JPS6140514B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wrist mechanism for a robot, and more particularly to a wrist mechanism that swings and rotates and is capable of reliably locating its stop position.

Conventionally, in a robot wrist mechanism using a pneumatic rotary actuator, it is common to provide a stopper near the end of the rotation stroke to stop the rotation stroke, and it is not possible to stop the robot in the middle of the rotation stroke. Furthermore, with this method, it is impossible to maintain the stop position when the air pressure is cut off (see Japanese Utility Model Application No. 114276/1983).

In addition, in the case of a method in which a positioning plate with a tapered piece is pressed by a cylinder against a positioning plate with a taper pin fixed to the output shaft of an actuator, as shown in Japanese Patent Application Laid-Open No. 57-1691, the pin and piece are Positioning is possible only when the phases of the positioning plates with marks match exactly, and the problem is that the rotational speed of the pins and the timing of pressing the pieces are extremely difficult.

The present invention has been made with the aim of eliminating the above-mentioned drawbacks of conventional devices, and includes a claw support fitting fixed to the output shaft of a rotary actuator and a spring attached to the claw support fitting in the radial direction. The device includes a pair of claws that are slidably mounted under pressure, a stopper pin provided at a stop position, and a cylinder that moves the stopper pin in and out in a direction parallel to the output shaft, and both of the pair of claws are attached to the tips of the stopper pins. The stopper pin has an outwardly inclined portion, and the stopper pin abuts against the inclined portion of one of the pawls and pushes the pawl back against the spring, so that the stopper pin is held between the pair of pawls.

Embodiments of the present invention will be described below with reference to the accompanying drawings. A claw support fitting 3 fixed to an output shaft 2 of a rotary actuator 1 that can rotate in both forward and reverse directions has a pair of claws that slide in the radial direction. 4A, 4B are inserted, and this pair of claws 4A, 4B are connected to the spring 5.
It is pushed down in the radial direction by A and 5B. 6
A, 6B, 6C, and 6D are stopper pins provided at the stop position of the output shaft, and pneumatic cylinders 7A to 7D and pistons 8A to 8D are located at corresponding positions, respectively (only 7A, 7C, and 8A are shown in Fig. 1). (as shown).

In FIGS. 1 and 2, the claws 4A and 4B hold the stopper pin 6A and are in a stopped state. When air pressure is supplied to the cylinder 7A from this state, since the piston 8A is fixed to the case 10, the cylinder 7A moves to the left in the figure, moving the stopper pin 4A fixed to the rod cover 9 to the left, and thus the rotary Since the actuator 1 is in a free state, it can be rotated in both forward and reverse directions.If you want to stop the rotary actuator 1 at an arbitrary position, for example, at a position rotated 90 degrees clockwise in the state shown in Figure 2, you can supply air pressure to the rotary actuator 1. At the same time, when the stopper pin 6B at the 90° position is extended, the inclined part 4a provided outward at the tip of the left claw 4A (in the case of the opposite direction, the inclined part 4b similarly provided on the claw 4B) hits the stopper pin 6B. Pull the claw 4 on the right side against the spring 5A.
B hits the stopper pin 6B, and the rotation of the output shaft 2 is stopped. After that, the left claw 4A is the stopper pin 6.
Hold B in the sandwiched position from both sides by pressing down. Therefore, even if the air pressure of the rotary actuator 1 is cut off, the stopped position can be reliably maintained without rotating in the opposite direction.

Similarly, if you want to stop at a position rotated 180° or 270° from the state shown in FIG. (not shown) and 7C can be retracted to ensure a reliable stop in the same manner as described above.

As shown in FIG. 2, the claws 4A and 4B have tapered contact portions 4o and 4d with the stopper pins 6A to 6D so that the claws 4A and 4B always act in the direction of engagement with the stopper pins 6A to 6D. Therefore, it is possible to eliminate backlash due to changes in diameter due to processing errors of the stopper pins 6A to 6D, pin positional deviations, etc.

Although the above description has been made using four stopping points, any number of stopping points is possible.

Since the present invention is constructed as described above, arbitrary multi-point positioning can be performed by providing the stopper pin at the desired position, and by holding the stopper pin between both sides with claws, it is possible to securely hold the stopper pin when stopping. This has the effect that the stop position can be maintained even if the air pressure supplied to the rotary actuator is cut off. Further, by tapering the contact portion between the stopper pin and the pawl, there is an effect of preventing backlash at the stop position.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, partially shown in section, and FIG. 2 is a sectional view taken along line 2--2 in FIG. 1...Rotary actuator, 2...Output shaft,
4A, 4B...Claw, 5A, 5B...Spring, 6A, 6
B, 6C, 6D...stopapin.

Claims (1)

[Scope of Claims] 1. A pawl support fixture fixed to the output shaft of a rotary actuator, a pair of pawls slidably attached to the pawl support fixtures and biased in the radial direction by a spring, and a stop position. The stopper pin is provided with a stopper pin provided on one of the claws, and a cylinder for moving the stopper pin in and out in a direction parallel to the output shaft. A wrist mechanism for a robot, characterized in that the claw is pushed back against the spring when it comes into contact with the inclined portion and is held between the pair of claws. 2. The robot wrist mechanism according to claim 1, wherein the contact portions of the pair of claws with the stopper pin are formed in a tapered shape.