JP5258636B2 - Thin brazing sheet fin material for high temperature brazing and manufacturing method of heat exchanger using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brazing sheet fin material used for an aluminum alloy heat exchanger and a method for producing a heat exchanger using the same, and more specifically, corrugated fin material exceeding 610 ° C. The present invention relates to a fin material suitable for brazing at a high temperature reaching temperature of 622 ° C. or lower, and a method for producing a heat exchanger using the same.

  Aluminum alloy heat exchangers are suitable for mass production, because the aluminum alloy material is lightweight and has good thermal conductivity, and brazing using a brazing aluminum brazing sheet pre-clad with brazing material For this reason, it has been widely used in the past, and in particular, is widely used in automobile radiators, air conditioner evaporators, capacitors and the like.

In recent years, heat exchangers for automobiles tend to be further reduced in weight, and therefore, there is a strong demand for reducing the thickness of each constituent material such as a brazing sheet fin material . The brazing sheet fin material is mainly used when joining to a member having no brazing material on its surface, such as an extruded multi-hole tube material . Generally, the core material is made of an Al-Mn alloy, and is formed on both surfaces of the core material. A three-layer clad material in which a brazing material made of an Al-Si alloy is joined is used.

Conventionally, as this kind of brazing sheet fin material , the one having a plate thickness of 100 μm or more has been mainstream, but recently fin materials thinner than this have been used. Here, the following: thickness 85μm called thin fin material, in such a thin fin material, for various properties such as resistance to wax core erosion and high-temperature deformation due during brazing, conventional Compared to thick fin materials (for example, those having a plate thickness of 100 μm or more), there are disadvantages.

In addition to reducing the thickness of the material, improving the production efficiency of the heat exchanger is also an important issue, but if the brazing process can be completed by heating in a short time, the efficiency of mass production can be increased directly. . Furthermore, if attachment parts that have been attached in a separate process after the conventional brazing can be joined at the same time when the fin material and the tube material are brazed, the production efficiency can be further improved.

One specific measure for improving the productivity efficiency is to shorten the brazing heating time by setting the temperature in the brazing furnace higher than the material temperature, that is, by setting a so-called temperature head. Can be considered. According to such a method, it is possible to raise the temperature in a relatively short time even for members such as a header tank having a large heat capacity among the constituent members of the heat exchanger, and for attachment members such as a fixture having a large heat capacity. At the same time, brazing and joining are possible.

Even in the case of brazing heating with a temperature head attached as described above, the heating rate of the member having the largest heat capacity among the heat exchanger components to be brazed becomes the slowest. It is necessary to raise the temperature to a temperature (for example, 600 ° C.) sufficient to braze the joint sufficiently. On the other hand, the fin member is a thin member having the smallest heat capacity among the heat exchanger components, and reaches a higher temperature (for example, a temperature exceeding 610 ° C.) than the other members. Therefore, when applying such a brazing heating method with a temperature head, a fin material that can be brazed normally at a higher temperature than usual is necessary, but the technology for realizing this with a thin brazing sheet has been established so far. The fact is that it was not done.

By the way, as a technique regarding a thin brazing sheet fin material, the thing as shown to patent document 1 and patent document 2 has already been proposed, but all brazing sheet fin materials by these proposal techniques are 610 degreeC. It is thought that it cannot withstand the high temperature brazing conditions exceeding.

That is, the technique disclosed in Patent Document 1 relates to a brazing sheet fin material having a plate thickness of 40 μm or more and less than 100 μm, and a combination of an Al—Mn alloy core material having a specific composition and an Al—Si brazing material. By controlling the Si content and brazing clad rate of the core and core material, unbonding due to the lack of molten brazing flowing into the joint during brazing is prevented, and other high temperature buckling resistance (sag resistance) is achieved. The main point is to be good. The claim of Patent Document 1 defines the joining condition when heated at 600 ° C. for 3 minutes, and the description in the text also mentions that the heat exchanger is usually brazed at about 600 ° C. Therefore, no problems have been recognized for brazing at higher temperatures, and of course no solution to the problem of brazing at higher temperatures above 610 ° C. I can't suggest.

Meanwhile, techniques disclosed in Patent Document 2 relates to the following brazing sheet fin material thickness 60 [mu] m, mainly by adjusting the average circle-phase equivalent diameter of Si particles in the brazing material 3μm or less, It is said that intergranular corrosion resistance, high temperature buckling resistance, and the like are improved. In the case of this Patent Document 2, there is a description that the temperature is normally raised to about 600 ° C. for the brazing conditions, and the examples are the same. Therefore, the technique of this Patent Document 2 also uses a thin fin material. It is clear that no consideration is given to brazing at high temperatures above 610 ° C.

Japanese Patent No. 3170202 JP 2008-6480 A

In order to enable brazing by heating with a temperature head as described above, brazing is performed while maintaining a normal corrugated shape even if the maximum temperature reached during brazing of the material exceeds 610 ° C. A sheet fin is required, and it is strongly desired to realize this with a thin fin material of 85 μm or less. However, in order to realize this, it is necessary to overcome the technical problems that have not occurred in the conventional brazing temperature of about 600 ° C. or a thicker fin material .

  In other words, the inventors of the present invention, when brazed in a corrugated state of a thin fin material of 85 μm or less at a high temperature exceeding 610 ° C., collapsed the end of the corrugated fin, which is different from the high temperature buckling of a normal fin. We found that a unique problem of deformation occurred.

This problem will be described in detail with reference to FIGS. 1 and 2. FIGS. 1 and 2 illustrate a brazing sheet fin material 1 that has been pre-corrugated to produce a heat exchanger core. This shows the situation in which the tube material 2 such as the hole extruded tube material and the header tank 3 are combined and heated to a high temperature brazing temperature exceeding 610 ° C., and their heat exchanger core elements are joined by high temperature brazing. In this case, the end portion 1A (for example, the end portion on the header tank 3 side) of the corrugated brazing sheet fin material 1 often exists as a free end that rises (or falls). In this case, if the thickness of the brazing sheet fin material 1 is as thin as 85 μm or less, the end portion 1A of the free end of the brazing sheet fin 1 as described above is formed at the time of heating at a high temperature exceeding 610 ° C. for brazing. 1 and FIG. 2 may be deformed as indicated by an arrow P and fall down to the tube side. In this way, if the fin end 1A is deformed to fall down, not only the appearance of the product is deteriorated due to the difference from the design shape, but also in the worst case, the deformed fin end 1A becomes a header tank (normally May come into contact with the brazing sheet), and the fins may be melted by the melting solder on the header tank side.

Such a unique deformation of the fin end is such that the fin material thickness is 85 μm by high-temperature brazing exceeding 610 ° C. even when the corrugated fin crest is not deformed or the buckling of the fin does not occur. The present inventors have the possibility that it may occur even in a brazing sheet fin material having a high resistance to high temperature buckling by conventional brazing heating at about 600 ° C. It has been confirmed by the experiment.

  Here, it is conceivable that the above-described specific falling deformation of the fin end portion 1A is influenced by the gravity applied to the end portion 1A which is a free end. However, when the present inventors have further studied, It has been found that even if each element of the core is set in such a direction that gravity is not applied in the direction in which the tip side of the portion 1A falls, that is, it is not simply caused by gravity. Therefore, it has been confirmed that this is a problem that cannot be solved simply by changing the direction of assembly during core assembly and brazing.

The present invention has been made against the background described above. When a brazing sheet fin material having a thickness of 85 μm or less is corrugated to assemble a heat exchanger core, for example, brazing and heating at a high temperature exceeding 610 ° C. An object of the present invention is to provide a brazing sheet fin material capable of reliably and effectively preventing the occurrence of the collapse of the fin end as described above.

In order to solve the above-mentioned problems, the heat exchanger core is assembled using corrugated thin-walled brazing sheet fin material , and collapsed at the fin end when brazing at a high temperature exceeding 610 ° C. As a result of various investigations and examinations, it was found that the surface tension due to excessive melting of the fin surface during brazing heating has an effect. That is, even if the corrugated fin material is cut at the peak of the peak portion by design, when it is assembled with the tube material etc., it floats at a certain frequency (not in contact with the tube material) state), in which case, the surface tension of the molten brazing fillet around crest adjacent during brazing heating (part of FIG. 2 F), found to be pulled into the tube side as indicated by an arrow Q in FIG. 2 did. In particular, in high-temperature brazing exceeding 610 ° C., the amount of melting brazing increases rapidly compared with the conventional brazing heating at about 600 ° C., so that the melting brazing from the adjacent fillet F side is performed. The tensile force Q due to the surface tension of the thin fin is increased, and in the thin fin of about 85 μm or less, the fin end portion 1A falls to the tube side as indicated by the arrow P, due to the fact that the material strength also decreases at a high temperature. It turned out that.

Here, when the conventional brazing at about 600 ° C. or a relatively thick fin material of about 100 μm or more is used, such a phenomenon hardly occurs. It was not done.

As described above, the inventors of the present invention, as described above, caused the collapse of the fin end due to excessive surface tension of the molten brazing, so that the molten brazing does not become excessive even at high temperature brazing exceeding 610 ° C. If properly controlled, it should be possible to prevent the end of the fin from falling down, and based on this, the amount of Si in the brazing material of the brazing sheet fin material and the brazing material cladding rate were reviewed. The inventors have found that the above-described problems can be solved by appropriately adjusting these in relation to each other, and have reached the present invention.

Specifically, the thin brazing sheet fin material for high temperature brazing according to the first aspect of the present invention is made of a clad material having a plate thickness of 40 to 85 μm in which a brazing material is bonded to both sides of a core material, and is subjected to corrugation to reach the material. It is a thin brazing sheet fin material that is brazed within a temperature range of 610 ° C. and 622 ° C. , and the core material is Mn 0.7 to 1.5 mass%, Si 0.3 to 0.8 mass%, Fe 0.05 Al—Si containing ˜0.75 mass%, the balance being made of an Al—Mn alloy composed of Al and inevitable impurity elements, and the brazing filler metal containing Si in the range of 5.5 to 8.0 mass%. The brazing material has a single-sided average cladding ratio in the range of 6.0 to 9.8%, the brazing filler metal Si content Sif (mass%) and the brazing material single-sided average clad. The value of Q determined by de ratio CR (%) formula by (1) is characterized in that it is 67 or less.
Q = Sif (mass%) × CR (%) ≦ 67 (1)

Further, the invention of claim 2 is the thin brazing sheet fin material for high temperature brazing according to claim 1, wherein the core material is Cu 0.05 to 0.25 mass%, Zn 0.3 to 3 in addition to the above elements. It is made of an Al-Mn alloy containing one or both of 0.0 mass%.

Further, the invention of claim 3 is the thin brazing sheet fin material for high temperature brazing according to claim 1, wherein the core material is Ti0.05 to 0.25 mass%, Zr0.05 to 0 in addition to the above elements. It consists of an Al-Mn alloy containing one or more selected from .25 mass%, Cr 0.05 to 0.25 mass%, V0.05 to 0.25 mass%. is there.

Further, the invention of claim 4 is the thin brazing sheet fin material for high temperature brazing according to claim 1, wherein the core material is Cu 0.05 to 0.25 mass%, Zn 0.3 to 3 in addition to the above elements. 0.0 mass% or both of Ti 0.05 to 0.25 mass%, Zr 0.05 to 0.25 mass%, Cr 0.05 to 0.25 mass%, V0.05 to 0.25 mass% It consists of the Al-Mn type alloy containing the 1 type (s) or 2 or more types selected.

Further, the invention of claim 5 is the thin-walled brazing sheet fin material for high temperature brazing according to any one of claims 1 to 4 , wherein the particle size in the thickness direction is in the brazing material layer. There Si particles exceeds 80% of the single-sided average brazing material thickness in a cross section parallel to the length direction of the brazing material parallel and fin material in the thickness direction of 0.2 or the longitudinal profile of the fin material / It does not exist beyond mm.

On the other hand, the inventions of claims 6 and 7 produce a heat exchanger using the thin brazing sheet fin material for high temperature brazing described in any one of claims 1 to 4 and claim 5, respectively. The inventions of claims 6 and 7 corrugate the fin material according to any one of claims 1 to 4 and claim 5, and Assembling the heat exchanger core with corrugated brazing sheet fin material as at least a part of the components, and in a non-oxidizing atmosphere so that the maximum temperature of the fin is in the range of over 610 ° C and below 622 ° C It is characterized by performing in-furnace flux brazing.

According to the brazing sheet fin material of the present invention, although the plate thickness is as thin as 85 μm or less, it is corrugated and assembled as a heat exchanger core and brazed at a high temperature exceeding 610 ° C. However, it is possible to reliably and effectively prevent the fin from deforming at the end of the fin, so that the commercial value as the heat exchanger core is impaired by the above-described collapse of the fin end. It can be effectively prevented, and there is no possibility that the tip of the fin comes into contact with the header tank due to the fall of the fin end and the fin is melted by the melting of the header tank.

Therefore, if the fin material of the present invention is used, brazing at a high temperature exceeding 610 ° C. using the thin fin material of 85 μm or less as described above is practically possible without causing any particular problems. As a result, it contributed to reducing the thickness of the fin material and contributing to the weight reduction of automobiles, and at the same time, it became possible to increase the production efficiency of heat exchanger products reliably and effectively by increasing the brazing temperature.

FIG. 1 shows a state where a heat exchanger core is configured by combining a corrugated brazing sheet fin material , a tube material , and a header tank in order to explain the phenomenon of the fin end collapse that is a problem to be solved by the present invention. FIG. FIG. 2 is an enlarged schematic view showing the main part of FIG. 1, particularly the situation near the fin end. FIG. 3 is a chart showing the relationship between the amount of Si in the brazing filler metal and the cladding ratio of the brazing filler metal and the occurrence of the fin end collapse phenomenon in the embodiment of the present invention.

In this invention, in order to contribute to the weight reduction of a heat exchanger, the brazing sheet fin material of 40-85 micrometers in thickness is made into object. If the plate thickness is smaller than this, it becomes difficult to produce a healthy brazing sheet, while if the plate thickness is larger than this, it is advantageous to prevent deformation during brazing of the fin. Such elaborate measures are not required, but it cannot be said that it contributes to the thinning and thus the weight reduction of the heat exchanger.

The thin brazed sheet fin material of the present invention is characterized by high resistance to deformation of the end portion of the corrugated fin by high-temperature brazing such that the maximum reached temperature exceeds 610 ° C. and falls within the range of 622 ° C. or less. It is important to define the material configuration for realizing the above. However, other characteristics desired as a heat exchanger fin material, such as normal buckling resistance, fin strength after brazing, sacrificial anodicity, and corrosion resistance of the fin itself, are naturally necessary. It is.

In the brazing sheet fin material of the present invention, the high-temperature brazing is achieved by adjusting the Si amount of the brazing material and the single-sided average clad rate of the brazing material to within a specific range and at the same time satisfying a specific relational expression. It is directly controlled so that the amount of molten solder at the time does not become excessive. By applying such a method, it is possible to reliably limit the amount of melting wax and prevent the fin end from falling down.

  Further, the present invention will be described in detail.

The brazing sheet to be used in the present invention has a thickness of 40 to 85 μm as described above, and the clad structure is brazed on both sides of the core material so as to be applied to the heat exchanger core by corrugating. The layers shall be joined. Here, as the core material , an Al—Mn alloy that is considered to be most suitable as a core material of a normal brazing sheet fin material is used, and as the brazing material, an Al—Si alloy is used.

  Therefore, first, the reasons for limiting the components of the core material, Al-Mn alloy, will be described.

Mn:
Mn is an alloy element that contributes to strength and deformation resistance at high temperatures, and is in the range of 0.7 to 1.5 mass%. If the Mn content of the core material is less than 0.7 mass%, the strength after brazing heating and the resistance to high temperature deformation become insufficient, which is not preferable. Further, if Mn is added to the core material in excess of 1.5 mass%, a coarse crystallized compound is formed during casting, resulting in an inhomogeneous structure.

Si:
Si is an element that contributes to strength and indirectly affects the amount of molten solder, and is in the range of 0.3 to 0.8 mass%. If the Si amount of the core material is less than 0.3 mass%, Si diffusion from the brazing material to the core material becomes significant during brazing, and the amount of molten brazing is substantially reduced, resulting in incomplete bonding of the fins to the tube. In some cases, it is inappropriate. On the other hand, if the Si content of the core material exceeds 0.8 mass%, the high temperature durability of the core material itself is lowered and the buckling resistance performance of the entire fin is deteriorated, which is inappropriate.

Fe:
Fe is one of the inevitable impurities of normal aluminum alloy, strength and because it contributes to the stabilization of the crystal structure, the I by the case may be slightly positively added, its amount of Fe Is in the range of 0.05 to 0.75 mass%. In order to make the amount of Fe less than 0.05 mass%, it is not suitable because it requires high-priced high-purity metal and not only leads to cost increase but also does not lead to property improvement. On the other hand, if Fe is added in excess of 0.75 mass%, a coarse crystallized compound is formed during casting, resulting in a heterogeneous structure.

  Further, as specified in claim 2, Cu and Zn may be selectively added to the core material alloy. However, if these are added excessively, the solidus temperature of the core material will be lowered, the strength at high temperature will be insufficient, and the fin deformation may occur overall when brazing the heat exchanger core, which is inappropriate. Become. In view of these, the amounts of Cu and Zn added were determined as follows.

Cu:
Cu is an alloy element that contributes to strength improvement, and is selectively added within a range of 0.05 to 0.25 mass%. If the amount of Cu is less than 0.05 mass%, the strength improvement effect after brazing heating cannot be sufficiently obtained. On the other hand, if Cu is added exceeding 0.25 mass%, in addition to the problem of fin deformation, the intergranular corrosion resistance of the brazed sheet fin after brazing is lowered, which is inappropriate.

Zn:
Zn is selectively added within the range of 0.3 to 3.0 mass%. This is for the purpose of improving the corrosion resistance of the tube by giving the brazing sheet fin material a property as a sacrificial anode. If the Zn content is less than 0.3 mass%, sufficient sacrificial anodic action cannot be obtained. On the other hand, if Zn is added in excess of 3.0 mass%, in addition to the problem of fin deformation, the self-corrosion resistance of the fin decreases. It becomes inappropriate.

  Furthermore, as the Al—Mn alloy of the core material, as defined in claim 3, Ti 0.05 to 0.25 mass%, Zr 0.05 to 0.25 mass%, Cr 0.05 to 0.25 mass%, V 0 One or two or more of 0.05 to 0.25 mass% may be contained.

  These Ti, Zr, Cr, and V are all elements that are selectively added to improve the strength and high temperature buckling resistance, and contribute particularly to the improvement of strength after brazing. When fins having high strength after brazing are required, it is effective to add these. In any case, if the addition is less than 0.05 mass%, no particular effect is obtained. On the other hand, if any addition exceeds 0.25 mass%, a coarse crystallized product is formed during casting, which is inappropriate.

In normal aluminum alloy casting, a refiner containing Ti for refinement of the cast structure, specifically an Al-Ti, Al-Ti-B or Al-Ti-C based master alloy. Often, a micronizing agent consisting of Ti contained in these is a compound particle such as Al ₃ Ti, TiB, TiC, etc., which is involved in solidification nucleation and has an effect on ingot crystal refinement. These particles do not have a direct effect on strength improvement. . Therefore, apart from Ti as the above-mentioned selective element for the purpose of improving the strength, it is possible in this invention to add Ti 0.005 to less than 0.05 mass% as a component derived from the micronizing agent, in combination with this. B0.0005 to 0.01 mass% or C0.0003 to 0.01 mass% may be added.

Next, the component composition of the brazing material in the brazing sheet fin material of the present invention, particularly the Si content in the brazing material, the clad rate of the brazing material, and their relationship will be described.

As for the brazing material of the brazing sheet fin material, the higher the Si content in the brazing material, the more the amount of molten brazing during brazing. Therefore, in the present invention, the amount of Si in the brazing material needs to be in the range of 5.5 to 8.0 mass%. Here, when the brazing material contains more than 8.0 mass% and contains Si, excessive melting brazing occurs at the time of brazing at a high temperature, which causes deformation of the end portions of the fins. On the contrary, if the amount of Si in the brazing material is less than 5.5 mass%, the brazing is not sufficiently performed, and the bonding between the fin and the tube may be partially defective, which is inappropriate.

As a brazing material component element, Al and unavoidable impurities may be basically used in addition to Si. However, in the brazing sheet fin material of the present invention, coarse Si particles in the brazing material can be formed as much as possible, as will be described later. It is desirable that the amount be small, and therefore, it is preferable to perform an improvement process in which a small amount of Na or Sr is added in order to refine the Si particles during casting. The addition amount of Na and Sr for making the Si particles fine is preferably in the range of 0.002 to 0.05 mass%. If each is less than the lower limit, there is no effect of refining Si particles, and even if the upper limit is exceeded, the effect of refining Si particles is saturated only by increasing the cost.

The brazing material of the brazing sheet fin material of the present invention usually contains Fe as another inevitable element, but the amount of Fe in the brazing material is preferably 0.6 mass% or less. Furthermore, in a normal brazing material, Cu or Zn may be added to adjust the potential after brazing and improve the corrosion resistance of the entire heat exchanger. If the melting point of the material is lowered, there arises a problem of promoting the falling deformation of the fin. Therefore, it is desirable to suppress each to 0.2 mass% or less. Moreover, you may add 0.001 to 0.1 mass% or less of Bi as an element for improving the fluidity | liquidity of a molten brazing material. If the amount is less than the lower limit, there is no effect of increasing the fluidity of the wax, and even if the upper limit is exceeded, the effect of increasing the fluidity of the wax is saturated only by increasing the cost.

Further, for the brazing material of the brazing sheet fin material of the present invention, not only the Si content is regulated within the range of 5.5 to 8.0 mass% as described above, but also the Si content and the brazing material single side. It is also important to regulate the relationship with the average cladding rate.

  Here, the average clad rate per one side of the brazing material needs to be in the range of 6.0 to 9.8%. If the cladding ratio exceeds this range, the molten brazing will be excessive and the end of the fin will be easily deformed. On the other hand, if it is lower than this range, bonding failure will occur, which is inappropriate.

The amount of Si and the cladding ratio of the brazing material must be regulated so that the value Q obtained by multiplying them is 67 or less if the Si amount is Sif (mass%) and the cladding ratio (%) is CR. . That is, it is necessary to satisfy the following expression (1).
Q = Sif (mass%) × CR (%) ≦ 67 (1)

  This equation (1) is obtained by the inventors and other detailed and numerous experiments as shown in Example 1 described later. That is, when the value Q on the left side of the equation (1) exceeds 67, it has been found that the amount of the molten solder becomes excessive and the corrugated fin end portion is deformed.

Further, in the brazing sheet fin material of the present invention, as defined in claim 4, the particle size in the thickness direction of the Si particles existing in the brazing material has a single-sided average brazing material thickness. Si particles exceeding 80% of the above are parallel to the thickness direction of the brazing material and the length direction of the fin material (the direction in which peaks and valleys are alternately located in the corrugated state, that is, the direction normally along the rolling direction) It is desirable to regulate the distribution density in the length direction of the fin material so that it does not exceed 0.2 pieces / mm in the cross section parallel to ().

Here, in the brazing material, in the portion where coarse Si particles having a thickness exceeding 80% of the average brazing material thickness are present, the thickness of the brazing material is locally increased. Sometimes the melting wax increases locally, and conversely, the substantial thickness of the core material decreases. Si particles can be examined by observing the cross-section of the fin material , but if the fin material length is 100 mm or more and the above defined particles are present in the observation length exceeding 0.2 particles / mm, There are many parts where there is a lot of molten brazing, and the corrugated fin end tends to fall down during high-temperature brazing, and there is a possibility that significant erosion that penetrates the core material of the fin may occur.

  Specific means for satisfying the Si particle conditions as described above include lowering the amount of Si in the Al-Si alloy as a brazing material within a specified range, and increasing the cooling rate during casting, Furthermore, the improvement process by fine addition of Na and Sr as already described in order to reduce the size of Si particles during casting may be mentioned.

The specific method for producing the thin brazing sheet fin material of the present invention as described above is not particularly limited, and may be carried out in the same manner as in the production of a normal three-layer clad brazing sheet. A typical desirable example is described below.

First, an alloy ingot of a core material and a brazing material, which are constituent elements of a brazing sheet fin material , is produced by a semi-continuous casting method (DC casting method). Thereafter, the thickness is adjusted by chamfering or pre-hot rolling, and the brazing material is arranged on both sides of the core material so as to obtain a predetermined cladding ratio, and the temperature is maintained at 400 to 540 ° C. for 0.5 to 15 hours. Preheating for hot rolling is performed under the conditions, and clad joining is performed by subsequent hot rolling. Following hot rolling, cold rolling is performed at a rolling reduction of 85 to 98%, intermediate annealing is performed at a temperature of 320 to 500 ° C. for 0.5 to 10 hours, and cold rolling is performed at a rolling reduction of 10 to 60%. Therefore, an H1n material having a predetermined plate thickness may be used.

The brazing sheet fin material manufactured in this way is slit to a predetermined width, and then corrugated and cut, and a member constituting a heat exchanger core in combination with a tube material , a header tank, a side plate, etc. It becomes.

Furthermore, as a specific condition for producing a heat exchanger core using the brazing sheet fin material of the present invention, as defined in claim 6, corrugating the brazing sheet fin material as described above, In addition, the heat exchanger core is assembled by using the corrugated brazing sheet fin material as at least a part of the constituent elements, and the non-oxidizing atmosphere is set so that the maximum temperature of the fin is within the range of 610 ° C. to 622 ° C. In-furnace flux brazing is suitable.

  Then, the conditions of the manufacturing method of such a heat exchanger are demonstrated in detail next.

Corrugation processing of the brazing sheet fin material may be performed by a conventional general method and is not particularly limited. The corrugated brazing sheet fin material is appropriately cut to the required dimensions, assembled together with other heat exchanger core components such as tube material and header tank, and in-furnace flux brazing in a non-oxidizing atmosphere . As a flux brazing method in the furnace in a non-oxidizing atmosphere, specifically, a general brazing method known as a nocolok brazing method can be applied. In the case of the vacuum brazing method, since the brazing flow behavior is different from that of the nocolok brazing method, there is no guarantee that the problem can be solved by the conditions defined in the present invention, and therefore it is desirable not to apply the vacuum brazing.

In brazing heating, it is appropriate that the material arrival temperature of the fin material is in the range of more than 610 ° C. and 622 ° C. or less. If the ultimate temperature is 610 ° C. or lower, the advantage of high temperature brazing that shortens the brazing process sufficiently and enables simultaneous joining of high heat capacity members cannot be obtained. On the other hand, in extremely high temperature brazing where the ultimate temperature of the fin material exceeds 622 ° C., there is a possibility that the overall high temperature buckling of the fin material and the deformation of the end portion of the corrugated fin occur, which is not practical.

  Here, in the case of aiming at brazing in a short time, it is desirable that the time during which the fins exist in a temperature range of 470 ° C. or higher is within 12 minutes during heating and heating for brazing. More preferably within minutes. The cooling after reaching the maximum temperature during brazing is preferably performed at a rate of 50 ° C./min or more.

  Examples of the present invention are shown below together with comparative examples. The following examples are for showing the effects of the present invention, and it is needless to say that the examples do not limit the technical scope of the present invention.

Example 1:
This Example 1 corresponds to a preliminary examination result for obtaining conditions for the amount of Si in the brazing material and the brazing material single-sided average clad rate necessary for preventing deformation of the fin end.

In Example 1, an Al-Si based material using Al-1.1 mass% Mn-0.35 mass% Si-0.4 mass% Fe alloy as the core material, and various amounts of Si and clad ratio were changed on both sides of the core material. A brazing sheet fin material having a plate thickness of 70 μm, to which a brazing material made of an alloy was bonded, was produced. The amount of Fe in the brazing material was in the range of 0.2 to 0.25 mass%, and in order to suppress the formation of coarse Si particles, 0.003 mass% of Na was added during casting. Here, the core material and the brazing material were produced by ordinary DC casting, and the subsequent steps were also in accordance with the usual method of performing clad joining by hot rolling, cold rolling and intermediate annealing.

In order to investigate fin end deformation, brazing sheet fin material with a width of 16 mm was corrugated (height 7 mm, fin crest 2 mm each), and the length was adjusted to about 80 mm. High temperature heated in a nitrogen atmosphere furnace after being combined with an extruded multi-hole tube material consisting of the above, assembled into a 5-stage fin mini-core sample that imitates a heat exchanger, coated with fluoride-based flux and dried It used for the brazing test. During brazing, a mini-core sample was placed so that gravity would not work in the direction in which the fin end fell.

  In this test, the material arrival temperature at the time of brazing was 621 ° C., and the rate of temperature increase between 470 and 570 ° C. during the temperature increase process was about 90 ° C./min, the time from 470 ° C. to the temperature reached. Heated to about 6-7 min. The cooling after brazing heating was performed at an average cooling rate of about 120 ° C./min. After such a brazing process, the fin ends are visually observed, and no fin end deformation (pass) if all of the fin ends are not collapsed by 30 ° or more from the original position in all 10 fin ends. The others were rejected. The results are shown in FIG. 3 corresponding to the amount of Si in the brazing material (Sif) and the brazing material single-sided average cladding ratio (CR). In FIG. 3, “◯” indicates a pass (no fin end portion is generated), and “X” indicates a fail (fin material end portion is generated). In FIG. 3, the solid line corresponds to the above-described equation (1), and the broken line corresponds to the upper limit of the Si amount and the cladding ratio of the brazing material defined in the present invention.

  As can be seen from FIG. 3, when the cladding ratio and the Si amount are increased, the tendency of the fins to collapse was observed. However, these two factors do not affect the collapse by themselves, but both As a result, it was found that the problem of the fin end falling deformation occurred. When the cladding ratio (CR) is 9.8% or less and the brazing filler metal Si amount (Sif) is 8.0 mass% or less, the area below the solid line in FIG. 3, that is, the Q value determined by the equation (1) is It has been found that in the region of 67 or less, it is possible to reliably prevent the end of the fin from falling down.

  Therefore, in the present invention, in addition to the upper limits of the brazing filler metal Si amount and the brazing filler metal single-sided average cladding ratio, the above equation (1) is defined. Thus, at the same time as satisfying the upper limit of the amount of brazing material Si and the upper limit of the cladding ratio, and in the appropriate region of the present invention satisfying the formula (1), even at high temperature brazing where the material temperature reaches 621 ° C., the fin end portion Deformation can be reliably prevented.

Example 2:
In the second embodiment, more conditions are variously changed.

  First, the core material having the composition shown in Table 1 and the brazing material shown in Table 2 were each DC cast and subjected to homogenization treatment by a normal method. Here, in the casting of the brazing material, a Si particle refinement process in which Na and Sr were added under some conditions was performed. The brazing material was hot-rolled to a predetermined plate thickness, combined with both the front and back surfaces of the chamfered core material ingot, further hot-rolled and clad-bonded. Thereafter, cold rolling, intermediate annealing and final cold rolling were performed to obtain a clad material (brazing sheet fin material) having a predetermined plate thickness. Table 3 shows the material configuration of the brazing sheet fin material which is a clad material.

The brazing material single-sided cladding ratio (CR) of the brazing sheet fin material and the Si particle distribution in the brazing material were measured by optical microscope observation of a cross section in the thickness direction along the length direction of the fin material . As for the Si particles, particles having a thickness dimension larger than the specified value in the observation length of 100 mm were counted, and the existence density was evaluated as the number per 1 mm.

  Furthermore, about each brazing sheet fin material as mentioned above, fin edge part deformation | transformation and evaluation of bondability were implemented as follows.

That is, a brazing sheet fin material having a width of 16 mm was corrugated (height 7 mm, fin crest 2 mm each) and aligned to a length of 80 mm. This is combined with an extruded multi-hole tube material made of pure Al-based alloy sprayed with Zn on the surface, assembled into a mini-core sample with 5 stages of fins imitating a heat exchanger, and fluoride-based flux is applied to the surface. After drying, it was subjected to a high temperature brazing test in which it was heated in a nitrogen atmosphere furnace. At the time of brazing, a mini-core sample was arranged so that gravity would not work in the direction in which the fin end fell. This test was carried out by selecting two levels of temperatures (614 ° C. and 621 ° C.) within the target material temperature range during brazing that is the target of the present invention. In the temperature raising process of brazing heating, the temperature rising rate was about 90 ° C./min during the material temperature of 470 to 570 ° C., and the time from 470 ° C. to the final temperature was about 6 to 7 min. Such a temperature increase in a short time was made possible by setting the temperature in the furnace to be 10 to 15 ° C. higher than the target temperature of the material.

  For comparison, a test was also performed at an ultimate temperature of 602 ° C., which is close to conventional ordinary brazing. In this case, the condition was 11 min from 470 ° C. to the ultimate temperature. The cooling after brazing heating was performed at an average cooling rate of about 120 ° C./min in all cases.

  Of the total 10 fin end portions of the mini-core after cooling, those deformed by 30 ° or more from a predetermined position were counted, and the fin end collapse deformation was evaluated.

  Moreover, as a soundness evaluation of the joint part of a fin, the fin was mechanically peeled and the surface was observed, and it was confirmed whether sufficient fillet was formed in each joint part of a fin and a tube. And it was judged that the thing in which sufficient fillet was formed in all the joining parts was favorable.

Further, the tensile strength after brazing of the fin is obtained by performing a tensile test in the longitudinal direction after heating in the same manner as the above-mentioned mini-core sample under the condition that the final temperature is 614 ° C. with a fin material without corrugating. It was.

  These characteristic evaluation results are shown in Table 4.

  From the results of the characteristic evaluation shown in Table 4, in the embodiment of the present invention, the fin end deformation is not caused by the high temperature brazing at which the ultimate temperature exceeds 610 ° C. and becomes 622 ° C. or less, and the fin and the tube are joined. In addition, it was confirmed that the fin strength after high temperature brazing was also high.

In some of the fin materials according to the embodiment of the present invention, a fin joint failure sometimes occurred under normal brazing conditions at an ultimate temperature of 602 ° C. (G1). Assuming brazing, this is not a particular problem.

On the other hand, some of the comparative examples can be used without problems under normal brazing conditions at an ultimate temperature of 602 ° C., but problems such as deformation of fin ends occur at high temperatures exceeding the ultimate temperature of 610 ° C. This indicates that even if the clad fin material is adequately suitable for normal brazing temperature, it cannot be used for high-temperature brazing, and this point is solved for the first time by the technology of the present invention. Yes.

  Further, each of the comparative examples NG1 to NG16 will be described.

  In Comparative Example NG1, the amount of brazing filler metal Si is low, and the fin and tube are poorly bonded after brazing.

  NG2 has a high amount of brazing filler metal Si, the value of Q in equation (1) is larger than specified, and high-temperature brazing has caused fin end deformation.

  Since both NG3 and NG4 have a high amount of brazing filler metal Si, a large Q value, and a large amount of Si particles in the thickness direction in the brazing layer, fin end deformation occurred due to high temperature brazing.

  Even in NG5, since the brazing material is high Si and the number of large Si grains is larger than specified, the fin end deformation occurred by high temperature brazing.

  NG6 and NG7 are examples in which the cladding ratio is high, the Q value is large, and fin end deformation is caused by high-temperature brazing.

  NG8 is an example in which the clad rate of the brazing material is low and bonding failure occurs even at high temperature brazing.

  In NG9, the amount of Mn in the core material was low, and the strength after high temperature brazing was low.

  NG10 is an example in which the core material has a high Mn content, and coarse crystals were observed after casting, so that there was a problem in the uniformity of the structure and the clad material was not produced.

  NG11 is an example in which the amount of Si in the core material is low and bonding failure occurs due to the effect of diffusion of Si in the brazing material into the core material.

  NG12 is an example in which deformation of the corrugated crest portion of the fin occurs in almost the entire area of the corrugated fin by brazing at 614 ° C. with the core material being high Si.

  NG13 is an example in which the core material is high Cu and deformed in almost the entire area of the fin by brazing at 614 ° C., resulting in deformation of the corrugated peak portion of the fin.

NG14 to NG16 are examples in which the addition amount of Ti, Cr, Zr, and V in the core material is large, and coarse crystals were observed after casting.

Although not shown in the table, even with the same structure as NG4 and NG6, the fin material with only a plate thickness of 95 μm does not undergo fin end deformation due to high temperature brazing at an ultimate temperature of 614 ° C. It was also confirmed that the problem to be solved is a problem peculiar to the thinned fin material .

The preparation of a comparative material in which the amount of Fe added to the core material is less than 0.05 mass%, which is lower than that of the present invention, requires the use of a high-priced aluminum ingot of at least 99.9 mass% or 99.99 mass%, Since the effect of is not expected, it was not implemented.

1 Brazing sheet fin 1A Fin end 2 Tube 3 Header tank

Claims (7)

A thin brazed sheet fin made of a clad material having a thickness of 40 to 85 μm with a brazing material bonded to both sides of a core material, and subjected to corrugation and brazing within a material temperature exceeding 610 ° C. but not exceeding 622 ° C. Material,
The core material contains Mn 0.7 to 1.5 mass%, Si 0.3 to 0.8 mass%, Fe 0.05 to 0.75 mass%, and the balance is made of an Al-Mn alloy composed of Al and inevitable impurity elements, The brazing material is made of an Al-Si based alloy containing Si in the range of 5.5 to 8.0 mass%, and the one-sided average cladding ratio of the brazing material is in the range of 6.0 to 9.8%. The Q value determined by the following formula (1) by the Si content Sif (mass%) of the brazing filler metal and the single-sided average cladding ratio CR (%) of the brazing filler metal is 67 or less, Thin brazing sheet fin material for brazing.
Q = Sif (mass%) × CR (%) ≦ 67 (1) In the thin brazing sheet fin material for high temperature brazing according to claim 1,
The core material is made of an Al-Mn alloy containing one or both of Cu 0.05 to 0.25 mass% and Zn 0.3 to 3.0 mass% in addition to the elements described above. Thin brazing sheet fin material for high temperature brazing. In the thin brazing sheet fin material for high temperature brazing according to claim 1,
The core material is selected from Ti 0.05 to 0.25 mass%, Zr 0.05 to 0.25 mass%, Cr 0.05 to 0.25 mass%, and V0.05 to 0.25 mass% in addition to the elements described above. A thin brazing sheet fin material for high temperature brazing, comprising an Al-Mn alloy containing one or more of the above. In the thin brazing sheet fin material for high temperature brazing according to claim 1,
In addition to the above elements, the core material further includes one or both of Cu 0.05 to 0.25 mass%, Zn 0.3 to 3.0 mass%, and further Ti 0.05 to 0.25 mass%, Zr0.05 to It is made of an Al-Mn alloy containing one or more selected from 0.25 mass%, Cr 0.05 to 0.25 mass%, and V0.05 to 0.25 mass%. Thin brazing sheet fin material for high temperature brazing. In the thin brazing sheet fin material for high temperature brazing according to any one of claims 1 to 4,
In the brazing material layer, Si particles having a particle size in the thickness direction exceeding 80% of the average brazing material thickness on one side are in a cross section parallel to the thickness direction of the brazing material and parallel to the length direction of the fin material. A thin brazing sheet fin material for high temperature brazing, characterized in that the distribution in the length direction of the material does not exceed 0.2 pieces / mm.   A fin material according to any one of claims 1 to 4 is corrugated, and the corrugated brazing sheet fin material is used as at least a part of a component to assemble a heat exchanger core. A method for producing an aluminum alloy heat exchanger, characterized in that in-furnace flux brazing is performed in a non-oxidizing atmosphere so that the highest temperature of the fin is in the range of more than 610 ° C. and 622 ° C. or less .   A heat exchanger core is assembled by corrugating the fin material according to claim 5 and using the corrugated brazing sheet fin material as at least a part of the constituent elements, and the maximum ultimate temperature of the fin exceeds 610 ° C. 622 A method for producing a heat exchanger made of aluminum alloy, characterized in that in-furnace flux brazing is performed in a non-oxidizing atmosphere so as to be within a range of ° C or less.

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