JP2006144888A - Eccentrically swing type gear device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eccentrically swing type gear device (speed reducer) increased in allowable transmission torque and protecting an oil seal. <P>SOLUTION: This eccentrically swing type gear device comprises a case 37, a pinion 33, a crank pin 31, and a support block 13. A transmission mechanism on a forward stage formed of gears 41 and 43 meshed with each other is positioned at one end of the support block, and a flange part 13c extending near the outer diameter of the case is formed on the outer periphery of the one end end face thereof. A through tap 13a for tightening a mating member 1 is formed in the flange part at a position near the radial outer side thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an eccentric oscillating gear device that is used by being fastened to a counterpart member such as an industrial robot, and more particularly to an eccentric oscillating type that can improve transmission torque with the counterpart member and achieve downsizing. The present invention relates to a gear device.

  Conventionally, in an industrial robot or the like, a motor having a high speed rotation and low torque is generally used as a high torque power source by interposing an eccentric oscillating gear device in a power transmission path between the motor and the robot. Yes.

In such a gear device, a bolt is used for fastening with a counterpart member (robot arm). The allowable transmission torque T in this case can be expressed by the following equation (1).
T = F × (D / 2) × μ × n (1)
Here, F: bolt tightening force, D: bolt mounting PCD (pitch circle diameter), μ: friction coefficient (μ = 0.15 (when oil adheres to the fastening surface), μ = 0.2 (fastening surface When degreasing))), n: number of bolts.

In order to increase the transmission torque between the gear device and the counterpart member,
A. Increase bolt size and increase bolt tightening force F.
I. Increase bolt PCD (D: pitch circle diameter),
C. Increase the number of bolts n,
D. Increasing the coefficient of friction μ in combination with other joining means (for example, knurling, pin combination, adhesive application, etc.)
Such measures can be considered. (Refer to the prior art in Patent Document 1)
JP 2000-154849 A

  However, these measures are based on the premise that basically the size of the other parts of the eccentric oscillating gear device is not changed or the parts are enlarged or reduced at a constant ratio without changing the structure at all.

  Therefore, in the case of (a), it is necessary to increase the shaft length in order to secure the depth of the fastening tap formed on the shaft, and the total weight of the gear device increases as the shaft length increases.

  In the case of A, since the structure of the gear device is not changed, it is necessary to increase the outer diameter size and the size of each part accompanying the increase in the bolt PCD, which increases the size of the gear device and leads to an increase in weight. Absent.

  In the case of c, the same problem as in the above a occurs. Moreover, in the case of said (a)-(c), it has the problem that a friction coefficient changes with the state of a fastening surface.

  Further, in the case of (d), when knurling is performed, if the knurling process is performed on the portion that also serves as the seal surface of the shaft, the conventional method of sealing using an O-ring has a recess formed by a protrusion. Oil leaks out. In addition, in order to transmit torque using a pin, in order to prevent chips generated during machining of the fastening surface and the mating member from entering into the gear device, the gear device must be masked. It becomes necessary and extra work increases. In addition, since the adhesive strength due to the adhesive greatly depends on the cleanliness of the fastening surface, a sufficient degreasing work is required, which takes time and effort, and the gear device and the mating member are fixed together. There are significant difficulties in disassembling.

  The inventor presupposes the above-mentioned prior art, that is, basically does not change the size of other parts of the eccentric oscillating gear device, or does not change the structure at all, and enlarges or reduces each part at a constant ratio. Regardless of this, the present invention has been conceived by focusing on the fact that an eccentric oscillating gear device having a large transmission torque can be obtained mainly by changing the dimensions of a specific portion (shaft) while maintaining the basic structure of the gear device. It is a thing.

  In the present invention, an inner tooth is provided on the inner periphery, the case rotates around the central axis, an outer tooth meshing with the inner tooth is provided on the outer periphery, and a plurality of through holes are disposed in the inner peripheral direction. A pinion that engages with the case and can move eccentrically, a plurality of crank pins that are inserted into the through holes of the pinion and take out the rotation of the pinion, and the crank pin is rotatably supported, and the case A transmission block provided on the crank pin and meshed with the input gear, the input gear disposed on the central axis of the case. Is located at one end of the support block, and a flange portion extending to the vicinity of the outer diameter of the case is formed on the outer periphery of the end surface on the one end portion side of the support block. Eccentrically oscillating gear device, wherein a through tapped for fastening the mating member on the side near the position is provided is provided.

  In this eccentric oscillating gear device, it is preferable that a recess is formed at one end in the axial direction of the support block, and the transmission mechanism of the previous stage is housed in the recess of the support block.

  In the present invention, a flange portion extending to the vicinity of the outer diameter of the case is formed on the outer periphery of the support block, and a through tap for fastening the mating member is provided at a position near the outer side in the radial direction of the flange portion. PCD (pitch circle diameter) can be increased, and the allowable transmission torque of the gear unit (reduction gear) can be improved.

  Moreover, in this invention, since the flange part is enlarged, the flat surface which contact | connects an other party member can be ensured, and a sealing performance can be improved.

  Furthermore, in the present invention, since the flange portion is enlarged, the gear attached to the crankpin can be made larger than before, and the front reduction ratio can be set larger, so that the total reduction ratio can be increased.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a part of an embodiment in which a gear device 4 according to the present invention is provided at a joint portion that pivotally attaches two arms 1 and 2 of an industrial robot. The cross section is taken along the line -I.

  The gear device 4 is an eccentric oscillating speed reducer, and the support block 13 of the eccentric oscillating speed reducer is fastened to one arm 1 and the case 37 side is connected to the other arm 2. . In this embodiment, the drive motor 3 is an electric servo motor, and the gear device 4 connected to the servo motor 3 has a first stage (front stage) of a spur gear reduction mechanism and a second stage (rear stage) of an eccentric swing type. It is a two-stage reduction mechanism for a gear reducer.

  First, the structure of the eccentric oscillating gear reducer will be described. The support block 13 includes a disc-like portion 17, a columnar portion 21 projecting from the disc-like portion 17, and an end disc 25, and is rotatable around the rotation axis of the case 37.

  A bearing mounting hole 17b having a predetermined depth is formed between adjacent columnar portions 21 on the surface of the disk-shaped portion 17, and a recess is formed on the back surface of the end disk 17 (the left end surface of the support block 13 in FIG. 1). Yes. Further, a central hole 21 a into which the input rotation shaft 11 is inserted is formed in the central portion of the columnar portion 21. The input rotation shaft 11 is formed integrally with the output shaft of the servo motor 3.

  Further, as shown on the right side of FIG. 1, an end disk 25 forming a part of the support block 13 is integrally coupled to the columnar part 21 of the disk-like part 17 by a pin 26, and the end disk 25 is The plate-like portion 17 is fixed to the columnar portion 21 with bolts 24. The screw hole 21 e is a fastening hole for the bolt 24 and is formed in the columnar portion 21.

  The end disk 25 is provided with a pin hole 25d corresponding to the pin hole 21b of the columnar part 21, and a bolt through hole 25c corresponding to the screw hole 21e. A bearing mounting hole 25b is formed corresponding to the hole 17b. Roller bearings 27 and 29 are mounted in the bearing mounting holes 17b and 25b, respectively, and a crank pin 31 for taking out the rotational motion of the pinion 33 is supported between the bearings 27 and 29 so as to be rotatable at both ends. The crank pin 31 has two crank portions 31a and 31b arranged eccentrically with respect to the rotation axis thereof, and a pinion 33 is fitted to the crank portions 31a and 31b.

  The pinion 33 has a tooth-shaped outer tooth having an equidistant curve to a pericycloidal curve on the outer peripheral surface, and includes a through hole 33 b that engages with a crank portion 31 a or 31 b of the crankpin 31 via a bearing 35.

  In this embodiment, ball bearings 36a and 36b are mounted on the outer peripheral portions of the disc-like portion 17 and the end disc 25 of the support block 13, and the case 37 is supported so as to be rotatable around the central axis a. The case 37 is connected to the other arm 2 by a bolt 7, and the number of internal teeth slightly larger than the number of external teeth formed on the outer periphery of the pinion 33 is formed on the inner peripheral surface thereof. When the center axis of the crank portions 31a and 31b revolves with respect to the rotation axis of the crankpin 31 by the rotation of the crankpin 31, the two pinions 33 are eccentrically revolved and the external teeth are internal gears of the case 37. Engage with.

  In the present embodiment, a first external gear 41 as an input gear is integrally formed at the left end of the input rotation shaft (servo motor output shaft) 11 disposed on the central axis a of the case 37, or is stopped. The second external gear 43 as a transmission gear having a larger number of teeth than the first external gear 41 is fixed to the left end portion of the crankpin 31 supported at both ends, and both the gears 41 and 43 are attached. The front transmission mechanism is configured by meshing, and the front transmission mechanism is housed in the recess of the support block 13 described above.

  In this embodiment, the output shaft of the servo motor 3 and the input rotary shaft 11 are integrated, and the first external gear 41 fixed to the input rotary shaft 11 is supported by the second external gear 43. The bearing for the input rotary shaft 11 is omitted. An oil seal 49 is provided outside the bearing 36 a that rotatably supports the case 37 described above to prevent leakage of lubricating oil from the gear unit 4.

  The rotation of the output shaft of the servo motor 3 (that is, the input rotation shaft 11 of the gear unit) is rotated by the teeth of the two gears 41 and 43 to the second external gear 43 engaged therewith through the first external gear 41 fixed to the input rotation shaft 11. Decelerated (first stage deceleration) according to the number ratio and transmitted. The crank portion 31a of the crankpin 31 supported at both ends rotatably by the support block 13 by the rotation of the second external gear 43 causes a revolving motion, and the pinion 33 engages with the crank portion 31a through the bearing 35 through the through hole 33b. Therefore, the eccentric revolving motion is caused by the revolving motion of the crank portion 31a. At this time, the plurality of crank pins 31 function so that only the rotational motion component of the revolving motion component and the rotational motion component of the pinion 33 is extracted to the case 37. Accordingly, the external teeth 33a formed on the outer periphery of the pinion 33 by the eccentric revolving motion of the pinion 33 engage with the internal gear formed on the inner periphery of the case 37, and the case 37 is decelerated and rotated (second-stage deceleration).

  In the present invention, the flange portion 13c of the support block 13 is enlarged radially beyond the bearings 36a and 36b beyond the bearings 36a and 36b, as shown in FIG. A fixing tap 13a is provided. The arm fixing tap 13a is a so-called through tap. The bolt 5 is inserted into the arm fixing tap 13a in the axial direction through the bolt insertion hole 1a drilled in the arm 1 from the outside of the arm 1, and the gear device (eccentric rocking gear device) 4 of the present invention is attached to the arm 1. Conclude. Note that the bolt 5 does not penetrate beyond the thickness of the flange portion 13c. Since the flange portion 13c is thus increased, the PCD (pitch circle diameter) of the bolt 5 can be increased, and the allowable transmission torque of the gear device (reduction gear) can be improved. Further, even when the present invention is used for an industrial robot for performing welding work, it is possible to prevent chips and sparks from damaging the oil seal 49. Furthermore, since the arm fixing tap 13a is provided at the radially outer position of the oil seal 49, oil leakage does not occur even as a so-called through tap, so the axial length of the reduction gear can be shortened.

  FIG. 2 is an end view of the state in which the robot arm 1 is removed from the gear device (eccentric oscillating gear speed reducer) 4 according to the present invention, and the gear device 4 described above is attached to the robot arm 1 with bolts 5. The arrangement state of the tap 13a for this is shown.

  In FIG. 2, the taps 13a do not exist at the outer positions of the three second external gears, and a flat surface 13d in contact with the mating member 1 can be secured, and the sealing performance can be improved. Further, according to the present invention, the PCD (pitch circle diameter) of the bolt can be increased, and the allowable transmission torque of the gear device (reduction gear) can be improved.

  With this configuration as described above, in the present invention, the bolt 5 is inserted into the arm fixing tap 13a from the left side of the arm 1 through the hole 1a, and the gear device (reduction gear) 4 according to the present invention is connected to the arm 1 by this bolt 5. Used by fixing to.

It is sectional drawing of one Example of the gear apparatus which concerns on this invention, and is made into the cross section along the II line | wire of FIG. It is a figure which shows the end surface in the state which removed the gear apparatus which concerns on this invention from the arm of the robot.

Explanation of symbols

1 Arm 2 Arm 3 Servo Motor 4 Gear Device (Eccentric Oscillation Reducer)
5 Arm fixing bolt 11 Input rotating shaft 13 Support block 13a Through tap 13c Flange 31 Crank pin 37 Case 41 Input gear 43 Transmission gear

Claims (2)

  A case provided with inner teeth on the inner periphery and rotating around the central axis, and outer teeth engaging with the inner teeth on the outer periphery, and a plurality of through-holes disposed in the inner periphery direction. A pinion that can move eccentrically, a plurality of crank pins that are inserted into the through holes of the pinion and take out the rotational movement of the pinion, and rotatably support the crank pin around the central axis of the case A transmission block provided on the central axis of the case and a transmission gear provided on the crank pin and meshing with the input gear. A flange portion is formed on the outer periphery of the end surface on the one end portion side of the support block, and is extended to the vicinity of the outer diameter of the case. Eccentrically oscillating gear device, wherein a through tapped for fastening the wood is provided.   2. The eccentric oscillating gear device according to claim 1, wherein a concave portion is formed at one end portion in the axial direction of the support block, and the front speed change mechanism is housed in the concave portion of the support block.

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