Metal fusion bonding – Process – Plural joints
Reexamination Certificate
1999-07-28
2001-03-13
Ryan, Patrick (Department: 1725)
Metal fusion bonding
Process
Plural joints
C228S175000, C228S217000, C228S223000
Reexamination Certificate
active
06199750
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a core of a heat exchanger for use with a heat exchanger employed in an automobile, such as a condenser, an evaporator, a heater core, or a radiator.
The present application is based on Japanese Patent Applications No. Hei. 10-239171 and 10-239175, which are incorporated herein by reference.
2. Description of the Related Art
A core of a heat exchanger, such as an evaporator, is constituted by arranging in an alternating manner a plurality of corrugated outer fins made of aluminum material and a plurality of flat tubes made of aluminum material. Each of the tubes is formed by bead-butting two tube plates and brazing the thus-butted plates.
The core is usually manufactured as follows: First, slime-like flux comprising, as dispersion medium, polybutene such as that described in, e.g., Japanese Patent Publication No. Hei. 4-322896, is applied to the entirety of the surfaces of the two tube plates constituting the tube. The two tube plates are assembled into a tube while their internal surfaces become mutually opposed. The flux-coated tubes and the outer fines are arranged one by one. The tubes and outer fines, which are arranged alternately, are heated in a heating furnace, to thereby sublime the dispersion medium of flux and activate and fuse brazing filler metal. As a result, the tubes, each being assembled from the tube plates, are brazed together, and the tube plates connected to the top peaks of the corrugated outer fin are brazed, to thereby constitute the core.
As mentioned above, slime-like flux is sprayed onto the entirety of the surfaces of each tube plate, to thereby wastefully consume flux and disadvantageously add to cost.
After the respective tube plates have been coated with flux, two tube plates are assembled to a tube, and an outer fin is connected to each side of the tube. In this way, the tubes and the outer fins are arranged in an alternate manner. Assembly of the tube plates into the single tube and arrangement of the tubes and the outer fins are performed continuously, thus deteriorating working efficiency. Further, if a worker touches the flux-coated surface of the tube plate during the operation, the flux may be disadvantageously scraped away from the surface.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method of manufacturing a core of a heat exchanger which enables manufacture of a core at reduced cost by eliminating waste of flux, improvements in the efficiency of stacking operation, and eliminating scraping of flux from the tube plate.
According to the present invention, there is provided a heat exchanger core manufacturing method of alternately arranging and brazing together a plurality of corrugated outer fins formed from aluminum material and a plurality of flat tubes, wherein each of the flat tubes is formed by assembly of two tube plates and by brazing butt bead faces provided on the respective tube plates. In the method, the top peaks of the outer fin are coated with slime-like flux, and a sandwich unit is assembled from the outer fin and the tube plates by attaching the tube plates to the respective sides of the outer fin such that the surfaces of the tube plates having the butt bead faces formed thereon face inward. The butt bead faces on the respective tube plates on either side of the sandwich unit is coated with the slime-like flux. A plurality of sandwich units whose tube plates are coated with the flux are stacked into a layer, and the assembly is heated in a heating furnace, to thereby braze together the tube plate pairs and the tube plates connected to the outer fin.
Preferably, of the outer fin and the tube plates only the tube plates are formed from clad material whose surface is coated with a layer of brazing filler metal.
The method for manufacturing a core of a heat exchanger according to the present invention involves application of the slime-like flux to solely the top peaks of the corrugated outer fins and the butt bead faces on the respective tube plates. The areas other than those required to be brazed are not coated with the flux, thus eliminating waste of the flux and advantageous manufacture of the core at reduced cost.
In a process before the process for forming the sandwich unit from the outer fin and the tube plates, the flux is not applied to the tube plates, and hence the tube plates can be handled easily. Even after assembly of the sandwich unit, the surfaces of the respective tube plates on either side of the sandwich unit are not coated with the flux. Hence, the sandwich unit can be handled easily, and there can be prevented staining of surrounding facilities, which would otherwise be caused by the flux.
The butt bead faces on the respective tube plates of the sandwich unit are coated with the slime-like flux, and the sandwich units are stacked in a layer. There is little chance of the worker touching the flux-coated surfaces of the tube plates on either side of the sandwich unit, thus preventing scraping off of the flux adhering to the tube plates.
Further, as mentioned above, once the sandwich unit has been constituted of the outer fin and the tube plates, the tube plates on respective sides of the sandwich unit are coated with flux. So long as the sandwich units are stacked one after another, a core can be constituted by stacking the outer fins and the coolant tubes in an alternating manner, thus improving the efficiency of staking operation and productivity.
Of the outer fin and the tube plates, only the tube plates are formed from clad material, thus realizing further cost reduction, thus enabling manufacture of a core of a heat exchanger at reduced cost.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
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Fujiyoshi Tatsuya
Kouno Makoto
Matsunami Ryoji
Calsonic Kansei Corporation
Foley & Lardner
Pittman Zidia T.
Ryan Patrick
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