JP6378471B2 - Vacuum insulation panel - Google Patents

Description

  The present invention relates to a vacuum heat insulating panel suitably used for a refrigerator, a cold storage, a heat insulating wall, a heat insulating wall of a house, or the like, for example.

In recent years, energy-saving products and energy-saving technologies are being developed in various industries due to the power shortage. Vacuum insulation panels are products that have been developed as an energy-saving measure, and are currently widely used as insulation materials for refrigerators and vending machines in order to enhance insulation performance and reduce power consumption.
In addition, although examination of application as a heat insulating material for houses is underway, the current vacuum heat insulating panel has a structure in which a core material such as glass wool is heat sealed with an aluminum laminate film as shown in the left figure of FIG. The ones are common.

In the vacuum heat insulation panel with the structure heat-sealed with aluminum laminate film, moisture permeates from the heat-sealed part and the degree of vacuum is lowered, so adsorbents such as activated carbon and zeolite are enclosed, but still in 7-8 years There is a problem that the heat insulation performance is halved.
For this reason, development of the vacuum heat insulation panel which can maintain heat insulation over a long term is desired.
Therefore, for example, as shown in the right figure of FIG. 1, various vacuum heat insulating panels in which a core material such as glass wool is wrapped in a thin metal plate such as stainless steel and evacuated and then welded at the ends are proposed. ing. Various attempts have been made to make the structure easy to vacuum or vacuuming.

  Patent Document 1 proposes a method of evacuating by providing a groove for guiding and discharging air to one side of a metal outer packaging material that wraps the core material and an exhaust port connected to the groove. In this method, preliminary sealing around the groove and the exhaust port is performed by seam welding, plasma welding, or the like before vacuuming is performed in advance, and after the preliminary sealing, vacuuming is performed from the exhaust port through the groove. After the periphery is flattened with a press, etc., the groove that has been flattened by the same welding method as above is welded and completely sealed, and after sealing is completed, excess material is cut to produce a vacuum insulation panel. .

  Further, in Patent Document 2, a spacer (heat insulating material) having both a thick region and a thin region is inserted into a substantially flat space formed by upper and lower wrapping materials whose outer peripheral portions are welded and joined. While preventing the inner surface of the upper and lower packaging materials from contacting using the step generated in the meat region and the thin wall region, after evacuating from the exhaust port while securing the exhaust passage, the exhaust port is sealed, A vacuum insulation panel is manufactured by welding and joining the front of the exhaust port and then cutting the outside of the welded part.

JP 2009-228803 A Japanese Patent Laid-Open No. 2001-311497

As the welding method, various welding methods such as seam welding, TIG welding, laser welding, plasma welding, and the like are employed. In particular, when a stainless steel sheet is used as a material, a laser welding method in which distortion is hardly generated during welding is often employed.
However, when the laser welding method is employed, it is important to manage the gap between the two metal plates, and even if there is a slight gap between the metal plates, the melt-off easily occurs (see FIG. 2A). As the thickness of the material metal plate decreases, the frequency of occurrence of melting increases.
Therefore, the adoption of a seam welding method in which two metal plates are pressurized and welded while crushing a gap between the two metal plates has been studied. When a vacuum heat insulation panel is manufactured by the seam welding method, there is no gap due to the application of pressure, so that stable welding is possible (see FIG. 2B).

  When manufacturing a rectangular vacuum insulation panel by the seam welding method, as shown in FIG. 3 (a), it is conceivable to weld so as to form four weld lines, in which case the laps where the weld lines intersect are considered. Part will occur. In the cross section of each welding line, as shown in FIG.3 (b), the nuggets with substantially constant height are connected regularly. On the other hand, since the heating is performed twice in the lap portion, as shown in FIGS. 3C and 3D, the nugget grows excessively at the intersection of the two lines, and the nugget is not formed before and after. A part may arise or a blowhole and welding may arise near the intersection of two lines. It becomes easy to generate so-called welding defects. Further, the material metal plate is distorted by the influence of welding heat, and as shown in FIG. 3 (e), the flange portion may be wavy and flatness may be deteriorated. These problems become prominent when the plate thickness is thin.

When manufacturing vacuum insulation panels using the seam welding method, seam welding is performed in the vacuum chamber. However, when seam welding is continuously performed in the vacuum chamber, heat cannot be discharged to the outside, and the temperature of the electrode increases steadily. Will occur. This phenomenon is more likely to occur as the weld line length and the welding time become longer, and the welding portion becomes more heat input as the latter half becomes, and the above-described welding failure and distortion are increased. Moreover, since the temperature in the chamber rises as the temperature of the electrode rises, the function of the entire manufacturing facility is lowered, and the apparatus may not be used for a long time.
The present invention has been devised to solve such problems, and comprises a core material excellent in heat insulation and an enveloping metal plate excellent in gas impermeability covering its periphery, and the core After the inside of the outer metal plate that encloses the material is in a vacuum state, it is a vacuum heat insulating panel that is sealed at the outer periphery of the outer metal plate and has excellent durability, and the frequency of occurrence of defective welds is minimized An object of the present invention is to provide a vacuum heat insulating panel that is reduced and has a good flatness of the flange portion.

In order to achieve the object, the vacuum heat insulation panel of the present invention comprises a heat-insulating core material and two enveloping metal plates covering the periphery thereof, and the two enveloping metal plates enclosing the core material. It is a vacuum heat insulation panel in which the inside is in a vacuum state and the outer peripheral metal plate peripheral edge is joined by seam welding, and the solid state joint and the melt joint are regularly repeated over the entire length of the weld It is characterized in that a part of the welded portion intersects and a part where the welded portion intersects is the solid phase joint .
As the enveloping metal plate, a stainless steel plate is preferable, and in particular, a ferritic stainless steel plate is used at least on one side.

In the vacuum heat insulation panel of the present invention, a seam welding current is used as a method for joining the peripheral portion of the outer metal sheet during the production thereof, and the nugget is not continuously connected and the nugget is solid-phase joined. Is seam welded under the condition of intermittent flow.
For this reason, the sealing at the outer peripheral metal plate peripheral portion of the vacuum heat insulating panel is performed by welding joining in such a form that the formation of the nugget is suppressed as much as possible or the formed nugget is minimized. No bonding failure occurs during the second bonding. Moreover, since the amount of heat input is generally small, distortion of the material metal plate due to the influence of welding heat is suppressed, and a vacuum heat insulating panel with excellent flange flatness is obtained.
With such a synergistic effect, a high-performance vacuum insulation panel can be provided at a low cost.

Schematic explaining the structure of the vacuum insulation panel Diagram explaining the difference between laser welding and seam welding Diagram explaining problems in manufacturing vacuum insulation panels by seam welding Diagram explaining the difference between melt bonding and solid phase bonding A diagram for explaining a joining state in which fusion joining and solid-phase joining are regularly repeated The figure explaining the pulse energization form at the time of seam welding The figure explaining the member structure of the vacuum heat insulation panel produced in the Example The figure explaining the welding process of the vacuum heat insulation panel produced in the Example The figure explaining the joining form in an Example The figure which shows the schematic structure of the apparatus used for preparation of the vacuum heat insulation panel in an Example.

As described above, in order to manufacture a vacuum insulation panel that covers a core material excellent in heat insulation with an outer metal plate excellent in gas impermeability and can maintain the inside in a high vacuum state for a long time, It is necessary to wrap the core material with a wrapping material such as a thin metal plate such as stainless steel, and after evacuation, the ends are welded together. When the seam welding method is employed as the welding method, the above-described welding failure occurs or the flatness of the flange portion deteriorates. Moreover, the function of a manufacturing apparatus falls by the influence of welding heat, and it becomes impossible to perform continuous operation for a long time.
Therefore, the inventors of the present invention have reached the present invention in the process of intensively studying a method capable of sealing and joining after simply evacuating from the overlapping surface of the packaging material.
Details will be described below.

In the seam welding method, an electric current is caused to flow between metals to be joined to cause resistance heating, and the heat is used to melt and join.
When manufacturing a rectangular vacuum heat insulation panel using such a seam welding method, the crossing of a welding line is inevitable. When the second seam welding current is passed at this intersection, the welding current is shunted due to the influence of the nugget formed during the previous seam welding, and welding failure such as nugget non-formation, blowhole, or welding occurs. Conceivable. That is, it is thought that the nugget formed by the fusion welding method called seam welding contributes to the occurrence of poor welding during the next seam welding.

Therefore, if bonding is performed so as to suppress the formation of the nugget as much as possible or so that the formed nugget is as small as possible, it can be assumed that no bonding failure occurs during the second bonding. As shown in FIG. 4, solid phase diffusion bonding in which the interface is bonded by diffusion of atoms in the solid phase region by performing heating with low heat input instead of heating with high heat input such as fusion bonding may be employed. It is.
Repeated various preliminary experiments, and in the case of vacuum insulation panels, if they are sufficiently joined, solid-phase joining will exhibit the same strength as melt joining and should be sufficient in the case of vacuum insulation panels. confirmed.

However, in the case of performing solid phase bonding that exhibits sufficient bonding strength with low heat input, it is necessary to strictly adjust the amount of heat input depending on the material and thickness of the metal plate to be bonded. If the amount of heat input is too large, the seam welding will result in a joined state in which the nugget is connected. Conversely, if the amount of heat input is too small, solid phase bonding will not produce sufficient strength.
Therefore, in the present invention, the entire length of the welded portion is not joined by solid-phase joining, but sufficient joining strength is obtained by the joining state in which the solid-phase joining portion and the fusion joint portion are regularly repeated. It is a thing.

  In order to obtain a joint state in which the solid-phase joint and the melt joint are regularly repeated over the entire length of the weld, the welding current may be intermittently supplied at a constant welding speed. As shown in FIG. 6, by selecting a condition in which the nugget can be formed as pulsed energization and the nugget is not continuously connected, the nugget is formed in the energized area and the energized area is off. Solid phase bonding is performed by residual heat during nugget formation. If welding is performed by this method, the total heat input can be kept low compared to the conventional melt bonding conditions in which nuggets are continuously formed.

  In addition, in the joint state in which the solid-phase joint and the melt joint are regularly repeated, the lower the proportion of the melt joint in the total length of the weld, the lower the amount of heat input, and the problems of thermal distortion and poor welding of the lap part, etc. Can be avoided. However, the appropriate current range tends to be narrowed under the condition where the ratio of the melt-bonded portion in the entire length of the welded portion is 40% or less. In addition, if the ratio of the melt-bonded part in the entire length of the welded part exceeds 90%, the solid-phase jointed part will become extremely small, so it becomes a form close to the conventional melt-joined condition and the above-mentioned thermal strain and poor welding of the lap part There is also a risk of problems. For this reason, it is preferable to adjust the ratio of the melt-bonded portion in the entire length of the welded portion so as to be within a range of 50 to 90% in which conditions can be easily set and there is little risk of thermal distortion or poor welding.

By adopting the present invention, an austenitic stainless steel plate is used for the processed part side material that forms the core material containing part by drawing or overhanging, and a ferritic stainless steel sheet is used for the non-processed part side material that covers the core material containing part. Even if it is the vacuum heat insulation panel used, the vacuum heat insulation panel which does not have poor welding and was excellent in the flatness of a flange part can be provided stably and at low cost.
In particular, even in a portion where the welding lines intersect, the nugget is not formed or is fine even if it is formed during the first seam welding. Accordingly, since the welding current is not diverted during the second seam welding, a vacuum heat insulation panel free from welding defects can be provided.
Furthermore, since the amount of heat input during welding is relatively small, the flatness of the flange portion due to welding thermal distortion is not deteriorated.

Production Example 1;
The member structure of the vacuum heat insulation panel created in FIG. 7 is shown. SUS430 and SUS304 steel plates with dimensions of 220 mm × 220 mm × 0.1 ^t mm were used for the upper and lower packaging materials covering the core material. On the SUS304 side, a bulging portion of 190 mm × 190 mm × 5.0 mm was prepared by overhanging for containing the core material.
Then, a glass wool core material of 180 mm × 180 mm × 5.0 mm was accommodated in the bulging portion of the lower SUS304 packaging material and overlapped with the upper SUS430 packaging material.
In a state where the upper and lower packaging materials are held under pressure, first, as shown in FIG. 8 (a), the flange peripheral portions of the upper and lower packaging materials are welded by seam welding except for some openings. To do. The seam welding machine used at this time was a single-phase AC type, and the upper electrode was disk-shaped, the lower electrode was rod-shaped and the upper electrode was welded while rotating over the lower electrode. For the upper and lower electrodes, electrodes with the same tip shape and a width of 4mm and a curvature of 20R are used. Welding conditions are pressure: 150N, welding speed: 1m / min, welding current: 1.2kA, energization time on / off : 3/2 ms, and as shown in FIG. 9A, the ratio of the melt-bonded portion to the total length of the weld was 50%, and the ratio of the solid-phase bonded portion was 50%.

  In the subsequent sealing in the second step, an apparatus including the same seam welding machine used in the first step in the vacuum chamber shown in FIG. 10 was used. This equipment is also equipped with a work table for fixing the work in the chamber, and the panel that has been previously welded is fixed to this work table, and vacuuming is performed until the degree of vacuum in the chamber becomes 2 Pa or less. went. At this time, the degree of vacuum inside the panel is estimated to be almost the same as the degree of vacuum in the vacuum chamber because the internal air is forcibly exhausted through the panel opening. After reaching the target degree of vacuum, the welding start portion and end as shown in FIG. 8 (b) using the seam welder described above for the opening that was unwelded in the first step as shown in FIG. Each part was welded and sealed so as to wrap with the weld in the first step.

Production Example 2;
Subsequently, a method of manufacturing a vacuum heat insulation panel made of stainless steel plate using SUS304 materials as upper and lower packaging materials will be described.
The upper and lower wrapping materials that cover the core material are SUS304 stainless steel plates with dimensions of 220 mm x 220 mm x 0.1 ^t mm, and one wrapping material is formed by overhanging a 190 mm x 190 mm x 5.0 mm bulge to accommodate the core material. It was produced by.
Then, a glass wool core material of 180 mm × 180 mm × 5.0 mm was accommodated in the bulging portion of the packaging material, and the upper and lower packaging materials were overlapped.

A vacuum heat insulation panel is manufactured by welding in the first step in the atmosphere and sealing in the second step in the chamber in the same manner as in Production Example 1. The shape of the upper and lower electrodes used at this time and the welding conditions were changed. A flat electrode with a width of 4 mm was used on the upper side of the electrode, and an electrode with a width of 4 mm and a curvature of 20 R was used on the lower side. Welding conditions were as follows: welding pressure: 150 N, welding speed: 1.2 m / min, welding current: 1.6 kA, energization time on / off: 3/2 ms, as shown in FIG. The ratio was 90%, and the ratio of the solid phase junction was 10%.
A vacuum heat insulating panel made of a stainless steel plate was produced by the method described above.

None of the vacuum heat insulation panels produced by the two methods described above had poor welding at the flange portion, the flatness of the flange portion was good, and no overall shape change was observed.
In Production Example 2, two austenitic stainless steel plates were used, and the austenitic stainless steel plates were joined to form a vacuum heat insulating panel. However, as confirmed in Production Example 1, an austenitic stainless steel plate excellent in drawing workability, Even if a relatively inexpensive ferritic stainless steel sheet is used, it has become possible to produce a vacuum heat insulation panel that is solid-phase bonded at the flange without any problem.

Claims (4)

It consists of a core material having heat insulation properties and two enveloping metal plates covering the periphery thereof, and the inside of the two enveloping metal plates enclosing the core material is in a vacuum state, and the periphery of the enveloping metal plate is a seam A vacuum insulation panel joined by welding ,
Has become over the entire length of the welded portion with the solid joint between the bonding state of fusion bonding portion is regularly repeated, sites a part of the weld cross, a portion of the weld intersect the A vacuum heat insulation panel characterized by being a solid phase junction .   The vacuum heat insulation panel according to claim 1, wherein the ratio of the melt-bonded portion in the entire length of the welded portion is in the range of 50 to 90%.   The vacuum heat insulation panel according to claim 1 or 2, wherein a stainless steel plate is used as the outer metal plate.   The vacuum heat insulation panel according to claim 3, wherein a ferritic stainless steel plate is used on one side of the outer metal plate.

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