JPH07178693A - Cable holding structure in robot - Google Patents

Abstract

PURPOSE:To attain cable action copying moving a wrist by successively connecting annular holders with a cable inserted, and providing a plurality of guide rollers rollable in a direction of taking out and putting in the cable, in the case of wiring the cable in a tool mounted in the wrist of three- dimensionally changing an attitude. CONSTITUTION:In the peripheral surface of a wrist 3 of a robot, a holding unit 4 for making a cable follow-up, matched with moving an arm 2 and this wrist 3, is provided. This holding unit 4 is connected to the wrist 3 by a bracket 4a, to have two rods 6a, 6b supported to a bearing block 5 and opposed in a radial direction, and two holders 7, 8 are provided in a point end of each rod 6a, 6b. Each holder 7, 8 is provided with primary bearings 7a, 8a, based 7b, 8b fixedly fitted to an inner ring of the primary bearing, secondary bearings 7c, 8c fixed to each base 7b, 8b, etc., and the cable is supported through guide rollers 7e, 8e... to the secondary bearings 7c, 8c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable holding structure in which various wrist robots for industrial use can quickly move their wrists without interference between the arm wrists and signal cables.

[0002]

2. Description of the Related Art In an industrial robot equipped with a welding spot gun and various tools, wiring of a power electric cable, a signal electric cable, a cooling water hose, a power air hose, etc. is provided between a robot arm and a tool. It is necessary to install a pipe.

In such wiring, since the output shaft at the tip of the robot arm has a movable range around 360 ° around its axis, the wiring and piping between the robot and other peripheral devices do not interfere with each other. One of the challenges is

Further, since the tool is attached to the wrist of the robot at the tip of the arm, and this wrist also moves in a complicated manner, it is necessary to prevent the cable from interfering with the wrist and prevent the abrasion of the surface coating.

[0005] For example, Japanese Patent Laid-Open Publication No. 1-69330 discloses a device for preventing the cable from interfering with the arm and the wrist and keeping the cable in accordance with the movement of the wrist and the tool.

This is to provide a holder around the arm of the robot, which pivots coaxially, and to mount a rotary member having a rotation axis in the radial direction when viewed from the arm on the holder.
The cable is passed through the tip of the rotating member. By using such a rotating mechanism, even if the wrist makes a complicated movement, the cable can follow the movement and maintain the posture along the arm around the movement.

[0007]

However, since the holder is installed on the arm side of the robot, although it is located near the wrist, it follows the movement of the arm relatively well. Since this is unrelated to the arm, it cannot necessarily move like a wrist.
Therefore, the cable interferes with the wrist depending on the posture and the movement direction of the wrist, and the abrasion of the surface coating is unavoidable.

If the ability to follow the wrist is not sufficient, the cable is often pulled or entangled with the wrist or arm depending on the posture of the wrist. When such a state is repeated, the tension on the cable increases,
It may also cause the connector to come off.

Further, in order to eliminate the contact with the arm or wrist and the load of the excessive tension on the cable, the cable can be laid loosely with respect to the arm. However, when the arm rotates or swivels at a high speed, the cable is largely swung due to its own inertia, which easily causes an accident due to damage to the connector or interference with other devices.

As described above, in the conventional cable holding device, the ability to follow the movements of the arm and the wrist is still insufficient, which not only damages the cables and connectors, but also greatly affects the work by the robot.

An object to be solved in the present invention is to provide a cable holder capable of operating a cable in accordance with the movement of a robot arm or its wrist.

[0012]

According to the present invention, a robot is provided with a wrist which changes its posture three-dimensionally with respect to the axis of the arm, and a cable for a tool mounted on the wrist is wired from the arm along the wrist. In the above, the wrist is connected to an annular holder into which the cable is inserted, and the holder is provided with a plurality of guide rollers on its inner circumference that can be rolled in the inserting / removing direction of the cable.

In addition to being rotatable about its axis, the holder may be rotatable about its radial direction through its core. Further, it is possible to add a configuration in which the holder can be turned around a radial direction passing through the core, and the position of the core of the holder can be rotationally displaced with respect to the wrist.

[0014]

[Function] By arranging the guide rollers, which roll in contact with the inner circumference of the holder when the cable is inserted and removed, in an annular manner, the sliding resistance generated in front of the cable when the cable moves can be kept low. This enables smooth operation and prevents damage to the cable surface.

Further, by making the holder itself rotatable around its core or rotatable in the radial direction, the posture can be freely changed in response to twisting or change in direction of the cable. By allowing the position of the core of the cable to be rotationally displaced relative to the wrist, it is possible to perform a three-dimensional operation and follow the complicated movement of the cable.

Further, even when the two holders are provided and are arranged at appropriate intervals, the two holders are rotated around the center of rotation located between them so that they can be held against the wrist. At the same time, the position can be changed and the space surrounded by the guide rollers can be moved three-dimensionally. Therefore, the cable inserted into the annular row of guide rollers is held by the two holders while following the movement of the wrist.

Since the cable is inserted into the spaced holders, the cable is restrained at two points by the holder against bending movements of the wrist and twisting movements about the axis. If the distance between the constraining points, that is, the distance between the holders is set appropriately, the cable can be moved without being bent at an acute angle. Further, since the cable only comes into contact with the guide roller, the wear of the surface is prevented even if the cable is frequently moved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view showing a main part of a robot arm provided with a cable holding device of the present invention, and FIG. 2 is a line AA of FIG.
FIG. 7 is a side view of the main part showing the direction of the wrist as viewed from the direction of the arrow.

In the figure, a wrist 3 which is capable of three-dimensional movement is connected to the tip of an arm 2 which is held by a frame 1 of a robot and which is capable of turning up and down, left and right and around an axis. Various tools (not shown) are attached to the tip of the wrist 3, and a cable (described later) from the controller is connected to this tool.

The arm 2 and the wrist 3 are provided on the peripheral surface of the wrist 3.
The holding unit 4 is provided to move the cable in accordance with the movement of the cable. This holding unit 4 is connected to the wrist 3 by a bracket 4a, and FIG. 3 shows a cutaway view when viewed in the direction of FIG. 1 and FIG. 4 shows a bottom view of FIG.

The holding unit 4 includes a bearing block 5 provided at the tip of the bracket 4a, two rods 6a and 6b provided to face each other in the radial direction of the bearing block 5, and tips of these rods 6a and 6b, respectively. It is composed of two holders 7 and 8 provided.

FIG. 5 is a partial cutaway view of the holder 7 in the axial direction, FIG. 6 is a cutaway plan view of FIG. 5, FIG. 7 is a cutaway view taken along the line BB of FIG. 6, and FIG. FIG. 9 is a cross-sectional view taken along line C-C of FIG.

The holder 7 includes a rolling primary bearing 7a connected to the rod 6a, a base 7b fitted and fixed to the inner ring 7a-1 of the primary bearing 7a, a rolling secondary bearing 7c fixed to the base 7b, and Inner ring 7c of secondary bearing
1 and a guide roller 7e held by the mount plate 7d. As shown in FIG. 5, the plurality of guide rollers 7e are arranged in an annular shape on the inner peripheral side of the mount plate 7d, and are freely rollable when a cable comes into contact when the wrist 3 moves around.

In such a holder 7, the base 7b can be swung around its center in FIG. 6, and the mount plate 7d is swung around its center in FIG. 5 by the secondary bearing 7c fixed to this base 7b. Therefore, the annular row of the guide rollers 7e held by the mount plate 7d can change its posture three-dimensionally in FIG.

The other holder 8 has the same structure, and its movement with respect to the change of the posture of the cable is also the same. The same members as the holder 7 described above are designated by the reference numerals 8a to 8e in FIG. It is shown in parentheses.

FIG. 9 shows the holding unit 4 by the movement of the wrist 3.
FIG. 3 is a diagram showing the operation of FIG. 3 and is a side view seen from the same direction as FIG. 2.

FIG. 3A shows a state in which the wrist 3 is coaxial with the arm 2, and the line segment connecting the centers of the bases 7b and 8b of the holders 7 and 8 is the axes of the wrist 3 and the arm 2. It is arranged in parallel. When the tip of the wrist 3 is directed obliquely downward as shown in FIG. 6C, the position of the bearing block 5 held by the bracket 4a with respect to the wrist 3 does not change, and the rods 6a and 6b change their postures. The positions of the holders 7 and 8 at these tips are changed. At this time, the primary bearings 7a, 8a connected to the rods 6a, 6b
When no load is applied to the bearings, the posture as shown in FIG. 9A is maintained, but the secondary bearings 7c and 8c change their postures by the rotation of the bases 7b and 8b according to the external force and the inertia of the sharp turning.

Further, even when the posture of the wrist 3 is changed upward as shown in FIG. 2, the positions of the holders 7 and 8 are changed as shown in the drawing. Further, even when the wrist 3 rotates about its axis and twists with respect to the posture of the arm 2, the holding unit 4 changes its overall posture in accordance with the movement of the bracket 4a.

With respect to such movement of the wrist 3, the position of the contact point of the holding unit 4 with respect to the wrist 3 by the bracket 4a does not change, and the holder 7 is rotated by this contact point, that is, the rotation of the rods 6a, 6b by the bearing block 5. The positions of 8 are only changed. The distance between the centers of the holders 7 and 8 is the rod 6
It is kept constant by a and 6b, and it is possible to guide the cable with a constant space between the holders 7 and 8 regardless of the movement of the wrist 3.

10 and 11 are views showing a state in which the cable is attached.

The cable 20 in which a large number of wirings are bundled is held in the middle by a winding spring 21 suspended from the ceiling of the factory so that it does not interfere with the operation of the arm 2. The take-up spring 21 also serves to restrain unnecessary behavior of the cable 20 and maintain the posture along the arm 2 and the wrist 3.

The cable 20 is composed of annular mount plates 7d and 8d of the holders 7 and 8 of the holding unit 4, respectively.
, And the tip thereof is connected to a tool (not shown) attached to the wrist 3. At this time, since the cable 20 is surrounded by the guide rollers 7e arranged in an annular shape, when the cable 20 moves in the longitudinal direction, the peripheral surface of the cable 20 contacts the guide rollers 7e and 8e, and the guide rollers 7e and 8e.
Friction on the surface of the cable 20 is reduced by rolling e and 8e.

In FIG. 11 (b), when the wrist 3 twists counterclockwise around its axis, the cable 20 in the portion restrained by the holders 7 and 8 is also wound around the wrist 3. become. At this time, the holders 7 and 8 receive the external force which changes the posture of the cable 20, and change their positions as shown in FIG. The positions of the holders 7 and 8 are changed by turning the rods 6a and 6b around the bearing block 5 and mounting plates 7d and 8d.
It is possible by composition such as changing the posture of the
This causes the cable 20 to follow the movement of the wrist 3. Since the cable 20 is pulled toward the wrist 3, the winding spring 21 allows such movement of the cable 20 and extends as shown in FIG. Therefore,
A constant tension is applied to the cable 20 irrespective of the posture change of the wrist 3, and a large whirling of the cable 20 is prevented even when the arm 2 suddenly moves.

In the above structure, the cable 20 is shown in FIG.
0 and FIG. 11, it is held by two holders 7, 8 which are spaced from each other, these holders 7,
8 is surrounded by a guide roller 7e provided on the inner circumference. For this reason, even when the wrist 3 changes its posture in various ways and the cable 20 moves around in its longitudinal direction, the guide roller 7e rotates, so that the cable 20 is prevented from being worn due to the surface contact, and the durability of the cable 20 is improved. Also,
The portions restrained by the holders 7 and 8 do not contact the cable 20 to increase the tension of the cable 20, and the operation of the arm 2 is not affected.

Since the holders 7 and 8 can freely change their postures in the axial direction by the bearing block 5 and the first bearing 7a, and in addition, the holders 7 and 8 can rotate about the axis by the secondary bearing 7c. The cable 20 can be made to follow various movements of the wrist 3. At this time, even if the postures of the holders 7 and 8 are changed so that the angles formed by the respective axes become acute angles, the holders 7 and 8 still have an appropriate distance, so that the holders 7 and 8 have a proper distance. The cable 20 does not bend sharply at the portion. Therefore, even if the robot has a wrist 3 that moves around violently, the cable 2
It is possible to suppress the fatigue of 0 and withstand long-term use.

12 and 13 are views showing only a holding unit showing another example.

In the figure, the bearing block 5 shown in FIG.
1 is provided, and the bearing block 10 is connected to the wrist 3 via the bracket 4a shown in FIG.

A rod 10b parallel to the rotation axis of the bearing block 10 is connected to the outer ring 10a that rotates coaxially with the bearing block 10, and a holder 11 is connected to this rod 10b. This holder 11 is similar to the previous example in that the primary bearing 11a of the primary bearing 11a connected to the rod 10b is
a base 11 fixedly fitted into the inner ring 11a-1 of a
b, a secondary bearing 11c fixed to the base 11b, a mount plate 11d connected to an inner ring 11c-1 of the secondary bearing 11c, and a guide roller 11e held by the mount plate 11d.

Even in such a structure, as shown in FIGS. 10 and 11, by passing the cable 20 through the holder 11, the cable 20 is guided by the guide roller 11e.
Even when the wrist 3 changes its posture in various directions and the cable 20 moves around in its longitudinal direction, the guide roller 7e rotates, so that the wear of the cable 20 due to the surface contact is prevented and the durability of the cable 20 is improved. .

[0040]

The present invention has the following effects due to its structure.

1) By providing the holder on the wrist,
The cable can be held so as to follow the movement of the wrist with respect to the complicated movement of the wrist, and the followability to the movement of the wrist is improved and the robot can be operated with less influence of inertia.

2) Since the holder is provided with the guide rollers, even if the cables move around frequently and come into contact with these guide rollers, the guide rollers rotate to prevent the cable surface from being worn due to the contact. Durability is also greatly improved.

3) By arranging the two holders at a distance, even if the bending angle and the twisting angle of the wrist are large,
The cable can be held without being bent at an acute angle, and there is no accident such as cable breakage.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part showing an arm portion of a robot provided with a cable holding structure of the present invention.

FIG. 2 is a side view of an arm portion when FIG. 1 is viewed in the direction of arrow AA.

FIG. 3 is a cutaway side view of a holding unit.

FIG. 4 is a bottom view of the holding unit shown in FIG.

FIG. 5 is a cutaway view of the holder as viewed in the axial direction.

6 is a cutaway plan view of the holder of FIG.

FIG. 7 is a cutaway view taken along the line BB of FIG.

8 is a cross-sectional view taken along the line CC of FIG.

9A and 9B are diagrams showing the operation of the holding unit according to the movement of the wrist at the tip of the arm, and FIG. 9A is a side view when the axis of the wrist coincides with the axis of the arm, and FIG. (A) is a front view of the same figure (a) seen from the wrist side, and (c) of the same figure is a side view when the wrist is bent.

FIG. 10 is a side view of a main part when a cable is passed through the holding unit.

11A and 11B are views showing changes in the posture of the holding unit due to the movement of the wrist when the cable is passed through, where FIG. 11A is a side view of a main part, and FIG. It is the front view which looked at a) in the direction of an axis of a wrist.

FIG. 12 is a bearing block 10 attached to the wrist of the robot.
It is a partially cutaway view showing an example in which a single holder is provided.

FIG. 13 is a partially cutaway view showing the example of FIG. 12 when the secondary bearing is rotated by 90 °.

[Explanation of symbols]

1 frame 8 holder 2 arm 8a primary bearing 3 wrist 8b base 4 holding unit 8c secondary bearing 4a bracket 8d mount plate 5 bearing block 8e guide roller 6a rod 20 cable 6b rod 21 winding spring 7 holder 7a primary bearing 7b base 7c two Secondary bearing 7d Mount plate 7e Guide roller

Claims (4)

[Claims] 1. A robot having a wrist that changes its posture three-dimensionally with respect to the axis of the arm, and a cable for a tool mounted on the wrist is wired along the wrist from the arm, wherein the cable is attached to the wrist. A cable holding structure for a robot, in which an annular holder into which a cable is inserted is connected, and the holder is provided with a plurality of guide rollers on its inner circumference that can roll in the inserting / removing direction of the cable. 2. A robot having a wrist that changes its posture three-dimensionally with respect to the axis of the arm, and a cable for a tool mounted on the wrist is wired from the arm along the wrist, wherein the cable is attached to the wrist. A cable holding structure for a robot, in which an annular holder into which is inserted is connected, and the holder is connected to the wrist so as to be rotatable about its axis. 3. A robot having a wrist that changes its posture three-dimensionally with respect to the axis of the arm, and a cable for a tool equipped on the wrist is wired along the wrist from the arm, wherein the cable is attached to the wrist. A cable holding structure for a robot, in which an annular holder into which is inserted is connected, and the holder is rotatable about its axis and rotatable about a radial direction passing through a core. 4. A robot having a wrist that changes its posture three-dimensionally with respect to the axis of the arm, and a cable for a tool mounted on the wrist is wired along the wrist from the arm, wherein the cable is attached to the wrist. Is connected to an annular holder, the holder is rotatable about its axis and rotatable about a radial direction passing through the core, and the position of the core of the holder is rotated with respect to the wrist. A cable holding structure for a robot that can be displaced.