US2104102A - Method for degreasing - Google Patents

Description

Jan. 4, 1.938. F. F. RUTHVEN METHOD FOR .DEGREAS ING Filed May-4, 1 955 2 Sheets-Sheet 1 AIINVE-NTIORY.

. EZJWI'IKFIIMSfiZIIWII ATTQRNEYS Jan. 4, 1938. F; F RQTHVEN 2,104,102

METHOD FOR DEGREASING Filed May 4, 1935 2 Sheets-Sheet 2 n lmlllh MINI ammirww n A I 9 Lu & I A

Patented Jan. 4, 1938 I METHOD FOR DEGREASING Frederick Francis Ruthven, Toronto, Ontario, Ganada, assignor, by mesne assignments, to Aluminium Laboratories Limited. Montreal, Quebec, Canada, a corporation of Canada 7 Application May 4, 1935, Serial No. 19,869

Claims. (01. 87-6) This invention relates to method and apparatus for degreasing articles and various goods such as have become soiled in'their manufacture, and require cleaning prior to further processing as 5 for plating, galvanizing, lacquering, brass-finishto accomplish degreasing as rapidly and as eco- 6 ing, and for all other treatments for which the nomically as possible. My invention contemsurface of articles must be free from grease, oils, plates applying heat to the article being treated, waxes, resins, and foreign accumulation adhering either prior or subsequent to its immersion in the to such articles because of the presence of such cleaning solvent, at such a rate and in such quanmaterials. Solvents of the kind suitable -for de-- tity that the article will attain a temperature of 1 0 greasing include trichlorethylene, ethylene diat least the vapor temperature of thesolvent chloride, carbon tetrachloride, tetrachlorethylene after the article leaves the bath of boiling solvent and mixtures thereof, and other substances se-. so that the article is devoid of a film of solvent lectable in accordance with the properties of the as well as of greasy material when it leaves the articles to be cleaned and the character of the vapor atmosphere. materials to be dissolved, and in keeping with While the. apparatus illustrated may be adaptcommon practice I shall refer to the results 010- ed to convey baskets of individual articles through tainable by the methods of the present invention the degreasing process, in its present form it is n as degreasing irrespective of the particular classiparticularly suited for the rapid degreasing of fication of the materials removed so long as they metallic sheet material. are soluble in the kinds of solvents which are .In its main features it consists of a tank or usable in commercial practice for cleaning purcontainer 9 which is provided with a heating coil poses, as for example, the solvents referredto IIJ near its bottom for heating the solvent H. hereinabove. With this understanding, my in- A coil of sheet material to be cleaned is mounted ventionrelates more particularly to the degre'asupon a supply spool or spindle I2 and the sheet ing of articles which have sufficient heat capacis guided over the guide roll |3, into the tank ity to maintain a temperature at least as high as and under bath roll hi, to heated roll l5, idler 16, the vapor temperature of the solvent for a period and over roll I1 to a rewind drum la. The sheet of time sufficiently long to enable the withdrawal is advanced over the rolls by the application of of the articles from a vapor atmosphere of the driving power to the rewind drum l8 so that 30 solvent, degreased and clean, after having passed the sheet is maintained under tension as it passes through hot solvent. through the apparatus. A squeegee IS with felt- It is among the objects of the invention to procovered surfaces may be used for maintaining vide method and means whereby articles ,may be tautness in the sheet throughout its course of 3-3 completely degreased in less elapsed time than travel in thetank. heretofore attainable, and to assure freedom of Bath roll l l'is partly immersed in hot con solvent on the degreased articles. densate contained within a pan it so that the Other and more detailed advantages and 010- sheet will be thoroughly washed in the hot con= jects will appear more fully in the accompanying densate as it'passes under the roll. If desired, a

40 description and claims and from the annexed pair of buffer rolls 2! may be provided beyond drawings in which is shown an apparatus emthe exit edge of the pan to remove excess solution. ploying the principle underlying the present in- The coil It may be heated by passing steam vention and designed. for the degreasing of metherethrough, and the heat given up by the coils tallic sheet material. keeps the solvent at the bottom of the tank in In the drawings:- ebullition and causes continuous vaporization. 45

Fig. 1 is a plan of apparatus for degreasing All of the space above the boiling solvent up to, metallic sheet material. coils 22 is filled with solvent vapor so that heated Fig.2 is a longitudinal section of'the apparoll Iii is immersed in a vapor atmosphere. The ratus, and cooling coils which are in the upper portion of 50 Fig. 3 is a section on line 3-3 of Fig. 2. the tank prevent loss of vapor from the tank. 5o

A common practice. heretofore employed for These cooling coils are mounted around the indegreasing metallic products in course of manuside of the wall of the tank and cold water is facture has been to immerse such products in a supplied thereto for producing the cooling effect bath of boiling solvent, such as trichlorethylene, desired. The vapor linein the tank is in the and then in a vapor atmosphere of the solvent vicinity of the lower tiers of the cooling coils. 55

v for a sufficient period of time to dry the products. The vapor which comes in contact with the cool- For this purpose articles may be handled in bulk ing coils condenses and collects in a gutter 25% in wire containers or passed through the solvent just below the coils. This gutter is a source of m and vapor mediums on chain conveyors. This supply of condensate of pure solvent for the liquid procedure has served satisfactorily so long as time was not of the essence, but with limited space or for the treatment of articles which require very little handling, asf'for example, coiled sheet metal, foil, cable, wire, etc., it is desirable solvent bath in pan 2!! in which roll l4 depends.

receiving distilled solvent and the greasy or otherwise dirty solvent is overflown from the pan and is collected in the sump 25 at the bottom of the tank from whence it may be manually removed.

when the apparatus is not in operation.

Preferably the outer wall of the tank is in,- sulated as at 26 up to the cooling section of the tank so as to preserve vapor conditions in the vapor bath.; Under ordinary conditions there will be no overflow of vapor from within the tank but a cover 32 may be used to prevent the waiting away of vapor by air disturbances on the'outside of the tank.

The roll I5 is heated by any suitable means as by passing steam therethrough, orby gas or electricity, and the temperature of the roll should be maintained such as to heat the sheet sufficiently to prevent the condensation of the vapor upon the sheet before it leaves the apparatus. The heat provided by the heated roll produces a condition of superheated vapor in the vicinity of the heated roll. Such; factors as the specific heat of the material being degreased, the quantity or thickness of the material, the desired rate of' passage of the material through the vapor atmosphere, as well as the vapor temperature of the solvent shouldbe considered in determining the temperature to which the heated roll must be heated. For degreasing sheet aluminum by the use of trichlorethylene I have been able to increase the rate of degreasing very materially with the temperature of the steam in the heated roll' at about-350 F.

The heated roll is mounted upon bearings 21,

28 which are preferably disposed outside of the tank. The heated roll may be made of any suitable material and I have obtained satisfactory results in degreasing sheet aluminum with an iron roll. Especially when the surface of the roll is of a harder material than that of the sheet it should. have a polished surface and be driven. In the of solvent can be exceeded many times without carrying over any solvent with the sheet being cleaned.

While I have disclosed a preferred form of ap- I paratus by which my method may be utilized for degreasing sheet material, it is to be noted that an important feature of my method is in pro-.

viding heat in sufilcient quantity to the article being cleaned to prevent such cooling of the article as to permit condensation on the article before it leaves the vapor atmosphere. In additionto the described manner of applying heat, I have obtained satisfactory results in cleaning sheet' aluminum by heating it before its'entrance into the tank. For articles other than those which may be wound upon a drum and which maybe heated by means of a roller, other provision may be made for heating the articles before entering the degreasing apparatus. For example, castings requiring to be degreased prior to plating may I bepassed through a tunnel furnace which would lipipefl serves to conduct the condensate from the .gutterto the bath. The pan is continually ture of the vapor bath.

impart to them enough heat for them to emerge from the degreasing apparatus at a temperature hotter than the solvent vapor.

f It should be noted that if the sheet or other This will produce a flushing action of liquid and improvedcleaning conditions. Because of this it is considered preferable to heat'the sheet or other article after it enters the vapor atmosphere' in the degreasing apparatus.

What is claimed is:

- 1. In the method of removing oily or greasymaterial from articles, the steps comprising subjecting an article to be degreased to the action of a liquid solvent bath, passing the article from the liquid solvent bath into a vapor bath of said liquid solvent, heating the article to a temperature above the temperature of said vapor bath while the article is within said vapor'bath, and removing the article from the vapor bath before the temperature of the article drops down to the temperature of the vapor bath.

2. In the method of removing oily or. greasy material from articles, the steps comprising subjecting an article to be degreased to the action of a vapor bath of a solvent for the material on the article with the article at a temperature below the temperature of the vapor bath, heating the article to a temperature above the temperature of the vapor bath before the article leaves the vapor bath, and removing the article from the the article at a temperature below the temperature of the vapor bath, raising the temperature of the article to a'temperature above the temperature of the surrounding vapor bath by heating the article by conduction while the article is immersed in the vapor bath, and removing the article from. the vapor bath before the temperature of the article drops down to the tempera- 4. In the method of removing oily or greasy material from a metallic strip, the steps comprising subjecting a metallic strip to be degreased to the action ofa vapor bath derived from a liquid solvent for the greasy material on the metallic strip, heating the strip while within said vapor bath to a temperature in excess of the temperature of the vapor bath, and ridding all trace of solvent film fromthe strip by removing the strip from said vapor bath while the strip is at a temperature in excess of thetemperature of the vapor bath from which it is being removed.

5. In the method of removing oily or greasy material from articles, the, stepscomprising introducing an article within a vapor bath of a solvent for the material on the article, passing the article through a zonecf vapor superheated with respect to temperature of said bath and contained within said vapor bath, maintaining the. articlewithin said superheated zone to raise the temperature of the arttfeie above that of the vapor bath, and thereafter removing the articie from the vapor bath before the temperature of the article drops'down to the temperature of the vapor bath.

FREDERICK FRANCIS RUTI-IVEN.

. vapor bath before the temperature .of the article i

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