JPS6044291A - Wrist device for industrial robot - Google Patents

Abstract

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

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in wrist devices for industrial robots.

[Technical background of the invention]

In industrial robots used for spot welding, which involves complex assembly work, it is necessary to be able to arbitrarily select the posture of the tool such as a spot welding gun or the hand member that grips or supports the workpiece in space. For,
Generally, the wrist device is provided with degrees of freedom of rotation around three mutually orthogonal axes.

First, we will introduce the conventional wrist device l for an industrial robot which is given three degrees of freedom and is driven by an actuator such as an electric motor or a fluid pressure motor.
This will be explained using figures.

Inside the casing 3 at the rear end of the arm 2, there are three anti-four motors μaX! such as electric motors or fluid pressure motors. b
,≠C are arranged, and each actuator≠a, I
Reducer for IbX≠C! 8,! bXj'c is directly connected,
The rotational speed of each actiny tag is decelerated to a speed approaching the operating speed required for hand member B, which will be described later. Inside the armco, three transmission shafts g&, zasu, and zac are concentrically connected to each of the reduction gears via a pair of spur gears 7.7, and one end protrudes from the armco. It is arranged like this. Of these, the outermost transmission shaft 1a is provided with a protruding casing holder for the wrist device, and this casing holder is connected to the actuator +
It is designed to be rotated in the α direction in FIG. 1 by the drive of a. A rotary shaft IO is rotatably arranged in the casing holder so as to be orthogonal to the transmission shaft ♂, and this rotary shaft 10 has an intermediate transmission shaft! rb
A bevel gear /Y meshing with a bevel gear // provided protrudingly is supported. Furthermore, the bevel gear 12 has a sleeve 1.
3 is fixed to the sleeve 13, and the sleeve 13 is rotated in the β direction in FIG. 1 by driving the actuator 4tb. The front end of the sleeve 13 is integrally provided with a small diameter portion /3 that protrudes to the outside through the front opening lt of the casing, and this small diameter portion is has a rotation axis of the hand member 7B. 1A is rotatably supported. This rotating shaft /A is disposed perpendicular to the rotating shaft 10, and the rotating shaft /J is connected to the rotating shaft via two pairs of mutually meshing bevel gears /7.1g and /9,X). It is connected to the innermost transmission shaft C. Therefore, the hand member t is rotated in the r direction in FIG. 1 by the drive of the actuator≠C.

Such a conventional industrial robot wrist device l has each actuator ≠8, ≠bXI1 . By driving c, the tool or workpiece (not shown) protruding from the hand member B can be moved arbitrarily.

[Problems with background technology]

However, in the wrist device of the conventional industrial robot mentioned above, a torque of about the same magnitude as the load moment applied to the hand member B acts on each transmission shaft and gears. Therefore, the diameter of each transmission shaft g becomes large. As a result, the arm λ becomes thick and heavy, and the case, bevel gears, etc. must be large and strong.
This is a factor that hinders the reduction in size and weight of the module, and the disadvantage is that positioning accuracy decreases due to pitch errors and paraclarity, which increase as the number of modules increases.

On the other hand, regarding the drive, for example, when rotating the wrist device l in the α direction of the casing, a bevel gear l disposed around the same axis as the axis of the arm, which is the axis of movement in the rotational direction α. /, 17 and bevel gear i meshing with these: x, i
Since the relative motion of g is derived, the swing of the hand member B in the β direction and the rotation in the r direction will be affected. Also, when shaking the hand member B in the β direction, the bevel gear 1
A relative movement occurs between the bevel gear 1 and the coaxial bevel gear 1, and the hand member 2 rotates in the r direction.

Such interference between the transmission shafts is caused by the bevel gears 1/12 and 1g, or the bevel gears /7 and 1g.

Furthermore, bevel gear /9 and:1. Since the rotation angle of O and the operating angle of the tip of the wrist, that is, the operating angle of the hand member A, are approximately equal, the size of the member cannot be ignored. There was a problem that the robot was difficult to operate.

[Purpose of the invention]

In view of the above-mentioned points, the present invention has been developed to provide an industrial device that is small and lightweight, can suppress as much as possible the deterioration of positioning accuracy caused by gear paraclarity, and can also ignore the interference of motion between degrees of freedom. The purpose is to provide a robot wrist device.

[Summary of the invention]

In a wrist device for an industrial robot that has three degrees of freedom and is driven by actuators provided in an arm at the base, each wrist device is driven by an independent actuator and is arranged so as to protrude concentrically from the arm. three transmission shafts, a wrist casing protruding from the outermost transmission shaft, and a wrist casing supported in front of the wrist casing so as to be rotatable about an axis perpendicular to the transmission shafts. a cylindrical shaft located in front of the cylindrical shaft, a high reduction ratio reducer that reduces and transmits the rotation of the intermediate transmission shaft to the cylindrical shaft, and a shaft center perpendicular to the cylindrical shaft located in front of the cylindrical shaft. The hand member is supported so as to be able to rotate about a center, and another reduction gear with a high reduction ratio transmits the rotation of the innermost transmission shaft to the hand member at a reduced speed. That is.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings.

Figure 2 shows the entirety of an industrial robot (R) to which the wrist device/A according to the present invention is applied. 3 is supported, and a wrist device/A is attached to the tip of the arm λ.
is installed protrudingly.

Inside the arm λ are three transmission shafts 1t+ of the wrist device/A.
, IbX♂C are arranged concentrically, and the outermost transmission shaft lra is connected to an actuator disposed in the casing 3, a reducer a, and a pair of mutually meshing spur gears 7. Connected via .7. Further, the intermediate transmission shaft ♂b and the innermost transmission shaft C are each connected to a corresponding actuator disposed within the casing 3.
It is connected to b1μC without going through a speed reducer.

Details of the wrist device/A are shown in FIGS. 3 to 5, particularly in FIG.

As shown in detail in FIG. 5, the hollow outermost transmission shaft fa is rotatably supported by a bearing J provided at the inner end of the hollow arm 2, and protrudes from the tip of the arm co. A flange J is provided around the end of the transmission shaft fa, and a concave wrist casing 2J is fixed to this flange by a threaded portion 2B. On the other hand, a hollow intermediate transmission shaft rb is rotatably supported by the bearings 27 provided at the inner ends of the two flanges, and the transmission shaft tb
The tip faces into the wrist casing Δ. A bevel gear U is fitted onto the tip of the transmission shaft ♂b. On the other hand, a sleeve 29 in a direction perpendicular to the axis of the transmission shaft r is fixed to the wrist casing 3 by a screw member 30, and a hollow shaft 32 is attached to the sleeve 29 via a bearing 3/. is rotatably supported. A bevel gear 3 that meshes with the bevel gear 28 is attached to the lower end of the hollow shaft 3.2.
3 is fitted, and a spur gear 31 is fixed to the pin 35 at the upper end. A bearing 3A is installed inside the bevel gear N.
The innermost transmission shaft ♂C is rotatably supported by the bearing 3O, and a bevel gear 37 is fitted to the tip of the transmission shaft J'e. On the other hand, the hollow shaft 3.2
A shaft 39 is supported inside via a bearing 3g, a bevel gear O meshing with the bevel gear 37 is fitted to the lower end of the shaft 39, and a spur gear tl is fitted to the upper end of the shaft 39 to engage the bevel gear 37. It is fixed by.

The upper and lower ends of the wrist casing 2J are respectively screwed with yuukomi board gen and pots that protrude forward from the wrist casing J, and the front ends of each cover plate IA3 and the hoko are respectively integrated with the wrist casing Δ. Front cover 〇, screw member I on the side
It is attached to A7, and a large gap is formed between both cover plates and the offset. Wrist casing J located between the wrist casing J and the upper front cover Q in FIG.
There is a bearing width and μ between a part of the lower front cover.
A cylindrical shaft 50 located in front of the wrist casing 2J is rotatably supported by these bearings ψg and μ9. Note that the bearing rig is held by a bearing presser 5. The axial center of the cylindrical shaft 50 is perpendicular to the axial center of the arm λ. This cylindrical shaft 5
0 has a cylindrical shaft S at approximately the same height as the sleeve unit 9.
A sleeve member is fixed by a screw member 30 so as to be coaxial with O, and a hollow shaft 3a is rotatably supported by the sleeve member via a bearing S3. At the upper end of this hollow shaft 3ti, there is a spur gear 5 that meshes with the spur gear 3I/. ; is firmly fixed to the bottle S6, and a bevel gear j7 is fitted to the lower end. A shaft 3g is disposed within the hollow shaft yt concentrically with the hollow shaft 51, and this shaft sg is connected to the hollow shaft 54. It is rotatably supported by bearings j9, θ, and 6/ provided on the cylindrical shaft 50 and the cover plate pot, respectively. A spur gear 62 that meshes with the spur gear lA/ is fixed to the upper end of the shaft sg by a pin 63, and a web generator similar to the harmonic drive mechanism A is fitted to the lower end. The outer circumferential surface 6t of the web generator 6s has an elliptical shape, and bearings 7 and A7 are interposed on the outer circumferential surface 66 of the web generators A and 5 along the outer circumferential surface 66. On the outside of this bearing t7, a rotatable ring 6g having a large number of serrated teeth formed on its outer periphery is rotatably disposed. On the other hand, the covered plate and the cylindrical shaft SO
In this case, cheeky lath splines 69 and 70 each having a large number of internal teeth meshing with the teeth of the flexible ring 68 are fixed to the pins 7/7.2. The number of internal teeth of the cheeky lath spline 69 is made equal to the number of teeth of the flexible ring 6g, and the cylindrical shaft S
The number of internal teeth of the cheeky lath spline 70 of O is slightly larger than the number of teeth of the flexible ring 6g.

Therefore, when the web generator fitted on the shaft sg rotates, the flexible ring A8 is elastically deformed. The meshing position between A8 and this cheeky lath spline 70 moves sequentially. When the web generator t5 rotates once, the cheeky lath spline 70 of the cylindrical shaft SO moves in the opposite direction to the rotational direction of the shaft sg by an amount greater than the number of teeth of the flexible ring 68.

For example, when the number of teeth of the cheeky lath spline 7Q of the cylindrical shaft 50 is greater than the number of teeth of the flexible ring 68, the reduction ratio l is calculated by setting the number of teeth of the flexible ring 6g to zf, and the number of teeth of the cheeky lath spline 70. If the number of teeth is ZC (that is, Zf+2), then generally i = i7'ro to i7. zt evening
A large reduction ratio can be obtained.

A cylindrical tip casing 7 is provided in front of the cylindrical shaft SO.
A support member 75 is rotatably supported inside the tip casing 73 via a bearing 7t, and a support member 7j is provided on the front surface of the support member 7j. A shaft 7q is freely rotatable through a bearing 7g inside the support member 7S to which the hand member B, which is used to grip or support a tool or workpiece (not shown), is fixed by a screw member 76 or a pin 77. A bevel gear O that meshes with the bevel gear 5 is fitted into the end of the shaft 7.

This bevel gear gO is supported by a bearing groove provided on the cylindrical shaft 50, and the axis of the shaft 7 is perpendicular to the axis of the cylindrical shaft 3o. A web generator 3 of a harmonic drive mechanism B is fitted onto the shaft 7. The structure of the web generator g3 is the same as that of the harmonic drive mechanism g3 mentioned above, so a detailed explanation will be omitted.
A flexible ring gS is disposed on the outer periphery of the bearing via the bearing plate ga, and the teeth of this flexible ring are fixed to the cylindrical shaft 50 and the support member 7S by pins gA and g7, respectively. The internal teeth of f7 are in mesh with each other. The number of internal teeth of the cheeky lath spline 5g of the cylindrical shaft 50 is equal to the number of teeth of the flexible ring 8, and the number of internal teeth of the cheeky lath spline g9 of the support member 7j is equal to the number of teeth of the flexible ring 8. The number is said to be slightly larger than the number of teeth on a ring zaza.

Therefore, the rotation of the shaft 7 is transmitted to the support member 75 with a large deceleration.

Next, the operation of the above-mentioned embodiment will be explained. In order to perform the twisting motion shown by α in FIG. 2, it is sufficient to drive the actuator≠a. Then, the outermost transmission shaft and 8 rotate via the reducer ja and the spur gear 7.7,
Wrist device/A is twisted in the α direction. 1, when actuator≠C is driven, transmission shaft 1c, bevel gear, 37, gear 0
, the shaft 3g is rotated via the spur gear U, and this shaft S
The rotation of the shaft is greatly reduced through the harmonic drive mechanism 611 and transmitted to the cylindrical shaft SO.
is swung in the β direction in Figure 1. Furthermore, when actuator +b is driven, the shaft 77 is rotated via the transmission shaft yb, bevel wheel 3.33, spur gear 3da, SS, and bevel gears s7 and s'o, and the rotation of this shaft 7 is harmonic. The speed is greatly reduced and transmitted to the support member 75 via the drive mechanism 4, and the hand member 2, which is integrated with the support member 7S, is rotated in the α direction in FIG.

In the above-mentioned embodiment, the harmonic drive mechanism 14L1 is provided in the final stage of the power transmission system that swings the cylindrical shaft 50 and rotates the hand member A. Bevel gear leading to 4 3.33
．． 37, G O, S F, Z O and spur gear 311. To Hiro 5
The paraclarity in the meshing of 5 and 6J is reduced by the reduction ratio, and becomes negligible in the operation of the cylindrical shaft 3o, which is the final output member, and the hand member B, and the positioning accuracy is improved. Moreover, the labor required during assembly to eliminate paraclarity is significantly reduced.

The wrist device/A is roughly composed of a U-shaped wrist casing 2J, a cylindrical shaft 50, and a tip casing 73 attached to the front of the cylindrical shaft 50. By making the joint surface of the tip casing 73 inside the outer diameter of the bearing μ9 as shown in FIG.
It is possible to insert the cylindrical shaft 50 into the wrist casing Δ with the tip casing 73 removed, and assembly and disassembly are extremely easy. Moreover, a bevel gear 33 and a spur gear 3t (
Xyo and Hiro/, s) and! ! ; Since the X or 62 is attached and further fixed to the wrist casing Δ and the cylindrical shaft 50 via the sleeve kota and phantom, maintenance such as checking the tooth surface is also easy when adjusting the tooth contact b. can be done.

Furthermore, bevel gears and spur gears used in the wrist device IA,
Since the shaft and bearings transmit power at high speed and low torque, they can be small, and the entire wrist device can be made smaller and lighter. Also, regarding movement interference,
Bevel gears 2g and 3 are created by the twisting action of the wrist device/A in the α direction.
The relative movement caused by the meshing of 3 and 37 with lθ is
Each is decelerated by a harmonic drive mechanism 6111 and 4 at a large reduction ratio, while the cylindrical shaft SO in the β direction
The relative motion caused by the meshing of the bevel gear S7 and the tooth θ due to the swinging action is the same.Since it is decelerated by the harmonic drive mechanism tooth, the influence on the operation of the output shaft is so small that it can be ignored. The problem is nameless.

In addition, in this embodiment, the λ pair of spur gears 3q and tAl and 62
However, a timing belt and pulley, or a chain and sprocket, etc. may be used in place of these.

〔Effect of the invention〕

As explained above, the wrist device for an industrial robot according to the present invention has three degrees of freedom and is driven by an actuator provided in an arm at the base. three transmission shafts arranged to protrude concentrically from the arm; a wrist casing protruding from the outermost transmission shaft; a cylindrical shaft that is supported so as to be able to rotate as an axial center of the transmission; a high reduction ratio reducer that reduces the rotation of the intermediate transmission shaft and transmits it to the cylindrical shaft;
a hand member supported in front of the cylindrical shaft so as to be rotatable about an axis perpendicular to the cylindrical shaft; and a hand member configured to reduce the rotation of the innermost power transmission shaft. Since it has a reduction gear with a high reduction ratio for transmission, it is small and lightweight, and it is possible to minimize the decrease in positioning accuracy caused by paraclarity of gears, and furthermore, it is possible to ignore interference between movements between degrees of freedom. It can produce excellent results.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a conventional wrist device, FIG. 2 is a front view showing an embodiment of an industrial robot to which the wrist device according to the present invention is applied, and FIG. 3 is an example of the wrist device shown in FIG. FIG. 3 is a left side view of FIG. 3, and FIG. 3 is a longitudinal cross-sectional view of the wrist device shown in FIGS. R...Industrial robot), /, /A...Wrist device, Co...Arm, ≠1. ≠b, 4'c...actuator, &-...hand member, J' M, r b, J'
c...Transmission shaft, //. /Yu, /7. /g, /9. ;10.2g, 33. 37
．． gθ, S7. ZaO...Bevel gear, J...Wrist casing, ivy, 52...Sleeve, 3U, 5! l...
・Hollow shaft, 31A, IA/, 5J, 62...Spur gear, 39°38.79...Shaft, 30...Cylindrical shaft, bll, gs...Harmonic drive l, 6!
;, gs...web generator, A9.70.
gg, g9...circular spline, 73...
Tip casing. Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] In a wrist device for an industrial robot that has three degrees of freedom and is driven by actuators provided in an arm at the base, each wrist device is driven by an independent actuator and is arranged so as to protrude concentrically from the arm. three transmission shafts; a wrist casing protruding from the outermost transmission shaft; and a wrist casing supported in front of the wrist casing so as to be rotatable about an axis perpendicular to the transmission shafts. a cylindrical shaft, a high reduction ratio reducer that reduces and transmits the rotation of the intermediate transmission shaft to the cylindrical shaft, and a reducer located in front of the cylindrical shaft and perpendicular to the cylindrical shaft. A hand member supported so as to be rotatable about an axial center, and another reduction gear with a high reduction ratio that transmits the rotation of the innermost transmission shaft to the hand member at a reduced speed. Features: Industrial robot wrist device.