JPS62109984A - Formation of insulating enamel layer - Google Patents

Abstract

PURPOSE:To improve the smoothness of the surface of enamel and to provide superior wear resistance by immersing a metallic substrate in a suspension contg. dispersed glass particles of a specified average particle size to electrodeposit the glass particles on the surface of the substrate by electrophoresis and by baking the substrate. CONSTITUTION:A metallic substrate is immersed in a suspension contg. dispersed glass particles of 2-7mum average particle size to electrodeposit the glass particles on the surface of the substrate by electrophoresis. The substrate having the deposited glass particles is taken out of the suspension and backed to form an insulating enamel layer. It is preferable that the glass contains >=15wt% oxide of an alkaline earth metal and <=2wt% oxide of a univalent alkali metal.

Description

[Detailed description of the invention] Industrial applications The present invention is a small board motor for a thermal head.

An insulating hollow that has a thin glass-ceramic layer coated on the surface of a metal substrate such as the bearing of an ultra-small motor or the sliding part of a mechanical seal, which has a smooth surface and can serve the purpose of insulating and abrasion-resistant the sliding part. Concerning layer formation method.

BACKGROUND ART The prior art will be explained in detail by taking a bearing of a small motor as an example. In recent years, small motors have progressed toward ultra-miniaturization, not only for household and industrial use, due to social needs for smaller, lighter, and thinner motors.
The proportion of coreless motors is increasing.

In FIG. 6, a shaft 6 has an arcuate tip and is rotatably supported by a sleeve-shaped radial bearing 9 provided on a frame 11. As shown in FIG. A commutator 7 is attached to a plurality of molded windings 6 integrally molded with a shaft 6 using a plastic molding material 8 to constitute a rotor. 12 is a magnet fixed to the frame 11 in opposition to the shaped winding 6; 13 is a yoke; 4 is a brush that makes sliding contact with the commutator 7; 14 is a placket that covers the end opening of the frame 11; A thrust bearing 1o for receiving the tip of the shaft 6 is provided at the center.

In the above configuration, the shaft 6 is supported by a sleeve-shaped radial bearing 9 and receives a load in the thrust direction by the thrust bearing 10 when rotating. What is the load that the thrust bearing receives at this time?

For example, in a system that uses magnetic force to apply a thrust load to prevent the rotor from moving up and down, the
gr, and in the case of a shaft with a diameter of 1 to 2 [LIm, the diameter at the tip thrust bearing contact part is 0.2ffI111
The load per unit area is 9.6 to 2 kgf.
/cJ. The thrust bearing 10, which receives the load and rotates at high speed, is extremely susceptible to wear. As a countermeasure for this, a partially stabilized film with excellent wear resistance /L/ :2 =:,
A. If the bearing is made of a ceramic material such as silicon carbide or alumina, the metal shaft will wear out. Additionally, ceramic bearings are difficult to miniaturize; they are thin and vulnerable to impact when miniaturized; improving impact resistance requires larger bearings, making it difficult to design ultra-compact motors. However, as a requirement of the times, impact resistance of 20 to 200 μm is required.

There was a desire to develop bearings with excellent wear resistance and insulation properties.

Table 1 shows the materials and wear amounts of bearings using conventional technology.

Impact resistance and current change amount are displayed.

The test conditions in Table 1 are as follows: 1) Test temperature: normal temperature 2) Number of revolutions
......2200 rpm3) Rated output...
・・・・・・・・・ 0.1W4) Voltage・・・・・・・・・
・4.2v6) Current value ・・・・・・・・・ IQQI
IIA.

In Table 1, the mark ◎ indicates excellent impact resistance.

An X mark indicates poor impact resistance. As shown in the results in Table 1, a bearing material with excellent wear resistance, impact resistance, and insulation properties has been desired.

Problems to be Solved by the Invention The present invention relates to a forming method for improving the smoothness, abrasion resistance, impact resistance, and insulation of the hollow surface of, for example, a bearing thermal head of a small motor, a mechanical seal, etc. It is.

Means for Solving the Problems The present invention uses a suspension in which glass-ceramic particles having an average particle size within the range of 2 μm to 7 μm are dispersed to improve the sliding of thermal bearing heads of small motors and mechanical seals. Glass ceramic particles are electrophoretically deposited on the functional surface of metal bases such as parts, etc., and fired to form a smooth insulating hollow layer, which reduces the amount of wear on bearings, reduces power consumption, and・It aims to reduce flutter and improve vibration noise.

Function By forming a smooth insulating hollow layer using a suspension in which glass ceramics having the above average particle size are dispersed,
The surface of the insulating hollow layer becomes smoother, and the dimensional accuracy is improved.As a result, the scissors and bearings maintain mutual insulation and do not wear out, improving reliability and extending the life of the motor. Furthermore, it becomes possible to design an ultra-small motor.

Example (1) Metal base glass ceramic coating layer is coated with metal base material on one or both sides. As the metal base material, ■low carbon steel plate for hollow holes, ■aluminized steel plate, ■stainless steel plate, and other similar steel plates can be used. However, the coefficient of thermal expansion of steel plate is 6
A steel plate within the range of 0 to 140X10/'C is preferable. In the following examples, a stainless steel i plate (svsa3o) was used.

(2) Glass ceramics Glass ceramics are wear resistant and impact resistant.

It must have excellent insulation properties. therefore,
Since the glass normally used for hollow products cannot be used, I used the glass from the third table.

(3) Method of forming an insulating hollow layer Fig. 3 illustrates a bearing according to an application example of the present invention. A glass-ceramic coating layer 2 is applied to the glass-ceramic coating layer 2. Note that elements common to those in the conventional example shown in FIG. 6 are given common numbers.

FIG. 1 is a process diagram showing a method for forming a smooth insulating hollow layer by electrophoresis. Glass material is 1260-1360
It is first melted at °C and then in a roll cooler to obtain a glass-ceramic kaleft.

This is pulverized using a pulverizer such as a ball mill. After this, some large particles were removed, and glass ceramic powder and isopropyl alcohol were added to a ball mill, and the glass ceramics were heated for a long time until the average particle size (6wt% value) in the weight cumulative particle size distribution reached 2 to 7 μm. The slurry is milled to create a suspension (slip) and placed in an electrophoresis tank.

In particular, the process of preparing this suspension is very important, and the method of preparing the suspension determines the quality of the surface and the ease of electrodeposition of glass-ceramic particles. The average particle size of the particles is best in the range of about 2 to 7 μm; if the particle size is larger than that (shown in Figure 4), the surface of the insulating wear-resistant layer will become rough and cause an increase in the amount of wear. . Furthermore, if the particle size is large, the adhesion strength between the electrodeposited particles and the metal is weak, resulting in sag of the glass-ceramic particles when the metal substrate is pulled up from the electrophoresis tank.

Small particle size ((a) in Figure 4) has the advantage of being able to be deposited with a small voltage and in a dense manner, but it is difficult to use a metal substrate on which glass-ceramic particles are deposited from an electrophoresis tank. When pulled up, the electrodeposited layer dries rapidly and has drawbacks such as peeling of the electrodeposited layer from the metal substrate. This is thought to be because the particle size is small, so naturally the surface area is also small, and as a result, the ability to hold alcohol becomes weak, causing the alcohol to evaporate rapidly.

As mentioned above, the process of preparing electrolyte is very important.
The milling time must be well managed. Formation of the electrodeposited layer on the base material is performed by depositing the metal base material on the second layer as shown on the right side of Figure 1.
The substrate 3 is cut into the shape shown in the figure (corresponding to Figure 3 and 3), and then degreased and cut into the shape shown in Figure 2 to carry out local partial electrodeposition.
Mask the part and the entire back side, place the device in an electrophoresis tank, and apply a voltage of 150 to 6 oooh with a distance between electrodes of 2 to 4 cfn.
Glass ceramic particles are electrophoretically electrodeposited at v, and after surface drying, they are fired at aOO to 960'C to obtain a smooth insulating hollow layer 2 of glass ceramics (corresponding to FIG. 3, 2). Grease is applied to the sliding surfaces.

A commutator 7 is attached to a plurality of molded windings 6 integrally molded with a shaft 6 using a plastic molded material 8 to constitute a rotor.

12 is a magnet fixed to the frame 11 in opposition to the molded winding 6; 13 is a yoke; 4 is a brush that makes sliding contact with the commutator 7; 3 is a motor case that covers the end opening of the frame 11; At the center of the bottom, a thrust bearing part 1 for receiving the tip of the shaft 6 is provided with a glass ceramic coating layer having insulation and wear resistance as a thrust bearing 2.

Next, a specific example will be explained.

<Example 1> Using glass A in Table 3, 400 g of glass powder and 11 g of isopropyl alcohol were put into a ball mill, and 20
Time milled. The average particle size of the glass powder in the suspension at this time was 2.0 μm. The particle size distribution is shown in FIG. 4 (b). Glass powder was electrodeposited onto a metal substrate using this suspension and fired at 860°C to form the motor shown in FIG.

<Example 2> Using the same glass as in Example 1, milling was carried out for 1Q time with the same input amount. The average particle size at this time was 7.0 μm. The particle size distribution at this time is shown in FIG. 4 (c).

A motor was then formed in the same manner as in Example 1.

Comparative Example 1> Milling was performed for 30 hours in the same manner as in Examples 1 and 2 to prepare a suspension with an average particle size of 1.0 μm, and this suspension was used for electrophoretic electrodeposition. - The resulting particle size distribution is shown in (a) of Figure 4.

However, when the metal substrate was pulled out of the suspension, the electrodeposited layer dried rapidly and cracks appeared on the surface.
After that, peeling occurred, so it was not possible to form an insulating hollow layer.

<Comparative Example 2> Milling was performed for 8 hours in the same manner as above,
A suspension having an average particle diameter of 8.0 μm was prepared, and the particle size distribution obtained when a motor was formed is shown in FIG.

The three motors in the above examples were evaluated as shown in Table 2. The evaluation test conditions for the various motors in Table 2 (test temperature, 9 rotations, etc.) were conducted under the same conditions as in Table 1.

(Hereinafter referred to as gold and white) The motor shown in Figure 1 is used for compact discs, etc. If the insulating hollow layer wears out by more than 30 μm, errors will occur in reading the disc and the motor will no longer function as a compact disc.

Therefore, this motor cannot be used as a product if it has a wear amount of 30/ljm or more, and Comparative Example 2 cannot be used.

Considering the above, in order to reduce the amount of wear on the insulating hollow layer, it is necessary to make the surface average roughness (R&) 0.3 μm or less, and in order to make Ra 0.3 μm or less, The average particle size of the glass ceramics in the suspension was 7.0μ.
It must be less than m.

However, if the average particle size is less than 2.0 μm, the deposited layer tends to peel off, so the appropriate particle size range is 2.0 μm.
~7. It turns out that it is Qμm.

<Example 3> A motor was produced under the same conditions as Example 1 using A-3 in Table 3 as the glass for insulating hollow shoes.

The amount of wear on these motors after 1000 hours was investigated, as well as the electrodepositivity and Vickers hardness of the glass.

The results of examining the dielectric strength and thermal expansion coefficient are shown in Table 3.

To summarize the results of various properties in Table 3: (1) In the composition of the glass, all monovalent alkali oxides (
Li2O, K2O, Na2O) is preferably in the range of 0.2 to 2 weight percent. 0.2% by weight or less is the limit for contamination with impurities, and it is difficult to synthesize glass with less than 0.2% by weight.
On the other hand, if it exceeds 2% by weight, the dielectric strength deteriorates rapidly, and the Pinkers hardness and wear amount of the glass ceramics also relatively deteriorate (R.

F, G, A, M, N, O, P).

(2) Amount of divalent alkaline earth metal oxides (BILO, M
gO.

The amount of oxides of (ao, ZnO) is preferably at least 15% by weight or more, and particularly preferably the total amount of oxides of divalent alkaline earth metals is 66% by weight or more. These relationships require a balance between the amount of monovalent alkali and the amount of divalent alkaline earth.

(3) When the amount of monovalent alkali in the glass ceramic is 2% by weight or less, electrophoretic electrodeposition is easy, and most of the properties such as Vickers hardness and wear amount are excellent (A,
B, J, Ni, L, Q).

(4) When the amount of monovalent alkali in glass ceramics increases, the electrolytic voltage during electrophoretic electrodeposition increases, and the withstand voltage also increases below 0.6 KY (G, N).

0, M).

(6) The coefficient of thermal expansion of glass in glass ceramics is 60 to 1a 6
10'/''C range is preferable.Glass (A, B, C) that can be electrophoretically deposited within this range and has excellent insulation and abrasion resistance.

D, E, F, H, I, J, L, P, Q) are preferable, and the combination can be determined by selecting the metal base material and glass and matching the coefficients of thermal expansion.

As shown in Table 3, depending on the composition of the glass, the insulating wear-resistant layers of the examples of the present invention exhibit excellent wear resistance as motor bearings.

<Example 4> In Example 1.2.3, an application example in which an insulating hollow layer according to an embodiment of the present invention was applied to a thrust bearing of a motor was described in detail, but the application could also be similarly developed to a substrate of a thermal head. is possible.

A suspension was prepared under the same conditions as in Example 1 using the glasses shown in Table 3. Using this suspension, 50% glass powder was prepared.
Electrodeposited on a metal substrate of ounX 100mm, 850'
C. to form an insulating hollow substrate.

A heating resistor, lead electrodes, and a wear-resistant layer were formed as thin films on this insulating substrate to fabricate a thermal head.

Comparative Example 3 As a comparative example, a heating resistor, a lead electrode, and a wear-resistant layer were formed on a conventionally used alumina glaze substrate (somm x 10mm) in the same manner as in Example 4.
A thermal head was formed.

The print densities of the above two thermal heads were compared. The results are shown in FIG. (A) in the figure is Example 4
(b) shows a conventional thermal head of Comparative Example 3. As can be seen from FIG. 6, the thermal head according to the embodiment of the present invention has higher print density than the conventional example, and can print more clearly with less electric power.

In the above embodiment, BaO is used as the substrate material.

Although MgO, (AO) and ZnO were used, practical effects can also be obtained with other alkaline earth metals.Also, isopropyl alcohol is used as an organic solvent for crushing and suspending glass ceramic materials.
Although organic solvents such as MIBK and isobutanol may be used, isopropyl alcohol is optimal in terms of handling and properties.

Effects of the Invention As detailed above, according to the present invention, the average particle size of the glass nanomix dispersed in the suspension is set to 2 μm to 7 μm,
By electrophoretically electrodepositing an insulating hollow layer using the suspension, the smoothness of the hollow hollow surface is further improved, and when used for motor bearings, it has excellent wear resistance, wow and flutter noise, and current resistance. It is possible to significantly improve the value, etc., and also to significantly contribute to the miniaturization of equipment, improved reliability, and extended life. Furthermore, when used as a thermal head, it is possible to form a thermal head at a lower cost and with excellent thermal efficiency.

[Brief explanation of drawings]

Fig. 1 is a process diagram showing a method of forming an insulating hollow layer according to an embodiment of the present invention, and Fig. 2 is a planar configuration in which an insulating hollow layer is formed on a thrust bearing portion of a motor case base material, which is an application example of the present invention. 3 is a cross-sectional configuration diagram of a small motor as an application example of the present invention, FIG. 4 is a graph showing the weight cumulative particle size distribution of glass particles, and FIG. 5 is a characteristic diagram showing the print density of the thermal head. FIG. 6 is a cross-sectional configuration diagram of a conventional small motor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 ■1 Figure 5 246 δ Pulse width ('ms) Figure 6

Claims (3)

[Claims] (1) A metal substrate is immersed in a suspension in which glass particles are dispersed, and glass particles are electrophoretically electrodeposited on the surface of the metal substrate,
The insulation comprises the step of firing the electrophoretically electrodeposited metal substrate to form an insulating hollow layer, and wherein the average particle size of the glass particles in the suspension is within the range of 2 μm to 7 μm. How to form a hollow layer. (2) Claim 1, characterized in that the glass contains at least 15% by weight or more of an oxide of an alkaline earth metal, and has a composition of 2% or less by weight of an oxide of a monovalent alkali metal. The method for forming the insulating hollow layer described above. (3) Center line surface roughness Ra of the insulating hollow layer is 0.3 μm
A method for forming an insulating hollow layer according to claim 1 or 2, characterized in that: