JPH08141970A - Tool attaching device for industrial robot - Google Patents

Abstract

PURPOSE: To enable an end effector to be attached to a wrist of a robot arm tip at high positioning precision by providing a floating mechanism wherein an oscillating supporting means and direct acting guiding means are combined with each other on a tool attaching device. CONSTITUTION: When external force is applied to a tool attaching bracket 24 or a tool, a tool attaching plate 20 and the tool attaching bracket 24 are oscillated against energizing force of a coil spring. Since a step part 20c is pressed and brought in contact with the contact part 18a by a coil spring 38, the attaching plate 20 is oscillated by taking both engaging points as the supporting point and so oscillated that a shaft 28 may be retreated in the direction of a wrist 12 through a spherical bearing 26. The operation of this shaft 28 is transmitted to a detecting part 34a through a detecting member 42 and detected by a limit switch 34. The operation of a robot arm is stopped by a robot controller. Accordingly, shock can be cushioned when an end effector collides with a work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to industrial robots, and more particularly to a tool mounting device having a floating mechanism for mounting an end effector on a robot arm tip in an industrial robot.

[0002]

2. Description of the Related Art Conventionally, it has been widely practiced to attach an end effector such as a sealing gun or a deburring tool to the tip of a robot arm of an industrial robot to automate the process. Such process automation is performed by teaching the operation of the robot arm of the industrial robot in advance and moving the end effector attached to the tip of the robot arm along a predetermined path. If the work attachment position or dimensions deviate from the predetermined positions or dimensions, or if an abnormality occurs in the sequence that regulates the robot arm operation, the end effector attached to the robot arm tip collides with the work or surrounding equipment, The end effector may be damaged.

In order to prevent this, conventionally, an end effector is attached to the tip of the robot arm via a tool attaching device having a floating mechanism. The floating mechanism of such a tool attachment device includes, for example, a linear guide for guiding the end effector in a predetermined linear direction, and an air cylinder for urging the tool,
Some are configured to press the end effector against a work with a predetermined pressing force. In addition, a floating mechanism including a mounting flange for mounting on the wrist flange at the tip of the robot arm, and a coil spring and a taper cone provided between the tool mounting member for mounting a tool, a mounting flange and a tool mounting member, and A floating mechanism is used in which the spaces are connected by a rubber spring.

[0004]

However, the conventional tool mounting device having the floating mechanism has the following problems. In a tool mounting device equipped with an air cylinder type floating mechanism, after a certain period of use, air leakage increases and it becomes impossible to support the end effector in a floating manner. For the floating mechanism that combines the coil spring and the taper cone,
Due to mutual interference of the taper cones, there is a problem that the floating mechanism does not operate smoothly.For the floating mechanism equipped with a rubber spring, the rubber spring is special and expensive, and the robot posture Depending on the orientation of the end effector when it changes, the rubber spring is deformed by the gravity acting on the end effector, and accurate positioning cannot be performed.

The present invention has a technical problem to solve the above-mentioned problems of the prior art. The end effector is accurately positioned and attached to the tip of the robot arm, and a floating mechanism that operates smoothly is provided. It is intended to provide a tool mounting device.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a tool attachment device for attaching an end effector to the tip of a robot arm of an industrial robot, the attachment member for attaching the end effector to the tool attachment device, and the attachment member. An oscillating support means for oscillating support, a linear motion guide means for movably supporting the oscillating support means at a robot arm tip, and a mounting member for urging in a direction parallel to the straight line. The gist is a tool mounting device including a biasing means.

[0007]

The end effector attached to the attachment member is swingably held in the predetermined linear direction at the tip of the robot arm by the swing support means and the linear motion guide means. Since the urging means urges the mounting member in the linear direction, the mounting member supported by the swing support means is stable, and the mounting member or the end effector mounted on the mounting member collides with the work or peripheral equipment. When an external force is applied to the mounting member, the mounting member swings, and the linear motion guide means recedes in a predetermined linear direction against the urging force of the urging means to mitigate the impact generated from the impact. To be done. The above-mentioned swinging motion and retracting motion for cushioning the shock are
Since each of them is performed by the swing support means and the linear motion guide means, the operation is smooth.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. In FIG. 1, the tool attachment device 10 is an industrial robot, preferably an articulated robot (not shown).
Wrist flange 12a of the wrist 12 at the tip of the robot arm
Attached to. The wrist flange 12 is configured to rotate about the a1 axis passing through the center thereof. The tool attachment device 10 includes an attachment flange 14 for attaching to the wrist flange 12a. The mounting flange 14 has a shape in which one opening (the right end in FIGS. 1 and 2) of a hollow, generally cylindrical member is closed by a disc-shaped plate member. In order to attach the attachment flange 14 to the wrist flange 12a, a round hole may be appropriately formed in the plate-shaped member.

A generally disk-shaped support plate 16 is removably attached to the opening on the opposite side of the mounting flange 14 (the opening on the left end in FIGS. 1 and 2). A through hole 16b is formed at the center of the support plate 16. A linear guide 30 is provided in the through hole 16b as a linear motion guide means for slidably guiding and supporting the shaft 28 in a linear direction. The through hole 16b is preferably arranged such that its center is located on the a1 axis of the wrist 12, and
It is formed so as to extend in the a1 axis direction. As a result, the linear guide 30 extends along the a1 axis, and the shaft 28 is slidably supported in the left-right direction in FIGS. 1 and 2 along the a1 axis.

A detection member 42 is attached to the end of the shaft 28 on the side close to the wrist 12. On the other hand, a limit switch 34 as a motion detection sensor for the shaft 28 is provided in the internal space formed by the mounting flange 14 and the support plate 16. The detection member 42 and the limit switch 34 are
The detection member 42 is arranged so as to engage with the detection portion 34 a of the limit switch 34. Limit switch 34
Is electrically connected to a robot controller (not shown) that controls the robot to which the tool attachment device 10 is attached, and the shaft 28 moves from the position shown in FIG.
Movement in the direction of
The detection signal is transmitted to the robot controller.

A spherical bearing 26 as a swing support means is attached to the tip of the shaft 28 on the side away from the wrist 12 (the tip on the left side in FIGS. 1 and 2). The spherical bearing 26 is a well-known bearing including an inner ring and an outer ring,
The outer peripheral surface of the inner ring is composed of a part of a convex spherical surface, the inner peripheral surface of the outer ring is formed of a part of a concave spherical surface complementary to the outer peripheral surface of the inner ring, and the inner ring and the outer ring are relatively It is a mechanical element configured to be swingable. As shown in the drawing, the spherical bearing 26 is provided with a shaft 28 by means of bolts 36 that penetrate the inner ring.
It is attached to the tip of. As used herein, the term "swingable" means capable of swinging in any radial direction from a certain center. For example,
In the spherical bearing 26 shown in FIGS. 1 and 2, the inner ring and the outer ring are
It is possible to relatively swing in any radial direction about the a1 axis. Further, the spherical bearing 26 is fitted into the center hole 20a of the tool mounting plate 20 with its outer ring. With this configuration, the tool mounting plate 20
Are swingably supported by the inner ring of the spherical bearing 26, that is, the shaft 28.

The tool mounting plate 20 is a member formed by combining large-diameter and small-diameter, generally disk-shaped members, and a step portion 20c is formed therebetween. A substantially cylindrical housing member 18 is attached to the end surface of the support plate 16, and the large diameter portion of the tool attachment plate 20, the spherical bearing 26, the shaft 28, and the linear guide 30 are attached to the housing member 18. It is stored inside. Housing member 18
At the end opposite to the end attached to the support plate 16 (the end on the left side in FIGS. 1 and 2), a contact portion 18a that engages with the step portion 20c of the tool attachment plate 20 is provided. There is. Positioning means 44 is attached to the housing member 18 near the contact portion 18a. The positioning means 44 includes a positioning member 44 a having a conical tip, and the tip of the positioning member 44 a is a complementary recess 44 b formed on the end surface of the tool mounting plate 20.
By engaging (see FIG. 2), the tool mounting plate 20 is positioned in the circumferential direction.

Tool mounting plate 20 and support plate 16
A coil spring 38 as an urging means is disposed between and. Although one coil spring 38 is shown in FIGS. 1 and 2, preferably a plurality of coil springs 38 are provided.
Preferably, they are arranged at equal angular intervals on the same circumference with the a1 axis as the center. More specifically, the coil spring 38 is provided on the end surface of the tool mounting plate 20 facing the support plate 16.
Is provided with a concave portion 20a for receiving one end of the coil spring 38. On the end surface of the support plate 16 facing the tool mounting plate 20, a recess 16a is formed at a position facing the recess 20a, and the other end of the coil spring 38 is received in the recess 16a.
The spring constant of the coil spring 38 is equal to the tool mounting bracket 24.
It is appropriately selected according to the weight of the end effector attached to the.

In the illustrated embodiment, the recess 16a is formed so as to pass through the support plate 16 in parallel with the a1 axis, and the inner peripheral surface is formed with a threaded portion. Is appropriately positioned along the a1 axis so that the biasing force of the coil spring 38 can be adjusted. Tool mounting plate 20
Is urged by the coil spring 38 in a direction away from the wrist 12 in parallel with the a1 axis, and the contact portion 18a is abutted at the step portion 20c.
Is pressed against. At this time, the concave portion 44b is positioned in the positioning member 4
By engaging the tip of 4a, the tool mounting plate 20 is positioned in the circumferential direction about the a1 axis. On the other hand, the linear positioning of the tool mounting plate 20 around the a1 axis is maintained by the linear guide 28. Further, as shown in the drawing, when the wrist 12 is in the horizontal position, the positional deviation caused by the swing of the tool mounting plate 20 due to the weight of the end effector (not shown) mounted on the tool mounting bracket 24 is: It can be made smaller by appropriately selecting the spring constant of the coil spring 38 and adjusting the position of the screw 40 appropriately.

Further, on the end surface of the tool mounting plate 20,
A tool mounting bracket 24 is attached. Figure 1,
In FIG. 2, the tool mounting bracket 24 is illustrated as a generally L-shaped member as an example, but it is formed in an appropriate shape depending on the size and shape of the tool mounted on the tip of the robot arm. Therefore, the tool mounting plate 20 and the tool mounting bracket 24 include the spherical bearing 26 and the shaft 28.
The linear guide 30 supports the support plate 16 so that the linear guide 30 can swing in any radial direction around the a1 axis and can reciprocate in the linear direction along the a1 axis.

Next, the operation of the illustrated embodiment will be described.
As shown in FIG. 2, when an external force F acts on the tool mounting bracket 24 or a tool (not shown) mounted on the tool mounting bracket 24, the tool mounting plate 20 and the tool mounting bracket 24 are coil springs, specifically, ,
The coil spring oscillates in the direction of arrow A against the urging force of the coil spring arranged at a position not shown in FIG. More specifically, since the step portion 20c is pressed against the abutting portion 18a by the coil spring 38, the mounting plate 20 swings with the engagement point of the both as a fulcrum, and the shaft 28 is a1 through the spherical bearing 26. Swing back and forth along the axis in the direction of the wrist 12.

The movement of the shaft 28 is detected by the detection member 42.
Is transmitted to the detection unit 34a of the limit switch 34 via the, and detected by the limit switch 34. When the limit switch 34 detects the movement of the shaft 28, a detection signal is transmitted to the robot controller (not shown), and the robot controller stops the movement of the robot arm (not shown). Therefore, when an end effector (not shown) attached to the tool mounting bracket 24 collides with a work or peripheral equipment, the tool mounting bracket 24 and the tool mounting plate 20 swing and the impact generated from the collision. The movement of the robot is stopped before excessive force acts on the end effector, and damage to the end effector is prevented.

While the preferred embodiment of the invention has been described, it should be understood by those skilled in the art that this is merely an example and the invention is not limited thereto. For example, although the well-known spherical bearing has been described in the embodiment as the swing support means,
The swing support means can swing in any direction in order to swing the end effector or the tool mounting bracket when the end effector or the tool mounting bracket collides with the work or peripheral equipment, and to mitigate the generated impact. Any means will do. Therefore, as shown in FIG. 3, the rocking support means can also be constituted by a connecting element which is a combination of a spherical seat made of a concave spherical surface and a spherical end portion.

[0019]

As is apparent from the above description, since the tool attaching device according to the present invention is provided with the floating mechanism in which the swing support means and the linear motion guide means are combined, the operation is smooth. In addition, the end effector can be attached to the wrist at the tip of the robot arm with high positioning accuracy, particularly with high radial positioning accuracy. Also, when the end effector or tool mounting bracket collides with the work or peripheral equipment and the displacement of the end effector or tool mounting bracket exceeds a predetermined displacement amount, this is detected by the sensor and the robot controller uses the robot. The arm can be stopped to prevent damage to the end effector. Further, in the tool attaching device of the present invention, since the spherical bearing as the rocking support means and the linear guide as the linear motion guide means are housed in the housing, these elements interfere with the cable to the end effector or the air hose. There is nothing to do.

[Brief description of drawings]

1 is a cross-sectional view of a preferred embodiment of a tool attachment device according to the present invention.

FIG. 2 is a view similar to FIG. 1, showing the action when an external force acts on the tool attachment device.

FIG. 3 is a cross-sectional view showing another embodiment of the swing support means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Tool mounting device 16 ... Support plate 18 ... Housing member 20 ... Tool mounting plate 24 ... Tool mounting bracket 26 ... Spherical bearing as rocking support means 28 ... Shaft 30 ... Linear guide 38 as linear motion support means 38. Coil spring as a means

Claims (1)

[Claims] 1. A tool attachment device for attaching an end effector to a robot arm tip of an industrial robot, an attachment member for attaching the end effector to the tool attachment device, and a swing for swingably supporting the attachment member. A tool comprising a support means, a linear motion guide means for movably supporting the swing support means on the tip of the robot arm in a predetermined linear direction, and a biasing means for biasing the mounting member in a direction parallel to the straight line. Mounting device.