JPS61182787A - Magnetic fluid sealing structure in 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 a magnetic fluid seal structure in a robot.
More specifically, the present invention relates to a magnetic fluid seal structure suitable for industrial robots used in clean rooms.

C. Conventional technology and problems] When an industrial robot is used in a clean room, dust, metal powder, and moisture may leak from inside the robot into the clean room.
It is necessary to maintain airtightness inside the robot to prevent particulates such as agent particles from being released. Recently, magnetic fluid seals have been used in industrial products as means for sealing rotating shafts. As shown in FIG. 3, a magnetic fluid seal generally includes a ring-shaped permanent magnet 1, and a pair of ring-shaped pole pieces 2 having an inner diameter smaller than that of the permanent magnet 1 are provided on both end surfaces of the permanent magnet 1.
is fixed. The pole piece 2 is fixed to a housing member for supporting the rotating shaft 3 via a bearing or the like, and a minute gap is formed between the inner periphery of the pole piece 2 and the outer periphery of the rotating shaft 3. A magnetic fluid 4 is supplied inside the permanent magnet 1 . The magnetic fluid 4 is held between the pole pieces 2 by magnetic force.

Since it is necessary to uniformly form a minute gap between the inner circumference of the pole piece 2 and the outer circumference of the shaft 3, it is necessary to position the pole piece 2 of the magnetic fluid seal with high centering accuracy with respect to the rotating shaft 3. There is. Generally, as shown in FIG.
A plurality of shims 5 are immediately inserted between the shims 5 to center the pole pieces 2, and in this state the pole pieces 2 are fixed to the housing member with an adhesive or the like, and then the shims 5 are removed.

When the rotary shaft 3 extends in the same direction from the seal portion toward the shaft end, centering of the magnetic fluid seal using such a shim is facilitated with the rotary shaft supported by the housing member. can be done. However, when this magnetic fluid seal is applied to an industrial robot, the rotating shaft often has an integral flange close to the outside of the seal portion. Therefore, it is extremely difficult to accurately center the magnetic fluid seal using the method described above.

[Means for solving problems]

In view of the above problems, the present invention provides a magnetic fluid seal structure for a robot that allows accurate and easy centering of the magnetic fluid seal with respect to a flanged rotating shaft.

That is, the present invention provides a housing, a holder that is formed to be removably attached to the housing and has a cylindrical bearing holding part inside, and a bearing that fits into the bearing holding part of the holder. a rotating shaft with a flange that is rotatably supported; and a magnetic fluid seal that is disposed between the bearing and the flange of the rotating shaft and seals between the inner periphery of the holder and the rotating shaft. and, before the rotating shaft is assembled, the magnetic fluid seal body is fixed to the holder in advance in a centered state using a jig that is centered with the bearing holding part of the holder as a reference plane. A magnetic fluid seal structure for a robot is provided.

[For production]

According to the above means according to the present invention, the magnetic fluid seal body is centered and fixed to the holder by a jig that is centered using the bearing holding portion of the holder as a reference plane. Thereafter, the flanged rotating shaft is held by the holder via a bearing that fits into the bearing holding portion of the holder. Therefore, the magnetic fluid seal and the rotating shaft can be accurately aligned using the bearing holding portion of the holder as a common reference plane.

Furthermore, alignment of the magnetic fluid seal body using a jig can be easily performed without any obstructions such as flanges.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to the wrist of an industrial robot. In this example,
The robot wrist has two rotary output shafts 11.12, and the ends of the output shafts 11.12 are each integrally provided with flanges 13° and 14 for attaching attachments such as a mechanical hand, a sensor, etc. There is.

The robot wrist includes a housing 15.

The holder 1 is inserted into the hole 16.17 provided in the housing 15.
8.19 are removably fitted to each other, and the holder 1
8.19 are each fixed to the housing 15 by screws 20.21. Hole 16.17 in housing 15
A seal ring 22 is placed between the inner surface of the holder 18°19
．． 23 are attached to each.

A cylindrical bearing holder 24,25 is provided inside each of the holders 18,19.

One output shaft 11 is connected to the bearing holding portion 24 of the holder 18.
It is rotatably supported with respect to the housing 15 by a bearing 26 that fits into the housing 15 and a bearing 27 that fits into the housing 15. The other output shaft 12 has two bearings 28 that fit into the bearing holding part 25 of the holder 19.
It is rotatably supported with respect to the housing 15 by.

The output shaft 11 is connected to a drive source (not shown).

The output shaft 12 extends in a direction perpendicular to the output shaft 11, and the output shaft 12 is connected to the output shaft 11 via a pair of bevel gears 29 and 30.

A magnetic fluid seal 31 is provided between the bearing 26 and the flange 13 of the output shaft 11 for sealing between the inner periphery of the boulder 18 and the outer periphery of the output shaft 11. The holder I8 is formed with four parts for holding the magnetic fluid sealing body 31. A magnetic fluid seal 32 is provided between the bearing 28 and the flange 14 of the output shaft 12 to seal between the inner circumference of the holder 19 and the outer circumference of the output shaft 12. A concave portion for holding the magnetic fluid seal body 32 is formed in the cap 33 that fits into the bear link holding portion 25 of the holder 19 . Cap 33 is screw 2
1 is fixed to the holder 19.

Each of the magnetic fluid seals 31 , 32 includes a ring-shaped permanent magnet 34 . A pair of ring-shaped pole pieces 35 having an inner diameter smaller than that of the permanent magnet 34 are fixed to both ends of the permanent magnet 34, respectively.

A magnetic fluid 36, which is known per se, is supplied inside the permanent magnet 34, and the magnetic fluid 36 moves the pole piece 3 by magnetic force.
It is held between 5 and 5. The inner diameter of the pole piece 35 is the output shaft 11.12
The inner circumference of the pole piece 35 of the magnetic fluid seal body 31.32 and the output shaft 11.12
A minute gap is formed between the outer periphery of each. Pole piece 35 of magnetic fluid seal 31.32 and output shaft 11.1
In order to avoid contact with 2, the magnetic fluid sealing body 31°3
2 with respect to the output shaft 11, 12, respectively.

Referring to FIG. 2, the magnetic fluid seal 31 is mounted on a jig 37.
It is centered and fixed to the holder 18 with adhesive or the like. The outer peripheral surface of the jig 37 includes a cylindrical first fitting surface 38 that fits into the bearing holding part 24 of the holder 18 and a cylindrical second fitting surface 39 that fits into the inner periphery of the magnetic fluid sealing body 31. The second fitting surface 39 has a smaller diameter than the first fitting surface 38. Since the jig 37 is centered with respect to the bearing holding part 24 of the holder 18, by fitting the magnetic fluid seal body 31 to the second fitting surface 39 of the jig 37, the bearing holding part 24 is aligned with the reference plane. The magnetic fluid seal body 31 can be positioned as follows.

After fixing the magnetic fluid seal 31 to the holder 18 in this way, when the output shaft 11 is supported by the holder 18 via the bearing 26 as shown in FIG. Therefore, the magnetic fluid seal body 31 is accurately centered with respect to the output shaft 11.

Although not shown, the other magnetic fluid seal 32 is also centered and fixed to the holder 19 using a jig in the same manner as the magnetic fluid seal 3I. ``As mentioned above, the magnetic fluid seals 31.32 are centered with respect to the holder 18.19 before the assembly of the flanged rotary output shaft 11.12, so that they are not affected by the flanges 13.14. Centering work can be performed easily and accurately.

In this embodiment, a shim 40 for adjusting the meshing accuracy of the bevel gears 29 and 30 is attached to the housing 1.
An appropriate number of boulders are inserted between the end face of the boulder 19 and the boulder 19. However, the inner surface of the hole 17 of the housing 15 and the boulder 19
Since the seal ring 23 is provided between the outer peripheral surface of the housing 15 and the holder I9, the sealing performance between the housing 15 and the holder I9 is not impaired.

Although one embodiment has been described above, the present invention is not limited to the embodiment described above, and various changes can be made to its constituent elements within the scope of the invention described in the claims. .

For example, a robot wrist to which the present invention is applied may have a single rotary output shaft, or the present invention may be applied to a sealed portion of another rotary shaft of the robot.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to accurately align the magnetic fluid seal and the flanged rotating shaft using the bearing holding portion of the holder as a common reference plane. It is possible to provide a magnetic fluid seal structure for a robot that can easily perform 6-joint operation without causing any obstruction to the flange of the shaft.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a magnetic fluid seal structure of a robot showing an embodiment of the present invention applied to the wrist of an industrial robot. FIG. 2 is a sectional view of a magnetic fluid seal structure for a robot shown in FIG. FIG. 3 is a cross-sectional view showing a state in which centering is performed using a jig, and FIG. 3 is a partially cutaway front view showing a conventional method for centering a magnetic fluid seal. 11.12... Rotation output shaft, 13.14... Flange, 15... Housing, 1
8.19... Holder, 22.23... Seal ring, 24.25... Bearing holding part, 26.28... Bearing, 31.32... Magnetic fluid sealing body, 34... Permanent magnet, 35... Pole piece, 36... Magnetic fluid, 37... Jig, 38... First fitting surface, 39...
...Second mating surface.

Claims (1)

[Scope of Claims] 1. A housing, a holder that is formed to be removably attached to the housing and has a cylindrical bearing holding part inside, and a bearing that fits into the bearing holding part of the holder. a flanged rotating shaft rotatably supported on a holder; and a magnetic fluid seal disposed between the bearing and the flange of the rotating shaft to seal between the inner periphery of the holder and the outer periphery of the rotating shaft. and the magnetic fluid sealing body is fixed to the holder in advance in a centered state using a jig that is centered with the bearing holding part of the holder as a reference plane, before assembling the rotating shaft. A robot magnetic fluid seal structure characterized by: 2. The outer periphery of the jig is larger than the cylindrical first fitting surface that fits into the inner periphery of the bearing holding part and the first fitting surface that fits into the inner periphery of the magnetic fluid sealing body. 2. The magnetic fluid seal structure for a robot according to claim 1, further comprising a second fitting surface having a small diameter cylindrical shape. 3. The magnetic fluid sealing body includes a ring-shaped permanent magnet, a pair of ring-shaped pole pieces fixed to both ends of the permanent magnet and having an inner diameter smaller than the inner diameter of the permanent magnet, and supplied to the inner side of the permanent magnet. 2. The magnetic fluid seal structure for a robot according to claim 1, further comprising: a magnetic fluid that is held between the pole pieces by magnetic force. 4. The magnetic fluid seal structure for a robot according to claim 1, wherein the housing is a housing for a robot wrist, and the flange of the rotating shaft constitutes an output end of the robot wrist.