JPH06251675A - Joining method of rod-like part - Google Patents

Abstract

PURPOSE:To prevent a joining part from becoming narrow and improve the mechanical strength of the part wherein the joining part is formed by coaxially welding two rod-like parts such as a thermal fuse of a fusable alloy and a lead wire. CONSTITUTION:In the case of coaxially welding a joining end part 1a of a fusable alloy 1 of a thermal fuse with a joining end part 2a of a lead wire 2, the joining end part 1a of the fusable alloy 1 is previously bent almost rectangularly. The bent end part 1b which is so formed as to become a thicker end of the fusable alloy is partly melted by laser light 4 and welded to the joining end part 2a of the lead wire 2, so that the joining part 3 of the fusable alloy 1 and the lead wire 2 are formed to be thick and thus the mechanical strength of the joining part 3 is stabilized constantly. Besides the method to thicken the joining end part 1a of the fusable alloy 1, it is possible to employ a method to form the joining end part 1a as a spherical end part by heating the part to melt and then solidifying the molten end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining rod-shaped members in which end faces of a pair of metal rod-shaped members are butted against each other and welded coaxially.

[0002]

2. Description of the Related Art As an example of a product having a pair of coaxially welded rod-shaped members, the structure and manufacturing method of a fusible alloy type thermal fuse (5) shown in FIG. 4 will be described.

The thermal fuse (5) is formed by welding lead wires (2) coaxially to both ends of a rod-shaped fusible alloy (1) and applying flux (6) to the fusible alloy (1). It is inserted in a cylindrical insulating case (7) such as ceramic, and the fusible alloy (1) is arranged in the center of the insulating case (7). The open end of the insulating case (7) and the lead wire ( The space between 2) is sealed with resin (8).

The thermal fuse (5) is attached near the heat generating portion of a set device (not shown) and is connected to a device protection circuit of the set device. When the temperature of the set device abnormally rises, the fusible alloy (1) of the thermal fuse (5) is melted and spherically condensed at the joint ends of the pair of lead wires (2) to open the space between the lead wires. Protect equipment.

The fusible alloy (1) and the lead wire (2) are rod-shaped members having substantially the same wire diameter, and both are coaxially welded with their end faces abutting each other. The joining of the pair of rod-shaped members is performed in the manner shown in FIGS. First, as shown in Fig. 5 (a), the straight round rod-shaped fusible alloy (1) and the lead wire (2) are made to have their joint end surfaces coaxially close to each other. The part is locally heated by the heating means (9) of the discharge arch or gas burner to melt it.
When the melted joint end of the fusible alloy (1) and the joint end of the lead wire (2) are butted against each other, the melted joint end of the fusible alloy (1) becomes a lead wire as shown in FIG. 5 (b). It wraps around and welds to the joint end surface of (2).

[0006]

When the fusible alloy (1) of the thermal fuse (5) and the pair of rod-shaped members such as the lead wire (2) are joined in the above manner, the joint ends of the pair of rod-shaped members are joined together. If the joint form before welding is poor, the joint strength of the joint portions of both rod-shaped members may become extremely weak. For example, in the case of the fusible alloy (1) and the lead wire (2), as shown in FIG. 6 (a), a misalignment occurs between the joint end faces of the fusible alloy (1) and the lead wire (2). As shown in FIG. 6 (b), if one of the two rod-shaped members, for example, the joint end face of the fusible alloy (1) is inclined, the joint end of the fusible alloy (1) becomes a lead wire ( As shown in Fig.
As shown in (c), a thin portion (m) may occur at the joint portion (3 ′) of both rod-shaped members.

[0007] Such a thin portion (m) of the joint (3 ')
Is often referred to as thinness and often becomes a defective portion that weakens mechanical strength such as bending resistance of the joint portion (3 ′). In the thermal fuse (5), the fusible alloy (1) and the lead wire (2) are coaxially welded, and then the joint (3 ') is subjected to a 180 ° bending test. ) Thin part (m)
If there is, the joint (3 ') is broken from the thin portion (m) during the bending test, and the product fails. In fact, the bending test pass rate of the welded fusible alloy (1) and the lead wire (2) is currently as low as about 30% due to the occurrence of the thin portion (m).

Therefore, the object of the present invention is to
It is an object of the present invention to provide a rod-shaped member joining method capable of always welding a pair of rod-shaped members such as a fusible alloy of a thermal fuse and a lead wire with a highly stable joining strength.

[0009]

According to the present invention, when the end faces of a pair of metal rod-shaped members are coaxially joined, at least one joint end of the pair of rod-shaped members is enlarged in the radial direction, The expansion molding joint end is locally heated and welded to the joint end of another rod-shaped member to achieve the above object.

The expansion-molded joint end of the rod-shaped member is a bent end formed by bending the end of the rod-shaped member at a substantially right angle or a metal block obtained by locally heating and melting the end of the rod-shaped member. A spherical end is desirable.

Further, if one of the pair of rod-shaped members is a fusible alloy having a lower melting point than the other, and the welding end of the fusible alloy is used as the expansion-molding joining end, the other rod-shaped member is welded to the temperature fuse. The fusible alloy and the two rod-shaped members such as the lead wire are securely joined.

Further, the local heating of the enlarged molding joining end portion of the rod-shaped member is advantageous in that a heating method using a laser beam allows easy fine adjustment of the amount of heat.

[0013]

When at least one of the pair of rod-shaped members has a large-diameter expansion-molding joining end and the expansion-molding joining end is locally heated and welded to the joining end of the other rod-shaped member,
The excess-thickness-enlarged portion of the molten metal at the end of the expansion-molded joint forms a thick joint at the two rod-shaped members, and the mechanical joint strength of the joint is always high.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the present invention will be described with reference to FIGS.

The pair of rod-shaped members shown in FIG. 1 are the fusible alloy (1) and the lead wire (2) of the thermal fuse (5) of FIG. When the fusible alloy (1) and the lead wire (2) are coaxially joined to each other, in the method of the present invention, the joining end portion (1a) of the fusible alloy (1) is previously expanded in the radial direction. Then, the expansion molding joint end (1a) is butted against the joint end (2a) of the straight lead wire (2) and welded.

The expansion-molded joint end portion (1a) of the fusible alloy (1) before joining shown in FIG. 1 (a) is formed by bending the joint end portion of the straight fusible alloy (1) at a substantially right angle. Bent end (1
b). Bring the bent end (1b) close to the straight joint end (2a) of the lead wire (2) to form the fusible alloy (1).
And lead wire (2) coaxially. When the bent end (1b) of the fusible alloy (1) is locally heated and melted in the state of FIG. 1 (a), and the lead wire (2) is brought close to the fusible alloy (1),
The molten metal at the bent end (1b) wraps around to the joint end (2a) of the lead wire (2), and the fusible alloy (1) and the lead wire (2) are separated as shown in FIG. 1 (b). Welded.

When the bent end (1b) of the fusible alloy (1), which has been expanded and shaped, is heated and melted, the amount of molten metal is the same as that of the straight end without the bent end (1b). More than this amount, this excess molten metal is
Around the outer circumference of a), the joint portion (3) between the fusible alloy (1) and the lead wire (2) is formed to be sufficiently thick. Therefore, even if the fusible alloy (1) and the lead wire (2) are misaligned before joining, there is no concern that an unintentional thin portion (thinness) will occur in the joining portion (3), and the joining portion ( 3) Mechanical strength is highly stable.

The bending length of the bent end portion (1b) of the fusible alloy (1) that has been enlarged is a value within which the outer diameter of the joint portion (3) welded to the lead wire (2) is within an allowable range. Is set to. That is, when manufacturing the thermal fuse (5) of FIG. 4 with the fusible alloy (1) and the lead wire (2), the outer diameter of the joint (3) between the fusible alloy (1) and the lead wire (2) is When it gets bigger than necessary,
This may adversely affect the operating characteristics of the thermal fuse (5). Therefore, the bending length and volume of the bent end portion (1b) are determined within an appropriate range so that the outer diameter of the joint portion (3) does not exceed its upper limit value.

The laser light (4) shown in FIG. 1 (a) is suitable and desirable as the heating means for locally heating the bent end (1b) of the fusible alloy (1) which has been expanded and shaped. That is,
The fusible alloy (1) in the thermal fuse (5) has various types with different melting points, and the heating means for locally heating the bent end (1b) of the fusible alloy (1) is adapted to the melting point of the fusible alloy (1). A laser beam (4) that can accurately and easily adjust the amount of heat is appropriate. Further, the laser beam (4) has an advantage of irradiating only the bent end portion (1b) of the fusible alloy (1) from an arbitrary direction and locally heating at high speed to a predetermined temperature efficiently.

The fusible alloy (1) shown in FIG. 2 (a) is
The expansion molding joining end (1a) is a spherical end (1c). This spherical end (1c) is shown in FIG.
As shown in (a) and (b), the end portion of the fusible alloy (1) is a metal block that is locally heated by, for example, a laser beam (4) to be melted and hardened.

As shown in FIG. 2 (a), the fusible alloy (1)
The fusible alloy (1) and the lead wire (2) are coaxially arranged so that the spherical end (1c) of the lead wire (2) is brought close to the joining end (2a) of the lead wire (2). A laser beam (4) is locally heated to melt the fusible alloy (1) and the lead wire (2). Then, the molten metal at the spherical end (1c) wraps around to the joint end (2a) of the lead wire (2), and the fusible alloy (1) and the lead wire (2) as shown in FIG. 2 (b). Are welded.

Also in the case of FIG. 2, the amount of molten metal in the expanded spherical end (1c) of the fusible alloy (1) is larger than the amount of molten metal in the straight end without the bent end (1b). And the surplus wraps around the outer periphery of the joining end (2a) of the lead wire (2), and joins the fusible alloy (1) and the lead wire (2) (3).
To be thick enough. As a result, the undesired thin portion [thinness] at the joint (3) between the fusible alloy (1) and the lead wire (2)
There is no concern about the occurrence of cracks and the mechanical strength of the joint (3) is improved.

The present invention can be applied not only to the method of joining the fusible alloy and the lead wire in the fusible alloy type thermal fuse but also to the joining of two rod-shaped members made of the same material or different materials. Depending on the material and type of the above, it is possible to change the embodiment such that both joint ends of the two rod-shaped members are enlarged molding joint ends.

[0024]

According to the present invention, at least one of the pair of rod-shaped members is locally heated and welded to the joint end of the other rod-shaped member. The thick surplus forms a thick joint at the two rod-shaped members, and the mechanical strength of the joint is highly stabilized, and the non-defective rate of products in which the two rod-shaped members are coaxially joined can be improved. Has the effect of

Further, when the pair of rod-shaped members are the fusible alloy and the lead wire of the fusible alloy type thermal fuse, the fusible alloy and the lead wire can be satisfactorily connected without affecting the operation characteristics of the thermal fuse. As a result, the characteristics of the thermal fuse can be stabilized and the manufacturing yield can be improved.

Further, by locally heating the expansion molding joining end of the rod-shaped member with laser light and laser welding it to another rod-shaped member, the amount of heat at the time of locally heating the expansion molding joining end of the rod-shaped member can be adjusted by laser. By adjusting the intensity of light, you can do it easily, accurately, and with high efficiency. In particular, if the expansion molding joint end part formed in the fusible alloy type thermal fuse is locally heated by laser light, it becomes easy to locally heat the fusible alloy at the optimum temperature adapted to its melting point. Excellent in improving quality and yield.

[Brief description of drawings]

1 illustrates a first embodiment of the present invention,
(A) is a side view of the rod-shaped member immediately before joining, (b) is a side view of the rod-shaped member after joining

FIG. 2 illustrates a second embodiment of the present invention.
(A) is a side view of the rod-shaped member immediately before joining, (b) is a side view of the rod-shaped member after joining

3 shows an example of processing one rod-shaped member of FIG.
(A) is a side view of the bar-shaped member immediately before processing, (b) is a side view of the bar-shaped member after processing

FIG. 4 is a sectional view of a fusible alloy type thermal fuse having two rod-shaped members to be joined.

5A is a side view immediately before joining the fusible alloy, which is the two rod-shaped members used in the thermal fuse of FIG. 4, and the lead wire, and FIG. 5B is the fusible alloy and lead wire of FIG. 4A. Side view after joining

6 (a) and 6 (b) are side views showing examples of morphological defects immediately before joining the fusible alloy of FIG. 5 (a) and the lead wire, and FIG. 6 (c) is the fusible alloy of FIG. 5 (b). Side view showing an example of defective lead wire connection

[Explanation of symbols]

 1 Rod-shaped member [Fusable alloy] 1a Expanded joint end 1b Bent end 1c Spherical end 2 Rod-shaped member [Lead wire] 2a Joint end 3 Joint 4 Laser light

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01H 85/143

Claims (5)

[Claims] 1. When the end portions of a pair of metal rod-shaped members are coaxially joined, at least one joint end portion of the pair of rod-shaped members is enlarged and formed in the radial direction, and the enlarged and formed joint ends are formed. A method for joining rod-shaped members, which comprises locally heating and welding the joint end portion of another rod-shaped member. 2. The joining method for a rod-shaped member according to claim 1, wherein the expansion molding joining end of the rod-shaped member is a bent end formed by bending the end of the rod-shaped member at a substantially right angle. 3. The method for joining rod-shaped members according to claim 1, wherein the expansion-molding joining end portion of the rod-shaped member is a spherical end portion obtained by locally heating, melting and hardening the end portion of the rod-shaped member. 4. The rod-shaped member according to claim 1, wherein one of the pair of rod-shaped members is a fusible alloy having a lower melting point than the other, and the joint end of the fusible alloy is an expansion-molded joint end. Joining method. 5. The expansion molding joining end portion of the rod-shaped member is locally heated by laser light to be melted and welded to the joining end portion of another rod-shaped member. Method for joining rod-shaped members.