US2074798A - Apparatus for coating sheet metal - Google Patents

Description

March 23, 1937. J, R. MCELHANEY ET AL 2,074,798

APPARATUS FOR COATING SHEET METAL Filed June 22, 1934 JAMES E; MELHANEY and EOBEET STOKEE.

km '9" GYM/0 ik /x" lib/Wadi Patented Mar. 23, 1937 PATENT OFFICE APPARATUS FOR COATING SHEET METAL James R. McElhaney and Robert Stoker, Vandergrift, Pa., assignors to American Sheet and Tin Plate Company, a corporation of New Jersey Application June 22, 1934, Serial No. 731,984

6 Claims. (Cl. 91-1211) This invention relates to an apparatus for coating sheet metal, and more particularly to coating such metal with tin or terne (lead and tin), although not limited thereto.

lit is one of the objects of the present invention to smoothly and evenly coat sheet metal, as distinguished from the uneven coatings heretofore obtained, and includes the elimination of the corrugating of the metallic coating which,

in mill parlance, is known as strippers.

This and further objects will be apparent after referring to the drawing, in which;

V Figure 1 is a sectional elevation of the apparatus of the invention.

Figure 2 is a plan of the apparatus of Figure 1.

Figure 8 is a sectional view 'on the line III-III of Figure l.

Referring more particularly to the drawing,

the letter A designates a pot which is adapted to contain metallic coating compositions in a molten state.

A pair of guides I" are disposed on one side of the pot A and have asssociated therewith a pair of driven guide rolls I l, which are adapted to feed a sheet to be coated into a flux-box i2 which is provided with a guide plate l3 and contains the usual fiuxlng agents M; such as a zinc chloride solution having an excess of hydrochloric acid. As is well known in conventional tin pot practice,

this iluxing agent eiiects a final cleansing of the surface of the sheet prior to its immersion in the molten tin or terne I5 in the pot.

A pair of feed-in guides I6 are disposed in the pot A immediately below the flux-box I2, and :15 extend downwardly to a pair of immersed feed rollers H which are driven in such manner as to feed the sheet between a pair of feed-out guides it which terminate shortly below the surface of the molten tin or terne I5 on the other side of the pot A. These feed-out guides l8 are aug-' mented by a. pair of secondary guides l9 which are disposed immediately thereabove.

An oil-box 2|] is disposed immediately above the upper extremities of the guides i8 and contains a suitable oil 2|. A plurality of pairs of driven guide rolls 22 are entirely immersed in the oil 2i immediately above the guides l9.

In conventional practice, the upper pair of these rolls 22 would only be immersed in the oil in the oil-box to a point where their nips" would be exposed to the atmosphere. This is for the reason that it is desired to squeeze the excess oil from both sides of the sheets and permit it to remain in the oil-box. V

In tin plate practice the oil is so low in viscosity that it breaks or runs as the sheets emerge, and but little oil adheres thereto.

In terne practice, while the oil is heavy enough to cover a major portion of the surfaces oi. the sheets, no attempt is made to prevent the breaking of the oil film, which is due to the low viscosity of the oil. In addition, no effort is made, in terne practice, to insure the complete solidification of the metallic coating before the oil is squeezed from the sheets.

The present invention overcomes these difllcultles by feeding the sheet out of the oil-box with a smooth, continuous and unbroken metaland-oil coating thereon and maintaining the oil coating in such manner as to permit the metallic coating to solidify while thus protected. This distinguishes from the prior art, wherein the majority of the oil is immediately squeezed from the sheet and it is fed to a branner, or other cleaning device. This=causes the uneven metallic coating of sheet metal and the production of strippers.

In order to cool the metal-and-oil coated sheets, they are fed out of the oil-box 20 by the guide rolls 22, and deflected by a guide plate 26 onto an elongated cooling table B. At the remote end of this elongated cooling table B there is disposed an oil removing means C, which is made up of a pair of squeeze rolls 30. A guard 23 extends between the housings which support the ends of the guide rolls 22 and prevents foam and bubbles which are usually on the surface of the oil 2| from breaking the continuous film of oil on the sheets as they emerge from the oil-box 20. This guard 23 is in the form of a pair of plates which extend between the housings and are substantially parallel to the guide rolls 22 but slightly divergent with respect to each other. The lower, and most adjacent ends, of these plates are immersed in the oil 2| immediately above and proximate the submerged guide rolls 22.

The elongated cooling table B'is composed of an extended collector tray 3| over which there is mounted a plurality of driven spool-shaped conveyer rolls 32, each of which is made up of a pair of truncated cones with their apexes adjoining.

Due to the shape of the conveyer rolls 32 the oil film by contact.

As the metal-and-oil coated sheets S are moved along the cooling table B they are gradually and uniformly cooled by radiation. This permits the metallic coating to solidify in a. smooth and continuous state. The cooling is preferably accelerated by air under pressure from nozzles-33, which are disposed along the ends of the conveyer rolls 32, air being supplied from a main 34. The disposition of these nozzles 33 is such that the air Jets will be directed along the surfaces of the coated sheets S, rather than impinging thereon, which would have an agitating effect.

After the sheets S have reached the remote end of the cooling table'B they are assisted between the squeeze rolls 30 by a pair of guide plates 38. As the squeezed sheets S emerge from the oil removing means C they are assisted by a guide plate 31 onto a transfer means D, which is composed of a driven endless belt 40 at the other end of which is disposed the usual branner or other cleaning device.

As'shown in Figure 1, the collector tray 3|, which is disposed beneath the conveyer rolls 32, slopes toward the oil-box 20 so as to return thereto the oil removed from the metal-and-oil coated sheets S by the squeeze rolls 30. If, however, the usual palm oil were employed in the oil-box 20, it would become cracked from long contact with the highly heated sheets and, if returned to the oil-box, would render the aggregate too viscous for use.

This condition is more noticeably evident when sheets of U. S. S. gage No. 26 and heavier are processed, as they hold greater quantities of heat.

In order to obviate this difficulty, a proper viscosity of oil is maintained in the oil-box 20 despite the excess hot cracked oil which is returned by the collector tray 3lfrom the squeeze rolls 30. This is done by making such additions to the oil-box as are necessary to compensate for permanent losses resulting from the inability of the squeeze rolls 3|) to entirely remove the oil adhering to the sheets. If palm oil alone consti- 40 tilted the additions to compensate for such losses, the oil in the. oil-box would gradually become so thick as to become unworkable. If a single oil is used alone as an addition it must be of a viscosity less than palm oil, or if palm oil is used there must be added to it a non-mineral oil of less viscosity.

We have found that such additions should comprise a mixture of approximately 70 to 85 per cent palm oil and 15 to 30 per cent non-mineral oil (such as hydrogenated fish oil, cotton-seed oil or any non-mineral oil having a less natural viscosity than palm oil). This mixture can be added to the returned cracked oil and also to the remaining oil. The Saybolt viscosity of the oil in the oil-box 20 is preferably maintained approximately about 300 to 500. If these limits of percentage of mixture and viscosity are maintained the oil will be of such consistency as to provide the proper and uniform unbroken film desired.

In the teme coating of said metal by our method,v

oils of such consistency as to provide upon the metallic coating of the sheet coming therethrough a continuous unbroken film.

We have also found that the addition of an oil 75 lower in viscosity than palm oil, either alone or in combination therewith, results in less cracking or thickening than would be the case if only palm oil were used;

While we have shown and describedone speciiic embodiment of our invention, it is to be mactly thereto, since various modifications may be made without departing from the scope of our invention, as defined in the following claims.

We claim:

1. Apparatus for coating sheet metal comprising a pot containing molten metal, an oil-box associated with said pot, means for moving a sheet through said pot and said oil-box, a cooling table extending from said pot, means for moving a sheet along said cooling table while contacting only the edges thereof, and oil-removing means associated with said cooling table, said last named means being constructed and arranged to remove the majority of oil taken up by said sheet as it moves through said 011 box and return the majority of the same to the latter.

2. Apparatus for coating sheet metal comprising a pot containing molten metal, an oil-box associated with said pot, means for moving a sheet through said pot and said oil-box, a cooling table extending from said pot, means for moving a sheet along said cooling table while contacting only the edges thereof, a plurality of driven squeeze rolls associated with said cooling table, and means for returning the oil removed from said sheet by said squeeze rolls to said pot.

3. Apparatus for coating sheet metal comprising a pot containing molten metal, an oil-box associated with said pot, means for moving a sheet through said spot and said oil-box, a cooling table extending from said pot, means for moving a sheet along said cooling table while contacting only the edges thereof, means for accelerating the cooling of said sheet while on derstood that we do not wish to be limited exsaid cooling table, a plurality of driven squeeze 1 rolls associated with said cooling table, and means for returning the oil removed from said sheet by said squeeze rolls to said pot.

4. Apparatus for coating sheet metal comprising, in combination, a pot containing molten metal, means for feeding the material to be coated through said pot, a box containing oil, said box being disposed adjacent and in communication with that portion of the surface of the molten metal in said pot from which said material emerges, a pair of guide rolls immersed in the oil in said box, and a pair. of substantially vertically disposed plates extending from but having their lower edges immersed in said oil, the immersed edges of said plates being proximate said guide rolls.

5. Apparatus for coating sheet metal comprising, in combination, a pot containing molten met- 21, means for feeding the material to be coated through said pot, a box containing oil, said box being disposed adjacent and in communication with that portion of the surface of the molten metal in said pot from which said material emerges, a pair of guide rolls immersed in the oil in said box, a pair of substantially vertically disposed plates extending from but having their lower edges immersed in said oil, the immersed edges of said plates being proximate said guide rolls, a transfer table extending from said box,

and a plurality of driven squeeze rolls associated with said transfer table.

6. Apparatus for coating sheet metal comprising, .in combination, a pot containing molten metal, means for feeding the material to be immersed edges of said plates being proximate said guide rolls, a transfer table extending from said box, coolant dispensing means on said transfer table, and a plurality of driven squeeze rolls associated with said transfer table.

JAMES R MCELHANEY. ROBERT STOKER.

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