JPH02121796A - Brazing method - Google Patents

Abstract

PURPOSE:To execute brazing in a short time even in case of a large-sized work by inserting a material to be brazed into an airtight container manufactured by a sheet metal, and heating the inside of the airtight container by holding it in an inert gas atmosphere of a specific pressure or below or in a vacuum. CONSTITUTION:Plate-like seal use metallic plates (capsule materials) 1a, 1b consist of an SUS 304 material whose plate thickness is about 1mm, its mouthpiece 20 also consists of the same material, and both of them are welded as to the outside peripheries by a seal welding part 4, by which an airtight capsule is formed. A heater coil 3 surrounds the capsule material and consists of a molybdenum wire. The upper structural material 10 and the lower structural material 11 form an impeller, respectively and a blade 12 and a material to be brazed (work) 2 are provided projectingly. Subsequently, a brazing filler metal 6 is set and a mold releasing agent 7 is applied, and thereafter, the work 2 is surrounded by the capsule, and seal welding is executed. Next, from the base 20, the inside of the capsule is allowed to form a vacuum to <=10<-1>Torr, and thereafter, the work is held together with the capsule at 1000 deg.C for about 30 minutes by the heater coil 3. In such a way, even in case of a large-sized work, brazing can be executed in a short time without using an expensive vacuum furnace.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a brazing method.

[Conventional technology]

Impeller, compressor diaphragm.

In the production of craft steel, brazing is conventionally performed by pouring brazing filler metal onto the workpiece and then heating the workpiece at a heating rate of about 60°C/hr in a vacuum brazing furnace. Since it takes a long time to braze, the construction period becomes longer.

It is possible to increase the heating rate, but for example, if the impeller has an outer diameter of 400 mm or more and the soil structure material and lower horizontal construction material are each 30 mm or more in thickness, the heating rate may be increased. is 100℃/h ~ 150℃/
When the temperature reaches about h, a difference in temperature distribution occurs in the material to be brazed, causing deformation and creating a gap at the brazing interface, making it impossible to perform brazing in a negative manner.

Therefore, even if a bulk important object is placed on top to apply pressure, the temperature may not rise uniformly or it may take a long time to obtain a uniform temperature, which may lead to alloying of the brazed parts. If you do too much, the results will not be good. Workpieces may be restrained with jigs, but large jigs are required for large materials.
The result is the same as above.

Even if the brazed interface is tightened with screws, etc., residual stress will occur if there is too much temperature difference due to rapid heating in the low temperature range, and the screw will stretch in the high temperature range, making it impossible to maintain a good interfacial gap.

[Problem to be solved by the invention]

The present invention was proposed in view of these circumstances, and the purpose is to provide an economical brazing method that can braze even large workpieces in a short time without using an expensive vacuum furnace. do.

(Means for Solving the Problems) For this purpose, the present invention inserts a brazing material into an airtight container made of thin sheet metal, and seals the inside of the airtight container at 10-
' It is characterized by being heated while being held in an inert gas atmosphere of Torr or less or in a vacuum.

[Effect]

According to this method, since the workpiece is sealed with a metal membrane, the brazing material to be covered is kept in a vacuum, so a clean brazed part can be obtained, and the entire interior of the brazing membrane is kept in a vacuum. Therefore, as the capsule material deforms, atmospheric pressure acts on the brazing material, and the bonding interfaces of the workpieces are pressed against each other, allowing for good brazing.

[Example] An embodiment in which the present invention is applied to brazing a large impeller will be explained with reference to the drawings. Fig. 1 is a longitudinal cross-sectional view of the whole, and Fig. 2 is a partial plan view showing the impeller of Fig. 1. .

In the above diagram, la and lb are flat plate-shaped sealing metal plates (capsule material), each of which is made of SUS with a thickness of 1.
It is made of 304 material, and its base 20 is also made of the same material.
The outer peripheries of both are hermetically welded at a seal weld 4 to form an airtight capsule. 3 is a heater coil surrounding the capsule materials 1a and 1b, and is made of molybdenum wire.

10.11 are the main structural members forming the impeller, respectively;
In the lower structural member, the lower horizontal member 11 has blades 12. A brazing material 2 is provided protrudingly.

Brazing of such an impeller is performed by the following procedure.

+11 Brazing material 6 between main structural member 10 and lower horizontal member 11
(BNi-7).

(2) After applying a mold release agent 7 to the material to be brazed, the workpiece is surrounded with capsule materials 1a and Ib, and seal welding 4 is performed.

(3) From the cap 20, use a vacuum pump to pump the inside of the capsule for 10 minutes.
After evacuation to -2 Torr or less, heater coil 3
Capsule the work in la.

Heat with lb.

(4) The heating rate was 100°C/hr, and the temperature was maintained at 1000°C for 30 minutes for brazing.

(5) Cooling is performed at the same rate as the temperature increase rate.

(6) After cooling, the seal weld is plasma cut and removed.
Take out the workpiece and inspect it to confirm that good brazing has been performed.

According to such a method, the following effects can be achieved.

Tl) The material to be brazed is inserted into a container made of a thin metal film and heated while maintaining a vacuum, so the capsule deforms and atmospheric pressure acts on the main structural material and lower horizontal members of the material to be brazed. and press them both against each other.

As a result, in this method, at high temperatures where the brazing material melts, creep deformation occurs due to the action of atmospheric pressure, and the brazed joint interface is kept narrow and properly maintained, resulting in good brazing.

(2) High-precision brazing is possible without the need for an expensive vacuum furnace.

(3) Since the temperature increase rate can be increased for large materials, the brazing cycle time is shortened and productivity is increased.

(4) The method of the present invention was applied to a carbon steel impeller with an outer diameter of 1000 mm, a height of the main structural member h' = 5 on, a height of the lower horizontal member h = 100, a dragon blade height of 30 mm, and a number of blades of 7. However, the above effect has been proven.

〔Effect of the invention〕

In short, according to the present invention, a brazing material is inserted into an airtight container made of thin sheet metal, and the inside of the airtight container is heated by maintaining the inside of the airtight container in an inert gas atmosphere of 10-' Torr or less or in vacuum. By doing so,
The present invention is extremely useful industrially because it provides an economical brazing method that can braze even large workpieces in a short time without using an expensive vacuum furnace.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention applied to an impeller, and FIG. 2 is a partial plan view showing the impeller of FIG. 1. la, lb... Fully bent thin plate capsule material, 2... Brazing material (work), 3... Heater coil, 4...
Seal welding part, 5... joint surface, 6... brazing metal, 7.
... Mold release agent, IO... Earth structure material, 11... Bottom horizontal construction material, 12... Feather, 20... Base. Agent: Masafumi Tsukamoto, Patent Attorney

Claims (1)

[Claims] Brazing is characterized by inserting a brazing material into an airtight container made of thin sheet metal, and heating the inside of the airtight container while maintaining it in an inert gas atmosphere of 10-1 Torr or less or in a vacuum. Method.