JPH11159696A - Exhaust air closing method for vacuum container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive vacuum air closing method causing no leakage by which operation can be carried out in an atmospheric pressure without requiring any heating in a product manufacturing process using a negative pressure. SOLUTION: An exhaust port 2 is arranged in a vacuum container 1, and a closing member 3, which is brought into tight contact with the exhaust port 2 by means of pressure from the outside so as to close a plug, is arranged above the exhaust port 2 or in the position apart from the exhaust port 2. A vacuum cup 5, which is provided with an edge part keeping airtightness between the circumferential plane of the exhaust port 2 in the vacuum container 1 and connected to a vacuum pump, is pressed to the flat surface of the vacuum container 1. After exhausting of the vacuum container 1 is finished, the inside of the vacuum cup 5 is returned to the atmospheric pressure with the closing member 3 arranged in the exhaust port 2, and then, the vacuum cup 5 is released, so that the closing member 3 is brought into tight contact with the exhaust port 2 by means of a pressure difference between the pressure inside the vacuum container 1 and that of the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evacuation method for vacuum-sealing a product such as an evacuated container at atmospheric pressure.

[0002]

2. Description of the Related Art For example, a thermos bottle is well known as a container whose inside is evacuated for the purpose of heat insulation, for example. Recently, the manufacture of a large vacuum container using a vacuum space for the purpose of a heat insulation panel or the like has been studied. And the scope of application is expanding. Conventionally, as a method of vacuum-closing a vacuum-evacuated container in the atmosphere, a method is used in which an exhaust pipe is attached to the container and the container is evacuated and when a predetermined degree of vacuum is reached, the container is evacuated and sealed. Have been. For example, in the case of a thermos, for example, in the case of a glass thermos, the glass of the exhaust pipe is melted with a burner and sealed off. Similarly, in the case of a thermos made of stainless steel, the exhaust pipe is similarly crushed while being heated, pressed and joined, and then cut. Also, in the case of a thermos made of stainless steel, the whole is put in a vacuum chamber, heated and joined by brazing to assemble into a shape as a thermos, and vacuum sealing is performed at the same time. Although the above description has been made by taking a thermos as an example, a method of attaching a vacuum exhaust pipe provided with a butterfly valve or the like to the container depending on the type of the vacuum container and closing the valve after evacuation is also known.

[0003]

A general industrial product using a vacuum vessel is made of metal, and when exhausted by an exhaust pipe,
The exhaust pipe is also made of metal. In this case, the above-mentioned vacuum plugging method by press-fitting of the exhaust pipe is inconvenient for long-term vacuum plugging due to leakage from the pressure-pressed portion unless the metal is heated to a forgeable temperature. Therefore, for example, in a heat insulating panel or the like, a plastic structural material may be inserted into the inside in order to maintain the shape when a vacuum is applied, but there is a possibility that a problem of damage due to heating may occur. In addition, the method described in the above-described example of the stainless steel thermos, in which the whole is put in a vacuum chamber and brazed, is not only a condition that can be heated, but also a large article requires a large vacuum chamber. Will also be difficult. On the other hand, according to the vacuum plugging method using a vacuum valve such as a butterfly valve, vacuum plugging for a long period of time is possible, but it is expensive, and it takes up space and may become an obstacle for some products. Accordingly, it is an object of the present invention to provide an inexpensive and leak-free vacuum plugging method that can be operated in the atmospheric pressure without heating in a manufacturing process of a product using a vacuum.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a method for closing a vacuum vessel after the vacuum vessel is evacuated and closed, an exhaust port is provided in the vacuum vessel and a pressure from the outside is provided. A closing member, which closes and closes the exhaust port, is disposed on the exhaust port, and a vacuum cup coupled to a vacuum pump having an edge that keeps airtight between the vacuum container and a plane around the exhaust port. Pressed against the flat surface of the vacuum vessel,
After the evacuation of the vacuum vessel is completed, the inside of the vacuum cup is brought to atmospheric pressure and released, and the closing member is brought into close contact with an exhaust port by a pressure difference between the inside and the outside of the vacuum vessel. Is the way.

Further, in a method for closing a vacuum vessel after the vacuum vessel is evacuated and closed, an exhaust port is provided in the vacuum vessel, and an edge for maintaining airtightness between the vacuum vessel and a plane around the exhaust port is provided. A vacuum cup connected to the vacuum pump is pressed against the flat surface of the vacuum vessel, and a closing member that closes and closes the exhaust port with pressure from the outside is held in the vacuum cup at a position away from the exhaust port. After the evacuation of the vacuum vessel is completed, the inside of the vacuum cup is brought to atmospheric pressure and the vacuum cup is released while the closing member is pressed against an exhaust port, and the closing member is evacuated by a pressure difference between the inside and the outside of the vacuum vessel. This is a method for closing the exhaust of a vacuum vessel, which is characterized by being brought into close contact with a mouth. In each of the above methods,
After these steps, a vacuum sealing material is further poured between the exhaust port and the closing member.

[0006]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention. An exhaust port 2 is provided in a vacuum container 1 which is a product, and a spherical stopper 3 is arranged as a closing member that closes and closes the exhaust port by pressure from the outside. The exhaust port 2 is made of metal, for example, of the same material as the vacuum vessel 1.
Similarly, the spherical stopper 3 may be made of metal or the like. In this example, the exhaust port 2 has a conical shape such that the diameter decreases toward the inside. An O-ring 4 for vacuum is fitted into the inner surface of the exhaust port so as to maintain airtightness.

On the other hand, a vacuum cup 5 is provided as an exhaust device, and an edge portion 6 facing a plane around an exhaust port of the vacuum vessel.
have. An O-ring 7 is fitted in this edge portion as a gasket for maintaining airtightness, and the surface of the vacuum vessel 1 which is in contact with the periphery of the exhaust port 2 is also finished smoothly. The vacuum cup 5 is connected to a vacuum pump (not shown) through an exhaust pipe 8, and can be evacuated by pressing the vacuum pump against the vacuum vessel 1 to keep the airtight and operate the vacuum pump.
In FIG. 1, reference numeral 9 denotes a three-way cock, which can connect the vacuum cup to a vacuum pump or allow air to leak into the vacuum cup.

In the plugging method according to the present invention, the spherical plug 3 is disposed on the exhaust port 2 in advance to exhaust air. Before evacuation, the pressure P _v1 of the vacuum vessel 1 and the pressure P _v2 inside the vacuum cup 5 are both at the atmospheric pressure, and the spherical stopper 3 closes the exhaust port 2 by its own weight. When the evacuation starts, the pressure P _v2 decreases, and the pressure P _v1 > the pressure P _v2 , so that the spherical stopper 3 is separated from the exhaust port 2 by the pressure difference, and the evacuation of the vacuum vessel 1 is performed. As the evacuation continues, both the pressures P _v1 and P _v2 decrease. When the evacuation is stopped when the target pressure is reached, the pressure P
The pressure difference between _v1 and _Pv2 becomes small, and the spherical plug 3 blocks the exhaust port 2 by its own weight. Then the spherical plug 3 when this by the inside of the vacuum cup 5 to the atmospheric pressure removed from the vacuum vessel 1 by turning the 3-way stopcock 9 to the exhaust port 2 by a pressure difference between the atmospheric pressure P _a and the vacuum vessel pressure P _v1 It is pressed and vacuum-sealed.

[0009] The form of the exhaust port is not limited to a conical hole as shown in Fig. 1 and a spherical plug is combined, but the closing member enables exhaust from inside, and closes to the exhaust port by pressure from the outside. What is necessary is just to be a thing which closes. For example, even when the same spherical plug is used, an O-ring 4 is provided on the outer edge of the exhaust port 10 as shown in FIG.
May be sealed. In this case, the exhaust port 10 needs a counterbore on the outer surface side for accommodating the O-ring 4, but it goes without saying that the exhaust port 10 may be a simple cylinder at the back. In the method of FIG. 1 described above, the spherical stopper can be accommodated almost without protruding from the outer wall surface of the vacuum vessel, but this portion of the vacuum vessel needs a thickness in order to make the exhaust port conical. For this reason, it may be necessary to fit another material into the exhaust port as shown in FIG. On the other hand, FIG.
In the method (2), the spherical stopper protrudes from the outer wall surface of the vacuum vessel, so that the application is limited to the case where this does not become a hindrance. However, the thickness of the wall of the vacuum vessel is not so required.

Further, as an example of using a plug other than a spherical plug as a closing member, a cylindrical plug with a flange which is loosely inserted into a cylindrical hole 11 as a closing member as shown in FIG. A combination of 12 can also be used. In this case, an O-ring 13 is provided at the flange to maintain airtightness with the periphery of the exhaust port 11 of the vacuum vessel when pressure is applied from the outside. In this method, the exhaust port does not need to be functionally thick, and may simply have a hole. Therefore, it can be easily applied to a case where the wall thickness of the vacuum vessel is small.

In the exhaust method shown in FIGS. 1 to 3, the spherical stopper or the cylindrical stopper is sufficiently lifted up by the air flow at the start of the exhaust, and can be easily exhausted. Become smaller. For this reason, when a high degree of vacuum is required, it may take time to evacuate.In such a case, the plug is evacuated to another place during the evacuation and brought to the exhaust port when the evacuation is completed. Thereby, the conductance of the exhaust path can be favorably maintained.

FIG. 4 is a conceptual diagram showing an example of the above method, and FIG. 4A shows a state during evacuation. 21
Is a holder for holding the spherical plug 3 by a spring force, and holds the spherical plug at a position separated from the exhaust port 2 in the vacuum cup. Reference numeral 22 denotes a slidable push rod, which is connected to the inside and outside of the vacuum cup 5 through a vacuum-sealed hole 23. The push rod 22 is away from the spherical plug 3 and retracted during the exhaust.

FIG. 4B is a view showing a state after the evacuation is completed. The spherical plug 3 is separated from the holder 21 by being pushed by the push rod 22 and falls onto the exhaust port 2. In this method, it is preferable that the spherical stopper 3 is pressed against the exhaust port 2 by the push rod 22 and then the inside of the vacuum cup 5 is set to the atmospheric pressure to release the vacuum cup. In this way, the spherical plug 3 is pressed against the exhaust port 2 not only by its own weight but also by the force from the push rod 22 when exhaust is completed. Therefore, before air is put into the vacuum cup 5 and the spherical stopper 3 is strongly pressed against the exhaust port 2 at atmospheric pressure, there is no possibility that some air leaks into the vacuum container. In FIG. 4B, the three-way cock 9 shows a state when air is introduced into the vacuum cup.

In the above example, the holder 21 is the vacuum cup 5
It was provided in the form of being coupled to, but is not limited to such as long as it can hold the closing member at a position away from the exhaust port in the vacuum cup and can further move this to the exhaust port Absent. For example, a method in which a tripod is attached to a holder as shown in FIG. 4 may be placed on the exhaust port of the vacuum vessel. In addition, such a method of keeping the closing member away from the exhaust port during the exhaust is naturally applicable not only to the spherical stopper but also to a cylindrical stopper as shown in FIG.

Further, in the method of the present invention, in order to reliably maintain the degree of vacuum in the container for a very long period of time, after closing the container as described above, a further space is provided between the exhaust port and the spherical or cylindrical stopper. A vacuum sealant may be poured. For this purpose, a commercially available resin that solidifies by mixing two liquids or the like can be used as a vacuum sealant.

[0016]

Embodiments of the present invention will be described below. The vacuum vessel is SUS3 with a thickness of 2 mm and a circular exhaust port with a diameter of 5 mm.
800mm x 500mm made of 04 stainless steel
X Thickness of 50 mm. According to the method shown in FIG. 1, the vacuum cup was pressed to evacuate to 0.01 Torr, and the container was vacuum-sealed with a SUS304 material spherical stopper having a diameter of 8 mm. An O-ring made of butyl rubber is provided at a position where the spherical stopper of the exhaust port contacts. FIG. 5 shows a change in the degree of vacuum of the vacuum vessel over time after the evacuation of the vessel is closed. As can be seen from the results, the airtightness retention performance by the method of the present invention is excellent.

[0017]

According to the method for closing and evacuating a vacuum vessel of the present invention, the vacuum vessel can be evacuated at atmospheric pressure and then sealed without requiring a step of heating to a high temperature.
The present invention is applicable even if a substance that decomposes thermally is contained in the vacuum container. In addition, since the air is exhausted by pressing the vacuum cup against the exhaust port, the product can be manufactured without the exhaust pipe remaining in a state of protruding from the vacuum container of the product, and there is no possibility that the handling of the product or the design is restricted by the exhaust pipe. The method of the present invention allows for quick and low-cost evacuation of mass-produced products,
In particular, in the case of a large vacuum container such as a vacuum heat insulating panel, it is difficult to manufacture the vacuum container using a vacuum tank.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a plugging method according to the present invention.

FIG. 3 is a diagram showing an example of a plugging method according to the present invention.

FIG. 4 is a diagram illustrating an example of an exhaust gas plugging method according to the present invention.
(A) and (b) show the order of the steps.

FIG. 5 is a graph showing a change in the degree of vacuum of a vacuum container after vacuum closure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Exhaust port 3 Spherical plug 4 O-ring 5 Vacuum cup 6 Edge 7 O-ring 8 Exhaust pipe 9 3-way cock 10, 11 Exhaust port 12 Cylindrical plug 13 O-ring 21 Holder 22 Push rod 23 Hole

Claims (3)

[Claims] 1. A method for evacuation and closure of a vacuum vessel, wherein the vacuum vessel is closed after being evacuated, wherein an exhaust port is provided in the vacuum vessel, and a closing member which closes and closes the exhaust port with pressure from the outside is disposed on the exhaust port. Then, a vacuum cup having an edge for keeping airtightness with the plane around the exhaust port of the vacuum vessel and being connected to a vacuum pump is pressed against the plane of the vacuum vessel. A method for exhausting and closing a vacuum vessel, wherein the cup is brought into atmospheric pressure and removed, and the closing member is brought into close contact with an exhaust port by a pressure difference between the inside and the outside of the vacuum vessel. 2. A method for evacuation of a vacuum vessel, wherein the vacuum vessel is closed after the vacuum vessel is evacuated, wherein the vacuum vessel is provided with an exhaust port, and the vacuum vessel has an edge for maintaining airtightness with a plane around the exhaust port. And pressing the vacuum cup coupled to the vacuum pump against the flat surface of the vacuum container, and holding a closing member that closes and closes the exhaust port with pressure from the outside at a position away from the exhaust port in the vacuum cup; After the evacuation of the vacuum vessel is completed, the inside of the vacuum cup is brought to the atmospheric pressure and the vacuum cup is released while the closing member is pressed against the exhaust port, and the closing member is removed by the pressure difference between the inside and the outside of the vacuum vessel. A method for plugging and exhausting a vacuum vessel, characterized in that it is brought into close contact with the vacuum vessel. 3. A method for plugging and exhausting a vacuum vessel, further comprising the step of pouring a vacuum sealant between the exhaust port and the closing member after the step according to claim 1 or 2.