JPS62155748A - Varnish treatment method for motor - Google Patents

Abstract

PURPOSE:To eliminate the process of aftertreatment by holding varnish under the state, in which viscosity thereof is lowered at a specific temperature, dripping varnish and conducting thermosetting. CONSTITUTION:A stator 2 is placed on a frame 1 and immersed in a varnish tank in the varnish treatment of a small-sized motor. The inside of a winding 3 is impregnated with varnish, the winding is pulled up from the varnish tank and varnish is dripped, and the winding is heated and cured by a batch type furnace. Solventless varnish in which a thermosetting type curing catalyst as one part is added to 100pts. unsaturated polyester group varnish is used as varnish at that time. The temperature of the stator 2 is kept for 1hr at 80 deg.C, and thermo-set for 1hr at 130 deg.C. Accordingly, the generation of the marks of the adhesion of projecting varnish on the contact sections of the frame 1 with the stator 2 can be avoided, thus removing the process of the cut-off treatment process of the marks of adhesion.

Description

DETAILED DESCRIPTION OF THE INVENTION The industrial field of application relates to a method for varnishing small motors used for example in home appliances and equipment.

BACKGROUND TECHNOLOGY Small motors are treated with varnish for the purpose of mechanically reinforcing the windings and improving insulation performance. As a varnish treatment for a stator, a dipping impregnation method is often used in which the entire finished stator product after winding is immersed in varnish, pulled up, and then heated and dried. In recent years, unsaturated polyester-based solvent-free varnishes have come into use as varnishes for dipping and impregnation, with the aim of shortening the heating and drying time of varnishes.

The implementation state of the method for dipping and impregnating a solvent-free varnish will be explained with reference to FIG.

The finished stator product to be varnished is placed on stand 1 as shown in Figure 3.
and immerse it in a varnish bath for a specified period of time.

After the inside of the winding 3 is sufficiently impregnated with varnish, the pedestal is pulled up from the varnish tank at a constant speed, and the remaining drops are allowed to drip.
After that, it is placed in a batch furnace and heated at a predetermined curing temperature for a predetermined time to be cured all at once.

In general, solvent-free varnishes have strong adhesion (and if the treated stator is placed on a wire mesh, etc., the stator may stick to the pedestal and become difficult to remove after the varnish has hardened).

For this reason, as shown in FIG. 3, a frame 1 is often used in which a non-adhesive polytetrafluoroethylene (hereinafter abbreviated as PTFE) tube 1-b is covered on the surface of an iron round bar la.

Problems to be Solved by the Invention When varnish treatment is carried out in the above-mentioned situation, but if the batch furnace is started at the curing temperature as shown in Figure 2 during the heating and curing stage, as the atmospheric temperature in the furnace rises, the processing The salt content of the stator 2 also rises, and the varnish with reduced viscosity drips from the coil end 4 of the winding 3 of the treated stator 2 through the pedestal 1.

While the dripping continues, the temperature in the furnace atmosphere reaches close to the curing temperature of the varnish, resulting in protruding varnish adhesion marks several meters high on the coil end 4 of the post-curing treatment stator 2, as shown in Figure 4. 5 remained, and it was necessary to remove this adhesion mark 5 after the varnish treatment. The reason why the protruding varnish adhesion traces 5 remain as described above is due to a decrease in the viscosity of the varnish due to high temperature,
This seems to occur due to the balance between runoff dripping and varnish heating and hardening, and it tends to appear more prominently in stator cores with large thicknesses.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention uses an unsaturated polyester-based solvent-free varnish at a temperature lower than the temperature range in which a heat-curable catalyst effectively accelerates the curing of the varnish. The temperature of the heating furnace is maintained for a certain period of time while the varnish has a low viscosity at eye temperature, and after the varnish that adheres to the processing stator is sufficiently dripped down, the furnace temperature is raised to the curing temperature and the varnish is heated and cured. It is something.

Effect: By using the above method, the phenomenon in which protruding varnish adhesion marks remain on the coil end of the treated stator becomes much smaller than when the above method is not used, and after the varnish treatment, the protruding varnish adhesion marks are removed. No more work required.

As the example varnish, unsaturated polyester varnish 100
Varnish A to which 1 part of a heat-curable curing catalyst was added was used.

A characteristic diagram showing the tendency of the heating temperature and curing time of the varnish A is shown in FIG. This method involves placing a certain amount of varnish in a test tube, sealing it tightly, and immersing it in oil gas at a specified temperature, and determining the curing time based on the time it takes for the varnish to reach the peak of curing heat generation. It can be said that the effective operating temperature of the curing catalyst for Varnish A is 110°C or higher. Furthermore, this varnish A
The actual varnish curing conditions for the stator are as follows:
1 hour at 130°C.

On the other hand, even when the treated stator that had been immersed and impregnated at room temperature (0 to 40° C.) was placed in a heating furnace and held at 90° C. for 3 hours, the varnish attached to the treated stator did not gel.

Further, FIG. 6 shows the viscosity change characteristics of varnish A with respect to temperature. Those exceeding 10C,P at 80°C have high viscosity at room temperature and are unsuitable for dipping and impregnation at room temperature. Further 80℃
If the viscosity is less than IC, P, the viscosity is too low even at room temperature, and varnish adhesion is too small in immersion impregnation, which is unlucky in terms of mechanical reinforcement.

According to the results of the above preliminary confirmation, as shown in Figure 1, the varnish treatment was carried out using a heating furnace heating method in which the salt of the treated stator was held at 80°C for 1 hour and then heated and hardened at 130°C for 1 hour. Ta.

If the temperature is not maintained at 80°C for 1 hour during heating in the heating furnace, the outer diameter of the stator core where the protruding varnish marks were most prominent was 83wll111.
As a result of checking on a treated stator with an iron core thickness of 60III+1, the protrusion of the varnish adhesion mark was 0.5 mm at most.
It was within a moderate range and was a significant improvement.

Furthermore, as a result of examining the amount of varnish remaining on the treated stator after heating and hardening, it was found that the average amount of varnish impregnated before being put into the heating furnace was 6.
5% remained. This value can be said to be a sufficient amount compared to the approximately 30% remaining amount of oil-based solvent-based varnish used in the past, and is also sufficient in studies of noise and electrical characteristics of finished motor products. There were no problems and good characteristics were shown.

Effects of the Invention As described above, according to the present invention, it is possible to eliminate the protruding varnish adhesion marks on the pedestal abutting portion of the treated stator that often occur in the motor stator immersion impregnation method using unsaturated polyester-based, solvent-free varnish. It is possible to avoid this problem, and it is possible to eliminate the troublesome post-processing step of removing the protruding adhesion marks.

[Brief explanation of drawings]

Fig. 1 is a temperature rise pattern diagram of the heat curing furnace according to the present invention, Fig. 2 is a temperature rise pattern diagram of a conventional heat curing furnace, Fig. 3 is a state diagram showing the state of stator varnish treatment, and Fig. 4 is a partial cross-sectional view showing the occurrence of protruding varnish marks,
FIG. 5 is a heat curing characteristic diagram of varnish A according to this example, and FIG. 6 is a temperature-viscosity characteristic diagram of varnish A. Name of agent Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Temperature Jino

Claims (1)

[Claims] In the varnish treatment process, the stator windings are immersed in an unsaturated polyester-based solvent-free varnish and cured by heating. The treated stator is heated to a temperature higher than room temperature for 1 hour without the varnish hardening.
~10C. P. A motor varnish treatment method in which the varnish is held at a temperature that can reduce the viscosity for a certain period of time, and then heated and cured after the excess dripping has stopped.