JPH11291028A - Manufacture of metal covering with brazing filler metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a metal whose surface is covered with brazing filler metal powder which is constant in the distribution of the brazing filler metal powder and capable of stably realizing the brazeability. SOLUTION: In a manufacturing method of a metal covered with a brazing filler metal after a hardening binder resin solution is applied to the surface of a metallic material, brazing filler metal powder is sprayed thereon and then, the binder resin is hardened. Alternatively, after hardening binder resin solution is applied to the surface of the metallic material, the brazing filler metal powder is sprayed thereon and after the binder resin is further applied thereto, the binder resin may be hardened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a metal material such as a tube and a strip coated with a brazing material, and more particularly, to a method of manufacturing a tube and a strip having a surface uniformly coated with a brazing material powder. About.

[0002]

2. Description of the Related Art As an example of a heat exchanger made of aluminum alloy, a condenser is shown in FIG. As shown in the figure, a tube 1 is a multi-hole tube by extrusion, and a fin 2 is a brazing sheet fin clad with a brazing material, and is integrally manufactured by a brazing method. 3 indicates a header pipe. By the way, in recent years, in order to reduce the size and weight of heat exchangers, fins that have a limit in thinning from the point of diffusion of brazing are thinned to bare fins, and brazing powder is applied to the outside of the tube with a binder, and these are combined. (Japanese Patent Laid-Open Publication No. 7-75844). The primary problem with this method is the formation of a coating containing brazing powder. When applying to a small number of tubes in a laboratory, it can be manufactured by applying a mixed solution of brazing powder and a binder with a roll coater, dipping, brushing, etc. In this case, the following problem occurs. The brazing filler metal powder mixed in the binder precipitates, and the distribution of the brazing filler metal powder in the binder solution becomes non-uniform, resulting in unstable brazing properties. When the concentration of the binder resin solution is increased, sedimentation can be prevented, but the thickness of the resin applied to the surface of the aluminum material is increased, so that the brazing property is reduced and the binder itself is useless. If the viscosity of the binder resin solution is reduced by lowering the concentration of the binder resin solution, the brazing powder flows along with the resin on the surface of the tube after application and before curing, resulting in an uneven brazing material adhesion state. If the binder and the brazing filler metal powder are mixed for a long period of time, the powder will agglomerate and the brazing filler metal will not be uniformly distributed on the surface of the aluminum material, so that the brazing property will decrease. Furthermore, since it is difficult to disperse the aggregated powder again, storage for a long time cannot be performed, and the resin (powder) remaining in the tank is wasted. In addition, it is not satisfactory in terms of evaporating the solvent, increasing the required binder coating amount, and the like.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the above-mentioned drawbacks of the conventional brazing material-coated metal material and realize a stable brazing property in which the distribution of the coated brazing material powder is constant. It is another object of the present invention to provide a method for producing a metal material having a surface coated with a brazing material powder.

[0004]

SUMMARY OF THE INVENTION The present invention uses a specific resin as a result of intensive studies to achieve the above object, and adopts a specific method of applying the resin and the brazing powder in a stepwise manner. As a result, it has been found that the object can be satisfied, and a metal material such as a tube or a strip having a surface coated with a brazing material can be manufactured industrially stably, and based on this finding, the present invention has been accomplished. That is, the present invention provides (1) a method for producing a brazing material-coated metal material, which comprises applying a curable binder resin solution to the surface of a metal material, spraying a brazing material powder, and then curing the binder resin. 2)
After applying the curable binder resin solution on the surface of the metal material,
A method of manufacturing a brazing material-coated metal material, comprising: spraying a brazing material powder, further applying a binder resin, and then curing the binder resin; (3) flux powder simultaneously with, or before or after the spraying of the brazing material; (1) or (2), wherein the flux is previously mixed with the curable binder resin (1). (5) The method for producing a brazing material-coated metal material according to any one of the items (1) to (3), (5) the metal material and the brazing material are Al-based alloys. (6) The method for producing a brazing material coated metal material according to (3) or (4), wherein (6) the brazing material powder is Si powder, Coiled brazing material coated metal material There is provided a method of manufacturing a brazing material-coated metal material according to any one of (1) to (6), characterized in that the wound into.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The metal material used in the present invention is not particularly limited as long as it is a metal material to which brazing bonding can be applied, but is preferably an aluminum alloy material, a copper-based material, or the like. Among these, the aluminum alloy material has a lower melting point than other metals and has a strong oxide film on the surface, so it is difficult to apply a conventional brazing material coating method such as hot-dip plating. It is particularly recommended as the metal material used in the method. Examples of the form of the metal material include a tube, a strip, and a plate. Taking an aluminum alloy material as an example, as long as the aluminum alloy is an aluminum alloy that can be used for brazing, an aluminum alloy suitable for each application is appropriately selected. For example, if it is a tube, alloy 3003,
1100 alloy, Al-Cu alloy, etc., as long as they are used as a fluid passage of a heat exchanger, 3003 alloy, 1100 alloy, Al-Mn-Cu alloy, etc. An article coated with an alloy or a pure aluminum-based alloy may be used. If the fin is used as a fin, an Al-Mn alloy, an Al-Fe alloy,
Pure aluminum alloys and alloys obtained by adding elements such as Zn to these alloys can be used. The above alloys are merely examples, and an aluminum alloy that satisfies the required characteristics depending on the part to be used may be used.

[0006] The aluminum alloy used for the tube or the strip is as described above. However, it is needless to say that the dimensions of the tube or the strip can be determined by the design of the equipment manufactured using the present material and are not particularly limited. Absent.
The brazing filler metal powder used in the present invention is an aluminum alloy brazing filler metal powder or a Si powder. Aluminum alloy powder is A
Typical alloys include l-Si alloys, Al-Zn alloys, and Al-Cu alloys, but are not limited thereto. That is, the composition may be any brazing material that can be brazed conventionally, but in consideration of corrosion resistance and brazing flowability, in particular, Al-Si alloys, Al-Si-Zn alloys, Al-Si- Cu-based alloy, Al-Si-Cu-Zn
Alloys and Al-Cu-Zn alloys can be particularly recommended.

It is preferable that 90% or more of these brazing materials have a particle diameter of 250 μm or less. In terms of dispersibility at the time of spraying, the particle size is more preferably 100 μm or less, and
0 μm or less is particularly preferred. When the tube and the strip are wound in a coil shape, particles having a particle size of 40 μm or less are preferable, and particles having a particle size of 30 μm or less are more preferable in order to make the coated brazing material powder particles difficult to peel off. On the other hand, if the brazing material powder is too small, the surface area of the brazing material powder increases, so that the amount of the oxide film on the surface increases, and the brazing property is reduced. However, it is more preferable that the thickness be 5 μm or more.

[0008] Since the shape of the brazing filler metal powder is desirably close to a sphere in terms of transportability during spraying (workability of spraying), the molten metal is atomized by a method such as an atomizing method or the like rather than a powder obtained by pulverizing the solidified brazing filler metal. Are preferably used.
In the present invention, Si powder can be used for the brazing material.
In this case, the Si powder has a particle diameter of 50 μm or less so as to react with the aluminum alloy of the tube or the strip to form a brazing filler metal, and a flux for breaking an oxide film on the surface of the aluminum alloy is used. However, since it is not necessary to consider the oxide film on the brazing filler metal surface, there is no problem even if the lower limit is about 0.5 μm. Since Si particles are often produced industrially by a pulverizing method, they are inferior to the above-mentioned aluminum alloy brazing materials in terms of transportability. These brazing filler metal powders may have their surfaces coated in advance with a flux used for brazing.

The curable binder resin used in the present invention is cured in a short time by the curing method described below, decomposed at a temperature lower than the brazing temperature, and a residue which adversely affects the brazing property and corrosion resistance is left at the time of decomposition. Not something. Examples include, but are not limited to, acrylic resins, methacrylic resins, urethane resins, epoxy resins, and the like. Curable resins that can be used as the binder include those described in JP-A-54-43853 and JP-A-1-14379.
No. 5, JP-A-6-39586 and the like. In the method of the present invention, a curable binder resin solution is applied to the surface of a metal material. The coating may be performed by dipping, a roll coater, spray coating, or the like, and a roll coater method is particularly preferable in terms of a coating speed.
The surface to be applied may be applied to both surfaces if the brazing material is required for both surfaces, to one surface if necessary for one surface, or to a required portion if necessary for a part. The resin may be used as a solution using a solvent such as water, alcohol, and toluene as needed.

The amount of the resin to be applied is preferably from 1 mg / m 2 to 3 g / m 2 after curing (in a state where the solvent is evaporated). If it is less than 1 mg / m 2, the powder of the brazing material sprayed in the next step is not sufficiently adhered and the coated brazing material is peeled off due to a slight change in the state thereafter. 3g / m2
When the temperature exceeds the above, the effect of attaching the brazing material does not change, so that the binder is wasted. In addition, since it takes time to cure the binder, the productivity of coating decreases. The brazing powder is sprayed on the metal material coated with the resin before the resin is cured. The powder is preferably sprayed with an inert gas such as nitrogen gas from the viewpoint of preventing exposure of brazing material powder such as aluminum alloy powder. The spraying method includes a method in which the powder is conveyed and sprayed with such a gas, an electrostatic coating method, and the like. The former method is preferable in terms of ease of handling and stability of the amount of the brazing material applied.

The brazing powder adheres to the surface of the curable binder resin layer by spraying. The amount of the brazing material powder applied is determined by the brazing strength and the like required in the design of the equipment. Normally, when using aluminum alloy brazing material,
It is preferably from 10 g / m2 to 150 g / m2. If the coating amount is too small, a fillet of a sufficient size will not be formed, and if it is too large, the resin itself will be almost completely covered with the brazing material powder, making the adhesion itself difficult. When Si powder is used, the coating amount may be 3 g / m 2 or more.

In the present invention, the brazing filler metal powder that has not adhered when sprayed can be recovered and reused. Since the brazing filler metal is time-consuming and expensive to manufacture, the yield of the brazing filler metal is improved by collection. After attaching the brazing material, the resin is cured. Although the method of curing the resin varies depending on the type of the resin, typical curing methods include thermal curing, ultraviolet curing, and electron beam curing. Among them, ultraviolet curing and thermal curing are preferred from the viewpoint of equipment cost and operability. In addition, ultraviolet curing is particularly preferable in terms of productivity. In the present invention, the amount of the resin to be used is small compared to the method of mixing the brazing material powder with the resin, and therefore, the curing is easy.

In another aspect of the present invention, an embodiment in which the binder resin is further applied after the brazing material powder is sprayed to cure the resin can be adopted. According to this, since the entire surface of the brazing material is covered with the binder, the peeling resistance of the brazing material is improved. After the brazing material is sprayed and the resin is once cured, when applying the binder resin,
The coating method may be performed by dipping, roll coater, spray coating or the like. When performed before the hardening treatment, the spray method is preferred from the viewpoint that the movement of the brazing material powder does not occur. Thus, the resin covering the surface is cured in the same manner as in the method described above. In this case, the amount of resin applied is
10 mg / m2 after curing (with solvent evaporated)
It is preferably at least 3 g / m2. If it is less than 10 mg / m 2, no effect of improving the peeling resistance of the brazing material is recognized. 3g
Even if it exceeds / m2, the effect of improving the peeling resistance is not changed, so that the binder is wasted, and it takes a long time to cure the curable binder resin, so that the productivity of coating decreases.

When the step of applying the curable binder resin again after spraying the brazing material as described above, the amount of the binder applied first can be reduced.
The amount of the curable binder resin used as a whole does not greatly increase. In the present invention, the flux powder may be sprayed simultaneously with or before and after the spraying of the brazing material. The flux is used to break the oxide film on the surface of the aluminum alloy during brazing and to enable brazing, and typical examples include fluxes of fluoride type, Cs type, and chloride type. It is not limited. If the particle size of the flux in this case is equal to the particle size of Si described above, no problem occurs. In the case where the brazing material and the flux are applied together as described above, there is an advantage that the application of the flux is not required at the time of brazing.

The amount of flux applied is usually 0.5 g / m 2
Not less than 30 g / m2. The flux may be previously mixed with the curable binder. The flux is different from the brazing filler metal powder, and its specific gravity is close to the specific gravity of the curable binder resin, so that sedimentation does not easily occur even when mixed with the curable binder resin. This is because there is no need to control. The use of the brazing material-coated metal material manufactured according to the present invention is not particularly limited. Tubes or strips are particularly suitable as materials for heat exchangers in motor vehicles and the like.

[0016]

Next, the present invention will be described in more detail with reference to examples. Example 1 A thermosetting acrylic resin-based binder solution using toluene as a solvent by dipping over the entire length of a strip (about 10 km in length) having a thickness of 0.08 mm and a width of 16 mm obtained by adding 1% Zn to 3003 alloy. Was continuously applied so that the resin weight after drying was 4 g / m 2, and then classified so that the particle diameter was in the range of 10 μm to 30 μm.
1-14% Si alloy (containing 0.6 wt% or less of Fe as an inevitable impurity and 0.05 wt% or less of each element such as Cu, Zu, Mn, and Ti) brazing material powder (manufactured by a gas atomizing method) ) With an adhesion amount of 30 g /
Nitrogen gas was continuously sprayed as a carrier gas so as to obtain m2. The brazing alloy powder that did not adhere to the surface of the strip when sprayed was recovered and used. After the binder and the brazing filler metal powder were applied to the surface in this way, the resin was cured by heating to 200 ° C. in an air furnace to evaporate the solvent. Corrugating was performed at a pitch of 10 mm in height and 2 mm apart from the top, 1/4, center, 3/4, and last portions of the obtained strip in the length direction. Using this corrugated strip material as a fin material, 20 hills were used, combined with a 3003 alloy plate having a width of 16 mm and a thickness of 1 mm to assemble a one-step core, applying a fluoride-based flux, and 600 ° C. in a nitrogen gas atmosphere. A 3 minute braze heat was applied. The brazing property was evaluated based on the fin adhesion rate. That is, the fins are peeled off from the tube, and the adhesion rate of the completely bonded one is set to 100%, and the unbonded part is (length of the bonded part) / (length of the bonded part) + Length of unbonded portion) was multiplied by 100 to obtain an adhesion rate (%). Table 1 shows the results. As is clear from the results in Table 1, the strip of the present invention has good brazing properties and is stable at any part in the length direction. In addition, since the brazing filler metal powder can be recovered, the adhesion yield exceeded 90%.

COMPARATIVE EXAMPLE 1 A strip material having a thickness of 0.08 mm and a width of 16 mm (about 10 km in length) obtained by adding 1% Zn to the same 3003 alloy as in Example 1.
Then, an acrylic binder solution using toluene as a solvent (the same binder as in Example 1) was added to Al-14% S.
The binder solution containing the brazing filler metal powder mixed with the i-alloy powder (the same powder as in Example 1) was continuously applied by a dipping method. In the coating, the binder concentration, the ratio of the brazing powder in the binder solution, the line speed, and the like were adjusted so that the amount of the brazing powder attached at the start of coating was 30 g / m2. As described above, the binder powder containing the brazing filler metal powder was applied to the surface of the strip material, and then heated to 200 ° C. in an air furnace to evaporate the solvent and harden the resin.

The lengthwise leading end of the obtained strip material, 1/4
From the part, the center part, the ／ part, and the final part, corrugating was performed at a pitch of 10 mm and a pitch of 2 mm. This corrugated strip is used as a fin material for 20 mountains and has a width of 1
A single-stage core was assembled by combining with a 3003 alloy plate having a thickness of 6 mm and a thickness of 1 mm, a flux of a fluoride system was applied, and a brazing heat of 600 ° C. × 3 minutes was performed in a nitrogen gas atmosphere. The brazing property was evaluated based on the fin adhesion rate. That is,
Peel off the fin from the tube and set the adhesion rate to 100% for those that are completely bonded, and for those with unbonded parts,
(Length of bonded portion) / (Length of bonded portion + Length of non-bonded portion) multiplied by 100 to obtain adhesion rate (%)
And Table 1 shows the results.

[0019]

[Table 1]

As is clear from the results shown in Table 1, in this method, the adhesive ratio does not reach 100% even at the head, and the binder concentration of the binder solution increases as the coating proceeds. On the contrary, since the brazing material powder sinks to the bottom of the container, the amount of the brazing material attached decreases, and the brazing property decreases. Furthermore, since the brazing material remaining in the container after application cannot be reused, the yield of the brazing powder was 50% or less.

Example 2 A strip material having a thickness of 0.25 mm and a width of 37 mm (having a length of about 4
km) on the surface not clad with 15% Al-3% Zn alloy. The brazing material was continuously coated by the procedure shown in 2-1 to 2-8. Unless otherwise specified in the brazing filler metal powders shown in the table, Fe is 0.6 wt% or less, Cu, Z
Elements such as n, Mn, and Ti are each contained in an amount of 0.05 wt% or less. In addition, the brazing alloy powder which did not adhere to the surface of the strip when the brazing powder was sprayed was recovered and used. The obtained strip material was subjected to ERW processing to produce a flat tube having a width of 16 mm with the brazing material side as an outer surface, and a length of 200 m.
m, and cut the top part, 1/4 part,
Tubes cut from positions corresponding to the central part, 、 ３ part, and final part were collected. The tube was combined with an alloy fin obtained by adding 1% Zn to a corrugated 3003 alloy having a thickness of 0.07 mm to assemble a single-stage core. A fluoride-based flux was applied to the obtained core (without applying flux to a tube to which flux had already been applied), and brazing was performed under a heating condition of 595 ° C. × 3.5 minutes in a nitrogen atmosphere. .

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

The brazing property was evaluated by the fin adhesion rate. That is, the fins are peeled off from the tube, and the adhesion rate of the completely bonded one is set to 100%, and the unbonded part is (length of the bonded part) / (length of the bonded part) + Length of unbonded portion) was multiplied by 100 to obtain an adhesion rate (%). Table 5 shows the results. As is clear from the results in Table 5, the strip material of the present invention has good brazing properties at any site. Further, when the flux is applied together with the brazing, the application of the flux at the time of brazing is unnecessary. In addition, since the brazing filler metal powder can be recovered, the adhesion yield exceeded 90%.

Next, on one side of the 3003 alloy, Al-3% Zn
Alloy thickness 15% clad 0.25mm width 37mm
15% of Al-3% Zn alloy of strip material (length about 4km)
Experiment No. of Table 4 was applied to the surface not clad. Although the brazing material was continuously coated according to the procedure shown in 2-9, a stable amount of the brazing material adhered by the roll coater could not be secured because the film thickness was large. A brazing test was performed on the obtained strip in exactly the same manner as in the experimental example. Table 5 shows the results.
Shown in

[0027]

[Table 5]

As is clear from the results in Table 5, in this experimental example, the adhesion amount of the brazing filler metal powder varies, and the adhesion rate is not stable. Furthermore, since the brazing filler metal containing binder solution remaining after application is settled at the bottom of the container,
It could not be reused and the yield of brazing filler metal powder was 60% or less.

Example 3 A multi-hole flat tube (1.8 mm in height, 16 mm in width, about 2 km in length, 12 holes) obtained by hot-extruding a cylindrical billet of JIS A1050 aluminum as shown in Tables 6 and 7 Experiment No. The brazing material was continuously coated by the procedure shown in 3-1 to 3-7. Unless otherwise specified in the brazing material powders shown in the table, unavoidable impurities were Fe
0.6 wt% or less, and elements such as Cu, Zn, Mn, and Ti, respectively, in an amount of 0.05 wt% or less. In addition, the brazing alloy powder which did not adhere to the surface of the strip when the brazing powder was sprayed was recovered and used. Experiment No. In 3-7, the powder cannot be recovered due to the dipping method. The obtained tube is wound on a reel having a diameter of 400 mm, and then subjected to direct processing to be cut into pieces each having a length of 580 mm. The cut tube was collected from the position corresponding to the final part. The obtained multi-hole tube was subjected to a corrugated Al-0.5Si-1% Fe-0.5% Ni-2 having a thickness of 0.07 mm.
The heat exchanger core shown in FIG. 1 was assembled in combination with a% Zn alloy fin and a 3003 alloy header pipe. A fluoride-based flux is applied to the obtained core (with no flux applied when the flux is applied together with a solder), and heated at 595 ° C. for 3.5 minutes in a nitrogen atmosphere. Brazed.

[0030]

[Table 6]

[0031]

[Table 7]

The brazing property was evaluated in the same manner as in Example 1 by the fin adhesion rate. Table 8 shows the results.

[0033]

[Table 8]

As is clear from the results in Table 8, the experiment N
o. The tubes manufactured in 3-1 to 3-6 have good brazing properties at any positions. On the contrary,
Experiment No. In 3-7, stable brazing could not be performed because the film thickness was large. In particular, when approaching the final part of the brazing material coating step, precipitation and aggregation of the binder occurred in the dipping layer, resulting in unstable brazing properties. Experiment No. 3-1 to 3-
In the case where the flux is applied together with the solder in step 6, the application of the flux at the time of brazing is unnecessary. In these experimental examples, the adhesion yield exceeded 90% because the brazing filler metal powder could be recovered. In 3-7, since a large amount of the binder solution (a binder solution in which the brazing filler metal powder was mixed) remained in the dipping container, the yield of the brazing filler metal powder was 60% or less.

[0035]

As described above, according to the method of the present invention, a metal material having a uniform distribution of the coated brazing material can be industrially manufactured with high productivity, and the brazing stability can be improved. In addition, when the brazing material powder is applied together with the brazing, the application of the flux at the time of brazing is unnecessary, which has an industrially remarkable effect.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a parallel flow type condenser.

[Explanation of symbols]

 1 Extruded multi-hole flat tube 2 Fin 3 Header pipe

Claims (7)

[Claims] 1. A method for producing a brazing material-coated metal material, comprising applying a curable binder resin solution to the surface of a metal material, spraying a brazing material powder, and then curing the binder resin. 2. A brazing material-coated metal material, comprising: applying a curable binder resin solution to the surface of a metal material, spraying a brazing material powder, further applying the binder resin, and then curing the binder resin. Manufacturing method. 3. The method for producing a brazing material-coated metal material according to claim 1, wherein a flux powder is sprayed at the same time as or before or after the spraying of the brazing material. 4. The method for producing a brazing filler metal material according to claim 1, wherein a flux is previously mixed with the curable binder resin. 5. The method for producing a brazing filler metal material according to claim 1, wherein the metal material and the brazing material are Al-based alloys. 6. The method according to claim 3, wherein the brazing filler metal powder is Si powder. 7. The method for producing a brazing material-coated metal material according to claim 1, wherein the obtained brazing material-coated metal material is wound into a coil shape.