JPS61142621A - Manufacture of temperature fuse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention - No. 1 This invention relates to a method for manufacturing a temperature fuse, in particular a method for manufacturing a temperature fuse, in which a fusible alloy is fixed between the tips of a pair of lead wires, and a flux is applied to the surface of the fusible alloy. It is used when manufacturing a thermal fuse sealed in an insulating case.

i匪Δ11 This invention is a temperature fuse in which a fusible alloy is fixed between the ends of a pair of lead wires, and the surface of the fusible alloy is coated with flux and sealed between an insulating case. This method involves fixing a fusible alloy between the tips of a pair of lead wires, and then knurling the surface of the fusible alloy to form an uneven surface. Afterwards, the surface of the fusible alloy is filled.

It is used to cover the wood.

BACKGROUND: Modern electrical equipment has come to have built-in temperature rise prevention devices in order to prevent burnout and fires caused by abnormalities in the electrical equipment itself. Among these types of excessive temperature rise prevention devices, temperature fuses that use a fusible alloy that melts at a specific temperature are the simplest in structure and inexpensive, and are most commonly used.

Figure 2 is disclosed in Utility Model Application Publication No. 58-338,
1 shows a typical cross-sectional view of a conventional fusible alloy type temperature fuse. In the figure, numerals 1 and 2 are a pair of lead wires made of copper, the surfaces of which are plated with Hirata or the like.

Reference numeral 3 denotes a fusible alloy that melts at a specific temperature and is fixed between one end of each of the lead wires 1 and 2 by means such as welding. Reference numeral 4 denotes a flux for preventing oxidation that is applied to the tips of the lead wires 1 and 2 and to the surface of the fusible alloy 3. Reference numeral 5 denotes a cylindrical insulating case made of ceramic or the like, which is sized to form a sufficient gap with the fusible alloy 3.

Numerals 6 and 7 are sealing resins made of epoxy resin or the like, which fix the lead wire 1.degree. 2 to the insulating case 5 and seal the space between the two.

In the above structure, both lead wires 1.degree. 2 are electrically connected via the fusible alloy 3 at room temperature, and electricity is supplied to the electrical equipment through this temperature fuse.

However, when the ambient temperature rises due to an abnormality in the electrical equipment and exceeds the melting point of the fusible alloy 3, the fusible alloy 3 melts and the melted fusible alloy 3 is transferred to the lead wire 1 as shown in FIG. , 2 aggregates due to surface tension to form a sphere 3a,
3b, the lead wires 1 and 2 become non-conductive, the circuit is opened, and power to the electrical equipment is stopped. When the ambient temperature decreases accordingly, the spheres 3a and 3b made of the fusible alloy in the molten state solidify as they are.
The circuit remains open, preventing electrical equipment from overheating and preventing dangers such as fire.

B.

By the way, in the above-mentioned temperature fuse, since the fusible alloy 3 has a simple cylindrical shape, when the flux 4 is applied, it is difficult to coat it with a uniform thickness due to the flow of the flux 4. In addition, if the temperature is kept at a high temperature slightly lower than the operating temperature for a long time, the flux 4 deposited on the surface of the fusible alloy 3 will melt, and the fusible alloy 3 will melt as shown in FIG. Since it flows down from the surface, there is a problem that the surface of the fusible alloy 3 is oxidized and its operating temperature increases.

Therefore, the object of the present invention is to provide a method for manufacturing a temperature fuse in which the operating temperature does not change even if it is kept at a high temperature slightly lower than the operating temperature for a long time as described above. A process of fixing a fusible alloy between the tips of the lead wires, a process of performing low left processing on the surface of the fusible alloy to make the cross section uneven, and a process of applying flux to the back side of the fusible alloy. It is characterized by containing.

In other words, when an uneven surface is formed on the surface of the fusible alloy by the above-mentioned method, the oxide film formed on the surface of the fusible alloy in its natural state or when it is fixed to the lead wire is broken, and flux is not applied to the surface. During deposition, the flux accumulates in the concavities of the uneven surface due to surface tension, ensuring that the entire surface of the fusible alloy is covered with flux, and the temperature fuse is exposed to high temperatures slightly lower than the operating temperature for a long period of time, causing the flux to accumulate. Even if it melts, the molten flux will accumulate in the recess due to its surface tension, so the fusible alloy will not be exposed and its surface will be oxidized and the operating temperature will rise, providing a highly reliable temperature fuse. .

Takumi Shoko Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1(A) to F).

First, a cylindrical fusible alloy 3 is fixed between the tips of a pair of lead wires 1 and 2 by welding or the like (A). Next, the surface of the fusible alloy 3 is knurled. This knurling process not only forms an uneven surface 8 on the surface of the fusible alloy 3 (but also destroys the oxide film formed on the surface of the fusible alloy when left alone or when it is stuck to the lead wires 1 and 2). CB, C) where fresh fusible alloy is exposed. Next, a molten flux 4 is applied to the surface of the fusible alloy 3. At this time,
Uneven surface 8 where fresh fusible alloy is exposed on the surface of fusible alloy 3
is formed, so even if the flux 4 has a low viscosity, it can be easily and reliably applied to the entire surface (D, E). Next, this is inserted into the insulating case 5 and firmly sealed with sealing resins 6 and 7 (F).

According to this invention, since the surface of the fusible alloy is formed into an uneven surface and the flux is applied, even flux with low viscosity can be applied to the entire surface of the fusible alloy with a sufficient thickness. In particular, by forming an uneven surface after fixing the fusible alloy to the lead wire, the oxide film formed on the surface of the fusible alloy can be broken by leaving it naturally or by heating when the lead wire and the fusible alloy are fixed. This exposes a fresh surface of fusible alloy, ensuring flux retention. In addition, even if the temperature fuse is held at a high temperature slightly lower than the operating temperature for a long time and the flux melts, the molten flux will surely accumulate on the surface of the fusible alloy, and the surface of the fusible alloy will be exposed. A reliable temperature fuse can be manufactured whose surface will not be oxidized and its operating temperature will not increase.

[Brief explanation of the drawing]

FIGS. 1A to 1F are cross-sectional views at different stages for explaining a manufacturing method according to an embodiment of the present invention.
A) is after the lead wire and fusible alloy are fixed, (B) is after knurling on the surface of the fusible alloy, (C) is an enlarged cross-sectional view along the line C-C of (B), and (D) is the After the flux is applied to the molten alloy, (E) is an enlarged cross-sectional view along the E-E line in (D), and (F
) indicates the state after being sealed in an insulating case. FIG. 2 is a sectional view of a conventional temperature fuse, FIG. 3 is a sectional view after operation, and FIG. 4 is a sectional view of an undesirable state when maintaining a high temperature. 1.2...Lead wire, 3...Fusible alloy, 4...
・・・・・・Flux, 5・・・・・・・・・・・・
Insulating case, 6.7... Sealing resin, 8...... Uneven surface.

Claims (1)

[Claims] A method for manufacturing a thermal fuse, in which a fusible alloy is fixed between the tips of a pair of lead wires, the surface of the fusible alloy is coated with flux, and the fuse is sealed in an insulating case. (a) fixing a fusible alloy between the tips of a pair of lead wires; (b) knurling the surface of the fusible alloy to form an uneven surface; (c) 1. A method for manufacturing a thermal fuse, comprising the step of applying flux to the surface of a molten alloy.