JPH06226679A - Joint drive mechanism for robot arm - Google Patents

Abstract

PURPOSE:To enlarge the rotating angle of an arm so as to enlarge the action range of a robot by providing idle pulleys in proximity to a drive side and a driven side pulleys, and winding a steel belt in the crossed state around the idle pulleys as well as crossing the steel belt. CONSTITUTION:A drive side pulley 3 is fixed to a driving shaft 2 provided at one end of a first arm 1 and driven by a driver, and a driven side pulley 5 is fixed to one end of a driven shaft 4 supported through a bearing at the other end of the first arm 1. A second arm 6 is then fixed to the other end of the driven shaft 4. Two idle pulleys 7, 8 are disposed in proximity to the respective pulleys 3, 5. The idle pulley 7 is rotatably supported at the supporting part 71, fixed to the first arm 1, through a spring 72, and the idle pulley 8 is journalled to a supporting shaft 81 fixed to the first arm 1. A steel belt 9 with a wide width part 91 and a narrow width part 92 crossed and formed into approximately 8-shape at both ends is stretched over both pulleys 7, 8 to perform power transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for driving a joint of a robot arm.

[0002]

2. Description of the Related Art Conventionally, as a joint drive mechanism between two arms, as shown in FIG. 8, a drive shaft 2 and a driven shaft 4 which are parallel to each other are provided in one of the first arms 1 and Driven shaft 4
The two steel belts 9 and 9 ′ are hung on the driving side pulley 3 and the driven side pulley 5, which are respectively fixed to
Disclosed is that the ends of steel belts 9 and 9'are respectively fixed to a driving pulley 3 and a driven pulley 5, the driving shaft 2 is coupled to a driving device, and the driven shaft 4 is fixed to a second arm 6. (For example, Japanese Patent Laid-Open No. 3-234495)
issue).

[0003]

However, in the above configuration, when the distance between the two rotating shafts, the drive shaft 2 and the driven shaft 4, is long, the diagonal angle θ at the intersection of the steel belts 9 and 9'is crossed. Since it becomes smaller, the winding angle α around which the steel belt is wound around the drive side pulley 3 or the driven side pulley 5 becomes smaller than that in the case where the distance between the drive shaft 2 and the driven shaft 4 is short, and the operating range of the robot is reduced. It had the drawback of becoming narrower. Further, there is a problem in that the slack and vibration of the steel belt due to secular change, temperature change and tension change cannot be prevented by simply stroking the steel belt over the two pulleys. SUMMARY OF THE INVENTION It is an object of the present invention to provide a joint drive mechanism for a robot arm which has a wide wrapping angle of a steel belt and has a wide range of arm movements and performs stable movements even if the distance between two rotary shafts is long. It is what

[0004]

According to the present invention, a drive shaft is rotatably supported at one end and a driven shaft is rotatably supported at the other end, and a first arm fixed to the driven shaft. 2 arms, a drive side pulley fixed to the drive shaft, a driven side pulley fixed to the driven shaft, a drive side pulley and the driven side pulley, and both ends of the driven side pulley and the driven side pulley, respectively. In a joint drive mechanism of a robot arm including a steel belt fixed to the driven pulley, an idle pulley is provided near one or both of the drive pulley and the driven pulley, and the drive pulley and the idle pulley are provided. And the steel belt is crossed between the driven pulley and the idle pulley.

[0005]

[Operation] Since the steel belt is wound around the driving pulley and the idle pulley and between the driven pulley and the idle pulley, the steel belt is wound around the driving pulley and the driven pulley in comparison with the steel belt. The diagonal angle θ at the intersection of the crossing is increased, and the winding angle α of the drive pulley and the driven pulley is increased. Therefore, the rotation angle of the second arm is increased and the operation range of the robot is expanded. In addition, since the idle pulley is pressed by a spring so as to approach the driving side pulley or the driven side pulley, when an excessive load is applied to the second arm, the bending of the spring absorbs the tension of the steel belt, It is possible to prevent the steel belt from being cut and the robot arm from being impacted. Furthermore, since the tension is applied to the steel belt by a spring, it is possible to prevent the steel belt from sagging due to secular change, temperature change, and tension change, and by supporting the idle pulley via a damping device, the vibration of the steel belt can be prevented. Can be prevented.

[0006]

Embodiments of the present invention will be described with reference to the drawings.
1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a side sectional view thereof. A drive shaft 2 driven by a drive device 21 is provided at one end of a first arm 1, and the drive shaft 2 has a drive side. Pulley 3
Is fixed. A driven shaft 4 is supported at the other end of the first arm 1 via a bearing 41, a driven pulley 5 is fixed at one end of the driven shaft 4, and a second arm 6 is fixed at the other end. There is. Two idle pulleys 7 and 8 are provided between the driving pulley 3 and the driven pulley 5, respectively.
The idle pulley 7, which is disposed close to the driven pulley 5 and is located near the drive pulley 3, is rotatably supported by a support portion 71 fixed to the first arm 1 via a spring 72. The idle pulley 8 located near the driven pulley 5
Are rotatably supported by a support shaft 81 fixed to the first arm 1. A steel belt 9 is wound around the drive side pulley 3 and the driven pulley 5, and the steel belt 9 has a length of 1 in the longitudinal direction of the steel belt 9 as shown in FIGS. 3 (a) and 3 (b). A wide portion 91 in which the width of the / 2 portion is made wider than the other half of the remaining 1/2 portion and a narrow portion 92 are formed in the remaining portion. Elongated holes 93 are provided at both ends of the wide portion 91 along the longitudinal direction of the steel belt 9, and the narrow portion 92 passes through the elongated hole 93. One end of the wide portion 91 is fixed to one point on the outer periphery of the drive pulley 3 with a fixing screw 94, and the wide portion 9 is wound around the outer periphery of the drive pulley 3,
The idle pulley 7 is wound around the idle pulley 7 and the drive pulley 3, and then the idle pulley 8 is wound around and the idle pulley 8 and the driven pulley 5 are passed through the idle pulley 7.
The other end of the wide portion 91 is fixed to one point of the driven pulley 5 with a fixing screw 95. The narrow portion 92 passes through between the idle pulley 7 and the drive side pulley 3 and the idle pulley 7
The idler pulley 8 and then the idler pulley 8 and the driven pulley 5 through the idle pulley 8 and the outer circumference of the driven pulley 5. The other end is fixed by a fixing screw 94.
The wide portion 91 and the narrow portion 92 of the steel belt 9 cross the drive side pulley 3 and the idle pulley 7 and between the driven side pulley 5 and the idle pulley 8 in a crossing manner. Is always pressed by the spring 72 so as to approach the drive pulley 3. Further, as shown in FIG. 3 (a), the steel belt 9
Insert the intersecting portion of the narrow portion 92 of the above into the oblong hole 93 of the wide portion 91, and fix both ends to the outer periphery of the driving side pulley 3 and the driven side pulley 5 with fixing screws 94 and 95, respectively.
The intersecting parts do not interfere with each other.

Thus, the wide portion 9 of the steel belt 9 is
Since 1 and the narrow portion 92 pass between the drive side pulley 3 and the idle pulley 7 and between the driven side pulley 5 and the idle pulley 8, the diagonal angle θ at the intersection of the crossing of the steel belt 9 increases, The winding angle α of the drive pulley 3 and the driven pulley becomes large. Therefore the second
The rotation angle of the arm increases, and the operating range of the robot increases. Further, since the idle pulley 7 is pressed against the drive pulley 3 side by the spring 72, the slack and vibration of the steel belt 9 can be prevented. Further, since the narrow portion 92 of the steel belt passes through the elongated hole 93 provided in the central portion of the wide portion 91, a moment for tilting the shaft supporting the pulley such as the drive shaft and the support shaft does not work, It is possible to perform stable winding transmission operation. As shown in FIG. 3 (c), the steel belt 9 is divided into two parts, a wide part 91 and a narrow part 92, each end of which is fixed to the driving pulley 3 and the driven pulley 5 with a screw 9
It may be fixed by 4, 95. In addition, the elongated hole 93 provided in the wide portion 91 has the same shape as that shown in FIGS.
As shown in (c), one communicating long hole may be formed. FIG. 5 is a plan view showing a second embodiment, in which the idle pulleys 7 and 8 are supported on the first arm 1 by a support shaft, the middle of the steel belt 9 is coupled by a spring 72, and tension is directly applied to the steel belt. In addition, it is designed to prevent vibration and slack. FIG. 6 is a plan view showing a third embodiment, in which both the idle pulleys 7 and 8 are supported by the first arm 1 so that they can be moved to the left and right, and a spring 72 is provided between the idle pulleys 7 and 8. And a damping device 73 such as a dashpot are inserted, and the idle pulleys 7 and 8 are pressed against the drive pulley 3 and the driven pulley 5, respectively,
The steel belt 9 is prevented from sagging and the idle pulleys 7 and 8 and the steel belt 9 are prevented from vibrating. FIG. 7 shows a fourth embodiment in which the idle pulley 8 is provided only near the driven pulley 5, and the steel belt 9 is wound between the driven pulley 5 and the idle pulley 8 to wind the driven pulley 5 around the idle pulley 8. The angle α is increased and the diameter of the drive pulley 3 is increased so that the drive pulley 3 can be rotated by the winding angle of the driven pulley 5. As a result, the structure can be simplified by providing one crossing and one idle pulley.

[0008]

As described above, according to the present invention, the idle pulley is provided near the driving pulley and the driven pulley, the steel belt is wound around the idle pulley, and the driving pulley and the driven pulley are wound. Since the hanging angle is large, the rotation angle of the arm is large and the operating range of the robot can be widened, and tension is applied to the steel belt by supporting the idle pulley via the spring and damping device. Therefore, there is an effect that slack and vibration of the steel belt can be suppressed, and cutting of the steel belt and impact on the robot arm and the like can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is a perspective view showing an embodiment of the steel belt of the present invention.

FIG. 4 is a perspective view showing another embodiment of the steel belt of the present invention.

FIG. 5 is a plan view showing a second embodiment of the present invention.

FIG. 6 is a plan view showing a third embodiment of the present invention.

FIG. 7 is a plan view showing a fourth embodiment of the present invention.

FIG. 8 is a plan view showing a conventional example.

[Explanation of symbols]

1 1st arm 2 Drive shaft 3 Drive side pulley 4 Driven shaft 5 Driven side pulley 6 2nd arm 7, 8 Idle pulley 71 Support part 72 Spring 73 Damping device 81 Support shaft 9 Steel belt 91 Wide part 92 Narrow part 93 length Holes 94, 95
Fixing screw

Claims (5)

[Claims] 1. A first arm having a drive shaft rotatably supported at one end and a driven shaft rotatably supported at the other end, a second arm fixed to the driven shaft, and the drive shaft. A fixed drive side pulley, a driven side pulley fixed to the driven shaft, and a steel fixed to the drive side pulley and the driven side pulley by winding them around the drive side pulley and the driven side pulley. In a joint drive mechanism of a robot arm including a belt, an idle pulley is provided in the vicinity of one or both of the drive side pulley and the driven side pulley, and between the drive side pulley and the idle pulley and the driven pulley. A joint drive mechanism of a robot arm, characterized in that the steel belt is crossed with the idle pulley. 2. A wide portion is formed by making a half width in a length direction from one end of the steel belt wider than a width of a narrow portion formed in the remaining half portion of the steel belt. The joint drive mechanism for the robot arm according to claim 1, wherein an elongated hole having a width wider than that of the narrow portion is provided in the portion, and the narrow portion is inserted into the elongated hole. 3. The joint drive mechanism for a robot arm according to claim 2, wherein the steel belt is divided into a steel belt having the wide portion and a steel belt having the narrow portion. 4. The joint drive mechanism for a robot arm according to claim 1, wherein the idle pulley is supported by the first arm via one or both of a spring and a damping device. 5. The joint drive mechanism for the robot arm according to claim 1, wherein the middle of the steel belt is connected by a spring.