JPH106269A - Industrial robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrial robot whose arm and wrist are constructed light by introducing such a configuration that the torque of the drive part is transmitted to the axes of the wrist through a transmitting member which has a spiral detention part. SOLUTION: The second arm 6 is fitted at the tail with motors 13-15 which are to drive each axis of a robot wrist 7. The output shafts of the motors 13-15 are coupled with rods 22-24 extending along the second arm 6, and the ends of these rods 22-24 are coupled with other rods 25-27. The rods 25 and 27 are furnished at the ends with worms 37 and 38 which serve as a detention part in a spiral form, and worm wheels 47 and 48 to mesh with them are installed in the first case 10. The torque of the motors 13 and 15 is transmitted to the axes of the wrist 7 through the worms 37 and 38 and wheels 47 and 48. The rods 22-24 are inserted into the second arm 6 and the worms 37 and 38 and wheels 47 and 48 are accommodated in the first case 10 so that a lightweight construction is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial robot and, more particularly, to an improvement in a transmission mechanism for transmitting a driving force to each axis of a wrist attached to a tip of an arm.

[0002]

2. Description of the Related Art Generally, a playback type articulated robot is used as an industrial robot installed in an automation line of a factory or the like. This type of industrial robot
Generally, a base, a turning base that turns on the base, a first arm that stands on the turning base, a second arm that extends horizontally from an upper end of the first arm, and a tip of the second arm Consists of an attached wrist.

[0003] A jig such as a paint gun or a hand is attached to the tip of the wrist, and the arm and the wrist operate so as to perform a predetermined operation in conjunction with the transfer of the work. The wrist has three X-axis directions, a Y-axis direction,
The rotational force in the Z-axis direction is transmitted and driven to perform a three-dimensional operation.

A motor for driving each axis of the wrist is attached to the rear of the second arm, and the rotational driving force of the motor is transmitted via a transmission mechanism disposed inside the second arm. It is transmitted to each axis of the wrist. As described above, as a transmission mechanism for transmitting the rotational driving force of the motor to the wrist,
For example, a rod for driving one axis is inserted through the center of the second arm, and a double torque tube for driving the other two axes is provided outside the rod.

Therefore, the first rotating shaft composed of one rod and the second and third rotating shafts composed of two torque tubes are inserted concentrically inside the second arm. The shafts are rotatably held by bearings so that the shafts do not interfere with each other. The end of each shaft is configured to transmit rotational driving force to each shaft of the wrist via a bevel gear.

In another transmission mechanism, three rods are arranged in parallel inside a second arm, a first rotating shaft composed of one rod and two torques inside a wrist. The second and third rotating shafts formed of tubes are inserted concentrically, and further provided with a rotating shaft and two torque tubes extending in a direction perpendicular to these shafts. The rotational driving force of the three rods inserted through the shaft is transmitted to each shaft of the wrist and the torque tube via bevel gears.

[0007]

In the conventional structure using the above-described transmission mechanism, one arm is provided inside the second arm.
There are provided two rods, two torque tubes, and a bearing for bearing each shaft. In particular, since the two torque tubes are made of iron and have a ring-shaped cross section compared to the rod, the cross-sectional area is And the weight is increased accordingly. Therefore, the total weight of the second arm becomes considerably heavy, and it is necessary to increase the size of the motor that drives the second arm to secure the driving torque.

In the conventional configuration using the transmission mechanism as described above, the three rods are arranged in parallel inside the second arm, so that the total weight of the second arm is reduced. On the other hand, the weight of the wrist is increased because the two torque tubes are attached to the wrist.

Therefore, the weight of the distal end of the second arm supporting the wrist increases, and the rigidity of the second arm must be increased by increasing the thickness of the second arm. As a result, the weight of the second arm itself also increases, which not only limits the weight of a jig (eg, a paint gun, a hand, etc.) attached to the tip of the wrist,
Since the operating speed of the robot is reduced, it is necessary to increase the size of the motor that drives the second arm.

Accordingly, an object of the present invention is to provide an industrial robot which has solved the above-mentioned problems.

[0011]

In order to solve the above problems, the present invention has the following features. The present invention relates to an industrial robot having a driving unit for driving a wrist, and a transmission mechanism for transmitting a rotational driving force of the driving unit to each axis of the wrist, wherein the transmission mechanism has a spiral engagement. The rotational driving force of the drive unit is transmitted to each shaft of the wrist via a transmission member having a part.

Therefore, according to the present invention, the wrist can be driven via a transmission member having a helical engagement portion such as a worm gear instead of the torque tube, so that the torque tube used in the conventional transmission mechanism can be used. The transmission mechanism can be made unnecessary and the weight of the transmission mechanism can be reduced, and accordingly, the size of the arm driving motor can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment of an industrial robot according to the present invention. The industrial robot 1 is installed in the coating area 2 and when an object to be coated is transported,
This is a playback type articulated robot that performs a painting operation that has been taught in advance. The industrial robot 1 is generally
A base 3 and a turning base 4 that turns on the base 3 around the A axis.
A first arm 5 standing on the revolving base 4 and swinging about the B axis; and a C extending from the upper end of the first arm 5 in the horizontal direction.
It comprises a second arm 6 that swings around an axis and a wrist 7 provided at the tip of the second arm 6.

A coating gun 9 is attached to the tip of the wrist 7 via a bracket 8. The painting gun 9 is the first
The arm 5 and the second arm 6 swing to move to a predetermined painting height position, and the wrist 7 changes the paint spraying direction. The wrist 7 is provided with a first wrist 7 fixed to the tip of the second arm 6.
A case 10, a second case 11 that rotates around the D axis,
The third case 12 rotating around the E axis and the coating gun 9 are
It comprises a shaft 13 that rotates around the axis. Case 11, 1
The shaft 2 and the shaft 13 are individually driven by motors 14 to 16 attached to the base end of the second arm 6. And
The rotational driving force of each of the motors 14 to 16 is transmitted to the cases 11 and 12 and the shaft 13 of the wrist 7 via a transmission mechanism (hidden and invisible in FIG. 1) provided inside the second arm 6 and the wrist 7. Is transmitted to

In the industrial robot 1, each movable part is driven by a motor (not shown) to adjust the position and the painting direction of the painting gun 9, and each motor is controlled by a control signal from a robot controller 17. Is controlled by An encoder (not shown) for detecting the angle of each movable part is incorporated in each joint of the industrial robot 1, and a detection signal output from the encoder is fed back to the robot controller 17. By controlling each motor, the turning base 4, the first arm 5,
The second arm 6 and the wrist 7 are accurately driven.

A color change valve unit 18 is mounted on the second arm 6. The coating gun 9 is connected to a color changing valve unit 18 via a coating supply tube 19. In addition, the color changing valve unit 18 includes:
A plurality of paint supply tubes 20 are connected, and paint of each color is supplied through each paint supply tube 20. Each valve of the color change valve unit 18 is switched and controlled by a color change control device (not shown) provided in the robot controller 17 to selectively supply the specified paint to the coating gun 9.

Here, the structure of the transmission mechanism provided inside the second arm 6 and the wrist 7 will be described. FIG. 2 is a longitudinal sectional view showing the internal structure of the second arm 6 and the wrist 7. The second arm 6 is formed in a hollow shape, and motors 13 to 15 for driving the respective axes of the wrist 7 are attached to the rear end. Also, each of the motors 13 to 15 is
The arm 6 is protected by a cover 21 attached to the rear end.

The output shafts of the motors 13 to 15 are connected to rods 22 to 24 extending along the second arm 6. The rods 22 to 24 extend in parallel and are held so as not to interfere with each other. As described above, since the inside of the second arm 6 has the configuration in which the three rods 22 to 24 extend in parallel, the weight can be significantly reduced as compared with the case where the torque tube is concentrically mounted. Since it is possible and the rigidity of the second arm 6 can be reduced, the thickness of the second arm 6 can be reduced to reduce the weight of the second arm 6 itself.

The motor 13 constitutes a first drive unit for driving the case 11 around the D axis, and the motor 14
Constitute a second drive unit for driving the motor 15 around the E axis, and the motor 15
Constitutes a third drive unit for driving the shaft 13 around the F axis.
Further, at the front end of the second arm 6, bearing units 28 to 30 that support the rods 25 to 27 are held. One end of each of the rods 25 to 27 is connected to the rods 22 to 24, and transmits the rotational driving force of each of the motors 13 to 15.

Each of the bearing units 28 to 30 has a pair of bearings 31 and 32, of which the bearing units 28 and
Reference numeral 30 has a spacer 33 interposed between bearings 31 and 32 and is supported by brackets 34 and 35. In the bearing unit 29, a pair of bearings 31 and 32 are held by an annular pressing plate 36.

FIG. 3 is a longitudinal sectional view of the inside of the first case 10 viewed from the axial direction of the second arm. The rod 25, 2
7 has a worm 37 as a spiral engaging portion,
38 are provided. Further, rods 25 to 27 protrude inside the first case 10. The driving pulley 40 is attached to the end of the rod 26.

Reference numeral 41 denotes a rod arranged in parallel with the rod 26, and is supported by a bearing unit 42. Note that the bearing unit 42 is held by a bracket 43 fixed inside the first case 10. A driven pulley 44 is attached to one end of the rod 41, and a bevel gear 45 is attached to the other end.
Is attached. A timing belt 46 is wound around the outer periphery of the driving pulley 40 and the driven pulley 44.

Therefore, the rotational driving force of the motor 14 is controlled by the rods 23 and 26, the driving pulley 40, the timing belt 4
6, transmitted to the driven pulley 44 and the rod 41. Worm wheels 47 and 48 meshing with the worms 37 and 38 are provided inside the first case 10. The worm wheels 47 and 48 are
Hollow shaft 4 extending in a direction orthogonal to the direction in which 8 extends
It is provided at the ends of 9, 50. Worms 37, 38
Extends in the tangential direction of the worm wheels 47 and 48, and the teeth formed helically on the outer circumference of the worms 37 and 38 mesh with the teeth formed helically on the outer circumference of the worm wheels 47 and 48. ing.

The rod 5 is inserted into the through hole of the inner shaft 50.
1 is inserted. The rod 51 is supported by bearings 52 provided at both ends of the through hole of the shaft 50. One end of the rod 51 has a bevel gear 4 of the rod 41
A bevel gear 53 with which the gear 5 meshes is attached, and a bevel gear 54 is attached to the other end of the rod 51.

The shaft 50 is supported by bearings 55 provided at both ends of a through hole of the shaft 49. Axis 5
A worm wheel 48 is attached to one end of the shaft 0, and a bevel gear 56 is attached to the other end of the shaft 50. The shaft 49 is supported by a bearing 57 provided on the bottom of the first case 10 and is fixed to the upper surface of the second case 11. Therefore, the second case 11 is
It is provided so that it may rotate integrally with.

Further, a shaft 59 having a bevel gear 58 meshing with the bevel gear 54 and a hollow shaft 61 having a bevel gear 60 meshing with the bevel gear 56 are provided inside the second case 11. I have. The shaft 59 and the shaft 61 are disposed coaxially and are supported by bearings 62 and 63, respectively.
The end of the shaft 61 is connected to the side surface of the third case 12. Therefore, the third case 12 rotates integrally with the shaft 61.

The shaft 59 is provided inside the third case 12.
A shaft 66 having a bevel gear 65 meshing with a bevel gear 64 provided at the other end of the third case 12 is provided, and a speed reducer 67 for reducing the rotation of the shaft 66 is provided on the lower surface of the third case 12. The speed reducer 67 has a shaft 13 as an output shaft, and rotates the coating gun 9 around the F axis via the shaft 13.

Thus, inside the first case 10,
The rotation of the rods 22 and 24 causes the second case 11 and the third case 11 to rotate through the worms 37 and 38 and the worm wheels 47 and 48.
Since the configuration is such that the torque is transmitted to the case 12, the weight can be reduced as compared with the conventional configuration in which the torque tubes are concentrically arranged. Therefore, the rigidity of the second arm 6 can be reduced and the weight of the second arm 6 itself can be reduced. As a result, the capacity of the motor that drives the second arm 6 can be reduced, and the The size can be reduced.

Further, the worm 3 having spiral teeth
Since the worm wheels 7 and 38 are always engaged with the worm wheels 47 and 48, the worm wheels 47 and 48 do not rotate freely even if the power of the motors 13 and 15 is turned off. It is not necessary to provide a brake mechanism in the vehicle.

The shaft 4 provided in the first case 10
Although 9, 50 are formed in a hollow shape, they cannot be rods due to their configuration. Here, the operation of the transmission mechanism configured as described above will be described. The rotational driving force of the motor 13 is transmitted to the second case 11 via the rods 22 and 25, the worm 37, the worm wheel 47, and the shaft 49 that constitute the first transmission mechanism. Thus, the second case 11
It is driven by the motor 13 to rotate around the D axis.

The rotational driving force of the motor 14 is controlled by the rods 23 and 26 and the driving pulley 4 constituting the second transmission mechanism.
0, a timing belt 46, a driven pulley 44, a rod 41, bevel gears 45 and 53, a shaft 51, bevel gears 54 and 58,
Shaft 59, bevel gears 64 and 65, shaft 66, reducer 67, shaft 1
It is transmitted to the coating gun 9 via 3. Thus, the shaft 13
Is rotated about the F axis by the motor 14.

The rotational driving force of the motor 15 is controlled by the rods 24 and 27, the worm 38, the worm wheel 48, the shaft 50, the bevel gears 56 and 60, and the shaft 6 constituting the third transmission mechanism.
1 to the third case 12. Thus, the third case 12 is driven by the motor 15 to rotate around the E axis.

FIGS. 4 and 5 show a second embodiment of the present invention.
The second embodiment differs from the first embodiment in that the worms 37 and 38 are replaced with screws 37A and 38A.
And worm wheels 47 and 48 are replaced with screw gears 47A and 48A. Therefore,
The screws 37A and 38A extend in the tangential direction of the screw gears 47A and 48A, and the helical threads formed on the outer circumference of the screws 37A and 38A are formed helically on the outer circumference of the screw gears 47A and 48A. It is in mesh with your teeth.

Therefore, the rotational driving force of the motor 13 is
The power is transmitted to the second case 11 via the rods 22 and 25, the screw 37A, the screw gear 47A, and the shaft 49 that constitute the transmission mechanism. As described above, the second case 11 is driven through the screw 37A and the screw gear 47A to rotate around the D axis.

The rotational driving force of the motor 15 is supplied to the third case 12 via the rods 24 and 27, the screw 38A, the screw gear 48A, the shaft 50, the bevel gears 56 and 60, and the shaft 61 constituting the third transmission mechanism. Is transmitted to Thus, the third case 12 is driven around the E axis by being driven via the screw 38A and the screw gear 48A.

As described above, in the configuration of the second embodiment, the rotation of the rods 22 and 24 is transmitted to the second case 11 and the third case 12 via the worms 37 and 38 and the worm wheels 47 and 48. Therefore, the weight can be reduced as compared with the conventional configuration in which the torque tubes are arranged concentrically. Therefore, the rigidity of the second arm 6 can be reduced and the weight of the second arm 6 itself can be reduced. As a result, the capacity of the motor that drives the second arm 6 can be reduced, and the The size can be reduced.

Further, a screw 37 having a helical thread is provided.
Since the gears A and 38A are always meshed with the screw gears 47A and 48A, even if the power of the motors 13 and 15 is turned off, the screw gears 47A and 48A do not rotate without permission. It is not necessary to provide a brake mechanism in the vehicle.

FIGS. 6 and 7 show a third embodiment of the present invention.
The third embodiment is different from the first embodiment in that a worm and a worm wheel are used instead of the driving pulley 40, the timing belt 46, the driven pulley 44, the rod 41, and the bevel gears 45 and 53. It is in the point which did.

The rods 22 to 24 connected to the output shafts of the motors 13 to 15 are connected to worms 37 to 39 via rods 25 to 27. Each worm 37-39
Extend in parallel to the worm wheels 68, 47, 4
8 in the tangential direction.

The worm wheels 68, 47, 48
Are provided at ends of shafts 49 to 51 extending in a direction perpendicular to the extending direction of the worms 37 to 39. Axis 49 ~
51 is provided coaxially and has a total length of each worm 37.
The length is set according to the interval of ~ 39. The worms 37 to 39 extend in a tangential direction of the worm wheels 68, 47, 48, and spirally formed teeth on the outer circumference of the worms 37 to 38 have the worm wheels 68, 47, 4.
8 meshes with spirally formed teeth on the outer periphery.

Therefore, inside the first case 10, the rotation of the rods 22 to 24 is transmitted to the second case 11 and the third case 12 via the worms 37 to 39 and the worm wheels 68, 47, 48. Therefore, the weight can be reduced as compared with the conventional configuration in which the torque tubes are arranged concentrically. Therefore, the second arm 6
The rigidity of the second arm 6 itself can be reduced and the weight of the second arm 6 itself can be reduced. As a result, the capacity of the motor that drives the second arm 6 can be reduced, so that the size of the arm driving motor can be reduced. it can.

Further, a worm 37 having spiral teeth
39 are always engaged with the worm wheels 68, 47, 48, so that even if the power of the motors 13 to 15 is turned off, the worm wheels 68, 47, 48 do not rotate freely. It is not necessary to provide a brake mechanism for 13 to 15.

As shown in FIG. 7, the worms 37 and 39 mesh on the left side of the worm wheels 68 and 47, the middle worm 38 meshes on the left side of the worm wheel 48, and the worms 37 to 39 interfere with each other. It is arranged not to be. Here, the operation of the transmission mechanism configured as described above will be described.

The rotational driving force of the motor 13 is the first driving force described above.
As in the embodiment, the rods 22 and 2 constituting the first transmission mechanism
5, the worm 37, the worm wheel 47, and the shaft 49 are transmitted to the second case 11. As described above, the second case 11 is driven by the motor 13 and rotates around the D axis.

The rotational driving force of the motor 14 is controlled by the rods 23 and 26, the worm 38, the worm wheel 48, the shaft 50, the bevel gears 56 and 60, and the shaft 6 constituting the second transmission mechanism.
1 to the third case 12. As described above, the third case 12 is driven by the motor 14 and rotates around the E axis.

The rotational driving force of the motor 15 is controlled by the rods 24 and 27, the worm 39, the worm wheel 68, the shaft 51, the bevel gears 54 and 58, and the shaft 5 constituting the third transmission mechanism.
9, the bevel gears 64 and 65, the shaft 66, the reduction gear 67, and the shaft 13 are transmitted to the coating gun 9. Thus, the shaft 13 is
It is driven by the motor 14 to rotate around the F axis.

In the above-described embodiment, the industrial robot having the configuration in which the coating gun 9 is mounted on the tip of the wrist 7 is described as an example. However, the present invention is not limited to this, and the robot may be mounted on another jig. Of course, it is also applicable.

[0048]

As described above, according to the present invention, the wrist can be driven via a transmission member having a helical engagement portion such as a worm gear instead of the torque tube, and therefore, it can be used in a conventional transmission mechanism. Since the configuration in which the rods are arranged in parallel without the need for the torque tube can be adopted, the weight of the transmission mechanism can be reduced as compared with the configuration using the torque tube. As a result, the rigidity of the arm can be reduced, so that the thickness of the arm itself can be reduced and the weight can be reduced, and the size of the arm driving motor can be reduced accordingly. In addition, when the motor is stopped, the spiral engaging portion is in a non-rotatable state. Therefore, even when the power is turned off, the wrist portion can be prevented from rotating by its own weight, and the motor brake can be eliminated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of an industrial robot according to the present invention.

FIG. 2 is a longitudinal sectional view of a second arm provided with a first embodiment of a transmission mechanism for driving a wrist.

FIG. 3 is a longitudinal sectional view of the inside of the first case shown in FIG. 2 as viewed from an axial direction of a second arm.

FIG. 4 is a longitudinal sectional view of a second arm provided with a second embodiment of a transmission mechanism for driving a wrist.

5 is a longitudinal sectional view of the inside of the first case shown in FIG. 4 as viewed from an axial direction of a second arm.

FIG. 6 is a longitudinal sectional view of a second arm provided with a third embodiment of a transmission mechanism for driving a wrist.

FIG. 7 is a longitudinal sectional view of the inside of the first case shown in FIG. 6 as viewed from an axial direction of a second arm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Industrial robot 3 Base 4 Revolving base 5 1st arm 6 2nd arm 7 Wrist part 9 Painting gun 10 1st case 11 2nd case 12 3rd case 14-15 Motor 22-27 Rod 37-39 Worm 47, 48, 68 Worm wheel 37A, 38A Screw 47A, 48A Screw gear

Claims (1)

[Claims] 1. An industrial robot comprising: a driving unit that drives a wrist; and a transmission mechanism that transmits a rotational driving force of the driving unit to each axis of the wrist, wherein the transmission mechanism has a helical engagement. An industrial robot for transmitting the rotational driving force of the drive unit to each axis of the wrist via a transmission member having a joint.