JP2003225883A - Joint part structure for robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a cable by preventing a direct contact between the cable and a frame of an arm. <P>SOLUTION: A frame 10 of a second arm 4 is rotatably connected to a connection part 8a of a frame 8 of a first arm 3 through a reducer unit 12 having a bearing 13. A wiring insertion hole 10b as a passage for the cable 7 is formed into a slit extended thin and long in a circular direction to be positioned on the left side in the illustration of the outer circumferential side of an installation cylinder part 10a of the frame 10 (connection part 8a), and a plastic outer cable guide 20 is provided on the wiring insertion hole 10b. An inner cable holder 21 to hold the cable 7 is supported in the outer cable guide 20 to be slidable in the circumferential direction. The inner cable holder 21 is protruded downward from the outer cable guide 20 disposed at a height corresponding to the connection part 8a of the frame 8. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention rotatably connects a frame of a second arm to a frame of a first arm via a shaft portion, and connects the frame of the second arm to an outer peripheral side of the shaft portion. The present invention relates to a joint structure of a robot which is provided with a wire insertion hole which serves as a passage for a cable.

[0002]

For example, in a multi-joint type robot in which a plurality of arms are rotatably connected in order,
Wiring (cable) is designed to pass through the inside of the arm. For example, in the joint portion of the first arm and the second arm in the small horizontal articulated robot, the frame of the second arm is rotatably connected to the frame of the first arm, and A cable (wiring) is passed through an insertion hole formed in the frame of the arm.

In this case, in order to prevent the cable from being pinched by the frame of the first arm and eventually being disconnected due to the relative rotation of the second arm with respect to the first arm, the insertion hole is circumferentially circled. It is considered that the cable has a long hole shape extending in an arc shape so that the cable can relatively move within the insertion hole. In this case, the rotation range of the second arm with respect to the first arm is regulated in terms of software and hardware. By being able to move, a relatively wide range of rotation can be secured.

However, even if the insertion hole is elongated as described above, the cable is not pinched, but the second arm rotates to the position where the insertion hole overlaps the frame of the first arm when viewed in the axial direction. Then, the cable may come into direct contact with the frame of the first arm made of metal (cast metal), so that the cable rubs and the coating is damaged,
If it gets worse, there is still a risk of disconnection.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a wiring insertion hole which is located on the outer peripheral side of a shaft portion and serves as a passage for a cable.
It is an object of the present invention to provide a robot joint structure capable of protecting the cable by preventing the cable from directly contacting the frame of the arm.

[0006]

In order to achieve the above object, in the joint structure of the robot of the present invention, the wire insertion hole provided in the frame of the second arm is formed in the shape of an elongated hole extending in the circumferential direction. At the same time, the cable is provided in a state in which the inside of the wiring insertion hole is held by the inner cable holder that is provided so as to be slidably movable in the circumferential direction, and according to the relative rotation of the second arm with respect to the first arm, The inner cable holder is configured to abut the frame of the first arm (the invention of claim 1).

According to this, the cable is passed through the wiring insertion hole while being held by the inner cable holder, so that the second arm is extended to the position where the wiring insertion hole overlaps the frame of the first arm. Even if the arm rotates, it is possible to prevent the cable from directly contacting the frame of the first arm by merely bringing the inner cable holder into contact with the frame of the first arm. Further, even when the inner cable holder comes into contact with the frame of the first arm, the inner cable holder relatively slides in the elongated wire insertion hole while holding the cable, thereby It is possible to secure a required rotation range of the first arm with respect to the first arm.

Therefore, according to the joint structure of the robot of the first aspect, the cable is prevented from directly contacting the frame of the first arm while the function required for the wiring insertion hole is secured. Can be protected, and a simple structure of providing an inner cable holder can be sufficient. It should be noted that the first arm in the present invention means one arm and the second arm means another arm that is rotatably connected to the arm, and a specific position in the entire robot arm. Of course, it does not indicate an ordinal arm.

In this case, the wiring insertion hole is provided with an outer cable guide formed in a cylindrical shape curved in an arc shape from the plastic along the direction in which the wiring insertion hole extends, and the outer cable guide is made of plastic. The inner cable holder may be slidably supported (the invention of claim 2). According to this, the sliding movement is performed by the sliding of the plastic members, so that the sliding movement of the inner cable holder is smoothly performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a small-sized horizontal multi-joint (4-axis) type robot will be described below with reference to the drawings. FIG. 4 shows an external configuration of the main body 1 of the horizontal articulated robot in this embodiment in a state in which it is at the origin position. First, the overall configuration of the robot main body 1 will be briefly described.

That is, on the base 2 fixedly installed on the installation surface of the equipment, the base end portion (right end portion in the figure) of the first arm 3 extending leftward in the figure rotates about the vertical axis J1. It is connected so that it can move (turn). A base end portion (a right end portion in the drawing) of a second arm 4 extending leftward in the drawing is connected to a top surface portion of the tip end of the first arm 3 so as to be rotatable (turnable) about a vertical axis J2. . At the tip of the second arm 4, a vertically extending shaft-shaped upper and lower arm 5 is provided so as to be vertically movable and coaxially rotatable. A tool such as a hand (not shown) is detachably attached to the tip (lower end) of the upper and lower arms 5.

Although not shown in detail, a uniaxial servomotor for rotating the first arm 3 with respect to the base 2 is provided in the base 2. At the same time, in the second arm 4, a biaxial servomotor 6 (see FIG. 1) for rotationally driving the second arm 4 with respect to the first arm 3 and a vertically moving arm 5 are provided. A Z-axis servo motor, a T-axis servo motor for driving the upper and lower arms 5 to rotate coaxially, and the like are provided.

A robot controller (not shown) is connected to the robot body 1 (base 2), and each of the motors is controlled by the robot controller. Therefore, in the robot body 1, as shown in FIG.
7 is passed from the base 2 through the first arm 3 and into the second arm 4.

Next, FIG. 1 and FIG. 2 show the structure of the joint portion connecting the first arm 3 and the second arm 4, particularly the second arm 4 portion, at the origin position of the robot body 1. The joint portion has the joint portion structure according to the present embodiment. In this case, the first arm 3 functions as the first arm according to the present invention, and the second arm 4 functions as the second arm according to the present invention. Hereinafter, this joint structure will be described in detail.

First, as shown in FIG. 1, the outer shell of the first arm 3 is composed of a metal (cast) frame 8 having a substantially thin box shape (hollow shape) as a whole. As shown in FIGS. 2 and 3, a substantially circular connecting portion 8a for connecting the second arm 4 is provided on the left end side of the upper wall portion of the frame 8. The left side and the front-rear part of the periphery of the connecting part 8a are open, and a constricted part 8b is formed on the right side of the connecting part 8a. The bottom wall of the left end of the frame 8 is open, and the opening is removable bottom cover 9
It is supposed to be blocked by.

On the other hand, the outer shell of the second arm 4 is made up of a box-shaped metal (cast) frame 10, and the upper surface thereof is covered with a removable upper cover 11. The biaxial servomotor 6 and the speed reducer unit 12 are incorporated in the right side portion of the frame 10 in the drawing. At this time, a cylindrical mounting cylinder portion 10a is integrally formed on the lower surface of the right end portion of the frame 10 in the drawing, corresponding to the connecting portion 8a, and the reduction gear is provided inside the mounting cylinder portion 10a. The unit 12 is incorporated, and the biaxial servomotor 6 is fixed to the upper end of the mounting cylinder 10a downward by bolting.

The speed reducer unit 12 is formed by integrating a bearing (cross roller bearing) 13 and a speed reducer, for example, a well-known harmonic drive, and has a wave generator 14 having a ball bearing on the outer circumference of an elliptical cam. A cup-shaped flexspline (elastic gear) 15 arranged on the outer circumference and a circular spline (internal gear) 16 meshing with the outer circumference are provided.

At this time, the wave generator 14
The rotary shaft 6a of the two-axis servomotor 6 is connected to the rotary shaft 6a, and the circular spline 16 is fixed to the mounting cylinder portion 10a of the frame 10 by bolting. A ring-shaped output shaft 18 as a shaft portion is connected to the tip (lower end) of the flexspline 15 via a mounting member 17. Further, in this case, the output shaft 18 also serves as an inner ring of the bearing 13, and two outer rings of the bearing 13 are fixed to the mounting cylinder portion 10a by bolting. An oil seal 19 is provided between the inner and outer races at the tip (lower end) of the bearing 13.

The output shaft 18 is fixed to the connecting portion 8a of the frame 8 of the first arm 3 by bolting. When the biaxial servomotor 6 is rotationally driven, the rotation is decelerated by the speed reducer unit 12 and transmitted to the output shaft 18. At this time, the output shaft 18 first arm 3 Connection part 8
By being fixed to a, the second arm 4 (frame 10) is rotated with respect to the first arm 3 in the directions of arrows A and B (see FIGS. 2 and 3) about the vertical axis J2. It will be.

The robot controller is provided with a so-called soft limit for restricting the range of rotation of the second arm 4 with respect to the first arm 3 in terms of software. The joint portion is provided with a mechanical stopper mechanism that mechanically restricts the rotation range of the second arm 4 with respect to the first arm 3. In this case, the rotation range restricted by the mechanical stopper mechanism (for example, 147.
8 °) is slightly larger than the rotation range regulated by the soft limit (145 ° on both sides from the origin position).

Now, as shown in FIG. 1 to FIG.
The frame 10 of the arm 4 is formed with a wiring insertion hole 10b, which is located on the left side in the figure on the outer peripheral side of the mounting cylinder portion 10a (the connecting portion 8a) and serves as a passage for the cable 7. In this case, the wiring insertion hole 10b has a certain depth (height) and is formed in an elongated hole shape (arc shape around the rotation axis of the second arm 4) elongated in the circumferential direction. ing. Further, as shown in FIG. 3B, the wiring insertion hole 10b is located at a position (axial direction) corresponding to the constricted portion 8b of the frame 8 when the second arm 4 rotates with respect to the first arm 3. It is formed at the position where it wraps when viewed at.

In the present embodiment, the wiring insertion hole 1
An outer cable guide 20 is provided at 0b, and an inner cable holder 21 is slidably supported by the outer cable guide 20. FIG. 5 shows the configuration of the outer cable guide 20 and the inner cable holder 21, of which the outer cable guide 20 is made of a plastic material (for example, polyacetal resin) and is a circle corresponding to the inner peripheral surface of the wiring insertion hole 10b. It is formed in a tubular shape curved in an arc shape. Further, as shown in FIG. 5B, the outer cable guide 20 is formed with a slide groove portion 20a extending in the lateral direction (circumferential direction) in a portion near the lower part of the inner wall surface before and after (inner outer peripheral side) thereof. Further, screw fastening portions 20b are integrally provided on both ends of the upper end portion.

On the other hand, the inner cable holder 21 is made of the same plastic material (polyacetal resin), curved in an arc shape along the inner peripheral surface of the outer cable guide 20, and has a cylindrical shape with a short dimension in the circumferential direction. Is formed in. The inner cable holder 21 has a size sufficient to allow the cable 7 to pass therethrough. In addition, as shown in FIG. 5B, the inner cable holder 21 is provided on the front and rear (inner and outer peripheral side) outer wall surfaces near the upper end.
Slide protrusion 21a that engages with the slide groove 20a
Are formed to extend in the lateral direction (circumferential direction).

As shown in FIG. 1 and the like, the outer cable guide 20 is adapted to be tightly fitted in the wiring insertion hole 10b and attached to the frame 10 by screwing. Then, the inner cable holder 2
In the state 1 in which the cable 7 is held inside, the slide protrusion 21a is engaged with the slide groove 20a so that the slide protrusion 21a is supported in the outer cable guide 20 so as to be slidable in the circumferential direction. Has become. At this time, as shown in FIGS. 1 and 5B, a part of the inner cable holder 21 is part of the outer cable guide 2.
0 (the wiring insertion hole 10b) is projected downward, and the projecting portion is arranged at a height position corresponding to the connecting portion 8a of the frame 8.

Thus, as will be described in the following explanation of the operation, the inner cable holder 21 holding the cable 7 is moved to the first cable by the relative rotation of the second arm 4 with respect to the first arm 3. Frame 8 of arm 3 (constriction 8
It comes into contact with b) and relatively slides in the outer cable guide 20. In this case, the outer cable guide 20 (wiring insertion hole 10b)
And the inner cable holder 21 corresponds to the second arm 4 described above.
Of course, it is formed in a size (position) corresponding to the rotation range of the first arm 3. Further, this rotation range is also secured largely by forming the constricted portion 8b in the frame 8 of the first arm 3.

Next, the operation of the above configuration will be described. In the joint structure for connecting the first arm 3 and the second arm 4 described above, the cable 7 is located outside the connecting part 8 a of the frame 8 of the first arm 3 and the frame 1 of the second arm 4.
The outer portion of the bearing 13 of No. 0 is passed between both arms 3 and 4. At this time, the outer cable guide 20 is provided in the wiring insertion hole 10b formed in the frame 10, and the cable 7 is The cable is passed through the outer cable guide 20 while being held by the inner cable holder 21.

Now, for example, when the second arm 4 is at the origin position, as shown in FIGS. 2 and 3 (a), the inner cable holder 21 and thus the cable 7 are connected to the outer cable guide 20 (wiring insertion hole 10b). It is located almost in the center. From this state, when the second arm 4 is rotated with respect to the first arm 3 in the direction of arrow B (counterclockwise direction when viewed from above), the frame of the first arm 3 is seen in the axial direction. 8 (constricted portion 8b) reaches the position where the wire insertion hole 10b (outer cable guide 20) wraps, and finally the inner cable holder 21 is provided on the side surface of the constricted portion 8b of the frame 8 as shown in FIG. 3 (b). Come into contact.

When the second arm 4 further rotates,
The inner cable holder 21 relatively slides in the outer cable guide 20 in the direction of arrow A while holding the cable 7. This allows the cable 7
However, it is possible to prevent the wire from being caught by the frame 8 of the first arm 3 and eventually broken. At this time, since both the inner cable holder 21 and the outer cable guide 20 are made of plastic, the inner cable holder 21 can be smoothly slid.

However, when the cable 7 may come into direct contact with the frame 8 of the metal (cast) first arm 3 during the operation of the second arm 4 described above, the cable 7 is rubbed and its coating is damaged. If it gets worse, there is a risk of breaking the wire. However, in this embodiment, since the cable 7 is held by the inner cable holder 21, the cable 7 does not come into direct contact with the frame 8 and is prevented from being scratched or damaged. The cable 7 is the second arm 4
The frame 10 does not come into direct contact with the edge of the wire insertion hole 10b.

Although not shown and described, the same action can be obtained when the second arm 4 rotates in the opposite direction (arrow A direction). Further, in the above configuration, the wiring insertion hole 10b
The (outer cable guide 20) has an elongated hole shape extending in the circumferential direction, and moreover, the constricted portion 8b is provided on the frame 8 of the first arm 3.
By providing the above, it is possible to secure a required rotation range of the second arm 4 with respect to the first arm 3. Since the wire insertion hole 10b is an elongated hole having a narrow width in the radial direction, it is possible to prevent the joint portion from becoming large in the diameter direction and to secure the strength of the frame 10.

As described above, according to the joint structure of the robot of this embodiment, it is possible to prevent the cable 7 from directly contacting the frame 8 of the first arm 3 in a state where the function required for the wiring insertion hole 10b is secured. The cable 7 can be prevented and protection of the cable 7 can be achieved, and the inner cable holder 21 can be simply added. Further, particularly in this embodiment, since the inner cable holder 21 is configured to slide on the inner surface of the same plastic outer cable guide 20, there is an advantage that the inner cable holder 21 slides smoothly. You can

In the above embodiment, the present invention is applied to the horizontal articulated robot, but the present invention can be applied to not only vertical articulated robots but also robots of various structures. In this case, the first arm and the second arm according to the present invention
The above-mentioned arm means one arm and another arm that is rotatably connected to that arm, and it goes without saying that the arm does not indicate a particular position or order in the entire robot arm. In addition, various modifications can be made to the shape of the arm (frame) of the robot, the arrangement of servo motors, the configuration of the bearings and the speed reducer, and so on. It can be implemented by appropriately changing it.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a vertical cross-sectional front view showing a configuration of a joint portion of a connecting portion between a first arm and a second arm.

FIG. 2 is a top view of a second arm showing a part of the upper cover in a cutaway manner.

FIG. 3 is a bottom view showing a state in which the second arm is at the origin position (a) and a state in which the second arm is rotated with respect to the first arm (b) with the lower cover removed.

FIG. 4 is a front view showing the appearance of the robot body.

FIG. 5 is a perspective view (a) and a vertical sectional view (b) showing a state where an inner cable holder is held by an outer cable guide.

[Explanation of symbols]

In the drawings, 1 is a robot body, 3 is a first arm (first arm), 4 is a second arm (second arm), 7 is a cable, 8 is a frame, 8a is a connecting portion, 8b is a constricted portion, 1
0 is a frame, 10b is a wire insertion hole, 12 is a speed reducer unit, 13 is a bearing, 20 is an outer cable guide, and 20a
Is a slide groove, 21 is an inner cable holder, and 21a is a slide protrusion.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Kito             4-12 Toranomon, Minato-ku, Tokyo Toranomon             4-chome Mori Building No.2 Denso Co., Ltd.             In the wave (72) Inventor Hidekazu Wakita             4-12 Toranomon, Minato-ku, Tokyo Toranomon             4-chome Mori Building No.2 Denso Co., Ltd.             In the wave F-term (reference) 3C007 BS15 CY00 CY02 CY04 MS11

Claims (2)

[Claims] 1. A frame of a second arm is rotatably connected to a frame of a first arm via a shaft portion, and
A joint structure of a robot in which a wiring insertion hole, which is located on the outer peripheral side of the shaft portion and serves as a passage for a cable, is provided in a frame of the second arm, wherein the wiring insertion hole extends in a circumferential direction. The cable is formed in a long hole shape, and the cable is provided so as to be slidable in the circumferential direction inside the wiring insertion hole, and the first arm is rotated according to relative rotation of the second arm with respect to the first arm. The joint structure of the robot, which is provided in a state of being held by an inner cable holder that abuts on a frame of the arm. 2. The wire insertion hole is provided with an outer cable guide formed in a cylindrical shape that is curved in an arc shape from a plastic along a direction in which the wire insertion hole extends, and the plastic is provided in the outer cable guide. 2. The joint structure of the robot according to claim 1, wherein the inner cable holder made of aluminum is supported so as to be slidable.