US2213117A - Coating machine - Google Patents

Description

g- 9 P. o. BLACKMORE 2,213,117

COATING MACHINE Filed July 7. 1957 INVENTOR 391/; i. izac/r/va/as i if? Patented Aug. 27, 1940 PATENT ,OFFlCE COATING MACHINE Paul 0. Blackmore, Cincinnati, Ohio, assignor to Interchemical Corporation, New York, N. Y.,

a corporation of Ohio Application July 7, 1937, Serial No. 152,303

1 Claim.

This invention relates toroll coating machines,

and has particular reference to a new type of roll coating machine, in which the coating roll is situated above the work to be coated, and travels 5 in a reverse direction to that of the work.

A great many flat objects which are coated with complete coats of paint and similar compositions may be advantageously coated with special coating machines, which feed the coatl ing material to a roller in a fairly uniform layer,

from which it is transferred to the object to be coated. Such objects as sheet metal signs, the

elevated, portions of embossed license tags, tin

- can blanks, artificial lumber such as Masonite,"

l and the like, are very often coated in this fashion.

In the conventional type of coating machine, two opposed rollers, one rotating clockwise and the other counter-clockwise, drive the work 20 through the-machine. Coating material is fed to the top roller by means of distributing rollers, so as to insure a reasonably even film. The principal disadvantage of this type of coating machine is that the coacting material must be sum- 25 ciently slow drying so as not to dry on the distributing rollers. A second disadvantage is that this system deposits the coating in the form of a wavy ribbed surface, and the coating composition must flow out before drying if a pleasing an appearance is to be obtained. .Careful formulation of coating compositions is an essential if successfu1 results are to be obtained; and materials which can be used successfully on the conventional prior art coating machines are often 3 expensive, because of the exacting requirements.

I have devised a coating machine which operates on an entirely different principle, and which can use practically any film-forming coating composition.

In the drawing, Figure 1 is a front elevation of my machine, Figure 2 is a section through the line 2-2 of Figure l, and Figure 3 is a detail fragmentary view of the gearing,

My machine comprises a base I, with a pair 45 of standards 2 rising from the base-spaced apart. An upper roll 3, preferably made of metal, is carried on a shaft 4 journalled in hearings in the standards; a lower roll 5, which may be corrugated, or of composition or rubber, is like- 50 wise carried on a shaft 6 joumalled in bearings in the standards, preferably so as to be movable with respect to the upper roll, to permit of various degrees of clearance between the rolls. Gears I and l are mounted on shafts l and 6, and are driven by a gear I, mounted on. a shaft 'of desired thickness will form on the roll.

It set in the standards. The gear 9 may be driven in any desired manner. As indicated in Figure 3, the two rolls move in the same direction, so that their opposed surfaces move in opposite directions. 5

Arms ii extend out from the standards 2, and between them support a doctor blade l2, so arranged as to provide a reservoir 13 for coatin material between-the doctor blade and the roll. Material is fed to this reservoir from a largertank or drum l5 placed above the reservoir at a rate equal to that at which it is being consumed, thus keeping fresh material in reservoir l3 at all times. t

The, edge of the doctor blade is preferably 15 rounded to a semicircle, indicated at M. This doctor blade deposits a film on the coating roll which is much smoother and freer from roping than that deposited by the feed rolls of the prior art roll coaters. The edge is rounded primarily to permit of easier cleaning, as the conventional prior art knife edge picks up skins very readily, and when cleaned with a spatula or knife nicks readily, so that the desired smoothness of film is lost. 1

Similar arms it support a scraper bladell just above the reservoir l3, while arms l8 support a scraper is mounted on the bottom roll.

A pair of supplementary rolls 20 and H may be advantageously mounted on the feed side of the machine when deformable sheets of material which are not perfectly plane are to be fed to the machine. l or example, bagasse board such as Masonite is very rarely plane; by feeding it between two pressure rollers as indicated, the slight warping'is eliminated, and a plane board is fed to the machine, which can be coated perfectly without streaking or without leaving. the extreme edges uncoated because of poor contact with the coating roll. 40

In the operation of the device, the rolls are set so that the work to be coated will fit into the clearance space between the rolls. Coating material is fed into the pocket 13, the doctor blade being set so that on rotation of .the roll a fllmrfiz e rolls are started, and the sheet of material is fed into the space between the rolls. The lower roll is preferably made of composition (although it may be corrugated), so that it makes frictional contact with the sheet and drives it through the rolls. The upper roll, the periphery of which is traveling in a reverse direction to that of the material, deposits its film 22 onto the sheet in a smooth film. The action of the reverse rotation is similar to that of a knife edge, in that it lays down the film and at the same time smooths it' out. i

The auxiliary scrapers I1 and I9 are used to remove undesirable coating material from the rolls. The top scraper prevents excess dry coating on the upper roll from contaminating the supply in the reservoir; while the bottom scraper removes paint which accidentally falls on the bottom roll, so that it does not lubricate the bottom roll and thus prevent it from driving the sheets through the machine.

While my device is very simple to operate and construct, its principal advantage is in its operation. The only portion of the coating material exposed in the form of a film, before the sheets are coated, is the film 22; and that only during part of a revolution (the distancefrom the doctor blade i2 to the surface of the material being coated) at which point it is completely removed. Because of this, rather quick drying material may be used. Similarly, the wiping action of the reverse roll smooths out the film, and eliminates the necessity for the use of a coating material which will flow well before setting up.

In the practice of my invention, it is essential that the coating roll be placed above the work. By so doing, the film 22 may be reduced to minimum area, by placing the doctor blade as indicated. Furthermore, the work may be picked up mechanically as it comes off the machine, onto a conveyor, with the coated side up. A third, and

principal advantage, lies in the fact that the coating composition is not constantly agitated, as is the case with an underfeed device, where the rotation sprays the material into the air and causes thickening, especially with rapid drying materials.

By the use of my apparatus, it is possible to coat sheets of rigid material with the ordinary inexpensive fast-drying coating compositions now used .for spray application, as against prior art roll coaters which require the use of compositions formulated with slow solvents to promote after flow, obviously at the sacrifice of fast drying.

Where it is desired to coat paper and the like in webs, the lower driving roll 5 may obviously be replaced by web-feeding rolls of any conventional type.

Minor changes can, of course, be made in the apparatus without departing from the scope of my invention, which is defined in the accompanyfng claim.

I claim:

An apparatus for coating comprising a smooth roll, a doctor blade mounted on said roll and having a rounded edge bearing against said roll to form a reservoir for coating composition between the doctor blade and the roll, and means for passing an object under the coating roll and in contact therewith in a direction of travel opposite that of the roll as it passes the object.

PAUL O. BLACKJHORE.

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