US2571064A - Mounting for stencil screens - Google Patents

Description

Oct. 9, 1951 c. F. scHAi-:FER

MOUNTING FON STENCIL SCREENS Filed Nov. l, 1945 f gether.

Patented Oct. 9, 1951 UNITED STATES- PATENT OFFICE 2,571,064 Y MOUNTING FOR STENCIL SCREENS Charles F. Schaefer, Westport, Conn.

Application November 1, 1945, Serial No. 626,051

This invention relates to a coating and printving machine of the type in which there is a rotatinghollow drum carrying a stencil screen through wh1ch the coating material, such, for example, as an adhesive or ink, is forced from the inte- 'rior of the drumA to the paper, cardboard, or

other article, to which the coating material is to be applied, and has for an object to provide an improved type of mounting for the coating screen and one in which the stencil member is held in the proper position, but which, both before and after use, can be laid out flat so that it may be economically stored or transported, as in this condition it requires a minimum of space.

With the foregoing and other objects in view, I have devised the construction illustrated in the accompanying drawing forming a part of this specification. It is, however, to be understood the device is not limited to the specic details of construction and arrangement shown, but may emand the stencil sheet and mounting therefor are A greatly exaggerated. The device comprises a hollow rotary cylindrical drum 5, which may be of sheet metal closed at its opposite ends so as to provide a container for coating material, mounted at its opposite ends on suitable supporting rollers 6 which may be driven by any suitable means (not shown) to rotate the drum 5. Such means may, for example, be such as that shown in my prior patent for Stencil Coating Machine,

No. 2,382,920, issued August 14, 1945, and there lmay be a lower pressure rollerY 'I to support the work and hold it against the surface of the stencil during the coating operation and insure that kthe article being coated and the stencil move to- This may be mounted on yieldable .the roller against the drum. Supports or tables I and II may also be provided for the work .-12 at. vthe forward and rear sides ofthe drum 6 Claims. (Cl. 101-120) to guide the work into the coating position and receive it after it leaves this position, and the tables are mounted on means whereby they may be adjusted up and down or toward and from the drum to properly locate them for work of different thicknesses. Any suitable adjusting means may be employed, that shown being a hand nut I3 on a screw I4 and supported on any suitable support I5. Spring means may also be provided to yieldingly press the drum against the supporting rollers 6 to secure the proper traction and also prevent the drum being lifted from the rollers during the coating operation. In the drawing this is shown as a pair of rollers I6 engaging the top of the drum at the opposite ends thereof and mounted on a connecting support I1 pivoted at IB on a supporting arm I9 which is in turn pivoted at 2'0 on the frame 2| of the machine with a spring 22 pulling this lever downwardly to press the roller I6 against the drum. A set of these pressure rollers may be provided at each end of the drum beyond the stencil so as not to interfere with it. The springs 22 should be heavier than the springs 9 for the pressure roller so that these latter springs will not lift the drum from the driver rollers 6.

In one side of the drum is a large opening or window '23 over which is located the stencil 24 for applying the coating to the Work. This stenci] is mounted on a large flexible sheet 25 and cemented thereto over a large opening or window 26 in this sheet. The stencil is large enough to overlap the edges of the opening 26 in the exible sheet 25 on all sides, and the ilexible sheet 25 is of a width to overlap the window or opening 23 in the drum 5 on all sides. This flexible sheet, however, is preferably of a length to extend throughout the entire circumference of the interior of the drum, and may be`overlapped at its ends as indicated at 21 and these ends cemented together, or these ends may be abutting or even spaced from each other and cemented to the interior of the drum. In either case, the exible sheet 25 carrying the stencil 24 is securely mounted and held in the drum against movement or creeping during the coating ope'ration.

The stencil 24 could be mounted on the inner side of the exible sheet 25, but it is preferably mounted on the outside, as shown in Fig. 1, because this secures several material advantages. The stencil is preferably larger than the opening or window 23 in the drum so that it overlaps the edges of this opening, as shown at 28, and .also the opposite endsof the opening, because when it does this, pressure from the inside of the drum forcing the coating material through the stencil, does not then tend to separate the stencil from the supporting sheet or the drum, because 4the pressure holds it between the sheet and the drum. A very material advantage of having the flexible stencil mounted on the outside of the .flexible sheet 25 is that when the sheet is applied to the interior of the drum 5 and rolled up into the cylindrical shape, it automatically stretches -or forms the stencil into a true arc of a circle, Vso that there are no wrinkles or other parts out of position, and it definitely retains this shape.

The stencil element 24 may be of plain flexible porous material to permit passage of the coating material and form a uniform coating una `work of the size and shape of the window or. opening 26 in the flexible sheet 25, or a mask 29 could be applied to the stencil to block out certain portions of it so that the coating material would be .applied .ina desired design, or portionsofthe stencil itself couldbe blocked out by any suitable material, such, for example, as lacquer, to pre- .vent passage of .the coating materialat. certain portions of its surface to thusapplythe .coating in various designs.

The interior chamber of the drum 5. preferably forms a reservoir or container for a considerable .amount of the coating material indicatedat 3D,

.andas described in my prior patent abovenoted, .and located within this chamber and extending `longitudinallyof the drum and immersed inV this material is .a'suitable pressure device, such asa roller or other type of squeegee 3|, pressing .against the inner surface of the .flexible mounting sheet 25 and the stencil to force the coating .material through the stencil as it passes under .this pressure device, and thus apply the coating material to the Work l2 as it passes between the .drum and the pressure roller 1. The pressure Vdevice 3|.is yieldably vmounted in anysuitable manner, such, for. example, as by yieldable bear- .ings 32 for the supporting shaft or trunnions 33,

.and pressed against the drum by suitable ysprings 34,. Temperature control means for the coating material may be provided, as described in my prior patent above noted.

This construction and arrangement ,comprising the combination of. a flexible sheet 25 with the .window or opening vin it to be located over the window or opening in the drum 5, to which flexible sheet can be adhered a screen or other suitable stencil element, this combination of flexible screen or stencil to be inserted or` mounted in the hollow rotatable drum, as described, is of material advantage over the old structures. It may be used with any hollow type of drum used for printing and coating purposes, and in the present case the term coating is used inthe broad sense of either applying a coating toan extensive surface, either to merely cover the surface or provide an adhesive to -which otherarti- Vclesmay be applied, or to apply a coating such as adhesive in a given design, or as printing with ink or other materials of various colors, printing being in reality the application of certain coating material in given designs. It is preferred to use it as illustrated, with an amount of the coating material in the drum which forms a container for it, but other suitable feeding devices for supplying the material to the stencil and forcing it therethrough may be used, the principal im- -provement being the mounting of the flexible VVVscreen or stencil on the flexible supporting sheet, und then mounting thiscombination on the in-v fside of the rotatable'drum. There are numerous 4 advantages secured by this. It permits the ready insertion, removal and storage and re-use of this screen or stencil, and by placing it on the inside of the drum the difliculty of confining the solution in the drum when the screen is mounted or wrapped on the outside of the drum is overcome because with this arrangement the pressure from the inside of the drum merely presses the screen against the walls of the drum, while if the screen were wrapped on the outside of the drum, as is .the old and common method of mounting it, the pressure tends to force the screen away from the drum, permitting the coating material to flow .out around the edges between the drurri and the screen. After the coating operation the flexible mounting .Sheet 25 with the stencil screen can be removed from the drum and laid flat, for conlvenient, economical and safe storage, in condition to be readily used again when desired. In this condition it requires a minimum of space in storage.. ..'I.he. stencil screen can be of flexible cloth. or.v metal or. other; suitable. porous ,material `through which .the liquid or semi-liquidcoating material may pass to the surface to Vbe coated. The flexible mounting or supporting .sheet 25 can be ofv any suitable flexible sheet material, such, for example, as metal, rubber, plastic, .wire screen, fabric, cardboard, paper, fiber, or anything strong enough to hold together and support the stencil. In mounting it in the drumit caribe either cemented to the drum or heldby Suitable .clamping means within the drum, as desired. As suggested, for different designs a mask can be placed over the stencil screen, as indicated at129, to block off parts of the screen for various `designs, or a design could be cut in the mask,..or parts of the screen itself could be blockedV off to prevent passage of the material. and make 'the design. .If the supporting flexible sheet`25 were made of metal screen or some porous material, the part thereof within the window or opening`23 of the drum could itself form the stencil screen, and parts could be blocked out b y `some'thlck solution or` cement, so the coating solution will be forced only through openings of the design or the stencil sheet.

-Having thus set forth the nature of my invention, what I claim is:

1, In a machine of the character described, a hollow rotatable drum provided with a relatively large opening in its side wall, a flexible sheet supportlarger than saidiirst opening and itself provided with a relatively large opening in alignment with the opening in the drum, ailexible porous material adapted for lpassage of a coatingmaterial secured to said flexible sheet over theopen- Aing therein, said flexible sheet being mounted at the inner side of the side wall of the drum and located with the porous'material over the opening in the drum, the porous material being larger than the opening in the flexible sheet so as to overlap opposite edges of said opening, and pressure means within the drum for forcing a coating material `through the'porous material to an article outside the drum.

2. A stencil coating machine of the character described comprising a hollow rotatable drum provided with a window in its side wall, theinterior chamber of said drum forming a container for a quantity of semiliquid coating solutlon,ra flexible supporting sheet mountedv on the inside of the drum over said window. and extending on .the inner surface of the closed side wall of the drum beyond the sides/of the window, said sheet being provided .with a relatively largeopeningjn 'valignment :with .the -windows'. :a .flexible percus` e stencil mounted on and secured to the flexible sheet over said opening, said stencil being larger than the opening in the supporting sheet so as to overlap opposite edges thereof, p-ressure means within the chamber in the drum extending longitudinally thereof and immersed in the solution in the lower part of the drum to force the solution through the stencil as the drum rotates, means for rotating the drum, and means for retaining the article to be coated against the outer surface of the drum.

3. In a stencil coating machine of the character described, a hollow rotatable drum provided with a window in its side wall, a exible supporting sheet provided with a relatively large opening therein mounted on the inner side of the closed side wall of the drum so as to conform to the curvature thereof and arranged with its opening in alignment with the window in the drum, a exible stencil mounted on the outer curved surface of said flexible support over the opening therein and overlapping the edges of the window in the drum between the said support and the inner surface of the drum, pressure means within the drum extending longitudinally thereof and engaging the inner surface of said sheet and stencil to force coating solution through the stencil as the drum is rotated, means for rotating the drum, and means for retaining the article to be coated against the outer surface of the drum.

4. In a stencil coating machine of the character described, a hollow rotatable drum provided with a window in its side wall, a flexible supporting sheet mounted on the inside of the side wall of the drum over said window so as to conform to the curvature of the drum, said sheet being provided with a relatively large opening in alignment with the window, a exible stencil mounted on the outer curved surface of said supporting sheet over the opening therein and larger than said window so as to overlap opposite side edges of the window between the supporting sheet and the inner surface of the drum, the interior chamber of said drum forming a container for a quantity of semiliquid coating solution, pressure means within the chamber in the drum extending 1ongitudinally thereof and immersed in the solution in the lower part of the drum to force the solution through the stencil as the drum rotates, means for rotating the drum, and means for retaining the article to be coated against the outer surface of the drum.

5. A stencil coating machine of the character described comprising a hollow rotatable drum provided with a window opening in its side Wall, a exible supporting sheet provided with a relatively large opening therein mounted on the inner side of the curved side wall of the drum so as to conform to the curvature thereof and extend beyond the edges of the window opening, said sheet being arranged with its opening in alignment wtih the window opening in the drum, a flexible stencil mounted on the supporting sheet over the opening therein and larger than this opening so as to overlap the supporting sheet around this opening and secured to this sheet, pressure means within the drum extending longitudinally thereof at the inner surface of said sheet and stencil to force coating solution through the stencil as the drum is rotated, means for rotating the drum, and means for retaining the article to be coated against the outer surface of the drum.

6. A stencil coating machine of the character described comprising a hollow rotatable drum provided with a window opening in its side wall, a flexible supporting sheet provided with a relatively large opening therein mounted on the inner side of the curved side wall of the drum so as to conform to the curvature thereof and extend beyond the edges of the window opening, said sheet being arranged with its opening in alignment with the Window opening in the drum, said flexible sheet extending throughout the entire circumference of the interior of the drum, a exible stencil mounted on the supporting sheet over the opening therein, said stencil being larger than this opening so as to overlap the sheet about the opening and secured thereto, means within the drum at the inner surface of the exible sheet and stencil to force coating solution through the stencil as the drum is rotated, means for rotating the drum, and means for retaining the article to be coated against the outer surface of the drum.

CHARLES F. SCHAEFER.

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

UNITED STATES PATENTS Number Name Date 513,212 Stackhouse Jan. 23, 1894 553,805 Deckert Jan. 28, 1896 2,191,134 Playford Feb. 20, 1940 2,419,695 Shuttleworth Apr. 29, 1947

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