JPH0811079A - Industrial robot drive - Google Patents

Abstract

(57) [Summary] [Purpose] The position of the robot and the generated torque are detected by removing the backlash of the reducer, the positioning accuracy of the robot is extremely good, and the change in the load applied to the arm from the outside such as deburring work is detected. Provide a drive unit for an industrial robot that can easily correct speed, etc. [Structure] 2 on the fixed base 7 of the drive unit of the industrial robot
Fixing the fixed parts 1a and 2a of the individual speed reducers 1 and 2 in succession,
The fixed shafts 1a and 2a are rotatably supported by the input shafts 3 and 4, the speed reduction parts 1c and 2c, and the low speed rotation output parts 1b and 2b.
Drivingly connected to a frame of a robot arm rotatably supported by, and rotatably and pivoting an input shaft 3 of one speed reducer 1 with respect to an input shaft 3 of the other speed reducer 2. Two input shafts 3 and 4 at the position where arbitrary initial torque is added
Fixed by connecting the two so that they do not rotate relative to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a drive unit of an industrial robot, and more particularly to an industrial robot in which a fixed base of the drive unit of the industrial robot rotatably supports a frame of a robot arm via a speed reducer. The present invention relates to the structure of a drive unit of a robot.

[0002]

2. Description of the Related Art An industrial robot having a structure in which a frame of a robot arm is rotatably supported by a fixed base of a drive unit of such a conventional industrial robot via a speed reducer is shown in FIG. Drive base fixed base 16
Fix the fixed part 21a of the speed reducer 21 to the
An input shaft 22, which is a high-speed input shaft, a reduction unit 21c, and a low-speed rotation output unit 21b of the reduction gear 21, are rotatably supported by a fixed unit 21a by a device (not shown), and the input of the input shaft 22 is the reduction unit 2.
The robot arm is decelerated by 1c and is output to the low speed rotation output part 21b which meshes with the speed reduction part 21c and is rotatable around the speed reduction part 21c. The low speed rotation output part 21b is rotatably supported by the fixed base 16. The power of the motor 20 connected to the frame 18 and fixed to the frame 18 is generated by the coupling 19
Is transmitted to the input shaft 22 via the speed reducer 21c and the low-speed rotation output part 21b, and is output to the frame 18 to be transmitted to the frame 18
It was a structure to rotate the robot arm connected with. The reduction gear 21 is, for example, a reduction gear such as RV-135 manufactured by Teijin Seiki Co., Ltd. In the reduction gear part, the gear fixed to the high-speed input shaft 22 meshes with three spur gears to decelerate, and the reduced three gears. Three planetary crankshafts, each fixed to a spur gear, two RV gears that are 180 degrees out of phase and further reduced by three planetary crankshafts, and two RV gears.
The low speed rotation output portion 21b meshes with the V gear, but it is well known and will not be described in detail.

[0003]

In the conventional structure, the load torque of the drive portion--the deflection angle curve is the load torque of the speed reducer--.
It is equal to the deflection angle curve, and generally there is backlash at zero load torque as shown in Fig. 4, and the rigidity of the reduction gear (load torque / deflection angle) is low in the region where the load torque is small (near torque) (deflection). It becomes easy) and becomes higher as the load torque increases (hard to bend). The change in rigidity decreased as the load torque increased, and the load torque-deflection angle curve became close to a straight line.
In a robot that uses a speed reducer with such backlash and further has a position detector in the motor section or in the path from the motor section to the speed reducer, the backlash of this speed reducer has a rotational position detector attached to the output shaft of the motor. It was undetectable because it was taken, and therefore it was out of control. For this reason, the backlash of the speed reducer is the main cause of the deterioration of the positioning accuracy of the robot, and especially the accuracy of the robot with a long arm was remarkable, but it was difficult to remove the effective backlash of the speed reducer. .

The rigidity of the speed reducer differs between the low torque region and the high torque region, and particularly in the low torque region, this rigidity is low (easy to bend) and the degree of change is rapid, so that deburring work and the like from the outside In the case of control in which changes in the load applied to the arm are detected and the position, generated torque, speed, etc. of the robot are corrected, it is not possible to correct the control target by approximating a straight line to the changes in the load torque. In other words, it was difficult to adopt a simple linear control, and it was difficult to make an appropriate correction. An object of the present invention is to provide a drive unit for an industrial robot, which solves the above-mentioned problems of the prior art and eliminates the backlash of the speed reducer and has extremely good robot positioning accuracy. Another object of the present invention is to provide a drive unit for an industrial robot that can detect a change in load applied to an arm from the outside such as deburring work and can easily correct the position, generated torque, speed, etc. of the robot. .

[0005]

SUMMARY OF THE INVENTION The present invention For this purpose, the respective fixing portions of the two reduction gear is axially fixed to the stationary base of the drive portion of the industrial robot, each of said reduction gear to each of said fixed portion The input shaft, the deceleration unit, and the low-speed rotation output unit are rotatably supported, and the input of each of the input shafts is decelerated by each deceleration unit and output to the low-speed rotation output unit. Drivenly connected to a frame of a robot arm rotatably supported on the fixed base, and rotatably and rotatably with respect to the input shaft of one speed reducer and the input shaft of the other speed reducer. At the position where an arbitrary initial torque is added, the above 2
The above-mentioned problems of the prior art have been solved by providing a drive unit for an industrial robot, characterized in that the two input shafts are connected so as to be fixed so as not to rotate relative to each other. In the present specification, the fixed portion of the reduction gear means the entire structure that rotatably supports the input shaft, the reduction portion, and the low-speed rotation output portion of the reduction gear.

[0006]

According to the present invention, + T is applied to the speed reducer 1 as shown in FIG.
An initial torque of −T can be applied to the speed reducer 2, and by combining two curves, a load torque-deflection angle curve of the drive unit as shown in FIG. 6 can be obtained, eliminating backlash of the drive unit and increasing rigidity. Can be increased and the change in rigidity can be reduced (the load torque-deflection angle curve is close to a straight line).
In addition, since the load on the output side is supported by the two speed reducers, a small speed reducer can be used and the size can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the attached FIG. FIG. 1 is a partially cutaway schematic cross-sectional view showing the structure of a drive unit of an industrial robot according to an embodiment of the present invention. Two parts are attached to a fixed base 7 of the drive unit of the industrial robot via a mounting base 5. The fixed shafts 1a and 2a of the speed reducers 1 and 2 are continuously fixed in the axial direction, and an input shaft that is a high-speed input shaft of the speed reducers 1 and 2 is provided by a device shown in part on each of the fixed parts 1a and 2a. 3, 4,
The speed reducing parts 1c, 2c and the low speed rotation output parts 1b, 2b are rotatably supported, and the inputs of the input shafts 3, 4 are decelerated by the speed reducing parts 1c, 2c to mesh with the speed reducing parts 1c, 2c. Is output to the low speed rotation output sections 1b and 2b that are rotatably made to rotate, and each low speed rotation output section 1b and 2b is connected to a frame of a robot arm rotatably supported by a fixed base 7, and The two input shafts 4, 3 are connected at a position where the input shaft 3 of the other speed reducer 1 is rotatable with respect to the input shaft 4 of the one speed reducer 2 and a desired initial torque is applied. By doing so, the two are fixed so as not to rotate relative to each other.

In the embodiment shown in FIG. 1, the fixed portion 1a of the reduction gear 1 is attached to the mounting base 5 attached to the fixed base 7, and the reduction gear is attached to the common base 6 fixed to the fixed portion 1a of the reduction gear 1. Two fixed portions 2a are continuously fixed to the reduction gear 1 in the axial direction. The hollow input shaft 4 is connected to an output shaft 12a of a motor 12 mounted on a motor base 8 fixed to a frame 9 via a coupling 11 and is rotatably supported by the motor base 8. The input shaft 3 is rotatably supported by a hollow input shaft 4 and a mounting base 5. Here, the pressing plate 10 fixed to the input shaft 3 of the speed reducer 1 presses the spanning ring 13, which is a friction fastening member, so that the input shaft 3 and the input shaft 4 are fixed so as not to rotate relative to each other, and are fixed to the frame 9. When there is an output from the output shaft 12a of the fixed motor 12, it is transmitted in synchronization with the input shafts 3 and 4 via the coupling 11, and is decelerated by the speed reduction units 1c and 2c to output the low speed rotation outputs 1b and 2b. It is output to the frame 9 via the frame and rotates the frame of the robot arm with respect to the fixed base 7. The structure of the speed reducers 1 and 2 is the same as that of the speed reducer 21 of FIG. 7, and the details thereof will not be described.

Reference numerals 1d and 2d denote bolts. The bolt 1d fixes the common base 6 between the fixed portion 1a and the mounting base 5, and the bolt 2d fixes between the common base 6 and the fixed portion 2a. The deceleration parts 1c and 2c are rotatably supported by the fixed parts 2a and 1a by a known device (not shown), and the inputs of the input shafts 3 and 4 are input to the deceleration parts 1 and 2.
It is decelerated by c and 2c and is transmitted to the low speed rotation output sections 1b and 2b. With such a configuration, it is possible to apply an arbitrary initial torque to the speed reducer 1 and the speed reducer 2 by appropriately selecting the tightening margin of the pressing plate 10 fixed to the input shaft 3 of the speed reducer 1 or the span ring 13. . Alternatively, the fixed part 1a,
2a may be independently mounted on the fixed base 7 as a plane object, and the input shafts 3 and 4 may be mounted separately in parallel. FIG. 2 is a diagram showing a state in which an initial torque is applied. The input shaft 4 is fixed by a coupling 11 having a fixing jig 15 so as not to rotate, and the input shaft 3 is rotated with a constant torque by a torque wrench 14. By moving and pressing the pressing plate 10 fixed to the input shaft 3 at the position, the spanning ring 13 which is a frictional fastening member is pressed by the frictional fastening force of the spanning ring 13.
With the input shaft 4 fixed, the torque set by the torque wrench 14 can be applied to the speed reducer 1 and the speed reducer 2 as initial torque.

FIG. 3 is different from the embodiment of FIG. 1 in that the common base 6 of FIG. 1 is eliminated, and the speed reducer fixing portions 1a and 2a are integrated into one unit. 2c is supported by one speed reducer fixing part 24a, meshes with two speed reducing parts 1c and 2c, and is rotatable around the speed reducer low speed rotation output parts 1b and 2b shown in FIG. Low speed rotation output part 24b
Is an example. The fixed portion 24a of the speed reducer 24 is fixed to the fixed base 7 via the mounting base 5, and is connected to the output shaft 12a of the motor 12 fixed to the frame 9 and rotatably supported by the motor base 8. One end of the input shaft 3 of the other speed reducer 24e is rotatably supported in the hollow input shaft 4 of the speed reducer 24d, and the other end is rotatably supported by the mounting base 5, and the input shaft of one speed reducer 24d is further supported. 4, the input shaft 3 of the other deceleration part 24e is rotatable, and the two input shafts 3 and 4 are connected at a position where an arbitrary initial torque is applied by rotating them so that they do not rotate relative to each other. Thus, the low speed rotation output part 24b of the speed reducer 24 is connected to the frame 9. Here, the high-speed input shaft 4 and the high-speed input shaft 3 are fastened by pressing the spanning ring 13, which is a friction fastening member, with the pressing plate 10 fixed to the input shaft 3, and the power of the motor 12 is passed through the coupling 11. Is transmitted to the high speed input shafts 4 and 3 and is decelerated by the speed reduction units 24d and 24e to be output to the low speed rotation output unit 24b.
It is the same as in FIG. 1 in that the structure is such that it is output to the frame 9 via and is rotated. In the embodiment shown in FIG. 3, the fixed parts of the two speed reducers and the low-speed rotation output parts are integrated into one speed reducer to simplify the structure and reduce the number of parts to reduce the axial distance. Can be shorter and more compact.

[0011]

According to the present invention, the fixed parts of the two speed reducers are continuously fixed in the axial direction, and the input shaft, the speed reducer and the low speed rotation output part of each speed reducer can be freely rotated on the fixed part. To support
The input shaft of the other speed reducer can be rotated with respect to the input shaft of the other speed reducer, and the two input shafts are connected at a position where an arbitrary initial torque is added to the two input shafts so that they can be moved relative to each other. Since it is fixed so as not to rotate, it is possible to easily eliminate the backlash of the drive unit and to provide the drive unit of the industrial robot with extremely good positioning accuracy.
In addition, since the rigidity of the robot drive unit including the arm can be increased and the change in rigidity can be reduced, changes in the load applied to the arm from the outside such as deburring work can be detected, and the position, generated torque, and speed of the robot can be detected. It has become possible to provide a drive unit for an industrial robot that can easily correct such problems. Further, since the load on the output side is supported by the two speed reducers, a small speed reducer can be used and the robot arm can be made compact. In a preferred embodiment, the fixed parts of the two speed reducers and the low speed rotation output parts are integrated into one speed reducer to simplify the structure, reduce the number of parts, and shorten the axial distance. It provides a more compact industrial robot drive unit.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic sectional view showing a configuration of a drive unit of an industrial robot according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a device that applies an initial load torque to a drive unit of the embodiment industrial robot of FIG.

FIG. 3 is a partially cutaway schematic sectional view showing the configuration of a drive unit of an industrial robot according to an embodiment of the present invention, which is different from FIG.

4 is a load torque-deflection angle curve of a drive unit of the conventional industrial robot of FIG.

5 is a load torque-deflection angle curve in which an initial torque is applied to two speed reducers of the drive unit of the industrial robot of the embodiment of FIG.

FIG. 6 is a load torque-deflection angle curve synthesized by two speed reducers of the driving unit of the industrial robot of the embodiment shown in FIG.

FIG. 7 is a partially cutaway schematic cross-sectional view showing the configuration of a drive unit of a conventional industrial robot.

[Explanation of symbols]

 1, 2, 24 Reducer 1a, 2b, 24a Fixed part 1a, 2b, 24b Low speed rotation output part 1c, 2c, 24d, 24e Reducer part 1d, 2d Bolt 5 Mounting base 6 Common base 7 Fixed base 8 Motor base 9 Robot Arm frame 10 Holding plate 11 Coupling 12 Motor 12a Output shaft 13 Supane ring

Claims (3)

[Claims] 1. A fixed base of a drive unit of an industrial robot, each fixing unit of two speed reducers is continuously fixed, and each fixed unit has an input shaft, a speed reducing unit, and a low-speed rotation output of each speed reducer. The input shafts are decelerated by the deceleration units and output to the low-speed rotation output unit, and the low-speed rotation output units are rotatably supported by the fixed base. The input shaft of one speed reducer is rotatably connected to the frame of the robot arm, and the input shaft of the other speed reducer is rotatably and rotated at a position where an arbitrary initial torque is applied. A drive unit for an industrial robot, characterized in that by connecting two input shafts, they are fixed so as not to rotate relative to each other. 2. A fixed portion of one of the speed reducers is fixed to the fixed base, and a fixed portion of the other speed reducer is fixed to the common base fixed to the fixed portion continuously in the axial direction, and One end of the input shaft of the other speed reducer is provided in the input shaft of the hollow one speed reducer that is connected to the output shaft of the motor fixed to the frame and is rotatably supported by the motor base. The other end is rotatably supported by the mounting base, and the input shaft of the other speed reducer is rotated with respect to the input shaft of the one speed reducer to apply an arbitrary initial torque to both inputs. The input shaft of the other reduction gear is fixed by a pressing plate fixed to the input shaft of the other reduction gear so that both input shafts are fixed so as not to rotate relative to each other. Item 1 of the industrial robot Drive part. 3. A fixed base of a drive unit of an industrial robot is fixed to a fixed unit of a speed reducer having two reduction units and one low-speed rotation output unit, and the fixed units are provided with the respective reduction units, respectively. The input shafts of the speed reducers and the low-speed rotation output parts drivingly connected to the speed-reduction parts are rotatably supported, and the input of each input shaft is decelerated by the speed-reduction parts to the low-speed rotation output part. The low-speed rotation output unit is connected to a frame of a robot arm rotatably supported by the fixed base, is connected to an output shaft of a motor supported by a motor base fixed to the frame, and One end of the input shaft of the other speed reducer is rotatably supported in the input shaft of the one speed reducer rotatably supported by the motor base, and the other end is rotatably supported by the mounting base. Let
Further, the input shaft of the other speed reducing unit is rotatably connected to the input shaft of the other speed reducing unit, and the two input shafts are connected at a position where an arbitrary initial torque is applied to the input shaft of the other speed reducing unit. A drive unit for an industrial robot, which is fixed so as not to rotate relatively.