JPH0576730B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a temperature fuse whose main components are a fusible metal and a flux, which are widely used to prevent overheating in various electronic devices. Structure of the conventional example and its problems A temperature fuse obtained by the conventional manufacturing method is shown in FIG. 1 and FIG. ,2'
After the thermoplastic resin 3 is applied to the outer periphery of the easily fusible metal 1, it is housed in an insulating case 4. Next, as shown in FIG. 1, the openings at both ends of the insulating case 4 are sealed with thermosetting insulating paint 5, 5'. The curing conditions for the thermosetting insulating coatings 5 and 5' include heating for a long time at a temperature lower than the operating temperature of the temperature fuse or lower than the softening point of the thermoplastic resin 3 coated on the outer periphery of the easily melted metal 1. It was not suitable for mass production because it had to be cured. Also,
Disadvantages: It is difficult to apply the appropriate amount of thermosetting insulating paint 5, 5' and the amount tends to vary, the holding force between the insulating case 4 and the terminal wires 2, 2' decreases, and mechanical strength and sealing strength vary. It had In FIG. 2, metal caps 6 and 6' having terminal wire insertion holes on the outer periphery of the opening at both ends of the insulating case 4 are connected to the terminal wires 2 and 6'.
After inserting 2' into the insertion hole and press-fitting it,
Connect terminal wires 2, 2' and metal caps 6, 6' to alloy 7,
After heating and welding in step 7', the outer periphery is sealed with insulating paint 5. Here, if the alloys 7 and 7' are melted at a temperature lower than the operating temperature of the temperature fuse, the metal caps 6 and 6' and the terminal wires 2 and 2' cannot be held together, so alloys that melt at a higher temperature than the easily fusible alloy 1 are 7, 7' must be used. Therefore, it takes a long time to heat the alloys 7 and 7' with a soldering iron, etc., and the heat can be applied to the easily fusible alloy 1, causing it to melt, making the heating conditions difficult, leading to variations in performance, and failures. The rate would also be higher. In addition, when the metal caps 6, 6' are inserted into the terminal wires 2, 2' and press-fitted into the insulating case 4, the terminal wires 2, 2'
If the metal caps 6, 6' and the insulating case 4 are bent, the centers of the metal caps 6, 6' and the insulating case 4 cannot be aligned, resulting in poor press-fitting. Purpose of the Invention The present invention has been made to address these conventional problems, and has excellent mass productivity, mechanical strength,
The object of the present invention is to provide a method for manufacturing a temperature fuse at a low cost that has uniform sealing strength and fusing performance. Structure of the Invention In order to achieve this object, the present invention covers the outer periphery of an easily fusible metal with a thermoplastic resin, houses the easily fusible metal part in an insulating case, and has a terminal wire,
A metal cap with a plated outer periphery is press-fitted and fixed to the outer periphery of the opening at both ends of the insulating case, and then the terminal wire or the metal cap part is chucked with a highly conductive metal chuck to supply current, thereby forming the metal cap having the terminal wire. By welding both ends of the above-mentioned easily fusible metal, it is possible to manufacture a temperature fuse that is excellent in mass production and has excellent mechanical strength, sealing strength, and fusing performance. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a sectional view of an embodiment of a temperature fuse obtained by the manufacturing method of the present invention. To manufacture it, first, a filamentous easily fusible metal 11 made of tin, lead, bismuth, indium, cadmium, or an alloy thereof is coated with a heat-softening resin 13 having flux and adhesive properties. The insulating case 14 is inserted through one opening of the insulating case 14 made of glass, ceramic, etc. and has openings at both ends, and the insulating case 14 is heated to the softening temperature of the thermoplastic resin 13.
to be fixed. Next, connect the terminal wires 12, 12',
Metal caps 15 and 15', which are made of iron, copper, etc. and plated with tin, lead, bismuth, indium, cadmium, copper, etc., or alloys thereof, are press-fitted and fixed onto the outer peripheries of openings at both ends of the insulating case 14. The inner diameter of these metal caps 15, 15' is the same as that of the insulating case 14.
The fixation strength after press-fitting will be stronger if the outer diameter is about 0.2 mm to 0.5 mm smaller than the outer diameter. Also, if the easily fusible metal 11 is about 0.2 mm to 2.0 mm longer than the total length of the insulating case 14, when the metal caps 15, 15' are press-fitted,
The state of bonding with the inner surfaces of the metal caps 15, 15' is good. The easily fusible metal 11 and metal caps 15, 15' press-fitted in this way are attached to a highly conductive metal cap 1 as shown in FIGS. 4 and 5.
6, 17 and 16', 17' terminal wire 12,
12' and metal chuck 16,
17 and 16', 17', the current instantly heats the terminal wires 12, 12' and the metal caps 15, 15', and the metal cap 1
5, 15' and both ends of the easily fusible metal 11 are formed with melting joint surfaces 18, 18'. Further, in order to maintain stable performance for a long period of time, the outer periphery of the temperature fuse is coated with an insulating paint 19. Temperature fuses made using this manufacturing method are
Because the easily fusible metal 11 and the terminal wires 12, 12' are not directly connected and are firmly fixed to the insulating case 14 by the metal caps 15, 15',
There is no deterioration in mechanical strength, and highly accurate and stable characteristics can be obtained. FIG. 6 shows a state in which the easily fusible metal 11 is slightly longer than the overall length of the insulating case 14. In addition, in the present invention, the metal cap 15, 15' portion is replaced with the metal chuck 16, 17.
And 16', 17' may be chucked and energized. Specific examples will be described below. First, melting point alloys made of tin, lead, and indium are easily melted.
126℃, wire diameter 0.7mmφ, length 8.0mm easily melted metal, insulating case is ceramic case with outer diameter 2.5mm, inner diameter 1.2mm, length 7.0mm, thermoplastic resin softening point 80℃, metal cap. The inner diameter was 2.45 mmφ, and the terminal wire diameter connected to the metal cap was 0.7 mmφ. and,
The terminal wire was chucked with a metal chuck, and a current of approximately 180 amperes was passed between the metal chucks for 6 cycles (60Hz commercial frequency). Next, an insulating paint was applied to the outer periphery and cured by heating at a high temperature of 115°C for 2 hours. The temperature fuse thus prepared was raised in silicone oil at a rate of 1° C./min and the melting temperature was measured, and the results shown in Table 1 below were obtained. Further, when one terminal wire was fixed and the other terminal wire was pulled and the tensile strength was measured, the results shown in Table 2 below were obtained. All of these properties were good.

【table】

[Table] Effects of the Invention As described above, according to the manufacturing method of the present invention, the easily fusible metal and the metal cap can be easily and stably welded, and the terminal wire and the easily fusible metal are not directly connected. Moreover, since it is firmly fixed to the insulating case by the metal cap, there is no deterioration in mechanical strength, and it is possible to manufacture products with high precision and stable performance through continuous production. In addition, since the terminal wire diameter can be changed regardless of the wire diameter of the easily fusible metal, it is possible to provide a wide variety of compact, inexpensive, and highly accurate temperature fuses, which is the purpose of this type of temperature fuse.
It is very effective.

[Brief explanation of the drawing]

1 and 2 are respectively sectional views of a conventional temperature fuse, FIG. 3 is a sectional view of an embodiment of a temperature fuse obtained by the manufacturing method of the present invention, and 4 and 5 are sectional views of a temperature fuse manufactured by the present invention. Fig. 6 is a cross-sectional view of a state in which a terminal wire according to the method is chucked with a metal chuck, and Fig. 6 is a cross-sectional view of a state in which an easily fusible metal longer than the insulating case is used in the manufacturing method of the present invention and current is passed through chucking. It is. 11...Easily fused metal, 12,12'...Terminal wire,
13...Thermosoftening resin, 14...Insulating case, 1
5, 15'...metal cap, 16, 16', 1
7,17'...Good conductive metal chuck.

Claims (1)

[Scope of Claims] 1. The outer periphery of the easily fusible metal is covered with a heat-softening resin having flux and adhesive properties, and the easily fusible metal part is housed in an insulating case having openings at both ends, and a terminal wire is provided. Then, a metal cap with a plated outer periphery is press-fitted and fixed to the outer periphery of the opening at both ends of the insulating case, and then the terminal wire or the metal cap portion is chucked with a highly conductive metal chuck to supply current, thereby forming the terminal wire. A method for manufacturing a temperature fuse, characterized by welding both ends of a metal cap and the above-mentioned easily fusible metal. 2. The method of manufacturing a temperature fuse according to claim 1, wherein the easily fusible metal is made longer than the overall length of the insulating case and housed in the insulating case.