connection to an external support member by fastening together with the casing 24. Furthermore, the first internal gear 22 has a fitting surface 22e1 that is spigot-fitted with the casing 24, and a fitting surface 22e2 that is spigot-fitted with the first cover 26. The connecting holes 22h1 to 22h3 are formed with female threads when a connecting member is screwed into them, but do not need to have female threads when a connecting member is passed through them.

[0020] The second internal gear 23 has a mating surface 23s1 to which the inner ring 33a of the main bearing 33 is fixed on its outer periphery, an abutment surface 23s2 that determines the axial position of the inner ring 33a, a connecting hole 23h1 for connecting to an external member to be driven, a connecting hole 23h2 for connecting to the second cover 27, and a mating surface 23e that is spigot-fitted with the second cover 27.

[0021] The casing 24 is connected to the first internal gear 22 via a connecting member 53. The casing 24, together with the first internal gear 22, covers the radial outside of a portion where the teeth 22g, 23g of the first internal gear 22 and the second internal gear 23 mesh with the external gear 12. The casing 24 has a fitting surface 24s to which the outer ring 33b of the main bearing 33 is fixed, a connecting hole 24h1 into which the connecting member 53 screws, and a connecting hole 24h2 that communicates with the connecting hole 22h2 of the first internal gear 22.

[0022] The first cover 26 covers the outer periphery on the anti-output side of the vibrator shaft 10. The first cover 26 has a connecting hole 26h1 that communicates with the connecting hole 22h1 of the first internal gear 22, and is connected to the first internal gear 22 via a connecting member 51.

[0023] The second cover 27 covers the outer periphery on the output side of the vibrator shaft 10. The second cover 27 has connecting holes 27h1 and 27h2 that communicate with the connecting holes 23h1 and 23h2 of the second internal gear 23, respectively. The connecting hole 27h1 is a through hole for fastening the second cover 27 together with an external member to be driven and the second internal gear 23. The connecting hole 27h2 is a through hole that has a seat surface for the connecting member 52, and the connecting member 52 is passed through and threaded into the connecting hole 23h2 of the second internal gear 23, thereby connecting the second cover 27 alone to the second internal gear 23.

[0024] The input bearing 31 is disposed between the shaft portion 10B of the vibrator shaft 10 and the first cover 26. The first cover 26 rotatably supports the vibrator shaft 10 via the input bearing 31. The input bearing 32 is disposed between the shaft portion 10C of the vibrator shaft 10 and the second cover 27. The second cover 27 rotatably supports the vibrator shaft 10 via the input bearing 32.

[0025] The main bearing 33 has an inner ring 33a, an outer ring 33b, and rolling elements 33c, and is disposed between the second internal gear 23 and the casing 24. The casing 24 rotatably supports the second internal gear 23 via the main bearing 33. Although a ball bearing is shown as the main bearing 33 in FIG. 1, any type of bearing may be used, such as a roller bearing, a cross roller bearing, an angular contact ball bearing, or a tapered bearing. The outer ring 33b of the main bearing 33 may be configured integrally with the casing 24.

[0026] <Materials of each component> The second internal gear 23 is made of a resin material. The resin material can be a simple resin or a resin containing reinforcing fibers, such as PEEK (Poly Ether Ether Ketone) or POM (Polyacetal or Polyoxymethylene). Examples of resins containing reinforcing fibers include composite materials such as CFRP (Carbon Fiber Reinforced Plastics), composite materials of resin and other materials, and baked goods (paper baked goods, cloth baked goods, etc.). When the resin material is a simple resin or when the reinforcing fibers contained therein are fibers that are not bound together in a cloth-like form, the resin material can be injection molded or compression molded. When the material contained in the resin material is fibers that are bound together in a cloth-like or flake-like form, the resin material can be compression molded.

[0027] Although the materials of the other members are not particularly limited, in this embodiment they are configured as follows: The first internal gear 22, the casing 24, the first cover 26, and the second cover 27 are configured from any of the resin materials listed above. By using resin for these members, the cost and weight of the flexible mesh gear device 1 can be reduced.

[0028] The vibrator shaft 10, external gear 12, and spacer rings 36, 37 are made of metal materials such as steel. Although not particularly limited, more specifically, the vibrator shaft 10 is made of steel materials such as chromium-molybdenum steel. The external gear 12 is made of steel materials such as nickel-chromium-molybdenum steel. The spacer rings 36, 37 are made of steel materials such as high-carbon chromium bearing steel.

[0029] <Operation description> When the vibrator shaft 10 is driven to rotate by a drive source such as a motor, the motion of the vibrator 10A is transmitted to the external gear 12. At this time, the external gear 12 is constrained to a shape that follows the outer circumferential surface of the vibrator 10A and is bent into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. Furthermore, the external gear 12 is meshed with the fixed first internal gear 22 at its major axis portion. Therefore, the external gear 12 does not rotate at the same rotational speed as the vibrator 10A, and the vibrator 10A rotates relatively inside the external gear 12. Then, with this relative rotation, the external gear 12 is bent and deformed so that the major axis position and the minor axis position move circumferentially. The period of this deformation is proportional to the rotation period of the vibrator shaft 10.

[0030] When the external gear 12 flexes and deforms, the position of its major axis moves, causing the meshing position between the external gear 12 and the first internal gear 22 to change in the rotational direction. Here, for example, if the number of teeth of the external gear 12 is 100 and the number of teeth of the first internal gear 22 is 102, the meshing teeth of the external gear 12 and the first internal gear 22 will shift each time the meshing position makes one rotation, causing the external gear 12 to rotate (spin on its axis). With the above number of teeth, the rotational motion of the vibrator shaft 10 is decelerated at a reduction ratio of 100:2 and transmitted to the external gear 12.

[0031] Meanwhile, because the external gear 12 also meshes with the second internal gear 23, the meshing position between the external gear 12 and the second internal gear 23 also changes in the rotational direction due to the rotation of the vibrator shaft 10. If the number of teeth of the second internal gear 23 and the number of teeth of the external gear 12 are the same, the external gear 12 and the second internal gear 23 do not rotate relative to each other, and the rotational motion of the external gear 12 is transmitted to the second internal gear 23 at a reduction ratio of 1:1. As a result, the rotational motion of the vibrator shaft 10 is slowed down at a reduction ratio of 100:2 and transmitted to the second internal gear 23 and second cover 27, and this rotational motion is output to an external member to be driven.

[0032] <Details of the second internal gear> FIG. 2 shows a second internal gear according to an embodiment of the present invention, where (A) is a plan view thereof and (B) is a cross-sectional view taken along line AA.

[0033] As shown in FIG. 2, the second internal gear 23 has a flange portion 23A extending radially beyond the internal teeth 23g. Because the second internal gear 23 has internal teeth, the flange portion 23A extends radially outward beyond the teeth 23g. However, if the second internal gear 23 had external teeth, the flange portion 23A would extend radially inward beyond the teeth 23g. The flange portion 23A further has protruding portions 23Aa and 23Ab that protrude axially beyond the position of the teeth 23g on the output side and the anti-output side, respectively. The protruding portion 23Aa has multiple plate-shaped ribs r extending axially and radially and recessed portions p with gaps between adjacent ribs r. The recessed portions p are open on the output side. The flange portion 23A has the aforementioned connecting holes 23h1 and 23h2 and fitting surface 23e on the protruding portion 23Aa side. The other overhanging portion 23Ab is provided with the aforementioned contact surface 23s2, and the aforementioned fitting surface 23s1 is provided on the outer periphery of the flange portion 23A including the overhanging portion 23Ab.

[0034] The second internal gear 23 has a fluid solidified portion, the outer surface of which is formed by solidifying a molten resin material (i.e., a fluid material), and a machined portion, the outer surface of which is machined. The outer surface refers to the surface that comes into contact with air when the second internal gear 23 is viewed alone. Machined processing is a concept that includes polishing. Tool marks (tool traces) are added to the machined portion. On the other hand, the tool marks do not appear in the fluid solidified portion. The machined portion and the fluid solidified portion can be distinguished by the presence or absence of the tool marks. Furthermore, when the fluid solidified portion is formed by injection molding, one of the portions of the fluid solidified portion will include the shape of a gate portion through which the molten resin material passes when filling the mold.

[0035] The machined portion includes teeth 23g. The method for cutting the teeth 23g is not particularly limited, but includes, for example, tooth forming processing using a gear shaper, a skyping cutter, a hob, etc., and may also be grinding processing using a grindstone.

[0036] The fluid solidified portion includes surfaces (sites) other than the machined portion, such as the surface S1 on the anti-output side of flange portion 23A, the surface S2 on the output side, the inner peripheral surface S3 of protruding portion 23Aa, the surface inside hollowed-out portion p, contact surface 23s2, the outer peripheral surface S4 of protruding portion 23Ab, surfaces other than the female thread portions of connecting holes 23h1 and 23h2, fitting surface 23s1, fitting surface 23e, and the female thread portions of connecting holes 23h1 and 23h2.

[0037] The fluid solidification portion is formed by, for example, injection molding, but may also be formed by compression molding of a fiber-reinforced resin. The outer shape of the fluid solidification portion is formed to conform to the shape of the mold.

[0038] One or more of the mating surface 23s1, mating surface 23e, and the female thread portions of the connecting holes 23h1 and 23h2 may be included in the machined portion rather than the fluid-solidified portion. When the mating surface 23s1 or the mating surface 23e is machined, the machined portion includes polishing using a grindstone or the like. By machining the mating surface 23s1 or the mating surface 23e, the dimensional accuracy of the mating structure via this surface is improved.

[0039] The machined portion of the second internal gear 23 has an area ratio of, for example, 50% or less, and preferably 30% or less, to the entire outer surface of the second internal gear 23. It is even more preferable that only the teeth 23g are machined, and that the shape of the gear intermediate (see FIG. 3(B) and gear intermediate IN in FIG. 4) other than the teeth is maintained in the finished gear (second internal gear 23). While machined portions can achieve high machining precision, they also require additional processes, increasing costs. By setting the area ratio of the machined portion to the above ratio, it is possible to achieve high machining precision in the required areas while maintaining the advantage of being able to manufacture the second internal gear 23 at low cost.

[0040] <Details of the first internal gear> The first internal gear 22 has a fluid-solidified portion, the outer surface of which is formed by solidifying a molten resin material, and a machined portion, the outer surface of which is machined. In the first internal gear 22, the machined portion includes teeth 22g. The machined portion may include one or more of the female thread portion of the connecting hole 22h1 and the mating surfaces 22e1 and 22e2. The fluid-solidified portion of the first internal gear 22 corresponds to the portion other than the machined portion. The fluid-solidified portion and the machined portion can be distinguished in the same manner as described for the second internal gear 23. In the first internal gear 22, the machined portion of the first internal gear 22 also accounts for, for example, 50% or less, and preferably 30% or less, of the area of ​​the entire outer surface of the first internal gear 22. Furthermore, it is more preferable that only the teeth 22g are machined, and that the shape of the portion of the gear intermediate other than the teeth is maintained in the finished gear (first internal gear 22).

[0041] <Gear manufacturing method> 3A and 3B are diagrams illustrating the manufacturing process of the second internal gear, in which (A) shows the injection molding step, (B) shows the gear intermediate body released from the mold, and (C) shows the tooth cutting step. Fig. 4 is a plan view showing the gear intermediate body.

[0042] The gear manufacturing method of this embodiment includes an intermediate body forming process J1 in which a gear intermediate body IN is formed by solidifying a molten resin material, which is a fluid material, as shown in Figures 3(A) and (B), and a tooth forming process J2 in which teeth 23g are formed on the gear intermediate body IN by cutting, as shown in Figure 3(C).

[0043] As shown in FIG. 3(A), the intermediate forming step J1 is an injection molding step in which molten resin material is fed from an injection nozzle N1 into the cavity of a mold E1 and solidified within the mold E1. Mold E1 is opened and the molded product is released, resulting in a gear intermediate IN shaped to fit the cavity of the mold E1. Note that the intermediate forming step J1 may also be a compression molding step. In this embodiment, the resin material (e.g., PEEK material) contains reinforcing fibers (e.g., carbon fibers), and the material of the gear intermediate IN may be a fiber-reinforced resin.

[0044] As shown in Figures 3(B) and 4, the gear intermediate IN has a thick portion M1 at a location that will become the tooth 23g. The thick portion M1 is radially thicker than the tooth height of the tooth 23g and has no irregularities on its surface (inner peripheral surface). Note that the thick portion M1 may have irregularities corresponding to the tooth bottom and tooth tip of the tooth 23g and may have a radial thickness greater than that of the tooth 23g. By forming the irregularities in advance, stress concentration in the thick portion M1 during molding can be suppressed.

[0045] Furthermore, when portions other than the teeth 23g, such as the fitting surface 23s1 or the fitting surface 23e, are subjected to the cutting process, thick portions M2 and M3 that are thicker by the amount of cutting (polishing) are formed in these portions of the gear intermediate IN. The portions other than the thick portions M1 to M3 have the same shape as the second internal gear 23 in its final form.

[0046] In the tooth forming step J2, as shown in Fig. 3(C), teeth 23g are formed by cutting the thick portion M1 (the smooth inner peripheral surface thereof) of the gear intermediate IN using a gear shaper C. Note that the tooth forming step J2 may use another tool such as a skyping cutter or a hob, or may include a grinding step using a grinding stone.

[0047] The gear manufacturing method of this embodiment may further include a cutting step for the portions requiring high dimensional accuracy. For example, in this cutting step, the mating surface 23s1 or the mating surface 23e of the gear intermediate IN is cut (e.g., polished with a grindstone). This step may be performed before or after the tooth forming step J2, or may be performed in parallel with the tooth forming step J2.

[0048] The second internal gear 23 of the flexible mesh gear device 1 of this embodiment is manufactured through the above-described multiple steps. The first internal gear 22 may also be manufactured through the same steps as above. Furthermore, the internal gears or external gears included in various gear devices may also be manufactured through the same steps as above.

[0049] As described above, the gear manufacturing method of this embodiment includes an intermediate forming step J1 in which a fluid material is solidified to form a gear intermediate IN, and a tooth forming step J2 in which teeth 23g are formed on the gear intermediate IN by cutting. In the intermediate forming step J1, the gear intermediate IN is formed by solidifying a fluid material, which has the effect of reducing manufacturing costs. On the other hand, even if the dimensional accuracy is reduced in the step of solidifying the fluid material, the teeth 23g can be machined with high precision in the tooth forming step J2. Therefore, a gear (second internal gear 23) that can be used in a high-precision gear device can be manufactured at low manufacturing cost.

[0050] Furthermore, according to the gear manufacturing method of this embodiment, the gear intermediate IN is formed by injection molding in the intermediate forming step J1. Injection molding makes it possible to form the gear intermediate IN at low cost and with little variation in quality. This improves yield and makes it possible to manufacture a gear (second internal gear 23) that can be used in high-precision gear devices at lower manufacturing costs.

[0051] Furthermore, according to the gear manufacturing method of this embodiment, the resin material contains reinforcing fibers. Therefore, high-strength gears suitable for high-torque gear devices can be manufactured. Let's assume that the teeth 23g are formed by injection molding using a resin material containing reinforcing fibers. In this case, to achieve a fine shape at the tooth tip and tooth root, the fiber length must be short, otherwise the distribution rate of the reinforcing fibers on the surface of the tooth 22g would be reduced, placing restrictions on the fiber length. On the other hand, according to the gear manufacturing method of this embodiment, the molding process of solidifying the resin material does not require the formation of fine teeth 23g. Since the teeth 23g are formed by cutting, even if long reinforcing fibers are used, a good fiber distribution can be achieved throughout the entire tooth 23g. This allows for the manufacture of high-precision, high-strength gears.

[0052] Furthermore, according to the gear manufacturing method of this embodiment, the thick portion M1 where the teeth 23g of the gear intermediate IN are formed has a smooth surface. This makes it easy to fill the thick portion M1 with molten resin material when filling the mold E1. Furthermore, even if the resin material contains reinforcing fibers, the thick portion M1 can be easily filled with the resin material with good fiber distribution. Therefore, the subsequent cutting process can produce high-strength teeth 23g with little variation in quality.

[0053] Furthermore, the gear manufacturing method of this embodiment is used to manufacture the second internal gear 23 of the flexible mesh gear device 1. The flexible mesh gear device 1 can achieve high-precision operation with little backlash thanks to high-precision gears. Therefore, by applying the lightweight, high-precision, and low-cost second internal gear 23 manufactured by the manufacturing method of this embodiment, a lightweight, high-precision, and low-cost flexible mesh gear device 1 can be realized.

[0054] The second internal gear 23 of this embodiment has a fluid-solidified portion whose outer surface is formed by solidifying a resin material, and a machined portion whose outer surface is machined, and the machined portion includes teeth 23g. Therefore, the fluid-solidified portion reduces costs, while realizing a second internal gear 23 with high dimensional accuracy of the teeth 23g. Furthermore, the flexible mesh gear device 1 having the second internal gear 23 can achieve high-precision operation while reducing the weight and cost of the device.

[0055] The above describes embodiments of the present invention. However, the present invention is not limited to the above embodiments. For example, in the gear manufacturing method of the above embodiment, a gear intermediate IN is formed by injection molding a fluid material. However, the intermediate formation step may be performed using any molding method, such as compression molding or molding using a 3D printer, as long as it can solidify a fluid material (including melting a powder or granular material to form a fluid) to form a gear intermediate. In addition, in the gear manufacturing method of the above embodiment, the mating surface 23s1 to which the inner ring 33a of the main bearing 33 is fixed is described as the surface to be machined. However, if there is a mating surface to which the outer ring of the bearing is fixed, this surface may be machined. Furthermore, the entire connecting hole may be machined. Furthermore, in the above embodiment, a resin material is described as the fluid material constituting the gear. However, the gear intermediate may be formed by a molding method such as aluminum die casting, casting, or 3D printing using a molten metal, such as molten aluminum or molten iron, as the fluid material. Even in this case, the inclusion of a process for solidifying and molding the fluid material reduces the cost of the gear, while the tooth forming process by cutting allows for high precision in the dimensions and shape of the teeth. While the embodiment has been described using an internal gear of a flexible mesh gear device as an example, the gears that are the subject of the present invention are not particularly limited, and can also be applied to, for example, external gears and orthogonal gears. Other details shown in the embodiment can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0056] 1. Flexible mesh gear device 10A vibrator 12 External gear 15 Vibrator bearing 22 First internal gear 22e1, 22e2 mating surface 22g tooth 22h1~22h3 Connection hole 23 Second internal gear 23A flange 23Aa, 23Ab protruding parts 23e Mating surface 23g tooth 23h1, 23h2 connection hole 23s1 Mating surface 23s2 Contact surface 33 Main bearing 33a Inner circle J1 Intermediate formation process E1 type IN gear intermediate body r Rib p Hollowed-out section J2 Tooth formation process M1~M3 Thick part

Claims

1. A gear manufacturing method for manufacturing an internal gear, comprising: an intermediate forming step of solidifying a fluid material, which is molten resin or aluminum, to form a gear intermediate; a tooth forming step of forming teeth on the gear intermediate body by cutting; a cutting process for cutting at least one of a fitting surface of the gear intermediate body to which another member is spigot-fitted and a fitting surface to which a bearing is fixed; A method for manufacturing a gear comprising the steps of:

2. In the intermediate body forming step, the gear intermediate body is formed by injection molding a resin material. The method for manufacturing a gear according to claim 1.

3. The resin material contains reinforcing fibers. The method for manufacturing a gear according to claim 2.

4. In the intermediate forming step, a surface without irregularities is formed in the area where teeth are to be formed, In the tooth forming step, teeth are formed on the smooth surface. The method for manufacturing a gear according to any one of claims 1 to 3.

5. The internal gear is an internal gear of a flexible meshing gear device, The method for manufacturing a gear according to any one of claims 1 to 4.

6. A gear having a fluid solidification portion whose outer shape is formed by solidifying a fluid material that is molten resin or aluminum, and a machined portion that is machined, the gear is an internal gear, The machined portion of the gear includes teeth and at least one of a fitting surface to which another member is spigot-fitted and a fitting surface to which a bearing is fixed.

7. 7. The gear according to claim 6, wherein the area ratio of the machined portion to the entire outer surface of the gear is 50% or less.

8. A flexible meshing gear device including a vibration exciter, an external gear that is flexibly deformed by the vibration exciter, and an internal gear that meshes with the external gear, The internal gear has a fluid solidified portion whose outer shape is formed by solidifying a fluid material that is molten resin or aluminum, and a machined portion that is machined, The machined portion includes teeth and at least one of a fitting surface to which another member is spigot-fitted and a fitting surface to which a bearing is fixed.

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