JPH079125A - Heating element for heat transfer brazing - Google Patents

Abstract

(57) [Summary] [Structure] For heat transfer brazing, in which the brazing material 11 having a lower melting point than that of the members to be joined is melted by heat conduction mainly by contact with the members to be joined 10 A bottom wall portion 2 having a thickness of 10 mm or less, which is a heating element and has an outer surface serving as a contact heating surface 2a for a member to be joined, and a side wall portion 3 formed in a rising shape on the periphery of the bottom wall portion 2. It has a cylindrical heating head 1 and a heat source 4 for heating the bottom wall portion of the heating head 1. [Effect] The heat from the heat source can be directly applied to the bottom wall portion, and the applied heat can be efficiently conducted to the members to be joined. Since the side wall portion can prevent the heat of the inner hollow portion of the heating head from being diffused into the atmosphere, the inner hollow portion of the heating head can be constantly maintained at a high temperature. As a result, the temperature of the contact heating surface of the heating head during brazing can be prevented from lowering, and brazing can be performed in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating element for heat transfer brazing used for joining members to be joined made of metal such as aluminum (including its alloy).

[0002]

2. Description of the Related Art For example, as a joining method for partially joining aluminum materials, copper and other electrodes are placed in contact with members to be joined which are placed in a superposed state at a predetermined joining position, and the members to be joined are pressed under pressure. BACKGROUND ART Resistance spot welding is performed in which an electric current is applied to a predetermined joining portion, and resistance heating due to the electric current raises the temperature of the joining portion to perform welding. In addition, brazing in the atmosphere such as torch brazing and high frequency brazing is also performed.

However, in the above resistance spot welding method, since the specific resistance of the aluminum material is small,
There are drawbacks such that a large current is required to obtain the amount of heat required for welding and that the electrode dressing interval is shortened because an alloy of copper and aluminum is easily formed at the electrode tip. On the other hand, in the torch brazing method and the high frequency brazing method, it is physically difficult to perform heating and pressurizing at the same time. It had the drawback of being long.

Therefore, as an alternative joining method, a brazing material having a lower melting point than that of the members to be joined is interposed at the joining interface, and the heating element is brought into contact with the members to be joined under pressure.
A heat transfer brazing method has been developed in which the brazing filler metal is melted mainly by heat conduction from the heating element, and thus both members to be joined are joined. According to this method, it is possible to easily bond a wide range of parts in the atmosphere, the energy cost is low, and it is possible to bond parts to which spot welding or the like cannot be applied, so that the degree of freedom in bonding can be dramatically improved. There are advantages.

As a heating element used for such heat transfer brazing, conventionally, as shown in FIG. 4, the heating head (2
0) was formed in blocks by steel slabs, graphite and other substances. Then, the two block-shaped heating heads (20) (20) are heated in advance, and their contact heating surfaces (20a) (20a) are bonded to the members (10) (10) during brazing. The joint was heated by contacting it under pressure. In FIG. 4, (11) is a brazing filler metal which is interposed between the joint portions (10a) (10a) of the upper and lower joint members (10) (10).

[0006]

However, in the heating element having the block-shaped heating head (20) as described above, particularly when the joined member (10) is aluminum or the like having a large heat capacity per unit volume. Heads for heating (20)
Since the amount of heat transfer inside the heating head (20) cannot catch up with the amount of heat transfer from the contact heating surface (20a) to the joined member (10), the heating head (20) There was a drawback that the temperature of the contact heating surface (20a) decreased. Therefore, it takes time for the brazing material (11) to melt, and it is difficult to perform brazing in a short time, resulting in poor productivity.

The present invention has been made in view of the above technical background, and an object thereof is to provide a heat transfer brazing heating element capable of shortening the brazing time.

[0008]

In order to achieve the above object, according to the present invention, the heating head is not formed in the shape of a block, but is formed in a cylindrical shape having a thin tip contact portion. is there.

More specifically, referring to the reference numerals in the drawings, the brazing filler metal (11) having a lower melting point than that of the members to be joined is melted mainly by heat conduction caused by contact with the members (10) to be joined. A heating element for heat transfer brazing for joining members to be joined (10), a bottom wall portion (2) having an outer surface serving as a contact heating surface (2a) to the members to be joined and having a thickness of 10 mm or less; A cylindrical heating head (1) having a side wall portion (3) formed in a rising shape on the periphery of the bottom wall portion (2), and the bottom wall portion (2) of the heating head (1). ) Is provided with a heat source (4) for heating heat transfer brazing.

In the above description, "mainly" does not require that all the heat be transferred by contact, but allows a part of the heat to be transferred by radiation or convection.

[0011]

Function: The heat from the heat source (4) is directly applied to the bottom wall (2), and the applied heat is efficiently supplied to the members to be joined (1).
0) is transmitted. Further, the side wall portion (3) of the heating head (1) prevents the heat in the inner hollow portion of the heating head (1) from being diffused into the atmosphere.

[0012]

1 and 2 showing an embodiment of the present invention, (1) is a heating head and (4) is a heat source.

The heating head (1) has a bottom wall (2).
And a tapered side wall portion (3) rising outwardly in a slanting manner on the peripheral edge of the bottom wall portion (2) to form an outer opening tubular shape with an upper end opening. In addition, the bottom wall portion (2) plays a role of receiving heat from the heat source (4) and contacting the members to be joined during brazing to heat the joint portion, and the outer surface thereof has a flat shape. It is designed as a contact heating surface (2a). Further, the wall thickness t of the bottom wall portion (2) is set to 10 mm or less, preferably 5 mm or less in order to ensure good heat conduction. On the other hand, the side wall portion (3) serves to prevent the heat in the inner hollow portion of the heating head (1) from diffusing into the atmosphere and confine the heat in the inner hollow portion of the heating head (1). .

The material of the heating head (1) is not limited, and may be appropriately selected and used from SUS, Inconel, ceramics and the like having good heat resistance, but especially heat conductivity, heat resistance and the like. It is preferable to use excellent ceramics. Examples of ceramics include AlN and Si
₃ N ₄ , BeO, BN, Al ₂ O ₃ , MgO, SiC,
Mullite, graphite, diamond and the like may be mentioned.

The heat source (4) directly heats the bottom wall portion (2) of the heating head (1), and the bottom wall portion (2).
It is desirable to provide a heat flux as large as possible (for example, about 1 × 10 ⁶ W / m ² or more). Speaking of heating methods, burner heating, laser heating, infrared heating and the like are desirable. In this embodiment, a butane burner is used as the heat source (4).

An example of the heat transfer brazing method using the heating element shown in FIGS. 1 and 2 is as follows.

That is, first, as shown in FIG. 3, the melting point is lower than that of the joined members between the joined portions (10a) (10a) of the two joined members (10) (10) made of aluminum or the like. The brazing material (11) is arranged in an intervening state. The joint (10a
) (10a) is supplied with flux as needed. The flux may be applied to the surface of the brazing filler metal (11), but in a preferred embodiment, it is preferable to use a flux-containing brazing filler metal that does not require flux application. As an example of the flux-containing brazing filler metal, a powder of an Al alloy containing an element such as Si or Zn, or a powder of a simple substance of these component elements is mixed with a fluoride-based flux or a chloride-based flux. An example thereof is a mixture of the powder mixture that has been hot pressed and then molded into a desired shape by extrusion molding or the like. Further, as a typical composition of such a solid brazing material, A
1, Si, 3 to 15 wt% of Si based on the total content of metal components excluding fluoride flux, the total of elements excluding fluoride flux and fluoride flux. In a weight ratio of 99.9: 0.1-7
The content may be 0:30 and the density is 90% or more of the theoretical value. Further, as the brazing material, a material obtained by mixing and stirring a liquid binder with the above alloy powder or a single powder of the alloy composition and flux powder may be used.

Next, the two members to be joined (10) (10) with the brazing filler metal (11) interposed therebetween are arranged above and below the two members to be heated in advance. In each heating element, the bottom wall portions (2) and (2) of the heating heads (1) and (1) are connected to the joined member (1).
0) side. Then, at the position of the joining portion, the bottom wall portion (2) of the upper heating head (1) is connected to the upper joined member (10) and the bottom wall portion (2) of the lower heating head (1) is attached. The lower members (10) to be joined are brought into contact with each other and pressed.

Contact heating surface (2a) of the bottom wall (2) (2)
When (2a) contacts the members (10) (10) to be joined, the heat from the bottom wall (2) heated by the butane burner which is the heat source (4) is conducted to the members (10) to be joined. Further, it is conducted to the brazing material (11). Bottom wall (2) has a wall thickness of 10
Since the thickness is less than or equal to mm, the bottom wall portion (2) has a small thermal resistance and therefore does not hinder heat conduction, and the heat from the heat source (4) is efficiently conducted to the joined member (10). Moreover, the presence of the side wall portion (3) suppresses the diffusion of heat in the inner hollow portion of the heating head (1) into the atmosphere, and traps high-temperature heat in the inner hollow portion of the heating head (1). As a result, a large amount of heat is efficiently conducted to the joined members (10).

By the heat conduction from the heating element, the brazing material (11)
Is melted in a short time and both members (10) (10) to be joined are joined.

Incidentally, in order to confirm the effect of the heating element according to the present invention, the following test was conducted. First, two heating elements below were prepared.

As shown in FIG. 3, the heating element (outer diameter of the bottom wall portion (2) according to the present invention, in which the heat source (4) made of butane burner is arranged in the cylindrical heating head (1) made of SUS304. φ1: 30 mm, outer diameter of open end φ2: 80 mm,
Thickness t of bottom wall (2) and side wall (3): 5 mm, length L1 of heating head (1): 100 mm, heat flux applied to bottom wall (1) of about 2.0 × 10 ⁶ W /
m ² ).

As shown in FIG. 4, a conventional heating element having a block-shaped heating head (20) made of SUS304 that is heated by an electrothermal heating method (the diameter of the heating head (20) is φ3: 30 mm, and the length is 30 mm). L2: 100 mm, heat flux applied to the heating head (20) about 0.7 × 10 ⁶ W /
m ² ).

On the other hand, as a member to be joined (10), A300
Thick 1mm x width 30mm x length 100m consisting of 3 alloys
Two aluminum plates of m were prepared, and an Al—Si brazing filler metal (11) containing flux was arranged between the joined parts of these aluminum plates. The flux-containing brazing filler metal (11) was prepared by using Al-10 wt% Si alloy powder and fluoride-based flux (45.8% KF-54.2% AlF).
Eutectic powder of ₃ ) powder is mixed in a weight ratio of 80:20,
This mixed powder was thermocompressed and then molded into a size of 20 mm in length and width and 1 mm in thickness.

Next, as shown in FIGS. 3 and 4, two heating elements are arranged above and below with the members to be joined (10) (10) sandwiched therebetween, and all the heating elements are brought into contact with each other. The temperature of the heating surface (2a) (2a) (20a) (20a) is 1000 ℃
Then, the members to be joined (10) and (10) were brought into contact with each other under pressure, the brazing material (11) was melted, and both members to be joined were joined.
Then, when the time required for joining each heating element, that is, the contact time of the heating heads (1) (20) to the joined member (10) was examined, it took 60 seconds for the conventional product,
It was 20 seconds in this embodiment product.

Therefore, according to the present invention, it was confirmed that brazing can be performed in a short time.

In the above embodiment, the two heating elements are brought into contact with each other with the joining portion sandwiched therebetween, but the heating elements may be brought into contact with only one side of the joining portion.

[0028]

As described above, according to the present invention, the heating head has a wall thickness 1 whose outer surface is a contact heating surface for the members to be joined.
Since it is formed in a cylindrical shape having a bottom wall portion of 0 mm or less and a side wall portion formed in a rising shape on the peripheral edge of the bottom wall portion, heat from a heat source is directly applied to the bottom wall portion. In addition, the applied heat can be efficiently conducted to the members to be joined. Moreover, the side wall portion of the heating head can prevent the heat in the inner hollow portion of the heating head from being diffused into the atmosphere, so that the inner hollow portion of the heating head can always be maintained at a high temperature. As a result, sufficient heat equal to or more than the amount of heat that diffuses from the contact heating surface of the heating head to the joined member can be applied to the heating head,
It is possible to prevent a decrease in temperature of the contact heating surface of the heating head during brazing, and braze in a short time.

[Brief description of drawings]

FIG. 1A is a vertical sectional view of a heating element according to an embodiment of the present invention, and FIG. 1B is a bottom view.

FIG. 2 is a perspective view of the heating element of FIG.

FIG. 3 is a front cross-sectional view showing a state in which heat transfer brazing is performed using the heating element of FIGS.

FIG. 4 is a front sectional view showing a state where heat transfer brazing is performed using a conventional heating element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Heating head 2 ... Bottom wall 2a ... Contact heating surface 3 ... Side wall 4 ... Heat source 10 ... Joined member 11 ... Brazing material

Claims (1)

[Claims] 1. A brazing filler metal (1) having a melting point lower than that of the members to be joined (1) by heat conduction mainly by contact with the members (10) to be joined.
A heating element for heat transfer brazing that fuses 1) to join members to be joined (10), the bottom having a thickness of 10 mm or less with an outer surface serving as a contact heating surface (2a) to the members to be joined. A cylindrical heating head (1) having a wall portion (2) and a side wall portion (3) formed in a rising shape on the peripheral edge of the bottom wall portion (2), and the heating head (1) A heating element for heat transfer brazing, comprising a heat source (4) for heating the bottom wall portion (2).