JPS5936528B2 - Manufacturing method of metal thermos - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a metal thermos flask by a vacuum brazing method, which prevents softening of the metal caused by the method,
The purpose is to provide a method that is easy to process.

Generally, metal thermos flasks are manufactured by brazing the inner and outer chambers at the mouth and then drawing a vacuum between the inner and outer chambers through a vacuum port installed at the bottom of the outer chamber. The effect cannot be maintained for a long time due to degassing etc.

In addition, in order to maintain the desired vacuum insulation, it is necessary to repeatedly draw the vacuum as needed during use, which is complicated, so a vacuum method that allows virtually complete degassing from the wall surface and unifies the manufacturing process is recommended. A manufacturing method using bell dimensions has been proposed.

The method includes at least one joint between an inner and outer tank made of metal plates such as iron, stainless steel, copper, or aluminum, and a joint between a lid and an exhaust hole that exhausts the space between the inner and outer tanks. Set the solder material in advance to the 10”
A thermos flask is manufactured by brazing the joint by heating the solder material to a temperature higher than the molten temperature in a vacuum brazing furnace maintained at a temperature below Torr.

According to this method, when brazing the inner and outer tanks of a thermos bottle, there is an advantage that not only the vacuum heat treatment but also the evacuation of the inner and outer tanks can be performed at the same time. This causes the inconvenience that the tank is annealed and softened.

For this reason, reinforcement measures are generally taken, such as increasing the thickness of the plate in areas that require robustness, wrapping a reinforcing band around it, or creating a corrugated surface through press working, but this increases the weight, complicates the process, and increases costs. It causes an increase and is not desirable.

Moreover, it is desirable that the base metal of a metal thermos flask be as thin as possible.

The present invention has been proposed in order to compensate for the above-mentioned disadvantages.Prior to the heat treatment process, a suitable metal or a mixture of several kinds of metals different from the above-mentioned base material is applied to all or part of both sides or one side of the inner and outer tank base materials. Alternatively, a compound is applied or adhered in the form of a powder or film, and an alloy is formed by interdiffusion in the heat treatment process (brazing process) to increase the strength of this part.

In other words, dissimilar metals are attached to the parts that prevent the strength from decreasing in advance, and during the brazing process in the vacuum brazing furnace, these metals undergo interdiffusion and form a new alloy layer, which increases the strength compared to the base metal, which makes it possible to heat annealing. This is a method to compensate for the decrease in strength due to

The different metals that are the elements forming the new alloy may be a single substance, or may be a mixture or compound of several types of metals or a small amount of nonmetallic elements.

In addition, as for the shape, a paste made by mixing a binder with powder or a film is used as appropriate.

In either case, it is necessary to select a material that will diffuse into the base material of the inner and outer vessels to form an alloy that increases its strength.

It is also effective to add a metal such as titanium, which acts as a getter by combining with gas during vacuum heating, as a component of the mixture as the dissimilar metal.

That is, by applying a metal having a getter effect together, this metal acts as a getter while other metals form an alloy during vacuum heat treatment, thereby improving the degree of vacuum in the vacuum parts of the inner and outer chambers of the thermos flask.

The following experimental results are shown as examples of the present invention.

A test piece was prepared by coating both sides of a 5US304 plate with a thickness of 0.3 mm with a paste containing various metal powders based on nickel to a thickness of 0.05 mm, and a test piece of the same shape without coating. in the same furnace at a temperature of 10
Vacuum heat treatment was performed at 50° C. for 15 minutes.

After measuring and comparing the elastic modulus of each of these test pieces,
As shown in the figure, a significant difference was observed.

The paste made of metal powder used in this test was chromium 6
．． A powder mixture of 5 parts, boron 3.0 parts, iron 2.5 parts, silicon 4.5 parts, some carbon, and the rest nickel is made into a paste with a binder.

As described above, the present invention is a method of manufacturing a metal thermos flask by the vacuum brazing method, in which the above-mentioned metal powder or film is applied to the base material of the inner and outer vessels by heat treatment in exactly the same manner except for Cortenx. This is a method of forming a hardened layer on the base material to prevent the base material from softening due to heat annealing.

That is, vacuum heat treatment. In the manufacturing method of metal thermos flasks, which performs the brazing and vacuum evacuation processes all at once, the same heat treatment is used to prevent softening of the inner and outer tank base materials due to annealing and increase strength without adding any other processing steps. It can be done.

Therefore, the plate thickness of the inner and outer tank base materials can be reduced, and there is no need for special processing such as providing reinforcing bands or creating corrugated surfaces.

This allows the metal thermos flask manufactured by the vacuum brazing method to be lightweight, compact, and robust.

Furthermore, since a hardened layer is formed on the surface of the base material, it is possible to improve not only mechanical strength but also corrosion resistance and heat resistance.

As described above, the method for manufacturing a metal thermos flask according to the method of the present invention is an extremely simplified manufacturing method in which the steps of vacuum heat treatment, brazing, evacuation, and prevention of annealing and softening are performed all at once. Because the process is carried out under a high mud vacuum, a clean metal surface is obtained, which provides better radiation insulation efficiency than this ζ, and there is no reduction in the degree of vacuum due to degassing at a later date, and heating is uniform. Because the brazing is done on the ground, the brazing can be uniform and strong.Since it does not use flux, there is no staining caused by it, so it is of high quality and can maintain good insulation performance for a long time.Furthermore, as mentioned above, it is lightweight, compact, and robust. It has the characteristics and effects of “being something.”

[Brief explanation of the drawing]

The figure is a comparative diagram showing the relationship between stress and strain between a test piece treated according to the present invention and a test piece not treated.

Claims (1)

[Scope of Claims] 1. At least one type of metal powder or film different from the base material of the thermos bottle is coated or adhered to the entire surface or a desired part of the inner and outer barrels of the metal thermos flask, and the inner and outer metal sliding joints, the exhaust holes, etc. After filling one or both of the joints with the lid with a solder material, the inner and outer tank metal materials are vacuum heated by heating in a vacuum heating furnace under a vacuum of 10-"l'orr or less. Processing: A metal characterized in that processes such as vacuum evacuation of the inner and outer tanks and brazing of the joints are performed simultaneously, and different metals are diffused into the base material during the heating process to increase the strength of the base material. Method for manufacturing a thermos flask. 2 Applying or adhering at least one type of metal powder or film different from the base material of the thermos bottle to the entire surface or desired part of the inner and outer chambers of a metal thermos flask, and applying a vacuum to the powder or film of the different metal. After mixing metals that have a getter effect during heat treatment and applying brazing material to either or both of the base metal inner and outer sliding joints and the joint between the exhaust hole and the lid, the product is placed in a vacuum furnace. By heat-treating under a vacuum of 10-2 Torr or less, processes such as vacuum heat treatment of the metal materials of the inner and outer vessels, evacuation of the inner and outer vessels, brazing of the joints, etc. are performed simultaneously, and different types of f4 are removed during the heating process. 1. A method for manufacturing a metal thermos flask, which comprises diffusing into a base material to increase the strength of the base material.