JPS58181596A - Wrist mechanism of 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 The present invention relates to a wrist mechanism for an industrial robot having one rotation axis.

Generally, industrial robots are required to have high positioning accuracy. Among these, the wrist part is required to be small and highly rigid, as it is close to the part where work is actually performed.

In the conventional example shown in Figure 4, the number seven leaves was 14 days.

In order to ensure the support of the first rotating body 11 of the wrist bending shaft, the nut 50 is tightened and the first bearing 2 and the second bearing 2 are tightened.
Apply preload to the first bearing 27. The internal gap of the second bearing 28 is eliminated to increase rigidity.

However, since this preload is also applied to the third bearing 49 at the same time, the strength and life of the third bearing 49 become a problem.

Since the wrist is required to be small, the third bearing 49
is the first bearing 27. It has to be made smaller than the second bearing 28. Then, the load capacity of the 1s3 bearing 49 is naturally the first
Bearing 27. It becomes smaller than the second bearing 28. Therefore, since a sufficient preload cannot be applied to the first bearing 27° and the second bearing 28, the rigidity cannot be sufficiently increased, and the first rotating body 11 causes lateral wobbling in response to external force. External forces include, for example, those caused by the inertia of a jig or workpiece attached to the tip of the wrist, those caused by the tension of the chain 18, and those caused by the first bevel gear 34 and #! If the meshing with the two bevel gears 37 is too strong, there are cases where this occurs on every tooth as the meshing progresses. If lateral vibration occurs in the first rotating body 11, the actual working point will also be lowered, resulting in a serious problem in terms of accuracy.

The purpose of the present invention is to provide sufficient preload to the first bearing 27 and the second bearing 28 that support the first rotating body 11, without causing disadvantages in terms of strength and life, and to increase the support rigidity of the first rotating body 11. The object of the present invention is to provide a mechanism that can increase the height sufficiently.

In the conventional example shown in FIG. 4, in order to ensure the support of the first rotating body 11, the first bearing 27. Although a preload is applied to the second bearing 28, this preload also acts as a thrust load, so the strength and life of the small third bearing 49 on the inside becomes a problem, and a sufficient preload cannot be applied. Therefore, a thrust bearing of the same size but with a much larger thrust load capacity is added, and the third bearing 49 is made to bear only the radial load. Also, K is selected so that the magnitude of preload can be easily controlled.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

1 is the base% 2 is the rotating table that rotates on the pace 1,
3 is an arm that swings around a point 4 on the rotating table 2; 5 is an arm that swings around a point 6 on the arm 3; 7 is a drive means for swinging the arm 3; 8 is a lever 9 ．．
This is a driving means for swinging the arm 5 via the arm 10.

The ``th'' rotating body 1F is supported by the arm 5 via the ``th'' □ bearing 27 so as to be rotatable about the axis 12. The first rotating body 11 is configured to be driven by the first driving means 13 via sprockets 14, 15, 16 and chains 17, 18. The sprocket 16#i is fixed to the first rotating body 11.

A second rotating body 19 is provided on the axis 12 and rotatably supported by the arm 5. this#! The two-turning body 19 is.

By the second driving means 20, the sprockets 21, 22.
25 and a chain 24.25. The sprocket 23 is also integrated with the post 26,
The outer peripheral surface of the post 26 is rotatably supported by the arm 5 via the second shaft 28. At the same time, the second rotating body 19 is rotatably supported by the first rotating body 11 via the needle bearing 56 and the thrust bearing 48, and
On the outside of the step, the diameter is made one step smaller, a contact plate 57 is brought into contact with the stepped portion, and the nut 50 is tightened. Abutment plate 57 and thrust bearing 4
A compression spring 58 is provided between the two. The first bevel gear 34 is f
a2 Provided to prevent rotation relative to the rotating body 19. In other words,
A sliding key 35 is provided between the inner circumferential surface of the post 26 and the outer circumferential surface of the post portion of the first bevel gear 34. A compression spring 36 is provided between the first bevel gear 34 and the sprocket 23.

The first rotating body 11 is provided with a through hole 29 extending in a direction perpendicular to the rotation axis 12 of the first rotating body 11. This through hole 29 is provided with a step 30 whose diameter is larger on the side farther from the axis 12.

The third rotating body 51 is rotatably supported by the first rotating body 11 through the fourth bearing 52 and the fifth bearing 33 in the through hole 29 . The second bevel gear 37 is fixed to the third rotating body 3F, and this is j
11 meshes with bevel gear 34.

A ring 39 is provided at an opening 38 of the through hole 29 that is far from the second rotating body 19. This ring 39 has a female thread 40, and the first rotating body 11 has a male thread 41 that screws into this female thread 40.

The fourth bearing 32 is attached to the outer race 42 of the ring 3.
9 and the stepped portion 30.

Further, the inner race 44 is provided so as to be able to slide on the third rotating body 31.

The fifth bearing 33 is provided between the fourth bearing 32 and the second bevel gear 37 and relative to the third rotating body 31 .

The outer diameter of the fifth bearing 33 is smaller than the maximum outer diameter of the fourth bearing 32 and larger than the maximum outer diameter of the second bevel gear 37.

A compression spring 45 is provided between the inner race 44 of the fourth bearing 32 and the inner race 43 of the fifth bearing 33.

Now, in the structure configured as above 1, when the first drive means 13 is operated, the sprocket 14, the chain 17
．． Sprocket 15. Chain 18° Sprocket 16
After that, the first rotating body 11 rotates about the axis 12. Therefore, the direction of the fifth rotating body 31 changes.

Moreover, when the second driving means 20 is operated, sedge is produced. Rocket 21% chain 24. sprocket) 22, handmade 25
．． The second rotating body 19 is connected to the shaft l112 via the sprocket) 23.
Rotates around the center. This rotation is caused by the first bevel gear 34. It is transmitted to the third rotating body 31 via the second bevel gear 37, and the third rotating body 31 rotates around the axis of the through hole 29.

Therefore, according to the present invention, since the second rotating body 19 is supported with respect to the first rotating body 11 by the thrust bearing 48 and the needle bearing 56, the first bearing 27. Second bearing 2
The thrust load capacity of the first bearing 27.8 and the thrust bearing 48 can be made equal to that of the first bearing 27.8. By applying sufficient preload to the second bearing 28, it is possible to increase the supporting rigidity of the first rotating body 11. Furthermore, since the magnitude of this preload depends on the compression spring 58, it can be controlled by tightening the nut 50 until the contact plate 57 comes into contact with the stepped portion of the shaft. in this case,
The range of variation in the magnitude of the preload is determined only by the range of variation in manufacturing accuracy of parts such as the length of the shaft of the second rotating body 19 and the distance between the steps 54 and 55 of the arm 5. management becomes reliable and easy.

(In the present invention, the described preload means that the first bearing 27 and the second bearing 28 are applied to the stepped portion 54 of the arm 5 during assembly.
55) According to the present invention, the first bearing 27 and the second bearing 28 that support the first rotating body 11 can be Since sufficient preload can be applied, there is an effect of increasing the support rigidity of the first rotating body 11.

[Brief explanation of drawings]

1 and 2 are front and side views showing an embodiment of a robot equipped with the wrist mechanism of the present invention, FIG. 3 is an enlarged view showing a main part of the embodiment cut away, and FIG. 4 is a conventional example. FIG. 2 is an enlarged view showing a main part cut away. 5ij A-4, 1114$1 Rotating body, 03 is first driving means, 19 second rotating body, 20 is second driving means. 27 is the ta1 bearing, 2B is the second bearing, 31 is the third rotating body, 34 is the first bevel @1g, 57 is the second bevel gear, 48 is the thrust bearing, 50 nuts, 56 needle bearings, 57 is the The plate 58 is a compression spring. -57: Figure 2 Figure 1

Claims (1)

[Claims] a first rotating body rotatably supported by an arm via a first bearing; a first driving means for rotationally driving the first rotating body;
The first rotating body is provided on the rotation wheel line of the first rotating body, is rotatably supported by the arm via a second bearing, and is rotatably supported by the arm via a second bearing.
a second rotating body rotatably supported by the first rotating body via a radial bearing and a thrust bearing provided on the rotating body; and a second driving means for rotationally driving the second rotating body; a contact plate that generates a thrist preload between the moving body and the thrist bearing; a through hole provided in the first rotating body and extending in a direction perpendicular to the rotational axis of the first rotating body; A sixth rotating body rotatably supported and the second rotating body are provided inside.
It consists of a bevel gear that is prevented from rotating with respect to the rotating body, and a second bevel gear that is fixed to the third rotating body and meshes with the first bevel gear. '' A wrist of an industrial robot, characterized in that sufficient thrust preload is applied to a first bearing that supports a rotating body and a second bearing that supports a second rotating body, thereby increasing the supporting rigidity of the first rotating body. mechanism.