US2437606A - Method and apparatus for oiling sheet metal - Google Patents

Description

March 9, 1948. G. A. KAUFMAN METHQD AND APPARATUS FOB. OILING SHEET M ETAL Fil d Nov. 27. 1944 2 Sheets-Sheei 1 INVENTOR George/4. Kaufman March 9, 1948. G, A, KAUFMAN 2,437,606 j THOD AND APPARATUS FOR OILING SHEET METAL I 2 Sheets-Sheet 2 Filed Nov. 27, 1944 INVENTOR fi e/99A. Kaufman MW 44 M111,

Patented Mar. 9, i948 METHOD AND APPARATUS FOR OILING SHEET METAL George A. Kaufman,

Jones & Laughlin Aliquippa, Pa.,

Steel Corporation,

assignor to Pittsburgh, Pa., a corporation of Pennsylvania Application November 2'7,

3 Claims. (01. 117-93) This invention relates to the oiling of sheet metal, such as tinplate, in continuous strip, and more particularly to a method and apparatus for applying a very thin film of oil to electrotinned strip.

An object of the invention is to provide a method and apparatus for applying to sheet metal, such as tinplate, a film of oil of uniform thickness sufficient to protect the metal during storage and shipment, but not so thick as to interfere with subsequent processing.

In the manufacture of tinplate, for example, it is highly desirable to have a thin film of oil on the surface of the plate when it is packaged for shipment, for several reasons. If the plate is packaged without oiling and is stored for a period of time prior to use, it may rustin spots, particularly if stored in damp or humid surroundings. If the plate is packaged without oiling and roughly handled in shipment the individual sheets or plates may rub upon one another sufficiently to produce black spots on the coating-a form of tin oXide objectionable to the user. And finally, unoiled sheets, after having been stacked, tend to stick together and so jam the automatic feeding machines used by can makers.

For certain applications, however, the thickness of this oil film must be kept to a minimum. Light weight tinplate-that is, plate with a thin tin coating-is quite generally lacquered or enamelled by the can maker for a number of types of cans, and this lacquer or enamel does not adhere well if an appreciable amount of oil is found on the tinplate. Thus the tinplate producer encounters difficulty in applying enough oil to protect the plate in shipment but not so much as to impair lacquer adhesion.

This problem is most acute with electrolytically tinned sheets. The great bulk of electrolytic tinplate is made with thin tin coatings, on the order of /2 to lbs. of tin per base box of plate. A base box of tinplate contains sheets totalling 217.78 sq. ft. of surface, one side. Nearly all of this product is lacquered by the can maker. Although oil is widely used in the brightening stage of the manufacture of electrolytic tinplate, the film left on the plate is generally not the weight and type desired by the user and therefore the finished plate must be oiled as a separate step in the production process. It is with this step in the manufacture of tinplate that my invention is concerned.

Electrolytic tinplate is all produced as continuous strip, and is only sheared to sheets as the last step before sorting and packaging. It is 6 therefore highly desirable 1944, Serial No. 565,315

to apply the oil to the strip. Because of this, the methods of controlling the oil thickness employed for hot dip tinplate, which is produced commercially as separate sheets-are not readily applicable, and Conventional as oiling by spraying or dipping the sheet, or dipping followed by branning to remove excess oil, have been adapted to continuous strip but have been found incapable of proclosing a uniform oil film of the desired thinness. The method has been reversed, and a fixed quantity of oil added to the bran, through which the strip is then run, but also without the desired result. Other processes have been tried, but it can be said of the oil films they deposit, that those providing protection impair lacquer adhesion, and those which do not impair lacquer adhesion do not provide sufficient protection. Prior to my invention, no method of oiling electrolytically tinned strip was known which deposited a film sufficient to provide protection in storage and transit but thin enough not to impair lacquer adhesion.

In the application of Robert A. Woofter and Robert H. Smith, Serial No. 565,314, filed November 27, 1944, now Patent No. 2,429,862, issued October 28,1947, there is disclosed a continuous process for oiling strip which produces an exceedingly t in but continuous film of oil on the metal surface, sufficient to provide protection in storage and transit, and not detrimental to lacquer adhesion. That process comprises atomizing oil with air to form a mist of oil particles suspended in air, heating such a mist to vaporize the oil particles, and finally causing the oil vapor so formed to condense on the surfaces of the this manner they can deposit on the film so thin that only .1 of a gram of oil is sufficient for a base box, or one pound of oil covers 2,000,000 sq. ft. of surface; such a film has been found to have no detriment-a1 effect on This film, moreover, is so uniform, and covers the surface of the tinplate so completely that it provides adequate protection to the plate. Such tinplate, with a uniformly distributed oil film of this thickness, is a new article of manufacture, never before available.

The present invention is an improvement over the Woofter and Smith invention. According to my invention, the condensation of the oil vapor on the sheet metal is made more efficient by carrying out the condensation in an electrostatic field. By this means the molecules of oil vapor are charged with a high potential with recontinuous tial difference is created between the molecules of the vapor and the strip, the time necessary for the vapor to be in contact with the strip Furthermore, the condenon the strip is so com- In the accompanying drawings which illustrate a preferred embodiment of my invention parts being shown in elevation and Figure 2 is a vertical section through one of the spraying devices.

My process is most conveniently carried out at a point in the tin line just before the final coiler, where the strip can be made to run vertically. As shown in Figure l,

8 to a coiler 9. In traveling upwardly between the rollers 5 and E, the strip passes first through a vaporizing chamber it! On each side of the strip and located in the vaporizing chamber is a row of atomizing nozzles a stream of oil mist ticles suspended in air. The may not be heated; in the case of an oil such as palm oil or paraiiin which is a solid at ordinary temperatures sufficient heat to liquify the oil is, of course, essential. It is generally desirable to heat the air to insure its dryness but neither the oil nor air is heated to a temperature much higher than 200 F. Inany case after passing through the spray nozzles E5, the mist or oil-air mixture is probably cooled to a temperature near room temperature by the expansion. The nozzles it are preferably placed about 6 to 7 inches from the strip and the streams of oil mist are directed as shown bythe reference numeral I6 and impinge first upon the bafiies I! and then rebound to baffles are directed toward the strip pinge on the strip.

In order to accelerate condensation of the oil vapors on the strip, I arrange a pair of fine wires 49 in the bottom of the hood M on each side of the strip 2. The Wires 40 are connected to the potential is applied, charged in the electrostatic field and all, if not all, the vapor is caused to condense on the strip.

The thickness of oil film deposited is controlled both by the amount of oil fed to the spray determined by the operating conditions of the is taken up or let out For a uniform oil film it is necessary that the oil supply the tin line. drive itself,

made by a rheostat in the D. 0. power supply satisfactory with the wires about 1 strip on each side. up therefore has a strength of between 10,060 volts. per inch.

The amount of heat necessary to introduce into the baiiies 5'. and i3 is quite easily determined from observation. If the bafiies are observed to be wet, not all the oil is being vaporized, and more heat is required. If the bafiies are too hot, some oil will burn, producing smoke which tected. For cottonseed oil, we bafilc, if electrically watts per inch width of the heaters the electrical is easily de find that each heated, requires about of strip. The temperature may be controlled by controlling power input, or by he spray. At higher air pressures more air is blown upon the heaters, thus cooling them.

A preferred type of spray or atomizer is illustrated in Figure 2, this figure being a vertical cross section through one of the spray heads. A number of spray heads are arranged on each side of the strip so as to cover the width of the be sprayed. A block or housing 20 is formed With a trough 2. which receives oil flowing through pipes 22, 23 and The oil flows through an opening 25 in the pipe 24 into the trough 2i and the overflow passes over a dam 26 into a sump or return 2'! from which it is re- (not shown). The housin an electrical turned to a pump may be provided, if desired, with heater 28 for heating 29 are mounted on a shaft 30, the shaft being driven directly or indirectly from the driving means for the strip so that the shaft and wheels 29 rotate in accordance with the speed of passage of the strip through the apparatus. A nozzle 3! is located above each wheel 29. The nozzle is provided with a passage 32 controlled by a valve 33, the passage communicating with a pipe 34 which supplies air. Adjacent the outlet of the air passage 32 is a plate 35 which directs the air downwardly past an atomizing tube 35 formed in the nozzle. The tube 36 is located adjacent a shoulder 31.

As the wheel 22 is rotated, it picks up a film of oil from the oil in the trough 2i and raises it to a point adjacent the tube 36 where the film of oil is scraped off by the shoulder 31 and flows through the tube 35 in a very fine stream. The oil issuing from the tube 36 is atomized by the air flowing through the passage 38 forming a mist of oil droplets or particles suspended in air. This stream of mist is directed against the heated baflles l1 and is as previously described and the mist is condensed on the strip 2. In the embodiment shown, the air nozzles 31 and discs 29 are spaced about 1 inch apart over the width of the strip. This spray produces a very uniform oil mist because the rotating discs 29 bring up oil to the air stream at a rate varying only with the speed of rotation of the shaft 30. The amount of oil atomized is thus easily controlled by controlling the speed of rotation of the shaft.

The pressure of air required is low, 2 to 4 lbs. being satisfactory, except when the air flow is also used to control the baliie temperature as previously mentioned. Under such conditions, pressures up to 12 lbs. have been employed, with satisfactory results.

The type of oil used depends, of course, on the customers requirements. Palm oil is occasionally used by me for electrolytic plate, but cottonseed oil is more generally employed. For some purposes a synthetic compound such as dibutyl sebacate is more desirable. Parafiin oil, and hydrogenated fish oil have also been used occasionally. It is understood that my process is capable of utilizing any oil required and is not limited as to type of lubricant.

It will be understood also that my process is not confined to tinplate, but is applicable to any metal plate or strip which requires a thin, uniform film of oil.

The invention is not limited to the preferred embodiment which has been given merely for purposes of illustration, but may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. The method of continuously applying a thin, uniform film of oil to both sides of continuous strip metal comprising moving the strip vertical- 1y, continuously supplying oil at a predetermined rate to a plurality of air streams disposed on both sides of the strip, atomizing the oil with the air to form a mist of oil particles suspended in air,

plurality of heated surfaces interposed between the air streams and strip in such manner that no oil particles impinge on the strip, maintaining the heated surfaces at a temperature sufficient to vaporize the oil particles, and charging the molecules of the vapor to a high potential with respect to the strip by causing them to pass through an electrostatic field having a strength between 8000 and 10,000 volts per inch, whereby said molecules are attracted toward the strip and condensed thereon.

chamber, a cooling chamber, means for passing the sheet metal continuously through the vaporizing chamber and cooling chamber, means in the vaporizing chamber for atomizing oil with air to form a mist of oil particles suspended in air, at least one bafile interposed between said atomizing means and the strip, and heating means for maintaining the baiiic at a temperature sufficient to vaporize the oil particles, the baffle being arranged so that no oil particles can impinge on the sheet metal, and means for charging the molecules of vapor to a high potential with respect to the strip, whereby the molecules are attracted toward the strip and condensed thereon.

3. Apparatus for applying a uniform film of oil to sheet metal, which comprises a vaporizing chamber, a cooling chamber, means for passing the sheet metal continuously through the vaporizing chamber and cooling chamber, means in the vaporizing chamber for atomizing oil with air to form a mist of oil particles suspended in air, the atomizing means comprising a plurality of nozzles each having an air passage and a wheel asso ciated with each air nozzle and adapted upon rotation to carry a film of oil adjacent the outlet of the air passage and be atomized, at least one baiiie interposed between said atomizing means and the strip, and heating means for maintaining the baffle at a temperature sufficient to vaporize the oil particles, the baille being arranged so that impinge on the sheet metal, and means for charging the molecules of vapor to a high potential with respect to the strip, whereby the molecules are attracted toward the strip and condensed thereon.

GEORGE A. KAUFMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 2,334,648 Ransburg NOV. 16, 1943

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