JPH03155463A - Vacuum brazing method for container cap - Google Patents

Abstract

PURPOSE:To avoid defective welding by burying brazing filler metal in a groove on the circumference of a cap body and heating a part for burying brazing filler metal with a densely converged electron beam to melt the brazing filler metal. CONSTITUTION:The cap body 3 is mounted on the opening part 2 of the container 1 under a vacuous state and the cap body 3 is welded by brazing filler metal 4 to the opening 2 of the container 1. In that case the brazing filler metal 4 is buried into the groove 3A formed along the circumferential edge of the cap body 3 in advance. The buried part of the brazing filler metal 4 on the circumferential edge of the cap body 3 is heated by a densely converged electronic beam 5 and the brazing filler metal 4 is melted and welded. In this way, even when a gasifying property by high temperature heating is attached to the material, it can be brazed.

Description

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

[Conventional technology]

Conventionally, as a means of welding the airtight lid of thin-walled metal vacuum containers,
As shown in FIG. 3 in a vacuum chamber, a metal lid C is placed in the opening B of a metal container A with a brazing material inserted, and the whole is heated to the melting temperature of the welding member. It is common practice to use a so-called vacuum brazing method in which the two are welded and hermetically sealed.

In this case, the heating means may be to uniformly heat the object as a whole in a vacuum furnace, or to locally heat the object by bringing a high-frequency induction heating coil close to the object [Problems with the conventional technology] ] By the way, among the heating means mentioned above, the former means for heating the inside of the vacuum furnace to a uniform temperature is used when the container A or the lid C is attached with a material that does not have heat resistance, or when the material is gasified by high-temperature heating. There are problems in that it cannot be applied when materials with special characteristics are attached, or when there is internal residual stress and distortion occurs due to high-temperature heating. Although it can be said that the heating conditions are small, there are problems in that the local heating zone is wide, there is considerable distortion especially for thin objects, and it is not easy to control the heating conditions.

Furthermore, in order to solve the above problem, it may be possible to perform local heating with a focused electron beam as shown in Figure 4, but in this case, if only the brazing material is heated with the electron beam E, only the brazing material will be heated. There is a problem that the brazing material may melt before the container A or the lid C, and the temperature of the brazing material is absorbed by the container A or the lid C, which has not yet reached the melting temperature, making welding impossible. Ta.

Therefore, in order to avoid such problems, it is necessary to take troublesome measures such as heating each of the container A and the lid C with an electron beam and melting the brazing filler metal using heat transfer. Ta.

[Problem to be solved by the invention]

The present invention solves the above problems and provides a vacuum brazing method for containers that has an extremely narrow local heating zone (therefore, does not cause distortion even for thin-walled objects, and can easily control temperature). This was done for the purpose of

C! [Technology that led to solving problem i] That is, the method for vacuum brazing a container lid of the present invention involves placing a lid on a container opening under vacuum and welding the lid to the container opening using a brazing material. In this step, the brazing material is embedded in a groove previously formed along the periphery of the lid, and the portion of the periphery of the lid where the brazing material is buried is heated with a tightly focused electron beam to melt the brazing material. It is characterized by welding by doing.

[Effect]

In the present invention, a tightly focused electron beam is used as a heating means for the brazing member.

This closely focused electron beam is one in which the focused state of the beam is set to a defocus of 2 to 5 mm.

This tightly focused electron beam makes the heating zone extremely narrow, and since the beam irradiation position can be changed steplessly, it is possible to narrow down and heat only the necessary areas, making it possible to heat thin objects that are prone to thermal distortion. This makes it possible to heat braze weld even objects in a stable state.

In the lid to which the electron beam is irradiated, a brazing material is embedded in advance in a groove provided on the periphery, and heating is performed through the lid.

Therefore, even when the brazing material reaches its melting temperature, the lid continues to be heated as well, so that heat from the brazing material is prevented from escaping toward the lid, allowing efficient brazing.

Furthermore, since the electron beam can be irradiated directly onto the brazing material through the lid, the irradiation means can be simplified and work efficiency can be improved.

〔Example〕

Next, the present invention will be explained in detail.

As shown in FIG.
For the metal plate container A of No. 1, a circular plate 3 with a diameter of 34 m is placed as a lid C over the circular hole 2, and a concave groove is formed around the circular plate 3 as shown in Fig. 1 (C). A brazing welding member 4 was buried in the hole 3A, and in a vacuum state, an electron beam 5 was irradiated from the upper surface of the lid 3 to heat and melt it.

The temperature rise state at this time is as shown in the graph shown in Figure 2, and the temperature of the container 1, lid 3, and brazing material 4 rises uniformly and simultaneously only within a very limited range, When the attachment material 4 reached the melting temperature, the surrounding area was uniformly welded.

Further, after welding, when the electron beam irradiation was stopped and the container was slowly cooled to room temperature, almost no distortion occurred in the container 1 and the lid 3.

〔effect〕

As explained above, this invention heats the brazing material through the lid with a highly focused electron beam, so when the brazing material melts, both the lid and the container tend to reach the melting temperature at the same time, and only the brazing material It is possible to easily avoid welding defects due to preliminary melting of the metal, and since it does not use heat transfer, there is less wasted heat. If welding is possible and the heating area is localized, the container or lid is made of a material that is not heat resistant, or if the material is attached to a material that gasifies when heated to high temperatures. It has various effects such as making it possible to perform brazing welding.

[Brief explanation of the drawing]

Figures 1 (b) and (c) are a plan view, a sectional view, and an enlarged sectional view of essential parts of an embodiment of the present invention; Figure 2 is a graph showing the heating state of the embodiment; Figures 3 and 4; The figures are a perspective view and a sectional view showing a conventional example.

Claims (1)

[Claims] (1) When a lid is placed on a container opening under vacuum and the lid is welded to the container opening using a brazing material, the brazing material is embedded in a groove formed in advance along the periphery of the lid, A vacuum brazing method for a container lid, characterized in that the portion where the brazing material is buried in the periphery of the lid is heated by a tightly focused electron beam to melt the brazing material and welding is performed.