JP5988424B2 - Eccentric oscillating gear unit - Google Patents

Description

  The present invention relates to an eccentric oscillating gear device.

  Conventionally, as disclosed in Patent Document 1 below, an eccentric oscillating gear device is known that reduces the rotational speed at a predetermined reduction ratio between two counterpart members. The eccentric oscillating gear device includes an outer cylinder fixed to one counterpart member, and a carrier disposed in the outer cylinder and fixed to the other counterpart member. Rotating relative to the outer cylinder by the swinging rotation of the swinging gear attached to the eccentric part of the crankshaft.

JP 2006-77980 A

  In recent years, the operating rate of robots tends to be increased due to changes in the usage environment of the robots, and accordingly, speeding up of reduction gears is also required. In the eccentric oscillating gear device, the temperature in the carrier becomes higher than the temperature of the outer cylinder during use. For this reason, the oscillating gear thermally expands in use, but this thermal expansion narrows the gap between the outer teeth of the oscillating gear and the inner teeth of the outer cylinder, and the surface pressure of the tooth surface of the oscillating gear is reduced. As a result, there is a problem that the life of the oscillating gear is reduced.

  Therefore, the present invention has been made in view of the above-described prior art, and an object of the present invention is to prevent the life of the oscillating gear from being increased by suppressing an increase in the surface pressure of the tooth surface of the oscillating gear. It is in suppressing shortening.

In order to achieve the above object, the present invention provides a gear device that transmits a driving force by converting a rotational speed at a predetermined rotational speed ratio between a first member and a second member. And an oscillating gear that is made of an iron-based material having a carbon content of 0.7 to 1.0%, has an insertion hole into which the eccentric portion is inserted, and has a tooth portion, the first member, and the A first cylinder part configured to be attachable to one of the second members, and a second cylinder part configured to be attachable to the other of the first member and the second member, The one cylindrical portion is made of an iron-based material having a linear expansion coefficient larger than that of the material of the oscillating gear and having a carbon content of 0.2% or less, and an internal tooth that meshes with the tooth portion of the oscillating gear. And the second cylinder part is disposed radially inward of the first cylinder part while holding the swing gear, And said second cylindrical portion and the first cylindrical portion, a eccentrically oscillating gear device is rotatable relative to one another concentrically by the swinging of the swing gear according to the rotation of the eccentric portion.

  In this invention, the linear expansion coefficient of the raw material which comprises a rocking gear is smaller than the linear expansion coefficient of the raw material which comprises a 1st cylinder part. Therefore, when the temperature of the first tube portion, the second tube portion, and the swing gear is raised during use of the eccentric swing gear device, the first tube portion expands more than the swing gear. For this reason, the clearance between the internal teeth of the first tube portion and the tooth portion of the swing gear, that is, the clearance between the inner peripheral surface of the first tube portion and the swing gear is narrower than that before use. Never become. Therefore, even if the oscillating gear is heated and expanded, the surface pressure of the tooth surface of the oscillating gear can be prevented from increasing, and the life of the oscillating gear can be prevented from being shortened. .

  As described above, according to the present invention, an increase in the surface pressure of the tooth surface of the oscillating gear can be suppressed, so that the life of the oscillating gear can be prevented from being shortened.

It is sectional drawing which shows the structure of the eccentric rocking | fluctuation type gear apparatus which concerns on embodiment of this invention. It is sectional drawing in the II-II line of FIG.

  Hereinafter, an eccentric oscillating gear device according to an embodiment of the present invention will be described in detail with reference to the drawings. An eccentric oscillating gear device (hereinafter referred to as a gear device) 1 according to this embodiment is applied as a speed reducer to, for example, a revolving part of a revolving trunk or arm joint of a robot, a revolving part of various machine tools, or the like. is there. The gear device 1 is used at a rotational speed of, for example, 80 rpm to 200 rpm.

  The gear device 1 according to the present embodiment rotates the crankshaft 10 by rotating the input shaft 8, and swings and rotates the swing gears 14 and 16 in conjunction with the eccentric portions 10a and 10b of the crankshaft 10. Thus, an output rotation decelerated from the input rotation is obtained.

  As shown in FIGS. 1 and 2, the gear device 1 includes an outer cylinder 2 that is an example of a first cylinder part, a carrier 4 that is an example of a second cylinder part, an input shaft 8, and a plurality (for example, three). The crankshaft 10, the first oscillating gear 14, the second oscillating gear 16, and a plurality of (for example, three) transmission gears 20 are provided.

  The outer cylinder 2 constitutes the outer surface of the gear device 1 and has a substantially cylindrical shape. A large number of pin grooves 2 b are formed on the inner peripheral surface of the outer cylinder 2. Each pin groove 2b is disposed so as to extend in the axial direction of the outer cylinder 2, and has a semicircular cross-sectional shape in a cross section orthogonal to the axial direction. These pin grooves 2 b are arranged on the inner peripheral surface of the outer cylinder 2 at equal intervals in the circumferential direction.

  The outer cylinder 2 has a large number of internal tooth pins 3. Each internal tooth pin 3 is attached to a pin groove 2b. Specifically, each internal tooth pin 3 is fitted in the corresponding pin groove 2 b and is arranged in a posture extending in the axial direction of the outer cylinder 2. Thereby, the many internal tooth pins 3 are arranged at equal intervals along the circumferential direction of the outer cylinder 2. The first external teeth 14 a of the first oscillating gear 14 and the second external teeth 16 a of the second oscillating gear 16 are engaged with these internal tooth pins 3.

  The carrier 4 is accommodated in the outer cylinder 2 in a state of being arranged coaxially with the outer cylinder 2. The carrier 4 rotates relative to the outer cylinder 2 around the same axis. Specifically, the carrier 4 is arranged on the radially inner side of the outer cylinder 2, and in this state, the carrier 4 can be rotated relative to the outer cylinder 2 by a pair of main bearings 6 provided to be separated from each other in the axial direction. It is supported by.

  The carrier 4 includes a base portion having a substrate portion 4a and a plurality of (for example, three) shaft portions 4c, and an end plate portion 4b.

  The substrate portion 4a is disposed in the vicinity of one end portion in the axial direction in the outer cylinder 2. A circular through hole 4d is provided in the central portion in the radial direction of the substrate portion 4a. Around the through hole 4d, a plurality of (for example, three) crankshaft mounting holes 4e (hereinafter simply referred to as mounting holes 4e) are provided at equal intervals in the circumferential direction.

  The end plate portion 4b is provided to be spaced apart from the substrate portion 4a in the axial direction, and is disposed in the vicinity of the other end portion in the axial direction in the outer cylinder 2. A through hole 4f is provided at the radial center of the end plate portion 4b. Around the through hole 4f, a plurality of (for example, three) crankshaft mounting holes 4g (hereinafter simply referred to as mounting holes 4g) are provided at positions corresponding to the plurality of mounting holes 4e of the substrate portion 4a. In the outer cylinder 2, a closed space surrounded by both inner surfaces of the end plate portion 4 b and the substrate portion 4 a facing each other and the inner peripheral surface of the outer cylinder 2 is formed.

  The three shaft portions 4c are provided integrally with the substrate portion 4a, and linearly extend from one main surface (inner surface) of the substrate portion 4a toward the end plate portion 4b. The three shaft portions 4c are arranged at equal intervals in the circumferential direction (see FIG. 2). Each shaft portion 4c is fastened to the end plate portion 4b by a bolt 4h (see FIG. 1). Thereby, the board | substrate part 4a, the shaft part 4c, and the end plate part 4b are integrated.

  The input shaft 8 functions as an input unit to which a driving force of a driving motor (not shown) is input. The input shaft 8 is inserted into the through hole 4f of the end plate portion 4b and the through hole 4d of the substrate portion 4a. The input shaft 8 is arranged such that its axis coincides with the axes of the outer cylinder 2 and the carrier 4 and rotates around the axis. An input gear 8 a is provided on the outer peripheral surface of the distal end portion of the input shaft 8.

  The three crankshafts 10 are arranged at equal intervals around the input shaft 8 in the outer cylinder 2 (see FIG. 2). Each crankshaft 10 is supported by a pair of crank bearings 12a and 12b so as to be rotatable about the axis with respect to the carrier 4 (see FIG. 1). Specifically, a first crank bearing 12a is attached to a portion on the inside in the axial direction by a predetermined length from one axial end of each crankshaft 10, and the first crank bearing 12a is attached to the mounting hole 4e of the base plate portion 4a. It is attached to. On the other hand, a second crank bearing 12b is attached to the other axial end of each crankshaft 10, and this second crank bearing 12b is attached to the attachment hole 4g of the end plate portion 4b. Thereby, the crankshaft 10 is rotatably supported by the board | substrate part 4a and the end plate part 4b.

  Each crankshaft 10 has a shaft body 12c and eccentric portions 10a and 10b formed integrally with the shaft body 12c. The 1st eccentric part 10a and the 2nd eccentric part 10b are arrange | positioned along with the axial direction between the parts supported by both crank bearings 12a and 12b. Each of the first eccentric portion 10a and the second eccentric portion 10b has a columnar shape, and both of the first eccentric portion 10a and the second eccentric portion 10b protrude radially outward from the shaft body 12c in a state of being eccentric with respect to the shaft center of the shaft body 12c. The first eccentric portion 10a and the second eccentric portion 10b are each eccentric from the shaft center by a predetermined eccentric amount, and are disposed so as to have a phase difference of a predetermined angle.

  A fitted portion 10c to which the transmission gear 20 is attached is provided at one end portion of the crankshaft 10, that is, a portion on the axially outer side of a portion attached in the attachment hole 4e of the substrate portion 4a.

  The first oscillating gear 14 is disposed in the closed space in the outer cylinder 2 and is attached to the first eccentric portion 10a of each crankshaft 10 via a first roller bearing 18a. When each crankshaft 10 rotates and the first eccentric portion 10a rotates eccentrically, the first swing gear 14 swings and rotates while meshing with the internal tooth pin 3 in conjunction with the eccentric rotation.

  The first oscillating gear 14 has a size slightly smaller than the inner diameter of the outer cylinder 2. The first swing gear 14 includes a first external tooth 14a, a central through hole 14b, a plurality (for example, three) of first eccentric portion insertion holes 14c, and a plurality (for example, three) of shaft portion insertion holes 14d. And have. The first external teeth 14 a have a wave shape that is smoothly continuous over the entire circumferential direction of the oscillating gear 14.

  The central through hole 14 b is provided in the central portion in the radial direction of the first oscillating gear 14. The input shaft 8 is inserted into the central through hole 14b with play.

  The three first eccentric portion insertion holes 14c are provided at equal intervals in the circumferential direction around the central through hole 14b in the first swing gear 14. The first eccentric portions 10a of the respective crankshafts 10 are inserted into the first eccentric portion insertion holes 14c with the first roller bearings 18a interposed therebetween.

  The three shaft portion insertion holes 14d are provided at equal intervals in the circumferential direction around the central portion through hole 14b in the first swing gear 14. Each shaft portion insertion hole 14d is disposed at a position between the three first eccentric portion insertion holes 14c in the circumferential direction. The corresponding shaft portion 4c is inserted into each shaft portion insertion hole 14d with play.

  The second oscillating gear 16 is disposed in the closed space in the outer cylinder 2 and is attached to the second eccentric portion 10b of each crankshaft 10 via a second roller bearing 18b. The first oscillating gear 14 and the second oscillating gear 16 are provided side by side in the axial direction corresponding to the arrangement of the first eccentric portion 10a and the second eccentric portion 10b. When each crankshaft 10 rotates and the second eccentric portion 10b rotates eccentrically, the second swinging gear 16 swings and rotates while meshing with the internal tooth pin 3 in conjunction with the eccentric rotation.

  The second oscillating gear 16 has a size slightly smaller than the inner diameter of the outer cylinder 2 and has the same configuration as the first oscillating gear 14. That is, the second oscillating gear 16 includes a second external tooth 16a, a central through hole 16b, a plurality of (for example, three) second eccentric portion insertion holes 16c, and a plurality of (for example, three) shaft portion insertion holes 16d. Have. These have the same structure as the first external teeth 14a, the central through hole 14b, the plurality of first eccentric portion insertion holes 14c, and the plurality of shaft portion insertion holes 14d of the first swing gear 14. The second eccentric portion 10b of the crankshaft 10 is inserted into each second eccentric portion insertion hole 16c with the second roller bearing 18b interposed therebetween.

  Each transmission gear 20 transmits the rotation of the input gear 8a to the corresponding crankshaft 10. Each transmission gear 20 is externally fitted to a fitted portion 10 c provided at one end of the corresponding shaft body 12 c of the crankshaft 10. Each transmission gear 20 rotates integrally with the crankshaft 10 about the same axis as the rotation axis of the crankshaft 10. Each transmission gear 20 has external teeth 20a that mesh with the input gear 8a.

Here, the material which comprises the outer cylinder 2 and the rocking gears 14 and 16 which concern on a reference example is demonstrated.

  The outer cylinder 2 is made of a material having a larger linear expansion coefficient than the material of the first oscillating gear 14 and the second oscillating gear 16. Specifically, the outer cylinder 2 is made of an aluminum alloy, and the linear expansion coefficient of the material constituting the outer cylinder 2 is 20.0 to 23.5 μ / K. On the other hand, the rocking gears 14 and 16 are made of an iron-based material. For example, the oscillating gears 14 and 16 are made of steel having a carbon content of 0.7 to 1.0% (made of high carbon steel), or made of steel having a carbon content of 0.2% or less (made of low carbon steel). In this case, the linear expansion coefficient of the material constituting the rocking gears 14 and 16 is 10.8 to 11.0 μ / K, or 11.6 to 11.7 μ / K. Further, when these iron-based materials are hardened by hardening, the linear expansion coefficient is 13.6 μ / K when the carbon content is 0.2% or less, and the carbon content is 0.7 to 1.0%. Further, the linear expansion coefficient is 12.0 to 12.5 μ / K. The internal tooth pin 3 may also be formed of the same material as the rocking gears 14 and 16.

  As described above, in the gear device 1 of the present embodiment, the linear expansion coefficient of the material constituting the oscillating gears 14 and 16 is smaller than the linear expansion coefficient of the material constituting the outer cylinder 2. Therefore, when the outer cylinder 2, the carrier 4, and the oscillating gears 14 and 16 are heated when the gear device 1 is used, the outer cylinder 2 expands more than the oscillating gears 14 and 16. For this reason, a gap between the inner tooth pin 3 of the outer cylinder 2 and the outer teeth 14a and 16a of the swing gears 14 and 16, that is, between the inner peripheral surface of the outer cylinder 2 and the swing gears 14 and 16 is provided. The gap does not become narrower than before use. Therefore, even if the oscillating gears 14 and 16 are heated and expanded, it is possible to suppress an increase in the surface pressure of the tooth surfaces of the oscillating gears 14 and 16, and the life of the oscillating gears 14 and 16 can be reduced. Shortening can be suppressed.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the two swing gears 14 and 16 are provided. However, the present invention is not limited to this. For example, a configuration in which one oscillating gear is provided or a configuration in which three or more oscillating gears are provided may be employed.

  In the above embodiment, the input shaft 8 is disposed at the center of the carrier 4 and the plurality of crankshafts 10 are disposed around the input shaft 8. However, the present invention is not limited to this. For example, a center crank type in which the crankshaft 10 is disposed at the center of the carrier 4 may be employed. In this case, as long as the input shaft 8 is provided so as to mesh with the transmission gear 20 attached to the crankshaft 10, the input shaft 8 may be disposed at any position.

In the said embodiment, the case where the outer cylinder 2 as a reference example was made from aluminum alloy was illustrated . In contrast, in the embodiment, both the outer tube 2 and the oscillating gears 14 and 16 that are composed of a ferrous material. However, even in this case, the outer cylinder 2 needs to be made of a material having a linear expansion coefficient larger than that of the rocking gears 14 and 16. That is , if the outer cylinder 2 is made of steel (made of low carbon steel) having a carbon content of 0.2% or less and is hardened by hardening, the linear expansion coefficient is 13.6 μ / K. In this case, the oscillating gears 14 and 16 can be made of steel (made of high carbon steel) having a carbon content of 0.7 to 1.0%. In this case, the oscillating gears 14 and 16 are configured. When the material to be hardened is hardened and cured, the linear expansion coefficient is 12.3 to 12.4 μ / K. In this case, the internal tooth pin 3 may be formed of the same material as the rocking gears 14 and 16.

DESCRIPTION OF SYMBOLS 1 Eccentric oscillation gear apparatus 2 Outer cylinder 3 Internal tooth pin 4 Carrier 6 Main bearing 10 Crankshaft 10a 1st eccentric part 10b 2nd eccentric part 12a 1st crank bearing 12b 2nd crank bearing 12c Shaft body 14 1st oscillation Gear 14a External tooth 16 Second swing gear 16a External tooth

Claims (1)

A gear device that transmits a driving force by converting a rotational speed at a predetermined rotational speed ratio between a first member and a second member,
An eccentric part,
An oscillating gear that is made of an iron-based material having a carbon content of 0.7 to 1.0%, has an insertion hole into which the eccentric portion is inserted, and has a tooth portion;
A first cylindrical portion configured to be attachable to one of the first member and the second member;
A second cylindrical portion configured to be attachable to the other of the first member and the second member,
The first tube portion is made of an iron-based material having a linear expansion coefficient larger than that of the rocking gear and having a carbon content of 0.2% or less, and meshes with the teeth of the rocking gear. Have internal teeth,
The second cylinder part is disposed on the radially inner side of the first cylinder part in a state of holding the swing gear,
An eccentric oscillating gear device in which the first cylinder part and the second cylinder part are concentrically rotatable relative to each other by the oscillation of the oscillation gear accompanying the rotation of the eccentric part.

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