Heat exchange – With coated – roughened or polished surface
Patent
1999-01-20
2000-04-18
Flanigan, Allen
Heat exchange
With coated, roughened or polished surface
165170, 29890039, 29463, 29458, 156292, 1563066, B21D 5118, B65D 2514
Patent
active
060503300
DESCRIPTION:
BRIEF SUMMARY
The invention concerns the making of metal tanks intended to contain at least one fluid and capable of resisting pressure, even of gas, as for example automobile fuel tanks, heating radiators for buildings or refrigerator evaporators or condensers.
To make such tanks from sheet metal blanks, said blanks are put into the form of shells having a shape adapted to the tank to be made, then said shells are assembled to form the tank.
The assembly is generally achieved by welding in the region of assembling zones or flanges in order to ensure both liquid-tightness and resistance to pressure.
In the case where the tank is intended to contain corrosive liquids, in particular in the case of fuel tanks, steel sheets are currently used which are coated with a coating for protection against internal corrosion.
The U.S. Pat. No. 4,824,736 (exactly corresponding to WO-89 02855) describes in particular a sheet steel tank coated internally with a protective coating of polypropylene modified with maleic anhydride.
The protective polymer coating maintains a very strong adherence to the sheet during and after the shaping of the shells.
But the presence on the sheet of a protective polymer coating may be troublesome for the shell welding operation: indeed, the thermal effects of the welding often produce a deterioration of the polymer coating in the vicinity of the shell-welding bead, and the internal zone of the weld bead is no longer effectively protected against corrosion.
In the case where the sheet is provided with a coating providing protection against external corrosion, the deterioration of the external coating, also consecutive to the welding operation, requires "repairing" the protective coating in the welding zone, for example by application of an external protective coating in this zone after welding.
To avoid the drawback relating to the nature of the sheet protecting coatings, one could be tempted to effect the welding of the shells under conditions adapted to limit the heating of the polymer coating to a simple melting.
Apart from the drawback of requiring a very strict control of the welding conditions, such an assembling process still leaves the welding bead itself without protection against corrosion.
The document U.S. Pat. No. 4,131,980 describes a process for making a metal tank, in which: polymer coating, provided with a polymer coating (reference 36 in FIG. 2 of the document), document).
The polymer coating applied then acts as an adhesive joint between the flanges folded for seaming.
The two assembling means, the mechanical seaming means and the chemical bonding means, collaborate.
As concerns the bonding, the use of epoxy vinyl, polyester, polyurethane, polysulphide resin is described.
This process has several drawbacks: internal corrosion in that the adhesive joint is liable to be deteriorated by the fuel flanges after the shells have been put into shape; between two shells 4' and 5' with the glue joint 6', it was found that the zone termed the triple point zone designated by the reference 7B, which corresponds to the limit of the adhesive joint 6' in contact with the two sheets 4' and 5', formed a mechanically weakening line or a rupture initiation line and that it is in this region that the risk of rupture of the tank was the highest.
The invention also concerns the making of metal heat exchanger tanks intended in particular for making evaporators and condensers of refrigerating machines.
The following description concerns more particularly evaporators of the "roll bond" (in the English language) type, but the same process may be employed for making any heat exchanger (for example: heating radiator or solar panel, condenser) employing one or more cooling or heat transfer fluids.
To make evaporators of the "roll bond" (in the English language) type: product on a zone outlining the circuit intended for the cooling fluid in the evaporator, and the two assembled sheets are hot rolled to produce locally a welding by diffusion between these two sheets, outside the zone provided with the anti-diffusion pro
REFERENCES:
patent: 3840423 (1974-10-01), Bemrose et al.
patent: 4048005 (1977-09-01), Nakagome et al.
patent: 4947548 (1990-08-01), Bentley
patent: 5271151 (1993-12-01), Wallis
Sanadres Michel
Schmit Francis
Flanigan Allen
Sollac
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