JPH0415688B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a metal thermos flask.

(Prior Art) In recent years, metal thermos flasks made of metals such as stainless steel have been put into practical use in place of glass thermos flasks that are susceptible to mechanical shock. As a manufacturing method of this kind of metal thermos flask, for example,
As described in No.-103633 or JP-A-60-29118, at least the inner container is fired to form an oxide film, while a getter is applied to the space-forming surface of one of the constituent members of the inner container and the outer container. Put it on,
Next, the constituent members of both the inner and outer containers are joined to form a double container, and silver plating is applied by introducing a silver plating liquid from the tip tube provided in the bottom member of the outer container, and then the tip tube is subjected to an exhaust sealing treatment. method is known.

(Problems to be Solved by the Invention) However, in the above method, since the plating process is performed after forming a complete double wall structure, visual inspection is required to check whether the plating layer formed by the plating process is good or not. There was a problem in that the quality of the plating process could not be determined unless a heat retention test was performed after the exhaust sealing process. Moreover, if the plating process becomes defective for some reason, it is nearly impossible to disassemble the double container and reuse its constituent parts, resulting in the problem of poor product yield. It was hot. In addition, when non-evaporable getters such as Zr-V-Fe ternary alloys and Zr-Ni-Nb ternary alloys are immersed in the plating solution, the adsorption capacity is not significantly impaired, but it is still about 10%. It has become clear that a decline in

Therefore, the main object of the present invention is to enable the quality of the plating layer to be determined before the exhaust sealing process, and to reuse the constituent members of the double container if the plating is defective. Another object of the present invention is to prevent the getter adsorption ability from decreasing during the manufacturing process.

(Means for Solving the Problems) In order to solve the above problems, the present invention has a double wall structure consisting of an inner container and an outer container made of metal, and evacuates the space formed between the two containers. In the method for manufacturing a metal thermos flask, at least the outer container shoulder member of the outer container constituent members is joined to the inner container to form a semi-finished product, the semi-finished product is fired in an oxidizing atmosphere, and then the liquid filling port is closed. The lid body having the above-mentioned structure is removably attached to the open end of the outer container component joined to the inner container, and after the electroless plating liquid is injected from the liquid injection port to perform the plating process, the lid body is removed, and then the lid body is removed. The present invention is characterized in that an outer container bottom member having an exhaust port is joined to the open end of the outer container component and subjected to exhaust sealing treatment.

In an embodiment of the present invention, the getter is attached to the outer container bottom member, the outer container bottom member is attached to the outer container body after plating treatment, and the getter is activated in the exhaust sealing step.

Further, in an embodiment of the present invention, silver or copper plating is performed as electroless plating.

(Function) According to the method of the present invention, at least the outer container shoulder member of the outer container constituent members is joined to the inner container to form a semi-finished product, and the outer container shoulder member is replaced with other outer container constituent members other than the outer container shoulder member. If plating is performed after the lid is removably attached to the plating, the formation state of the plating layer can be visually inspected by removing the lid after the plating. Furthermore, if the getter is attached to the bottom member, the getter will not be immersed in the plating solution during the plating process, so the adsorption ability of the getter will not decrease, and therefore the Zr-V-
This makes it possible to use not only non-evaporable getters such as Fe ternary alloys and Zr-Ni-Nb ternary alloys, but also conventionally known inexpensive getters.

In the method of the present invention, a firing treatment is performed in order to impart hydrophilicity to a metal surface, for example, a stainless steel surface, and to ensure the formation and adhesion of a plating layer. This firing treatment is usually performed at 250 to 550°C for 5 to 180 minutes in air or an oxidizing atmosphere such as an oxygen-containing atmosphere, preferably for 300 to 180 minutes.
It is carried out for 10-60 minutes at ~450°C. This is because if the firing temperature is lower than 250°C, a sufficient oxide film will not be formed, or it will take a long time to form, inhibiting the precipitation of silver or copper, and increasing manufacturing costs. This is because if it exceeds this, the stainless steel base will undergo a transformation. The firing time can be set arbitrarily as long as it is within the above temperature range, but if it is less than 5 minutes, it will be difficult to form a sufficient oxide film when the firing temperature is low, and if it exceeds 180 minutes, it will not be necessary when the firing temperature is high. It is desirable to perform the firing within the above-mentioned range since the above firing treatment increases energy loss and also inhibits the precipitation of silver or copper.

The electroless plating layer is formed on the oxide film, and can be formed by a known method using a known silver mirror reaction solution or chemical copper plating solution. In addition, before electroless plating, in order to speed up the deposition rate of the plating-forming metal and at the same time deposit it uniformly, the oxide film is sensitized by being wetted with a known sensitizing solution containing stannous halide as the main component. Furthermore, after sensitization, activation may be performed with an activating solution containing a noble metal such as silver salt or palladium chloride.

Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Internal capacity made of 0.5mm thick stainless steel (SUS304)
A 750ml inner container main body 1a and an inner container bottom member 1b are manufactured and joined together to form the inner container 1, while the shoulder member 2c, body member 2a, and bottom member of the outer container 2 are made of 0.6 mm thick stainless steel plates. After the inner container 1 and the outer container shoulder member 2c are welded and joined at their mouth portions 3, the outer container body member 2a is joined to the open end 4 of the shoulder member 2c by welding to form a semi-finished product 6. This was then baked in air at 450°C for 15 minutes (Figure 1). Next, the outer container body member 2a
A lid 8 having substantially the same shape as the outer container bottom member 2b and provided with a liquid injection pipe 7 was removably fitted into the open end 5 of the container to form a double wall structure (FIG. 1). In addition, the lid body 8
The portion fitted into the opening 5 of the outer container body member 2a is formed into a tapered shape.

Next, an aqueous solution containing 10 ppm of stannous chloride is injected into the space 9 formed between the inner container 1 and the outer container body member 2a from the liquid injection pipe 7 forming the liquid injection port 15 to fill the space. After sensitizing the forming surface and discharging the aqueous solution, it is washed with water, and an activating solution prepared according to the following recipe is injected into the space from the injection pipe 7, and the double bottle is held horizontally in the axial direction and rotated at high speed. to activate the outer surface of the inner container 1.

(Prescription of activation liquid) Dissolve 10g of silver nitrate in a small amount of water, add 28%
Aqueous solution made by adding 500ml of ammonia water and water to make 4800ml, and further dissolving 10g of sodium hydroxide.
Add 200ml to make the total volume 5000ml, and use this as the stock solution. Add 1900 ml of water to 100 ml of this stock solution to obtain an activation solution containing 0.01% by weight of silver nitrate.

After activation treatment, drain the liquid, wash with water, and remove _CuSO4 .
Chemical copper plating solution 240, which is a mixture of 120 ml of a solution containing 35 g/5H ₂ O, 50 g/NaOH, and 170 g Rotussel salt and 120 ml of 3.7% formalin solution.
ml into the space through the injection pipe 7, hold the double bottle horizontally in the axial direction, and rotate it at high speed at 40°C for 5 minutes to clean the outer surface of the inner container 1, the outer container body member 2a, and the outer container. A chemical copper plating layer is formed on the inner surface of the container shoulder member 2c (FIG. 1).

Next, after washing with water, compressed air is supplied from the liquid injection pipe 7 of the lid 8 to separate the lid 8 from the open end 5 of the outer container body member 2a (Fig. 1), and the portion where the plating layer is formed is visually inspected. and dry the good products at 230℃ (first step
figure). If it is determined to be defective, the shell is immersed in nitric acid to dissolve and remove the deposited shell, and then re-plated.

Next, the outer container bottom member 2b, to which the getter has been attached in advance, is joined to the open end 14 of the outer container body member 2a by welding or other means to form a double wall structure (FIG. 1). After vacuum evacuation through the tube, the tip tube 10 was sealed, and a bottom cover (not shown) was attached to the bottom of the tube to obtain a stainless steel thermos flask with an internal capacity of 0.75.

In order to examine the heat retention ability of the stainless steel thermos flask thus obtained, measurements were made under the following conditions using the test method specified in JIS 2005, and the heat retention effect for 24 hours was 63°C.

[Test conditions] Hot water pouring temperature: 95℃ Hot water amount: Full Plug: Sealed plug (45mmφ) Ambient temperature: 20℃ Example 2 Using the same stainless steel plates as Example 1, the inner container 1 with an inner capacity of 750ml and the outer container were The shoulder member 2c, body member 2a, and bottom member 2b of the container 2 are manufactured, and the inner container 1 and the outer container shoulder member 2c are welded at their openings 3 to form a semi-finished product, which is heated in air for 300 minutes. ℃30
Fired separately.

On the other hand, the bottomed cylindrical lid 8 is attached to the outer container shoulder member 2c.
The liquid injection pipe 7 provided in the lid body 8 is inserted into the space between the inner container 1 and the lid body 8.
Injecting an aqueous solution containing 10 ppm of stannous chloride,
The outer surface of the inner container was activated and washed with water. Next, a silver mirror reaction solution with the following formulation is injected into the space through the injection tube 7, held horizontally and rotated at high speed to deposit silver and form a silver plating layer on the outer surface of the inner container. did.

(Prescription of silver mirror solution) Dissolve 10g of silver nitrate in a small amount of water and add 28%
Add 500ml of ammonia water and distilled water to make 4800ml.
An aqueous solution in which 10g of sodium hydroxide is further dissolved
Add 200ml to make the total volume 5000ml, and use this as Solution A. Separately, add 20g of sucrose to 50g of distilled water.
ml of the aqueous solution, add 0.25 ml of concentrated nitric acid, boil it, add 5 ml of 37% formaldehyde aqueous solution, add distilled water to make a total volume of 5000 ml, and use this as Solution B. The volume ratio of the above A liquid and B liquid is 1:1.
Mix to make a silver mirror solution.

After the plating process, the lid 8 is removed from the semi-finished product in the same manner as in Example 1, and then the outer container body member 2a is removed.
is joined to the outer container shoulder member 2c, and the bottom member 2b, on which the getter is attached in advance, is joined to the open end 5 of the outer container body member 2a to form a double-walled container, and the rest is the same as in Example 1. A stainless steel thermos flask was manufactured.

When this stainless steel thermos flask was tested for its heat retention ability in the same manner as in Example 1, the same results as in Example 1 were obtained.

In the above embodiment, the chip tube provided in the bottom member is used for the exhaust sealing process, but a through hole is simply provided in the bottom member, and this through hole is used as a liquid injection port. After the exhaust treatment is performed through the opening, it may be heated to melt the brazing material that has been placed in advance above the through-hole at a predetermined interval to hold the closing plate, and to bring the closing plate into solder contact.

(Effects) As is clear from the above description, according to the present invention, after baking the inner container in a semi-finished state with at least the outer container shoulder member attached, and assembling the lid into a double wall structure with the lid as a dummy, After electroless plating and forming the plating layer, the lid is removed and the outer container members are joined, so visual inspection can be performed, and even if a plating failure occurs, the lid can be removed and immersed in nitric acid. Since the plating layer can be removed by simply removing the plating layer, both the inner and outer container members can be reused. Further, since electroless plating can be performed without bringing the getter into contact with an electroless plating solution, the adsorption ability of the getter is not reduced, and therefore, an inexpensive getter can be used. Furthermore, since the plating layer does not precipitate in areas other than the fired areas, excellent effects such as the ability to save plating solution can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing the manufacturing process of a stainless steel thermos flask according to the method of the present invention. 1 - Inner container, 2 - Outer container, 2a - Outer container body member, 2b - Outer container bottom member, 2c - Outer container shoulder member,
3-mouth portion, 4, 5-opening end, 7-liquid injection tube, 8-lid body, 15-liquid injection port.

Claims (1)

[Scope of Claims] 1. In a method for manufacturing a metal thermos flask having a double-walled structure consisting of a metal inner container and an outer container, and in which the space formed between the two containers is evacuated, the outer container configuration Among the members, at least the outer container shoulder member is joined to the inner container to form a semi-finished product, and after firing the semi-finished product in an oxidizing atmosphere, a lid body having a liquid injection port is attached to the outer container joined to the inner container. It is detachably attached to the open end of the container component, and after plating is performed by injecting electroless plating liquid from the liquid injection port, the lid is removed, and then the outer container bottom member having the exhaust port is attached to the outer container. 1. A method for manufacturing a metal thermos flask, which comprises joining an open end of a component and subjecting it to exhaust sealing treatment. 2. The method according to claim 1, wherein a getter is attached to the inner wall surface of the outer container bottom member, and the getter is activated in the exhaust sealing treatment step. 3. The method according to claim 1 or 2, wherein the electroless plating is silver or copper.