JPH04113022A - Structure for pressurizing ball bearing apparatus - Google Patents

Abstract

PURPOSE:To simplify assembly by providing a cylindrical pressurizing spacer formed of a shape memory material and provided with a cut along an axial direction between outer wheels which are separated from each other along the axial direction. CONSTITUTION:A ball 3 is placed in an orbit groove 1a of a shaft 1 to fit an outer wheel 5, and a pressurizing spacer 7 is provided between the outer wheels 5,5. The pressurizing spacer 7 is a cylinder formed of a cool-shrinking shape memory resin for example and is provided with a cut along an axial direction. At the time of assembly, after the outer wheels 5,5 are fitted, the pressurizing spacer 7 which has been cooled to have the cut opened is interposed between the outer wheels 5,5 and left until its temperature reaches the ambient temperature. The pressurizing spacer is slightly larger than a size H between the outer wheels, thereby applying pressure to the outer wheels. Therefore assembly is simple.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a preload structure for a rolling bearing device, and particularly to one suitable for precision shaft units used in hard disk drives, optical disks, VTRs, etc.

[Conventional technology]

As shown in Fig. 3, a conventional precision shaft unit has two rows of raceway grooves (1a) spaced apart on the outer peripheral surface of the shaft (1).
The outer ring (5) is attached to the outer ring (5) via the rolling element (3).
) and (5), a preload is applied to the bearing portion by a coil spring (16) installed via a spring seat (15).

[Problems to be solved by the invention] Precision shaft units require many assembly processes that are difficult to automate, such as incorporating rolling elements between the outer ring and raceway groove, and installing coil springs between the outer rings, which reduces product costs. Cost matters a lot. Moreover, since precision shaft units are mainly used as spindles for information equipment, their parts are small in size and assembly work is difficult.

As mentioned above, in conventional precision shaft units, a preload is applied to the bearing by a coil spring interposed between the outer rings, and this coil spring is installed using the following procedure (see Figure 4). ).

■ After assembling one side of the bearing, place the shaft (1) in the jig (2).
0) and fix it (see figure a).

■ Insert the spring seat (15), coil spring (16), and spring seat (15) into the shaft (1) in this order (C in the same figure).

(2) Place the base (21) on the top of the jig (20), compress the coil spring (16) using the holding plate (22), and then assemble the other bearing part (FIG. 1 and d).

As described above, mounting the coil spring requires the difficult task of assembling the other bearing while compressing the coil spring. Furthermore, there is a restriction that the distance H between the outer rings cannot be made smaller than a certain level due to the dimensions of the coil haft and the heel 7 seat, and due to the interposition of a presser plate during assembly.

On the other hand, in order to solve the above-mentioned problems, Japanese Utility Model Application Publication No. 64-53619 discloses a vehicle in which a preload ring made of shape memory resin or shape memory alloy is interposed between the outer rings. However, this preload structure still has poor workability because it is necessary to assemble the other bearing part after inserting the preload ring, and the axial deformation of the preload ring is required due to the assembly work of the bearing part. Since it is necessary to set a larger number than the above, the generation of residual distortion after returning to the original shape becomes a problem. To explain with reference to FIGS. 4 and 4, the rolling elements (3) are connected to the outer ring (5) and raceway groove (1a)
When inserting the outer ring (5) between the
22a) on the inner diameter surface of the outer ring (5). Therefore, even in this preload structure,
It is essential to interpose a presser plate between the outer ring and the preload ring during assembly, and the required amount of axial deformation of the preload ring must be set to a value that also includes the axial width dimension of the presser plate.

Therefore, the purpose of the present invention is to ■ Simplification and efficiency of assembly work ■ Reducing the distance between outer rings ■ Preventing residual distortion It is in.

[Means to solve the problem]

In the present invention, a preload spacer, which is formed by providing an axial cut portion in a part of a cylinder made of a shape memory element material, is interposed between the outer ring. As the shape memory element material, for example, a shape memory resin or a shape memory alloy that returns to its original shape at room temperature can be considered.

[Effect]

The preload spacer is made of a shape memory element material and is provided with an axial cut section, so when it contracts under certain conditions, the axial width decreases, and further circumferential contraction causes the cut section to shrink. Open your mouth. The preload spacer is further elastically enlarged through this open cut portion, and is interposed between the outer ring from the side surface of the shaft. That is, the preload spacer is installed after the bearing section is assembled. After installation, when the preload spacer is returned to its original shape under the initial conditions, the preload spacer applies preload to the bearing by pressing the outer ring in the axial direction with its end face, and then closes the cut portion again to release the bearing. acts as a seal.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure shows a precision shaft unit equipped with a preload structure according to the present invention. This precision shaft unit consists of a shaft (1) with a pair of raceway grooves (1a) formed on its outer circumferential surface, a shaft (1) with a pair of raceway grooves (1a) formed on the outer peripheral surface;
), a cage (4) that holds the balls (3) at equal intervals around the circumference, and an outer ring (5) fitted into the raceway groove (1a) via the balls (3). ), a seal (6) attached to the non-opposed end of the outer ring (5), and an outer ring (
5) Consists of a preload spacer (7) interposed between (5).

The preload spacer (7) is a cylindrical member made of a shape memory element material, such as a shape memory resin that shrinks when cooled, and has an axial cut portion (7a) in a part thereof, as shown in FIG. 2A. is provided. When this preload spacer (7) is cooled to a predetermined temperature, the axial width dimension is reduced and the cut portion (7a) is opened, as shown in FIG. 2B. The axial width dimension is set to a value that is slightly smaller than the dimension H between the outer rings when contracted and slightly larger than the dimension H between the outer races when restored to its original shape. In addition, an outer ring (5) is provided on both end surfaces of the preload spacer (7).
Pilot part (7) that can fit into the seal groove or inner diameter surface of
b) is formed.

The preload spacer (7) is installed by cooling the preload spacer (7) to a predetermined temperature, then elastically pushing out the open cut portion (7a) and installing it onto the shaft (1) from the side. That is, this preload spacer (7) is inserted after the fitting work of both outer rings (5) (5) is completed. Then, the interposed preload spacer (7) is heated or left until it reaches room temperature, that is, until it returns to its original shape. Preload spacer (7)
Since the axial width dimension of is set to be slightly larger than the outer ring distance dimension H at room temperature, the preload spacer (7
) is elastically deformed in the axial direction by this dimensional difference (H-h),
The outer ring (5) is pressed by the elastic restoring force. In addition, the preload spacer (7) has a cut portion (7) that extends in the circumferential direction and is open.
Close a). At this time, part of the inlet (7b) is connected to the outer ring (5).
) is fitted into the seal groove or inner diameter surface of the Therefore, the preload spacer (7) applies a predetermined amount of preload to both bearings, and also functions to seal the bearings.

In addition, when the preload spacer (7) is formed of a heat-shrinkable shape memory resin, the preload spacer (7) is heated and contracted in advance, and the preload spacer (7) is inserted between the outer rings (5) (5). After that, cool or leave it to room temperature.

Further, the preload spacer (7) may be formed of a shape memory alloy that is shrinkable by cooling or shrinkable by heating.

Although examples using a shape memory element material using temperature conditions as a parameter have been described above, the present invention is not limited thereto. It is also possible to construct a preload structure according to the invention.

〔Effect of the invention〕

The present invention has the following effects.

■ After all the assembly work of the bearing part is completed, it becomes possible to insert a preload spacer, which greatly simplifies and improves the efficiency of the assembly work.

■ The cut portion of the preload spacer opens during installation and closes after installation, so the preload spacer itself also has a sealing function. Therefore, the conventional spring seat is not required, and the number of parts can be reduced and the efficiency of the assembly work can be further improved.

■ Since coil springs and spring seats are not required, and there is no need to interpose a presser plate between the outer rings during assembly, the distance between the outer rings can be reduced compared to conventional models.

■ Since there is no need to use a presser plate during assembly, the necessary axial deformation of the preload spacer is equivalent to the amount of preload, and the generation of residual strain, which was a problem in the past, is eliminated. Avoided.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a precision shaft unit equipped with a preload structure according to the present invention, Figs. 2A and 2B are a front view and a longitudinal sectional view of a preload spacer, and Fig. 3 is a precision shaft unit equipped with a conventional preload structure. A cross-sectional view of the precision shaft unit, and FIG. 4 is a schematic diagram showing the procedure for installing the coil spring. 1 - Shaft 3 - Rolling element 1a: Raceway groove 5 Outer ring 7 - Preload spacer

Claims (1)

[Claims] (1) A rolling bearing device in which a preload spacer is interposed between outer rings that are spaced apart in the axial direction, and is made of a cylinder made of shape memory element material with an axial cut section. Preload structure.