US2556954A - Glue drying apparatus and method - Google Patents

Description

Jun 12, 195 A. H. ZEIGLER ETAL GLUE DRYING APPARATUS AND METHOD 2 Sheets-Sheet 1 Filed Sept. 25 1947 June 12, 1951 A. H. ZEIGLER EI'AL GLUE DRYING APPARATUS AND METHOD 2 Sheets-Sheet 2 Filed Sept. 25, 194? Patented June 12, 1951 GLUE DRYING APPARATUS AND METHOD Albert H. Zeigler, Kenilworth, and Charles M. Harris, J13, Chicago, 111., assignors to Armour and Company, Chicago, 111., a corporation of Illinois Application September 25, 1947, Serial No. 776,051

Claims. 1

This invention relates to a gelatin drying apparatus and method. The invention is particularly useful in the drying of animal glue, vegetable glue, edible gelatine, and other forms of gelatin. It will be obvious that the process is applicable also to the treatment of other types of tacky material. For the purpose of illustrating the invention and for clarity, the process and apparatus will be described specifically in connection with the drying of glues.

In the drying of glues, great difficulty is experienced in the forming of a sheet of glue and the conveying of the same through a drier. If the sheet is dried extensively, it becomes brittle and cannot be handled effectively in the apparatus. On the other hand, if the sheet is flexible so that it can be effectively handled, the sheet is tacky and tends to cling to the conveyor mechanism upon which it is passed through a drier.

' In the handling of animal glue, including edible gelatin, the resulting glue sheet is unusually tacky and effective handling of the sheet is extremely difiicult.

An object of the present invention is toprovide apparatus and a method for the forming of gelatin sheets in large volume, while at the same time efiectivel-y drying the sheets without causing their adherence to the apparatus. A further object is to provide a means and method whereby gelatin can be formed continuously upon a roll and drawn away therefrom upon conveyor" apparatus with a continuous gelatin sheet rendered non-adherent tothe apparatus upon which it is carried away. Yet another object is toprovide means whereby the gelatin which is fed to the drying apparatus may be maintained uniform in composition by means of recycling the same. Yet another object is to provide mechanism for the handling of a glue film of relatively thick proportions upon a drying drum, together with means for maintaining the film evenly upon the roll. A still further object is to provide mechanismwhereby the dry side of the film formed upon the drying roll can be brought to rest upon the conveyor, thusto reduce the tendency of the filmor sheet to adhere to the conveyor. A still further object is to provide means whereby the object is to provide improved drying means for producing a dry glue sheet readily broken in a fragmentation machine. Other specific objects and advantages will appear as the specification proceeds.

The invention is illustrated,- in a single em bodiment, by the accompanying drawings, in which I Figure 1 is a broken longitudinal sectional new of apparatus embodying our invention; Fig. '2, a top plan View of a portion of the glue sheet withdrawn from the drying roll; Fig. 3, a greatly enlarged sectional detail view, the section being taken as indicated at line 3-3 of Fig. 2; Fig. 4, an enlarged sectional detail view of a portion of the drying roll, and glue applying and removal mechanism; and Fig. 5, a perspective view of the means employed for applying a glue film to the drying roll.

In the illustration given, It designates a drying roll having closed ends and mounted upon a hollow shaft It provided with ports [2 to which steam or other heating fluid may be admitted to heat the chamber within the roll. The roll is rotated by the usual motor-driven gear mecha-'- nism (not shown).

The roll it is preferably of large diameter, as, for example, nine feet or more. Above the roll it] is mounted a hood it with means for drawing off the vapors that are admitted during the drying of the film upon the roll.

Any suitable means for applying glue to the roll 10 may be employed. In the illustration given, we provide a container [-4 on" the righthand side of the roller, as illustrated in Figs. 1 and 4, and supported within the container is a driven roller l5 for applying a film It of glue to the roll Hi. The interior of the roll 15 is hollow, and the hollow pipe ll admits any heating fluid desired to the interior of the roll 15. In the illustration given, It designates a Valve-con trolledsteam pipe communicating with pipe [1, and 1-9 indicates a valve-controlled water pipe communicating with pipe ll.

Glue is supplied from a reservoir 20 heated by a steampipe it through a valve-controlled pipe 22 to the container it. A valve-controlled overflow pipe 23 within the container i l" main tains the glue body therein at a desired level and permits the bypassing of glue'irom the container I4 to the vessel 24' from which it is pumped through the valve controlled pipe 25 by means" of thepump it back to the reservoir 2! It is found that in the application of glue to'the roll It; a portion of the glue, after'meeting' the roll In and after being subjected to the heat thereof, rolls back into the container !4. This return of glue which has been subjected to contact with the roll it gradually changes the composition of the glue within the chamber l4 and renders the operation non-uniform. By providing a bypass constantly returning glue from chamber [4 to the reservoir 20, we find that this difficulty can be overcome and that a body of glue, uniform throughout the entire glue-drying operation, can be maintained within container I4.

Directly above the applying roll is is supported an air pipe 2? having upwardly-extending spaced openings 28 engaging a forwardly-turned baffie 29. Compressed air, discharged through pipe 27 and merged into a continuous fluid stream by the baflie 29, engages the body of glue which has just been subjected to the heatof roll i8 and cools it and supports it upon the roll It. By this means,

a heavier film is maintained upon the roll it, and

the production of the apparatus considerably increased. To the rear of the compressed air pipe 27, we provide the blowers 39 which direct a heavy stream of air against the glue film on the ascending side of the roll Hi. At this point, the roll of glue film is in substantially a vertical position and, where it contains considerable moisture, the air blast serves as a physical support for the glue, maintaining it against the roll it.

Any suitable means for removing the glue film to form a glue sheet may be provided. In the illustration given, we provide a knife 3! carried by a pivoted crank arm 32 which in turn is actuated by a threaded member 33 mounted in bracket 32%. Below the knife 3|, we provide a pipe 34 having openings 35 directed upwardly and adapted to discharge steam against the edge of the knife and the underside of the glue sheet 36 as it leaves the roll 10.

On the opposite side of the sheet 36 from the steam pipe 34, we provide a pair of pipes 37 and 38. The pipe 3? has airports 39 for directing streams of compressed air toward the point of the knife so as to cause it to impinge on the outer side of the sheet 35 as it leaves the roll. Here, the air has a surface-hardening and/or skinning effect, giving the outer surface of the glue sheet 36 a tough skin which serves as a means for supporting the sheet leaving the roll. Since the sheet is no longer heated by the roll at this point, the effect of the air is instantaneous in forming the strengthening film along the outer side of the sheet. If desired, a secondary blast of air may be directed from pipe 38 through the ports 49 upon the sheet 36 just before it passes between the chilling rolls.

. Mounted below the knife 3! and with their faces almost contacting at a line to the left of the knife 3! are the chiliing rollers 4i and 42. The rollers are driven toward each other so as to draw the sheet 36 downwardly between them and toward the conveyor apparatus. It is desirable to have the entire glue sheet adhere at all times to but one of the brine-cooled chill rolls. This is facilitated by employing rolls with different metal surfaces. For example, the roll 4! is chromium-plated and it is found that the glue sheet does not adhere to the chromium-surfaced roll. The roll 42 is a steel roll and is preferably operated at a lower temperature than the chromium-surfaced roll. With this arrangement, the glue sheet adheres entirely to the steel roll. As shown more clearly in Fig. 4, an adjustable knife 43 is effective in stripping the glue sheet and frost away from the roll 42, and the single knife is sufficient for this purpose. If desired, however,

4 each of the rolls 4| and 42 may be supplied with a doctor knife. The knife 44 for the roll 4| is ordinarily not used and tension is not supplied thereto because there is very seldom any occasion for scraping glue from the roll. The arrangement of the rolls so as to draw the glue sheet downwardly and forwardly further enhances the effectiveness of the rolls in causing the sheet to adhere solely to the roll 42.

Below the roll 42 extends an endless conveyor 45 which extends upwardly and forwardly through the first pass of the apron drier 46. The conveyor belt is constructed of galvanized T-bar girts 4? spaced at three inch intervals, the girts being arranged in inverted T-shape, as indicated best in Fig. 4. With the arrangement shown, the outer or dry side of the glue sheet is deposited upon the outer ends of the girts, while the inner or wet side of the sheet makes no contact with the conveyor. The linear speed of the conveyor is preferably adjusted to equal the peripheral speed of the chill rollers 4| and 42.

The drier may be of any suitable type or construction. In the illustration given, the casing provide in addition to the apron drier compartment 45, an intermediate compartment 48 and a lower compartment 49. Endless conveyors 45 are provided in each of the compartments to provide three passes in each tier. Air circulation fans 50 are employed, and steam-heating coils 5| are provided for supplying the necessary heat. If desired, the last two conveyors in the lower compartment 49 may be bypassed by bringing the glue sheet 36 directly upon the outlet conveyor r 52. Conveyor 52 discharges the glue onto a breaker wheel 53 of well-known construction. The broken or fragmented product falls into the outlet chute 54.

We have found that very effective results for the comminuting operation are brought about by discharging a blast of air by means of the fan 55 supported directly above conveyor 52 so that a final surface drying is accomplished by the air fan 55 just before the comminuting step. The use of such a fan, however, is not essential to method of preparation.

Any suitable temperatures in the drier may be employed. As an example, the top compartment 45, where the sheet enters, may be operated in the low temperature range of F. to F. to prevent melting; the middle tier 48 may be operated at a temperature range of F. to F; while the bottom compartment 49 may use temperatures ranging from 125 F. to F. It will be understood that these conditions are changed depending upon the type of glue being dried. In the handling of certain types of glues, it is found that no heat need be used in any of the tiers of the drier. It is not necessary that the air used in the drier be conditioned with respect to humidity.

We find that the T-bar girts on the conveyor 45 in the middle compartment 48 may be spaced more widely apart, if desired, say at six inch intervals. The conveyors 45 in each of the compartments of the dryer may be similar and, if desired, the last two conveyors may be constructed of wire screening.

As the glue sheet 35 leaves compartment 49, the cooling fan 55 impinges a blast of air upon the sheet, and such blast is highly effective when the glue sheet is very thick. Should the lue sheet be thin, the fan 55 need not be used.

In the specific illustration given, the nine-foot diameter steam drum or roll I0 is rotated in the escapes direction of the arrow shown in Fig. 1, and at a speed of about .75 R. P. M., while the chill rolls (16 inches in diameter) rotate at about 2 R. P. M. Thus, the peripheral speed of the drum is two and one-half times greaterthan the peripheral speed of the chill rolls, and we prefer that the peripheral speed of the drying roll exceed the peripheral speed of the chill rolls for the reason which will now be set out. The greater peripheral speed of the roll, coupled with the lower peripheral speed of the chilly rolls, cooperates in the forming of a crinkled or corrugated sheet of glue leaving the roll it. The crinkled or corrugated sheet is illustrated in Figs. 2 and 3.

The glue sheet, as it leaves the roll 10', tends to overlap itself and to form the irregular corrugations and crinkles illustrated in Figs. 2 and 3 and, in the subsequent drying operation, these crinkles persist and are of great value, both in the drying process and in the final product. In the drying process, the loops and bends ,or crinkles, illustrated best in Fig. 3, are highly effective in preventing the glue sheet from sticking to the conveyor, while at the same time permitting a circulation of air completely around the crinkled sheet. In the final product, the irregular or crinkled shape persists in the brokenup or comminuted material and aids greatly in causing the glue to dissolve in a water body. A mass of such fragmented glue when placed within a water body permits the water to pass quickly through the material and to dissolve the flakes. As indicated best in Fig. 3, the sheet 36 has spaced peaks or ridges 56 and corresponding hollows or recesses 51.

Operation In the operation of the process and apparatus, glue (or any other gelatin body) is supplied from the reservoir 20 to the container It, We have found that best results are obtained by using a feed liquor concentration ranging from 16% to 38% solids (84% to 62% moisture). The concentration used depends greatly upon the test and viscosity of the type of glue being dried. For example, lower test bone, chrome, and fleshing glues may be operated in the range of 28% to 38% solids, while the higher test hide glues may be fed in a concentration of 16% to 28% solids. Feed temperatures may vary from 110 F. for very low test glues to 130 F. for high test glues.

The feed or applicator roll I5 may be heated with steam or cooled with water to aid in temperature control. The roll is preferably equipped with adjustable bearings Is in order that the clearance between the roll and steam drum may be varied, this clearance determining to a certain extent the thicknes and uniformity of the glue.

The temperature of the steam-heated roll or drum It may be varied widely. We find that excellent results are obtained when the interior temperature of the steam-heated drum is about 230 F. (the temperature of saturated steam at a gauge pressure of six pounds per square inch). We have obtained good results with steam pressures of from five to ten pounds per square inch.

The applicator roll I 5 picks up a surface covering a glue and deposits it as a film l6 upon the roll l0. Compressed air is directed by the pipe 21 and deflector 29 upon the film [6 to aid in smoothing out the film and thus providing a more uniform application. The air streams emitted through the ports 28 of the pipe 21 are 6 merged in a continuous thin sheet by the bafile 29.

The blowers 30 impinge air on the drum so as to produce a smoothing of the glue film while also holding the glue upon the heated drum. Such air is extremely useful in holding glues with a grease content on the heated drum. The smoothing action of the air causes the flexible sheet to have fewer spots as might :be produced by uneven application, hence producing a more uniform product. Further, the blower air hastens the drying of the glue on the drum. The blower air may be unconditioned and employed at room temperature of from F. to F.

The rate of rotation of the steam drum or roll ii] may be varied. Excellent results have been obtained at from .75 to 1.25 R. P. M., with an internal steam pressure of 5 to 9 pounds per square inch.

The relatively high peripheral speed of the roll it in conjunction with the lower peripheral speed of the rollers 41 and 52 produced in conjunction with the doctor knife 3! a crinkling of the film as it forms the glue sheet 38. At the same time, the discharge of compressed air through pipe 31 overcomes any weakness in the product which might be produced by such crinkling and forms a skin or hardened surface on the outer side of the sheet 36, enabling the sheet to be supported by itself. The primary air pipe 3'! directs the air streams at the cutting edge of the steam drum knife. At this point, the glue has been dried on the film to a highly Viscous fluid. As the compressed air streams contact the fluid glue at the knife, a skinning or surface-hardening effect takes place, imparting sufficient strength to enable the glue to be drawn down in a continuous sheet by the chill rolls 4i and 42. Pipe 38 provides merely an auxiliary supply of air to aid the primary air in the Skinning process.

Steam, particularly during the starting up of the operation, may be introduced through the steam line 3 to direct steam at the cutting. edge of the knife 3 1. During continuous operation, it is found not to be necessary to use th steam, but its use is found desirable when starting the formation of the sheet.

The moisture content of the sheet being removed from the roll may range from 12% to 30%, but we prefer to take off the glue when its moisture content is from 17% to 24%. A higher moisture than 30% causes the sheet to adhere to the conveyor, While a dryer sheet is not conducive to a consistent operation. The sheet thickness varies from ,4 inch to /32 inch, depending upon the chill roll speed used in operation.

The chill rolls are operated to provide a peripheral speed substantially less than the peripheral speed of the drying roll iii. Preferably, the ratio of the peripheral speed of the drying roll to that of a chilling roll is 2 /4 to 1 up to 2% to 1. Excellent results are obtained when the ratio is 2 /2 to 1. Such unequal speeds result in a doubling up of the film in the formation of the sheet, giving a rippled or crinkled effect.

The glue sheet 35 does not tend to adhere to the chromium-surfaced roller M, but does cling to the steel rollers 42, as indicated in Fig. 4, and the knife 43 is eifective in removing the glue and the inner frost coating thereof from the chilling roller 42.

The outside or dryer side of the glue sheet is allowed to rest against the girts 41 of th endless conveyor 45. Thus, the dry side of the glue, combined with the spaced girts 41, and the crinkled character of the glue sheet 36 itself, all cooperate in minimizing the tendency of the film 36 to stick to the conveyor. Uniform results can be obtained because the glue sheet 36 can remain plastic, containing a substantial amount of moisture, thus permitting a uniform sheet-forming and drying operation.

The glue is carried through the apron drier where it may be subjected to heat and air, and finally the sheet is drawn onto the outlet conveyor 52. Here, if the sheet is thick, it is subjected to a blast of room temperature air from fan 55 before being broken up by the wheel 53. The breaker 53 breaks the flakes into an average particle size of from one square inch to any desired size. The final moisture content is about 12% which is considered as commercial dry glue. From this point, the flakes can be ground in any regular mill to the degree desired by the user.

While in the foregoing specification, we have described the invention in considerable detail, both as to steps and apparatus, for the purpose of illustrating one embodiment of the invention,

it will be understood that such details may be varied widely by those skilled in the art without departing from the spirit of our invention.

We claim:

1. In apparatus for the film drying of glue, a frame, a drying roll rotatably mounted in said frame, means for heating said drying roll, means for supplying a film of glue to the roll, a scraper for removing the film as a sheet of glue from said drying roll, a pair of chilling rolls rotatably mounted in said frame, one of said chilling rolls having a surface to which said sheet does not adhere while the other of said chilling rolls has a surface to which the sheet tends to adhere, and power means having connections with said rolls for rotating said drying roll at a greater peripheral speed than the peripheral speed of said chilling rolls.

2. The apparatus of claim 1 in which one of the chilling rolls is chromium-surfaced while the other roll has a steel surface.

3. In a process for drying glue in sheet form, the steps of applying glue in a film upon a heated rotating roll, scraping the film away from the roll to form a sheet, and passing the sheet between two tension rolls while rotating the tension rolls at a slower peripheral speed than the heated roll whereby said sheet under said scraping action is crinkled as it leaves said roll.

4. In a process for drying glue in sheet form, the steps of applying glue in the form of a film to a heated rotating roll, scraping the roll to free the film when partially dried from said roll and to form a glue sheet, passing the sheet between chilled rollers, and rotating the drying roll at a peripheral speed greater than the speed of the chilled rolls whereby said sheet under said scraping action is crinkled as it leaves said roll.

5. In a process for drying glue in sheet form, the steps of applying glue to a heated rotating roller to form a film thereon, scraping the roll to free'the film when partially dried from said roll and to form a glue sheet, and passing the sheet between tension rolls at a slower peripheral speed than the heated roll; whereby said sheet under said scraping action is crinkled as it leaves said heated roll, said heated roll being rotated at a peripheral speed bearing ratio to the peripheral speed of the tension rolls of from 2 to 1 to 2% to 1.

ALBERT H. ZEIGLER. CHARLES M. HARRIS, JR.

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

UNITED STATES PATENTS Number Name Date 1,318,464 Schweizer Oct. 14, 1919 1,582,604 Hopkinson Apr. 27, 1926 1,583,484 Morrison May 4, 1926 1,746,751 Van Derhoef Feb. 11, 1930 2,140,788 Cowgill Dec. 20, 1938

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