JPH02223356A - Small-sized motor brush and its manufacture - Google Patents

Abstract

PURPOSE:To prevent peeling off of a vibration damper and deterioration of vibration-damping properties in a high-temperature atmosphere by forming a vibration damper layer to be laminated on a brush surface from a photo- setting resin. CONSTITUTION:The tip side of a plate brush body 1 comes in sliding contact with a commutator and the rear end side thereof is fixed to a supporting material and a vibration damper layer 5 composed of a photo-setting resin is formed on the brush body. In order to form the vibration damper layer 5, the specified part of the brush body 1 is coated with a photopolymerizable polymer being a vibration damper composition by a dispenser and ultraviolet rays are applied to the part singly or while the rays are being cooled to harden the vibration damper composition to form the composition into the vibration damper layer. In this case, the photo-setting resin is little in lowering of vibration-damping characteristics and adhesion in a heating atmosphere. In this manner, even if a small-sized motor brush is used in a high temperature atmosphere continuously for a long time, good vibration-damping characteristics can be maintained without making a noise due to vibration larger and causing sparks due to chattering.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brush for a small motor used in audio-video equipment, office automation equipment, etc., and a method for manufacturing the same.

[Conventional technology]

Generally, the brushes of a small motor slide on the outer periphery of a cylindrical commutator to conduct electricity between the rotor and an external circuit. In such brushes, as the commutator rotates, the contact portion thereof vibrates and generates abnormal noises and sparks due to the chattering phenomenon, so measures have been taken to prevent vibrations. For example, as shown in FIGS. 3 and 4, a vibration damping material 4 is constructed by laminating an adhesive material 2 in the form of double-sided tape and a viscoelastic material 3 made of a rubber elastic piece on a brush body 1. In figure 0, where the
A is a commutator. The adhesive material 2 in the form of double-sided adhesive tape is also called a pressure-sensitive adhesive material, and can be easily adhered with a light pressure such as finger pressure, and an acrylic or rubber-based solvent-based adhesive material is used. This adhesive material 2 itself also has considerable vibration damping properties. The viscoelastic material 3 laminated on the adhesive material 2 is butyl rubber or chlorosulfonated polyethylene rubber.

Examples include vulcanized rubber such as fluororubber and chloroprene rubber, and cured resins such as urethane elastomer and urethane foam. This viscoelastic material 3 exhibits high vibration damping properties (vibration damping properties) by converting vibration energy into thermal energy in the vicinity of the glass transition point, and forms the core of the vibration damping material.

[Problem that the invention seeks to solve]

In such conventional brushes for small motors, in the vibration damping material 4 made of the adhesive material 2 and the viscoelastic material 3, the adhesive material 2 in particular decreases in viscosity significantly in a heated atmosphere, causing it to peel off. This poses a problem in that the damping performance is significantly reduced, and the performance of the damping material 4 as a whole is thereby deteriorated. In addition, as described above, adhesive material 2
When attaching the damping material 4 made of the and viscoelastic material 3 to the brush body 1, most of the work is done manually, which makes the work complicated and increases the cost. In addition, in some cases pasting is done by robots, but in order to ensure ease of handling, we have overcome new problems such as improving the precision of the molding dimensions of the damping material 4 and taking measures to prevent adhesion to the robot hand. In some cases, these problems have led to the use of materials that sacrifice damping properties.Therefore, even when used in heated atmospheres, damping materials are There is a need to provide a small motor brush that does not peel off or deteriorate its damping properties, and has good workability for attaching damping materials.

The present invention was developed in view of these circumstances, and it does not cause the damping material to peel off or its damping performance deteriorates even in high-temperature atmospheres, and it also improves the workability of installing the damping material. The purpose is to provide a good small motor brush and its manufacturing method.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a plate-shaped brush body whose front end side slides on a commutator and whose rear end side is fixed to a support member, and a damping material laminated on the brush surface of the plate-shaped brush body. The first feature is a small motor brush in which the vibration damping material layer is made of a photocurable resin, and the following special vibration damping material composition is coated on the plate-shaped brush body in a layered manner. The second gist is to manufacture the above-mentioned small motor brush by curing it by irradiating it with ultraviolet rays.

(A) At least one of a photopolymerizable prepolymer and a photopolymerizable monomer.

(B) Photopolymerization initiator.

[Effect]

In the small motor brush of the present invention, the damping material layer is composed of a photocurable resin, and since the photocurable resin has little deterioration in damping properties and adhesive strength in a heated atmosphere, it can be used at high temperatures for a long period of time. Demonstrates good vibration damping characteristics even when used in an atmosphere. Therefore, even if the small motor brush of the present invention is used for a long period of time in a high temperature atmosphere, it maintains good performance without increasing noise or generating sparks due to chattering.

Further, according to the manufacturing method of the present invention, a special vibration damping material composition characterized by the above-mentioned components (A) and (B) is coated on the plate-shaped brush body in a layered manner, and then ultraviolet rays are irradiated. By curing, the conventional complicated work for forming a damping material layer becomes unnecessary, and the manufacture of the brush can be extremely simplified.

〔Example〕

An example of the small motor brush of the present invention is shown in FIGS. 1 and 2. In the figure, 1 is a plate-shaped brush main body, and 5 is a damping material layer made of a photocurable resin formed thereon. In this case, in order to maximize vibration damping performance, in the plate-shaped brush main body whose tip is divided into three parts from approximately the center by a notch along the longitudinal direction, the length of the three divided parts is A, The length of the remaining plate-shaped portion is B, and the length from the tip side of the damping material layer 5 to the base of the divided part of the plate-shaped brush body 1 is defined as C. Let D be the length of the part located above the plate-like part of the plate-like brush body 1, and let E be the length from the tip of the divided part of the plate-like brush body 1 to the contact part with the commutator A. , D, and E are set to the following values.

A=1-4B, preferably A=1-28C=1/3-2
/3A, preferably 1/2AD=O~2/3B, preferably 1/2BB=1/8~3/8A, preferably 1/4
A. The small motor brush as described above is manufactured, for example, in the following manner.

That is, first, a damping material composition containing the above-described components (A) and (B) as main components is prepared, and a plate-shaped brush main body 1 having a shape as shown in FIG. 1 is prepared. Next, the above-mentioned vibration damping material composition is applied to a predetermined part of the plate-like brush body l using a dispenser or the like, and then ultraviolet rays are applied alone using an ultraviolet irradiation device or by cooling (damping before curing due to the heat generated by the ultraviolet lamp). In order to prevent the damping material composition from flowing down from the brush due to a decrease in the viscosity thereof, the damping material composition is irradiated to harden the damping material composition to form a damping material layer. In this case, the vibration damping material composition has a viscosity of 10! ~10' c ps is preferably set to 10' to 10'' cp. By forming the damping material layer 5 in this way, the damping material layer 5 can be formed by an extremely simple operation compared to the conventional example. can be easily configured and easily adapted to automation.

To explain the above vibration damping material composition in more detail, the above vibration damping material composition is obtained using one or both of a photopolymerizable polymer and a photopolymerizable monomer (component A) and a photopolymerization initiator CB acid component. .

Examples of the photopolymerizable prepolymer include polyester acrylate and polyurethane acrylate.

Examples include acrylic acid esters (acrylates) such as epoxy acrylate, polyether acrylate, and silicone acrylate. These may be used alone or in combination. However, among these acrylic esters, polyurethane acrylate is preferable from the viewpoint of vibration damping properties, and in particular, polyurethane acrylate has a viscosity of 1 at 25°C.
Those within the range of 0'' to 10'cp exhibit the best vibration damping properties.

Examples of the photopolymerizable monomer include monofunctional acrylates such as lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 1,6-hexanediol diacrylate, and dicyclopentadiene acrylate. In addition, polyfunctional compounds such as dicyclopentenyloxyethyl acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol acrylate Acrylates can be mentioned. These compounds may be used alone or in combination without any problem. Particularly suitable photopolymerizable monomers include 2-ethylhexyl acrylate and trimethylpropane triacrylate.

The photopolymerization initiator [component (B)] that initiates the photopolymerization reaction of the photopolymerizable prepolymer and photopolymerizable upper polymer includes benzyl dimethyl ketal, benzophenone, 1-hydroxycyclohexylphenyl ketone, Michler ketone, Examples include benzoin and benzyl, which can be used alone or in combination.

The photopolymerizable prepolymer and photopolymerizable monomer of the above component (A) are used alone or in combination, and the ratio of this component (A) to the photopolymerization initiator of the above component (B) is the total of component (A) and component (B) as 1
It is preferable that the (A) component is about 95±3% and the (B) component is about 5±3% when 00 focused view% (hereinafter abbreviated as "%") is set. A photopolymerizable prepolymer and a photopolymerizable monomer are used as the component (A), and both are preferably used in combination. in this case,
The mutual ratio of the photopolymerizable prepolymer and the photopolymerizable monomer is preferably such that the former accounts for 20 to 80% of the total component (A). However, as the proportion of the photopolymerizable prepolymer increases, the viscosity of the entire vibration damping composition improves, which also improves workability. is set to be larger than the photopolymerizable monomer.

In addition to the above-mentioned component materials, the vibration damping material composition of the present invention may optionally contain an aggravating agent, an inorganic filler, a pigment, a thixotropic agent, a tackifier, etc.

The damping material composition of this invention contains the above component (A).

(B) Blending the ingredients and other necessary materials in a predetermined ratio,
It is easily manufactured by applying it to a normal mixer or homogenizer. Then, as mentioned above, it is applied to the brush body using a dispenser or the like, and at this time, the viscosity is set so that it can be applied thickly. As mentioned earlier, this viscosity is 10 at 25°C.
"~10?cp1 is preferably set to 104~10'cp. That is, if the viscosity is within this range, for example, the tip of the brush body 1 will branch into three forks as shown in FIG. Even when the vibration damping material composition is formed into a thick wall, it can be formed into a thick wall without flowing down from between the parts.After the damping material composition is formed into a thick wall in this way, By irradiating ultraviolet light with an irradiation device,
Curing and adhesion are simultaneously performed on the target portion of the brush body 1 to form a vibration damping material.

Next, manufacturing examples of small motor brushes will be described together with comparative examples.

[Manufacturing example]

A damping material composition was prepared by blending the raw materials shown in Table 1 below in the proportions shown in the same table and mixing them in a mixer.

(Hereinafter, blank spaces) Next, the vibration damping material composition was applied directly onto the brush body 1 using a dispenser, and then was irradiated with ultraviolet rays from an ultraviolet irradiation device to be cured to form a vibration damping material 5. The characteristics of the damping material 5 thus obtained and the moldability results described above are shown in Table 2.

(Left below) As is clear from Table 2, the separately manufactured products have superior vibration damping properties compared to the comparative products.・Both the noise level and adhesive strength are good, and moreover, even in a heated atmosphere. It can be seen that the damping characteristics do not deteriorate over time.

〔Effect of the invention〕

Since the small motor brush of the present invention is configured as described above, it maintains good performance even when used continuously in a high temperature atmosphere for a long time without increasing noise or generating sparks due to chattering. According to the manufacturing method of the present invention, a special vibration damping material composition characterized by the above-mentioned components (A) and (B) is coated in a layer on the plate-shaped brush body, and then cured by irradiation with ultraviolet rays. By doing so, there is no need for the conventional complicated work to form the damping material layer.
This greatly simplifies the manufacture of brushes.

[Brief explanation of the drawing]

Fig. 1 is a plan view of one embodiment of this invention, and Fig. 2 is the same (
3 is a plan view of the conventional example, FIG. 4 is a longitudinal sectional view thereof, and FIG. 5 is an explanatory diagram of noise level measurement. 1... Brush body 5... Vibration damping material

Claims (2)

[Claims] (1) A plate-shaped brush main body whose front end side is in sliding contact with a commutator and whose rear end side is fixed to a support material, and a damping material layer laminated on the brush surface of the plate-shaped brush main body, the damping material layer but,
A small motor brush characterized by being made of photocurable resin. (2) Prepare a damping material composition containing the following components (A) and (B) as main components, prepare a plate-shaped brush body, and layer this damping material composition on the plate-shaped brush body. A manufacturing method for a small motor brush, which is characterized by applying a coating to the surface and then curing it by irradiating it with ultraviolet rays. (A) At least one of a photopolymerizable prepolymer and a photopolymerizable monomer. (B) Photopolymerization initiator.