JPWO2018180185A1 - Resin gear and gear mechanism - Google Patents

Abstract

One embodiment of the resin gear of the present invention is a carbon fiber made of a mixed material of a resin material and a carbon material, wherein the carbon material has a length of 100 μm or less.

Description

The present invention relates to a resin gear and a gear mechanism.

Conventionally, in the case of gears using a metal material, there has been a problem of vibration and noise caused by backlash. Therefore, in order to reduce vibration and noise caused by backlash, in recent years, it has been proposed to apply a gear using a resin material.

Further, in order to transmit a large stress, there is a demand for improving the durability and wear resistance of the resin gear. As one means for improving the durability and abrasion resistance of the resin gear, for example, as in Patent Document 1, a method of improving the durability and abrasion resistance by mixing a reinforcing fiber with a resin material is studied. Have been.

Re-published WO2004 / 083015

However, when the gear is small, there is a problem that the reinforcing fiber does not spread to every corner of the gear structure at the time of injection molding, and the reinforcing effect of the reinforcing fiber cannot be obtained at the tip portion of the tooth. Further, when the reinforcing fibers are long, for example, the reinforcing fibers are entangled with each other, causing a bias, or a void is easily generated in the resin material, and a dimensional change amount upon heat shrinkage depending on the direction during thermosetting. There was also a problem that was changed.

In addition, if backlash occurs due to the accuracy of meshing between the gears, the performance of the gear structure may be reduced. In particular, in the case of a cycloid-type small speed reducer, there is a case where the transmission of the driving force is delayed or an agile operation such as an instantaneous stop cannot be performed. Therefore, high dimensional accuracy of each gear is required.

One aspect of the present invention is to provide a resin gear having high dimensional accuracy while having sufficient durability and abrasion resistance even in a small size by containing a reinforcing fiber, in view of the above problems, and including the same. Another object of the present invention is to provide a gear mechanism.

One embodiment of the resin gear of the present invention is a carbon fiber made of a mixed material of a resin material and a carbon material, wherein the carbon material has a length of 100 μm or less.

According to one embodiment of the present invention, it is possible to provide a resin gear having sufficient durability and wear resistance and high dimensional accuracy even if it is small, and a gear mechanism provided with the resin gear.

FIG. 1 is a diagram showing a configuration of a part of a small reduction gear 100 in which a resin gear according to the present invention is applied as an internal gear 10. The figure which shows the internal gear 10. It is a figure which shows a mode that the carbon fiber 12 was disperse | distributed in an irregular direction, and is an enlarged view of one internal tooth. The figure which shows the external gear 20. It is a figure which shows a mode that the carbon fiber 12 was disperse | distributed in a regular direction, and is an enlarged view of one internal tooth. FIG. 3 is an enlarged view showing a part of the surface of the internal teeth 13 of the internal gear 10 before use. FIG. 3 is an enlarged view showing a part of the surface of the internal teeth 13 of the internal gear 10 before use. FIG. 3 is an enlarged view showing a state in which the external gear meshes with the internal gear 10 during use.

The resin gear according to the present invention is made of a mixed material of a resin material and a carbon material. Carbon fiber is used as a carbon material, and many carbon fibers are mixed with a resin material. Such a resin gear can be suitably used, for example, as the internal gear 10 of the small reduction gear 100 as shown in FIG.

Hereinafter, a configuration of a small reduction gear according to an embodiment of the present invention will be described with reference to the drawings. It should be noted that the scope of the present invention is not limited to the following embodiment, and can be arbitrarily changed within the technical idea of the present invention. Further, in the following drawings, in order to make each configuration easy to understand, the scale and the number of the actual structure may be different from those of the actual structure.

In the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is a direction parallel to the axial direction of the first central axis J1 and the second central axis J2 shown in FIG. The X-axis direction is a direction orthogonal to the Z-axis direction and is the left-right direction in FIG. The Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction, and is the up-down direction in FIG.

In the following description, a direction (Z-axis direction) parallel to the first center axis J1 and the second center axis J2 is simply referred to as “axial direction”, and the first center axis J1 or the second center axis J2 is used as a center. The radial direction referred to simply as “radial direction” is referred to as a “radial direction”. Circumferential direction ".

(Small Reducer) FIG. 1 is a view showing a partial configuration of a small reducer 100 in which the resin gear of the embodiment is applied as an internal gear 10. As shown in FIG. 1, the small speed reducer (gear mechanism) 100 includes at least an internal gear 10, an external gear 20, a shaft 7, and a plurality of support pins 8. The shaft 7 is an input shaft of the small reduction gear 100, and includes a shaft main body (not shown) extending along the first central axis J1 and an eccentric portion 7B provided at a tip of the shaft main body and extending along the second central axis J2. And

(Internal Gear 10) FIG. 2 is a diagram showing the internal gear 10. The internal gear 10 is an embodiment of the resin gear according to the present invention. As shown in FIGS. 1 and 2, the internal gear (resin gear) 10 extends from a cylindrical internal gear main body 10A around the first central axis J1 and a part of the internal gear main body 10A. And a fixed member 10B. A plurality of internal teeth 13 projecting radially outward from the inner peripheral surface 10a are provided on the inner peripheral surface 10a of the internal gear main body 10A. Between the adjacent internal teeth 13 in the circumferential direction, there is provided an internal inter-tooth groove 14 that is recessed radially inward (inner peripheral surface 10a). The internal teeth 13 and the internal inter-tooth grooves 14 alternately exist around the first central axis J1. The diameter of the addendum circle of the internal gear 10 is, for example, not less than 2 mm and not more than 12 mm.

As shown in FIG. 1, the internal gear body 10A surrounds the external gear 20 radially outside. The internal teeth 13 of the internal gear main body 10 </ b> A face the external teeth 22 of the external gear 20, and partially mesh in the circumferential direction sequentially according to the swinging operation of the external gear 20.

(Material of Internal Gear) FIG. 3 is a diagram showing a state where the carbon fibers 12 are dispersed in an irregular direction in the configuration of the present embodiment, and is an enlarged view of one internal gear.

The internal gear 10 is an embodiment of the resin gear according to the present invention. The internal gear 10 is a resin gear made of a reinforced resin containing a carbon material. As a material of the internal gear 10, a resin material 11 (FIG. 3) is used as a base material, and carbon fibers (carbon material) 12 (FIG. 3) are used as an additive to the base material.

As the resin material 11 used for the base material, a polymer material having excellent moldability and high mechanical strength is selected. Specific resin materials 11 include, for example, crystalline super engineering plastics such as PEEK (Poly ether ether ketone) polyether ether ketone resin, LCP (Liquid Crystal Polymer liquid crystal polymer), and PPS (Poly Phenylene Sulfide Resin polyphenylene sulfide resin). And one or more materials selected from the group consisting of polyamide resins such as semi-aromatic nylon (PA4T, PA6T, PA9T, PA10T) and polyamide 46 (PA46).

As the carbon fiber 12, it is desirable to use a PAN-based carbon fiber 12 having high strength and excellent wear resistance. As the carbon fiber 12, for example, a fine carbon fiber having an average aspect ratio of 5 to 20 and an average fiber length of 100 μm or less is selected. More specifically, short fibers having an average aspect ratio of 10 or less, an average fiber length of 80 μm, and an average fiber diameter of 5 to 7 μm may be selected. As the carbon fiber 12, anisotropic pitch-based carbon fiber 12 can be used particularly for the purpose of obtaining strength. As the carbon fiber 12, for example, a fine carbon fiber having an average aspect ratio of 5 to 15 and an average fiber length of 100 μm or less is selected. More specifically, short fibers having an average aspect ratio of 10 or less, an average fiber length of 80 μm, and an average fiber diameter of 7 to 11 μm may be selected.

Here, with the average aspect ratio, the length in the radial direction orthogonal to the length direction of the carbon fiber 12 is defined as a diameter r (μm), and the length of the carbon fiber 12 in the length direction is defined as a length L (μm). This is a value obtained by averaging the L / r ratios for a plurality of carbon fibers 12 included in a predetermined range. The aspect ratio of one fiber can be calculated by observing the carbon fiber 12 and dividing the length of the carbon fiber 12 by the diameter.

The length of the carbon fiber 12 can be measured using an optical microscope or an electron microscope. For example, using a scanning electron microscope (SEM), for example, 100 arbitrary carbon fibers 12 having a length of 100 μm or less are selected, and the length and diameter of the carbon fibers 12 are measured. From the measured lengths and diameters, the aspect ratios of the 100 carbon fibers 12 are obtained, and the average aspect ratio can be calculated as the average of those aspect ratios.

Since the fine carbon fibers 12 are fibers having a small aspect ratio, the carbon fibers 12 have a very good dispersibility in the resin material 11 and are distributed in the resin material 11 in a uniform state. Further, since the aspect ratio is small, anisotropy does not appear in the dispersion direction of the carbon fibers 12 in the resin material 11, and as shown in FIG. 3, the carbon fibers 12 are randomly dispersed in the injection molded article in an irregular direction. ing. Thereby, the internal gear 10 with high strength and high dimensional accuracy can be obtained.

In the present embodiment, the above-described base material contains 20 to 70% by volume of the carbon fiber 12 as the carbon material (reinforced material). More preferably, the content is 30 to 60% by volume. More preferably, it is 50% by volume. If the content of the carbon fiber 12 is less than 20% by volume, a desired reinforcing effect cannot be obtained. On the other hand, when the content of the carbon fibers 12 exceeds 70% by volume, voids are generated due to an insufficient amount of the resin connecting the fibers, which may affect the moldability and dimensional accuracy of the gear.

(External Gear 20) FIG. 4 is a diagram showing the external gear 20. The external gear 20 is a cycloid gear. As shown in FIGS. 1 and 4, the external gear 20 has a substantially annular plate shape that expands in the radial direction from the second central axis J2. A plurality of external teeth 22 protruding radially outward are provided on the outer periphery of the external gear 20. Further, between the external teeth 22 that are adjacent in the circumferential direction, an external tooth groove 23 that is recessed inward in the radial direction is provided. The external teeth 22 and the external interdental grooves 23 alternately exist around the axis of the second central axis J2. The addendum circle diameter of the external gear 20 is, for example, not less than 2 mm and not more than 12 mm.

The external gear 20 has a shaft insertion hole 24 penetrating in the axial direction (Z-axis direction) at a central portion. The shaft insertion hole 24 is a shaft hole that rotatably supports the eccentric portion 7B of the shaft 7 in FIG. 1 that extends along the second central axis J2. The shaft insertion hole 24 is a slide bearing, and holds the lubricating oil 19 (FIG. 8) inside.

The external gear 20 has a plurality of through holes 25 around the shaft insertion hole 24. The plurality of through-holes 25 are arranged at regular intervals along the circumferential direction around the second central axis J2 at positions radially outward from the shaft insertion hole 24. The radial positions of the through holes 25 are the same.

In this embodiment, about ten through holes 25 are provided, but the number is not limited to this. The shape of the through-hole 25 as viewed from the axial direction (Z-axis direction) is circular. The plurality of through holes 25 are slide bearings, and hold the lubricating oil 19 (FIG. 8) inside.

The support pins 8 shown in FIG. 1 are inserted into each of the plurality of through holes 25. The inner diameter of the through hole 25 is larger than the outer diameter of the support pin 8. The outer peripheral surface 8b of the support pin 8 is in contact with the inner peripheral surface 25a of the through hole 25. The support pin 8 restricts the free rotation of the external gear 20 and swings the external gear 20 around the first central axis J1. The support pin 8 is connected to an output shaft of the small speed reducer 100. The external gear 20 meshes with the internal gear 10 arranged radially outward.

(Material of External Gear 20) As a material of the external gear 20, a polymer material having excellent moldability and high mechanical strength is selected. Specific resin materials include, for example, crystalline super engineering plastics such as PEEK (Poly ether ether ketone) polyether ether ketone resin), LCP (Liquid Crystal Polymer liquid crystal polymer), PPS (Poly Phenylene Sulfide Resin polyphenylene sulfide resin) and the like. And one or more materials selected from the group consisting of polyamide resins such as semi-aromatic nylon (PA4T, PA6T, PA9T, PA10T) and polyamide 46 (PA46).

Preferably, the external gear 20 contains a carbon material. As the material of the external gear 20, the wear resistance of the external gear 20 can be increased by using a reinforcing material obtained by adding spherical amorphous carbon (not shown) to the above-described resin material. As the spherical amorphous carbon, carbon fine particles having an average aspect ratio of 2 or less are preferable.

The base material of the internal gear 10 described above may be the same as or different from the base material of the external gear 20.

In the small reduction gear 100 according to the present embodiment, for example, when the shaft 7 shown in FIG. 1 rotates around the first central axis J1, the inside of the through-hole 25 of the external gear 20 supported by the eccentric portion of the shaft 7 is formed. The external gear 20 swings in the radial direction while the position where the peripheral surface 25a and the outer peripheral surface 8b of the support pin 8 are in contact changes. Due to this swing, the position where the external teeth 22 of the external gear 20 mesh with the internal teeth 13 of the internal gear 10 changes in the circumferential direction. Here, every time the shaft 7 makes one rotation around the axis of the second center axis J2, the position where the teeth mesh with each other in the circumferential direction shifts. As a result, the output shaft connected to the support pin 8 rotates at, for example, 1/30 the speed of the shaft 7. The above-described operation of the small speed reducer 100 is an example, and may be configured to perform another operation.

FIG. 5 is a diagram showing a state in which carbon fibers 12 are dispersed in a regular direction in a conventional configuration, and is an enlarged view of one internal tooth. Here, in the conventional internal gear 90, as shown in FIG. 5, a long carbon fiber 92 having a fiber length exceeding 100 μm was added to the resin material 11. When a large number of carbon fibers 92 having a fiber length exceeding 100 μm are added to the resin material 11, the carbon fibers 92 are oriented in a regular direction along the flow of the resin material 11 during injection molding, as shown in FIG. There is a possibility that a large crack 91 is likely to occur. As described above, when the length of the carbon fiber 92 is long, the carbon fiber 92 is oriented in the flow direction along the flow of the resin material 11, and the contraction anisotropy due to the flow state of the resin material 11 occurs. In addition, the dimensional accuracy of the internal gear 90 is reduced, and it is difficult to obtain the target dimensions. If the length of the carbon fibers 92 is long, the carbon fibers 92 are entangled with each other, causing the carbon fibers 92 to be deviated, and voids are likely to be formed in the resin material 11. This changes the amount of dimensional change during heat shrinkage. Further, if a void remains inside the manufactured internal gear 90, the strength of the internal gear 90 will be reduced.

On the other hand, in the present embodiment, as shown in FIG. 4, the above-described problem was solved by adding the short carbon fiber 12 having a fiber length of 100 μm or less to the resin material 11. As in the present embodiment, the carbon fibers 12 having a short fiber length are dispersed in the resin material 11 in an irregular direction regardless of the outflow direction of the resin material 11 during injection molding. Since the carbon fibers 12 are not easily entangled with each other, no anisotropy appears in the dispersion direction of the carbon fibers 12 in the resin material 11 at the time of injection molding, and no deviation of the carbon fibers 12 and no voids are generated in the resin material 11. . For this reason, the amount of dimensional change at the time of heat shrinkage accompanying hardening becomes uniform, and the internal gear 10 with high dimensional accuracy can be formed.

In addition, since the carbon fiber 12 spreads to every corner of the internal gear 10 during injection molding, a sufficient reinforcing effect can be obtained even at the tips of the plurality of internal teeth 13, and the durability of the internal gear 10 is improved. Thus, no crack is generated in each internal tooth 13. In particular, since the external gear 20 which is a cycloid gear meshes with the internal gear 10, durability and high dimensional accuracy are required, but both can be realized in the present embodiment.

Further, by adding the carbon fibers 12 to the resin material 11, the coefficient of thermal expansion becomes lower than when only the resin material 11 is used. Therefore, a dimensional change of the internal gear 10 due to heat generation during use is suppressed.

In the miniature reduction gear 100 of the present embodiment including the above-described internal gear 10 and external gear 20, backlash due to the engagement accuracy between the internal gear 10 and the external gear 20 is unlikely to occur. Therefore, there is no delay in the transmission of the driving force from the input shaft to the output shaft of the small speed reducer 100, and an agile operation such as instantaneous stop can be performed.

Further, in the present embodiment, not only the internal gear 10 but also the external gear 20 is formed of a fiber reinforced material. Since the external gear 20 receives both a compressive force and a shear force, durability and slidability are important. Therefore, by adding a carbon material to the resin material 11, the durability and wear resistance of the external gear 20 can be improved.

FIG. 6 is an enlarged view showing a part of the surface of the internal teeth 13 of the internal gear 10 before use. FIG. 7 is an enlarged view showing a part of the surface of the internal teeth 13 of the internal gear 10 after use. FIG. 8 is an enlarged view showing a state in which the external gear 20 meshes with the internal gear 10 during use.

In the small speed reducer 100, the external gear 20 meshes with the internal gear 10, so that friction occurs between the internal gear 10 and the external gear 20, and the surface of the internal gear 10, that is, the internal gear Thirteen tooth surfaces wear. When the internal gear 10 wears, the relatively soft resin material 11 is preferentially shaved, so that the hard carbon fibers 12 partially protrude outward from the surface of each internal tooth 13. As shown in FIG. 6, the high-hardness carbon fiber 12 buried in the resin material 11 appears on the surface as shown in FIG. 7, and a gap 15 is generated between the carbon fiber 12 and the resin material 11. . Then, as shown in FIG. 8, the lubricating oil 19 is held in the gap 15 formed on the surface of each internal tooth 13 by capillary action.

On the other hand, the surface on the side of the external gear 20 also wears. Similarly to the internal gear 10, also in the external gear 20, the carbon material buried in the resin material 11 appears on the surface of each external tooth 22, and a gap 15 is generated between the external gear 22 and the carbon fiber 12. Therefore, as shown in FIG. 8, the lubricating oil 19 is also held in the gaps 15 formed on the surfaces of the external teeth 22 by capillary action. Further, the lubricating oil 19 is also temporarily held in the gap 16 between the internal gear 10 and the external gear 20 meshed with a part of the internal gear 10 by capillary action.

As described above, since the lubricating oil 19 is retained in the gaps 15 and 16, the slidability of the external gear 20 is improved, fatigue due to friction is suppressed, and the life of each gear 10 and 20 is extended. It becomes possible.

As described above, the small speed reducer 100 of the present embodiment includes the internal gear 10 including the carbon fiber 12 and the external gear 20 including the spherical amorphous carbon. A gear structure having high durability and abrasion resistance and high dimensional accuracy can be obtained, and the small reduction gear 100 with high reliability can be obtained.

As mentioned above, although one Embodiment of this invention was described, each structure in embodiment, their combination, etc. are an example, and addition, abbreviation, substitution, and other addition of a structure do not deviate from the meaning of this invention. Changes are possible. The present invention is not limited by the embodiments.

For example, in the above-described embodiment, only the carbon fiber 12 is mixed with the resin material 11 as the carbon material in the internal gear 10. However, not only the carbon fiber 12 but also spherical amorphous carbon may be mixed with the resin material 11. Good. The addition ratio of the carbon fiber 12 and the spherical amorphous carbon to the resin material 11 is appropriately selected in consideration of the formability and the dimensional accuracy of the internal gear 10 and the like.

Thus, by mixing not only carbon fibers but also spherical amorphous carbon into the resin material 11, the density of the carbon material in the resin material 11 is improved. Accordingly, since the strength of the external gear 20 can be increased, the durability and wear resistance of the external gear 20 are further improved.

In the external gear 20, only the spherical amorphous carbon is mixed with the resin material 11, but not only the spherical amorphous carbon but also the carbon fiber 12 may be mixed.

Reference numeral 10: internal gear (resin gear), 11: resin material, 12: carbon fiber (carbon material), 20: external gear, 100: small reduction gear (gear mechanism)

Claims (8)

A resin gear comprising a mixed material of a resin material and a carbon material, wherein the carbon material is a carbon fiber having a length of 100 μm or less. The resin gear according to claim 1, wherein the resin gear is an internal gear, and has a plurality of internal teeth protruding radially outward. The resin gear according to claim 1, wherein the carbon material is dispersed in the resin material in an irregular direction. The resin gear according to claim 2, wherein an outer diameter is 12 mm or less. The resin gear according to any one of claims 1 to 4, wherein the carbon material has an average aspect ratio of 5 or more and 15 or less. The resin gear according to claim 1, wherein a content of the carbon material in the resin material is in a range of 20% by weight to 60% by weight. The resin gear according to claim 1, further comprising spherical amorphous carbon. A resin gear according to any one of claims 1 to 7, wherein the internal gear is an internal gear, a gear mechanism having an external gear disposed radially inside the internal gear, wherein the external gear includes a resin material and A gear mechanism made of a mixed material with spherical amorphous carbon.

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