JPH0679769B2 - Method for manufacturing hollow structure made of A1 - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a hollow structure made of aluminum (Al) or an alloy thereof, and particularly when producing such a hollow structure by vacuum brazing, The present invention relates to a technique capable of advantageously reducing the amount of Mg used while improving its brazing property.

(Background Art) As a fluxless brazing method for a material composed of Al or an alloy thereof, conventionally, a brazing material containing about 1.0 to 2.0% Mg in an Al-Si alloy is used and heated in vacuum, The vacuum brazing method is known and is widely applied to the production of hollow structures such as heat exchangers. Then, the mechanism is that Mg in the brazing filler metal evaporates during heating in vacuum to getter the oxidizing gas remaining in the furnace and at the same time destroys the oxide film on the brazing filler metal surface during evaporation. It is recognized that the desired brazing property can be obtained. Further, in such a method, the brazing material is often used as a brazing sheet clad on the surface of an Al core material such as JIS-A-3003 alloy, and a special treatment is performed as a pretreatment before brazing. It is characterized in that degreasing is not necessary and is sufficient.

However, the following problems are inherent in manufacturing a hollow structure by a vacuum brazing method using such a brazing sheet.

First, Mg that evaporates from the brazing material during heating, adheres to and deposits on the furnace wall, etc., adsorbs an oxidizing gas when the furnace is opened to the atmosphere, and is released into the furnace during heating, causing brazing. Therefore, it is necessary to periodically remove the Mg deposited from the furnace, because in the actual production furnace, small-scale removal work must be performed before each heating and medium-scale removal work. Once every few weeks, and a large-scale cleaning with dismantling of the furnace is carried out once or twice a year. This cleaning work is a heavy operational burden, and it is necessary to reduce it. Had to reduce the amount of Mg used.

In addition, in such a brazing method, in order to obtain stable brazing properties, the Mg content in the brazing material is required to be 1.5% as a standard, 1.0% or more at a minimum, In addition to brazing filler metal, this required Mg content is
By placing a lump or an alloy containing Mg in the furnace, the amount can be reduced to some extent, but the total amount of Mg evaporated in the furnace cannot be reduced.

For example, in the case of a product with a joint inside and outside the product (hollow structure) such as the tank part of a drone cup type heat exchanger or radiator, the evaporation rate of Mg is different between the inside and outside, so it is standard. When such a material for vacuum brazing is used, there is a problem that the brazing property is deteriorated especially inside.
And, in order to improve the internal brazing property, it is effective to reduce the amount of Mg, but it is difficult to improve the internal brazing property within the range of the amount of Mg required for external brazing property. It was.

On the other hand, for the purpose of improving the brazing property of the hollow structure, Japanese Patent Publication No. 58-54909 discloses that the amount of Mg in the brazing alloy on the inner side is
It is proposed that the content be 0.2 to 1.2%, and that JP-A-59-85364 does not contain Mg in the brazing alloy on the inner side. At the joint that serves as the boundary between the inside and outside of the body, the brazing material on the inner side is exposed to the outer side to form a joint, leaving a problem in brazing property on the outer side. .

(Problem to be Solved) Here, the present invention has been made in view of such circumstances, and its problem is a method for producing an Al hollow structure by a vacuum brazing method using a brazing sheet. In order to improve the brazability of the hollow structure to obtain a stable joined state inside and outside the hollow structure, the amount of Mg used during brazing should be reduced, and the maintenance of the furnace cleaning should be greatly reduced. is there.

(Solution) The present invention, in order to solve the problem, obtained by molding a brazing sheet composed of a core material made of Al or an alloy thereof and a skin material made of an Al brazing alloy,
A cup-shaped molded body having a joint flange portion provided at the peripheral edge of the opening, the joint flange portion being folded back to the cup bottom portion side at the tip portion is used. The parts are stacked so that the cup bottoms face each other and are brought into contact with each other, and by joining by a vacuum brazing method, when manufacturing a hollow structure, as the brazing sheet, from Al or its alloy 6 on one side of the core material
First Al containing ~ 14 wt% Si and 0.8-2.5 wt% Mg
A first skin made of a brazing alloy is provided, while a second skin made of a second Al brazing alloy containing 6 to 14% by weight of Si and 0 to 0.6% by weight of Mg on the other side of the core material. A double-sided brazing sheet provided with a material is formed, and the second skin material of the double-sided brazing sheet is formed so as to be the inside of the cup shape to form the cup-shaped formed body and the cup-shaped formed body. 3 g / m ³ or more of Mg was present on the outer side of the stack formed by stacking, and the brazing operation was performed so that the cup-shaped compacts were bonded to each other.

Further, the present invention is, instead of the above method, obtained by molding a brazing sheet composed of a core material made of Al or an alloy thereof and a skin material made of Al brazing alloy, a joint flange at the opening peripheral edge portion. A cup-shaped molded body provided with a portion, and the joining flange portion is folded back to the cup bottom portion side at the tip portion, and such a cup-shaped molded body is joined to the joining flange portion and the cup bottom portion. Are stacked so that they are abutted against each other, and by joining by a vacuum brazing method, when manufacturing a hollow structure, as the brazing sheet, on both sides of the core material made of Al or its alloy. A first double-sided brazing sheet provided with a first skin material made of a first Al brazing alloy containing 6 to 14 wt% Si and 0.8 to 2.5 wt% Mg, respectively; Alternatively, a second double-sided brazing, in which a second skin material made of a second Al brazing alloy containing 6 to 14% by weight of Si and 0 to 0.6% by weight of Mg is provided on both sides of a core material made of the alloy, respectively. A sheet and a double-sided brazing sheet of each of the two types are used to form the cup-shaped molded body, and the cup-shaped molded bodies are combined and stacked in a form in which their joint flange portions and cup bottom portions are butted against each other, Two cup-shaped molded articles that constitute a stack and that are obtained by molding from the second double-sided brazing sheet are adjacent to each other in a form in which their joint flange portions are brought into contact with each other. together made present a set of, by allowed to exist a 3 g / m ³ or more Mg the outside of the laminate overlapped products, also the preparation of Al hollow structure and performing brazing operation, It is intended to be the subject matter, which also, it is is able to solve the problem described above.

In these methods of the present invention, the first Al brazing alloy and the second Al brazing alloy constituting the skin material of the brazing sheet may contain Bi at a ratio not exceeding 0.4% by weight, if necessary. As a result, the fluidity of the wax is increased and the fillet forming ability is increased.

(Specific configuration and action) By the way, in the vacuum brazing method using this brazing sheet to braze in a vacuum furnace, Mg is used to getter the oxidizing gas in the furnace without using flux. Since it modifies and destroys the oxide film on the surface of the material, about 1.0 to 2.0% of Mg is added to the brazing filler metal, or it is placed not only in the brazing filler metal but also in parts other than the brazing filler metal. However, as described above, in order to obtain the desired effect, the total amount of Mg released in the furnace must be increased, which was a problem in terms of furnace maintenance, etc. The problem is that the brazing property of the inner side of the hollow structure of a hollow structure such as an exchanger is poor especially at the joint between the inner and outer boundaries.

Incidentally, in the conventional case where the amount of Mg in the brazing alloy on the inner side of the hollow structure is large as much as the brazing alloy located on the outer side, the exhaust of evaporated Mg on the inner side is delayed,
As compared with the external side, which continues to evaporate vigorously, a larger amount of Mg remains in the brazing alloy, so the brazing alloy on the internal side melts and flows from an early stage due to the ternary eutectic of Al-Mg-Si. Most of them start to move to the outer side, so that the inner wax, which is important for forming the fillet on the inner side, is depleted early, and defects such as fillet breakage occur on the inner side.

In the present invention, in particular, in order to enhance the fillet forming ability on the inner side of the boundary portion where the joining flange portions of the cup-shaped molded body in the hollow structure are brought into contact with each other, the timing of melting and flowing of the inner wax is set to the The Al brazing alloy conventionally used as an effective means for that is because it was important to keep the brazing property on the external side inferior. When
It was designed to be used in combination with an Al brazing alloy with a reduced amount of Mg.The main purpose is to enable the formation of fillets both inside and outside, and to provide a time difference between the melting and flow of the brazing inside and outside. By not causing this, the bondability of the boundary of the hollow structure (joint flange) is dramatically stabilized, and the amount of Mg released into the furnace is reduced, greatly reducing the maintenance of the furnace. Is at the same time.

Therefore, in the hollow structure, the following points are respectively provided on the outer side and the inner side of the boundary portion (joint portion) where the joint flange portions are in contact with each other in order to obtain good brazing property. It is required.

That is, on the outer side, it is necessary to evaporate a considerable amount of Mg in order to getter a large amount of oxidizing gas present in the furnace. Because of the large amount of oxidization, the coating must be destroyed immediately before brazing, which requires a certain amount of Mg in the brazing alloy. However, if the brazing alloy contains a small amount of Mg, the degree of oxidation during heating is also small, so that there is no problem as long as the getter of the oxidizing gas is sufficiently performed.

On the other hand, on the inner side, since the amount of oxidizing gas present is small,
When there is no need for the getter of oxidizing gas and the destruction of the oxide film immediately before brazing to the extent of the external side, and when the degree of sealing is high, good fillet formation is possible even if Mg is not included in the braze alloy. It will be possible. However, in order to prevent the early depletion of the wax, it is necessary to make the timing of melting and starting the flow of the wax equal to that of the outside.

Therefore, in the present invention, as one of the measures,
On the outside of the cup shape of the cup-shaped molded body that gives the desired hollow structure, a skin material made of a predetermined Al brazing alloy with a large amount of Mg is placed, while inside the cup shape, Mg
The skin material made of a predetermined braze alloy with a small content was positioned. More specifically, as is clear from FIG. 1 showing a partial cross section of a Delon cup type evaporator, the first Al brazing material is formed on one surface (outer surface) of the core material 2 made of Al or an alloy thereof. While a first skin material 4 made of an alloy is provided, a second skin material 6 made of the second Al brazing alloy is formed on the other surface (inner surface) of the core material 2.
A double-sided brazing sheet provided with is used,
Then, this brazing sheet is formed into a predetermined cup shape so that the second skin material 6 is on the inside, and a joint flange portion 8 is formed at the peripheral edge of the opening, the tip end portion of which is folded back toward the cup bottom portion. A cup-shaped molded product 10 is obtained.
Then, the cup-shaped molded product 10 is
8 and 8 and the cup bottoms 9 and 9 are stacked so that they are brought into contact with each other so as to face each other to form a brazing combination body having a hollow structure.

Therefore, in such a combination, as is apparent from FIG. 1, the joint flange portion 8, which is provided at the peripheral edge portion of the opening,
In a set of cup-shaped molded products 10 and 10 formed by abutting each other, the second skin material 6 is brought into contact with each other to form a joint, and the cup bottoms are In the groups formed by facing each other, the first skin material 4 portions are brought into contact with each other to form a joint.

Further, in the present invention, as another measure, together with a cup-shaped molded article obtained by molding from a brazing sheet having a skin material made of a predetermined Al brazing alloy with a large amount of Mg on both sides, Mg, Stacked using a cup-shaped molded product obtained from a brazing sheet provided on both sides with a skin material made of a predetermined Al brazing alloy with a small content, and at that time,
A set of the latter cup-shaped molded products, which are assembled so as to face each other in a form in which their joint flange portions are brought into contact with each other, exists in a stack of such cup-shaped molded products. That is, for example, as shown in FIG. 2, a first skin material 4 made of the first Al brazing alloy is provided on both surfaces of a core material 2 made of Al or its alloy. And a second double-sided brazing sheet in which the second skin materials 6,6 made of the second Al brazing alloy are provided on both sides of the same core material 2 as described above. Two kinds of cup-shaped molded products 12 in which two kinds of double-sided brazing sheets are respectively formed into a predetermined cup shape, and joint flange portions 8 each having a tip end portion folded back toward the cup bottom portion are formed at the peripheral edge portion of the opening. , 14 and the cup-shaped molded products 12, 14 are stacked to form a brazing combination body having a hollow structure. Moreover, in such a combination, two cup-shaped molded articles 14 obtained by molding from the second double-sided brazing sheet are abutted as shown in FIG. A second Al brazing alloy joint having a low Mg content is thereby formed, and a cup obtained by molding the first double-sided brazing sheet to the pair of the butted cup-shaped molded articles 14 is also obtained. The shaped articles 12 are assembled by abutting them at their cup bottoms.

Then, the stack of cup-shaped molded products 10 and 12, 14 as shown in FIGS. 1 and 2 is subjected to a predetermined vacuum brazing operation in that state to obtain a desired hollow structure ( Evaporator) will be manufactured,
At that time, the outer part (a) of the joint formed on the outer side of the product formed by the second Al brazing alloy (6) having a low Mg content is used.
Part) in order to supply Mg to the present invention,
The brazing is performed so that Mg of ³ g / m ³ or more is present outside the stack.

It should be noted that, as the Mg that is allowed to exist on the outside, the first
As is clear from the drawings and FIG. 2, the first brazing alloy (4) located outside the stack contains Mg, and of course, the second brazing alloy (6) also contains Mg contained in what is exposed to the outside in the joint flange portion 8 provided in the opening peripheral portion of the cup-shaped molded product 14, and further other portions exposed to the outside in such a combination, and supplemented in the furnace. As a material or the like, it means the total amount of Mg contained in an alloy or the like to be supplemented at the time of brazing the stack, and Mg powder or the like inserted in the furnace for compensation.

Therefore, in FIG. 1 and FIG. 2, the first Al brazing alloy (4) having a large Mg content on the outer side and the stack are formed at the outer side portions (a portion and c portion) of the joint portion on the outer side of the product. Other externally exposed parts of the product, as well as the nets placed in the furnace other than the stack.
By vigorous Mg evaporation from alloys containing Mg or Mg,
The oxidizing gas around the joint is gettered.
Such an action of Mg can be expected due to the presence of ³ g / m ³ or more of Mg outside the stack, as described above. Note that the upper limit of this Mg abundance will be appropriately determined depending on the size and form of the stack, the capacity in the furnace, etc., but the presence of an excessively large amount of Mg is similar to the conventional furnace wall, etc. Since it causes the problem of Mg deposition on the surface, it is generally stopped at about 200 g / m ³ . In the portion a, the Mg content of the second Al brazing alloy (6) is small, but fillet formation is possible as long as the above-mentioned getter by the externally existing Mg is sufficient, and the above-mentioned c
In the section, the oxide film is destroyed by active Mg evaporation from the first Al brazing alloy (4), and fillet formation becomes possible.

On the other hand, the inner part (b part) in the joint part inside the product, which is composed of the second Al brazing alloy (6) with a low Mg content.
Then, the oxidizing gas is sufficiently gettered by a part of the Mg vapor evaporated on the outer side flowing into the inner side, so that the fillet can be formed. Moreover, the outer part (a part) and the inner part (b part) of the joint boundary part of such a cup-shaped molded product are both formed of the second Al brazing alloy (6) having a low Mg content. As a result, there is no time difference between the melting of the wax and the start of flow of the wax inside and outside, so that a good fillet is formed on both the outside and inside.

According to the method of the present invention, the brazing alloy (6) having a low Mg content is used to evaporate from the brazing alloy.
Since the amount of Mg decreases, the amount of Mg released into the furnace will decrease as a whole, and a portion of the Mg evaporated from the brazing alloy (4) will be absorbed by the brazing alloy (6). Therefore, the amount of Mg released into the furnace will be further reduced. Further, this absorbing action is caused by the fact that the brazing alloy (6) is promoted because it contains Si, and its effect is remarkable especially on the inner side of the hollow structure, and the brazing alloy (6)
The lower the Mg content, the more effective it is.

In addition, two kinds of Al brazing alloys (4,
In 6), when the Si content is less than 6% by weight, the fluidity is poor and the practicality is poor, and when it exceeds 14% by weight, the moldability is poor and the brazing is not performed. At times, the base material is corroded due to dissolution, which is not preferable. Further, in the first Al brazing alloy (4), when the Mg content is less than 0.8% by weight, the effect of destroying the oxide film due to rapid Mg evaporation becomes poor, and the brazing property on the external side is poor. While the Mg content is
If it exceeds 2.5% by weight, the formability will be poor and M
g Excessive amount released. Furthermore, a second Al brazing alloy (6)
When the Mg content exceeds 0.6% by weight, the effect of shortening the time difference between the melting and flow initiation of the wax inside and outside the hollow structure becomes poor, and the fillet forming ability inside the boundary (joint) is poor. This is not preferable.

In addition, the first and second Al brazing alloys (4, 6) include
Advantageously, Bi will be included. The reason for adding Bi is to increase the fluidity of the wax and improve the fillet forming ability, but the addition amount of Bi is 0.4.
If the content exceeds 10% by weight, the formation of groups (grooves generated by preferential wax flow and melting therein) becomes excessive and the appearance is not preferable.
It will be less than or equal to wt%.

Further, in the first Al brazing alloy (4) and the second Al brazing alloy (6) in the present invention, in addition to Bi, other alloying elements that have been clarified in the past for improving performance are also included. Added,
It is possible to add Pb, Sn, Ni, Cu, Zn, Be, L in each brazing alloy to improve brazing properties.
At least one element such as i, Ge is added in a trace amount, and Zn is added in the braze alloy in an amount of 0.1 to 1 in order to improve corrosion resistance.
It is possible to add about 0% by weight.

As described above, according to the present invention, a vacuum brazing operation is performed on a stack of cup-shaped molded products 10; 12, 14 in the form shown in FIGS. 1 and 2 in the presence of a predetermined amount of Mg. As with conventional vacuum brazing, the pretreatment prior to such vacuum brazing operation, which is carried out, is not particularly limited. However, in the case where oil stains or the like are significant, it is desirable to perform a degreasing treatment before brazing, and an etching treatment is also performed if necessary.

The brazing heating in the combined form of the cup-shaped molded product according to the present invention is performed under the same conditions as in the prior art in a vacuum furnace or a furnace having a structure corresponding thereto. For example, the pressure from immediately before melting of the wax to the end of heating is 1 × 10 ⁻³ Torr or less in vacuum, or a method of heating while displacing with an inert gas as necessary is adopted. When the pressure during vacuum heating becomes high, the brazing property becomes inferior, and inert gas replacement is performed in parallel with vacuum evacuation, which has the effect of eliminating the residual oxidizing gas in the furnace, It also has the effect of preventing atmospheric leaks into the furnace. Further, the cooling after the brazing is melted and the joining is completed is not particularly limited, and the cooling is performed in the same manner as in the past.

Incidentally, the hollow structure manufactured according to the method of the present invention,
In addition to the drone cup type evaporator described above and shown in FIG. 3 in its entirety, various heat exchangers manufactured by combining cup-shaped molded products obtained by molding a brazing sheet, and other There are hollow structures for use. By applying the method of the present invention as described above, the Mg cleaning of the furnace can be reduced to about 2/3 of the conventional case.

(Examples) Hereinafter, examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is subject to any restrictions due to the description of such examples. Not to mention that.

In addition to the following embodiments, the present invention further includes various changes and modifications based on the knowledge of those skilled in the art, in addition to the above specific description, without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

First, the core material 2 is a JIS-A-3003 alloy, and 15% of various first and second Al brazing alloys shown in Table 1 below are provided on both surfaces thereof.
Various double-sided brazing sheets (thickness: 0.6 mm) were produced by clad each. Next, each brazing sheet was molded so that the second Al brazing alloy (6) was inside the cup shape, as shown in FIG. 1, to obtain a cup-shaped molded product 10. Then, the obtained cup-shaped molded product 10 is laminated so that the peripheral edge portion of the opening, the joint flange portions 8 and 8 formed by folding back the tip portion toward the cup bottom portion and the cup bottom portions face each other. , Stainless steel disk 18 with ventilation hole 16 in the center
Are placed one above the other and assembled to form a laminated assembly 20 as shown in FIG.

Then, the obtained laminated assembly 20 was placed in a fully degassed stainless container having an internal volume of 5000 ml (0.005 m ³ ), 600 ° C. for 30 minutes, pressure: 5 × 10 ⁻⁵ Torr. It was heated and brazed. Further, in order to adjust the amount of evaporated Mg in the furnace, a predetermined amount of brazing alloy containing 1.5% by weight of Mg as a supplement was placed in a stainless steel container when heating some of the samples.

Similarly, in the laminated structure as shown in FIG. 2, a hollow structure having a shape as shown in FIG. 4 was produced by a vacuum brazing method. That is, various first Al brazing alloys shown in Table 2 below are clad on the both sides of the core material 2 made of JIS-A-3003 alloy by 15% to form various first double-sided brazing sheets ( (Thickness: 0.6 mm), while making various second Al brazing alloys shown in Table 2 below by 15% on both sides of the same core material, various second double side brazing Sheet (thickness: 0.6
mm) was prepared. Next, each of the first and second double-sided brazing sheets is formed into a cup shape as shown in FIG. 2, and a joining flange portion formed by folding the tip end portion toward the cup bottom portion is formed at the opening peripheral edge portion. Cup-shaped molded products 12 and 14 were obtained.

Then, the obtained two types of cup-shaped molded products 12 and 14 are laminated so as to face each other as shown in FIG. 2, and further a stainless disk 18 having a vent hole 16 in the center is arranged vertically. By assembling, a laminated assembly 20 as shown in FIG. 4 was produced and further vacuum brazed in the same manner as above to obtain the desired hollow structure.

In each of the brazed products thus obtained, the outer side (parts a and c in FIG. 4) and the inner side (b)
Part) to evaluate the brazeability by checking for fillet breakage, and to check the amount of Mg released into the furnace, the product weight before and after brazing (replenishment material for those using replenishment material) Was measured, and the respective results are also shown in Tables 1 and 2 below.

First, as is clear from Table 1, in the brazed product obtained in the combination form of the cup-shaped molded product of the double-sided brazing sheet shown in FIG. 1, fillet breakage does not occur inside or outside the brazed product. , Stable brazing results were obtained. It was also confirmed that the weight loss of the brazed product was reduced by 20-60% and the amount of Mg released into the furnace was reduced compared with the conventional method.

On the other hand, Mg existing outside the combination 20 of the cup-shaped molded product 10
In Comparative Example (1) in which the total amount of is outside the range of the present invention, even if the components of the first and second Al brazing alloys are within the content range of the present invention, in both cases, fillet breakage occurs on the outer side. And the second Al braze alloy (6) in Comparative Example (2)
Any of those whose Mg content is outside the range of the present invention causes fillet breakage on the inner side, and when the Mg content of the first Al brazing alloy (4) is outside the range of the present invention, replenishment is performed. Even when Mg was replenished with the material, fillet breakage occurred on the outside. Furthermore, in Comparative Example (3) in which the Si or Bi content is out of the range of the present invention, fillet breakage due to lack of effective brazing amount,
Alternatively, remarkable groove formation was observed on the product surface. Further, as in the conventional case, in the comparative example (4) in which the brazing alloy having a large Mg content was used as the first and second Al brazing alloys (4, 6), fillet breakage occurred on the inner side in all cases. Admitted.

Further, as is apparent from Table 2, a brazed product obtained from a laminated assembly 20 in which cup-shaped molded products 12 and 14 obtained from two kinds of double-sided brazing sheets are combined as shown in FIG. In that case, a stable brazing result was obtained without the occurrence of fillet breaks inside and outside. It was also confirmed that the weight loss of the brazed product was reduced by 20-60% and the amount of Mg released into the furnace was reduced compared with the conventional method.

On the other hand, in Comparative Example (1) in which the total amount of Mg existing outside the laminated assembly 20 during brazing is outside the range of the present invention, even if the components of the braze alloy satisfy the range of the present invention,
In both cases, fillet breakage occurred on the outer side. In Comparative Example (2), when the Mg content of the second Al brazing alloy (6) is out of the range of the present invention, fillet breakage occurs on the inner side, and the first Al brazing alloy ( When the content of Mg in 4) was out of the range of the present invention, fillet breakage occurred on the outer side even if Mg was supplied by the supplementary material. Furthermore, Si or
In Comparative Example (3) in which the Bi content is outside the range of the present invention,
Occurrence of cracks during molding, fillet breakage due to lack of effective brazing amount, or remarkable groove formation on the product surface was observed. Further, in Comparative Example (4) by the conventional method, it was confirmed that fillet breakage occurred on the inner side in all cases.

(Effects of the Invention) As is apparent from the above description, according to the method of the present invention,
In vacuum brazing of a hollow structure using a brazing sheet, its brazing property is dramatically improved,
As a result, problems such as leakage after brazing and insufficient pressure resistance, which are problems with hollow structures such as heat exchangers, could be effectively improved. Since the total amount of Mg vaporized from the furnace is reduced, the amount of Mg adhering to the furnace is reduced, and the maintenance of the furnace cleaning is significantly reduced. In addition, since the amount of evaporated Mg is reduced, the amount of products that can be loaded in the furnace at one time can be increased, and the productivity can be improved.

Further, according to the present invention, the difference in the timing of melting and flowing of the wax inside and outside the product having a hollow structure is reduced, so that stable brazing properties can be obtained even by a more rapid temperature rise. By doing so, we were able to realize an improvement in productivity.

[Brief description of drawings]

FIG. 1 and FIG. 2 are cross-sectional explanatory views related to an example of an assembling mode of a cup-shaped molded product that gives a portion of a drone cup type evaporator, and are cross-sectional views corresponding to II cross section in FIG. 3, and FIG. [Fig. 3] is a perspective view showing the whole of such a Delon cup type evaporator. FIG. 4 is a partially cutaway front view showing an assembly that constitutes the Delon cup type evaporator manufactured in the example. 2: Core material, 4: First skin material 6: Second skin material, 8: Joint flange part 9: Cup bottom part 10, 12, 14: Cup-shaped molded product 18: Stainless steel disc

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoei Teshima 1-1, Showa-cho, Kariya city, Aichi Prefecture Nihon Denso Co., Ltd. (72) Inventor Toshinari Sasaki 1-1-chome, Showa-cho, Kariya city, Aichi prefecture Co., Ltd. (72) Inventor, Keizo Namba, 3-12-12, Chitose, Minato-ku, Nagoya, Aichi Prefecture, Sumitomo Light Metal Industry Co., Ltd. (72) Inventor, Yasunaga Ito, 3-chome, Minen-ku, Nagoya, Aichi Prefecture No. 12 Sumitomo Light Metal Industry Co., Ltd. Technical Research Laboratory (56) Reference JP-A-59-22638 (JP, A) JP-B-58-54909 (JP, B2) JP-B-56-22638 (JP, B2)

Claims (4)

[Claims] 1. A cup-shaped molded body obtained by molding a brazing sheet composed of a core material made of Al or an alloy thereof and a skin material made of Al brazing alloy and having a joint flange portion at the peripheral edge portion of the opening. Then, the joining flange portion is folded back toward the cup bottom portion at the tip portion, and such a cup-shaped molded body is brought into contact with the joining flange portions and the cup bottom portions facing each other. When a hollow structure is manufactured by stacking as described above and joining them by a vacuum brazing method, as a brazing sheet, 6 to 14% by weight of Si is provided on one side of a core material made of Al or its alloy. And 0.8 to 2.5
A second skin containing 6 to 14 wt% Si and 0 to 0.6 wt% Mg is provided on the other side of the core while providing a first skin material consisting of a first Al braze alloy containing Mg by weight%. Using a double-sided brazing sheet provided with a second skin material made of Al brazing alloy, and forming the second skin material of the double-sided brazing sheet to be the inner side of the cup shape, the cup-shaped molded body And a brazing operation by allowing ³ g / m ³ or more of Mg to exist on the outside of the stack formed by stacking the cup-shaped compacts, and performing a brazing operation. 2. A cup-shaped molded body obtained by molding a brazing sheet composed of a core material made of Al or its alloy and a skin material made of Al brazing alloy, and having a joint flange portion at the peripheral edge of the opening. Then, the joining flange portion is folded back toward the cup bottom portion at the tip portion, and such a cup-shaped molded body is brought into contact with the joining flange portions and the cup bottom portions facing each other. When a hollow structure is manufactured by stacking and stacking in a vacuum brazing method, as the brazing sheet, 6 to 14% by weight of Si and 0.8% on both sides of the core material made of Al or its alloy is used. A first double-sided brazing sheet each provided with a first skin material made of a first Al brazing alloy containing 2.5 to 2.5% by weight of Mg;
Or 6 to 14% by weight on both sides of the core material made of the alloy
And a second double-sided brazing sheet provided with a second skin material made of a second Al brazing alloy containing 0 to 0.6% by weight of Mg, respectively. While forming the cup-shaped molded body, the cup-shaped molded bodies are combined and stacked in a form in which their joint flange portions and cup bottom portions are butted against each other to form a stacked product, and in the stacked product, the first Two cup-shaped molded articles obtained by molding from the two double-sided brazing sheet are allowed to exist in a set in which the joining flange portions are brought into contact with each other, and there is a set of 3 g / outer side of the stack. The feature is that brazing operation is performed by making Mg of m ³ or more exist.
Manufacturing method of Al hollow structure. 3. The method according to claim 1, wherein the first Al brazing alloy contains Bi in an amount of 0.4% by weight or less. 4. The method according to claim 1, wherein the second Al brazing alloy contains 0.4 wt% or less of Bi.