JP2000220650A - Bearing case and bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily assemble a rolling bearing to the bearing mounting surface of a bearing case without damaging it by covering the bearing mounting surface to which the rolling bearing is fitted with a protecting film. SOLUTION: When the bearing case 51 of a first joint part 5 is formed of a relatively soft material such as aluminum alloy, a trouble (damage, assembling failure) is easy to occur when rolling bearings 53, 54 are assembled into the bearing case 51. Therefore, in order to protect the bearing mounting surface of the bearing case 51 and enhance the slidability, a protecting film 10 such as hard film or solid lubricating film is applied to the bearing mounting surface. Since the application of the protecting film makes the rolling bearing easily slidable in the assembly of the rolling bearings, the bearing mounting surface is never damaged, and the inclination of the axis of the rolling bearing can be corrected in the assembling process even if the axes of the both are slightly shifted in the assembly of the rolling bearing to the bearing mounting surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a bearing device. This bearing device is used, for example, for a joint of a robot arm.

[0002]

2. Description of the Related Art Conventionally, a bearing device is used for a joint of a robot arm. This bearing device is configured to include a bearing case, a shaft inserted through the inner periphery of the bearing case, and a rolling bearing that allows the bearing case and the shaft to rotate relative to each other.

[0003] Rolling bearings are incorporated into a bearing case by a "stop fit" in which interference is set to "0".
Alternatively, a fitting form such as “tight fitting” with a negative interference is used.

In recent years, in order to reduce the weight, the bearing case is formed of an aluminum alloy. However, the components of the rolling bearing vary depending on the application, but are formed of a steel material such as bearing steel or stainless steel.

[0005]

When a rolling bearing made of a relatively hard material is mounted on a bearing case made of a relatively soft material as described above, the mounting of the bearing case on the bearing case is performed during the mounting process. The surface is easily damaged (scratch, galling, etc.).

Further, in the process of assembling, if the axis of the outer ring of the rolling bearing is slightly inclined at least with respect to the axis of the bearing mounting surface of the bearing case, the bearing case may be attached to the bearing mounting surface of the bearing case. On the other hand, the edge of the outer ring of the rolling bearing is apt to bite, and in extreme cases, it may not be able to be assembled to the specified position.

It is conceivable to incorporate a rolling bearing by applying oil to the bearing mounting surface or by heating and expanding the bearing case. However, these treatments are not only troublesome. However, such an effect cannot be obtained that the above-mentioned problem can be solved.

In view of such circumstances, an object of the present invention is to make it possible to easily incorporate a rolling bearing into a bearing mounting surface of a bearing case without damaging the rolling bearing.

[0009]

According to a first aspect of the present invention, a bearing case is made of an aluminum-based soft metal, and a bearing mounting surface on which a rolling bearing is internally fitted is coated with a protective film.

In a bearing case according to a second aspect of the present invention, the protective film of the first aspect is a hard film.

In the bearing case according to a third aspect of the present invention, the hard film of the second aspect is made of either nickel or a nickel-based metal.

According to a fourth aspect of the present invention, in the bearing case, the protective film of the first aspect is a solid lubricating film.

According to a fifth aspect of the present invention, in the bearing case, the solid lubricating film of the fourth aspect is made of a fluorine-based synthetic resin, gold, silver,
Any of soft metals such as copper and lead, graphite, molybdenum disulfide and the like.

According to a sixth aspect of the present invention, there is provided a bearing device according to any one of the first to fifth aspects, a shaft body inserted into the inner periphery of the bearing case, and a relative rotation between the bearing case and the shaft body. And rolling bearings to enable this.

As described above, if the protective film is provided on the bearing mounting surface of the bearing case, the rolling bearing does not need to come into direct contact with the bearing case when the rolling bearing is incorporated.

Regardless of whether the former protective film is a hard film or a solid lubricating film, the rolling bearing becomes slippery when the rolling bearing is incorporated, so that the bearing mounting surface of the bearing case is not damaged. When the rolling bearing is mounted on the bearing mounting surface of the bearing case, even if the axes of the two are slightly misaligned, the inclination of the axis of the rolling bearing is corrected during the mounting process.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on embodiments shown in the drawings.

FIGS. 1 to 4 show an embodiment of the present invention. In this embodiment, a robot arm will be described as an example of an object to which the bearing device of the present invention is used.

First, the overall configuration of the robot arm will be described with reference to FIGS. FIG. 1 is a perspective view showing the entire configuration of the robot arm, and FIG. 2 is an exploded perspective view of a main part of the robot arm.

The illustrated robot arm 1 includes two sets of arms 2 and 3 and a transfer table 4 attached to the free ends of the arms 2 and 3. (Not shown) is used to carry the sheet linearly.

Each of the arms 2 and 3 has one end of each of two band-shaped links 2a, 2b, 3a and 3b swingably connected via first joints 5 and 5, respectively. This arm 2,
The transfer table 4 is attached to the end of each of the first links 2a, 3a via second joints 6, 6. Also,
The end positions of the second links 2b and 3b of the arms 2 and 3 are as follows.
They are arranged so as to be at the same swing fulcrum and are attached to a drive motor (not shown). In other words, this arm 2,
3 is cantilevered in a horizontal posture with respect to the drive motor.

The operation of the robot arm 1 having such a configuration is as follows. Each of the two links 2a, 2b, 3a, 3b of the pair of arms 2, 3 is driven symmetrically by a drive motor as shown by an arrow A in FIG. If the arm is bent or extended, the total length of the arms 2 and 3 can be changed.
In response, the transport table 4 is moved as shown by the arrow B in FIG.
It will be moved back and forth in the front-back direction.

The first and second joints 5, 6 of the robot arm 1 described above correspond to the bearing device of the present invention. The first and second joints 5 and 6 will be described in detail with reference to FIGS. FIG. 3 is a side view in which the left half of the first joint of the robot arm is sectioned, and FIG. 4 is a side view in which the left half of the second joint of the robot arm is cross section.

The first and second joints 5 and 6 are both mainly bearing cases 51 and 61, shafts 52 and 62 inserted through the inner circumferences of the bearing cases 51 and 61, and the bearing cases 51 and 61.
Although it is composed of two rolling bearings 53, 54, 63 and 64 that support the shaft 61 and the shaft bodies 52 and 62 so as to be able to rotate relative to each other, these components are different from each other in small points. This will be described below.

(First Joint 5) The bearing case 51 is formed in a U-shape, and its two opposing tongues 51
Coaxial through-holes 51d and 51e are formed in a and 51b. The shaft body 52 is inserted across these through holes 51d, 51e, and these two tongue pieces 51a, 51
The second links 2b and 3b of the arms 2 and 3 are attached by bolts 8 to the outer surface of the connecting portion that integrates 1b.

The shaft body 52 is formed in a hollow shape, and has a flange 52a protruding radially outward at one shaft end, and a nut 55 screwed around the other shaft end. A screw portion is formed. A link support member 56 is externally fitted and fixed to an axially intermediate portion of the shaft body 52, and the first links 2 a and 3 a of the arms 2 and 3 are attached to the link support member 56 by bolts 9.

The two rolling bearings 53 and 54 are, for example, angular contact ball bearings, and each of the through holes 51 d and 51 e of the two tongue pieces 51 a and 51 b of the bearing case 51 and the outer peripheral surface of the shaft 52 It is interposed between the regions near both ends in the direction.

The tongue piece 51 of the bearing case 51
Sealing lids 57, 57 for closing the outer openings of the through holes 51d, 51e, respectively, are attached to the outer end surfaces of the shaft members 52a, 51b. Seal rings 58, 58 are externally fitted and fixed. These sealing lid 57 and sealing ring 5
8, the rolling bearings 53 and 54 are sealed from the outside.

The through hole 51 of the bearing case 51
Retaining rings 59, 59 are fixedly mounted on the inner periphery of the d and 51e, and one of the retaining rings 59 and one of the rolling bearings 5 are provided.
A wave washer 60 is interposed between the outer ring 3 and the inner end face of the outer ring. The wave washer 60 is provided between the two rolling bearings 5.
3 and 54 are compressed by being sandwiched between the flange 52 a of the shaft body 52 and the nut 55. The compression restoring force of the wave washer 60 is applied as a preload to the two rolling bearings 53 and 54, whereby the bearing case 51
The play between the shaft member 52 and the shaft member 52 is eliminated.

(Second Joint 6) The bearing case 61 is formed in a cylindrical shape, and an outward flange 61a protruding radially outward is provided at an axially intermediate portion of the outer peripheral surface thereof.
An inward flange 61b is provided at the axial center of the inner peripheral surface to protrude radially inward. The first link 2 of the arms 2 and 3 with respect to the outward flange 61a.
a, 3a are attached by bolts 10.

The shaft body 62 is formed in a hollow shape. A flange portion 62a is provided at one shaft end so as to protrude radially outward, and a nut 65 is screwed around the other shaft end. A screw portion is formed. The transfer table 4 is attached to the outer end surface of the flange 62a by bolts (symbols omitted).

The two rolling bearings 63 and 64 are, for example, angular contact ball bearings, and are formed on the inner peripheral surface of the bearing case 61 on both sides separated by inward flanges 61b and on the outer peripheral surface of the shaft body 62 in the axial direction. It is interposed between the areas near both ends.

A seal ring 66 is provided between the nut 65 of the shaft 62 and one of the rolling bearings 63, and the seal ring 66 and the flange 6 of the shaft 62 are provided.
2a seals the rolling bearings 62 and 63 from the outside.

A wave washer 67 is interposed between one end of the inward flange 61b of the bearing case 61 and the inner end of the outer ring of one of the rolling bearings 63. The wave washer 67 is compressed by sandwiching the two rolling bearings 63 and 64 between the flange 62 a of the shaft body 62 and the nut 65. The compression restoring force of the wave washer 67 is applied as a preload to the two rolling bearings 63 and 64, whereby the bearing case 61 and the shaft body 62 are provided.
The gap between them is eliminated.

Next, the features of the present invention will be described.

In the robot arm 1 as described above, the links 2a, 2b,
3a, 3b and the bearing case 5 of the first and second joints 2, 3
The ring support member 56 is formed of, for example, an aluminum alloy. The shafts 52, 62, the nuts 55, 65, and the retaining ring 59 of the first and second joints 5, 6 are formed of, for example, stainless steel such as JIS standard SUS304. Further, the rolling bearings 53, 54, 63, 64
Is formed of general bearing steel or various stainless steels. However, depending on the use environment of the robot arm, the rolling elements may be formed of silicon nitride ceramics.

When the bearing cases 51 and 61 of the first and second joints 5 and 6 are made of a relatively soft material such as an aluminum alloy, the rolling bearings 53 and 54 are formed with respect to the bearing cases 51 and 61. , 63, 64,
The defects (damage, improper installation, etc.) as described in the item of the conventional example are likely to occur.

Therefore, in this embodiment, in order to protect the bearing mounting surfaces of the bearing cases 51 and 61 and improve the slip, the protective film 10 such as a hard film or a solid lubricating film is provided on the bearing mounting surfaces. Coated.

As the above-mentioned hard film, nickel (Ni)
Alternatively, a nickel alloy (Ni-P, Ni-B) or the like can be used. The hardness is preferably set to, for example, Vickers hardness (Hv) of 500 or more. The film thickness is preferably controlled, for example, to 10 ± 2 μm.

On the other hand, as the solid lubricating film, fluorine-based synthetic resin (polytetrafluoroethylene: PTFE), gold,
Soft metals such as silver, copper and lead, graphite, molybdenum disulfide and the like can be mentioned. The friction coefficient is set to 0.1.
It is preferably set to 3 or less. The film thickness is preferably controlled, for example, to 2 to 6 μm.

The rolling bearings 53, 54, 63, 64 are incorporated into the bearing cases 51, 61 by a "tight fit" in which the interference is "0" or a "tight fit" in which the interference is negative. It is a fitting form.

If such a protective film 10 is formed,
The bearing mounting surfaces of the bearing cases 51, 61 are strengthened, and the rolling bearings 53, 54, 63, 64 do not directly contact the bearing mounting surfaces. In addition, since the slippage of the rolling bearings 53, 54, 63, 64 is improved when the rolling bearings 53, 54, 63, 64 are assembled, the mounting surfaces of the bearing cases 51, 61 are not damaged. Rolling bearing 5 against surface
When the three, 54, 63 and 64 are assembled, even if their axes are slightly shifted, the rolling bearings 53 and
The inclination of the axis center of 4, 63, 64 is corrected.
Therefore, the rolling bearings 53, 54, 63, 64 can be easily incorporated into the bearing mounting surfaces of the bearing cases 51, 61 without damaging them.

However, when the protective film 10 is a solid lubricating film, the load applied to the rolling bearings 53, 54, 63, 64 is preferably used as a light load.

It should be noted that the present invention is not limited to only the above embodiment, and various applications and modifications are conceivable.

(1) In the above embodiment, the first and second
The rolling bearings 53, 54, 63, 64 of the joints 5, 6
Deep groove ball bearings and various roller bearings can be used.

(2) In the above embodiment, when used in a vacuum or high temperature environment, the rolling elements of the rolling bearings 53, 54, 63, 64 of the first and second joints 5, 6 and the inner / outer rings. On the other hand, it is preferable to coat with a fluorine-based synthetic resin (polytetrafluoroethylene: PTFE), a soft metal such as gold, silver, copper, or lead, graphite, or molybdenum disulfide.

(3) In the above embodiment, the bearing case and the bearing device of the present invention are used for the robot arm, but can be used for other devices.

[0048]

According to the first to sixth aspects of the present invention, a protective film is provided on a bearing mounting surface of a bearing case made of a relatively soft material such as an aluminum alloy, so that when a rolling bearing is incorporated, the rolling bearing can be directly mounted. Contact can be avoided, and the rolling bearings become slippery, so that the bearing mounting surface of the bearing case can be prevented from being scratched, and when the rolling bearing is mounted on the bearing mounting surface of the bearing case, Even if the two axes are slightly displaced, the inclination of the axis of the rolling bearing is corrected during the assembly process.

As described above, according to the present invention, the rolling bearing is not damaged without damaging the bearing case without troublesome operations such as applying oil at the installation site or heating and expanding the bearing case. It can be easily incorporated, and contributes to the improvement of productivity.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a robot arm to which a bearing device of the present invention is used.

FIG. 2 is an exploded perspective view of a main part of the robot arm.

FIG. 3 is a side view of a cross section of a left half of a first joint of the robot arm.

FIG. 4 is a side view in which a left half of a second joint of the robot arm is sectioned;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot arm 2, 3 arm 5 First joint part of arm 51 Bearing case of first joint part 52 Shaft body of first joint part 53, 54 Rolling bearing of first joint part 6 Second joint part of arm 61 First Joint case bearing case 62 First joint part shaft body 63, 64 Rolling bearing of first joint part 10 Protective film coated on bearing case

Continuation of front page (72) Inventor Hiroshi Ono 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Koyo Seiko Co., Ltd. F term (reference) 3J017 AA01 CA01 DB07

Claims (6)

[Claims] 1. A bearing case made of an aluminum-based soft metal, wherein a bearing film on which a rolling bearing is internally fitted is coated with a protective film. 2. The bearing case according to claim 1, wherein said protective film is a hard film. 3. The bearing case according to claim 2, wherein said hard film is made of nickel or a nickel-based metal. 4. The bearing case according to claim 1, wherein said protective film comprises a solid lubricating film. 5. The bearing case according to claim 4, wherein the solid lubricating film is made of any one of a fluorine-based synthetic resin, a soft metal such as gold, silver, copper, and lead, graphite, and molybdenum disulfide. Features bearing case. 6. A bearing case according to any one of claims 1 to 5, a shaft body inserted through the inner periphery of the bearing case, and a rolling bearing capable of relatively rotating the bearing case and the shaft body. And a bearing device characterized by that.