JP2005014100A - Wrist mechanism of industrial robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wrist mechanism of an industrial robot having a simple structure, reducing the number of components, and easy in installing a wiring cable. <P>SOLUTION: This wrist mechanism 1 of the industrial robot has a turning arm 2 freely turnable to a robot arm 11, a rocking arm 3 freely rockable to the rotary arm, and a freely turnable flange 4 mounted on the rocking arm. The rotary arm, the rocking arm, and the flange are driven by speed reducer integrated motors 21, 31 and 41 integrally incorporated with a speed reduction mechanism. The rotary arm, rocking arm, and flange are respectively directly connected to the corresponding motors. The wiring cable 7 is inserted into the respective motors, by arranging through-holes 24, 34 and 44 passing through the rotational axis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wrist mechanism that is rotatably attached to the tip of an arm of an industrial robot, and more particularly to a wiring cable installation structure in the wrist mechanism.
[0002]
[Prior art]
As this type of wrist mechanism, a structure shown in FIG. 2 is known (see, for example, Patent Document 1).
The wrist mechanism 101 is rotatably attached to the tip of the robot arm 111. The wrist mechanism 101 includes a rotation arm 102 provided to rotate with respect to the robot arm 111, a swing arm 103 that is swingably attached to the swing arm 102, and a rotatable arm mounted on the swing arm 103. The flange 104 is composed of three parts. The rotating arm 102 has a housing portion 102a, 102b with its tip portion bifurcated.
[Patent Document 1] Japanese Patent Application Laid-Open No. 60-197387
The rotating arm 102 is driven via a speed reducer 122, a driving gear 123, and a driven gear 124 by a motor 121 installed in the robot arm 111 while being shifted from the rotation axis of the rotating arm. The swing arm 103 is driven by a motor 125 attached on the rotating arm 102. The swing arm 103 and the motor 125 are connected to each other through a belt transmission mechanism 127 and a speed reducer 126 disposed on the housing portion 102a side. The flange 104 is driven via a speed reducer 129 by a motor 128 mounted on the swing arm 103.
[0004]
The wiring cable 125a of the swing motor 125 is installed through a path 107 provided along the rotation axis of the rotating arm. Similarly, the wiring cable 128a of the flange rotation motor 128 is installed on the rotation axis of the rotation arm, and further on the swing axis of the swing arm 103 from the housing portion 102b side.
[0005]
In this wrist mechanism, in order to install the wiring cable without exposing it to the outside, the turning arm 102 is bifurcated, and the drive system of the swing arm is placed on one side, and the wiring cable is placed on the other side. Therefore, the width dimension a of the wrist mechanism 1 is large. Further, the shape of the rotating arm 102 is complicated, and the number of parts increases. Furthermore, no consideration is given to the installation method of the wiring cable to the end effector (not shown) attached to the flange 104.
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and it is an object of the present invention to provide a compact industrial robot wrist mechanism that is easy to install a wiring cable, has a simple structure, and has a small number of parts.
[0007]
[Means for Solving the Problems]
The wrist mechanism of the industrial robot attached to the tip of the robot arm according to the present invention includes a pivot arm provided so as to be pivotable with respect to the robot arm, and a pivot arm provided so as to be pivotable with respect to the pivot arm. And a rotatable flange mounted on the swing arm. In this wrist mechanism, the rotation arm, the swing arm and the flange drive device are constituted by a reduction gear integrated motor in which a speed reduction mechanism is integrated, and the rotation arm, swing arm and flange are used as the corresponding motors. Each of the motors is directly connected, and each motor is provided with a through hole passing through the rotation axis thereof, and a wiring cable is passed therethrough.
According to this configuration, the drive system for each arm and flange is an independent unit that does not require a separate transmission mechanism, has a small number of parts, and is compact. In addition, since each arm and flange are directly attached to the motor, the connection structure is simple. Since the wiring routes of the cables are provided through each motor, a complicated special structure is not required for the wiring, and the wiring cables can be easily set up to the end effector at the hand.
[0008]
It is preferable to provide a protective sleeve in the through hole of the motor to prevent the wiring cable from being rubbed.
Moreover, it is preferable that a wrist mechanism has the cover of the wiring cable provided between two adjacent motors integrated with a reduction gear. By doing so, the exposure of the wiring cables is prevented, and damage to the wiring cables is prevented in an environment such as a welding robot.
[0009]
Furthermore, it is preferable to pass cables for supplying electric power, electrical signals, air, cooling water, and the like to the end effector attached to the flange through the through hole of the motor. In this case, it is not necessary to separately provide an installation route for these cables, and the wrist mechanism is more easily and compact in structure.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, the wrist mechanism 1 includes a rotation arm 2, a swing arm 3, a flange 4, and speed reducer integrated motors 21, 31, and 41 that integrally incorporate a speed reduction mechanism for driving them.
The motor 21 aligns the rotational axis with the longitudinal axis of the robot arm 11 and bolts the case 22 to the tip of the robot arm. The rotating arm 2 is connected to the speed reduction mechanism output shaft 23 of the motor 21 and is rotated with respect to the robot arm 11 by driving the motor.
[0011]
The rotary arm 2 has a shape in which a flange is attached to the body portion of the cylindrical case, and the flange is bolted to the output shaft 23 of the motor 21. The motor 31 is accommodated in the cylindrical case of the rotating arm 21 in a direction in which the rotation axis is orthogonal to the rotation axis of the motor 21. The motor 31 has its case 32 fixed to the cylindrical case of the rotating arm 2. The swing arm 3 is connected to the speed reduction mechanism output shaft 33 of the motor 31 and swings with respect to the rotating arm 2 by driving the motor.
[0012]
The swing arm 3 has a hollow portion protruding in the axial direction from the outer periphery of the cylindrical case, and the hollow portion is bolted to the output shaft 33 of the motor 31. The motor 41 is housed in the cylindrical case of the swing arm 3 with the rotation axis directed toward the hand. The motor 41 has its case 42 bolted to the cylindrical case of the swing arm 3. The flange 4 is connected to the speed reduction mechanism output shaft 43 of the motor 41 and is rotated by driving the motor.
[0013]
Thus, as shown in FIG. 1, the wrist mechanism 1 forms an in-line wrist in which the rotation axis of the flange 4 is aligned with the longitudinal axis of the robot arm 11.
This wrist mechanism can be modified to form an offset wrist. In this case, the swing arm 3 is attached to the motor 31 with its direction reversed from the state shown in FIG. That is, the opposite side of the hollow portion of the swing arm 3 is fixed to the motor 31 so that the cylindrical case of the swing arm 3 is disengaged from the longitudinal axis of the robot arm 11. An offset wrist can be easily realized by such a slight change.
[0014]
Further, the speed reducer integrated motors 21, 31, and 41 are provided with through holes 24, 34, and 44, respectively, at the centers of the rotation shafts. Correspondingly, an opening connected to the through hole 24 of the motor 21 is provided in the flange of the rotating arm 2. Similarly, an opening connected to the through hole 34 of the motor 31 is formed in the hollow portion of the swing arm 3. Further, the flange 4 also has an opening connected to the through hole 44 of the motor 41.
[0015]
Here, with reference to FIG. 3, the structural example of the reduction gear integrated motor used for this invention is demonstrated.
The example shown in FIG. 3 includes a motor unit 61, a harmonic drive speed reduction mechanism 62, and a cylindrical case 68 with a flange.
The motor unit 61 has the same configuration as that of a conventional AC motor, and is disposed in a case 68 serving as a stationary or stationary side portion of the motor together with a speed reduction mechanism 62 arranged coaxially with the motor unit.
[0016]
The speed reduction mechanism 62 includes a wave generator 64 connected to the output shaft of the motor unit 61, an output shaft 69 that is rotatably supported by a bearing 63 adjacent thereto, and a circular spline 65 formed on the inner peripheral wall of the case 68. The output shaft 69 has a flex spline 66 that enters between the wave generator 64 and the circular spline 65, and is driven by the motor unit 61 through these meshing.
The main bearing 63 is a cross roller bearing and can simultaneously support a radial load, a thrust load, and a moment load. As the main bearing, other bearings such as an angular ball bearing and a tapered roller bearing can be used instead of the cross roller bearing.
[0017]
The through hole 60 of the motor is formed on the rotation axis through the case 68, the rotation shaft of the motor unit 61 and the wave generator 64. A sleeve 67 is provided in the through hole 60. The sleeve 67 has one end fixed to the output shaft 69 of the speed reduction mechanism, and rotates at a low speed together with the output shaft 69.
[0018]
Referring again to FIG. 1, the wiring cable 7 to the wrist device 1 extends along the axis of the robot arm 11, passes through the through hole 24 of the motor 21, and enters the rotating arm 2. Next, a part 71 of the wiring cable 7 is connected to the motor 31, and the remaining cable passes through the through hole 34 of the motor 31 and enters the swing arm 3. In the swing arm 3, a part 72 of the wiring cable is connected to the motor 41. The remaining cable 73 passes through the through hole 44 of the motor 41 and the opening of the flange 4 and is connected to the end effector 5 attached to the flange.
[0019]
During the operation of the robot, the motors 21, 31, 41 rotate in the wrist mechanism 1, but the wiring cable 7 is covered with the sleeve 67 and is protected from rubbing accompanying the rotation.
Further, as seen in FIG. 1, the wiring cable 7 is covered with the robot arm 11, the rotating arm 2, and the swinging arm 3 and is not exposed to the outside. Therefore, the wiring cable 7 is protected from external causes of damage, such as sparks in a welding robot.
[0020]
According to the wrist mechanism of such an embodiment, the motor cable and the end effector cables can be installed through the through hole of the reduction gear integrated motor and each arm without being exposed to the outside.
Further, the connection between the pivot arm 2 and the swing arm 3 is a cantilever structure, the width a of the wrist mechanism is reduced, the shape of the structural member is simple, and the number of parts is reduced.
[0021]
As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited only to these specific forms, A various change can be added to embodiment mentioned above, or it can be set as another embodiment.
As an example, the speed reducer-integrated motor may use other speed reducing means such as an RV speed reducer, a cyclo speed reducer, or a planetary gear speed reducer instead of the above-described harmonic drive speed reducer. The reduction gear integrated motor may have a structure in which the motor unit and the reduction mechanism are housed in separate cases and the cases are coupled to each other. The through hole of the motor can be formed so as to pass working cables such as a welding cable in addition to the wiring cable. Further, the mounting relationship between the wrist mechanism 1 and the motor 3 in FIG. 1 may be reversed so that the motor output shaft is fixed to the robot arm and the motor case is fixed to the wrist mechanism casing.
[0022]
In the above embodiment, the pivoting and swinging arms are provided with a cylindrical case. However, these arms are replaced with, for example, L-shaped flat brackets, and one end portions thereof are fixed to the motor cases 32 and 42. Then, each motor may be supported. In this case, the wiring cable 7 is exposed to the outside between the motors 21 and 31 and between the motors 31 and 41. However, if necessary, a separate cover member is provided to cover the wiring cable. Can be protected.
[0023]
【The invention's effect】
The present invention uses a reduction gear integrated motor with a through-hole for rotational driving of the wrist mechanism, so that the drive system and the rotating shaft are made compact, and installation of a wiring cable is possible without providing an extra structure. . A drive unit using a reduction gear integrated motor has a small number of parts and high operation reliability. By adopting such a wrist mechanism, there is an effect that it is possible to provide an inexpensive industrial robot that is small, highly versatile, and reliable in operation.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a wrist mechanism of an industrial robot according to an embodiment of the present invention.
FIG. 2 is a schematic view showing a wrist mechanism of a conventional industrial robot.
FIG. 3 is a schematic sectional view showing an example of a reduction gear integrated motor used in the wrist mechanism of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Wrist mechanism 2 Rotating arm 3 Swing arm 4 Flange 7 Wiring cable 11 Robot arm 21, 31, 41 Reduction gear integrated motor 24, 34, 44 Through hole 60 Through hole 61 Motor part 62 Reduction mechanism 69 Output shaft

Claims (4)

A wrist mechanism for an industrial robot attached to the tip of a robot arm, a pivot arm provided so as to be pivotable with respect to the robot arm, and a pivot arm provided so as to be pivotable with respect to the pivot arm; In the wrist mechanism having a rotatable flange mounted on the swing arm,
The rotation arm, swing arm, and flange drive device are constituted by a speed reducer-integrated motor integrally incorporating a speed reduction mechanism, and the rotation arm, swing arm, and flange are directly connected to corresponding motors, respectively. In addition, a wrist mechanism for an industrial robot, wherein each motor is provided with a through-hole passing through the rotation axis thereof, and a wiring cable is passed therethrough. The wrist mechanism of the industrial robot according to claim 1, wherein a sleeve for protecting the wiring cable is provided in the through hole of the motor. The wrist mechanism according to claim 1 or 2, further comprising a wiring cable cover provided between two adjacent motors integrated with a reduction gear. 4. The wrist mechanism according to claim 1, wherein cables for supplying electric power, electrical signals, air, cooling water, and the like to the end effector attached to the flange are disposed through the through hole of the motor. Industrial robot wrist mechanism.

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