US1672403A - Apparatus for casting composition sheets - Google Patents

Description

June 5, 1928. 1,672,403

' E. R. ARMSTRONG APPARATUS FOR CASTING COMPOSITION SHEETS Filed Oct. 14, 1924 2 Sheets-Sheet Bylzz sAttorzzey WWW/M17,

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o v o O O O O O O 18 Inventor: ER. flrmsfr'ong,

June 5, 1928;

v 1,672,403 E. R. ARMSTRONG APPARATUS FOR CASTING COMPOSITION SHEETS I 2 Sheets-Shet 2 Filed Oct. 14, 1924 Inventor 7 15 R. Akmsfrony 11 Bylaw/Niamey.

Y Patented June 5, 1928.

1 UNITED STATES PATENT OFFICE.

' EDWARD R. ARMsrRoNe, E HoLLYoAx, DELAWARE, ASSIGNOR TO E. I. DU Pom: DE

NEMOURS & COMPANY, OF'WILMINGTON, DELAWARE, A CORPORATION or ELA- CID WARE.

APPARATUS FOR CASTING COMPOSITION SHEETS.

Application ma October 14, 1924. Serial m. 743,590. 7

This invention relates to machines I and methods for making sheets of material such as cellulose ester compositions, for example,

celluloid and pyralin, by depositing a solution of the base. material, for example, pyroxylin, upon a proper surface and then removing the solvents. Such a procedure I conveniently term .casting.' In particular,

7 the invention relates to machines for making such'asheet-continuously and .of any desired width and thickness, especially a relatively heavy sheet suitable for use in the.

arts in which cellulose ester plastics, made by making blocks and then sheeting the blocks, are applied, as for automobile windows, brush backs, and so on; and also re lates to the making of striated sheets.

It has heretofore been the practice, in

making stock for narrow, very thin strips,

as photographic films, to cast the solution on wheels or drums, and this was feasible, for narrow, thin strips, as the relatively Wide cast sheet could be cut longitudinally to provide several strips, giving a fairly high production in film feet. When, however, it becomes a question of making widethick cast sheets, the casting-on-a-wheel method at once fails for-practical purposes; not only is the wheel, for practical reasons, of necessity of limited width but, particularly, the solution deposithaving to be large, per unit of wheel area, in order to give the desired thickness, which entails the removal of large amounts of solvent before the fresh film can be successfully stripped, the wheel movement must be excessively slow, giving an impossibly low production. The apparent alternative is to use a larger wheel, but this is plainly impractical: for example, a wheel to provide a circumferential distance from casting hopper to strippingpoint of about 350 feet-a distance frequently desirable to use to' give high production-would be about 112 feet in diameter which is plain ly a grossly impracticable size.

Seeking to solve the problem thus presented, I turned to a casting machine of the belt type, that is, a machine whose casting surface should be a belt, it being evident that a belt machine, theoretically, could have a casting surface as long as desired. I found that a belt made up of a large number of plate sections jointed together to give face. I have, however, solved the problem:

I have devised'a belt-type casting machine having an unjointed, flexible, continuous belt of long span and sufficient strength, with a smooth continuous casting surface. It is a major object of. the invention to provide such a machine' It is also an object to provide a machine of the general character indicated by which striated sheets can be made; and it is a further object topro vide a method, conveniently practiced with the aid of said machine, for making striated sheets. To these ends, and alsoto improve generally upon casting machinesv and methods, the invention consists in the various matters hereinafter described and claimed.

I am aware of abstract suggestions of continuous-belt casting made, evidently, by those who had not solved the problem of actually producing a casting machine embodying any such belt, this being evident from the fact that, as will appear hereinafter from the considerations set forth, the ab-- stract suggestions of such a machine are by no means a solution of the problem since such solution primarily involves and presents the problem of actually providing a proper belt; this major consideration has been wholly passed over and ignored.

WVitho'ut restricting the invention thereto, the same is described with more particular reference to the embodiment illustrated in the accompanying drawings, in which Figure 1 is a simplified sectional side elevation of the casting machine;-

Figure 2 is a. cross-sectional view substantially on the line 2-2 of Figure 1;

Figure 3 is a fragmental face view of the casting belt;

Figure 4 is a longitudinal section of the expansion device of the enclosure of the machine;

Figure 5 is an end view of the said expansion device;

Figure 6 is a side view of the shlftable take-up bearing of the machine;

Figure 7 is a fragmental section showing a structure for mounting the enclosure upon a bearing for a belt Wheel.

Figure 8 is a vertical cross-sectional view of the casting hopper;

Figure 9 is a top plan view of the hop- P Figure 10 is an enlarged fragmental vertical cross-sectionalfview of the lower portion of the hopper; and

Figure 11 is an enlarged fragmental bottom view of a group of the blades of the solution-dividing means of the hopper.

Referring now to the drawings and more particularly to Figure 1, the machine comprises a casting belt 1 carried by the belt pulleys or wheels 2, 3 and full enclosed substantially air tight by the casing 4 having the air outlet 5 and the air-intake fan 6. A solution trough 7 is carried by the casing 1 in position to discharge a sheet of solution across the width of the belt 1, such trough being desirably of the type here illustrated (Figures 8 to 11) which provides for the making of striated sheets, for example factitious ivory, by the casting method. A stripping roll 8 extending across the width of the sheet S of cast material, for example, pyroxylin, is mounted in position to receive the sheet and pass it to drying equipment (not shown). The belt is caused to travel by power applied to the driving pulley 2 on the shaft 2 of the wheel 2. In operation, the (pyroxylin) solution P is continuously deposited on belt 1 and as the belt travels its circuit (clockwise in the drawing) the solvents are partially removed, leaving the sheet S. The belt speed and solvent recovery rate are such that by the time any given portion of the sheet S has reached the roller 8, it is in condition tobe stripped off in a self-sustaining continuous length. Such solvent recovery app'aratus,.and so on, may be used as desired, the present invention not being primarily concerned with such features. It is to be particularly noted, however, that in order that the deposit may have its solvent removed sufficiently slowly to give a proper and usable sheet it is advisable, with present day solvent recovery apparatus and so on, that the belt have a length of at least about feet, with the spans about 30 feet; which indicates the necessity for a belt of considerable thickness to give the necessary strength.

In particular accordance with the present invention the belt is a single continuous band of metal, highly polished and smooth. In my U. S. application entitled Plating apparatus and product thereof, filed October 14, 1924, Serial No. 743,589, Armstrong Case 1, I have disclosed a machine, and a specimen procedure for operating the same, whereby such a band of indefinite length, any desired width, and-this is a most important point-of sufficient thickness and of such good quality as to give the necessary strength, can be produced. Briefly, the belt is made by electrolytic deposition or plating of a metal, preferably nickel, upon a cylindrical cathode, from which the deposited metal is stripped in a continuous band, the machine having provisions for continuous operation, circulation of the bath, elimination of foam, constant brushing or clearing of the surface of the cathode and deposit, filtering of the circulating bath solution, and slow speed movement of the plating surface.' The nickel belt produced has a thickness of .01 inch to .05 inch, or greater if desired, and desirably .035 inch, a tensile strength between seventy and'eighty thousand pounds per square inch, and, as produced for the present machine a width of about two feet four inches and a length of abouteighty feet. To close the strip into a belt (see Figure 3) the abutting ends are dovetailed crosswise of the belt as at 1 and the joint silver brazed, an under strap 1 and rivets 1 being used if desired. WVhile in the figure the joint line and rivets are shown, it is to be understood that, actually, the finishing and polishing are. such that these points are practically invisible and the surface without inequality or flaw. The belt, and joint, are highly polished in the usual ways of the nickel polishing art.

As to certain of the details of the illustrated machine :The casing 4 is desirably of metal plates suitably held by suitable framing as will be understood by those skilled in the structural arts, such casingv comprising the upper and lower reaches 9 and 10 and the drum-like ends 11 and 12 with which the reaches are tangentially connected. If desired, rollers 13 for'supporting the belt may be provided in the casing. As indicated in Figure 2, wherein the lower reach is shown of less cross section than the upper, the casing enlarges oppositely to the direction of travel of the belt providing for a decrease in the velocity of the air current as it reaches the successive points of increasing amounts of solventsto be removed.

The heads of the drums 11 and 12 may be connected about bearings, as 14 and 15 at each side of each drum, in any desired manner. As here shown, Figure 7 the hearing,

as 15, supports, at 16, a collar 17 through whch the shaft 18 of the wheel passes, and this collar has the wall or head 12 of the drum fastened thereto. In this way the casing is held air tight upon the shaft.

It is highly desirable that, particularly along its upper span, where the solution is more fluid and therefore more. liable to flow or shift to conform to any waves or nonlevelness of the belt, the belt be held under suffic ent tension to keep it flat; but as the belt is of metal it will contract and expand due to temperature changes. The present structure has provisions for maintaining the belt flat. As here shown, there are pro-' .vided equalizing structures 19, 19", one in each reach of thecasing and the like bearings, as 15, one at each end of shaft 18"of the wheel'3 are urged in a, direction to carrythe wheel 3 away from the wheel 2, the ex-' supports the shaft 18, this hearing being mounted upon the-slideway block 21 (suit-. ably stationarily mounted upon supportsrising from the floor) for movement to and 1 fro thereon in the longitudinal direction of the belt 1, the bear'ng and block havin cooperative slideways and tracks 20 an 21 as indicated. For urging the bearing'20 in the direction to take up slackness in the belt, there is provided the expanding spring '22 having one end received in thesocket23 otthe bearing member 20 an d the other abutting the abutment1block24. The block 24 is adjustable to change the force of the spring,.it being shown as forming the end of a screw 25 threaded through the projection 26 from the stationaryslideway block. The screw carries a handle 27 for turning the same, and a lock nut 28. WVith this construction the bearings 15 which carry the wheel 3 are urged away from the wheel 2, with a force :that canbe regulated as desired by adjustment of the screw 25. It will be understood that'the springs are adjusted to such' tension as to permit retreat of the bearings 15 upon contraction of the belt.

The illustrated expansion devices, heretofore designated generally as 19, for permitting changes in the length of the casing as the wheel 3- shifts, carrying themdruni casing 12 with it, are as follows, see Figures 4 and 5. Each expansion device is made i up of four corrugated sheets, as 19", of

metal, one for-each side. These are mitered and brazed or soldered together at the corners as indicated at 29, making a box-lke structure open at the ends. structure .19 is carried by a rectangular frame, as 30, abutting a mating-frarne 31, the metal sheets of the casing'proper 4 and of the structure 19 being out-turned and held between the frames as shown. While various materials and detailed dimensions for the structure 19 may be used, I have found that, in a structure having its inside crosswise dimensions 2 feet 4 inches by 5% inches, and about 1 foot long, copper sheets .0375 inch thick and having 5 corrugations at about 30 angles and about 2 inches deep are satisfactory as readily providing for such movement as is called for in taking care of about an eighty-foot belt-of nickel.

The solution trough, heretofore designated generally as 7 is, in preferable accordance block across the grain.

At'each end the ter to provide for the casting of a striated sheet, as factitious ivory. Such striated sheets have heretofore been made by the tedious process of making sheets of the individual colors, pressing thesheets (laid alternately) into a block, and sheeting the With the present device the sheets can be originally made in striated form. The trough 7 compr ses the general hopperbod 32 made up of the end walls 32"., 32. and side Walls 32, 32" suitably fastened to the end walls, the side walls, at

the terminations of their inclines 32, 32"

being spaced to provide the discharge slot 33 extending longitudinally across the bottom of thehopper body. Thehopper body is divided lengthwise by the wall 34"forming separate solution chambers 35", 35. At. the base of the wall is provided structure, designated generally as 36, whereby the solutions P and P, flowing from the hopper chambers, are caused to meet and joinin streams. These streams as they are cast on the casting surface, (belt 1) give a sheet S with the deposits from the solutions joined in striae running longitudinally of the sheet. For in-v stance, if solution P 'be taken as white and solution P as cream, there will be produced striated goods having the appearance of ivory.

The structure 36 comprises a series, longi-. tudinally of the hopper, of flow separators 36.- Conveniently the wall 34. and structure 36 are integral and desirably as illustrated. Here, the wall 34 is made up of a series of blades or units each presenting a pointed portion 36, and held in position centrally the blades with immediately adjacent blades facing in opposite directions, that is, with alternate blades facing in the same direction. This provides a structure which maintains the separationof the solutions until the outlet 33 is substantially reached and yet discharges the solutions in longitudinally contacting streams, each stream from a given chamber of the hopper running down between the side of the hopper and the edge 33 of the blade which separates into streams the flow from the other chamber. While various specific dimensions for the points of the blades may be used, I have found that a distance between thepoints, crosswise the hopper discharge slot, of .03 inch, whereof each individual solution outlet, with blades about .03 inch thick, will be about .03 X .03,

satisfactory. With a hopper about 1 foot long about 37 5 blades or sheets are thus required. Evidently, upon the widths of the blades will depend the widths of the striae, so these may be made as desired by using particular blades, of the same or different widths, or by facing several immediately succeeding blades in the same direction, and so on. Control of the amount of solution discharged from a chamber per unit of time and of relative amounts discharged, may be provided for in any desired manner. As here shown, control is provided by controllingthe head of the solution. Thus, in Figure 8 separate solution inflow pipes 38 and 38 and overflow pipes 39 and 39 are provided, the overflow pipes of course determining the heads of the solutions. By way of example merely, the pipe 39 is placed higher than the pipe .39, giving a greater head, and consequently a greater flow, to the solution in the compartment 35 The solu tions used may be of the kinds usual in the art and containing the base material, for example pyroxylin, suitable solvents, and pigment.

For example, there may be used in making factitious ivory :a white solution, comprising nitro-cotton 26, calnphor 8, zinc oxide 3, ethyl alcohol 6, acetone 57 (parts by weight), and a cream solution like the white except that somewhat less zinc oxide is used, say 2.5 parts, whereby the yellowish natural color of the unpigmented solution is not fully obscured. It will of coure be understood that any combination of colors desired may be used, and the desirable viscosity of the solutions under any particular circumstances will be quickly arrived at by those skilled in the art. Although particular reference has been made to a double-flow hopper it will beunderstood that a single-flow hopper can be used if it be desired-to produce merely a plain sheet. The removal of the solvents, solution deposits per unit of area, and like well understood factors, present no new problems and with them the present invention is not primarily concerned, the usual practices of the .art being satisfactory.

I claim:

1. A machine for casting solutions into sheets comprising a belt-line casting surface member, such member being a continuous sheet entirely of electrolytically deposited nickel having a thickness of at least substantially .01 inch.

2. A machine for casting solutions into sheets comprising a belt-like casting surface member, such member being a continuous sheet entirely of electrolytically deposited nickel and having a thickness substantially between .01 and .05 inch and a tensile strength substantially between and 80 thousand pounds per square inch.

3. A machine for casting solutions into supporting means to shift therewith, and

provlsions associated with said structure providing for the shifting of said portion with said supporting means without disruption of said structure.

5. In a machine of the character indicated, in combination, a closed belt, means supporting the belt, such means being shiftable to maintain the belt taut, an essentially rigid structure enclosing the belt, such structure having a portion connected with said supporting means to shift therewith, and provisions associated with said structure providing for the shifting of said portion with said supporting means without disruption of said structure, said structure comprising upper afid lower tunnel-like reaches enclosing the belt, and said provisions comprising expansion-and-contraction sections inserted in said reaches.

6. In a machine for casting a solution into a sheet, in combination, a closed metal belt presenting the casting surface, a pair of belt wheels for supporting the belt and encompassed within the spans of the belt, an essentially rigid enclosing structure for the belt and wheels, shiftable bearings for one of said wheels, a portion of said structure being connected with said bearings to shift therewith, and means associated with said structure providing for the shifting of said portion with said bearing without disruption of said structure.

7. In a machine for casting solutions into a striated sheet, in combination, a casting surface device having a casting surface of a width to receive a plurality of simultaneously deposited solution streams thereon,.

side by side, and a device for depositing said streams in merging relation, one of said devices being movable relatively to the other whereby said deposits shall extend along said casting surface, said depositing device comprising a receptacle divided into solution chambers, and means adjacent the bottom of the receptacle for dividing the several flows into streams and interspersing the streams from the several flows, such dividing means comprising a bank of non-registering blades with certain blades extending to one side of the hopper and spaced from the other side and other blades reversely arranged.

In testimony whereof I aflix mvsignature.

EDWARD R. ARMSTRONG.

CERTIFICATE OF CoRRECTIoN.

Patent N0. 1,672,403. Granted June 5, 1928, w

EDWARD R. ARMSTRONG.

It is hereby certified that error appears in the printed specification of the .above numbered patent requiring correction as follows: Page 4, line 35, for

the misspelled word "coure" read "course"; same page, lines 52 and 66, Claims 1 and 3, for the compound word "belt-line" read "belt-like"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the Case in the Patent Office.

Signed and sealed this 3rd day of July, A. D. 1928. I

I M. J. Moore, (Seal) Acting Commissioner of Patents.

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