US1872015A - Drying method - Google Patents

Description

Aug. 16, 1932- D. SHANKLIN 1,872,015

DRYINGYMETHOD Filed Sept. 50. 1929 If: ventor DunbarL. Shanklin. 61 W M w/6W J Aftfys.

Patented Aug. 16, 1 932 UNITED STATES PATENT OFFICE DUNBAR L. SHANKLIN,

OF WAVERLY, MASSACHUSETTS, ASSIGNOR TO DEWEY AND MASSACHUSETTS DRYING METHOD Application filed September 30,1929. Serial No. 396,051.

This invention relates to drying desiccable moist deposits on articles superposed on each other to form a stack, and has for its object the rapid, economical, and perfect drying of such deposits which by reason of the stacked relation of the articles themselves lie in a protected situation between adjacent articles lying in direct contact with each other, and are thus difficult of access by drying media such as circulating hot air. As an example of such articles and their desiccable deposits, I take the stamped, circular, channeled discs of tin plate used as can-ends, in the marginal channels of which is deposited a viscous fluid sealing material, such as latex composition, which must be nearly 1t not completely rid of its contained liquid (water in the case of latex composition) before the can-ends are a finished article of manufacture.

In the drawing hereto annexed, which il lustrates my invention,

Fig. 1 is a vertical section through three can-ends of a stack;

Fig. 2 is a vertical section through a drying apparatus; this drawing is diagrammatic, and-shows no structural details; and

Fig. 3 is a horizontal section at the line 33 inFig. 2.

The can-ends, which I take as examples of the type of articles to which-my drying method is adapted, are circular stamped discs (1-) of tin plate, the stamping operation pro ducing the marginal channels 2 in which the viscous, plastic, liquid-containing sealing material, desiccable and to be dried, is deposited.

Since the can-ends are very nearly identical in shape and dimensions, it is obvious, that when stacked as shown in Fig. 1 only the deposit S on the'topmost can-end will be effectively accessible to drying-air circulated in the usual manner in the space wherein the stack is placed. Contact, or very close approximation to it between the shoulder portions 3 and lips 4 of adjacent can-ends produces substantially closed chambers for the sealing material S, from which evaporation of contained moisture is very slow.

Moreover, under the conditlons prevailing when the stack is subjected only to a general circulation of'drying-air, local condensation of moisture evaporated from sealing mate-- the individual can-ends inevitably possess assist to produce crevices permeable to air under conditions of pressure-differential.

My improved method therefore is characterized by the direction of jets of hot dryingair, at quite high velocity, against one side of a stack of can-ends, so that the air impinges on the lines of contact between the assembled can-ends producing on that side of the stack an air pressure higher than that at another side thereof. The arrest of the air stream at the side of the stack of canends diminishes the velocity-pressure and raises the static pressure; the flow of air through and then'away from the stack produces the converse translation from static to velocity pressure, so that, as between the sides of the stack there is established a static pressure differential of suflicient magnitude to induce a lateral air-drift in the space between each adjacent pair of can-ends, the air penetrating between the can-ends on the jet-impingement side, and escaping an onother side of the stack. In its transit across the inter-can-end spaces, the air absorbs moisture from the sealing material, prevents any recondensation on metal surfaces; and on.

escaping at a low pressure side of the stack carries evaporated moisture with it.

Referring to Figs. 2 and 3, of the drawing, which illustrates indiagram an apparatus which has effectively demonstrated my method; there is provided a chamber, or passage 7, open at both ends, and an endless conveyor belt 8 on which stacks 5, of can-ends are arranged, preferably in two rows in staggered relation as shown in Fig. 3, to be conveyed through the drying chamber 7 in the direction indicated by the arrow in Fig. 3. This chamber, or passage 7, is surrounded by the inner wallsof an air duct, which is divided.

into three terminal chambers, chambers 9 extending along the sides of the drying passage 7, and the depending middle chamber 11. Heated drying air is delivered to these terminals from an induct 6. The, inner walls of terminals 9, and both walls of terminal 11, are provided with jet orifices 10, which are preferably formed as narrow vertical slits. The drying-air escapes through either open end of'the chamameter, with adeposit of 100 mg. of latexcomposition containing approximately 36% solids of which one-half are mineral fillers in their marginal channels, a jet-velocity of 3000 feet per minute, of air at 250 F. and 35 to humidity, and a translation rate of 3 inches per minute for the stacks'of canends, with a total drying period of 15 minutes produces satisfactory results, with pronounc ed economy of )time and heating cost. 40 The apparatus herein described is the subject of an application for Letters Patent of the United States, Serial No. 396,052 filed concurrently herewith, and is reserved for claim therein. a

I claim:

1. The method of drying desiccable deposits on plate articles of substantially standardized size and shape, characterized by can-ends, which comprises arranging the articles in symmetrically contacting, super posed relationship, thus providing a stack exteriorly characterized by relatively large nnperforate surfaces and relatively minute posits on plate I articles of substantially standardized size and shape, characterized by can-ends which comprises arranging the articles in symmetrically contacting, superposed relationship in a plurality of spaced "stacks, each of which is exteriorly characterized by relatively large imperforate surfaces and relatively minute spaces between the edges of the articles, generating intense drying gas jets directing the jets in generally horizontal directions against the stacks so that the gas impinging upon the relativoly large surfaces affords regions of positive static pressure, While the major portion of the air passes around the stacks causing a relatively low static pressure on sides opposite that of gas impingement, and thus causing sufiicient air to seep through the minute spaces and between the articles to remove moisture from the deposits while precluding the formation of drops of mois-' ture on the surfaces of the articles.

3. The method of. drying desiccable deposits in the channels of can-ends of like size and shape, which comprises arranging the can-ends in symmetrically contacting superposed relation in a pluralit of spaced stacks, each of which is exterlorly characterized by relatively large imperforate surfacesand relatively minute spaces between the edges of the articles, generating intense drying gas gets, directing the jets in generally horizontal directions against opposite sides of the stacks so that the gas impinging upon the relatively large surfaces affords regions of positive static pressure, conveying the stacks past the jets so that successive surfaces of the stacks are exposed to successive jets, thereby causing the major portion of the air to pass around the stacks to cause a relatively low static pressure on the sides opposite that of gas impingements, while causing sufiicient air to seep' through the minute spaces and between the articles to remove moisture from the deposits, and precluding the formation of drops of moisture on the surfaces of the articles.

Signed by me at Cambridge, Massachusetts this 27th day of September, 1929.

DUNBAR L. SHANKLIN.

spaces between the edges of the articles, gencrating an intense drying gas jet, directing the jet against one side of the stack in a substantially horizontal direction so that the gas impinging upon the relatively large surfaces has a positive'static .pressure, and thus causing sufficient air to seep through the minute spaces and between the articles to remove moisture from the deposits while precluding the formation of drops of moisture on the surfaces of the articles.

2. The method of drying desiccable de-

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