JPS63109994A - Wrist mechanism for industrial robot - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a wrist mechanism for an industrial robot having a reducer in the wrist, and is particularly suitable for speeding up and assembling, adjusting and maintaining gear parts. Regarding the wrist mechanism.

[Conventional technology]

BACKGROUND OF THE INVENTION As industrial robots become more widespread in production sites, the objects that robots work on are becoming more diverse.

In order to deal with such complex work objects, industrial robots generally require a wrist mechanism that provides two or three degrees of freedom of movement so that the posture of the wrist in the space can be arbitrarily selected.

Conventionally, such a wrist mechanism includes actuators 81A and 81B arranged in a rear hollow chamber 80a of a robot arm 80, as shown in FIG.

The rotation of 81G is transmitted through reducers 82A and 82A, which are directly connected to each other.
After decelerating to a predetermined rotational speed via 82B and 82C,
The rotational power is provided by rotating shafts 83A and 83B inserted and supported within the robot arm 80.

83C respectively.

The rotational power transmitted to the rotating shaft 83A drives the outer casing 85 directly connected to the rotating shaft 83A to
It is rotated in the direction. Further, the rotational power transmitted to the rotating shaft 83B is transmitted to a bevel gear 89 connected to the inner casing 88 via a bevel gear 86 integrally provided at the tip of the rotating shaft 83B. The rotational power transmitted to the rotating shaft 83G is transmitted to the bevel gear 95 connected to the hand holder 93 via the bevel gears 90, 91, 92, and the hand holder is rotated in the direction of arrow β. The structure is such that the body 93 is driven to rotate in the direction of the arrow γ.

FIG. 4 shows a wrist mechanism disclosed in Japanese Unexamined Patent Publication No. 59-73297, in which the rotational power of a rotating shaft 101 housed in a robot arm is transferred to a pair of bevel gears 102A provided at its tip. , 102B, pulley timing belt mechanism 103. Harmonic Drive (registered trademark of Harmonic Drive System Co., Ltd.) is transmitted to the outer casing 105 via the reducer 104, causing the outer casing 105 to rotate. Inside the outer casing 105, the inner casing 106 has a bearing 107A.

It is rotatably supported by 107B. Further, the rotational power of the rotating shaft 108 housed in the axial center hollow part of the rotating shaft 11 is transmitted through a bevel gear 109A integrally provided at the tip thereof.
, a set of bevel gears 109 that mesh with the bevel gear 109A.
B, is transmitted via the pulley/timing belt mechanism 111 and harmonic drive reducer 112 to a pair of bevel gears 113A and 113B provided on the output side of the harmonic drive reducer 112, and integrally with the bevel gear 113B. The formed hand holding body 115 is configured to be rotated.

[Problem that the invention seeks to solve]

However, according to the above-mentioned former conventional technology, the load torque at the tip of the wrist is directly transmitted to the single rotating shaft of the bevel gear, so the diameters of the bevel gear and the rotating shaft need to be increased, resulting in a larger single wrist mechanism. This was a contributing factor. Furthermore, since the bevel gear is installed on the output side of the reducer, it is necessary to have high assembly accuracy and high processing accuracy. Further, as the outer casing 85 rotates in the α direction due to the rotation of the rotating shaft 83A, the inner casing 88 rotates in the β direction and the hand holder 93 rotates in the γ direction, so each rotation direction is simultaneously operated in a predetermined direction. In some cases, there is a problem in that it is necessary to widen the rotational speed range of the hand holding body 93.

Further, according to the latter conventional technology, the bevel gear 102A,
Since 102B, 109A, and 109B are arranged inside the outer casing 105, there is a problem in that assembly and adjustment are complicated. Furthermore, one set of bevel gears 113A, 1
Since the bevel gear 113B is installed on the output side of the harmonic drive reducer 112, there is a problem in that the play during assembly of the bevel gears 113A and 113B directly affects the accuracy of the entire wrist mechanism.

An object of the present invention is to enable transmission of torque from a drive means disposed on a robot arm to a reducer in a state substantially equal to the output shaft torque of the drive means, and to remove a bevel gear used in a power transmission path. This invention provides a wrist mechanism for an industrial robot that can be placed outside the casing.

Means for Solving Problem C] In order to achieve the above object, the wrist mechanism of the industrial robot according to the present invention has three first and third wrist mechanisms that are inserted into the robot arm and rotationally driven by a drive means. 2. and third
a rotating shaft, an outer casing fixed to the tip of the outermost first rotating shaft of the triple rotating shafts, and into which the second and third rotating shafts are inserted and supported, and the outer casing an inner casing rotatably supported around an axis orthogonal to the first rotation axis and driven in conjunction with the second rotation axis; a hand holder rotatably mounted; a hand holder rotatably supported by the outer casing at a position parallel to the second and third rotation axes and eccentric in the radial direction; a parallel shaft for the inner casing and a parallel shaft for the hand holder, which are each rotationally driven in conjunction with the shaft; and a parallel shaft for the inner casing that is rotatably supported by the outer casing at right angles to the parallel shaft for the inner casing, and provided within the outer casing. An inner casing drive shaft that drives the inner casing via a speed reducer, and a series of parallel shafts that are perpendicular to the hand holder parallel shaft and coaxial with the inner casing drive shaft. The hand holder drive shaft is driven via a bevel gear.

[Effect]

According to the above configuration, the power from the driving means is transmitted to the first and second
When the signal is transmitted to the third rotating shaft, the outer casing rotates integrally with the first rotating shaft, and the inner casing rotates around an axis perpendicular to the first rotating shaft. At the same time, the parallel shaft for the hand holder and the hand holder drive shaft rotate, and the speed is reduced by the speed reducer, so that the hand holder rotates around an axis parallel to the first rotation axis.

(Example) Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

1 and 2 relate to an embodiment of the present invention, in which an industrial robot 1 includes a traveling body 2, a base 3, an upright arm 5,
It is equipped with a wrist mechanism 8 provided with a robot arm 6,
The traveling body 2 is mounted on a base 3 so as to be travelable. The upright arm 5 is upright and swingably pivotally connected to the upper end of the traveling body 2, and the robot arm 6 is pivotally mounted to the upper end of the upright arm 5 so as to protrude horizontally. .

At the base end 6a of the robot arm (hereinafter simply referred to as arm) 6, actuators IOA and IO, which are driving means, are provided.
B, an IOC is arranged, and in the arm 6 there is an outermost first rotating shaft 11A and a second rotating shaft accommodated in a hollow part formed at the axis of the first rotating shaft 11A. The shaft 11B and the outermost third rotary shaft 11C housed in a hollow portion formed at the axis of the second rotary shaft 11B are rotatably supported. and the first, second and third
The rotating shafts 11A, IIB, and IIC are connected to actuators 10A, IOB, and IIC through reduction gears (not shown), respectively.
Power is transmitted from the OC.

The outer casing 12 is fixed to the tip of the first rotating shaft 11A, and the outer casing 12 is attached to the bearing 1 provided at the tip 6b of the arm 6.
It is rotatably supported by 3A and 13B. The toothed pulley 15 is formed into a hollow cylindrical shape, and is connected to the second rotating shaft 11.
The shaft portion 15a is rotatably supported by a bearing 16 provided in the hollow portion of the outer casing 12.

An inner casing parallel shaft 19 is arranged on the outer circumferential surface of the outer casing 12, parallel to the second rotating shaft 11B, eccentric, and rotatably supported by bearings 18A, 18B. A toothed pulley 20 is fixed to one end, a bevel gear 21 is fixed to the other end, and a hole 1 formed in the outer casing 12 is provided between the toothed pulleys 15 and 20.
A toothed belt 22 is wound around the belt 2a.

The bevel gear 21 meshes with a bevel gear 26 fixed to one end of an inner casing drive shaft 25 rotatably supported by a bearing 23 provided in the outer casing 12 in a direction orthogonal to the parallel axis 19.

The inner casing 3o is rotatably supported by the outer casing 12 by bearings 31A and 31B provided in the outer casing 12 and concentric with the drive shaft 25. A fixed side circular spline 32 of the harmonic drive reducer is fixed to the outer casing 12 , a wave generator 33 fixed to the drive shaft 25 , and an output side circular spline fixed to the inner casing 30 . In combination with 35, a reduction gear is constructed.

The toothed pulley 36 is fixed to the tip of the third rotating shaft 11c, and its shaft portion 36a is rotatably supported by a bearing 38 provided within the toothed pulley 15. Also, on the outer peripheral surface of the outer casing 12.

The bearing 39A is parallel to and eccentric to the third rotating shaft 11C.
, 39B is disposed, and a toothed pulley 41 is fixed to one end of the parallel shaft 40, and a bevel gear 42 is fixed to the other end of the parallel shaft 40. A toothed belt 43 is wound between the pulleys 36 and 41 through a hole 12b formed in the outer casing 12. The bevel gear 42 is connected to the outer casing 1 on the same axis as the drive shaft 25 in a direction orthogonal to the parallel shaft 40.
2 and is rotatably supported by a bearing 45. The bevel gear 48 is fixed to one end of a hand holder drive shaft 46 which is rotatably supported by a bearing 45. Drive shaft 4 located within inner casing 12
A bevel gear 49 is fixed to the other end of 6.

Inside the inner casing 12, a hand power transmission shaft 51 having a bevel gear 50 fixed to one end that meshes with the bevel gear 49 is rotatably supported by bearings 52A and 52B parallel to the axis of the inner casing 12.

The hand holder 53 is formed into a cylindrical shape with one end open, and its inner peripheral surface is rotatably supported by a bearing 55 provided on the outer peripheral surface of the inner casing 30. A fixed side circular spline 56 of the harmonic drive reducer is fixed to the tip of the inner casing 30, and a wave generator 58 fixed to the tip of the hand transmission shaft 51 and the inside of the hand holder 53 are connected to the circular spline 56, a wave generator 58 fixed to the tip of the hand transmission shaft 51, and a In combination with the fixed output side circular spline 59, a reduction gear is constructed.

In addition, in FIG. 1, 60 is a cover for covering the outer peripheral surface of the outer casing 12, and is detachably attached to the outer casing 12.

Next, the operation of the embodiment of the present invention will be explained.

The power from the actuator IOA is transmitted to the first rotating shaft 11A via the reducer, and this rotational torque causes the outer casing 12 fixed to the first rotating shaft 11A to rotate in the direction of the arrow α. Next, when power is transmitted from the actuator 10B to the second rotating shaft 11B via the reducer, the inner casing parallel shaft 19 is rotated by the toothed pulley 15, the toothed belt 22, and the toothed pulley 20.
Drive shaft 25 for the inner casing via bevel gears 21, 26
The rotational torque is transmitted to the wave generator 58 and the fixed side circular spline 32.
The inner casing 30 rotates in the direction of the arrow β with respect to the outer casing 12 via the output side circular spline 35.

When power is transmitted from the actuator IOC to the third rotating shaft 11C via the reducer, the toothed pulley 36. The parallel shaft 40 for the hand holder is rotated by the toothed belt 43 and the toothed pulley 41, and rotational torque is transmitted to the hand holder drive shaft 46 via the bevel gear 42, 48, and this rotation torque causes the bevel gear 49 to rotate. The hand transmission shaft 51 rotates through .50. The rotation of the hand transmission shaft 51 is decelerated by a harmonic drive reducer disposed at the tip of the inner casing 30 and transmitted to the hand holder 53.
The hand holding body 53 rotates in the direction of arrow γ.

As described above, according to this embodiment, in the power transmission path to the inner casing 30 and the hand holder 53, the power is transmitted at high speed and with small torque up to the input end of the harmonic drive reducer. , the toothed belt, the toothed pulley, and the bearings that support them can be made relatively small in terms of strength, and the wrist mechanism 8 can be made small and lightweight. Moreover, the influence of backlash of the bevel gears 21, 26, 42, 4B, 49.50 and the toothed belt 22.43 used during this time is reduced by the influence of the high reduction ratio of the harmonic drive reducer.

In addition, by providing the parallel shaft 19 for the inner casing and the parallel shaft 40 for the hand holder in the outer casing 12, the assembly and adjustment of the bevel gears 21, 26, 42.48 and the tension of the toothed belt 22.43 @ This can be easily done by removing the cover 6. Furthermore, β of the inner casing 30 due to the movement of the outer casing 12 in the α direction
The movement in this direction and the interference of the hand holding body 53 in the γ direction are caused by the high deceleration of the harmonic drive mechanism.

The influence can be reduced, and as a result, the speed of operation in the β and γ directions can be increased easily.

FIG. 3 shows another embodiment of the drive mechanism for the inner casing 30 and the hand holder 53, in which the toothed belt 22 is connected to the toothed pulley 15 of the second rotating shaft 11B and the toothed pulley 41 of the parallel shaft 40. A toothed belt 43 is wound around the toothed pulley 36 of the third rotating shaft 11C and the toothed pulley 20 of the parallel shaft 19. The other configurations are similar to those shown in FIG.

According to the embodiment shown in FIG. 3 above, the third rotating shaft 11C
Since the hand holding body 53 is driven by the second rotating shaft 11B having a larger diameter, when the length of the arm 6 is increased and the hand holding body 53 is rotated at high speed, that is, the second rotating shaft Even when the rotary shaft 11B is rotated at high speed, the second rotary shaft 11B has a higher natural frequency than the third rotary shaft 11c and will not be in a resonant state. Therefore, there is no possibility that the second rotating shaft 11B will interfere with other members. On the other hand, the third rotating shaft 11G drives the inner casing 30 whose rotation speed is relatively low, so its rotation speed is slow.
There will be no resonance.

〔Effect of the invention〕

As described above, according to the present invention, the component parts can be made small, so the single wrist mechanism can be made small.

And it can be made lightweight. Further, since the structural parts that require adjustment during assembly and maintenance are arranged on the outer peripheral surface of the outer casing, the structural parts can be easily adjusted by simply removing the cover. Further, by increasing the speed reduction of the harmonic drive reducer, interference between the rotating shafts can be suppressed to a small level, so that a wrist device suitable for high speed operation can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the wrist mechanism of an industrial robot according to the present invention, Fig. 2 is a side view of the industrial robot, and Fig. 3 shows another embodiment of the drive mechanism for the inner casing and hand holder. 4 and 5 are longitudinal sectional views of a wrist mechanism of an industrial robot according to a conventional example. 1...Industrial robot, 6...Robot arm. 8... Wrist mechanism, IOA, IOB, IOC... Actuator as driving means, IIA, IIB, and 11
C... 1st. second and third rotating shafts, 12... outer casing, 19... parallel shaft for inner casing, 25...
...Drive shaft for inner casing. 30... Inner casing, 40... Parallel shaft for hand holder, 42.48, 49.50... Bevel gear, 46.
...Hand holding body drive shaft, 53...Hand holding body.

Claims (1)

[Claims] Triple first, second, and third rotating shafts that are inserted into the robot arm and rotationally driven by the driving means, and the tip of the outermost first rotating shaft among the three rotating shafts. an outer casing which is fixed to the outer casing and into which the second and third rotating shafts are inserted and supported; an inner casing driven in conjunction with the rotating shaft of No. 2;
a hand holder rotatably attached to the tip of the inner casing via a speed reducer; A parallel shaft for the inner casing and a parallel shaft for the hand holder are supported and rotated in conjunction with the second and third rotating shafts, and the parallel shaft for the inner casing is orthogonal to the parallel shaft for the outer casing. an inner casing drive shaft that is rotatably supported and drives the inner casing via a speed reducer provided in the outer casing; and an inner casing drive shaft that is orthogonal to the hand holder parallel axis. and a hand holder drive shaft that drives the hand holder via a series of bevel gears on the same line as the hand holder.