JPS60131182A - Balancer for industrial 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 Field of Industrial Application The present invention relates to two members that are mutually rotatably supported by a shaft and form a joint structure. The present invention relates to a balance device for a joint swivel having a structure in which such torque changes.

Structure of conventional example and its problems An example of a conventional balance structure around a joint is shown in the 11th page 1. In Figure 1, two members forming a joint structure (hereinafter referred to as arms, and referred to as the Lou arm and the second arm)
The first arm 1 and the second arm 2 are connected by a shaft 3. A spring 4 is hung on the shaft 3, and weights 96 are attached to both ends through a spring 6. The part 4 shift is fixed to the first arm 1 between the spring 5 and the main part, and serves to support the main part only when the spring 5 is extended to the second part.

The operation shown in FIG. 1 will be explained. If the second arm 2 rotates out of alignment,
The shaft 3 fixed to the second arm also rotates by the same amount. The chain 4 wound around the shaft therefore pulls the single-edged spring 5 upwards. What happened to the end of spring 5? Since the spring 5 is supported by the subassembly 7 so as not to rise against the tension of the spring 1l16, the spring 5 ends up elongating by an amount proportional to the rotation angle of the shaft 3. FIG. 2 shows examples of changes in A to J in the example of FIG. 1, the rotation angle, the change in moment due to its own weight, and the change in moment due to the restoring force of the spring.

The curve 8 represents the change in moment due to the arm's own weight, and the straight line 9 represents the change in moment 1- due to the restoring force 1' of the spring. From FIG. 2, the sum of the curve 8 and the straight line 9 is not necessarily 0. In other words, it is impossible to achieve perfect balance in the example shown in FIG.

+-i aspect of invention The present invention overcomes the above drawbacks.

Composition of the Invention The present invention comprises two arms that are mutually rotatably supported and constitute a joint, and an elastic body that has a restoring force in a direction that cancels out the moment 1 around the axis due to the own weight of one of the arms. A gravitational Balanne device equipped with a cam mechanism that adjusts the restoring force of the elastic body can perfectly balance the arm's own weight.

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be described below with reference to FIGS. 3 to 6. In FIG. 3, the first arm 16 and the second arm 11 are connected by a shaft 12, and the second arm 11 and the shaft 1
2 is fixed. A chain 13 is attached to the shaft 12, and springs 14 are attached to both sides of the chain 13. Furthermore, a weight 15 is attached to the end of the spring 14. The plate cam 16, which is still fixed to the shaft 12, forms a cam mechanism with a cam follower 17, forcing the link 18 to reciprocate.

The link 18 is limited to linear reciprocating motion by a subassembly 19 fixed to the first arm 10.

Next, the bribery operation of the above configuration will be explained. Second arm 11
Suppose that it rotates clockwise. The shaft 12 fixed to the second arm 11 rotates by the same amount as the second arm 11, and through the chain 13 the spring 14 lifts upwards by an amount proportional to the angle of rotation.

Meanwhile, the plate cam 16 fixed to the shaft 12 also rotates, pushing down the link 18 through the cam follower 17. The link 18 further pushes down the weight 15 and pushes the spring downward. Therefore, the extension of the spring 14 is the sum of the amount proportional to the rotation angle and the amount pushed down by the cam, and the restoring force is also a force proportional to the rotation angle and a force generated by pushing down by the cam. It becomes a harmony with By determining the rotation angle and the displacement to be pushed down by the cam in advance, it becomes possible to determine the shape of the cam and balance the dead weight of the second arm and the restoring force of the spring in any state. For example, the 11th Il! Let L be the distance from the center of gravity to the J rotation center, the weight of the second arm -(tl be W, the half of the shaft 12 be r, the bullet 1j coefficient of the spring 14 be k, and the rotation sound θ of the second arm.

The point θ-0 is the point at which the second arm is in position. At this time, the condition for the moments to be balanced is W L 5llllθ=r(
K,! r+krθ) Therefore, the shape of the cam, the shape of the cam follower, etc. should be adjusted to satisfy this.

FIG. 4 shows the relationship between the rotation angle of the second arm 11 and the torque applied to the shaft 12. The curve 20 is due to the dead weight of the second arm), and the straight line 21 is the torque of the restoring force of the spring 14, which is proportional to the rotation angle. If the torque due to the restoring force of the spring 14 becomes like the curve 22, it will be balanced at any rotation angle of the second arm. The torque required to make the torque due to one summer force of the spring 14 become the curve 22 is shown as the curve 23 in FIG. 5. In other words, the cam mechanism causes a deflection of 1 for 230 minutes of the curve in Figure 6.
It is a good idea to adjust the stretch in step 4.

Next, a second embodiment is shown in FIG. The first arm 241 and the second arm 25 rotate relative to each other about an axis 26. axis 2
A chain 27 is wound around the chain 27, and the rotation is transmitted to the cam 29 through the shaft 28, and there is a handle 3O in the middle, through which the spring 31 is pushed up. The handle 30 and the spring 31 are connected to a guide 32 that limits translation, and the guide 32 is fixed to the first arm 24. On the other hand, the shaft 2 and the cam 29 that can be rotated by the chain 2γ are 1, and the cam follower 3 has a cam structure with the cam 29.
3 is given linear motion interlocking. Cam Follower 33 is Bukai 34
The spring 31 is connected to the spring 31 to apply a displacement. That is, the spring 31 receives a displacement proportional to the rotation of the second arm from the handle 3◯, and receives a displacement adjusted by the cam from the part 34. The restoring force due to these displacements passes through the handle 301f,
The torque is transmitted to the chain 2Y and balances with the second arm's own weight.

In the second example, compared to the first example, the chain 27 is made longer, so that the balance device can be moved to a position where the joints are far from each other (-1).

Effects of the Invention As described above, by adjusting the restoring force of the spring using the cam mechanism, it is possible to construct a joint that perfectly balances the arm's own weight. The above method occupies a small space and can be balanced at any joint angle, so it has a great practical effect on joint structures that are affected by gravity.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a conventional balance device, Figure 2 is a diagram showing the relationship between the joint angle at the joint part and the torque due to the arm's own weight, and the relationship between the joint angle and the torque due to the restoring force of the spring. Fig. 3 is an explanatory diagram showing the joint in the first embodiment of the present invention, Fig. 4 is a diagram showing the relationship between the joint angle and torque in the joint, and Fig. 5 is an explanatory diagram showing the relationship between the joint angle and torque in the joint. FIG. 6 is an explanatory diagram showing the joint f' (i+ part) in the second embodiment of the present invention. Two divisions, 1
2 Axis, 13... - cord-like body, 14-... elastic body,
16...Cam, 1...Cam follower, 18-
...Mu... link, 24, 26... two members constituting the joint, 26... shaft, 27... funicular body,
31...Elastic body, 29...Cam. 33-...cam follower, 34...link. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 6

Claims (2)

[Claims] (1) Two members that are rotatably supported by each other and constitute a joint, a shaft that supports the members, and a restoring force in the direction that cancels the moment around the shaft due to the weight of one of the members. an elastic body having an elastic body, an elementary body that transmits the amount of rotation of the shaft to the elastic body, and a cam that rotates around the shaft;
A balance device for an industrial robot, comprising a cam follower that follows the cam, and a link that is connected to the cam follower, transmits reciprocating motion to the elastic body, and adjusts the restoring force of the elastic body. (2) The central axis of rotation of the cam does not coincide with the axis, and there is a foot on one of the parts constituting the joint, and the central axis of rotation of the cam and the axis supporting the members constituting the joint are connected. Claim 1, wherein the elastic body has a base body that synchronizes rotation and a handle attached to the base body, and the amount of rotation of the shaft is transmitted to the elastic body via the handle. industrial robot balance device.