JPH01262090A - Brazing sheet for structural member of drawn cup type heat exchanger having good brazing property - Google Patents

Abstract

PURPOSE:To improve a brazing property by regulating the surface roughness of one face at least of the Al alloy brazing filler metal cladded on the one face or both faces of an Al alloy core bar in the specified mean roughness and max. roughness respectively in the orthogonal direction with the rolling direction. CONSTITUTION:In the case of the manufacture of the brazing sheet for a drawn cup type heat exchanger the final cold rolling at least in a cold rolling stage is executed by using the rolling roll whose surface is subjected to bright finishing or specular finishing. The surface roughness is made in <=0.4mm mean roughness (Ra) and <=2.5mm max. roughness (Rmax) in the orthogonal direction with the rolling direction. In the fluid tube stock formed from the brazing sheet of this state and excellent brazing property is shown without being effected by brazing conditions. A good fillet is then formed at the inner side of the mating face (brazing joint) and the drawn cup type heat exchanger passing a pressure resistant test sufficiently can be manufactured with good yield.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention has excellent brazing properties and is particularly suitable for use as a fluid tube sheet material that is a structural member of a doron cup type heat exchanger. This invention relates to alloy brazing sheets.

[Conventional technology]

In recent years, due to the demand for lighter weight, more compact size, and higher performance in transportation equipment such as automobiles, Dron cup type heat exchangers have become popular as heat exchangers for radiators, car cooler condensers, evaporators, oil coolers, intercoolers, etc. They are starting to be loaded at the department.

This doron cup type heat exchanger consists of a pair of halved fluid tube sheet materials, which are structural members,
Similarly, it is manufactured by stacking one layer or two or more layers of fin material alternately, fixing this stacked body with a stainless steel jig, and performing flux brazing or vacuum brazing.

In addition, the above fluid tube sheet material conforms to JIS3003
AfI is made by cladding a brazing material made of Ajl1 alloy such as 4045 or 4004 on one or both sides of a core material made of Aρ alloy such as 4045 or 4004.
It is molded from an alloy brazing sheet by press working.

[Problem to be solved by the invention]

However, in the above-mentioned Drone cup type heat exchanger, a relatively large pressure is applied to the fluid flowing through it, so it is required that the joints of the fluid tube sheets are completely brazed. Fluid tube sheet materials, which are conventionally composed of brazed sheets, are particularly susceptible to problems such as when the vacuum in a vacuum brazing furnace is not high enough or when the dew point of the atmospheric gas in an inert atmosphere brazing furnace is low enough. Fillet formation on the inside of the mating surface (brazed joint) is good when brazing under poor conditions, such as when the oil etc. attached during press processing before brazing is not sufficiently cleaned. However, the pressure resistance test after brazing may fail, and in many cases, the pressure resistance test after brazing may fail.
%, and since these rejected products cannot be repaired, they are sometimes disposed of in lots, resulting in a low manufacturing yield.

[Means for Solving the Problems] Therefore, from the above-mentioned viewpoint, the inventors of the present invention have developed a method for manufacturing a doron cup type heat exchanger, especially when used as a structural member of the same, especially as a fluid tube sheet material. As a result of our research to develop a brazing sheet that exhibits good brazing properties without being affected by brazing conditions, we found that the surface roughness of the brazing sheets that make up conventional brazing sheets is Average roughness (Ra) in direction:
0.4-0.8 um.

Maximum roughness (Rmax): 3-4tμm, but
When manufacturing a brazing sheet, at least the final cold rolling in the cold rolling process is performed using a rolling roll whose surface is brightly finished or mirror finished, and the surface roughness is averaged in the direction perpendicular to the rolling direction. Roughness (Ra): 0.4 μs or less, maximum roughness (R
max): 2.5 ts or less, the fluid tube sheet +a formed from the brazing sheet in this state will not be affected by the brazing conditions, that is, even under the poor brazing conditions mentioned above. , we are able to manufacture Dron cup type heat exchangers with high yields that exhibit excellent brazing properties and form a good fillet on the inside of the brazed joint (mating surface), which satisfactorily passes the pressure test. We have obtained the knowledge that it is possible to do so.

The present invention has been made based on the above knowledge, and provides a brazing sheet formed by cladding an Aρ alloy brazing material on one or both sides of an A11 alloy core material, wherein the surface roughness of at least one side of the Al alloy brazing material is In the direction perpendicular to the rolling direction, average roughness (Ra): 0.4 μm or less, maximum roughness (R
max): 2.5 am or less,
The present invention is characterized by a brazing sheet that has improved brazing properties and is suitable for use as a structural member of a doron cup heat exchanger, particularly as a fluid tube sheet material.

Therefore, as in the above-mentioned conventional plazing-on-1, the surface roughness of the brazing filler metal or the Ra in the direction perpendicular to the rolling direction
If it exceeds 0.4 μs and RIIIax exceeds 2.5 μs, it becomes impossible to ensure good brazing.

〔Example〕

Next, the brazing sheet of the present invention will be specifically explained using examples.

3003 alloy (composition: Aρ-1,23%Mn-0,12%Cu) as Aρ alloy for core abrasion using normal melting method.
, 3005 alloy (composition, Aρ-1, 31%Mn-0,
313% Mg), and 6951 alloy (composition, 8Ω-0
,62%Mg -0J8%S j -0,22%Cu
, 4004 alloy (composition = Δg - 9, 36% SI - 143% Mg) and 4004 alloy (composition = Δg - 9, 36% SI - 143% Mg)
045 alloy (composition, 8β-10.2% Si) was melted,
After forming an ingot with a thickness of 414+n+n using a vertical semi-continuous casting device, the temperature was maintained at 590°C for 12 hours for 3003 and 3005 alloy ingots, and 560°C for 12 hours for 6951 alloy ingot. The Aρ alloy ingots for brazing were each subjected to homogenization heat treatment at 480°C for 12 hours, and then both sides of these ingots were coated with a thickness of 7 mm on each side, and ingots for brazing were processed. The Al alloy ingot was hot rolled to a thickness of 50+++n, and in this state, the brazing filler metal Ap was applied to both sides of the core Al alloy ingot in the combinations shown in Table 1. The combined pre-hot-rolled sheets are stacked to a total thickness of 500+++n, which is then hot rolled at a rolling start temperature of 480°C to form a 7mm thick cladding material. is 5mm→3.2mm+2.1mm→
1.4n+m→1. 5 stages of cold rolling with a thickness of 0 mm, and in this cold rolling, when the thickness reached 5++ μm, intermediate annealing was performed in an inert gas atmosphere at a temperature of 350 ° C. for 2 hours, In addition, cold rolling with a thickness of 1.4 mm and 1.0 mm was carried out using various rolling rolls with bright or mirror-finished roll surfaces and adjusted surface roughness, and finally rolled using inert gas. Brazing sheets 1 to 12 of the present invention having the surface roughness shown in Table 1 were manufactured by annealing in an atmosphere at a temperature of 350° C. for 2 hours.

Also, for the purpose of comparison, the thickness in the above cold rolling: 1
．． Conventional rolling mills with the same surface roughness shown in Table 1 under the same conditions except that rolling of 4 mm and 0 mm were carried out using ordinary rolling rolls, that is, various rolling rolls with mill-finished surfaces. Brazing sheets 1 to 4 were manufactured, respectively.

Next, from the various brazing sheets obtained as a result, as shown in the schematic longitudinal cross-sectional view in Fig. 1, a fluid tube sheet was modified into a fluid tube sheet for a Dron cup heat exchanger, with an inner diameter of 40+nmφ and a depth of 18mm. A cup-shaped test piece with a center hole of diameter +IO++nnφ in the center of the bottom and a cup-shaped test piece without the center hole were press-molded, and these were stacked in three sets, and in this state, they were placed in an inert gas atmosphere. , Temperature 1 Table 1 Flux soldering under the condition of holding at 600'C for 5 minutes (=
1 digit or I X lO'torr in vacuum, temperature
Vacuum brazing is performed on GOO'C under the condition of holding for 3 minutes to produce a brazed laminate with a structure modified to a Dron cup heat exchanger, and this brazing is then applied to the center hole at the bottom of the laminate. A connecting pipe was attached by torch brazing, this pipe was connected to a pressure tester, a pressure test was conducted using water pressure, and the maximum pressure at which peeling occurred on the brazed surface of the test piece was measured. . These results are shown in Table 1.

[Effects of the Invention] From the results shown in Table 1, the brazed laminates manufactured using the brazing sheets 1 to 12 of the present invention all exhibited high pressure resistance, and the brazing of the brazing surfaces (brazed joints) The attachment is good and a good fillet is formed on the inside, whereas conventional brazing sheets 1 to 1
In the brazed laminate manufactured in 4, the wax (=I
It is clear that the strength of the brazed joint is low, it can only withstand relatively low internal pressure, and it is not completely soldered.

As mentioned above, the brazing sheet of the present invention has excellent brazing properties, and when used as a fluid tube sheet brazing material for a doron cup heat exchanger that requires particularly high brazing strength, the brazing sheet of the present invention has excellent brazing properties. This brings about industrially useful effects such as a drastic reduction in the number of defective products caused by defects and a marked improvement in product yield.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing a brazed laminate having a structure that is a modified version of a doron cup heat exchanger.

Claims (1)

[Claims] (1) In a brazing sheet formed by cladding an Al alloy brazing material on one or both sides of an Al alloy core material, the surface roughness of at least one side of the Al alloy brazing material is determined by the average roughness in the direction perpendicular to the rolling direction. (Ra): 0.4 μm or less; Maximum roughness (Rmax): 2.5 μm or less. A brazing sheet for a structural member of a doron cup heat exchanger having good brazing properties.