KR20170050127A - Refrigerator - Google Patents

Abstract

The present invention provides a refrigerator, to which a vacuum insulator is applied, while being reliably operated, and a method for manufacturing the refrigerator. According to the present invention, a vacuum spatial part having a temperature between the temperature of an internal space and the temperature of an external temperature and formed in a vacuum state is provided. A conduction resistant sheet capable of resisting thermal conduction between a first plate member and a second plate member is included. The conduction resistant sheet and at least one of the plate members are welded to provide a welding part, and a plurality of regular beads are provided onto the surface of the welding part. Each of the beads comprises: a parabola-shaped knee curve region provided to a central part; a linear region provided to both outer sides of the knee curve region; and an edge region provided to the outside of the linear region.

Description

Refrigerator {Refrigerator}

 The present invention relates to a refrigerator. More specifically, it relates to a refrigerator in which a vacuum insulator is used.

It has been a common practice to provide a foamed polyurethane insulating wall having a thickness of more than about 30 centimeters, although the insulation method applied to conventional refrigerators differs depending on refrigeration and freezing. However, there is a problem that the internal volume of the refrigerator is reduced.

There is an attempt to apply a vacuum insulator to the refrigerator to increase the internal volume of the refrigerator. The vacuum heat insulator is provided with a vacuum space portion having a vacuum inside to reduce the heat transfer amount. For example, Korean Patent Application No. 10-2015-0109624 filed by the applicant of the present invention discloses a refrigerator to which a vacuum insulator is applied. The above citation document discloses a structure in which a conductive resistance sheet is interposed between the first plate member and the second plate in contact with the inner and outer spaces of the refrigerator to provide a vacuum insulation body. The conductive resistance sheet is thin to resist thermal conduction between the first plate and the second plate.

The conductive resistance sheet is provided several ten times thinner than the plate to resist heat conduction. In order to provide the vacuum space part in a vacuum state, the coupling parts of the conductive resistance sheet and the plate member must be sealed. In other words, the plate member and the conductive resistance sheet having a significantly smaller thickness than the plate member must be tightly sealed with each other. As a method of satisfying this condition, it is preferable to weld the conductive resistance sheet and the fastening portion of the plate to each other.

Welding between the plate and the conductive resistance sheet is considerably difficult due to the difference in thickness between the plates. For example, even if the distance between the two members is very small, even if the thin conductive resistance sheet is melted, the plate member (hereinafter also referred to as a plate) does not melt or the melt can not fill the gap between the two members There is a problem that the conductive resistance sheet and the plate are not brought into contact with each other. Such a problem may occur at all points where the plate and the conductive resistance sheet are in contact with each other, and even if a sealing failure occurs at a certain point in the welded portion, the vacuum heat insulator as a whole can not be used as a defect.

Description of welds in Korean Patent Application No. 10-2015-0109624

 The present invention has been proposed under the above-mentioned background, and the inventors have made various attempts and efforts to accomplish the present invention in order to perform welding sealing between the conductive resistance sheet and the plate. More specifically, the present invention proposes a refrigerator which can secure mutual perfect fusion performance with respect to all fusing points of a plate and a conductive resistance sheet, and can stably maintain a seal so that leakage does not occur at any particular point, do.

A refrigerator according to a first aspect of the present invention includes: a main body provided with an internal space capable of storing a stored product; And at least one of the body and the door includes a vacuum insulation body, and the vacuum insulation body is provided with at least a part of the wall for the interior space A first plate member defining a first plate member; A second plate member defining at least a portion of a wall for said outer space; And a vacuum space part which is a space between the temperature of the inner space and the temperature of the outer space and is a vacuum space, and a conductive resistance sheet capable of resisting thermal conduction between the first plate member and the second plate member Wherein at least one of the conductive resistance sheet and the plate member is welded to each other to provide a weld, wherein a surface of the weld is provided with a plurality of regular beads, and the bead is provided with a parabolic- ; A linear region provided on both sides of the bent region; And an edge area provided outside the linear area.

Preferably, the angle formed by the linear region with the welding direction is 9 to 43 degrees.

Preferably, the number of the beads is 20 to 100/1 mm based on the welding direction, and the beads may be regularly provided.

Preferably, the thickness of the plate member to be melted to be provided to the welded portion is 0.1 to 3 times the thickness of the thin plate.

Preferably, the welding is performed by laser welding, wherein the control conditions of the laser welding are a beam size of 200 to 375 占 퐉, a laser moving speed of 7 to 15 m / min, and an output of 200 to 800 W.

A refrigerator according to a second aspect of the present invention includes: a body provided with an internal space capable of storing a stored product; And at least one of the body and the door includes a vacuum insulation body, and the vacuum insulation body is provided with at least a part of the wall for the interior space A first plate member defining a first plate member; A second plate member defining at least a portion of a wall for said outer space; And a vacuum space part which is a space between the temperature of the inner space and the temperature of the outer space and is a vacuum space, and a conductive resistance sheet capable of resisting thermal conduction between the first plate member and the second plate member Wherein at least one of the conductive resistance sheet and the plate member is welded to each other to provide a weld, wherein the weld is performed by laser welding in a thermal conduction mode, and the thickness of the plate member, which is melted in the weld, To about 3 times as large as that of the substrate.

Preferably, in order to provide the weld, the laser movement speed is 7 to 15 m / min and the output is 200 to 800 W.

Preferably, the beads provided on the surface of the welded portion may include at least a linear region.

Preferably, the conductive resistance sheet is 10 to 200 micrometers, and the plate member is 500 to 2000 micrometers, wherein the plate member may be provided at a thickness of 10 to 100 times the conductive resistance sheet.

 According to the present invention, it is possible to provide a refrigerator capable of performing a reliable operation while a vacuum insulator is applied.

1 is a perspective view of a refrigerator according to an embodiment;
2 is a view schematically showing a vacuum insulator used in a main body of a refrigerator and a door.
3 is a configuration diagram of a refrigerator manufacturing apparatus used for manufacturing a refrigerator.
4 is an exploded perspective view of the jig.
5 is a cross-sectional view showing a periphery of a groove enlargedly displayed.
6 is a plan view for observing a welded portion while a welding process is being performed;
7 is a cross-sectional view taken along line I-I 'of Fig. 6;
8 is a table showing results of leakage tests and fracture tests performed on the specimens obtained after welding.
9 is a view showing the shape of a solidified portion when the width and thickness of the fused portion are large.
11 is a diagram showing a shape of a solidified portion as a result of an experiment while changing the laser output and the moving speed of the laser with a laser beam size of 200 mu m.
12 is a graph showing the energy per unit area and the depth of a weld.
13 is a view showing a result of testing depth and tensile strength of a welded portion.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims, Or the like, but it will also be included within the scope of the present invention.

The drawings shown below may be displayed differently from the actual product or exaggerated or simple or detailed parts may be deleted, but this is intended to facilitate the understanding of the technical idea of the present invention, and the size, structure and shape It should not be construed as limited.

1 is a perspective view of a refrigerator according to an embodiment.

Referring to FIG. 1, a refrigerator 1 includes a main body 2 provided with a cavity 9 capable of storing a stored product, and a door 3 provided to open and close the main body 2. The door 3 is rotatably disposed or slidably movable so that the cavity 9 can be opened and closed. The cassette 9 may provide at least one of a refrigerating chamber and a freezing chamber.

The refrigerator is provided with a component constituting a refrigeration cycle for supplying cold air to the cavity. A condenser 5 for condensing the compressed refrigerant; an expander 6 for expanding the condensed refrigerant; and an evaporator 7 for evaporating the expanded refrigerant to depressurize the refrigerant. ). As a typical structure, a fan may be installed at a position adjacent to the evaporator 7, and the fluid blown from the fan may be blown to the cavity 9 after passing through the evaporator 7. It is possible to control the refrigerating space or the freezing space by adjusting the blowing amount and the blowing direction by the fan, adjusting the amount of the circulating refrigerant, or adjusting the compression ratio of the compressor to adjust the refrigerating load.

FIG. 2 is a view schematically showing a vacuum insulator used in a main body of a refrigerator and a door, in which a vacuum insulator of a main body side is shown with its top and side walls removed, Fig. In addition, the cross section of the portion where the conductive resistance sheets 60 and 63 are provided is schematically shown to facilitate understanding.

Referring to Figure 2, the vacuum insulation comprises a first plate member 10 providing a wall of a low temperature space, a second plate member 20 providing a wall of a hot space, And a vacuum space part 50 defined by an interval between the first plate member 20 and the second plate member 20. And conductive resistance sheets 60 and 63 for preventing heat conduction between the first and second plate members 10 and 20 are included. There is provided a weld portion 61 for sealing the first plate member 10 and the second plate member 20 in order to bring the vacuum space portion 50 into a closed state. When the vacuum insulator is applied to a refrigerator or a hot plate, the first plate member 10 may be referred to as an inner case, and the second plate member 20 may be referred to as an outer case. A machine room (8) in which a component for providing a refrigeration cycle is placed is located on the lower rear side of the vacuum insulator on the main body side, and a vacuum state is created by evacuating the air in the vacuum space part (50) An exhaust port 40 is provided. In addition, a duct 64 may be further provided to pass through the vacuum space part 50 for installation of the demolition water and the electric wire.

The first plate member 10 may define at least a part of the wall for the first space provided on the first plate member side. The second plate member 20 may define at least a part of the wall for the second space provided on the second plate member side. The first space and the second space may be defined as spaces having different temperatures. Here, the wall for each space may function not only as a wall directly contacting the space but also as a wall not contacting the space. For example, a vacuum insulator of the embodiment can be applied to an article having a separate wall adjacent to each space.

The thermal insulation between the first plate member 10 and the second plate member 20 may be caused by heat conduction between the first plate member 10 and the second plate member 20, And the gas conduction of the vacuum space portion 50. [ The heat conduction between the first plate member 10 and the second plate member 20 can be blocked by the conductive resistance sheets 60 and 63. [ The conductive resistance sheets 60 and 63 are fastened to the plate member 10 or 20 or the side frame 70 by the welding portion 61 so that the welding portion 61 is completely sealed, The vacuum state of the portion 50 can be maintained. The plate members 10 and 20 and the side frame 70 function as a base member to which the conductive resistance sheets 60 and 63 provided as thin metal plates are welded, . Likewise, the conductive resistance sheets 60 and 63 may be called thin plates. For example, the thin plate may be 10 to 200 mu m, and the base material may be 500 to 2000 mu m. Preferably, the base material may have a thickness of 10 to 100 times the thickness of the thin plate. This is to obtain an effect on the thermal conduction resistance.

In the embodiment, the inside of the vacuum space part 50 can be stably and completely sealed by the welded part 61. For this, the welded portion 61 should be kept sealed so that there is no leakage, and it should have a strength enough to withstand the stress caused by the vacuum pressure of the vacuum space portion 50.

The characteristics of the welded portion 61 can be achieved by constituting an apparatus for providing a welded portion. In order to stably and stably provide the welded portion, the following three problems can be cited. First, the jig that makes the laminate and the base material come in close contact with each other does not function properly. For example, when the flatness of the jig is uneven and the gap between the thin plate and the base material is not entirely pressed, it is difficult to completely adhere the thin plate to the base material. In this case, only the thin plate is melted by the laser and the base material is not melted, It can cause leakage. Second, when the surface of the thin plate and the base material is rough or scratchy, the laser irradiation is poor, so that it can not be fused locally, or the melt can not fill the gap, resulting in welding failure. Third, in the case where foreign matter such as dust is present on the fused surface of the thin plate and the base material, the foreign matter is burned by the laser, and the melting liquid is boiled or the incompletely combusted material is mixed with the molten liquid.

The performance of the welded portion 61 may vary depending on the characteristics of the laser irradiated from the head 104 together with the welded portion. For example, if the irradiation amount of the laser is large, the thin plate and the base material may melt in a large amount to weaken the strength of the fused portion, and if the moving speed of the laser is high, Is high, the volume of the fused portion becomes large, which is not preferable.

Hereinafter, a refrigerator manufacturing apparatus provided to solve the above problems will be described.

3 is a configuration diagram of a refrigerator manufacturing apparatus used for manufacturing a refrigerator, and more particularly, a configuration diagram of an apparatus for providing the welding section.

3, the refrigerator manufacturing apparatus includes a jig 100 on which the conductive resistance sheets 60 and 63, the plate members 10 and 20 and the side frames 70 are supported, A vacuum pump 102 for applying a vacuum to the jig 100 and an inert gas source 103 for applying an inert gas to the jig 100 are included. A multimode fiber laser of 2 kW class can be used as the laser source 101, and a laser can be applied to the thin plate and the base material through the head 104. The inert gas source 103 may introduce an inert gas into a portion irradiated with a laser beam through the nozzle 105 using a predetermined channel.

In the examples, argon was used as the inert gas. Further, the spraying angle of the nozzle 105 was 45 degrees, the height between the nozzle 105 and the laser irradiation point was 6 mm, and the diameter of the nozzle 105 was 8 mm. The inert gas prevents the burning of the foreign matter and suppresses the oxidation phenomenon, thereby preventing the weld defect.

It is important that the laser source 101 and the head 104 are capable of irradiating a laser beam capable of fusing the thin plate and the base material. As the laser control means capable of achieving this object, the output of the laser, the irradiation area of the laser, and the moving speed of the radar, that is, the moving speed of the head, may act as a regulating factor of the laser as a heat source.

4 is an exploded perspective view of the jig.

Referring to FIG. 4, the jig 100 includes a base 110 and covers 113 and 114. Between the base 11 and the covers 113 and 114, a base material 111, (112) can be placed. In other words, the base 113 and the thin plate 112 can be positioned on each other at a proper position where the base 111 is to be welded to each other, and the covers 113 and 114 can cover the base 111 and the thin plate 112, respectively.

A groove 115 is provided in the base 11 and vacuum pressure from the vacuum pump 102 can be applied through the groove 115. The groove 115 is provided with a thin plate 112 to provide a downward pulling force when the thin plate 112 is viewed from the drawing. A base material 111 is provided on the lower side of the thin plate 112. The base material 111 may be provided with an inner base material 111b and an outer base material 111a welded to the inside and the outside of the thin plate 112 have. The inside base material 111b and the outside base material 111a are spaced apart from each other and the thin plate 112 can be placed in a structure that covers the space therebetween. Accordingly, the thin plate 112 can be subjected to negative pressure applied through the groove 115. The inner plate 111b may be a first plate member 10 and the outer plate 111b may be a second plate member 10, for example. An inner elastic body cover 113b and an inner rigid cover 114b are provided as a cover for pressing a portion where the inner base material 111b and the thin plate 112 overlap. An outer elastic cover 113a and an outer rigid cover 114a are provided as a cover for pressing a portion where the outer base material 111a and the thin plate 112 overlap. Referring to the above configuration, it can be seen that welding is performed to the outside and inside, respectively, and the welding can be performed at one time using the two heads 104. In this case, the working efficiency can be improved.

Vacuum pressure is applied to the thin plate 112 through the groove 115 so that the thin plate 112 can adhere perfectly to the base material 111. In other words, the negative pressure applied through the groove 115 can pull the thin plate 112 to bring the thin plate into close contact with the base material 111. Therefore, a gap that may occur between the thin plate 112 and the base material 111 can be prevented by the local deformation or the numerical problem of the thin plate 112 or the base material 111. The foreign matter such as dust is removed between the thin plate 112 and the base material 111 due to the strong flow generated by the negative pressure, so that the foreign matter may not interfere with the welding.

Further, the thin plate 112 and the base material 111 can be more tightly contacted by the even pressing force of the elastic body cover 113. This will be described in more detail below.

The cover 113 and 114 are provided with a rigid cover 114 for applying a generally pressing force to the cover 113 and a cover 114 for holding the rigid cover 114 under the force of the rigid cover 114, (112). The elastic cover 113 may be made of PDMS or rubber, and may be provided as an O-ring instead of a rectangular shape as shown in the figure. The elastic cover 113 is appropriately deformed along the entire shape of the base material 111 and the thin plate, and the thin plate 112 can evenly be pressed. Here, the overall shape is to focus on observing the height difference in the up-down direction, that is, the pushing direction as a whole, with reference to the drawing. Therefore, the degree of contact between the thin plate 112 and the base material 111 can be further improved. The elastic cover 113 is deformed along the entire shape of the base material 111 which is not deformed without a certain level of force so that the thin plate 112 can be brought into close contact with the base material 111 .

An advantage that the rigid cover 114 is not replaced by the elastic cover 113 can be obtained. In particular, since the small scratches of the rigid cover 114 can also affect the close contact between the thin plate and the base material, the rigid cover 114 can cause scratches on the surface due to repeated use, There is a need. However, since the elastic cover 113 is soft and does not generate scratches and is deformed by itself even in the presence of scratches, there is no problem in contact between the base material and the thin plate.

It is more preferable that the elastic cover 113 is provided in a structure that entirely surrounds the welded portion. In other words, it is possible to prevent welding failure to a small portion of the welded portion 61 by supporting the outside of the thin plate 112 with the constitution of a closed curve which surrounds the whole. The closed curve may be provided in the form of a thick curved surface so as to improve the sealing performance. For example, the entire area of the thin plate 112 can be pressed by the elastic body cover 113 from one direction to the other end of the welded portion.

The thin plate 112 can be more closely adhered to the base material 111 by the vacuum pressure applied through the groove 115 as the thin plate 112 and the base material 111 are mechanically brought into close contact with each other by the elastic cover 113. [ have. At this time, even if there is a slight gap between the thin plate 112 and the base material 111, the thin plate 112 is further brought closer to the base material 111 side by the static pressure of the strong flow velocity of the outside air flowing through the interval So that the distance between the thin plate 112 and the base material 111 is substantially equal to the distance from the weld.

Fig. 5 is a cross-sectional view showing an enlarged view of the periphery of the groove, and the operation of the refrigerator manufacturing apparatus according to the embodiment will be described in more detail.

5, the thin plate 112 serving as the conductive resistance sheets 60 and 63 is placed in the gap 115 of the base material 111 with the curved surface portion provided to elongate the heat conduction path, So that the welding can be performed. The welding portions 61 may be provided on both sides of the thin plate 112, respectively. It can be easily guessed that the welding portion 61 can be provided long in the vertical direction of the paper surface.

A vacuum force is applied from the vacuum pump 102 to the groove 115, so that a downward force is generated on the surface of the thin plate 112 with reference to the drawing. The arrow indicates the force received by the lamella 112. The force applied to the thin plate 112 causes a force to pull both ends of the thin plate 112 toward the center. The direction of the arrow indicates the force applied to both ends of the thin plate. This force acts as a factor causing weld failure during welding. The drawing will be described in more detail by changing the drawing.

6 is a plan view for observing the welded portion while the welding process is being performed.

6, when a heat source such as a laser is moved relative to a thin plate and a base material and welding is performed, a section where the thin plate 112 and the base material 111 melt by the heat source to become a melt, (112) and the base material (111) are fixed to each other. In the drawing, a molten portion 611 having a melt to be fused and a solidifying portion 612 provided to solidify the molten portion 611 are displayed on the basis of the traveling direction of the heat source. The molten portion 611 may be provided with a predetermined length l as a portion where the molten liquid is supplied in a liquid state. However, the fused portion 611 can not support the pulling force from the left and right sides of the fused portion 611, and the other portions, that is, the portions that have not yet melted, and the fused portion 612 must support the fused portion 611.

In other words, in the interval 1 between the molten portions 611, a force for causing the molten portion 611 to spread is generated by the vacuum pressure of the groove 115. When the molten solder 611 spreads in the left and right directions with reference to the drawing, the molten solder 611 generates a non-uniform flow of the molten liquid, thereby causing a locally unfused portion or an empty gap, Can act as a factor. Of course, the fused portion 611 may be supported indirectly by the solidified portion 612 and the non-welded portion without being flared, but this depends on the entire length of the fused portion 611. For example, if the length (1) of the molten solder 611 is very small, the solder may be slightly worn and not affect the welding performance. However, if the length 1 of the molten solder 611 is considerably long It will not be able to ignore the length of its spread.

7 is a cross-sectional view taken along line I-I 'of Fig.

Referring to FIG. 7, the solidified portion 612 has a different physical property from that of the thin plate 112 and the base material 111, and has a lower strength than that of the thin plate and the base material . Therefore, it is preferable that the thickness of the solidified portion 612 is as thin as possible, because of the relationship between the thickness t1 of the thin plate 112 and the thickness t2 of the solidified portion. However, when a weak output laser is used to provide the thickness of the solidified portion 612 thinner, it is not preferable because a portion that is not fused locally may occur. The control of the laser capable of achieving the above object will be described later. The solidified portion 612 is substantially the same as the welded portion 61 and the solidified portion 612 is a welded portion after the solidified portion 611 is solidified.

Referring again to FIG. 5, a force for causing the welding portion 61 to spread in the left-right direction in the molten portion 61 and a structure provided to resist the force will be described in detail. A force of pulling toward the center in the welded portion 61 is generated in the thin plate 112 by the vacuum pressure. It can be seen that the pulling force is proportional to the length L of the curved portion of the thin plate 112 which receives the vacuum pressure. As a force corresponding to this force, a static frictional force generated in the interval from the welded portion 61 to the distal end portion of the base material 111 is generated. If the static friction force is larger than the pulling force by the vacuum pressure, welding failure by the fused portion 611 does not occur.

The frictional force may be proportional to the pressure at which the thin plate 112 presses the base material 111 and the distance D from the weld 61 to the front end of the base material 111. [ The pressure between the thin plate and the base material may correspond to the difference between the pressure between the two members and the atmospheric pressure. Therefore, when the both ends of the thin plate 112 are completely closed by the elastic body cover 113, the fluid pressure can be increased by the vacuum pressure of the groove 115 without fluid flow, Can be applied to an interval portion between the thin plate and the base material. Therefore, the frictional force can be increased as the distance D between the welded portion 61 and the tip of the base material 111 becomes longer. However, when the vacuum insulator is provided with a refrigerator, it acts as a factor for increasing the heat transfer amount between the base material 111 and the thin plate 112, which is not preferable.

Under the circumstances described above, the inventors performed various experiments. In the above-mentioned experiment, the airtightness test for judging whether leakage occurred was judged as leakage to a vacuum of 10 ^-11 torr and whether there was leakage only when there was no leakage at both times Respectively.

Table 1 shows the experimental results.

L (mm) D (mm) L / D quality 2 8 0.25 Leakage 2 6 0.33 Leakage 3 8 0.38 Leakage 3 6 0.5 Leakage 4 8 0.5 Leakage 4.5 8 0.56 Leakage 5 8 0.63 Good 4 6 0.67 Good 4.5 6 0.75 Good 5 6 0.83 Good 5.5 6 0.92 Good

Referring to Table 1, when the length (D) of the portion where the frictional force acts / the length L of the portion to which the vacuum pressure is applied is not less than a predetermined level, that is, 0.6 or more, I could confirm. The length of the portion to which the frictional force acts may be defined as a distance from the welded portion 61 to the end of the base material 111. The length of the portion to which the vacuum pressure is applied is exposed to the vacuum space portion, And the length of the thin plate that is received. On the other hand, as described above, if the length D of the portion where the frictional force is applied is made long, there is a problem that the heat conductivity increases and the heat loss increases after the refrigerator adopting the vacuum insulator is manufactured. The length (D) of the portion / the length (L) of the portion to which the vacuum pressure is applied is preferably limited to a maximum of 1. According to the experiment, more preferably, D / L can be provided in the range of 0.63 to 0.92.

On the other hand, when providing the welded portion 61, it is preferable that the welding mode is provided in the heat conduction mode. In detail, the welding mode for laser welding includes a thermal conduction mode and a keyhole mode. First, in the conduction mode welding, the depth of the material to be melted is relatively shallow and the width of the portion where the melted portion is wider than the depth, and in this case, the power density is relatively low. The keyhole mode welding or beam hole is a mode in which the power density of the laser is higher than a certain limit so that evaporation of the material becomes vigorous and a keyhole is formed in the molten material due to the reaction force caused by the metal vapor pressure, The inside of the material is heated directly, so that deep melting can be obtained.

In order to shorten the length of the melted portion 611 and reduce the spread of the molten portion 611, it is preferable that the welded portion 61 is provided in a heat conduction mode.

As a laser control condition capable of achieving the object of achieving the above-mentioned heat conduction mode and constituting the stable welded portion 61, the laser output, the irradiation area of the laser, the moving speed of the radar, The speed can act as a modulator of the laser as a heat source.

Experiments were performed in various cases by varying the laser irradiated from the head. Hereinafter, results of experiments will be described.

8 (a) and 8 (b) show the results of performing leakage tests and breaking tests on the specimens obtained after welding, respectively. FIG. 8 (a) And the results are shown in Fig.

Referring to FIG. 8, X denotes leakage or breakage, wherein the leakage refers to the mass of gas passing through the welded portion in a vacuum state, and the fracture occurs in the specimen including the welded portion 61 during the test of tensile strength Indicating that the weld has broken. It was confirmed that the welded portion was broken at the tensile strength of about 1000 MPa. ○ indicates that welding or welding has failed because no leakage or breakage has occurred.

The experiment was carried out in the following cases. First, the beam sizes were 200 μm, 375 μm, 625 μm, and 1125 μm. The output was varied from 100W to 2000W. The traveling speed of laser was varied from 3m / min to 17m / min.

Referring to FIGS. 8 (a) and 8 (b), it can be seen that leakage may occur even if the break test is passed. This means that although the welded portion 61 may have sufficient strength, leakage may occur in a specific portion due to instability of the welded portion.

According to the experiment described above, the beam size is preferably 200 to 375 占 퐉, the laser moving speed is preferably 7 to 15 min, and the output is preferably 200 to 800 W. The most preferred welding control conditions are those in which the above three conditions are performed together. Through the above numerical values, it has been found that, in order to perform the correct thin plate welding, the welding is performed in the heat conduction mode and the laser control condition is performed.

Although the laser control conditions that are preferably exemplified may have a variety of factors, the cause presumed by the inventor will be described in more detail.

The output of the laser and the moving speed of the laser affect the energy per unit area of the portion irradiated with the laser, and the irradiated area of the laser affects the size of the welded portion as the beam size.

The relationship between the output of the laser and the moving speed of the laser will be further described, assuming that the energy per unit area is the same. First, if the moving speed of the laser is increased, the laser output must be increased to obtain the same energy per unit area. However, in this case, although the work speed can be improved by increasing the moving speed of the laser, there is a high possibility that the output of the laser is too high to operate in the keyhole mode, the thin plate is likely to oxidize, There is great concern. Therefore, there is a high possibility of welding failure and breakage. Conversely, if the moving speed of the laser is lowered, the laser output should be lowered to obtain the same energy per unit area. In this case, the opposite effect may occur, for example, there is a fear that the productivity is lowered due to the low moving speed, and the solidified portion may not be provided in a proper shape due to the long-term flow of the molten portion. When the beam size of the laser is increased, too much transmission energy is given, so there is a high possibility of operating in the keyhole mode and the width of the welded portion is widened so that the length l of the molten portion 611 becomes long, The width of the welded portion is increased, and there is a high possibility that the welded portion is defective. If the beam size of the laser is too small, the transfer energy is small and the thin plate and the base material are not sufficiently melted.

The inventors have found that when the thin plate or the base material is melted by the laser and then the flowable melt portion solidifies after showing any flow in the liquid state, okay. Here, what has the greatest influence on the performance of the welded portion is that leakage does not occur in the welded portion, and secondly it has a predetermined strength.

First, the properties of the melting portion 611 determined by the inventor will be described. The thin plate 112 has a part of the thickness of the base material 111 placed below the thin plate 112 and is melted. As a result, a slight amount of volume expansion occurs as the liquid melts. The expanded melt is solidified while showing the flow toward the back and both sides with respect to the traveling direction of the laser. At this time, the longer the width and the depth of the melted portion 611, the more slowly the wall is solidified, so that the molten portion 611 solidifies later and the flow rate of the molten liquid as a whole is large. As a result, the molten liquid flows locally, There is a risk that leakage may occur. In this case, it was confirmed that the shape of the bead was not regular. In addition, the strength and the strength of the solidified portion 612 may be large due to the wide width and the thickness of the solidified portion 612, and the length of the molten portion 611 may become long, which may cause leakage due to pneumatic pressure. In contrast, if the width and depth of the molten solder 611 are short, the molten solder 611 is solidified rapidly, and the amount of the molten solder 611 as a whole is small, so that the melt may not melt to such an extent that the molten solder 611 can fill the thin plate and the base material. As will be appreciated, the width and depth of the fused portion 611 can be increased as the energy per unit area of the laser is greater and the beam size of the laser is greater.

It can be confirmed that the shape of the solidified portion 612 formed by the molten portion 611 having a proper flow amount of the molten liquid under the above-described background is provided as follows.

Fig. 9 shows the shape of the solidified portion when the width and thickness of the fused portion are large, and Fig. 10 shows the shape of the solidified portion when the width and thickness of the fused portion are small. The shapes of the two solidified portions were observed to have no leak and the shape of the solidified portion judged to have appropriate tensile strength. For example, referring to FIG. 8, the solidification portion of FIG. 9 has a laser output of 960 W, a laser movement speed of 15 m / min and a laser beam size of 375 μm, and the solidification portion of FIG. The laser output is 240W, the laser traveling speed is 7m / min, and the laser beam size is 200μm.

9 and 10, the shape of the beads 620 320 shown in the solidification portion 612 is a shape of a bent region 621 631 provided in a parabolic shape at the center of the molten portion 612, And may include a linear region 622 632 provided in a shape corresponding to both sides of the bent region 621 631 and an edge region 623 633 provided at an end thereof. have. The bead refers to the unevenness appearing at the moment of solidification. The number of the beads increases as the width and length of the fused portion 611 become smaller.

As the width and length of the melted portion 611 are shorter, the widths of the bent regions 621 and 631 become larger, the lengths of the straight regions 622 and 632 become shorter, The angle &thetas; It is difficult to define the angle of the edge regions 623 and 633 by a no-sleep condition with the portion which is not melted and the widths of the bent regions 621 and 631 and the linear region The lengths of the beams 622 and 632 vary greatly in all the specimens due to the beam size of the laser, and it is difficult to grasp the characteristics thereof.

The inventor has confirmed that the angle formed by the linear regions 622 and 632 and the number of beads included in the unit length of the solidified portion can be defined.

In FIG. 9, the angle formed by the linear regions 622 and 632 with the welding direction is 9.462 degrees, and the number of beads is 20 per 1 mm. In FIG. 10, the angle formed by the linear regions 623 and 633 with the welding direction is 42.184 degrees, and the number of the screws is 100 per 1 mm. The shape of the solidified portion capable of performing stable welding without leakage in the welded portion 61 can be defined as the angle formed by the linear region with the welding direction and the number of beads. As a concrete numerical value, the angle of the linear region may be defined as 9 degrees to 43 degrees, and the number of the beads may be 20 to 100. It is preferable that the shape of the solidification portion of the proposed welded portion is all provided within the above-mentioned numerical value range.

The lower limit of the angle of the linear region and the number of beads is that the amount of flow of the melt is large so that the molten portion is provided with a portion that does not connect the base material to the thin plate , It may mean that a leak occurs locally while welding a welded part of several tens of meters in length. The lower limit of the angle of the linear region and the number of beads is that the melt is not melted to such an extent that the molten liquid can fill the thin plate and the base material because the flow amount of the melt is small and the melt does not fill the thin plate and the base metal while welding the tensile- Or a portion where the base material is not locally melted may occur, which may lead to leakage as a whole.

11 is a graph showing the shape of a solidified portion as a result of an experiment while changing the laser output and the laser moving speed at a laser beam size of 200 mu m. Referring to FIG. 11, it can be seen that the beads are regularly provided and that the solidified portion having the beads of the above-described pattern has no leakage.

Referring to FIG. 11, it can be assumed that the beads of the solidified portion are not regularly provided because the flow of the molten portion is too large or too small to ensure proper fluidity. However, it has been confirmed that leakage occurs locally at a predetermined length while the solidified portion is regularly provided. For example, when a laser output of 240 W is applied at 10 m / min. At this time, no leakage occurred when the experiment was performed with a short specimen, but when the specimen was tested with a relatively long specimen, the leakage occurred locally. In this case, it can be confirmed that the thickness of the solidified portion affects the stability of the welded portion 61 when the base material is not locally fused. It can be seen that the minimum thickness of the hardened portion, which the base material must melt, must be considered for this purpose.

12 is a graph showing energy per unit area and depth of a welded portion. In FIG. 12, the horizontal axis represents the energy intensity per unit area (W / m ² T) and the vertical axis represents the weld depth of the welded portion as compared with the thickness of the thin plate as a dimensionless number.

Referring to FIG. 12, as described above, the energy per unit area can be obtained through the above two values as a value proportional to the laser output and the movement of the laser. If the energy per unit area of the laser increases, it is not preferable because welding failure may occur due to approach to the keyhole mode in welding. Therefore, it is preferable that the energy applied to the welding does not reach the keyhole mode.

Fig. 13 shows the results of testing the depth and tensile strength of welds.

Referring to FIG. 13, in various experiments, when the depth of the welded portion exceeds 200 탆, the tensile strength suddenly decreases.

Referring to FIGS. 12 and 13, when the thin plate is assumed to be 50 탆, the depth of the welded portion exceeds 200 탆 and the tensile strength of the welded portion sharply drops. Therefore, it is preferable that the depth of the base material to be melted does not exceed three times the thickness of the thin plate, and it is preferable that at least 0.1 times of the thin plate is melted. It can be confirmed that the minimum melting depth of the base material prevents locally non-melting portions from occurring. It has been confirmed that satisfying the above numerical values can be achieved as the laser control condition proposed above.

The above embodiment can be preferably applied to the door side vacuum insulator of the refrigerator. However, even in a main body of a refrigerator or a duct penetrating a vacuum insulator, resistance against the force due to the vacuum pressure and the force due to the frictional force are the same, so that the same contents can be applied.

According to the present invention, it is possible to stably and uniformly provide a weld part which is essentially required for manufacturing a refrigerator to which a vacuum insulator is applied. Therefore, the effect of approaching the technology of providing a refrigerator using a vacuum insulator can be obtained.

61:
611:
612:

Claims (12)

A body provided with an internal space capable of storing the storage; And
And a door provided to be able to open and close the interior space from an external space,
Wherein at least one of the body and the door includes a vacuum insulator,
In the vacuum heat insulating member,
A first plate member defining at least a portion of the wall for the interior space;
A second plate member defining at least a portion of a wall for said outer space; And
A vacuum space part which is a space between the temperature of the inner space and the temperature of the outer space and is a vacuum space and includes a conductive resistance sheet capable of resisting thermal conduction between the first plate member and the second plate member And,
At least one of the conductive resistance sheet and the plate member is welded to each other to provide a weld,
A plurality of regular beads are provided on the surface of the welded portion,
In the bead,
A parabolic curve region provided at a central portion;
A linear region provided on both sides of the bent region; And
And an edge region provided outside the linear region. The method according to claim 1,
Wherein an angle formed by the linear region with the welding direction is 9 to 43 degrees. The method according to claim 1,
Wherein the number of the beads is 20 to 100 pieces / 1 mm based on the welding direction. The method according to claim 1,
Wherein a thickness of the plate member melted to be provided in the welded portion is 0.1 to 3 times the thickness of the thin plate. The method according to claim 1,
Wherein the welding is performed by laser welding. 6. The method of claim 5,
The laser welding control conditions include,
The beam size is 200 to 375 占 퐉, the laser moving speed is 7 to 15 m / min, and the output is 200 to 800 W. The method according to claim 1,
Wherein the beads are regularly provided. A body provided with an internal space capable of storing the storage; And
And a door provided to be able to open and close the interior space from an external space,
Wherein at least one of the body and the door includes a vacuum insulator,
In the vacuum heat insulating member,
A first plate member defining at least a portion of the wall for the interior space;
A second plate member defining at least a portion of a wall for said outer space; And
A vacuum space part which is a space between the temperature of the inner space and the temperature of the outer space and is a vacuum space and includes a conductive resistance sheet capable of resisting thermal conduction between the first plate member and the second plate member And,
At least one of the conductive resistance sheet and the plate member is welded to each other to provide a weld,
The weld is performed by laser welding in a thermal conduction mode,
Wherein a thickness of the plate member melted in the welded portion is 0.1 to 3 times the thickness of the conductive resistance sheet. 9. The method of claim 8,
In order to provide the weld, the laser moving speed is 7 to 15 m / min and the output is 200 to 800 W. 9. The method of claim 8,
Wherein at least a linear region is included in a bead provided on a surface of the welded portion. 9. The method of claim 8,
Wherein the conductive resistance sheet is 10 to 200 micrometers, and the plate member is 500 to 2000 micrometers. 12. The method of claim 11,
Wherein the plate member is provided at a thickness of 10 to 100 times the thickness of the conductive resistance sheet.

Images