JPS632315Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wrist mechanism that can be used in industrial robots, manipulators, etc., and particularly relates to a bendable wrist mechanism with improved positioning accuracy.

Among industrial robots and manipulators, those used for welding, sealing, etc. are often required to work in narrow spaces, and the wrist of the robot holding the tool can be flexibly moved to any position or posture. At the same time, the tip of the robot is bent to increase the robot's application rate (total welding line length, sealing length, painted line length, etc. that can be used by the robot). %) is required. The magnitude of such application rate largely depends on the structure of the wrist, and it is desirable that the wrist be a so-called flexible wrist that can bend freely in addition to having many degrees of freedom.

However, conventional flexible wrists such as Utility Model No. 156581 and Utility Model Application No. 156581
The wrist described in Publication No. 160790 has a lot of play and backlash due to its mechanism, and is not suitable for work that requires a high degree of precision such as welding work. Also, it is difficult to calculate the position of the wrist tip coordinates, etc. There was a problem.

Therefore, it is an object of the present invention to provide a wrist mechanism for industrial robots, manipulators, etc., which is bendable, has a high positioning accuracy of the wrist tip, and has a degree of freedom in turning the bendable wrist tip. The purpose is to

Next, a case in which the present invention is applied to a wrist mechanism of a welding robot will be described in detail with reference to the accompanying drawings. Here, FIG. 1 is a side view of the entire welding robot, and FIG. 2 is a plan sectional view of a wrist portion according to an embodiment of the present invention attached to the tip of the second arm of the robot.

In FIG. 1, a beam 102 that is perpendicular to the plane of the paper is horizontally attached to a pedestal 101, and a cart 103 is guided along the beam 102 using rails 104 attached to the top and side surfaces of this beam 102. Run. A carriage screw 121 that passes through the carriage 103 in the horizontal direction is engaged with a female screw on the carriage side, and rotation of the carriage screw 121 drives the carriage 103 along the beam 102 in a direction perpendicular to the plane of the paper. A first arm 109 that is swingable in the direction of arrow θ1 is attached to the tip of the base 105 attached to the side of the trolley 103. A second arm 110 that can swing in the direction
is installed. A motor 106 attached to the side surface of the base 105 regulates the swing angle of the first arm 109, and a second arm lever that drives the second arm 110 is mounted on the back side of the motor 106 (not shown). 2nd for rotating 107
An arm motor is attached, and the tip of the second arm lever 107 is connected via a link 108 to a fulcrum 122 provided at the rear end of the second arm 110. The second arm lever 107 and the second
parallel to arm 110 and first arm 109
Since a parallel link is formed in which the and link 108 are parallel, when the second arm lever 108 is rotated by a motor (not shown), the second arm 11
0 is swung by the same angle in the direction of the arrow θ2 around the tip of the first arm 109. A flexible wrist mechanism 4 according to the present invention is attached to the tip of the second arm 110, in which a first wrist element 1, a second wrist element 2, and a third wrist element 3 are sequentially connected.

The first wrist element 1 to which the second and third wrist elements 2 and 3 are attached is moved to the second arm 110 by a motor 112 attached to the end of the second arm 110.
is rotated in the direction of arrow θ3 around the axis 113 of
The tool attachment shaft 5 attached to the tip of the third wrist element 3 is rotated in the direction of arrow θ5 around the axis 115 of the third wrist element 3 by the motor 111a attached to the end of the second arm 110. Ru. Further, the second wrist element 2 is swingable in the direction of θ41 relative to the first wrist element 1, and the third wrist element 3 is swingable in the direction θ42 relative to the second wrist element 2. 2. The rocking movement of the third wrist elements 2 and 3 is controlled by a motor 111 attached to the end of the second arm 110.
This is caused by a motor 111b (not shown) provided on the back side of a. A welding torch 119 is connected to the tool attachment shaft 5 via a bracket 114.
is installed. Note that the moving direction of the first arm 109 is indicated by arrow θ1, the swinging direction of the second arm 110 is indicated by arrow θ2, and the second arm 1 of the third wrist element 3 is
The swinging (bending) angle with respect to 10, that is, the combined angle of θ41 and θ42 is expressed as θ4. Reference numeral 120 denotes a cable that is a combination of a conduit cable, a power cable, a gas cable, etc. connected to the welding torch 119.

Next, referring to FIG. 2, the first wrist element 1 is rotated in the direction of θ3, the second and third wrist elements 2 and 3 are swung in the direction of θ4, and the tool attachment shaft 5 is moved in the direction of θ5. The wrist mechanism for causing the rotation to occur will be explained.

In FIG. 2, 6 is the turning motor 112.
The shaft is rotatably supported by the second arm 110 by a bearing 7 attached to the tip of the second arm 110, and has a gear 8 at the tip.
The shaft 9 is a rotating shaft connected to a motor 111a that causes the tool attachment shaft 5 to rotate, and is rotatably supported by a bearing 10 provided at the tip of the second arm 110. It has a gear 11 in the section. The gear 8 has a hollow shaft 13 supported by a second arm 110 via a bearing 12.
It meshes with a gear 14 fixed to one end of the
The hollow shaft 13 is equipped with a Harmonic Drive reducer (manufactured by Harmonic Drive Systems, trademark) 15.
A drive disk 15a is fixedly attached to the fixed external gear 15b of the harmonic drive reducer 15.
is fixed to the second arm side, and its driven external gear 15c is fixed to a rotation transmission disk 17 rotatably supported by the hollow shaft 13 via a bearing 16. This rotation transmission disk 17 is connected to the second arm 11
The wrist element 1 is fixed to the first wrist element 1 which is rotatably supported by a bearing 18 at the same time.

The gear 11 attached to the shaft 9 is a hollow shaft inserted into the hollow shaft 13 coaxially with the hollow shaft 13 rotatably supported by bearings 19 and 20 attached to the second arm 110. 21 and a bevel gear 23 attached to the other end of the hollow shaft 21.
meshes perpendicularly with a bevel gear 26 fixed to the end of a hollow transmission shaft 25 rotatably attached to the first wrist element 1 via a bearing 24.

A bearing 2 attached to the second wrist element 2 is provided at the center of the second wrist element 2, which is swingably attached to the hollow shaft 25 via a bearing 27.
A rotatable intermediate gear 29 is mounted on both sides by 8, and this intermediate gear 29 is attached to a gear 30, which is a type of second rotation transmission member, fixed to the end of the transmission shaft 25. It's meshing with each other.

A hollow transmission shaft 32 rotatably supported on the second wrist element 2 via a bearing 31 so as to be parallel to the transmission shaft 25 has a gear at its end, which is a type of second rotation transmission member. 33 is fixed, and this gear 33 and the intermediate gear 29 mesh with each other. The transmission shafts 25 and 32 are both arranged perpendicular to the axis of each wrist element.

The third wrist element 3 is rotatably supported at one end by the transmission shaft 32 via a bearing 34.
It has a substantially cylindrical tip member 35 integrally at its end, and a bearing 3 attached to this tip member 35
A bevel gear 38 fixed to the end of the shaft 37 rotatably supported by the transmission shaft 32 meshes orthogonally with a bevel gear 39 fixed to the end of the transmission shaft 32.
A harmonic drive reducer 40 is built in the tip member 35, and the shaft 37 integrally has a driving disk 40a of the harmonic drive reducer, and is fixed to the tip member 35. One end of a flexspline 40d interposed between the fixed external gear 40b and the drive disc 40a is connected to the tool attachment shaft 5 supported by the tip member 35 via a bearing 41.

Further, a shaft 42 connected to a motor 111b (not shown) that allows each wrist element to bend freely has one end rotated by a bearing 43 attached to the inner diameter of a bevel gear 23 fixed to the hollow shaft 21. The bevel gear 44 is fixedly supported at the distal end thereof. This bevel gear 44 is connected to the transmission shaft 25
is perpendicular to a bevel gear 48 provided at the center of a connecting shaft 47 which has one end supported via a bearing 45 and the other end rotatably supported by a bearing 46 attached to the first wrist element 1. They mesh together. As shown in the figure, this connecting shaft 47 is coaxially inserted into the hollow part of the hollow transmission shaft 25, and therefore the first wrist element 1
is arranged perpendicular to the axis of the This connecting shaft 47 has a harmonic drive reducer 4 in the middle part.
9 is fixed to the drive disk 49a, and the fixed external gear 49b of this harmonic drive reducer 49 is fixed.
is fixed to the first wrist element 1, and the driven external gear 49c is fixed to the second wrist element 2. Furthermore, the second
The wrist element 2 is disposed on both sides of the first and third wrist elements 1 and 3, and is connected therebetween by a rib 50.

The connecting shaft 47 has a gear 51 fixed to its end (the end opposite to the transmission shaft 25), which is a type of first rotation transmission member, and this gear 51 is attached to the second wrist element 2 with a bearing. It meshes with an intermediate gear 53 which is rotatably supported on both sides by 51. Furthermore, this intermediate gear 53 is rotatably supported at one end by a bearing 54 on the second wrist element 2, and at the tip of a connecting shaft 56 whose other end is rotatably supported by a bearing 55 attached to the transmission shaft 32. It meshes with a gear 57 provided in the section.

The connecting shaft 56 integrally has a driving disk 58a of the harmonic drive reducer 58 fitted between the second wrist element and the third wrist element, and the fixed side of the harmonic drive reducer 58 The external gear 58b is fixed to the second wrist element 2, and the driven external gear 58c is fixed to the third wrist element 3.

Here, the harmonic drive reduction gear will be briefly explained with reference to FIG. As shown in the figure, the harmonic drive reducer has an elliptical drive disc B attached to the shaft A, and a ring-shaped drive disc B made of a material that can be easily bent through a plurality of rotating rollers R on the outer periphery of the drive disc B. The flexible spline C has a plurality of external teeth D on its outer periphery, and the external teeth D have a perfect circular shape in the fixed external gear E mounted on the outside thereof. The long diameter portion meshes with the internal teeth F formed in the inner teeth F, and the short diameter portion is separated from the inner teeth F. The number of teeth of external teeth D is the same as that of internal teeth F.
The pitch of both is the same. For example, if there are 200 external teeth D,
The number of internal teeth F is approximately 202. Further, a driven external gear G (not shown) adjacent to the fixed external gear E is meshed with the flexspline C, and the number of internal teeth of the driven external gear G is equal to the number of external teeth of the flexspline C. adjusted to be the same. That is, the internal teeth of the driven external gear and the external teeth of the flexspline C are formed such that the pitch of the external teeth of the flexspline C is slightly wider than the pitch of the internal teeth of the driven external gear G. Therefore, drive disk B is indicated by arrow H
When rotated as shown, the flexspline C
The external teeth D of the fixed side external gear E and the internal teeth F of the stationary external gear E are successively meshed with each other, and when the drive disk B rotates once, the flexspline C rotates in the opposite direction to a position delayed by two teeth. Since the flexspline C and the driven external gear G have the same number of teeth, the driven external gear G rotates in synchronization with the rotation of the flexspline. G now rotates in the opposite direction by two teeth, and its reduction ratio is 2/
200=1/100. In the above explanation, E is fixed and G is set to the driven side, so G will rotate in the opposite direction to the drive disk 37 at a deceleration speed of 1/100. The gear E rotates at a reduced speed in the same direction as the drive disk 37.

Therefore, for example, regarding the harmonic drive reducer 49 attached to the connecting shaft 47, when the reduction ratio is 1/100, when the connecting shaft 47 rotates 20 times, the driven external gear 49c and the second wrist element fixed thereto are 2 rotates at a speed of 0.2 rotations, that is, 72 degrees relative to the first wrist element 1. Further, the rotation of the connecting shaft 47 is transmitted to the other connecting shaft 56 via the gears 51, 53, 57, and the connecting shaft 56 rotates in the same direction as the connecting shaft 47.
Due to this rotation, the driven external gear 5 of the harmonic drive reducer 58 is combined with the connecting shaft 56.
8c, and the third wrist element 3 fixed thereto rotates the second wrist element 2 at a reduction ratio of 1/100 with respect to the rotation of the connecting shaft 56, as in the case of the harmonic drive reducer 49 described above. Rotate at low speed in the same direction as the direction. However, in the rotation movement after the second wrist element, the number of rotations of the connecting shaft 56 is affected by the rotation angle of the second wrist element 2, so the final swing angle of the third wrist element is determined by the rotation angle of the second wrist element 2. It is necessary to calculate by correcting the rotation angle of the element.

Next, for the wrist mechanism with the above structure, θ3
The operation for the degree of freedom of θ5 will be explained to help understand the present invention. First, when the motor 112 rotates and the shaft 6 rotates, this rotation is transmitted to the hollow shaft 13 via the gears 8 and 14, and the rotation of the hollow shaft 13 causes the driven external gear 15c of the harmonic drive reducer 15 to rotate. rotates at a reduced speed with respect to the rotational speed of the hollow shaft 13, and the first wrist element 1 fixed to this driven side external gear 15c via the rotation transmission disk 17 rotates at a low speed around the shaft 42. The entire wrist mechanism 4 consisting of the wrist element 1 and the wrist elements after the first wrist element 1 attached thereto rotates around the shaft 42 at a low speed.

Further, when the shaft 9 rotates due to the rotation of the motor 111a, this rotation is transmitted to the hollow shaft 2 through the gears 11 and 22.
1, the bevel gear 23 fixed to the hollow shaft 21, the bevel gear 26 meshing with the bevel gear 23, and the transmission shaft 25 integral with the bevel gear 26 rotate at high speed. The rotation of the transmission shaft 25 is further caused by gears 30, 29, 3.
3 to the other transmission shaft 32, and further rotates the shaft 37 via bevel gears 39 and 38. axis 37
When rotates, this rotation is transmitted to the harmonic drive reducer 40, and the tool attachment shaft 5 fixed to the flex spline 40d of the harmonic drive reducer 40 rotates at a low speed.

The above harmonic drive reducer 15 and 40
is attached to the end of various rotation transmission gear trains, and is configured so that the first wrist element 1 and tool attachment shaft 5, which are the final targets of rotation, are directly attached to the harmonic drive reducer. As mentioned above, these reducers reduce the rotational speed at a large reduction ratio, so there may be backlash or uneven rotation due to the backlash of the gears installed on the input side of the harmonic drive reducer, a chain (not shown), a timing belt, etc. is reduced by the reduction ratio of this reducer and transmitted to the final rotating object, so
As a result, uneven rotation of the first wrist element 1 and the tool attachment shaft 4 is eliminated, and extremely high positioning accuracy can be obtained. Such an effect is similarly exhibited by the harmonic drive reduction gears 49 and 58 for giving the wrist flexibility in bending, which will be described below.

Furthermore, when the shaft 42 rotates due to the rotation of the motor 111b (not shown), the rotation is caused by the bevel gears 44, 48.
The rotation is simultaneously transmitted to the adjacent connecting shaft 56 via the gears 11, 53, 57 as described above. At the same time, the rotation of the connecting shaft 47 rotates the drive disk 49a of the harmonic drive reducer 49, and this rotation is decelerated and transmitted to the driven external gear 49c.
The second wrist element 2 fixed to the second wrist element 9c is rotated at a low speed about the connecting shaft 47, and the rotation of the connecting shaft 56 is similarly slowed down via the harmonic drive reducer 58. This is transmitted to the wrist element 3, and the second and third wrist elements are bent in the same direction by the amount of θ41 and θ42, and the third wrist element and the tool attachment shaft 5 built therein are bent with respect to the second arm 110. and is bent by θ4. In this way, the rotation of the shaft 6 causes the entire wrist mechanism 4 to pivot around the axis of the second arm 110, and the rotation of the shaft 9 causes the tool attachment shaft 5 to rotate to the third wrist regardless of the movement of the wrist mechanism 4. It is understood that the second and third wrist elements are pivoted about the axis of the element, and that rotation of the shaft 42 causes the second and third wrist elements to swing and bend, respectively, in the same direction relative to the first wrist element; Since all of the driven objects in these drive systems are directly connected to the reducer and driven, the effects of uneven rotation and backlash before the reducer are ignored, improving the positioning accuracy of the driven objects.

The above explanation merely describes one representative example of the present invention; for example, each harmonic drive reducer used as a reducer can be replaced with a planetary gear reducer, a planetary roller reducer, or others. Further, the gears 30, 29, 33 and 51, 53, 57 used as the first and second rotation transmission means can be replaced with a chain, a timing belt, or other rotation transmission means, and the umbrella shown as the mesh transmission means It is also possible to replace the gears 44, 48, 39, 38, etc. with other spherical joints, worms, worm wheels, etc.

Furthermore, in FIG. 2, the tool mounting shaft 5 is connected to the connecting shaft 56.
Although a case has been shown in which they are arranged at right angles to each other, this is just an example, and they do not necessarily have to be arranged at right angles, but may just be connected in a cross-like manner. Also, in the above explanation, the suspension type welding robot was described, but this is just an example, and it is naturally applicable to other general articulated robots, manipulators, and orthogonal types. It can also be applied to sealing work, painting robots, manipulators, and various other machine tools. Furthermore, although the degree of freedom of bending the wrist has been explained only for the second wrist element and the third wrist element, the same applies to the case where the fourth and fifth wrist elements are further connected to the tip of the third wrist element. It is.

As described above, the present invention constitutes a set of wrist joints by one driving side wrist element and one driven side wrist element that swings with respect to the driving side wrist element. In wrist mechanisms such as industrial robots in which the joints are successively connected and can be bent freely, the driving side wrist element and the driven side wrist element are connected by a connecting shaft perpendicular to the axes of both wrist elements. A speed reducer is interposed between each connecting shaft and the driven wrist element to decelerate the rotation of the connecting shaft and transmit it to the driven wrist element. The wrist elements are connected by a first rotation transmission member to provide flexibility in bending between them, and each wrist element is provided with a transmission shaft coaxial with the connection shaft, and the adjacent transmission shafts are connected to each other by a first rotation transmission member. The tool mounting shaft is connected by two rotation transmission members, and furthermore, the transmission shaft at the most distal end portion and the tool mounting shaft are connected in a cross-shaped manner via an interlocking transmission mechanism to give the tool mounting shaft a degree of freedom in turning. Since this is a wrist mechanism for an industrial robot, etc., the mechanism that drives the wrist part is all controlled by simple rotational movement, so the calculations to determine the position coordinates of the tip of the wrist are much easier than with conventional flexible wrist mechanisms. Furthermore, the bending angle of one joint can be increased compared to the conventional link type flexible wrist, and the application rate of the robot can be improved. Furthermore, since the final driven element is directly driven by the output side of the reducer, the positioning accuracy of the driven object is not affected by backlash or uneven rotation before the reducer, resulting in extremely high positioning accuracy. In addition, since the tip of the wrist can freely rotate independently of the rotation of the entire wrist and the swinging movement of the wrist, it is not necessary to rotate the painting gun itself, as in the case of, for example, painting robots. It is extremely suitable for application to robots and manipulators.

[Brief explanation of the drawing]

Fig. 1 is a side view of the entire welding robot having a wrist element which is an embodiment of the present invention, Fig. 2 is a cross-sectional plan view of the wrist element, and Fig. 3 is a harmonic that can be used in the embodiment. FIG. 2 is a front sectional view showing the principle of a drive reducer. Explanation of symbols, 1, 2, 3...Wrist element, 4...
Wrist mechanism, 5... Tool attachment axis, 6, 9, 42
...Shaft, 47, 56...Connection shaft, 25, 32...
Transmission shaft, 15, 40, 49, 58... Harmonic drive reducer, 51, 53, 57... Gear (first rotation transmission member), 29, 30, 33... Gear (second rotation transmission member) ), 38, 39...Bevel gear (meshing transmission mechanism).

Claims (1)

[Claims for Utility Model Registration] 1. A pair of wrist joints is composed of one driving wrist element and one driven wrist element that swings with respect to the driving wrist element, and two or more In a wrist mechanism such as an industrial robot in which the wrist joints are sequentially connected and can be bent freely, the driving side wrist element and the driven side wrist element are connected by a connecting axis perpendicular to the axes of both wrist elements. A reducer is interposed between each connecting shaft and the driven wrist element to decelerate the rotation of the connecting shaft and transmit it to the driven wrist element. The first
A rotation transmission member connects the wrist elements to provide a degree of freedom in bending between the wrist elements, and a transmission shaft coaxial with the connection shaft is attached to each wrist element, and the adjacent transmission shaft is connected to a second rotation transmission member. An industrial robot, etc., which is connected by a member, and furthermore, a transmission shaft at the leading end and a tool mounting shaft are connected in a cross-shaped manner through an interlocking transmission mechanism to give the tool mounting shaft a degree of freedom in rotation. wrist mechanism. 2. The wrist mechanism as set forth in claim 1 of the utility model registration claim, in which the meshing transmission mechanism and the tool attachment shaft are connected via a speed reducer.