JPS61106120A - Production of vacuum double container made of stainless steel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a vacuum double container made of stainless steel, specifically, a method for manufacturing a stainless steel vacuum container for use in portable thermos flasks, pots, ice jars, jars, etc. This invention relates to a method for manufacturing a vacuum double container manufactured by.

(Prior Art) In recent years, a metal vacuum double container made of metal material to improve mechanical strength has been proposed and put into practical use. When manufacturing this type of metal vacuum double container, the method of evacuating the space between the inner and outer containers and then sealing the space under vacuum includes, for example, Japanese Patent Application Laid-Open No. 59-37914; As described in Japanese Patent No. 59-103633, the air is evacuated through a tip tube attached to an outer container, and after reaching a predetermined degree of vacuum, the tip tube is pressed against the tube to seal the vacuum. As described in 96e No. 22 and Japanese Unexamined Patent Publication No. 58-192516, after joining the metal inner container and the outer container body at the mouth, the outer container bottom member having an exhaust port at the bottom is removed. A metal closing member is joined to the container body to form a double wall structure, and is inverted, and a metal closing member for closing the exhaust port is placed on the bottom member of the outer container with a gap between it and the exhaust port, A known method is to place a brazing material near the exhaust port, evacuate the material while heating it in a vacuum heating furnace, and then melt the brazing material and braze a closing member to the bottom for vacuum sealing.

(Problem to be solved by the invention) However, since the method using a chip tube does not use waxing material, etc., gas does not flow into the vacuum space between the inner and outer containers during vacuum sealing, as in the case of wax entertainment. However, since there is a limit to how short the length of the tip tube can be, there is a problem in that the height of the product increases by the length of the tip tube. On the other hand, the brazing method has the problem that the processing temperature is limited because of the brazing material, and that temperature control becomes complicated because the thermal cycle in the vacuum heating furnace is multistage. In other words, in this method, when flux is used, gas flows into the vacuum space between the inner and outer containers, lowering the degree of vacuum, so it is necessary to braze without using flux. In addition to flashing the surface, a brazing material such as nickel solder having a melting point of about 900 to 1070°C must be used. Moreover, when stainless steel is heated to a high temperature or cooled from a high temperature, the solid solution carbon becomes carbide and precipitates in a certain temperature range (generally about 450 to 850 degrees Celsius) and becomes sensitive. To avoid long-term exposure to the dangerous temperature range of sensitization, rapidly raise the temperature to 850℃ or higher, perform vacuum exhaust treatment and braze welding at that temperature, and place it in a vacuum heating furnace when cooling from high temperature. There were problems in that an inert gas had to be supplied for rapid cooling, the power consumption of the vacuum heating furnace was large, and the use of an inert gas increased manufacturing costs.

(Means for Solving the Problems) The present invention basically focuses on the characteristics of a vacuum heating furnace, that is, when the power supply to the heater of the vacuum heating furnace is stopped, the temperature inside the furnace and the temperature of the object to be heated decreases. Taking advantage of the property that the temperature drops rapidly from several tens of degrees to hundreds of degrees, vacuum evacuation treatment is performed at a relatively low temperature of 300 to 600 degrees Celsius, avoiding the dangerous temperature range of sensitization. A metal film is formed in advance by coating with a metal that recrystallizes at a relatively low temperature, and after evacuation treatment, vacuum confinement is performed by press-welding in a vacuum. Although it is possible to pressure-weld the stainless steel itself, in this case, the stainless steel must be heated to over 800°C, so problems due to the sensitizing nature of stainless steel cannot be avoided. .

As the material for forming the metal coating, aluminum, steel, or one of their alloys is used. Note that any method such as melt plating, vacuum evaporation, sputtering, electrolytic plating, chemical plating, thermal spraying, etc. may be used as the coating method.

In addition, in a vacuum double container, a getter is usually disposed in the space in order to maintain the degree of vacuum in the space between the inner and outer containers for a long period of time. 7. A non-evaporable getter that is activated at a relatively low temperature and does not lose its gas adsorption function even when wet with water or silver mirror reaction solution. It is preferable to use a non-evaporable getter based on an r-V-Fe ternary alloy or a Zr-Ni-Nb ternary alloy.

Additionally, in order to improve the heat retention of the vacuum double container, a copper or silver plating layer is formed on at least the outer surface of the inner container, among the surfaces of both the inner and outer containers that form the vacuum space. Alternatively, as in the example, in order to cause a silver mirror reaction on the stainless steel surface, the stainless steel member to be plated is baked in an oxidizing atmosphere at 250 to 550°C for several minutes to several hours to oxidize the outer surface. After forming a film and joining it with other members to form a double-walled container, a known silver mirror reaction solution is injected from the exhaust port into the space formed between the inner container and the outer container. It may be formed by a silver mirror reaction.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the figure, l is an inner container made of stainless steel, 2
is an outer container made of stainless steel, and after inserting the inner container 1 from the open end 3a of the outer container main body 3 and joining them by welding and welding at the mouth 4, the outer container main body 3 is assembled. By joining the outer container bottom member 5 to the open end 3a, a double-walled container 20 is constructed. Outer container bottom member 5
has an exhaust port 5a at its bottom, a metal MM9 made of copper is formed by electrolytic plating on the surface of the protrusion 5c of the bottom wall 5b forming the exhaust port 5a, and a holding member 6 is formed inside the metal MM9. The getter 7 is installed. Note that the metal coating 9 made of copper is laminated on a nickel plating layer formed in advance on the surface of the projection 5C by electrolytic plating. Further, in order to form silver mirror plating on the outer surface of the inner container 1, it was previously fired in an oxidizing atmosphere at 350° C. for 30 minutes to form an oxide film on the outer surface.

The double-walled container is constructed by injecting a known silver mirror reaction solution into the space 8 formed between the inner container 1 and the outer container 2 through the exhaust port 5a, and causing a silver mirror reaction to occur on the outer surface of the inner container 1. A silver mirror layer is formed on the surface, washed with water, and dried.

Next, the double-walled container 20 having the above configuration is turned upside down as shown in FIG. hand,
Set in vacuum heating furnace 25. Note that the closure member 10 has a metal covering 1111 made of copper formed by electrolytic plating at a portion to be pressed against the bottom wall portion 5b of the outer container 2, and a metal covering 1111 made of copper is formed by electroplating.
A plurality of recesses 12 are formed in the outer wall so as to form a sufficient ventilation path 12 between the exhaust port 5a and the exhaust port 5a when placed on the outer wall.

Next, the inside of the vacuum heating furnace 25 is evacuated while being heated to 450°C in the vacuum heating furnace 25, and the degree of vacuum in the space 8 between both containers is reduced to I.
Create a high vacuum of O-'Torr or more.

At this time, the gas in the space 8 is exhausted into the vacuum heating furnace 25 through the exhaust port 5a4: the ventilation path 14 formed between the formed protrusion 5C and the recess 1°2 of the exhaust port closing member IO. Ru. The space 8 of the container 20 is evacuated to a predetermined degree of vacuum, and the temperature inside the vacuum heating furnace 25 further increases to a predetermined temperature, e.g.
When the temperature reaches 550°C, the getter 7 is activated, while the jig 15 disposed in the vacuum heating furnace 25 descends, pushes the exhaust port closing member 10 into the exhaust port 5a of the container 20, and closes the third
As shown in the figure, the metal coating 1 of the exhaust port closing part tltlo
1 and the metal cover 11i9 of the protrusion 5C of the bottom member 5 are joined together, the exhaust port closing member IO is pressed against the container 20 at the joint 16, and the vacuum confinement process is completed.

At the same time, the power supply to the vacuum heating furnace 25 is stopped, so that the temperature inside the furnace and the temperature of the container rapidly decrease by 10 degrees from the maximum temperature increase. Therefore, since the time period during which the stainless steel, which is the material of the vacuum double container, is exposed to temperatures dangerous for sensitization is extremely short, there is no risk of sensitization, especially if no inert gas is supplied into the furnace.

In the above examples, stainless steel plates processed into a predetermined shape and then electrolytically plated to form a copper coating were used as the outer container bottom member and the closing member. You may use a processed material, or you may use a material coated with copper alloy, aluminum, or an alloy thereof instead of copper.

Further, although the exhaust port is formed in the bottom member of the outer container, it is not necessarily necessary to form it in the bottom member, and it may be formed in another part. Furthermore, although it is not necessarily necessary to form a protrusion on the exhaust port forming part, forming a protrusion has the advantage that the contact area with the exhaust port closing member is reduced, so that pressure contact can be made with a weak suppressing force.

(Effects) As explained above, according to the present invention, vacuum evacuation processing, getter activation, and vacuum confinement can be performed at an extremely low temperature compared to conventional methods. The required time can be significantly shortened, the thermal cycle in the vacuum heating furnace can be simplified, and the power consumption can be reduced.

In addition, the maximum temperature during vacuum evacuation processing and vacuum sealing is low, and the time that the stainless steel, which is the material of the container, is exposed to the dangerous temperature of sensitization is short, so sensitization can be prevented.
Moreover, since no wax or flano gas is used, there is no reduction in the degree of vacuum due to gas generation during vacuum sealing.
The quality of vacuum double containers can be made uniform. Furthermore, since there is no need to use an inert gas during cooling, excellent effects can be obtained, such as cost savings and the ability to reduce the manufacturing cost of the vacuum double container.

[Brief explanation of the drawing]

Fig. 1 is a schematic half-sectional explanatory diagram showing an example of the manufacturing process of a stainless steel vacuum double container by the method of the present invention, Fig. 2 is an enlarged view of the main part, and Fig. 3 is a stainless steel vacuum container manufactured by the method of the present invention. FIG. 2 is a sectional view of a main part of a steel vacuum double container. 1 - Inner container 2 - Outer container 3 - Outer container main body 4 - Mouth part 5 - Outer container bottom member 5a - Exhaust port 5b - Bottom wall part 5c - Projection part 9.11 - Metal coating lO - Exhaust outlet closing member - 2 ~ recess
14~Vent passage 20~Double-walled container 25~Vacuum heating furnace

Claims (1)

[Claims] (1) In a method for manufacturing a vacuum double container made of stainless steel, which has a double wall structure consisting of an inner container and an outer container made of stainless steel, and the space formed between the two containers is vacuum insulated. , while forming a double-walled container having a metal coating made of aluminum, copper, or one of their alloys around the exhaust port, and forming a double-walled container at a portion of the double-walled container that is to be joined to the exhaust port forming portion. An exhaust port closing member is formed that grows a metal coating made of the same material as the metal coating, and the exhaust port closing member is placed above the exhaust port with an air passage formed between the exhaust port and the vacuum heating furnace. After exhausting the space between the inner and outer containers at a temperature of 300 to 600°C, the exhaust port closing member is pressed against the exhaust port forming portion to seal the vacuum double container made of stainless steel. Production method.