JP3785681B2 - Industrial robot - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an industrial robot, and more particularly, to an improvement in a transmission mechanism that transmits a driving force to each axis of a wrist attached to the tip of an arm.
[0002]
[Prior art]
In general, playback type articulated robots are mainly used for industrial robots installed in an automated line of a factory or the like. This type of industrial robot generally includes a base, a turning base that turns on the base, a first arm that stands on the turning base, and a second arm that extends horizontally from the upper end of the first arm. And a wrist attached to the tip of the second arm.
[0003]
For example, a jig such as a paint gun or a hand is attached to the tip of the wrist, and the arm and the wrist are operated so as to perform a predetermined operation in accordance with the conveyance of the workpiece. The wrist portion is driven by the rotational force transmitted in the three X-axis directions, the Y-axis direction, and the Z-axis direction orthogonal to each other, and can perform a three-dimensional operation.
[0004]
A motor for driving each axis of the wrist is attached to the rear part of the second arm, and the rotational driving force of the motor is transmitted to the wrist part via a transmission mechanism arranged inside the second arm. It is transmitted to each axis.
In this way, as the transmission mechanism (1) for transmitting the rotational driving force of the motor to the wrist, for example, a rod for driving one shaft is inserted in the center of the second arm, and the other two shafts are connected to the outside of the rod. Two torque tubes for driving are arranged.
[0005]
Accordingly, a first rotating shaft made of one rod and second and third rotating shafts made of two torque tubes are inserted concentrically into the second arm, and each shaft is The shafts are rotatably held by bearings so that they do not interfere with each other. And the edge part of each axis | shaft becomes a structure which transmits rotational driving force to each axis | shaft of a wrist part via a bevel gear.
[0006]
In another transmission mechanism {circle around (2)}, three rods are arranged in parallel in the second arm, the first rotating shaft consisting of one rod inside the wrist, and two torques. A second and third rotating shafts made of tubes are inserted concentrically, and further, a rotating shaft extending in a direction orthogonal to these and two torque tubes are provided, and the inside of the second arm The rotational driving force of the three rods inserted through the shaft is transmitted to each axis of the wrist and the torque tube via the bevel gear.
[0007]
[Problems to be solved by the invention]
In the conventional configuration using the transmission mechanism (1) as described above, one rod, two torque tubes, and a bearing for bearing each shaft are arranged inside the second arm. In particular, since the two torque tubes are made of iron and have a circular cross section compared to the rod, the cross sectional area is large 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 ensure the driving torque.
[0008]
Further, in the conventional configuration using the transmission mechanism (2) as described above, since the three rods are arranged in parallel inside the second arm, the total weight of the second arm is reduced. However, since the two torque tubes are attached to the wrist, the weight of the wrist is increased.
[0009]
Therefore, the weight of the tip portion of the second arm that supports the wrist portion is increased, and accordingly, the thickness of the second arm must be increased to increase the rigidity of the second arm. As a result, the weight of the second arm itself also increases, which not only restricts the weight of a jig (for example, a paint gun, a hand, etc.) attached to the tip of the wrist, but also reduces the operating speed of the robot. Therefore, it is necessary to increase the size of the motor that drives the second arm.
[0010]
Accordingly, an object of the present invention is to provide an industrial robot that solves the above problems.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following features. The present invention includes a wrist portion having three mutually orthogonal axes, and three motors for driving each axis of該手neck, a transmission mechanism for transmitting the rotational driving force of the three motors for each axis of the wrist portion In the industrial robot having the wrist portion at the front end and the arm having the three motors at the rear end,
The transmission mechanisms are respectively connected to the output shafts of the three motors, extend along the arms so as not to interfere with each other, and are supported by bearings near the tips in the arms and supported by the bearings. 3 rods provided on the outer periphery with three rods attached with worms extending further to the tip of the portions, and spiral teeth meshing tangentially with the worms of the three rods. And an industrial robot characterized by comprising two worm wheels.
[0012]
Therefore, according to the present invention, the wrist portion 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 is not required. It is possible to reduce the weight of the transmission mechanism, and accordingly, it is possible to reduce the size of the arm driving motor.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a first embodiment of an industrial robot according to the present invention.
The industrial robot 1 is a playback-type multi-joint robot that is installed in the painting area 2 and performs a painting operation taught in advance when an object to be painted is conveyed. The industrial robot 1 generally includes a base 3, a turning base 4 that turns around the A axis on the base 3, a first arm 5 that stands on the turning base 4 and swings around the B axis, The second arm 6 extends horizontally from the upper end of one arm 5 and swings around the C axis, and a wrist portion 7 provided at the tip of the second arm 6.
[0014]
A coating gun 9 is attached to the tip of the wrist 7 via a bracket 8. The coating gun 9 is moved to a predetermined coating height position by the swing of the first arm 5 and the second arm 6, and the paint spraying direction is changed by the wrist portion 7.
The wrist 7 includes a first case 10 fixed to the tip of the second arm 6, a second case 11 that rotates about the D axis, a third case 12 that rotates about the E axis, and a coating gun 9. And a shaft 13 that rotates the shaft around the F axis. The cases 11 and 12 and the shaft 13 are individually driven by motors 14 to 16 attached to the base end portion of the second arm 6. The rotational driving forces of the motors 14 to 16 are transmitted to the cases 11 and 12 of the wrist portion 7 through transmission mechanisms (not visible in FIG. 1) provided inside the second arm 6 and the wrist portion 7. It is transmitted to the shaft 13.
[0015]
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 the robot controller 17. The Each joint portion of the industrial robot 1 incorporates an encoder (not shown) for detecting the angle of each movable part, and the robot controller 17 feeds back a detection signal output from the encoder. Thus, each of the motors is controlled to accurately drive the turning base 4, the first arm 5, the second arm 6, and the wrist portion 7.
[0016]
On the second arm 6, a color changing valve unit 18 is attached. The coating gun 9 is connected to the color changing valve unit 18 through the paint supply tube 19.
In addition, a plurality of paint supply tubes 20 are connected to the color change valve unit 18, and the paints of the respective colors are supplied through the paint supply tubes 20. Each valve of the color change valve unit 18 is selectively controlled by a color change control device (not shown) provided in the robot controller 17 and selectively supplies the designated paint to the paint gun 9.
[0017]
Here, the reference example 1 is demonstrated about the structure of the transmission mechanism provided in the inside of the 2nd arm 6 and the wrist part 7. FIG. An embodiment that solves the above-described problem most effectively will be described later, but the following Reference Examples 1 and 2 will be described on the assumption that the above-described problem can be solved. FIG. 2 is a longitudinal sectional view showing the internal structure of the second arm 6 and the wrist portion 7. The 2nd arm 6 is formed in the hollow shape, and the motors 13-15 which drive each axis | shaft of the wrist part 7 are attached to the rear end. The motors 13 to 15 are protected by a cover 21 attached to the rear end of the second arm 6.
[0018]
The output shafts of the motors 13 to 15 are connected to rods 22 to 24 that extend along the second arm 6. The rods 22 to 24 extend in parallel and are held so as not to interfere with each other. Thus, since the inside of the 2nd arm 6 is the structure by which the three rods 22-24 are extended in parallel, it can aim at weight reduction significantly rather than what attaches a torque tube concentrically. This is possible, and the rigidity of the second arm 6 can be lowered. Therefore, the thickness of the second arm 6 can be reduced to reduce the weight of the second arm 6 itself.
[0019]
The motor 13 constitutes a first drive unit that drives the case 11 around the D axis, the motor 14 constitutes a second drive unit that drives the case 12 around the E axis, and the motor 15 configures the shaft 13 as the F axis. A third drive unit for driving around is configured.
Further, bearing units 28 to 30 that support the rods 25 to 27 are held at the front end of the second arm 6. 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.
[0020]
The bearing units 28 to 30 each have a pair of bearings 31 and 32, and the bearing units 28 and 30 are supported by brackets 34 and 35 with a spacer 33 interposed between the bearings 31 and 32. The bearing unit 29 has a pair of bearings 31 and 32 held by an annular pressing plate 36.
[0021]
FIG. 3 is a longitudinal sectional view of the inside of the first case 10 as seen from the axial direction of the second arm.
Worms 37 and 38 as spiral engaging portions are provided at the ends of the rods 25 and 27. In addition, rods 25 to 27 protrude inside the first case 10. And the drive pulley 40 is attached to the rod 26 at the end.
[0022]
A rod 41 is arranged in parallel with the rod 26 and is supported by a bearing unit 42. The bearing unit 42 is held by a bracket 43 fixed inside the first case 10. The rod 41 has a driven pulley 44 attached to one end and a bevel gear 45 attached to the other end. A timing belt 46 is wound around the outer periphery of the driving pulley 40 and the driven pulley 44.
[0023]
Accordingly, the rotational driving force of the motor 14 is transmitted to the rods 23 and 26, the driving pulley 40, the timing belt 46, the driven pulley 44 and the rod 41.
Also, worm wheels 47 and 48 that mesh with the worms 37 and 38 are provided inside the first case 10. The worm wheels 47 and 48 are provided at end portions of hollow shafts 49 and 50 extending in a direction orthogonal to the extending direction of the worms 37 and 38. The worms 37 and 38 extend in the tangential direction of the worm wheels 47 and 48, and teeth formed in a spiral shape on the outer periphery of the worm wheels 37 and 38 are formed in a spiral shape on the outer periphery of the worm wheels 47 and 48. Meshed with teeth.
[0024]
A rod 51 is inserted through the through hole of the inner shaft 50. The rod 51 is supported by bearings 52 provided at both ends of the through hole of the shaft 50. A bevel gear 53 that meshes with the bevel gear 45 of the rod 41 is attached to one end of the rod 51, and a bevel gear 54 is attached to the other end of the rod 51.
[0025]
The shaft 50 is supported by bearings 55 provided at both ends of the through hole of the shaft 49. A worm wheel 48 is attached to one end of the shaft 50, 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 at 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 provided so as to rotate integrally with the shaft 49.
[0026]
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. The shaft 59 and the shaft 61 are arranged coaxially and are supported by bearings 62 and 63, respectively. The end portion of the shaft 61 is coupled to the side surface of the third case 12. Accordingly, the third case 12 rotates integrally with the shaft 61.
[0027]
In addition, a shaft 66 having a bevel gear 65 meshing with a bevel gear 64 provided at the other end of the shaft 59 is provided inside the third case 12, and the shaft 66 is rotated on the lower surface of the third case 12. A reduction gear 67 that decelerates is provided. 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.
[0028]
As described above, since the rotation of the rods 22 and 24 is transmitted to the second case 11 and the third case 12 through the worms 37 and 38 and the worm wheels 47 and 48 inside the first case 10. The weight can be reduced as compared with the conventional configuration in which the torque tubes are arranged concentrically. As a result, the rigidity of the second arm 6 can be reduced to reduce the weight of the second arm 6 itself. As a result, the capacity of the motor that drives the second arm 6 can be reduced. Miniaturization can be achieved.
[0029]
Further, since the worms 37 and 38 having spiral teeth are always meshed with the worm wheels 47 and 48, even if the motors 13 and 15 are turned off, the worm wheels 47 and 48 rotate freely. There is no need to provide a brake mechanism for the motors 13 and 15.
[0030]
In addition, although the shafts 49 and 50 provided in the first case 10 are formed in a hollow shape, they cannot be configured as rods in terms of 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 is driven by the motor 13 and rotates around the D axis.
[0031]
Further, the rotational driving force of the motor 14 includes the rods 23 and 26, the driving pulley 40, the timing belt 46, the driven pulley 44, the rod 41, the bevel gears 45 and 53, the shaft 51, and the bevel gear that constitute the second transmission mechanism. 54 and 58, the shaft 59, the bevel gears 64 and 65, the shaft 66, the speed reducer 67, and the shaft 13 are transmitted to the coating gun 9. In this way, the shaft 13 is driven by the motor 14 and rotates around the F axis.
[0032]
The rotational driving force of the motor 15 is transmitted to the third case 12 via the rods 24 and 27, the worm 38, the worm wheel 48, the shaft 50, the bevel gears 56 and 60, and the shaft 61 that constitute the third transmission mechanism. The Thus, the third case 12 is driven by the motor 15 and rotates around the E axis.
[0033]
4 and 5 show a reference example 2 of the present invention. The reference example 2 is different from the reference example 1 described above in that screws 37A and 38A are used instead of the worms 37 and 38, and screw gears 47A and 48A are used instead of the worm wheels 47 and 48. Accordingly, the screws 37A and 38A extend in the tangential direction of the screw gears 47A and 48A, and a screw thread formed in a spiral shape on the outer periphery of the screws 37A and 38A is formed in a spiral shape on the outer periphery of the screw gears 47A and 48A. Meshed with the teeth.
[0034]
Accordingly, the rotational driving force of the motor 13 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 first transmission mechanism. Thus, the second case 11 is driven via the screw 37A and the screw gear 47A and rotates around the D axis.
[0035]
The rotational driving force of the motor 15 is transmitted 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 that constitute the third transmission mechanism. The In this way, the third case 12 is driven via the screw 38A and the screw gear 48A and rotates around the E axis.
[0036]
Thus, in the configuration of Reference Example 2 , 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. The weight can be reduced as compared with the conventional configuration in which the torque tubes are arranged concentrically. As a result, the rigidity of the second arm 6 can be reduced to reduce the weight of the second arm 6 itself. As a result, the capacity of the motor that drives the second arm 6 can be reduced. Miniaturization can be achieved.
[0037]
Furthermore, since the screws 37A and 38A having spiral threads are always meshed with the screw gears 47A and 48A, even if the motors 13 and 15 are turned off, the screw gears 47A and 48A rotate freely. There is no need to provide a brake mechanism for the motors 13 and 15.
[0038]
6 and 7 show an embodiment of the present invention. In the embodiment , the difference from the reference example 1 described above is 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. is there.
[0039]
The rods 22 to 24 connected to the output shafts of the motors 13 to 15 are connected to the worms 37 to 39 via the rods 25 to 27. Each of the worms 37 to 39 extends in parallel and extends in a tangential direction of the worm wheels 68, 47, and 48.
[0040]
The worm wheels 68, 47, 48 are provided at the ends of shafts 49 to 51 extending in a direction orthogonal to the extending direction of the worms 37 to 39. The shafts 49 to 51 are provided coaxially, and the total length is set to a length corresponding to the interval between the worms 37 to 39. The worms 37 to 39 extend in the tangential direction of the worm wheels 68, 47 and 48, and the teeth formed in a spiral shape on the outer periphery of the worm wheels 37 to 38 are spiral on the outer periphery of the worm wheels 68, 47 and 48. Meshed with the teeth formed on.
[0041]
Accordingly, in 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. The weight can be reduced as compared with the conventional configuration in which the torque tubes are arranged concentrically. As a result, the rigidity of the second arm 6 can be reduced to reduce the weight of the second arm 6 itself. As a result, the capacity of the motor that drives the second arm 6 can be reduced. Miniaturization can be achieved.
[0042]
Furthermore, since the worms 37 to 39 having spiral teeth are configured to always mesh with the worm wheels 68, 47, and 48, the worm wheels 68, 47, and 48 are not affected even if the motors 13 to 15 are turned off. The motors 13 to 15 do not need to be provided with a brake mechanism.
[0043]
As shown in FIG. 7, the worms 37 and 39 mesh with the left side of the worm wheels 68 and 47, and the intermediate worm 38 meshes with the left side of the worm wheel 48 so that the worms 37 to 39 do not interfere with each other. It is arranged.
Here, the operation of the transmission mechanism configured as described above will be described.
[0044]
The rotational driving force of the motor 13 is transmitted to the second case 11 through the rods 22 and 25, the worm 37, the worm wheel 47, and the shaft 49 that constitute the first transmission mechanism, as in the first reference example . Thus, the second case 11 is driven by the motor 13 and rotates around the D axis.
[0045]
The rotational driving force of the motor 14 is transmitted to the third case 12 via the rods 23 and 26, the worm 38, the worm wheel 48, the shaft 50, the bevel gears 56 and 60, and the shaft 61 constituting the second transmission mechanism. The Thus, the third case 12 is driven by the motor 14 and rotates around the E axis.
[0046]
Further, the rotational driving force of the motor 15 includes the rods 24 and 27, the worm 39, the worm wheel 68, the shaft 51, the bevel gears 54 and 58, the shaft 59, the bevel gears 64 and 65, the shaft 66, and the third transmission mechanism. This is transmitted to the coating gun 9 via the speed reducer 67 and the shaft 13. In this way, the shaft 13 is driven by the motor 14 and rotates around the F axis.
[0047]
In the above-described embodiment, an industrial robot having a configuration in which the coating gun 9 is mounted on the tip of the wrist portion 7 has been described as an example. However, the present invention is not limited to this, and the present invention can also be applied to a robot mounted with other jigs. Of course.
[0048]
【The invention's effect】
As described above, according to the present invention, the wrist portion 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 is unnecessary. Since the rods can be arranged in parallel, the transmission mechanism can be made lighter than the configuration using the torque tube. As a result, it is possible to reduce the rigidity of the arm, so that the thickness of the arm itself can be reduced and the weight can be reduced, and accordingly, the arm driving motor can be reduced in size. In addition, when the motor is stopped, the spiral engaging portion becomes non-rotatable, so that even if the power is turned off, the wrist portion can be prevented from rotating freely by its own weight, and the motor brake can be dispensed with.
[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 Reference Example 1 of a transmission mechanism for driving a wrist portion.
3 is a longitudinal sectional view of the inside of the first case shown in FIG. 2 as viewed from the axial direction of a second arm. FIG.
FIG. 4 is a longitudinal sectional view of a second arm provided with a reference example 2 of a transmission mechanism for driving a wrist portion.
FIG. 5 is a longitudinal sectional view of the inside of the first case shown in FIG. 4 as viewed from the axial direction of the second arm.
FIG. 6 is a longitudinal sectional view of a second arm provided with an embodiment of a transmission mechanism for driving the wrist.
7 is a longitudinal sectional view of the inside of the first case shown in FIG. 6 as viewed from the axial direction of the second arm. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Industrial robot 3 Base 4 Turning base 5 1st arm 6 2nd arm 7 Wrist part 9 Paint 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)

A wrist portion having three mutually orthogonal axes, and three motors for driving each axis of該手neck, a transmission mechanism for transmitting the rotational driving force of the three motors for each axis of the wrist portion, the distal end In an industrial robot having the wrist portion and an arm having the three motors at the rear end,
The transmission mechanisms are respectively connected to the output shafts of the three motors, extend along the arms so as not to interfere with each other, and are supported by bearings near the tips in the arms and supported by the bearings. 3 rods provided on the outer periphery with three rods attached with worms extending to the tip of the portions, and helical teeth meshing tangentially with the worms of the three rods. An industrial robot comprising two worm wheels.

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