Abstract A fin and plate type heat exchanger made by a vacuum brazing process comprises dish-shaped plates positioned in confronting relation to form refrigerant passages therebetween, and in backto-back relation to form air passages therethrough. Heat exchange fins are disposed in the air passages and extend between the backs of adjacent plates. Spacer fins are disposed in the refrigerant passages between the plates to serve as structural reinforcing members and to afford turbulent flow of the refrigerant to enhance heat exchange. Prior to assembly and brazing, the spacer fins are formed by lancing and convoluting a thin blank, such as aluminum plate, from which burrs must be removed. The blank is coated with a clad, such as an alloy of aluminum, magnesium and silicon, prior to lancing and convoluting, so that, in the brazing operation, the clad alloy forms a low melting temperature eutectic alloy with the material of the burrs effectively dissolving them, and leaving a smooth surface upon solidification.
The method according to claim 1, and characterized in that said metal comprises essentially aluminum, and said alloy comprises essentially aluminum and silicon.
Claim 2
Dependent Claim
43 words
The method according to claim 1, and characterized in that said metal comprises an alloy of about 98.8 percent aluminum and 1.2 percent manganese, and said alloy coating comprises about 7 percent silicon, 2 to 3 percent magnesium, and a balance of aluminum.
Claim 3
Dependent Claim
28 words
The method according to claim 1, and characterized further by the inclusion of the step of subjecting said coated metal sheet to a vacuum as it is heated.
Claim 4
Dependent Claim
31 words
The method according to claim 4, and further characterized in that said vacuum is in the order of from about 1 X 10 4 torr to 1 X 10 6 torr.
Claim 5
Dependent Claim
58 words
The method according to claim 2, wherein said alloy has a melting temperature in the range from about 1,070* F to about 1, 130* F and heating to melt said coating is carried out at a temperature of about 1,130* F, said method characterized further in that said metal sheet is heated in the presence of a vacuum.