JP2000218587A - Universal wrist for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high responsiveness and durability while a structure is simplified, further with generation difficult of operating failure. SOLUTION: This universal wrist is provided between a hand part 6 having a sucker member 8 holding a workpiece and an arm part 4 capable of moving the hand part 6 to an arbitrary position. The wrist has a spherical receiving member 15 fixedly provided in the arm part 4 to be formed with a receiving space 16 in the inside, spherical member 17 turnably provided in the receiving space 16, spherical member 17 and a hand mounting shaft 11, hand mounting seat 12 provided to protrude to the outside of the spherical receiving member 15 from the spherical member 17 to be fixedly provided in the hand part 6, and a piezoelectric element member 18 provided in the spherical receiving member 15 to be made extendable by applying drive voltage so as to press the spherical member 17 to a first spherical seat 13a of the receiving space 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a universal wrist of a robot for absorbing a displacement of a hand portion with respect to a transferred object.

[0002]

2. Description of the Related Art A robot for transporting a transported object to an arbitrary position usually has a hand unit for holding the transported object and an arm unit for moving the hand unit to an arbitrary position.
By operating the hand unit and the arm unit in a constant processing operation according to an operation command from the control device, the transport process from the transport start position to the transport end position is repeatedly performed. At this time, if the transported object has a deformation, a dimensional error, a positioning error at the transport start position, or the like, even if the hand unit reaches the transport start position by a certain processing operation, the hand unit with respect to the transported object does not move. Due to the displacement, a case occurs in which the transferred object cannot be held by the hand unit.

In recent years, attention has been paid to a method of providing a free wrist between a hand portion and an arm portion and absorbing a positional shift by the free wrist. That is, as shown in FIG. 7, for example, a conventional universal wrist includes a spherical member 51 connected to a hand unit 50 and a spherical seat 51 which rotatably accommodates the spherical member 51 and abuts the spherical member 51 in a planar manner. And a spherical receiving member 52 having a spherical seat 52a.
Pusher bolt 53 and pusher bolt 5
A piston gear 54, a screw jack 55, a rack 56, and a reciprocating moving mechanism 57 such as a cylinder device which is a driving source (not shown) for moving the reciprocating member 3 in the pressing direction of the spherical seat 52a.
And According to this configuration, when the transported object is held by the hand unit 50, the forward / backward moving mechanism 5
7, the pressing of the spherical member 51 against the spherical seat 52a by the spherical member 51 is released, and the displacement of the hand unit 50 with respect to the object to be transported is absorbed by the rotation of the spherical member 51. To the hand part 50
Can be held by the hand unit 50 reliably.

[0004]

However, in the above-mentioned conventional structure, the forward / backward moving mechanism 57 for switching between pressing and releasing the spherical member 51 with respect to the spherical seat 52a has many components such as the piston gear 54, the screw jack 55, and the rack 56. However, there is a problem that component costs and assembling costs increase due to the complex combination of the above. Further, since the cylinder device is operated by supplying and discharging the working fluid to press and release the spherical member 51 via the screw jack 55, there is also a problem that the operation speed of pressing and releasing is slow. Further, since the reciprocating movement mechanism 57 meshes each component such as the screw jack 55 and transmits the driving force of the cylinder device to the spherical member 51, fatigue fracture due to shear force applied to each component at the time of transmission easily occurs, and There is also a problem that malfunction is likely to occur due to metal powder due to wear.

Accordingly, the present invention is to provide a free wrist of a robot having a simple structure, high responsiveness and durability, and hardly causing a malfunction.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is provided between a hand unit for holding a transferred object and an arm unit which can move the hand unit to an arbitrary position. A wrist of a robot, wherein the spherical member is fixed to the arm portion and has a housing space formed therein, a spherical member rotatably provided in the housing space, and the spherical member A mounting member protruding out of the spherical receiving member and fixed to the hand portion; and a deformation provided by applying a driving voltage so as to press the spherical member against the wall surface of the housing space provided on the spherical receiving member. And a possible piezoelectric element member.

According to the above arrangement, by deforming the piezoelectric element member and pressing the spherical member against the wall surface of the housing space, the hand portion fixed to the spherical member via the mounting member and the housing space are provided. The arm portion fixed to the spherical receiving member can be fixed. On the other hand, when the deformation of the piezoelectric element member is released, the pressing of the spherical member against the wall surface of the housing space is released, so that the hand portion and the arm portion can be freely rotated. Since the switching between the fixing and the releasing of the fixing of the hand portion and the arm portion is performed only by deforming the piezoelectric element member, the switching is performed in a complicated combination of a plurality of members as in the related art. It has a simple structure, high responsiveness and durability, and is less likely to malfunction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The free wrist according to the present embodiment is provided on a transfer robot 1 having a plurality of degrees of freedom, as shown in FIG. Transfer robot 1
Is an arm unit 4 having a first link 2 and a second link 3 rotatably connected thereto, and a hand unit 6 rotatably provided via a free wrist 5 on a free end side of the arm unit 4. And The hand unit 6 has a suction member 8 having an open front end surface.
When the opening is closed by being brought into contact with the (transported object), the work 7 is sucked and held by reducing the pressure in the opening.

The free wrist 5 provided between the hand unit 6 and the arm unit 4 is provided on the spherical receiving member 15 provided on the end effector mounting seat 9 of the second link 3 and on the spherical receiving member 15. It has a hand mounting seat 12 which is rotatably provided via a mounting shaft 11 and to which the above-described suction member 8 is mounted. As shown in FIG. 1, the spherical receiving member 15 has a second divided member 14 having a rear end surface fixed to the end effector mounting seat 9 and a second divided member 14 fastened to a distal end surface of the second divided member 14 by a bolt (not shown). It is composed of one divided member 13.

The first divided member 13 is a hemispherical first spherical seat 1 formed on the other end face side of the second divided member 14.
3a, and a through hole 13b communicating from the first spherical seat 13a to the center of the distal end face on the hand mounting seat 12 side. On the other hand, the second split member 14 includes a hemispherical second spherical seat 14a formed on the distal end surface side and a second spherical seat 14a.
And a drawer hole 14c which is bifurcated laterally from the draw hole 14b and communicates with the other end surface. And both divided members 1
The first and third spherical seats 13a and 14a form a housing space 16 having a spherical wall surface when the three and fourteen are fastened to form the spherical receiving member 15.

A spherical member 17 having a size smaller than that of the accommodation space 16 is rotatably provided in the accommodation space 16. The above-described hand mounting shaft 11 is fixedly provided at the tip of the spherical member 17. The above-mentioned hand mounting seat 12 is connected to a tip of the hand mounting shaft 11 which is inserted through the through hole 13b and protrudes. A rod-shaped piezoelectric element member 18 is provided in the accommodation hole 14b on the rear end side of the spherical member 17 so as to extend in the axial direction by application of a driving voltage. Note that, as the piezoelectric element member 18, a laminate of piezoelectric elements such as barium titanate can be used, and specifically, an ASB series manufactured by TOKIN Corporation can be used.

The piezoelectric element member 18 includes a lead wire 1
9 is connected, and the lead wire 19 is connected to the lead hole 14c.
Is connected to a DC power supply 20 provided outside of the transfer robot 1 via the. And the piezoelectric element member 18
The axial direction is set so as to be directed to the center point of the spherical member 17, and the relationship between the axial direction length of the piezoelectric element member 18 and the length of the accommodation hole 14b is determined when the piezoelectric element member 18 is extended (the drive voltage Only when the spherical member 17 is pressed against the first spherical seat 13a.

A method of manufacturing the free wrist 5 and the operation of the wrist 5 in the above configuration will be described. First, when manufacturing the free wrist 5, the first divided member 13 and the second divided member 14 are cut out in a block shape, and the first spherical member 13a and the through hole 13b are formed on the first divided member 13 by cutting. At the same time, a bolt screw hole (not shown) is formed. The second spherical member 14 a
, The receiving hole 14b and the extraction hole 14c are formed by cutting, and a bolt screw hole (not shown) is formed. Thereafter, the piezoelectric element member 18 is inserted into the receiving hole 1 of the second divided member 14.
4b, and the lead wire 19 connected to the piezoelectric element member 18 is drawn out through the drawing hole 14c.

Next, the hand-mounted shaft 1 is attached to the spherical member 17.
After the rear end of the first spherical seat 14 is
While holding at a, the first divided member 13 is brought into contact with the second divided member 14 so as to cover the first divided member 13 from above the spherical member 17. Then, the first divided member 13 and the second divided member 14 are fastened by screwing a bolt into the bolt screw hole to form a spherical receiving member 15, and a spherical space is formed in the accommodation space 16 in the spherical receiving member 15. The member 17 is rotatably housed. Thereafter, the hand mounting seat 1 is attached to the tip of the hand mounting shaft 11.
By attaching 2, the fabrication of the free wrist 5 by processing and assembly is completed. Then, as shown in FIG. 2, the second split member 14 of the free wrist 5 is fixed to the end effector attachment seat 9 and the suction member 8 is attached to the hand attachment seat 12, thereby connecting the free wrist 5 to the second link. After assembling between the handpiece 3 and the hand unit 6, the lead wire 19 is connected to an external DC power supply 20.

Next, when a transfer command of the work 7 is input to the transfer robot 1 to which the free wrist 5 is assembled as described above, first, the drive voltage from the DC power supply 20 is applied to the piezoelectric element. The application to the member 18 causes the piezoelectric element member 18 to elongate. When the piezoelectric element member 18 extends, the rear end of the piezoelectric element member 18
, The tip moves in the direction of the arrow. Then, the movement of the distal end portion moves the spherical member 17 to the first position.
The spherical member 1 is pressed against the first spherical seat 13a of the divided member 13.
7 and the first spherical seat 13a are brought into planar contact. As a result, the suction member 8 provided on the spherical member 17 via the hand mounting shaft 11 and the hand mounting seat 12 allows the free wrist 5
, For example, when moving from the standby position to the transport start position,
2 does not swing.

Thereafter, when the suction member 8 reaches the transport start position and is positioned so that the tip end surface of the suction member 8 is in contact with the side surface of the work 7 based on the teaching data registered in advance, FIG. As shown in FIG. 1, by stopping the application of the driving voltage to the piezoelectric element member 18, the piezoelectric element member 18 is reduced, and the first spherical seat 13 of the spherical member 17 is reduced.
Release the pressure on a. Accordingly, the spherical member 17 is rotatably accommodated in the accommodation space 16,
The suction member 8 provided on the spherical member 17 via the hand mounting shaft 11 and the hand mounting seat 12 is in a rotatable state.

Next, as shown in FIG.
Move in the direction. At this time, when the work 7 is inclined as shown by a two-dot chain line in the drawing, a part of the tip end surface of the suction member 8 comes into contact with the work 7 so that a part of the suction member 8 is deflected in the B direction. A force is applied, and a turning force in the C direction acts on the suction member 8 by a moment due to the reaction force in the B direction. Therefore, the rotatable adsorbing member 8 rotates as shown by a two-dot chain line in FIG. Thereafter, as shown in FIG. 1, by applying a drive voltage to the piezoelectric element member 18, the suction member 8 is moved to the free wrist 5 as described above.
To a fixed state. Then, the work 7 is sucked by the suction member 8 by reducing the pressure inside the suction member 8, and then the work 7 is transferred from the transport start position to the transport end position.

As described above, the adjustable wrist 5 of the present embodiment
Is a freely movable transfer robot 1 provided between a hand unit 6 having a suction member 8 for holding a work 7 (object to be transferred) and an arm unit 4 capable of moving the hand unit 6 to an arbitrary position. A wrist, a spherical receiving member 15 fixed to the arm portion 4 and having a housing space 16 formed therein; a spherical member 17 rotatably provided in the housing space 16; A mounting member having a spherical member 17, a hand mounting shaft 11, and a hand mounting seat 12, protruding from the member 15 and fixed to the hand section 6;
5 and a piezoelectric element member 18 that can be expanded by applying a drive voltage so as to press the spherical member 17 against the first spherical seat 13 a (wall surface) of the housing space 16.

According to the above configuration, the piezoelectric element member 18 is extended to place the spherical member 17 in the first spherical seat 1 of the accommodation space 16.
3a, the hand 6 fixed to the spherical member 17 via the mounting member and the arm 4 fixed to the spherical receiving member 15 having the accommodation space 16 are fixed. be able to. On the other hand, the piezoelectric element member 1
8 is released, the first spherical seat 13 of the accommodation space 16 is released.
Since the pressing of the spherical member 17 against a is released, the hand unit 6 and the arm unit 4 can be made rotatable. Since the switching between the fixing of the hand unit 6 and the fixing of the arm unit 4 and the release of the fixing are performed only by extending the piezoelectric element member 18, the switching is performed by combining a plurality of members in a complicated manner as in the related art. Compared to the case, it is possible to have a simple structure, high responsiveness and durability, and furthermore, it is difficult to cause malfunction.

In the present embodiment, the suction member 8 for sucking the work 7 is exemplified as the hand unit 6,
However, the present invention is not limited to this. For example, the hand unit 6 may hold the work 7 with a pair of openable and closable fingers.

Furthermore, in the present embodiment, the spherical member 17 is configured to be pressed by one piezoelectric element member 18, but the present invention is not limited to this. That is, as shown in FIG. 3, a plurality of receiving holes 14b and drawing-out holes 14c are formed in the spherical receiving member 15, and each receiving hole 14b is formed.
The piezoelectric element members 18 are arranged on the spherical receiving member 15 in a direction in which the plurality of piezoelectric element members 18 are deformed (elongation direction, etc.).
The spherical member 17 may be pressed by the plurality of piezoelectric element members 18 against the first spherical seat 13a by setting the rear end side toward the center point of the spherical member 17. In this case, the plurality of piezoelectric element members 18
Since the spherical member 17 can be pressed with a large pressing force, the fixed state (restricted state) between the hand section 6 and the arm section 4 can be strengthened.

Further, in the present embodiment, the piezoelectric element member 18 is configured to directly press the spherical member 17 against the first spherical seat 13a. However, the present invention is not limited to this. The configuration shown in FIG.

That is, the free wrist 5 has a first divided member 23 and a second divided member 24. A first spherical member 23a and a through hole 23b having a hemispherical shape are formed in the first divided member 23, and a plurality of spring insertion holes 23c communicating from the front end surface to the rear end surface are formed around the first spherical seat 13. Is formed. On the other hand, the second divided member 24 has the second
A spherical seat 24a is formed, and a spring insertion hole 24c is formed at a position corresponding to the above-described spring insertion hole 23c. Further, a receiving hole 24b is formed on the distal end surface side of the second divided member 24. The receiving hole 24b is opened at the distal end surface of the receiving hole 24b, and the second spherical seat 2 is formed.
It is arranged so as not to overlap with the spring insertion hole 24c around 4a.

A spring member 25 is provided in each of the spring insertion holes 23c and 24c, and the spring member 25 is arranged so that the first divided member 23 and the second divided member 24 come into contact with each other.
It is pulled by support members 27 provided at both ends of the spring insertion holes 23c and 24c. In addition, the first divided member 23 and the second divided member 24
A piezoelectric element member 18 is provided so as to release the contact state with the piezoelectric element member 18. The piezoelectric element member 18 is connected to a DC power supply 20 via a lead wire 19. The accommodation space 26 having the first spherical seat 23a and the second spherical seat 24a as wall surfaces is formed inside the first divided member 23 and the second divided member 24 configured as described above. Accommodation space 2
6 is provided with the above-mentioned spherical member 17 rotatably, and the spherical member 17 is provided with a hand mounting seat 12 via a hand mounting shaft 11.

In the above configuration, when the piezoelectric element member 18 is not expanded, the spring member 25 urges the contracting force so that the first divided member 23 and the second divided member 24 come into contact with each other. As a result, the spherical member 17 is separated from the first divided member 23.
Further, the spherical member 17 is firmly fixed by being pressed by the two spherical seats 23a and 24a of the second divided member 24 with a large contact area. On the other hand, when the piezoelectric element member 18 is extended, the first split member 23 and the second
Since the divided member 24 is separated from the divided member 24, the spherical member 17 is rotatable in the accommodation space 26.

In the present embodiment, the spherical member 17 is pressed against the first spherical seat 13a serving as the wall surface of the housing space 16 by extending the piezoelectric element member 18. However, the present invention is not limited to this. Instead, if the spherical member 17 can be pressed against the first spherical seat 13a, any deformation of the piezoelectric element member 18 can be used. That is,
The spherical member 17 can also be pressed against the first spherical seat 13a by contracting or bending the piezoelectric element member 18 in a direction perpendicular to the axis.

Specifically, as shown in FIG. 5, the drive power supply is normally turned on to extend the power supply, and when used, the drive power supply is switched off to accommodate the apparently contracted piezoelectric element member 18 '. It is provided in the hole 24b. Then, both ends of the piezoelectric element member 18 'are respectively joined to the divided members 23 and 24, and a spring member 25 is provided so as to separate the divided members 23 and 24, whereby the piezoelectric element member 18'
May be configured so that the divided members 23 and 24 are attracted to each other by the contraction of.

As shown in FIG. 6, for example, two types of piezoelectric element members having different elongation rates are joined in parallel, or a piezoelectric element member is joined to the side surface of a non-elongated metal piece to bend around the center. Element 1 having a structure to be
8 "may be provided in the accommodation hole 14b so that the spherical member 17 is pressed at the top of the side surface when the piezoelectric element member 18" is bent.

[0029]

According to the present invention, there is provided a universal wrist of a robot provided between a hand for holding a transferred object and an arm capable of moving the hand to an arbitrary position. A spherical receiving member having a housing space formed therein, a spherical member rotatably provided in the housing space, and a hand protruding from the spherical member to the outside of the spherical receiving member; And a piezoelectric element member provided on the spherical receiving member and deformable by applying a driving voltage so as to press the spherical member against a wall surface of the housing space. .

According to the above configuration, by deforming the piezoelectric element member and pressing the spherical member against the wall surface of the housing space, the hand portion fixed to the spherical member via the mounting member and the housing space are provided. The arm portion fixed to the spherical receiving member can be fixed. On the other hand, when the deformation of the piezoelectric element member is released, the pressing of the spherical member against the wall surface of the housing space is released, so that the hand portion and the arm portion can be freely rotated. Since the switching between the fixing and the release of the fixing of the hand portion and the arm portion is performed only by deforming the piezoelectric element member, the switching is performed more complicatedly than in the conventional case in which a plurality of members are combined and switched. It has a simple structure, high responsiveness and high durability, and further has the effect of making it difficult for malfunctions to occur.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a free wrist of a robot according to the present invention.

FIG. 2 is an explanatory diagram showing a state in which a free wrist is attached to a robot.

FIG. 3 is a schematic configuration diagram of a free wrist of the robot of the present invention.

FIG. 4 is a schematic configuration diagram of a free wrist of the robot of the present invention.

FIG. 5 is a schematic configuration diagram of a free wrist of the robot of the present invention.

FIG. 6 is a schematic configuration diagram of a free wrist of the robot of the present invention.

FIG. 7 is a schematic configuration diagram of a free wrist of a conventional robot.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveying robot 2 1st link 3 2nd link 4 Arm part 5 Free wrist 6 Hand part 7 Work 8 Suction member 9 End effector attachment seat 10 Wrist body 11 Hand attachment shaft 12 Hand attachment seat 13 1st division member 13a 1st Spherical seat 14 Second divided member 14a Second spherical seat 15 Spherical receiving member 16 Housing space 17 Spherical member 18 Piezoelectric element member 19 Lead wire 20 DC power supply 23 First divided member 23a First spherical seat 24 Second divided member 24a Second Spherical seat 25 Spring member 26 Housing space 27 Support member

Claims (1)

[Claims] 1. A free wrist of a robot provided between a hand portion for holding a transferred object and an arm portion capable of moving the hand portion to an arbitrary position, wherein the wrist is fixed to the arm portion. A spherical receiving member having an accommodation space formed therein, a spherical member rotatably provided in the accommodation space, and a protrusion protruding from the spherical member to the outside of the spherical reception member;
An attachment member fixed to the hand portion; and a piezoelectric element member provided on the spherical receiving member and deformable by application of a driving voltage so as to press the spherical member against a wall surface of the housing space. The universal wrist of a robot.