JPS5882689A - Balancer for inductrial robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrial robot, and more particularly to means for applying a lifting force to a lifting frame that moves up and down in proportion to the load thereof, thereby reducing the power of the drive source of the lifting frame.

Generally, industrial robots with a cylindrical coordinate system or a rectangular coordinate system are equipped with a vertically movable lifting frame.

The lifting frame supports the arm and robot hand,
Move up or down while holding an object. During this movement, a large driving force is required due to the weight of the lift frame itself and the object being gripped, which also increases the size of the components of the robot and the waste of energy cannot be ignored.

Therefore, a balance device is used in this type of industrial robot, and the balance device applies an upward force to the lift frame that corresponds to the weight of the lift frame and the object to be grasped. It works to reduce the power of the drive source.

This type of balance device includes a balance weight system and a weight balance system using a coil spring and a balance cylinder. The balance weight method uses a weight corresponding to the weight of the lifting frame and the object to apply an upward force to the lifting frame to keep them in a balanced state. Industrial robots that move quickly require a large amount of surface power, and it is impossible to automatically adjust the balance state according to the weight of the object being grasped. It is not an effective method for advanced industrial robots. On the other hand, when using one type of balance cylinder, although there is an advantage that the device can be made smaller,
A fluid pressure generating device and an automatic fluid pressure adjusting device are required to drive the cylinder, and the installation space for these devices is quite large, and the amount of energy consumed during operation is not negligible.

Another type of balance device has been proposed, in which the thrust of the cylinder is converted into torque using a screw or cam mechanism, and this is balanced against the torque caused by the gravity of the lifting frame. This is similar to the balance cylinder one-type system in that it requires a fluid pressure generating device and an automatic adjustment device for driving the cylinder. Furthermore, with the coil spring method or the balance weight method, it is impossible to automatically compensate for the gravity of the object to be gripped.

The present invention provides a balance device with a new concept that solves the above problems, prevents the device from increasing in size, and consumes only a small amount of power during operation to adjust only the gravity balance of the gripped object. Particularly, the object of the present invention is to provide an ideal balance device that can maintain a state as close to zero gravity as possible, including the gravity of the object being held, especially during manual direct teaching.

Hereinafter, the present invention will be explained in detail based on an embodiment shown in the drawings.

First of all, Figure 1 shows an example of a cylindrical coordinate type industrial robot l.
It shows. This industrial robot 1 has a turning table 3 mounted on a base 2 so as to be driven by a turning servo motor 4, and an elevating frame 5 mounted on the turning table 3 so as to be able to rise and fall freely. This elevating frame 5 has a telescopic arm 7 driven by a telescopic mower, and this arm 7 is rotatable at its end and equipped with a robot hand 9 capable of gripping an object 8. The power industrial robot 1 is placed under the control of a control device 1O, and programs necessary for operation can be inputted via an operation panel 11.

The above lift frame! As shown in Fig. 2, Fig. 3, a pair of guide bars 1 are installed upright on a rotating table 3.
2, and is raised or lowered by the rotation of the feed screw 13, which is a ball screw located at the center. The pair of guide bars 12 support an upper frame 14 at their upper portions, and the upper frame 14 holds at its upper portion a servo motor 15 as a drive source for raising and lowering. This servo motor 1
The rotation of 5 is transmitted to the feed screw 13 via a clutch 16 and gears 17 and 18. The upper part of the feed screw 13 is the upper frame 1
Two bearings 21, 22 are installed inside the bearing housing It of 4.
The upper bearing 11 is held by the upper K If of the detector 20 such as a load cell, and the lower bearing 2
2H supports the detector 20a on its upper surface. Therefore, the load applied to the feed screw 13 can be detected by the detector 20. The amount of rotation of the feed screw 13 is detected by an encoder 23 or the like and sent to the control device 10. A balancer 24 is attached above the upper frame 14. This balancer 24 has a drive shaft 26 inside a casing 25 as shown in FIG. It is equipped with a spiral spring 27 and a conical pulley 2B as a spring for the parannu. The drive shaft 26 is rotatably supported by a bearing 29 with respect to the casing 25, and a worm wheel 30 provided at one end of the drive shaft 26 meshes with a worm gear 31K in an orthogonal position. This worm gear 31 is connected to a servo motor 33 via an adjustment shaft 32. These servo motor 33 and worm gear mechanism (worm wheel 30, worm gear 31) constitute a spring driving means. The spiral spring 27 is housed inside a spring case 34, and one end of the spiral spring 27 is connected to the drive shaft 27.
The other end is indirectly fixed to the conical pulley 2B via the spring case 34t. This conical pulley 28 is rotatably supported by a bearing 35 with respect to the drive shaft 26, and is provided with a spiral wire groove 37 along the conical surface for winding a lifting wire 36 around its outer periphery. The radius of this wire groove 37 becomes smaller toward the tip, and this is to compensate for the change in the elastic resistance of the spiral spring 27 depending on the winding condition. One end of the wire 36 is connected to the conical pulley 28 at the large diameter portion of the wire groove 3f.
The other part is guided to the outside from the guide hole 38 of the casing 250 and is attached to a guide roller 39. which is attached to the upper frame 14. 2 attached to the lifting frame 5
After being wrapped around two movable pulleys 41, 42 and a fixed pulley 40 attached to the upper frame 14, it is fixed to a fixing pin 43 fixed to the lifting frame 5 with a wire support 44. Note that a cover 4 is installed between the turning table 3 and the upper frame 14.
A bellows 46 is attached between the lifting frame 5, the upper frame 14, and the turning table 3, and the internal mechanism is protected by these bellows.

Next, the function and operation will be explained. In the stationary state, the spiral spring 27 of the balancer 24 acts on the wire 36 with a lifting force that balances the weight of the lifting frame 5, and the lifting frame 5
is lifting up. Therefore, the weight of the lifting frame 5, arm 7, etc. is hardly applied to the feed screw 13.

The pulling force or balancing force of the spiral spring 27 can be sufficiently withstood even if the spiral spring 27 of the pulley mechanism is relatively small. To adjust the balance force in this stationary state, adjust the adjustment axis 3.
This can be easily done from the outside by rotating 2 in the appropriate direction.

Now, when the industrial robot 1 starts moving and the robot hand 9 grasps and lifts an object, a load equivalent to the weight of the object 80 is applied to the lifting frame 5. This load of the lifting frame 5 is applied to the detector 20 via the feed screw 13.

The detector 20 then generates an analog signal proportional to the increased weight.

It is sent to the control device 10. This and color control device lO
is the servo motor 3 in the direction to cancel this change in detection output.
Drive 3. The rotation of the servo motor 33 is controlled by the worm gear 31. It is transmitted to the adjustment shaft 32 via the worm wheel 30 and winds the spiral spring 27. Accordingly, the balance force of the spiral spring 27 increases by an amount corresponding to the increased load of the lifting frame 5. When the balance adjustment is completed in this way, the output (analog value) of the detector 20 becomes zero, so the servo motor 33Fi automatically stops.

In contrast to the above operation, when the industrial robot (1 ps) object 8 is placed at a predetermined position, the balanced state becomes overbalanced. The condition of this paddy is detected by the detector 208K.
The balance force of the spiral spring 27 is detected and sent to the control device IO, so that the control device IO issues a signal to reduce the balance, reverses the servo motor 33, and unwinds the spiral spring 27. In this way, the balance force of the spiral spring 27 is raised and lowered. It decreases in response to the reduced load on the frame 5. Furthermore, when the lifting frame 5 starts to rapidly ascend or descend, or stops moving, the detector 20 or the detector 20α detects the inertia force each time, resulting in unnecessary balance adjustment. Therefore, the control device IO at that time detects the detectors 20 and 2.
Control conditions are set to ignore the detection output of 0g. Also, worm wheel 3° and worm gear 31
Since it is in a self-supporting state, the adjustment shaft 32 is rotated by the load of the lifting frame 5 or the force of the spiral spring 27 after balance adjustment.

Although the above embodiment employs a spiral spring 27 as a balance spring, this spring can also be constructed of a coil spring or the like, and the lifting frame 5 can be lifted without using a wire 36 or a pulley mechanism. It is also possible to lift it directly.

Further, although the detectors 20 and 20α are constructed of two pressure sensors, they may be composed of one pressure sensor or a completely different detection method.

According to the present invention, the entire configuration of the balance device can be provided compactly and inexpensively, and all balance adjustments can be made automatically and can respond to large changes in the weight of the conveyed object, allowing industrial robots to move smoothly and quickly. Moreover, an industrial robot with low energy consumption can be produced because a particularly complicated fluid pressure regulating device is not required and the energy loss for each operation is minimized.

[Brief explanation of the drawing]

FIG. 1 is a front view of the industrial robot of the present invention, FIG. 2 is a vertical sectional view of the driving part of the lifting frame as seen from the side, FIG. 3 is a vertical sectional view of the driving part of the lifting frame as seen from the front, and FIG. The figure is a sectional view of the balancer. l...Industrial robot, 5...Lifting frame, 7.
··arm. 8...Object% 9...Four pot hand, 10
...Control device, 13--Feed screw, 20,2
0α...Detector. 24... Balancer, 27... Spiral spring, 28
... Conical pulley, 30 ... Worm wheel, 31
... Worm gear, 33-... Servo motor, 36.
...Wire. Figure 2

Claims (2)

[Claims] (1) In an industrial robot consisting of a lifting frame with a robot hand supported so as to be able to rise and fall freely by a feed screw and its drive source, the lifting frame is lifted by a balance spring and the load on the lifting frame is detected. Detected by a detector, and actuated a control device by the output of this detector,
A balance device characterized in that a spring driving means is driven by the control output of the control device, and the spring driving means causes the elasticity of the spring to correspond to the load of the lifting frame and the object gripped by the robot hand. (2) The above-mentioned balance spring is composed of a spiral spring, and the above-mentioned spring driving means is a servo motor! The balance device according to claim 1, characterized in that it is constructed by a worm gear mechanism.