JPH0742742A - Linking device - Google Patents

Abstract

PURPOSE:To make any flection of linkage mechanism so as to be restrainable as well as to capacitate its hermetically sealed structure to be simplified by checking any dusting out of a rolling bearing in an articulated part. CONSTITUTION:In a linkage mechanism in which two beltlike links 1 and 2 are connected free of rocking motion via two rolling bearings 3 and 4, these bearings 3, 4 are made into an angular full type ball bearing each, and both rolling elements 3c and 4c consisting of this type ball are formed into ceramics using silicon nitride as the main ingredient and used by means of nonlubricant. With this constitution, withstand load capacity in this rolling bearing is especially increased as compared with the conventional deep-groove type ball bearing heretofore in use. In addition, since (retainer) a sliding object of the rolling element is omitted in addition to being used in a nonlubricant way, a quantity of dusting sharply becomes lessened as compared with a case using the conventional solid lubricant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a link mechanism, and more particularly to improvement of a joint portion of at least two links.

[0002]

2. Description of the Related Art As a conventional link mechanism, as shown in, for example, Japanese Patent Application Laid-Open No. 5-60143, one rolling bearing is internally fitted and mounted in each through hole provided in each one end of two links. There is known a structure in which both end portions of one shaft are internally fitted and attached to the inner peripheral portions of these two rolling bearings.

As the rolling bearing here, a deep groove type ball bearing using a general cage is used, which is usually grease lubricated, but is installed inside the chamber of a semiconductor manufacturing apparatus such as a sputtering apparatus. Since the link mechanism for semiconductor wafer transfer is in a harsh environment such as vacuum and high temperature, it is lubricated using a solid lubricant.

[0004]

In the case where the above-mentioned link mechanism is horizontally supported in a cantilever state, the axial load and moment load acting on the rolling bearing of the joint portion of the link become large, so that the link The bending of the mechanism on the free end side becomes large, and the positioning accuracy on the free end side may decrease. On the other hand, the weight of each link is reduced, but there is a limit to that. Also,
Although it can be dealt with by giving a large preload to the rolling bearing and setting the internal clearance to a minimum, in this case,
The rolling resistance of the rolling bearing increases and the smoothness of the movement decreases, and the wear of the rolling elements and the raceways of the bearing rings becomes severe and the life of the rolling bearing becomes significantly shortened. Use a cross roller type as the rolling bearing to increase the load,
Although the one that copes with the moment load resistance has been put into practical use, the cross roller type is more difficult to downsize than the ball bearing,
In addition, the rotation torque is large, and slippage may occur when the preload is applied. Since the internal space is small and the amount of lubricant is limited, the lubrication performance is poor.

Further, when the rolling bearings of the joints are lubricated with a solid lubricant, dust is often generated due to wear and peeling, so that the bearings are used particularly in a clean space such as the semiconductor manufacturing apparatus described above. In that case, it is necessary to devise a rigorous seal structure.

In view of such circumstances, it is an object of the present invention to suppress the flexure of the link mechanism and to suppress dust generation from the rolling bearings of the joints to simplify the sealing structure. And

[0007]

SUMMARY OF THE INVENTION The present invention is a link mechanism using a rolling bearing in a joint portion for swingably linking at least two links, wherein the rolling bearing is a full ball bearing, and at least the rolling bearing is used. The moving balls are made of ceramics and are used without lubrication.

[0008]

In the above structure, since the rolling bearing of the joint portion is the full ball bearing and the balls are made of ceramics, the load bearing capacity of the rolling bearing is remarkably improved as compared with the conventional general deep groove type ball bearing.

Further, this rolling bearing is made of ceramics so that it can be used without lubrication, and the rolling bearing is used as a full ball bearing without using a cage to reduce the sliding objects of the rolling elements. Therefore, the amount of dust generated is suppressed to be smaller than that in the case of using the conventional solid lubricant.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on the embodiments shown in FIGS. FIG. 1 shows a vertical sectional side view of a link mechanism according to a first embodiment of the present invention, and FIG. 2 shows an exploded perspective view of the mechanism. The link mechanism shown in the figure has two belt-shaped links 1 and 2, respectively. Each one end side of is connected swingably through rolling bearings 3 and 4, and the structure of the joint will be described in detail below.

One end of the first link 1 is formed in a U shape, and a pair of tongues 1a, 1b facing each other are provided with coaxial through holes 1c, 1d. Further, one end of the second link 2 has a tongue piece 1 at the U-shaped end of the first link 1.
It is formed in a tongue shape having a size to be inserted between a and 1b, and has a through hole 2a having a smaller diameter than the through holes 1c and 1d of the first link 1.

Both ends of the shaft 5 in the axial direction are rotatably supported in the through holes 1c and 1d of the first link 1 via one rolling bearing 3 and 4, and an axially intermediate portion of the shaft 5 is provided. Second
It is fitted and fixed in the through hole 2 a of the link 2.

The inner rings 3a, 4a of the rolling bearings 3, 4 are fixedly attached to the shaft 5 by the step portion of the shaft 5 and the retaining rings 6, 6, and the outer rings 3b, 4b penetrate the first link 1. The retaining rings 7, 7 on the inner opening side of the holes 1c, 1d prevent the holes 1c, 1d from coming out of the inner opening. A wave washer 8 is interposed between the outer ring 3 a of the one rolling bearing 3 and the retaining ring 7 of the one rolling bearing 3, and a preload is applied to the two rolling bearings 3 and 4 by the wave washer 8. It is supposed to do. Also, the tongue piece 1 of the first link 1
Seal plates 9 and 9 are attached to the outer surfaces of a and 1b so as to close the outer openings of the through holes 1c and 1d.

The above rolling bearings 3 and 4 are angular type full ball bearings having a contact angle of 30 degrees and are back-to-back,
Inner / outer rings 3a, 4a, 3b, 4b are SUS440C
The rolling elements 3c and 4c made of martensitic stainless steel, balls, etc. are used without lubrication as ceramics mainly composed of silicon nitride. The preload of the wave washer 8 on the rolling bearings 3 and 4 is set to 2 Kgf. The rolling bearings 3 and 4 may be replaced by deep groove type ball bearings.

The first and second links 2 and 3 are made of aluminum alloy, and the shaft 5 is made of austenitic stainless steel such as SUS304. If such a material is selected, the difference in linear expansion coefficient between the first and second links 2 and 3 and the rolling bearings 3 and 4 becomes large, so that the preload on the rolling bearings 3 and 4 may change depending on the ambient temperature. Although conceivable, in the present embodiment, the preload on the rolling bearings 3 and 4 can be kept substantially constant by the wave washer 8 in response to the state change accompanying the temperature change.

As described above, if the structure of the rolling bearings 3 and 4 used for the joint portion of the link mechanism is specified, the load bearing capacity is remarkably improved as compared with a general deep groove type ball bearing.
Specifically, a displacement of the bearing in the axial direction was measured under a condition that an axial load of 5.0 kg was applied to a deep groove type ball bearing of JIS model number 6000.
On the other hand, the displacement amount was 0.0021 mm under the same conditions in the angular contact ball bearing of the present embodiment having the same dimensions as described above, which was about 0/3 mm of that of the comparative product. It was also confirmed that it became smaller. In other words, it can be said that the load bearing capacity of this example is about three times as high as that of the conventional example. Moreover, in the rolling bearings 3 and 4 of this embodiment, the rolling elements 3c and 4c are used as ceramics without lubrication, and since the cage is not used as the full ball bearing, compared with the case where the conventional solid lubricant is used. The amount of dust generated is significantly reduced. Therefore, the sealing structure of the rolling bearings 3 and 4 does not need to be strict as in the conventional case, and the equipment cost related to the sealing structure can be reduced.

3 and 4 show a second embodiment of the present invention. FIG. 3 is a vertical sectional side view of the link mechanism, and FIG. 4 is an exploded perspective view of the same mechanism. In the present embodiment, the first and second links 1 and 2 are made of thin plate materials, and the shaft 5 is fixed to one end of the first link 1, and the shaft 5 is provided in the through hole 2a of the second link 2 in a double row. It is supported via the rolling bearing 3. The rolling bearing 3 here is a deep groove type ball bearing, and a preload is applied by the wave washer 8. In addition, the same reference numerals as those in FIG. 1 indicate the same parts or corresponding parts.

The present invention is not limited to the above embodiment. For example, the rolling bearings 3 and 4 may be sealed by using other general seals.

[0019]

As described above, according to the present invention, since the load bearing capacity of the rolling bearing of the joint portion is remarkably improved as compared with the conventional general deep groove type ball bearing, the flexure of the link mechanism is caused. Can be suppressed to a small value, and movement can be properly managed.
Moreover, since this rolling bearing is configured so that it can be used without lubrication and the sliding object (retainer) of the rolling elements is reduced, the amount of dust generated is significantly larger than when using conventional solid lubricants. It is possible to contribute to the reduction of the equipment cost, such as the reduction of the total cost and the simplification of the sealing structure.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a first embodiment of a link mechanism of the present invention.

FIG. 2 is an exploded perspective view of the link mechanism of the first embodiment.

FIG. 3 is a vertical sectional side view of a second embodiment of the link mechanism of the present invention.

FIG. 4 is an exploded perspective view of a link mechanism according to a second embodiment.

[Explanation of symbols]

 1, 2 links 3,4 rolling bearings 3c, 4c rolling elements

Claims (1)

[Claims] 1. A link mechanism using a rolling bearing at a joint portion for swingably connecting at least two links, wherein the rolling bearing is a full ball bearing, and at least balls as rolling elements are ceramics. The link mechanism is characterized in that it is formed of, and is used without lubrication.