JP5466739B2 - 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. A swing gear having an insertion hole into which the eccentric portion is inserted and having a tooth portion, an outer cylinder configured to be attachable to one of the first member and the second member, and the first And a carrier configured to be attachable to the other of the second member and the second member. The outer cylinder has inner teeth that mesh with the teeth of the swing gear, and the carrier is disposed radially inward of the outer cylinder with the swing gear held, The carrier and the carrier can be concentrically rotated relative to each other by the swinging of the swinging gear accompanying the rotation of the eccentric part. In this eccentric oscillating gear device, the backlash angle is set to 2 to 3 minutes so that the backlash angle of the carrier with respect to the outer cylinder becomes approximately 1 minute due to thermal expansion of the oscillating gear in use. ing.

  Generally, when an eccentric oscillating gear device is used, the oscillating gear is hotter than the outer cylinder. For this reason, the clearance between the internal teeth disposed on the outer cylinder and the tooth portion of the swing gear tends to be narrower than before use. Therefore, if the backlash angle of the oscillating gear with respect to the outer cylinder is set to approximately 1 minute, as in a normal eccentric oscillating gear device, if the clearance (play) becomes narrow due to heat generated by the oscillating gear, This leads to an increase in the surface pressure of the tooth surface of the dynamic gear, and the fatigue strength is reduced. On the other hand, in the present invention, the backlash angle is set to 2 to 3 minutes. Therefore, when the eccentric gear device is operated and the swing gear is heated and expanded, The backlash angle can be approximately 1 minute. Therefore, since the backlash angle of the carrier with respect to the outer cylinder does not become excessive when in use, the stopping accuracy can be maintained as an eccentric oscillating gear device, and the surface pressure of the tooth surface of the oscillating gear is increased. It is possible to suppress the increase, and it is possible to suppress a reduction in the life of the oscillating gear.

  Here, the relative rotational speed between the outer cylinder and the carrier may be 80 rpm to 200 rpm.

  In this aspect, since the rotation speed is used in a high speed region of 80 rpm to 200 rpm, the temperature of the oscillating gear after the start of use is fast. Therefore, the time until the normal backlash angle (approximately 1 minute) is reached after the start of use is also short, and the warm-up operation time can be shortened or eliminated.

  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. (A) It is sectional drawing in the II-II line | wire of FIG. 1, (b) is the elements on larger scale of (a). It is a figure for demonstrating a backlash angle. It is a figure for demonstrating the change of the backlash angle accompanying the temperature change of an outer cylinder.

  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, or a revolving part of various machine tools. 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. Thereby, for example, relative rotation can be caused between the base of the robot (one counterpart member) and the swing drum (the other counterpart member).

  As shown in FIGS. 1 and 2, the gear device 1 includes an outer cylinder 2, a carrier 4, an input shaft 8, a plurality of (for example, three) crankshafts 10, a first swing gear 14, and a second The 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. The outer cylinder 2 is fastened to, for example, a robot base (not shown; first member). 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 outer cylinder 2 is provided with a flange portion. The flange portion is formed with an insertion hole 2c for inserting a fastener (bolt) for fixing to the base of the robot, for example.

  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 is fastened to, for example, a revolving drum (not shown; second member) of the robot. 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.

  A fastening hole 4i for fastening a fastener (bolt) (not shown) for fixing the carrier 4 to, for example, a rotating drum of the robot is formed in the substrate portion 4a.

  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. 2A). 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 includes a shaft main body 10c and eccentric portions 10a and 10b formed integrally with the shaft main body 10c. 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 10c in a state of being eccentric with respect to the shaft center of the shaft body 10c. 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 10d to which the transmission gear 20 is attached is provided at one end portion of the crankshaft 10, that is, a portion on the outer side in the axial direction 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 10d provided at one end of the corresponding shaft body 10c 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 backlash angle of the carrier 4 in the gear device 1 according to the present embodiment will be described. The backlash angle is an angle at which when the torque is applied to the carrier 4 while the input shaft is fixed, the carrier 4 rotates around the axis while the torque is zero. That is, since there is a gap between the external teeth 14a and 16a of the swing gears 14 and 16 in the carrier 4 and the internal tooth pin 3 in the outer cylinder 2, as shown in FIG. When the torque is applied to the outer teeth 14a and 16a, the outer teeth 14a and 16a are slightly rotated with the torque zero until the outer teeth 14a and 16a mesh with the inner tooth pin 3. This rotation angle is an angle corresponding to the size of the gap between the external teeth 14a, 16a and the internal tooth pin 3. As shown in FIG. 3, when the external teeth 14 a and 16 a are engaged with the internal tooth pin 3, the torsion angle of the carrier 4 becomes a magnitude corresponding to the magnitude of the applied torque. As described above, the carrier 4 can be rotated while the torque is zero at a backlash angle corresponding to the size of the gap, and the magnitude of the backlash angle affects the positioning accuracy (stopping accuracy) of the robot. Therefore, in general, the shapes of the outer cylinder and the swing gear are set so that the backlash angle is about 1 minute (1 / 60th of a degree).

  On the other hand, in the gear device 1 of the present embodiment, the backlash angle is set to 2 to 3 minutes before use. That is, since the outer cylinder 2 radiates heat to the outside air or radiates heat to the mating member (for example, the base of the robot), the amount of thermal expansion is smaller than that of the rocking gears 14 and 16 and the internal tooth pin 3. For this reason, when the gear device 1 is operated, the clearance (clearance) between the external teeth 14a, 16a of the rocking gears 14, 16 and the internal tooth pin 3 tends to be narrowed. Thereby, in the gear apparatus 1 of this embodiment, the backlash angle is set to approximately 1 minute due to the temperature rise during use. For example, by reducing the outer diameter of the internal tooth pin 3 as compared with the conventional one, a clearance corresponding to the clearance reduction due to heat generation can be added in advance.

  FIG. 4 shows a change from the state before use of the backlash angle due to heat generation during use. At the time of use, the temperature of the outer cylinder 2 rises to about 70 to 80 ° C. Therefore, if the backlash angle is 2 minutes before use (for example, 20 ° C.), the backlash angle is less than 1 minute (about 0.6 minutes) at 70 ° C. Further, if the backlash angle is 3 minutes before use, the backlash angle is about 1.2 minutes at 70 ° C. Therefore, if the backlash angle before use is 2 to 3 minutes, the backlash angle during use is about 1 minute. In particular, in the present embodiment, since the gear device is used at 80 rpm to 200 rpm, it does not take much time to reach this temperature, and is rarely used in a state with a large backlash. In FIG. 4, the data when the backlash angle is 3 minutes before use is an estimated value.

  As in Comparative Example 1 shown in FIG. 4, when the backlash angle is 1 minute in the state before use, the backlash angle does not decrease even when the temperature rises at 60 ° C. or higher, and it remains stopped. This is presumed to represent a state in which the gap has already disappeared around 60 ° C. On the other hand, Comparative Example 2 shows a case where the backlash angle is 6 minutes before use, but in Comparative Example 2, the backlash angle is approximately 4 minutes even during use when the temperature of the outer cylinder is increased. The positioning accuracy (stopping accuracy) of the robot will be poor.

  As described above, in the gear device 1 according to the present embodiment, the backlash angle is set to 2 to 3 minutes, so that when the gear device 1 is operated, the oscillating gears 14 and 16 are heated to expand. Then, the backlash angle of the carrier 4 with respect to the outer cylinder 2 can be set to about 1 minute. Accordingly, since the backlash angle of the carrier 4 with respect to the outer cylinder 2 does not become excessive during use, the stopping accuracy of the eccentric oscillating gear device 1 can be maintained, and the oscillating gears 14 and 16 An increase in the surface pressure of the tooth surface can be suppressed, and a reduction in the life of the oscillating gears 14 and 16 can be suppressed. That is, it is possible to optimize the backlash angle during actual use.

  Moreover, in this embodiment, the relative rotation speed between the outer cylinder 2 and the carrier 4 is 80 rpm to 200 rpm. In this embodiment, since the rotation speed is used in a high speed region of 80 rpm to 200 rpm, the temperature of the rocking gears 14 and 16 after the start of use is fast. Therefore, the time until the normal backlash angle (approximately 1 minute) is reached after the start of use is also short, and the warm-up operation time can be shortened or eliminated.

  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 above embodiment, the outer cylinder 2 is coupled to the base of the robot and the carrier 4 is coupled to the turning cylinder of the robot, and the carrier 4 rotates with respect to the outer cylinder 2. Instead, the carrier 4 may be coupled to the base of the robot and the outer cylinder 2 may be coupled to the revolving barrel of the robot so that the outer cylinder 2 rotates with respect to the carrier 4.

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

Claims (2)

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 having an insertion hole into which the eccentric part is inserted and having a tooth part;
An outer cylinder configured to be attachable to one of the first member and the second member;
A carrier configured to be attachable to the other of the first member and the second member,
The outer cylinder has inner teeth that mesh with the teeth of the swing gear,
The carrier is disposed on the radially inner side of the outer cylinder while holding the swing gear,
The outer cylinder and the carrier are concentrically rotatable relative to each other by the swinging of the swinging gear accompanying the rotation of the eccentric part,
The eccentric oscillating gear device, wherein the backlash angle is set to 2 to 3 minutes so that the backlash angle of the carrier with respect to the outer cylinder becomes approximately 1 minute due to thermal expansion of the oscillating gear in use.   The eccentric oscillating gear device according to claim 1, wherein a relative rotational speed between the outer cylinder and the carrier is 80 rpm to 200 rpm.

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