JPH0320113A - Thermal expansion absorbing bearing - Google Patents

Abstract

PURPOSE:To decrease dimensional change to inside-diameter side due to expansion in an axial direction within respective temperatures and the degree of out-of-roundness by fitting a spiral plastic bearing into a holder provided with a spiral groove, and setting it non-fixed in the longitudinal direction. CONSTITUTION:A spiral groove is provided in a holder 12. A plastic bearing 11 is formed into a spiral shape to be fit into a holder 12, and its structure is made non-fixed in its axial direction and capable of making a free movement in a longitudinal direction. It is thus possible for the plastic bearing 11 to extend in a spiral direction within high temperature and shrink in the same direction within low temperature, so as to decrease inside-diameter dimensional change against temperature change and the degree of out-of-roundness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bearing structure that absorbs changes in inner diameter dimension due to heat. [Conventional technology] Conventional plastic bearings are fixed to the holder side with adhesive, or integrated with the inner surface of a cylindrical metal fitting by baking, gluing, or out-sert molding method, etc., and press-fitted into the holder side. The bearing inner diameter dimensions were determined by considering the initial clearance amount (the amount of gap between the inner diameter and the shaft). [Problems to be Solved by the Invention] According to the conventional plastic bearing described above, the amount of wall thickness expansion at high temperatures reduces the inner diameter, and at the same time, the amount of expansion in the length direction also decreases due to the fact that the outer periphery of the plastic bearing is bonded to the cylindrical metal fitting, etc. Because it was fixed, thermal stress was applied in a direction that expanded in the direction of reducing the inner diameter and worsened the roundness of the bearing. Even at low temperatures, the amount of contraction in the length direction is greater than the amount of contraction of the cylindrical metal fitting (the linear expansion coefficient is approximately one order of magnitude larger), so the inner diameter may be made smaller or the roundness may deteriorate as in the case of high temperatures. In order to absorb the above variation, it is necessary to provide a large clearance between the inner diameter of the plastic bearing and the shaft diameter.
There was play (backlash) between the bearing and the shaft, making it unsuitable for use in mechanical parts that require precision. [Means for Solving the Problems] The thermal expansion absorbing bearing of the present invention has a spiral arm in a holder, a plastic bearing in a spiral shape, and is fitted into the holder, has a non-fixed structure, and is free in the longitudinal direction. It is characterized by With the above structure, it can expand in the spiral direction at high temperatures and contract in the same direction at low temperatures, reducing the amount of change in internal diameter dimension and deterioration of roundness due to temperature changes. It can be done. Two spiral pickles provided in the holder. By using three threads, different types of plastic bearings having various characteristics can be combined.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

Fig. 1 shows a diagram of the parts structure, Fig. 1(a) shows a holder 12 having a spiral groove, and Fig. 1(b) shows a spiral-shaped plastic bearing 11. Figure 1(a)
The figure shows an example of a holder with one groove, and two and three grooves are not shown. FIG. 2 shows a completed drawing, and shows a mounting drawing of the spiral shaped bearing 11 inserted into the spiral arm of the holder 12. With this structure, changes in the bearing due to heat can be absorbed by changes in the length of the spiral 11, thereby reducing the effect on the inner diameter. [Effects of the Invention] As explained above, the present invention has a spiral-shaped plastic bearing inserted and mounted in a holder with a spiral groove (the shaft length direction is not fixed). This has the effect of reducing dimensional changes toward the inner diameter and deterioration of roundness due to directional expansion and contraction. 2 articles of Sviral Wei. Having three threads has the advantage of allowing bearing materials with different characteristics to be used in combination.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are perspective views showing the construction parts of an embodiment of the present invention, and FIG. 2 is a perspective view showing the complete training state. 11...Bearing, 12...Holder

Claims (1)

[Claims] A thermal expansion absorbing bearing characterized in that a spiral-shaped plastic bearing is fitted into a holder having a spiral groove, and the longitudinal direction of the shaft is not fixed.