JPH0890484A - Industrial robot provided with permanent magnet type balancer - Google Patents

Abstract

PURPOSE: To provide an industrial robot provided with a balancer at a low cost capable of producing a large balance moment. CONSTITUTION: As a balancer 30 mounted on robot machine bodies 7, 9 to reduce and balance load moment applied to a drive motor 8 of a robot arm or the like, an industrial robot is constituted by providing the permanent magnet type balancer 30 producing the balance moment M2 by balancing balance force produced in accordance with a turn angle of the robot arm 9 and magnetic force of permanent magnets 34, 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancer of an industrial robot, and more particularly, to a balance moment of a permanent magnet that balances and reduces a load moment applied to a drive motor of a movable element in the industrial robot according to the robot motion of the movable element. The present invention relates to the structure of a balancer generated by utilizing magnetic force.

[0002]

2. Description of the Related Art An industrial robot, especially a vertical articulated robot, has a robot arm extending from a robot torso standing upright on a robot base to an upper arm side arm and a forearm side arm. It has a configuration in which the end is connected to the front end of the robot arm on the upper arm side via a joint. In addition, a wrist is provided at the tip of the robot's forearm side, and an end effector such as a robot hand is detachably attached to this wrist. For example, the robot hand grips and conveys a work, or a work assembling work. And the like.

In the above-described vertical articulated robot, the upper arm side robot arm is rotated around the joint axis of the arm base by the drive motor attached to the upper region of the robot body, and the forearm side robot arm is the upper arm side. The robot arm is rotated around the joint axis by a drive motor attached to the upper end of the robot arm. Therefore, in particular, the weight of all elements including the robot arm on the upper arm side, the robot wrist, the end effector, etc. acts as a load on the drive motor for rotating the robot arm on the upper arm side. When the work is held via the effector, the work weight also acts as a load. As a result, these weights act as load moments that vary according to the posture of the upper arm robot arm and act on the drive motor of the upper arm robot arm, so that the weight between the upper end of the robot body and the upper arm robot arm is generally increased. A balancer is provided to generate a balance moment for reducing the load moment to reduce the load applied to the drive motor of the upper arm robot arm.

FIG. 5 and FIG. 6 show the surrounding structure centering on the upper arm side robot arm of a vertical articulated robot equipped with a conventional balancer, and the balancer 12 has one end 12a thereof.
Is fixed to the upper end 7a of the robot body 7, and the other end 12b is fixed to an appropriate position of the upper arm side robot arm 9. At this time, the drive motor 8 that causes rotation of the upper arm side robot arm 9 is attached to the joint 7b of the robot body 7, and the forearm side robot arm is connected via the joint 10 provided at the tip of the upper arm side robot arm 9. 11 is the joint 1
It is provided rotatably around the axis of zero.

In the state shown in FIG. 5 in which the upper arm robot arm 9 is in the vertical posture, the load moment due to gravity with respect to the drive motor 8 has a moment arm length from the axial center of the joint 7b to the point of gravity action of zero. Therefore, the same load moment is also zero. However, when the upper arm side robot arm 9 is rotated about the axis of the joint 7b through the angle θ as shown in FIG. 6, gravity acting on the front end of the upper arm side robot arm 9 intensively acts. If the load is mg and the fixed distance between the shaft centers of both joints 7b and 10 is (L1),
The load moment (M1) acting on the drive motor 8 is M1 = L1 × mg × sin θ (1)

Therefore, the balancer 12 equilibrates the one end 12b with the balance force F so as to reduce the load moment (M1).
Is applied, the equilibrium moment (M2) generated around the axial center of the joint 7b by the equilibrium force F causes the fixed distance between the fixing point 12b of the balancer 9 and the joint 7b to be L2,
Further, when the attitude angle of the balancer 9 is α, the following equation (2) is obtained.

M2 = L2 × F × cos α (2) Therefore, if the balancing force F is generated so that M1 = M2, the load moment M1 applied to the drive motor 8 can be reduced. However, as shown in FIGS. 3 and 4, the conventional balancer 12 has a linearly moving rod 16 having a disk-shaped head portion 15 in a hollow cylindrical spring container 14 and a cylindrical coil spring 17. It has a structure of being housed inside the spring container 14. Then, one end of the spring container 14 is used as the balancer end 12a described above, and one end of the linear motion rod 16 is used as the balancer end 12b described above, which is arranged between the robot body 7 and the upper arm side robot arm 9. .

In the balancer 12 using the cylindrical coil spring 17 as described above, as shown in FIG. 4, the linearly moving rod 16 is linearly displaced with respect to the spring container 14 in accordance with the rotation of the upper arm robot arm 9. By compressing the cylindrical coil spring 17, an equilibrium force F that increases or decreases according to the amount of compression (length) is generated. Therefore, the equilibrium force F due to such spring compression is used to obtain the load moment reducing moment M2 in the above equation (2).

[0009]

As described above, when the cylindrical coil spring 17 is used, a relatively large balancing force F can be generated, but in recent years, the robot grips with a robot hand at the tip or the like. The load applied to the drive motor 8 of the upper arm robot arm 9 due to an increase in the transportable weight including a request for an increase in the work weight and an increase in the movable range in the three-dimensional space where the vertical articulated robot operates. Since the moment increases more and more, it is inevitably required to reduce the balancer 12 and increase the equilibrium moment.

However, in the balancer 12 using the cylindrical coil spring 17, in order to increase the balance force F,
The cylindrical coil spring 17 needs to be strengthened.
In order to strengthen the spring generation force of, it is inevitably necessary to increase the diameter of the coil forming material and the coil diameter. That is, if the spring displacement is the same when trying to strengthen the spring, in order to increase the amount of internal stress (kx: k spring constant, x displacement) generated in the spring material, the diameter of the spring material and the coil diameter must be increased. Etc. must be increased.

As described above, when the size of the cylindrical coil spring 17 is increased, the size and weight of the balancer 12 are also increased,
As a result, since the balancer 12 rotates around the joint 7b integrally with the upper arm robot arm 9, the load moment M1 to the drive motor 8 increases, which is disadvantageous. are doing. in addition,
In the configuration using the cylindrical coil spring 17, in addition to the generation of the spring force along the spring axis when the spring is compressed or pulled, a torsional force around the axis is often generated. Conventionally, such a torsional force has been configured to be received by providing bearings at both ends 12a and 12b of the balancer 12, but this complicates the structure of the bearing portion, which in turn increases the cost of the balancer 12. There was also a disadvantage.

On the other hand, although a balancer using a cylinder device has already been provided, since the cylinder device is expensive, there is a disadvantage that the cost of the robot itself increases due to the cost increase of the balancer of the robot. Therefore, in view of the above-mentioned problems, an object of the present invention is to provide an industrial robot,
In particular, in order to provide a balancer for reducing and balancing the load moment, which can be provided on the robot body in a relatively compact form in response to a request for an increase in load load that can be handled and processed by a vertical articulated robot. is there.

Another object of the present invention is to provide a balancer which can be realized at a low cost and at the same time can exhibit a large balance moment in spite of being relatively small in size in accordance with the payload of the robot and the expansion of the movable range. To provide industrial robots.

[0014]

In view of the above-described object of the present invention, the present invention is mounted on a robot body to reduce and balance load moments mainly applied to an arm drive motor on the proximal end side of a robot arm. As a balancer,
(EN) An industrial robot having a balance that generates a balance moment by utilizing a magnetic force of a permanent magnet, particularly a repulsive force, as a balance force generated according to a rotation angle of a robot arm.

According to the present invention, in an industrial robot provided with a balancer for generating a balance moment for reducing a load moment that increases or decreases according to a robot motion of a driven element by a drive motor, the balancer is provided in the driven element. A first magnet holder that is fixed and holds a permanent magnet, and a second magnet holder that is fixed to a mounting portion of the drive motor and that holds a permanent magnet facing the permanent magnet of the first magnet holder. Magnet retainer, which induces an increase / decrease in magnetic force of the permanent magnet according to the approach and separation of the first and second magnet retainers corresponding to the robot motion of the driven element, and generates a moment for canceling the load moment. An industrial robot provided with a permanent magnet type balancer having the above-mentioned configuration.

The first magnet holder has a disk-shaped head at one end of the rod-shaped element and at the same time has a fixed end for the driven element at the other end, and the head has a disk-shaped shape. Has a structure in which the permanent magnet pieces are fixedly held, and the second magnet holder is
An outer end formed on the hollow cylindrical container element has a fixed end to the mounting portion of the drive motor, and a magnetic repulsive force is generated in the container with the permanent magnet of the first magnet holder. A permanent magnet type having a structure in which a permanent magnet is fixedly held so that the first rod-shaped magnet holder is inserted so as to be linearly movable in the second cylindrical magnet holder. It is preferably balanced.

[0017]

According to the permanent magnet type balance having the above configuration, when the driven element in the robot body of the industrial robot, for example, the upper arm side robot arm rotates with respect to the robot body and is displaced to the load moment generating position. , The first rod-shaped magnet holder in the balancer moves linearly inside the second hollow cylindrical magnet holder, and when the permanent magnets in both holders approach each other, a gradually increasing magnetic force (magnetic repulsion force) is generated. A balance moment that reduces the load moment is generated.

At this time, the magnetic force of the permanent magnets held by the first and second magnet holders can generate a destructive moment corresponding to the maximum load moment within the variation range of the load moment generated on the robot body side. As described above, if the magnetization level for the permanent magnet is adjusted in advance and the magnetization is performed,
It is possible to generate a large magnetic force even if the permanent magnet elements have the same size. Therefore, the permanent magnet type balancer has an advantage that the increase or decrease of the load moment reducing moment generated by the permanent magnet type balancer can be adjusted by increasing or decreasing the magnetization amount of the permanent magnet, and therefore the balancer does not become large. I have it.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A permanent magnet balancer according to an embodiment of the present invention, which is mounted on the body of an industrial robot, in particular, a vertical articulated robot to balance load moments, will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an internal structure of a permanent magnet type balancer according to an embodiment of the present invention,
FIG. 2 is a cross-sectional view showing a state in which the balancer is displaced in order to generate a load moment reducing moment.

In FIGS. 1 and 2, a permanent magnet type balancer 30 is provided with a magnet holder 32 having a hollow cylindrical bottomed container shape, and the magnet holder 32 has an ear end protruding outside the bottom portion thereof. 32a is provided as a fixed end to the robot body, and a disk-shaped permanent magnet piece 34 is held on the open end side of the magnet container 32. Here, the permanent magnet piece 34 has a through hole 34a in the center, and has a structure in which it is communicated with the inside of the container together with the opening of the magnet holder 32.

The balancer 30 further includes the magnet holder 3 described above.
2 is provided with a rod-shaped element 36 inserted so as to be directly movable, and the rod-shaped element 36 is provided with a head 38 having a disc shape on the inner bottom side of the magnet holder 32. The disk-shaped permanent magnet 40 is fixed and held. At this time, the permanent magnet 34 held by the cylindrical magnet holder 32 and the permanent magnet 40 held by the head portion 38 of the rod-shaped element 36 described above have a magnetic repulsive force F that gradually increases when the two approach each other. Are arranged so that the same poles face each other so as to generate.

The outer end 36a of the rod-shaped element 36 is formed as a fixed end to the robot body. Therefore, the balancer 30 according to the present embodiment is the same as the conventional one shown in FIGS. Similar to the balancer 12, for example, the fastening end 32a is fastened to the one end 7a of the robot body 7 of the vertical articulated robot, and the fastening end 36a is fastened to the upper arm robot arm 9 at a proper position. As a result, it is possible to generate a balance moment that reduces the load moment on the drive motor 8.

That is, the robot arm 9 on the upper arm side has the joint 7
When rotating around b, the rod-shaped element 36 of the balancer 30 is linearly displaced from the inner bottom side of the cylindrical magnet container 32 to the opening side as shown in FIG. As a result, both cages 3
The permanent magnet pieces 34 and 40 held by 2 and 36 approach each other to increase the magnetic repulsive force, and therefore increase and generate the balance moment according to the above-described equation (2).

Of course, if permanent magnets 34, 40 are magnetized and used with sufficiently strong magnets, it is possible to generate a compact and strong balance force. Further, in comparison with the conventional balance in which a cylindrical coil spring is compressed, even if the thickness of the permanent magnet pieces 34, 40 in the direction of linear motion is smaller than the length of the spring, a large balance force can be generated by a large magnetic force. Therefore, it is possible to configure a balancer in which the linear movement stroke of the rod-shaped element 36 is large. This is effective in generating a large balance moment as a moment for reducing the load moment when the movable range of the robot increases.

In addition, since the magnetic repulsive force acting between the permanent magnet pieces 34, 40 is only the force component acting in the axial direction of the rod-shaped element 36, the torsion is different from the case of using the cylindrical coil spring. There is no need for bearing arrangements that compensate for the generation of forces. As a result, the fastening ends 32 at both ends of the balancer 30 are
As a result, the structures of a and 26a can be simplified, which in turn contributes to cost reduction.

[0026]

As is apparent from the above description, according to the present invention, the balancer mounted on the robot body reduces and balances the load moment mainly applied to the arm drive motor on the proximal end side of the robot arm. As an industrial robot provided with a balance that generates a balance moment by using a magnetic force of a permanent magnet as a balance force generated according to a rotation angle of a robot arm, a balancer using a conventional cylindrical coil spring is provided. It is possible to increase the balance moment in accordance with an increase in the loadable weight of the robot and an increase in the robot movable range, while avoiding an increase in the size of the balancer as compared with the industrial robot used.

As a result, the load on the drive motor on the robot body can be reduced, so that the transportable weight of the robot can be increased and at the same time the speeding up of the robot movement can be promoted. Moreover, the structure of the balancer realizes a reduction in the number of parts and a further simplification of the structure, as is obvious from the above description of the structure.
It is possible to improve the operational reliability while reducing the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an internal structure of a permanent magnet type balancer according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the balancer is displaced in order to generate a moment for canceling a load moment.

FIG. 3 is a cross-sectional view showing an internal structure of a balancer using a conventional cylindrical coil spring.

FIG. 4 is a cross-sectional view showing a state where the conventional balancer is displaced to generate a load moment reducing moment.

FIG. 5 is a partial front view showing a configuration of a robot body and a robot arm of a vertical articulated robot and an arrangement of a balancer.

FIG. 6 is a partial front view illustrating a state in which the balancer is operating by the rotation of the upper arm robot arm of the robot.

[Explanation of symbols]

 7 ... Robot body 7b ... Joint 8 ... Drive motor 9 ... Upper arm side robot arm 10 ... Joint 11 ... Forearm side robot arm 30 ... Permanent magnet type balancer 32 ... Magnet holder 34 ... Permanent magnet piece 32a ... Fixed end 36 ... Rod -Shaped element 36a ... Fixed end 38 ... Head 40 ... Permanent magnet 40

Claims (1)

[Claims] 1. In an industrial robot having a balancer for generating a balance moment that reduces a load moment that increases and decreases according to a robot motion of a driven element by a drive motor, the balancer is fixed to the driven element. A first magnet holder that holds a permanent magnet, and a second magnet holder that holds a permanent magnet that is fixed to the mounting portion of the drive motor and that faces the permanent magnet of the first magnet holder. To induce increase and decrease in the magnetic force of the permanent magnets in accordance with the approach and separation of the first and second magnet holders corresponding to the robot movement of the driven element, and to generate a moment for canceling the load moment. An industrial robot having a permanent magnet type balancer, which is characterized by having the above-mentioned configuration.