US1614609A - Process of and apparatus for making stencil sheets - Google Patents

Description

Jan. 18 1927. 1,614,609

v J. D. GRANGE ET AL PROCESS OF AND APPARATUS FOR MAKING STENCIL SHEETS Filed Dec. 30. 22 2 Shets-Sheet 1 L I M Q a m I7ZU77757".5 Jo/ml]. Grange Edward F [fosj/lra 0 YMW 7w Jan. 18 1927. 1,614,609

J. D. GRANGE ET AL PROCESS OF AND APPARATUS FOR MAKING STENCIL SHEETS fiver 1W3 Joh n D. Grange Edward]? Vps'ylra Patented Jan. 18, 1927.

UITED' STATES HP'ATENT OFFICE.

JOHN DOUGLASS GRANGE, OF BROOKFIELD, AND EDWARD FRANK.VOSYKA, OE CHI- CAGO, ILLINOIS. ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCORIORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF AND APPARATUS FOR MAKING STENCIL SHEETS.

Application filed December 30, 1922. Serial No. 610,053.

This invention relates to means for and methods of making stencil blanks of the type described in the co-pending application of John Douglass Grange, Serial No. 603,125, filed-Nov. 24, 1922. U

Stencil blanks of this general type are made by impregnating sheets of thin, open,

lace-like paper such as Japanese Yoshino paper or the like with a protein impregnating compound.

Heretofore it has been the practice in making stencil blanks to place the base sheet upon the surface of an impregnating bath, maintaining it in such a position until it is thoroughly impregnated with the mixture and then withdrawing it in such a manner that any surplus solution is removed and returned to the bath, the impregnated blank was then exposed to the light and allowed to dry.

It has been found that blanks produced )y this process are not always uniform and are expensive to manufacture. culty encountered is due to the imperfect contact between the tissue sheet and the surface of the liquid caused by the air or gas bubbles formed in the liquid by the return of the .surplus fluid to the bath. Another difficulty which has been experienced is due to the cooling of the surface of the impregnating bath and of the'tissue sheet when in contact with such surface thereby-congeal ing the solution too quickly on the sheet.

Some stencil blanks of the character-used prior to the invention described in the above mentioned co-pending application must be subjected to light for a considerable period of timewhile drying, while with the stencil blanks as described therein it is not necessary to expose the sheets to the light, Thus it is possible to place them in a drying chamber immediately upontheir removal from the impregnating solution. In this way the drying of the sheets may be. materially hastened.

Objects of the invention are to improve the quality and to cheapen and expedite the manufacture of stencil blanks of the impregnated type. p

Another objgct of the lnvention is to pre- 1 vent the intro uctio-n into a body of liquid of air or gas bubbles present in a source of supply.

In order to secure these objects in accordcosity of the solution and the excess solution is removed immediately upon the withdrawal of the blanks from the bathand any bubbles which may be formed by the removal are dissipated during the'return of the excess solution to the bath, so that they do not appear upon the surface thereof. In this manner. uniform contact of the tissue with the solution is insured. The blanks are then supported in conveniently arranged frames which are placed in a drying oven or chamber. When' completely dried a plurality of the frames may be placed upon a suitable support and the stencils removed by cutting or otherwise.

These and other features of the invention will appear from the following specification and the accompanying drawings, of which:

Fig. 1 shows the general arrangement of the apparatus;

Fig. 2 is a plan of the section of the impregnating unit;

Fig. 3 is a fragmentary end view in section of such unit; K Fig. 4 is an enlarged view also in section of a portion of Fig. 3, and

Fi 5 shows a side view in cross section of the receptacle containing impregnating solution as well as an impregnating blank which is being withdrawn.

An impregnating unit designated generally by the character A is placed upon a suitable table which may be provided withcastors or wheels for permitting its movement on the floor, as shown, or over a track or runway, in'proximity to a drying chamber or oven B. The impregnating unit contains character described in the above mentioned co-pending application. A door 20 is pro- .vided in the side of the unit to permit access to the tray 10 for pouring impregnating solution into the tray, while a door 21 is provided for giving access to a tank 22 within which an extra supply of solution is kept.

Underneath the tank 22 is placed an electrical heating element 23 of any suitable type, which may beconnected in any well known manner with a source of current for controlling the temperature of the solution so that the compound is maintained at the desired viscosity. Below the element 23 a compartment is provided within which a workin supply of sheets of tissue 25 may be kept. ilnderneath the receptacle 10 another electrical heating element 26 is provided for maintaining the working supply of the impregnating solution at a desired tempera ture.

It will be noted that the element 26 extends beyond the sides of the tray 10, and that metal shields 27 extending upwardly on the edge 'of the element turn inwardly and downwardly fromthe sides and the reare end of the tray in such a way that currents of heated air produced by heating element 26 are directed to the surface of the solution thus insuring that such sur face is maintained at substantially the same temperature and viscosity as the other portions of the bath. Since in drawing the tissue sheet across the surface the rear end of the sheet may not immediatelycont-act with the surface it is especially important that the surface be properly heated at this point. At the outer end of the tray 10, a scraper 28 preferably of wirev is provided, one end of which is suitably anchored by means of solder or arivet and the other end of which is provided with a thumb screw 29 or other means for maintainin the wire taut. This wire 28 is provided or removing the surlus solution from the stencil blank 30 as It is being withdrawn from the tray 10.

Such surplus solution drops into a receiver 31 formed b the ends of the tray and wall 32. A plura it of openings 33 of very small size ar'e provi ed in the lower end of such wall for the interchange of the solution in the two compartments of the tray.

The wall 32 having the restricted openinis 33 provides what may be called a bu ble dam. If this meansf'were not provided as the surplus solution flows into the working supply of solution any air or gas bubbles formed by the removal of the surplus solution from the blank or the dropping of such solution into the receiver 31 would rise to the surfaceof the solution and mi ht prevent contact between the'solution an sheets of. tissue subsequently placed in the bath.

The impre nating unit A is also provided with a suitable exhaust pipe 40 through which the fumes which may be formed by the impregnating solution. will be carried away by means of a power driven fan or otherwise. An ordinary incandescent lamp 41 connected with any suitable source of electr cal current is provided for properly illuminating the interior of the unit, and

a. glass plate 42 placed at a convenient angle allows the proper observation of tho impregnating process.

A suitable frame 43 which may be of wood and arranged for the reception. of a plurality of impregnated stencil blanks 30, is further adapted for insertion in a post formed at the-side of the impregnating unit A. The placing of the frame in a convenient position for receiving the blanks as they are taken from the impregnating bath has been found to be very useful. A triangular block 45 attached to the side of the unit A is provided-with a. vertical slot 46, in the front end thereof for the reception of the end post 47 of the frame 43: A button 49 is pivot-ed in any suitable manner by means of a pin 50 or otherwise on the block 45. The portion 51 of the button extending over the slot 46 is preferably made of greater length than the remaining portion so that when normally the greater weight of portion 51 causes the button to assume a vertical position, when the post 47 of the frame 43 is placed in the slot 46, the button is turned until the portion 51 of the button extends across the slot and rests upon the upper surface of the lower horizontal member of the frame. 'The button is held in this position by gravity securely locking the frame in the block 45. When it is desired to remove the frame it is simply .lifted, swinging the portion 51 of the button upby the heating pipes which may contain steam or water or suitable heating means. An exhaust pipe 71 provides for the taking away of the moisture andinsures the proper circulation of air within the chamber while the drying process is proceeding. A series of horizontal members 72 are provided upon "which the frames 43 are placed in vertical position when removed from the impregnating unit A. Sliding doors 73 are provided in the slide of the drying oven to permit ready access to the interior thereof.

A'movable carriage 75 is provided which travels upon suitable tracks 76 by means of rollers 77, such carriage being provided with vertical supports 78 against which the frames 43 may be placed upon their removal from the chamber, and a horizontal portion 79 for carrying a receptacle .or tray 80 in which the completed stencil blanks.

are placed upon their removal from the" The remaining compound is kept in thetank 22'and is also maintained at approximately the'same temperature.-

Theoperator grasps a sheet of tissue in the supply 25 by its corners, draws it over the surface of'the impregnating bathin the tray 10, and thereafter over the scraper 28, which removes the excess-solution from the sheet. It has been found that it is not necessary to keep the sheet in the bath for any longer period of time than that which is occupied by the drawing of the sheet over the surface.

The coated sheet is then placed on the frame 43 and attached by means of the compound to the upper and lower horizontal members of such frame. After the frame 43 is filled with blanks, the frame is removed the chamber B from its support at the side of the impregnating unit and is placed vertically upon the horizontal bars 7 2 of the drying chamber B. Another frame is then placed in proper position at the side of the impregnating unit A for the reception of additional coated blanks. It has been ,found desirable to coat the frames witha mixture of equal parts of paraflin and beeswax to insure the'proper attaching of the impregnating blank thereto.

It will be noted that the. unit A may be: readily moved along the side of the drying chamber B and that the sliding doors 73 of rovide access to the chamber at any point. n this manner the operator may start with the unit A at one end of the chamber B, place the frames 43 in that end of the chamber and move the unit A toward the opposite end as the chamber becomes filled with the frames. When the stencil blanks become thoroughly dried several of the frames L3 may be removed and laced in the roper manner on the carriage 5. The

blan s may be readily removed from several frames simultaneously by. cutting along the lower edge of the upper horizontal members and along the upper edge of the lower horizontal members of the several frames. The empty frames are then placed'in the chamber B for future use, it being unnecessary to remove the marginal portions attached to the upper and lower horizontal members each time the frames aroused, since the freshly impregnated sheets will readily adhere to such portions. These marginal portions may be removed at the convenience of the operator.

- The finished blanks as they are removed from the frames are deposited in the tray 80, from which they may be; removed and attached to suitable manila paper backing sheets preparatory to being stencilized.

By following this process and employing the structuresshown in the disclosed embodiment of the invention the manufacture. of stencil blanks is materially hastened and cheapened and a uniform product is assured. It has been found that if the interior of the drying chamber is maintained at a temperature of approximately 95 Fahrenheit and tion of the 9.11 within the chamber this period may be greatly reduced. However, stencils heretofore proposed wherein the coagulation of the impregnating compound is dependent upon exposure to light cannot be made in less than sixhours and under unfavorable light conditions may require twelve hours for their completion.

lVhat is claimed is:

1. In an impregnating device. a tray for holding impregnating compound,'a scraper associated with the tray for removing the surplus compound'from the article treated, a receiver for the surplus compound and a restricted connection between the receiver and the tray. for dissipating bubbles in the surplus compound.

2. In an impregnating machine, a receptacle for holding impregnating. compound 1 in such manner that an article may be rest- 7 ed en the surface of'the compound, and means for supplying a current of heated air to the article while resting on the surface of the compound.

3. In an impregnatin machine, an open receptacle for holding lmpregnatin compound in such manner that anartic e may be rested on the surface of the compound, means for supplying a current of heated air to the article while resting on the surface of the compound, and means for heating the compound in the receptacle.

4-. In an impregnating machine, an open receptacle for holding impregnating compound, and common means for heating separately the plying heat directed to the upper surface thereof.

body of the compound and sup- 5. In an impregnating machine, an open 6. In an impregnating machine, an open receptacle, for holding impregnatlng com pound, a heating element for heating the compound, and means for directing heated currents of air from the element to the surface of the compound.

7. In a'receptacle for liquids,

auxil ary portion and having a restricted opening to permit interchange of liquid bea wall diriding the receptacle into amain and an which comprises maintaining a compound sheet, attaching the sheet to a support, placing the supported sheet in a drying chamber, subjecting the supported sheet to a con stant temperature and removing the dried stencil blank from the oven.

9. In an impregnating machine, an open receptacle for holding an impregnating compound, a member dividing said receptacle into a main and an auxiliary portion having an aperture connecting the two portions whereby compound in the auxiliary portion may be returned to the main portion without disturbing the surface of the com pound contained therein, and means mounted. over the auxiliary portion and offset from said member for'returning to said auxiliary portion excess compound removed from the impregnated article.

In witness whereof, we hereunto subscribe our names this 20 day of December A. 1)., 1922.

JOHN DOUGLASS GRANGE. EDWARD FRANK VOSYKA.

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