JPS5918193B2 - Robot arm lightening device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a robot arm that is operated by human power, and which memorizes and reproduces the movement trajectory, and in particular reduces the operating force during manual operation to achieve accurate positioning and teaching operations. The present invention relates to a new configuration of an arm rolling device that can be simplified.

Taking an industrial robot, for example, an articulated robot, as shown in FIG. Balancing was the usual practice.

That is, one point of the Z run sync plate 3 connected to the link 4 parallel to the axis of the vertical arm 1 and one point of the tip of the horizontal arm 2 are elastically connected by the screw 5. The balance of weight was achieved by

Furthermore, the combined weight of vertical arm 1 and horizontal arm 2 is
Balance was achieved using Kune 6, and the amount of unbalance in that case was reduced as much as possible. However, with such means, even though it is theoretically possible to completely balance the weight of each arm with a wedge, it is virtually impossible, especially for vertical arms. 1
Since the sliding part has a larger load than the horizontal arm 2, the amount of unclamping inevitably increases.

In addition, the mechanism that balances the weight of the arm is as described above.
Various systems other than the wedge-balanced type have been proposed, but all of them have more complicated structures than the mechanism shown in Figure 1, which increases the manufacturing cost of the machine and requires maintenance. It was also difficult to manage.

In view of the fact that conventional arm lightening devices have their own advantages and disadvantages, and that there is still no device that can reliably guarantee weight reduction at any arbitrary position of the arm, the present invention has been developed. The present invention was designed to provide a robot arm lightening device with a new structure that not only can fundamentally eliminate these drawbacks, but also achieves cost reduction and ease of operation due to its simple structure. The details thereof will be described below with reference to embodiments shown in the accompanying drawings.

Before referring to the specific structure of the device of the present invention, the force required to drive a commonly used robot arm consisting of a vertical arm 1 and a horizontal arm 2 is as follows. In other words, when a force is applied in a direction perpendicular to each arm at the end of each of the horizontal and vertical arms, the force that each arm starts to drive, in other words, each arm exists in a proportional relationship with this force. Assuming that the driving resistance of is ±R, , ±R (see Figure 1), the force F1 required to drive the horizontal arm 2 at the zero point at the tip of the horizontal arm 2 and the force F1 required to drive the vertical arm 1 by 1. The required force F2 is as follows.

However, F4 is a component force of F2 in a direction parallel to arm 2, and is obtained from F2·COs(90−η).

Further, η is the crossing angle between arms 1 and 2.

(A) and (C) From both formulas, the force F required to drive horizontal arm 2 and vertical arm 1 at the same time at the tip of horizontal arm 2
Here, it is impossible to make the driving resistance of each arm 1, 2 zero as long as there is sliding resistance at the connecting part of each arm and link, and usually the driving resistance of R, , R2 common number K9 is Resistance arises.

In particular, due to the arm weight load, the driving resistance of the vertical arm 1 is greater than the driving resistance of the horizontal arm 2, and the ratio is approximately 1:2 to 3. It is normal.

Also, as is clear from equations (c) and (d), when horizontal arm 2 drives vertical arm 1 by force in a parallel direction, the driving resistance is the force between horizontal arm 2 and vertical arm 1. It is influenced by the intersection angle (η) and is proportional to the reciprocal of a sine function with a minimum value of η=900. For example, when η=300, the driving force of the vertical arm 1 reaches twice as much.

If the driving force of the vertical arm 1 can be made zero in this way, it is inevitable that the force required to drive the entire arm is only R. If it is possible to bring the horizontal arm 2 into a complete or nearly perfect clamped state using a clamping system that combines the mechanism, the combined driving force of the arm consisting of the vertical arm 1 and the horizontal arm 2 should be as low as 2K9 or less. be able to. This greatly reduces the teaching workload.

The present invention has been made based on the above-mentioned technical background, and an example of its structure will be explained below using an implementation device shown in FIG. 2. The figure shows an arm portion of a robot such as a welding robot. This robot arm has a base pivoted on the upper surface of a base 9 with respect to a turntable 10 that rotates on a horizontal plane, and a vertical arm 1 that can move up and down in the vertical direction, and this vertical arm 1. It consists of a horizontal arm 2, which is attached to the tip of the horizontal arm 2 and whose tip can also be lifted up and down in the vertical direction.

Both arms 1 and 2 are provided with parallel links 4-1 and 4-2 and a sink plate 3 arranged in parallel to each arm, and a jig holding plate 11 that is attached to the tip of the horizontal arm 2. The absolute inclination with respect to a reference plane, for example, the ground, is always kept constant regardless of variations in the angle of elevation of both arms 1 and 2.

Both arms 1 and 2 are provided with a vertical arm driving cylinder 8 and a horizontal arm driving cylinder L, each having a position detector, as driving sources. In the robot configured as described above, the operator grasps the jig holding plate 11 and inputs teaching data, and the movement locus is read by the position detectors of both cylinders 7 and 8, and then stored in the memory to perform the work. During execution, playback can be performed according to this stored information, and this robot is equipped with a lightening device according to the present invention. The lightening device is connected to the vertical arm and the driving cylinder 8 via a fluid pressure circuit in order to control the vertical arm 1 in a desired direction of movement, and is attached to the jig holding plate 11 at three positions. Directional control valve, e.g. four-way switching valve 1
2, and a teach handle 13 which is attached to the rotation axis of the switching valve 12 so as to be swingable according to the arm movement direction.

The light actuation device having both of the above elements 12, 13 further includes a solenoid valve 14, a pilot check valve 15, 16, 1
7, 18, check valves 19, 20, and a servo valve 21 as accessory equipment, and the cylinder 8, the four-way switching valve 12, the teaching handle 13, and the above-mentioned fluid pressure accessory equipment as shown in the figure. A fluid pressure circuit such as the one described above is formed.

The structures of the four-way switching valve 12 and the teaching handle 13 are as shown in FIGS. 3 to 5.
When the teaching handle 13 is engaged with the shaft 23 that is integral with the spool 22 that rotates within the main body 22 of the four-way switching valve 12, and the teaching handle 13 is placed in the hanging neutral position as shown in the figure, four Port PS, R,
When all ports Cl and C2 are closed and the teaching handle 13 is turned at an acute angle clockwise in FIGS. 1 and 3 from this neutral position, ports P8 and C2 are closed.
2. Port R and port C1 are made to communicate with each other, and when turned counterclockwise at an acute angle, the port Ps and port C, and port R and port C2 are made to communicate with each other. .

When fixing the four-way switching valve 12 and the teaching handle 13 to the jig holding plate 11, the operating point of the jig (not shown), which has been removed in advance, and the tip gripping portion of the teaching handle 13 set at the neutral position must be adjusted. It is necessary to position them so that they match.

The operation of the arm lightening device having the above configuration will be explained next.

When the robot performs teaching, remove the jig, attach the four-way switching valve 12 and the teaching handle 13 together to the jig holding plate 11 according to the above-mentioned procedure, and then attach the solenoid valve. 14 to the A position, grasp the tip of the teaching handle 13, and push it forward. Pressure fluid flows through the solenoid valve 14 → port Ps → port C2 → pilot check valve 18 and then into the cylinder 8. The cylinder 8 expands as it is guided toward the head side.

Further, the pressurized fluid on the rod side of the cylinder 8 flows into the tank side R via the pilot check valve 17→port C1→port R→check valve 80. Therefore, the vertical arm 1 moves downward and the horizontal arm 2 moves forward following the movement of the teaching handle 13. and horizontal arm 2
As the teaching handle 13 moves forward, the inclination of the teaching handle 13, which had been held at a predetermined position, gradually returns to its original position, and when the original neutral hanging state is reached, the four-way selector valve 12 becomes neutral, and the rod extension of the cylinder 8 is stopped. It becomes possible to easily move the arm to a desired position using only the total amount of the rotational operation of the teaching handle 13 and the driving resistance of the horizontal arm 2.

However, the horizontal arm driving cylinder 7 is left in a free state throughout the above operation.

On the other hand, when the teaching handle 13 is pulled rearward, the cylinder 8 is shortened by forming a path opposite to the above-described fluid pressure path.

When the desired teaching work is performed by repeating the above operations, the vertical arm 1 is driven by fluid pressure by the teaching handle 13, so that the teaching work load is reduced to the handle 1.
Since the rotational torque of 3 is difficult to see, only the horizontal arm 2 drive resistance is required, and the robot arm can be operated extremely easily.

During the teaching work, the position detectors of the driving cylinders 7 and 8 of the horizontal arm 2 and the vertical arm 1 detect the current positions of the respective driving cylinders 7 and 8, and the positions are memorized.

On the other hand, during reproduction, the teaching trajectory can be reproduced by switching the solenoid valve 14 to the mouth position side and controlling the memorized position by the servo valve 21.

In this case, it is natural that the pilot check valves 17 and 18 are closed and the pilot check valves 15 and 16 are opened to form a normal fluid pressure circuit. All you have to do is remove the handle 13 and replace it with a jig.

In the above example, it is preferable for handling that the teaching handle 13 is formed into a return type lever that holds the tip in a free state at the neutral swing position. The teaching operation can be performed extremely easily by linking the operation section and the teaching handle 13 so that the swing neutral position and the neutral position of the directional control valve 12 match. In addition, the illustrated example above is a directional control valve 1
2 and the teaching handle 13 are in direct mechanical communication, but the present invention is not limited to such a structure; for example, the directional control valve 12 may be fixed at an appropriate position on the robot, and the teaching handle 13 may be directly connected to the teaching handle 13. A switch is attached to the tip of the horizontal arm 2, and a changeover switch is mechanically connected to the teaching handle 13, while an electromagnetic changeover valve is used for the direction control valve 12, and this electromagnetic actuation part and the changeover switch are connected electrically. Of course, a form in which the structure is connected to the above is also possible, and this modification is also naturally included in the present invention.

As described above, in the teaching operation of the robot arm, the directional control valve 12 is actuated by manually moving the movable teaching handle 13 in the desired direction of movement of the robot, and the control valve 12VC operates. Since the arm of the robot is operated hydraulically, the load on the worker during teaching work is reduced to less than half, and the mechanical design and manufacturing of the robot also makes it easier to move parts with high drive resistance, such as the vertical arm. It is no longer necessary to strictly adjust the amount of the arm's pair of arms, which occupies the entire structure, and the structure becomes extremely simple.As a result, this greatly contributes to the reduction of design man-hours and the ease of assembly.

Furthermore, it is also possible to change the valve opening degree of the light movement directional control valve 12 in accordance with the degree of inclination of the teaching handle 13, and since the opening degree related to the fluid pressure circuit can be adjusted, fluctuations in the teaching bead can be prevented. Even if there is, the teaching load force can be kept constant regardless of this, and work efficiency is greatly improved.
The present invention is a robot arm lightening device that exhibits various excellent functions as a practical device.

[Brief explanation of the drawing]

Figure 1 is a schematic mechanical diagram of an arm in a conventional robot.
FIG. 2 is a schematic mechanical diagram illustrating the main structure of an arm and a fluid pressure circuit in a robot according to an embodiment of the device of the present invention, and FIG. 3 is a directional control valve of the lightening device in FIG. 2. FIG. 4 is a sectional view taken along the line AA in FIG. 3, and FIG. 5 is a sectional view taken along the line BB in FIG. 4.

Claims (1)

[Claims] 1. In a robot that performs teaching operations manually and memorizes and reproduces the movement trajectory, an on/off fluid pressure is applied between the arm and the drive actuator 8 in order to control the arm in the desired movement direction. The 3-position directional control valve 12 forming a circuit is replaced with a jig removably attached to the tip of the arm, and the operating point of the jig and the tip are made to match, allowing swinging according to the direction of arm movement. The teaching handle 13 is provided with a freely attachable teaching handle 13, and the teaching handle 13 and the operation part of the directional control valve 12 are connected to each other, and the tip of the teaching handle 13 is manually swung in a predetermined movement direction of the arm during teaching. By causing the direction control valve 12 to turn on and off with a direction change, and by turning the actuator 8 on and off under a set pressure, the arm is made to follow a predetermined movement direction. An arm lightening device characterized by: 2. The teaching handle 13 is a return type lever that holds the tip end in a free state at a swinging neutral position, and the swinging neutral position is aligned with the operating point of the jig, and the teaching handle 13 and the above direction are aligned. 2. The robot arm lightening device according to claim 1, wherein the control valve 12 is connected to the operating section by matching the swing neutral position with the neutral position of the directional control valve 12. 3. According to claim 1 or 2, the three-position directional control valve 12 is attached to the distal end of the arm with its operating portion mechanically connected to the base of the teaching handle 13. robot arm lightening device. 4. The arm light movement of the robot according to claim 1 or 2, wherein the three-position directional control valve 12 has its operating portion connected to the base of the teaching handle 13 via an electro-mechanical conversion mechanism. conversion device.