JPH079124A - Heating element for heat transmission brazing - Google Patents

Abstract

PURPOSE:To efficiently conduct the heat from a heat source to members to be joined by forming a heating section of ceramics having excellent heat conductivity, insulation characteristic and heat resistance. CONSTITUTION:The heating section 2 is formed of the nonconductive ceramics. The heat from the heat source 4 is efficiently conducted via the heating section 2 to the members to be joined by the high thermal conductivity of the ceramics. Since the ceramics has the electrical insulating characteristic, there is no need for interposing an insulating material between the heating section 2 and the heat source 4. Since the direct contact of the heat source with the heating section is possible, the heat from the heat source 4 is efficiently conducted to the heating section 2 and an increase in heat resistance by the intervention of the insulating material is averted. The ceramics has the excellent heat resistance and, therefore, the deterioration of the heating section does not arise even if the ceramics comes into contact with a molten brazing filler metal.

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, a wide range of parts can be easily joined in the atmosphere, the energy cost is low, and it is possible to join parts such as hollow materials that cannot be spot-welded. There is an advantage that it can be improved.

The above-mentioned heating element used for such heat transfer brazing comprises a heat source and a heating section for receiving heat from the heat source. By bringing the heating section into contact with the members to be joined, It is said that the heat of is supplied to the joint.

A heating wire such as an electric heating wire is generally used as a heat source of the heating element, while a material for the heating portion is
Conventionally, heat-resistant alloys such as Inconel, Incoloy, Hastelloy, and Nimonic have been used in terms of workability, heat resistance, strength, and the like.

[0007]

However, when the heating portion is made of the heat-resistant alloy as described above, there are the following drawbacks.

That is, in the heat transfer brazing method, particularly when the members to be joined are aluminum or the like having a large heat capacity per volume,
In order to complete the brazing in a short time, it is necessary to supply heat from the heating section to the members to be joined at a very high heat flux via the contact surface. For this purpose, the heat of the heat source must be efficiently conducted to the members to be joined. However, the heat-resistant alloys described above generally have poor heat conduction efficiency, and the heating portion rather becomes a thermal resistance and becomes a member to be joined from the heat source. Brazing could not be completed in a short time because it hindered heat conduction to the.

Moreover, since Inconel is a conductive material, an insulating material such as magnesia powder must be interposed between the heat source and the heating section in order to avoid direct contact between the heating wire as the heat source and the heating section. Not only that, the structure becomes complicated,
The insulating material has a drawback that thermal resistance increases more and more.

The present invention has been made in view of the above technical background, and reduces the thermal resistance between the heat source and the member to be joined so that the heat from the heat source is efficiently conducted to the member to be joined. The object is to provide a heat transfer element capable of heat transfer brazing.

[0011]

In order to achieve the above object, the present invention has a high heat conductivity, high electric insulation and excellent heat resistance, instead of a heat resistant alloy such as Inconel as a material for a heating section. To use the ceramics.

[0012] That is, the present invention, as shown with reference to the drawings, comprises a heat source (4) and a heating part (2) for receiving heat from the heat source, and the heating part (2) is to be joined. Due to heat conduction mainly due to contact with the member (10), the brazing material (11) having a lower melting point than that of the members to be joined is melted and the members (10) (1)
The heating element for heat transfer brazing for joining according to claim 0), wherein the heating part (2) is formed of non-conductive ceramics. To do.

In the above, "mainly" means that it is not necessary that all the heat be transferred by contact, and that a part of the heat is transferred by radiation or convection.

[0014]

[Function] Due to the high thermal conductivity of ceramics, the heat from the heat source (4) is efficiently conducted to the members (10) to be joined via the heating section (2). In addition, since the ceramic has electrical insulation, it is not necessary to interpose an insulating material between the heating part (2) and the heat source (4), and the heat source can be brought into direct contact with the heating part. The heat can be conducted to the heating portion without waste, and the heat resistance is not increased due to the interposition of the insulating material. In addition, since ceramics have excellent heat resistance, the heated portion does not deteriorate due to contact with the molten brazing material.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. In this embodiment, a square heat insulating base (1) made of SS304 material and a cylindrical heating element (2) provided in a hanging state at the center of the lower surface of the base (1) have a T shape in a front view. The formed heating element is shown.

The heating part (2) has a hollow part (3) for inserting a cartridge heater therein, and the hollow part (3).
A heat source (4) composed of a cartridge heater is closely inserted into the. A flat contact surface (21) is formed at the center of the lower surface of the heating section (2), and a tapered heat radiation surface (22) is provided around the contact surface (21). is doing.

In the present invention, the heating part (2) is required to be formed of ceramics. The reason for this is that ceramics have a high thermal conductivity, and the heat from the heat source (4) can be efficiently conducted to the members to be joined via the heating section (2). Moreover, since it has electric insulation, it is not necessary to interpose an insulating material between the heating part (2) and the heat source even when a heating wire is used as the heat source. Further, it is also excellent in heat resistance and has high durability without being deteriorated by touching the molten brazing filler metal. The type of ceramics is not particularly limited as long as it can be processed into the desired shape of the heating part (2), but preferably has a thermal conductivity of 50 W / (m · K) or more or a thermal diffusivity of 20 mm. ² / S or more is preferable. For example, AlN,
Si ₃ N ₄ , BeO, BN, Al ₂ O ₃ , MgO, Si
C, mullite, graphite, diamond and the like may be mentioned. Particularly, AlN is preferable.

The heat source (4) consisting of the cartridge heater has a heating wire spirally wound in an Inconel sheath, and magnesia powder as an insulating material is provided in a space other than the heating wire. It is filled. Of course, the sheath of the cartridge heater may also be formed of ceramics so that the internal insulating material is unnecessary. Further, the heat source (4) is not limited to the cartridge heater, and the heating wire may be directly housed and arranged in the heating section (2).

Incidentally, (5) shown in FIG. 1 is a lead portion through which the lead wire connected to the heating wire of the cartridge heater (4) passes.

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

That is, first, as shown in FIG. 2, 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 members to be joined (10) (10) with the brazing material (11) interposed therebetween are placed on a support base (12) made of a heat insulating material such as rock wool, and the heat source (4) is preliminarily set. The heating element that heats the heating part (2) by heating the
) Is arranged such that the contact heating surface (31) is in contact with the upper joined member, and a pressing force in the pressing direction is applied to the joining portion (10a) via the heating portion (2).

When the contact surface (21) abuts on the upper joined member (10), the upper joined member (10) from the contact surface (21).
Is conducted to the brazing filler metal (11). Since the heating part (2) is made of ceramics, the thermal conductivity of the heating part is high, and therefore the heat received from the heat source (4) to the heating part (2) is efficiently transferred to the contact surface (21). Good conduction, and further, efficient conduction from the contact surface (21) to the members to be joined. At the same time, heat radiation is performed from the heat radiation surface (22) around the contact surface (21) to the upper joined member, and the periphery of the joining portion (10a) is heated, so that the contact surface (21).
It is possible to prevent the heat conducted from the to the upper joined member from being diffused to the surroundings.

As described above, heat is efficiently supplied from the contact surface (21) and the heat radiation surface (22) to the joint portion (10a) and its periphery, and the brazing filler metal (11) is melted in a short time. The members to be joined (10) (10) are joined.

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

In the heating element shown in FIG. 1, the heating part (2) is formed of AlN ("Shapal M" manufactured by Tokuyama Soda Co., Ltd., thermal conductivity: about 100 W / (mK)). The cartridge heater as the heat source (4) is 500 W, and the outer diameter φ1 of the heating part (2) is 40 m.
m, and the diameter φ2 of the tip contact surface (21) was 20 mm.

The heating section (2) is formed of Inconel 600, and the cartridge heater is set to 1.8 KW.
The same conventional heating element as above except that the outer diameter of the heating portion was 50 mm.

The same conventional heating element as described above except that the heating part (2) is made of copper and the cartridge heater is 1.2 kW.

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,
After thermocompression molding this mixed powder, length and width 20mm, thickness 0.7mm
The one molded into was used.

Next, after the above-mentioned members to be joined are placed on the heat insulating support (12) as shown in FIG. 2, and for the heating element (1), the temperature of the heating part (2) is set to 1000 ° C. Was set to 700 ° C. and brought into pressure contact with the upper joined member (10) with a pressing force of 10 kgf, and the brazing material (11) was melted to join both joined members. When the time required for joining each heating element, that is, the contact time of the heating element with the member to be joined until the brazing is completed was examined, it took 90 seconds for the heating element and 120 seconds for the heating element. It was 40 seconds in the product of the present invention.

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

The shape of the heating part (2) of the heating element is not limited to that shown in the illustrated embodiment. Further, although the heating element is contacted only from one side of the joint (10a), the heating elements may be contacted from both sides with the joint in between.

[0033]

The heating element for heat transfer brazing according to the present invention is
Depending on the above, since the heating part that receives the heat from the heat source is made of ceramics, the high thermal conductivity of the ceramics allows the heat from the heat source to be efficiently conducted to the joined members through the heating part. Therefore, brazing can be completed in a short time, and productivity can be improved and power consumption can be reduced.

Further, since the ceramic has electric insulation, it is not necessary to interpose an insulating material between the heating part and the heat source, and the heat source can be brought into direct contact with the heating part. Therefore, the heat from the heat source is wasted. Since the heat can be conducted to the heating portion without causing an increase in the thermal resistance due to the interposition of the insulating material, the heat of the heat source can be conducted to the joined members via the heating portion more efficiently.

Further, since ceramics are also excellent in heat resistance, they can be used as a heating element capable of performing a stable heating operation for a long period without touching the molten brazing filler metal to deteriorate the heating part.

Further, since the molten brazing material and the ceramics are generally not wet, the molten brazing material does not adhere to the heating portion and the heating surface is not eroded, so that the life can be further extended.

[Brief description of drawings]

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

FIG. 2 is a front sectional view showing a state where heat transfer brazing is performed using the heating element of FIG.

[Explanation of symbols]

 2 ... Heating part 4 ... Heat source 10 ... Joined member 11 ... Brazing material

Claims (1)

[Claims] 1. A heat source (4), and a heating part (2) for receiving heat from the heat source, the heat conduction of the heating part (2) mainly due to contact with a member to be joined (10), A heating element for heat transfer brazing for melting a brazing material (11) having a lower melting point than that of a member to be joined to join the members (10) and (10), wherein the heating section (2) is non-conductive. A heating element for heat transfer brazing, which is formed of a conductive ceramic.