JPS5813137Y2 - bearing structure - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bearing structure of a shaft formed by molding and a bearing portion.

In general, a shaft formed by molding and a shaft hole of a bearing that rotatably supports the shaft are each provided with a gentle draft angle to facilitate manufacturing.

To explain this with a diagram, in Figure 1a, 1 is a shaft molded from synthetic resin, and if the diameter of the base 2 is d and the diameter of the tip 3 is d', then the draft ad is axially It is gently formed in a straight line.

On the other hand, as shown in the same figure, in the shaft hole 11 of the bearing part 10 molded from synthetic resin that rotatably supports the shaft 1, the diameter of the tip part 12 and the diameter D' of the open end part 13 are
If so, a draft angle Ad is similarly formed.

By the way, the dimensions of shafts and bearings are generally controlled at the maximum diameter of the shaft, and at the minimum inner diameter of the bearing, and the necessary clearance is determined from the dimensions of both. These axes with slope 1
The dimension control of the bearing part 10, for example, design dimension control and inspection dimension, is the maximum diameter part of the shaft 1 on the protruding side, that is, the diameter d of the base part 2, and the minimum inner diameter part of the bearing part 10, that is, the diameter d of the base part 2. This is the inner diameter of the tip portion 12.

Therefore, in order to support the shaft 1 rotatably at llj 1 at the design stage, the design clearance between the shaft 1 and the shaft hole 11 is set to D-d.

However, since the actual clearance between the shaft 1 and the shaft hole 11 has a draft angle, D'-d or D-d'
, which is larger than the above design clearance.

This error with the design clearance is extremely small and causes almost no problem when the axial length t of the shaft 1 is relatively small, but as the axial length t increases, the difference between the shaft hole 11 and the shaft 1 increases. This has the disadvantage that the backlash increases, making it impossible to obtain a normal bearing structure.

The present invention was developed in view of the above-mentioned drawbacks of the conventional technology, and aims to provide a good bearing structure by supporting the shaft at two appropriately spaced points, minimizing the error with the design clearance. It is.

Hereinafter, the present invention will be explained in detail with reference to an embodiment shown in the drawings.

In Fig. 2a, the reference numeral 21 indicates the shaft according to the present invention, which is molded entirely of synthetic resin as in the conventional case, but its cross-sectional shape gradually increases in diameter from the base to the tip. Large, medium, and small cylinders 22 formed in a step-like shape with decreasing
, 23, 24.

These three cylinders 22, 23, and 24 are each provided with a draft angle having the same inclination.

On the other hand, as shown in FIG. It is formed by three holes 32, 33, and 34 of different diameters, the diameters of which become smaller in order.

Among these three holes, the holes 32 and 34 formed on the open end side and the tip side are shaft holes for supporting the shaft, and the minimum inner diameters D1 and D2, which are the standard dimensions, are at the base of the shaft 21.
and the maximum diameter d, which is the reference dimension of the shaft 22 and 23 of the tip.
1 and d2, and is designed to have an appropriate clearance.

The hole 23 formed in the middle of the housing is formed to correspond to the middle shaft 23 of the shafts 21, and its inner diameter is designed to have a sufficient clearance than the diameter of the shaft 23. It does not support the shaft 23 by loosely fitting it into the shaft 23.

With the above configuration, when the shaft 21 is inserted into the bearing part 31 and supported rotatably, the state shown by the two-dot chain line in FIG. 2a is obtained.

That is, the shaft 21 is supported in a sliding manner by the shaft 22 on the base side and the shaft 24 on the distal end side in the hole 32 on the open end side and the hole 34 on the distal end side of the shaft hole 31, respectively.

In this case, the axial length of the shaft support hole 32, 34 - gz
If the i button and t2 are shortened considering the strength as a bearing, the actual clearance between the shaft hole 31 and the shaft 21 Jλ1
The button and Aλ2 have almost no difference from the designed clearance.

As explained above, with this invention, the length of supporting the shaft can be selected appropriately regardless of the length of the shaft, and the error between the design clearance and the actual clearance can be minimized. In general, a bearing structure that is almost the same as a conventional bearing structure can be obtained, so a highly accurate bearing structure can be obtained especially when the load is large.

Furthermore, since the present invention utilizes the draft angle of the molded product to construct the support portion, the manufacturing cost is almost the same compared to the conventional method, and this has great effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional bearing structure, and FIG. 2 is a sectional view of the bearing structure of the present invention. 1.21...shaft, 11,31...bearing part, Aλ. Jλl, Jλ2...Actual clearance.

Claims (1)

[Scope of utility model registration request] It consists of a shaft that is formed by molding and has a draft from the base to the tip, and a bearing that rotatably supports this shaft and is formed by molding and has a draft from the deepest part to the opening. , a support part is provided near the deepest part and near the opening of the shaft hole of this bearing part to support the tip part and the base part of the shaft in a sliding state, respectively, and between these support parts, the middle part of the shaft and the base part are provided. Providing a loose fitting part that becomes loosely fitted,
A bearing structure characterized in that the length of the support part is formed to be shorter than the length of the play part in the axial direction.