JPH06193636A - Bearing device for reciprocating motion - Google Patents

Abstract

PURPOSE:To combine a shaft having a low slide resistance with a molded bearing. CONSTITUTION:A shaft 1 for reciprocating in the axial direction and the molded bearing 2 of a molded article made of synthetic resin, and for receiving the shaft 1 are provided. The mean roughness of surface roughness of the shaft 1 is set to 0.1mum or less, while the maximum roughness is set to 0.6mum or less. Moreover the mean roughness of the surface roughness of the slide surface of the molded bearing 2 is set to 0.2mum or less, while the maximum roughness is set 0.1mum or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating bearing device in which a shaft for reciprocating motion and a bearing for receiving the shaft are combined, and, for example, to a device for bearing a drive shaft for driving a brush in an electric toothbrush. Is.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a structure which uses a molded bearing 2 of a synthetic resin molded product, which is a sliding bearing, as a bearing for supporting a shaft 1 which performs a rotary motion and an axial reciprocating motion. For example, in the case of an electric toothbrush, the shaft 1 is processed by drawing and centerless polishing, and the surface roughness of the shaft 1 is 0.24 μm in average roughness and 2.2 μm in maximum roughness. ing. The surface roughness of the sliding surface of the molded bearing 2 is 0.5 μm in average roughness and 3 μm in maximum roughness.

[0003]

However, in the current electric toothbrush, the surface roughness of the shaft 1 and the molded bearing 2 are both rough and the sliding resistance is large, which affects the power down and noise of the electric toothbrush. The present invention has been made in view of the above problems, and an object of the present invention is to combine a shaft with low sliding resistance and a molded bearing, and in the case of an electric toothbrush, power down and noise are less likely to occur. A bearing device for reciprocating motion is provided.

[0004]

To achieve the above object, a reciprocating bearing device of the present invention comprises a shaft 1 which reciprocates in the axial direction, and a molded bearing 2 which is a synthetic resin molded product which receives the shaft 1. , The average roughness of the surface roughness of the shaft 1 is 0.1 μm or less, the maximum roughness is 0.6 μm or less, and the average surface roughness of the sliding surface of the molded bearing 2 is 0.2 μm or less, The maximum roughness is 1 μm or less.

[0005]

According to the above construction, the surface roughness of the shaft 1 and the molded bearing 2 can be made fine to reduce the sliding resistance, and in the case of an electric toothbrush, power down can be prevented and noise can be prevented.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an electric toothbrush, in which a shaft 1 which reciprocates and rotates in a main body 3 is arranged so that its axial direction is oriented in the vertical direction, and the shaft 1 is made of synthetic resin. The bearing is supported by a molded bearing 2 made of a product. In the case of this embodiment, the shaft 1 is supported by two molded bearings 2. The shaft 1 serves as a drive shaft for the toothbrush, and the toothbrush is attached to the tip of the shaft 1. A motor 4 is installed in the lower part of the main body 3, and a motion converting mechanism 5 between the motor 4 and the shaft 1 is interposed.

The shaft 1 is made of a stainless steel material, for example, SUS304, SUS420J2 or the like. The surface roughness of the shaft 1 is finer than conventional ones, and the average roughness is 0.1 μm or less and the maximum roughness is 0.6 μm or less. The molded bearing 2 is made of resin such as polyolefin, nylon, fluorine, Teflon or the like. The surface roughness of the molded bearing 2 is also fine, the average roughness is 0.2 μm or less, and the maximum roughness is 1 μm or less. The material of the molded bearing 2 is
A coefficient of dynamic friction of 0.3 or less, good wear resistance, and P
The V value is 1400 Kg / cm ² · m / min or more. The PV value is a measure of the performance (especially lubricity) of the bearing. P is an abbreviation for pressure, which is a load applied to the bearing, and V is an abbreviation for velocity, which is the peripheral speed of the rotating shaft. PV value = P × V. The larger the value, the better the performance.

Table 1 shows a comparison of power down values (values of reduction in rotation speed between no load and load) and noises due to combinations of surface roughness of the shaft 1 and the molded bearing 2 in the case of an electric toothbrush. In Table 1, experimental NOs. 1 and 3 indicate conventional examples, experimental NO. 2 indicates comparative examples, and experimental NOs. 4 and 5 indicate examples of the present invention.

[0009]

[Table 1]

From these results, it can be seen that the power down and the noise are reduced as the surface roughness of the shaft 1 and the molded bearing 2 is reduced.

[0011]

As described above, the present invention sets the average surface roughness of the shaft to 0.1 μm or less and the maximum roughness to 0.6 μm or less, and the average surface roughness of the sliding surface of the molded bearing. Roughness 0.2μ
Since the maximum roughness is less than m and the maximum roughness is less than 1 μm, the combination of the shaft and the molded bearing has a small surface roughness, and the sliding resistance is small. It is possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a conventional example.

[Explanation of symbols]

 1 shaft 2 molded bearing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Go Tsuchiya 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (1)

[Claims] 1. An axially reciprocating shaft and a molded bearing of a synthetic resin molded product for receiving the shaft, the average surface roughness of the shaft is 0.1 μm or less, and the maximum roughness is 0. .6 μm
Below, the average roughness of the surface roughness of the sliding surface of the molded bearing was set to 0.
A bearing device for reciprocating motion having a maximum roughness of 2 μm or less and a maximum roughness of 1 μm or less.