JPS6328751B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a hand for an industrial robot, and more particularly, it is possible to accurately and easily position a workpiece held by the hand for release. It is about the mechanism.

``Prior art'' A manipulator that performs the functions of the human upper limb is
It is used as an industrial robot in various industrial fields, and is particularly suitable for inserting workpieces such as parts and other assembly work on product assembly lines.

Problems to be Solved by the Invention However, in order to set the work toward a predetermined assembly position after holding the work by the hand of an industrial robot, it is necessary to perform accurate positioning control. For this purpose, various sensors are installed in the robot hand to give it sensory and recognition functions (so-called intelligent robots), and positioning conditions and other information are converted into numerical commands, and high-precision robots that operate faithfully to these commands are developed. Providing a servo function (so-called numerically controlled robot) has been proposed and implemented as a solution. and,
Highly accurate positioning can be achieved by making the robot perceptual or numerically controlled in this way, but this also complicates the robot mechanism and increases equipment costs. Despite the strong demand for this, the reality is that it has become economically difficult to introduce it into any assembly production line.

One proposal to solve this bottleneck with a mechanical structure is disclosed in Japanese Utility Model Application Publication No. 53-108082 as a "handling device for inserting articles", which is When inserting the article 7 into the perforated hole 13', the article 7 needs to come into contact with the guide piece 9 and push it apart, since the guide piece 9 is not structured to actively expand. (See Figure 6 C and D). For this reason, if the article 7 is soft, there is a risk that it may be deformed or damaged by forcibly abutting against the guide piece 9, and there is a drawback that the products that can be handled are limited.

Purpose of the Invention The present invention was devised in view of the above-mentioned difficulties in the prior art, and an object of the present invention is to accurately and easily achieve release positioning of a workpiece held by a hand using a mechanical structure. shall be.

Means for Solving the Problems In order to overcome the above-mentioned problems and suitably achieve the intended purpose, the hand of the industrial robot according to the present invention is attached to the wrist provided at the tip of the arm of the industrial robot. a first linear actuator provided at the tip of the first movable member and having a first movable member capable of extending and retracting in the axial direction of the wrist; and a workpiece holder provided at the tip of the first movable member and detachably holding a desired workpiece. a second linear actuator that is disposed on the wrist and has a second movable member that can extend and retreat coaxially with the first movable member; and a second linear actuator that is located outside of the workpiece holding hand. , a plurality of guide members pivotally supported on the second movable member so as to converge and expand with respect to the axis of the wrist; a plurality of guide members formed to extend in the axial direction on the outer surface of the first movable member; a guide portion that cooperates with the plurality of guide members to convergently deflect the guide members slightly inward when the second movable member is extended under the biasing action of the two linear actuator; It is characterized by being composed of.

(Example) Next, the present invention will be described in detail by way of preferred examples and with reference to the accompanying drawings.

FIG. 1 is a partial longitudinal sectional side view showing a schematic configuration of a robot hand according to the present invention, and FIG. 2 is a cross sectional view taken along the line A--A in FIG. 1. In the figure, reference numeral 10 indicates an exterior casing fixed to the tip of an arm (not shown) of an industrial robot, and a wrist 12 is pivotally supported in the lower part of this exterior casing 10 so as to be horizontally rotatable. That is, the casing 10
As shown in FIG. 1, a cylindrical bush 14 made of metal impregnated with lubricating oil is inserted and fixed therein, and a sleeve 16 forming the wrist 12 is slidably and rotatably fitted into the inner surface of this bush 14. equipped. A flange 1 is provided at the top of the sleeve 16.
8 is formed and slidably abuts on the top surface of the casing 10, and a large diameter timing gear 20 is fitted and fixed on the outer periphery of the sleeve 16. This timing gear 20 has a casing 10
A timing belt 26 is stretched between a small-diameter timing gear 24 fixed to the rotating shaft of a servo motor 22 fixed to the outside of the servo motor 2.
The wrist 1 is moved against the outer casing 10 by the drive of 2.
2 is designed to rotate.

A first linear actuator 28 is disposed along the longitudinal direction of the outer casing 10 and the wrist 12 at the center axis thereof, and is adapted to apply an extending and retracting motion to the workpiece holding hand 30. The first linear actuator 28 may be any type as long as it imparts a linear motion of a predetermined stroke length to the hand 30, and may be a reciprocating cylinder using fluid pressure such as air pressure or oil pressure, or a motor-driven easy-to-actuate cylinder.
Pinion mechanisms and other linear motor mechanisms can be used depending on the design task. In this embodiment, a pneumatic cylinder is used as the first linear actuator. That is, a cylinder tube 32 is provided that passes through the center of the exterior casing 10 and the wrist 12 and extends a predetermined distance below the wrist 12. A piston rod 36, which functions as a movable member, is inserted therethrough. The bottom of a sleeve 40 loosely fitted around the outer periphery of the piston rod 36 is in contact with the cylinder bottom 38 fitted to the bottom of the cylinder tube 32. The length of the downward stroke is regulated to a predetermined distance. A compression spring 42 is elastically interposed between the piston head 34 and the cylinder bottom 38.
This spring 42 causes the piston rod 36 to return and rise after being lowered. The top of the cylinder tube 32 is provided with a port 44 for air intake, so the pneumatic cylinder is single-acting.

Furthermore, as shown in FIGS. 1 and 2, a plurality of grooves 46 are bored in the outer circumference of the cylinder tube 32 extending downward from the wrist 12 to function as a guide section in the longitudinal direction. Each of the grooves 46 has a taper 48 whose drilling depth gradually increases near the lower end of the cylinder tube 32. The roller 52 of the guide member 50 lands in this groove 46 and runs, imparting a convergent deflection action to the guide member 50, the details of which will be described later.

A hand 30 for holding a workpiece is fixed to the lower end of the piston rod 36. In this embodiment, the hand 30 has a vacuum cup 54, and performs vacuum suction and ejection of the workpiece by connecting a pipe body 58 connected to a negative pressure box 56 to an on-off valve and a vacuum source (not shown). . The workpiece holding function of the hand 30 is not limited to vacuum suction as shown in the drawings, but may also include electromagnetic suction using an electromagnet, or a gripping function using fingers or grippers. It goes without saying that the hand 30 may be provided with various degrees of freedom such as a sweep operation, a tilt operation, and a rotation operation with respect to the wrist 12.

Next, a second linear actuator 60 is arranged concentrically around the outer circumference of the first linear actuator 28.
is provided, so this will be explained below.
As with the first linear actuator 28, the second linear actuator 60 may be operated based on various operating principles, but in this embodiment, a single-acting pneumatic cylinder is employed. For example, in FIG. 1, the flanged sleeve 16 also serves as the cylinder tube of the second pneumatic cylinder 60, and is located inside the cylinder tube 16 and at the cylinder tube 32 of the first pneumatic cylinder 28.
A piston rod 62, which functions as a cylindrical second movable member, is concentrically inserted and arranged on the outside of the piston. A piston head 64 is fixed to the top of the piston rod 62, and the piston head 64 is in close contact with the outer surface of the cylinder tube 32 and the inner surface of another cylinder tube 16, and the lower end of the piston rod 62 has a flange. board 66
is fixed.

A cylinder bottom 68 is fitted to the bottom of the cylinder tube 16 of the second pneumatic cylinder 60,
A flanged sleeve 70 loosely fitted around the outer periphery of the piston rod 62 is supported upright on this bottom.
The length of the downward stroke of No. 2 is regulated to a predetermined distance. A compression spring 72 is elastically interposed between the piston head 64 and the flange portion of the sleeve 70, so that the piston rod 62 after being lowered can be elastically returned to the upper position. Note that a port 76 for air intake is opened in the cylinder head 74.

Next, a plurality of support members 82 are disposed on the lower surface of the flange plate 66 to swingably support a swing block 78 (to be described later) via a shaft 80 (the number of support members 82 is equal to This corresponds to the number of grooves 46 provided in the longitudinal direction on the outer periphery of the cylinder tube 32 of the cylinder 28, and is four in this embodiment). A roller 52 of a predetermined diameter is rotatably supported on each swing block 78, and the roller 52 is seated in the corresponding groove 46. Further, between the swing block 78 and the flange plate 66, there are compression springs 84 that press the swing block 78 inward to apply a deflecting force. It is interposed in. A guide member 50 made of a long plate is fixed to the outside of the swing block 78, and this guide member 50 extends downwardly outside the hand 30 without contacting it. Then, the groove 46
The rollers 52 that have settled therein, when the rocking block 78 is in the position shown in FIG.
The diameter of each guide plate 50 is set in advance so that the guide plate 50 is substantially parallel to the cylinder tube 32. Therefore, if the second pneumatic cylinder 60 is now energized to extend and lower the piston rod 62, each swinging block 78 will drop the roller 52 into the groove 46 and rotate it. (The guide members 50, 50 descend while maintaining a parallel relationship with each other.) When the roller 52 approaches the tapered portion 48 of the groove 46, the swing block 78 moves slightly inward under the pressure of the compression spring 84. begins to deflect,
It will be understood that the opposing guide members 50, 50 eventually converge toward each other.

The functions and effects of the industrial robot hand according to the present invention constructed as described above will be explained with reference to FIGS. 1 to 3. Assuming that an insertion operation is performed in which a part or other workpiece 88 is inserted into a mounting hole 90 of an object to be assembled on a product assembly line, an arm (not shown) rotates or runs into a workpiece accumulation pool, or extends or retreats. The workpieces 88 are held one by one by vacuum suction on the hand 30, and then, as shown in FIG.
is repeatedly raised and lowered by the horizontal rotation by the servo motor 22 and the action of the first pneumatic cylinder 28, but this operation will be omitted), but high-precision positioning is not required.

If the second pneumatic cylinder 60 is now pressurized, its piston rod 62 will extend and descend a predetermined distance from the cylinder tube 16. At this time, the flange plate 66 provided at the tip of the piston rod 62
As mentioned above, the swinging block 78 which is pivotally supported maintains the posture shown in FIGS. 1 and 3 while the roller 52 is running in the groove 46.
When the piston rod 62 extends a predetermined distance and the rollers 52 approach the tapered portion 48 of the groove 46, they begin to deflect inwardly under the pressure of the compression spring 84, ultimately causing the respective blocks 78 to be deflected. The fixed guide members 50, 50 will converge relatively to each other (see FIG. 3, 2). In this case,
The convergent lower ends of the guide members 50, 50 may be positioned so as to stop close to the opening of the mounting hole 90, or may be slightly inserted into the mounting hole 90 (not shown). .

Next, when the first pneumatic cylinder 28 is pressurized, the piston rod 36 extends and descends, allowing the workpiece 88 vacuum-adsorbed by the hand 30 to arrive directly above the mounting hole 90 (see FIG. 3). reference). Here hand 30 Bakyum cup 54
When the vacuum is released, the workpiece 88 is moved to the guide member 5.
It stably falls under its own weight into the mounting hole 90 while being guided laterally by the angles 0 and 50. After discharging the workpiece 88, the first and second pneumatic cylinders 2
8 and 60 operate separately, the hand 30 rises, and as the flange plate 66 rises, the guide members 50 and 50 begin to expand from the converged state, become parallel to each other, and return to their original position (first position). 3 Returning to Figure 1,
The suction operation for the next workpiece 88 begins.

Effects of the Invention As described above, according to the industrial robot hand according to the present invention, the hand itself holding the workpiece can
Even if the workpiece is not accurately positioned at the mounting hole or other desired position, the guide members convergently approach the vicinity of the position to form a guide path, and the workpiece is guided between the guide members in this converged state. Since the workpiece is released toward the destination while being moved, the result is that accurate positioning of the workpiece has been achieved. Furthermore, when holding a workpiece by suction using the vacuum cup, there is an advantage that it is not necessary to perform suction while strictly aligning the center of the workpiece, and it is sufficient to perform suction and holding with a certain degree of rough positioning. Moreover, since the purpose is achieved with a purely mechanical configuration without requiring a complicated servo follow-up mechanism or an expensive sensing function, the manufacturing cost is low and it can be widely used.

In the illustrated embodiment, the number of grooves and rocking blocks provided on the outer periphery of the cylinder tube is 4, respectively.
However, even if there are, for example, three, the structure is stabilized as a three-point support structure. Further, the guide member does not necessarily have to be fixed to each swinging block one by one, but it is sufficient if it is provided at least for each opposing block. In the illustrated embodiments, there are therefore two or four. Furthermore, although this embodiment has been described as a suitable example for use in workpiece insertion work on a product assembly line, etc., it can also be used for boxes, cartons, trays, and corners for storing or transporting other goods and materials. It can also be suitably used in a distribution process in which articles are sequentially inserted into a pallet (with or without partition plates).

[Brief explanation of the drawing]

FIG. 1 is a partial longitudinal sectional side view showing a schematic configuration of the hand of an industrial robot according to the present invention, and FIG.
FIG. 3 is an explanatory diagram showing the operating state of the hand over time according to the present invention. 28...first linear actuator, 30...
Hand, 50... Guide member, 60... Second linear actuator.

Claims (1)

[Claims] 1. A wrist 1 provided at the tip of an arm of an industrial robot.
2, a first linear actuator 28 having a first movable member 36 that can extend and retreat in the axial direction of the wrist 12; a workpiece holding hand 30 that detachably holds the first movable member 3 disposed on the wrist 12;
a second linear actuator 60 having a second movable member 62 that can extend and retreat coaxially with the workpiece holding hand 60;
A plurality of guide members 50 are pivotally supported on the second movable member 62 so as to be able to converge and expand with respect to the axis of the wrist 12, and a plurality of guide members 50 are formed to extend in the axial direction on the outer surface of the first movable member 36. and the second linear actuator 6
a guide portion 46 that cooperates with the plurality of guide members 50 to deflect the guide members 50 slightly inwardly in a convergent manner when the second movable member 62 is extended under the biasing action of 0; An industrial robot hand characterized by being composed of. 2. The industrial robot hand according to claim 1, wherein a pneumatic cylinder is used as the first linear actuator 28, and the first movable member 36 is a piston rod of the cylinder 28. 3. The industrial robot hand according to claim 1, wherein a pneumatic cylinder is used as the second linear actuator 60, and the second movable member 62 is a piston rod of the cylinder 60. 4 The guide portion 46 is a plurality of long grooves recessed in the outer surface of the first movable member 36 so as to extend in the axial direction, and the long grooves are tapered so that the depth of the groove gradually increases toward the open end. 48. The industrial robot hand according to any one of claims 1 to 3, wherein 48 is formed. 5 The plurality of guide members 50 are rotatable rollers 5 that are attached to the corresponding guide portions 46.
2, and an elastic member 84 is interposed between each guide member 50 and the wrist 12 to urge the guide member 50 in a direction to converge inward. The hand of the industrial robot described.