Metal deforming – Process – Deforming sheet metal
Patent
1980-01-28
1982-08-31
Larson, Lowell A.
Metal deforming
Process
Deforming sheet metal
72375, 72404, 72469, 72 17, 72 31, B21D 1302, B21D 3708, B21D 4302, B21D 5304
Patent
active
043465820
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates generally to heat exchangers and more particularly to a method for use in the formation of thin metal plates used in such heat exchangers.
2. Background Art
Primary surface recuperators have been developed which incorporate thin alloy metal sheets that have been corrugated or folded to produce passages on both sides of each sheet. These passages serve to direct the flow of air and hot gasses, and heat is transferred directly through the sheets which are suitably welded together to prevent the flow of air into the gas passages. The corrugations in the sheet surface also serve to support adjacent sheets in the assembly.
Before the sheets are assembled, edge portions of the sheets are crushed to provide flattened header sections which will facilitate the cross flow of fluid. These header sections at each end of the sheet receive or deliver the air or gas from or to the appropriate passages of the assembly.
A stacked plate heat exchanger of the type described is illustrated by U.S. Pat. No. 3,759,323 to Harry J. Dawson et al. In fabricating heat exchangers of this type, difficulties have been encountered in flattening the header sections. The header sections extend transversely to the corrugations, and as the corrugations in the header sections are flattened, the corrugations expand and often completely or partially block the fluid passages defined by adjacent corrugations. Attempts to alleviate this problem have not been satisfactory. For example, comb-like devices have been employed in an attempt to open the blocked passages following the crushing of the header section corrugations, but since the blockages are irregularly spaced, the regularly spaced comb devices sometimes contribute to the blockage instead of removing it. Also the sheets have been staggered so that the transition blockage does not occur all at one zone and the fluid can pass over the blocked region, but this solution to the problem results in the use of excess heat exchanger material.
The foregoing illustrates the limitations of the known prior art. Thus it is apparent that it would be advantageous to provide an alternative to the prior art.
DISCLOSURE OF THE INVENTION
In one aspect the present invention provides a novel method for flattening corrugated heat exchanger plates to form header sections which includes separately and progressively crushing the corrugations in a transition zone between the fluid passages and a header section before forming the remainder of the header section.
Another aspect of the present invention is to provide a novel apparatus for flattening corrugated heat exchanger plates to form header sections which includes opposed die members for progressively crushing the corrugations in a transition zone, each die member having blades which are maintained on either side of a corrugation to limit the ability of the corrugation to expand or flare outwardly during the crushing operation.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. It is to be expressly understood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a corrugated heat exchanger plate which is to be flattened to form header sections in accordance with the present invention;
FIG. 2 is a diagrammatic illustration of the die assembly of the present invention for receiving a moving heat exchanger plate;
FIG. 3 is a cross sectional view of the die set used for the die assembly of FIG. 2;
FIG. 4 is a cross sectional view of one die slot and one die blade of the die set of FIG. 3 taken along lines 4--4 of FIG. 3;
FIG. 5 is a detailed illustration of the detent switches used for the die assembly of FIG. 2; and
FIG. 6 is a circuit diagram of the control circuit for the die assembly of FIG. 2.
BEST MODE FOR CARRYING OUT THE INVENTION
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REFERENCES:
patent: 1462475 (1923-07-01), Atkinson
patent: 2988033 (1961-06-01), Gapp
patent: 3759323 (1973-09-01), Dawson et al.
patent: 4022050 (1977-05-01), Davis et al.
patent: 4109503 (1978-08-01), Francon et al.
Caterpillar Tractor Co.
Larson Lowell A.
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