JPH043442Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to varistor porcelain constituting a ring-shaped varistor used for extinguishing sparks in small motors.

[Prior Art] Typical porcelain for varistors is made of a ring-shaped sintered body made of semiconductor strontium titanate, and a plurality of electrodes are formed on the surface of the ring-shaped sintered body to form a varistor. Until now, varistors used to eliminate sparks in small motors have been constructed by forming multiple electrodes on the main surface of the porcelain. Some proposals have been made in which electrodes are formed.

The latter varistor is usually manufactured by the following method. That is, between the electrodes on the circumferential surface of the porcelain
A resist film is formed in the area where the resist film becomes, and a conductive paste is uniformly applied thereon. Next, the resist film is removed, the conductive paste is divided into a plurality of parts, and the conductive paste is baked to form electrodes.

However, the electrode formed by the above method has burrs on both ends thereof, and is easily peeled off from there.

Therefore, as shown in FIG. 6, a porcelain 1 having grooves 3 formed in the thickness direction so as to divide the circumferential surface 2 into a plurality of parts was used, and as shown in FIG.
A method has been proposed in which a conductive paste p is transferred from a roll r onto the circumferential surface of the porcelain 1 to form electrodes divided by the grooves 3.

[Problems to be solved by the invention] However, in the roll transfer of the conductive paste, as shown in FIG. 7, the conductive paste p is scraped off from the roll r at the edge of the groove 3, The conductive paste p accumulates at the groove 3, and the other edge of the groove 3 flows and comes into contact with the conductive paste p applied to the other peripheral surface partitioned by the groove 3. For this reason, adjacent electrodes may be shot or a discharge may occur when a high voltage is applied between the electrodes, making it impossible to obtain a sufficient spark extinguishing effect.

The purpose of this invention is to solve the above-mentioned problems in conventional varistor porcelain.

[Means for solving the problem] That is, the porcelain for barista according to this invention is the first
As shown in FIGS. 5 to 5, in a disc-shaped porcelain 11 having grooves formed in its thickness direction to divide the circumferential surface 12, the circumferential surface 12 and the groove surface 13 is formed by a smooth curved surface 14 whose inclination angle with respect to the peripheral surface 12 gradually increases.

[Function] When applying the conductive paste p for electrode formation to the circumferential surface of the porcelain 11 by the roll transfer method, as shown in FIG. It tends to accumulate in the area where the circumferential surface 12 of the groove 11 and the groove surface 13 are connected. but,
Since this portion is formed by a smooth curved surface 14, when a certain amount of conductive paste p accumulates here, the paste p is attached to the roll r and the circumferential surface of the porcelain 11 due to its adhesion to the roll r. and the circumferential surface of the porcelain 11. Therefore, a large amount of the conductive paste P does not accumulate on the groove surface 13 side, and the conductive paste P is applied almost uniformly to the circumferential surface 12 of the porcelain 11.

[Example] Next, an example of this invention will be described with reference to FIGS. 1 to 5.

In the embodiment shown in FIGS. 1 to 3, semicircular grooves are formed at equal intervals on the circumferential surface 12 of the porcelain 11, and the boundary between the circumferential surfaces 13 and 12 is formed into a smooth circular arc surface. It is formed.

Figure 2 shows a conductive paste p on the peripheral surface 12 of the porcelain 11.
This shows the state when the groove surface 13 is transferred by roll.
Since the boundary portion between the outer surface 12 and the outer surface 12 protrudes from the outer portion, the conductive paste p accumulates here. However, on the other hand, the conductive paste p adheres to the circumferential surface of the roll r and the circumferential surface 12 of the porcelain 11, and is drawn between them along the smooth curved surface 14.

In the embodiment shown in FIG. 4, the groove has a rectangular shape, and in the embodiment shown in FIG. 5, the groove has a V-shape. In either case, the groove surface 13 and the circumferential surface 12 are connected by a smooth curved surface 14, as in the above embodiments.

[Effect of the invention] As explained above, according to this invention, porcelain 1
When the conductive paste p is roll-transferred onto the circumferential surface 12 of the substrate 1, a large amount of the conductive paste p does not accumulate on the edge of the groove. Therefore, problems such as excessive conductive paste p flowing out to another adjacent electrode side, causing shortening between the electrodes or discharge, do not occur.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of varistor porcelain showing an embodiment of this invention, and FIG. 2 is an enlarged cross-sectional view of essential parts showing the state when conductive paste is roll transferred to the same porcelain.
Figure 3 is an enlarged view of part A in Figure 1, Figures 4 and 5 are enlarged views of grooves showing various shapes of grooves in porcelain for varistors, and Figure 6 is a perspective view of a conventional example of porcelain for varistors. , FIG. 7 is an enlarged sectional view of the main part showing the state when the conductive paste is roll-transferred to the same porcelain. 11...Porcelain, 12...Surrounding surface, 13...Groove surface,
14...Curved surface.

Claims (1)

[Scope of utility model registration request] In a varistor porcelain having grooves formed in the circumferential surface 12 of a disk-shaped porcelain 11 in the thickness direction so as to divide the circumferential surface 12, the circumferential surface 12 and the groove surface 1
3 is formed by a smooth curved surface 14 whose inclination angle with respect to the peripheral surface 12 gradually increases.