US2074498A - Method and apparatus for coating - Google Patents

Description

March 23, 1937. R. J. WEAN METHOD AND APPARATUS FOR COATING Filed Dec. 21, 1935 2 Sheets-Sheet l March 23, 1937. R. J. WEAN 2,074,498

METHOD AND APPARATUS FOR COATING Filed Dec. 21, 1935 2 Sheets-Sheet 2 T, i I.

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Patented 23, 193? aortas;

2,ii74i,i98 4 Mnrnon nan arraan'rns non coa'rrna Application December 21, 1935, Serial No. 55,597

1 Claim.

This invention relates to the art of coating and in particular to the maintenance of a clean surface on a bath of coating fluid. The invention pertains specifically to the tinning of sheet steel 5 and will be described with reference thereto although it has other applications as well.

Tinning of steel sheets is usually carried on by passing the sheets longitudinally through a socalled tin-pot in which a bath of molten tin is maintained in a fluid condition. During the progress of the operation, floating accumulations known as scrufi form on the surface of the tin bath. This scrufi is apt to adhere to the sheet metal passing through the bath, and mar the surface finish thereof.

It is an object of my invention, therefore, to provide a method and apparatus for removing the scruff from the surface of the bath to prevent such marring of the sheets. I also make arrangements for the collections of the scruff at one side of the bath for easy removal therefrom.

In accordance with my invention, I provide a I screw conveyor extending across the bath and having spiral flights thereon projecting down into 25 the tin. The conveyor is driven by any convenient means and is effective to move the scruff on the surface of the tin toward the side of the bath in a direction transverse to that in which the material moves therethrough.

The invention will be more completely described with reference to the accompanying drawings and the novel features thereof pointed out in the appended claim.

In the drawings:

Figure 1 is a central longitudinal sectional view taken through a tin-pot having the apparatus of the invention incorporated therein;

Fig. 2 is a sectional view along the line II-II of Fig. 1; and

screw conveyor.

Referring now in detail to the drawings, a tinpot It is'substantially of conventional form except for the invention to be described and comprises a container H with entering feed rolls I2 suitably journaled therein at one end and exit rolls l3 similarly positioned at the other end. The entering feed rolls I! are mounted in a frame composed of side plates l4 connected by cross members IS. The exit rolls iii are similarly journaled in a frame IS. A curved guide I! L. effective to directsheets from the feed rolls to the exit rolls.

The container H includes a well It for the- 55 molten tin and a chamber IQ for a layer of palm Fig. 3 is an enlarged view of a portion of the (Cl. ill-12.7)

1 oil which floats on the tin and through which the coated sheets pass after leaving the tin bath.

The level of the tin at the exit end of the pot is shown at 20 and the level. of the palm oil thereabove is indicated at 2!. At the entering end of the pot, the level of the tin is indicated at 22. A layer of molten flux floats thereabove. Immersion heaters 23 are mounted adjacent the entering end of the pot to heat the contents thereof.

The path of a sheet through the pot is indicated by the line 24. In order to maintain a clean surface on the tin bath adjacent the point at which the material enters the tin, I provide a screw conveyor 25 journaled in the side plates it. The conveyor is arranged to be driven by any convenient means, for example, the same drive which operates the feed-in and exit rolls I2 and I3. The conveyor 25 has spiral flights 26 thereon.

' As shown in Fig. 3 the flights are dished in the direction in which it is desired that the scruff be moved. The flights may all be of the same pitch or the flights on opposite sides of the center of the conveyor may be of opposite pitch, as shown in Fig. 2, whereby to cause movement of the scruff from substantially the middle of the bath toward the sides thereof. Scruff boxes 21 are disposed between the side plates M and the side walls of a container Ii adjacent the ends of the conveyor 25. The latter thus delivers scruff to the boxes 27 from which it may be easily removed.

If desired, 8. second conveyor 28 similar to that shown at 2'5 may be mounted as shown, on the opposite side of the path of the material traversing the pot. By this means a clean surface is assured throughout a fairly wide zone adjacent the point at which the material enters the bath. The conveyors 25 and 28 are preferably driven in opposite directions as indicated by the arrows in Fig. 2.

In operation, the screw conveyors serve to move all scruff or other floating accumulations toward the side of the bath and thus maintain a clean space therebetween for the entry of the material being coated. The conveyors also serve to circulate the flux floating on the entering side of the bath so that fresh flux is presented to the incoming material at all times.

The advantages of the method and apparatus described, in effecting a thorough cleaning of the surface of the bath adjacent the point of entry of material thereinto, will be readily appreciated. Adherence of the scruff to the material is prevented so that a larger percentage of the tinned sheets have a perfect surface. The invention involves only a slight change in the mechanin scope of the appended claim. s

What- I claim is:

aomwa In a coating apparatus including a container for a fluid coating material, means for removing floating accumulations from the surface of said material comprising a screw conveyor having its axis substantially parallel to said surface and helical flights extending into said surface, and

a scruff box adjacent one end of the conveyor.

the conveyor being effective to feed said accumulations into said scruff box.

RAYMOND J WEANt

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