US2511511A - Rotary screen printing machine - Google Patents

Description

June 13, 1950 A. J. MURPHY ROTARY SCREEN PRINTING means 3 Sheets-Sheet 1 Filed April 11, 1947 INVENTOR Y. H W P R U n June 13, 1950 A. J. MURPHY ROTARY SCREEN PRINTING MACHINE 3 Sheets-Sheet 2 Filed April 11, 1947 g m m x- I 3 m N% l a Q. & NM Q g E QR m I, R N\ L Q\ ATI'ORNEY June 13, 1950 A. J. MURPHY ROTARY SCREEN PRINTING MACHINE 3 Sheets-Sheet 3 Filed April 11, 1947 PM... June 13, 1950 ROTARY SCREEN PRm'nNi; MACHINE Arthur J. Murphy, New York, N. Y., assignor of one-half to S. Lawrence Atkins, New York, N. Y.

Application April 11, 1947, Serial No. 740,753 7 Claims. (Cl. 101-120) This invention relates generally to the art of painting or printing machines of the type in which a screen has permeable and impermeable areas disposed to form a pattern through which ink or coloring material may be applied through the screen on to the sheet material such as textile material, paper, leather goods, glass, plastics, wood, etc.

More specifically, the invention comprises a novel silk screen rotary painting or printing machine an important feature of which is the mechanical construction which enables the silk screen and supporting drum to rotate, while maintaining stationary the ink or color feedin elements within the rotating drum.

The following is a more detailed description of the invention, in conjunction with drawings, wherein:

Fig. 1 is a side elevation view through a silk screen rotary printing machine embodying the invention;

Fig. 2 is a sectional view through 2-2 of Fig. 1;

Fig. 3 is an end view of Fig. 2 taken along the lines 3-3;

Fig. 4 is a sectional view of Fig. 2 along line 4-4, and shows the ink feeding elements and supporting structure;

Fig. 5 is a top plan view of the machine of Fig. 1, and shows in greater detail the power feeding shaft and interconnected gearing for assuring synchronized drive of the various parts, and

Fig. 6 is a side elevation view of another embodiment of the invention, illustrating how three different silk screen rotary printing drums embodying the main features of the machine of Figs. 1 to 5 can be arranged in tandem or cascade for multi-color registrations on the sheet material.

The machine shown in Figs. 1 to 5 comprises a flat table too 60 over which travels an endless conveyer belt 62 of rubber of other suitable material. The belt 62 passes around driven rollers or pulleys 5 and 6 arranged one at each end of the table top. An idler roller 31 serves to maintain tension on the belt 82 and prevents a slack or loose condition of the belt. This idler roller is mounted on a suitable vertical support and is adjustable to provide a desired amount of tension on the belt. It will thus be seen that the belt is constrained to travel in a straight line over the table top.

A pair of aprons 64, 66 are provided on both sides of the bed or table top 60 and on substantially the same horizontal plane.

The table is divided in two parts A and B on the same horizontal plane and these two parts are separated by the distance between lines C and D. A pair of druins 3 and 4 are positioned transversely of the table top and endless belt, and are arranged to cooperate in the space between lines 0 and D for effecting the printing or painting operation. Drum 3 is hereinafterreferred to as the screen drum,while drum 4 is referred to as the pressure drum.

Screen drum 3, in effect, is a frame having two oppositely disposed metallic plates E and F mounted on and rotatably driven by a shaft 21. The silk screen which has permeable and impermeable areas disposed to form a pattern and through which the ink is applied, in a manner to be described later, is stretched between the plates E and F and forms therewith a drum of which the screen is a resilient surface 68. The frame plates E and F of the screen drum are each provided on their outer surfaces with small hooks or studs Hi to which are fastened draw strings or lace work secured to the ends of the silk screen for drawing the silk screen taut on the frame. In effect, the silk screen 68 is made in the form of a hollow tube whose diameter is slightly larger than that of the end plates E and F, and which is provided with draw strings or lace work for securing the silk screen tightly to the outer surfaces of the plates E and F.

The plates E and F of the drum 3 are each provided with a pair of arcuate-shaped apertures H which are symmetrically positioned on opposite sides of the center.

Between the plates E and F are a pair of blocks 12, 14 which are secured to each other by tubular members 16, I8 and flanges 80. Tubular members 16, 18 surround the shaft 21 and are freely mounted on the shaft by suitable bearings, or otherwise. Fastened to both blocks 12, 14 by means of frame 82 extending between them is a rubber squeegee blade 9. Note Figs. 2 and 4. Near each end of the squeegee blade 9 are two adjusting screws I 9 and 20. Screws 1!! serve to provide evenly distributed pressure of the blade on the interior of screen 68, while screws 20 afiect the angle of the suueegee blade relative to the line of contact with the screen. The paint or ink to be forced through the silk screen onto the work or sheet of material by the squeegee is desi nated 84.

The work or sheet of material to be painted is placed on top of the endless belt 62 and advances with the belt between the silk screen drum 3 and the pressure drum 4.

The pressure drum or roller 4 is mounted directly below the silk screen drum, and comprises a hollow cylindrical construction through whose longitudinal axis extends a horizontal rod 86 for supporting the pressure drum. The drum 4 is freely rotatable upon the rod 85. The ends of the rod are supported by vertical columns 88, 90.

- In each vertical column is a sliding block bearing 92 upon which upward pressure is brought to bear by springs 94. It should be understood that pressure drum 4 is free to turn on rod 86 and i; not driven as is silk screen drum 3.

An important feature of the invention lies in the means for maintaining the squeegee blade stationary while the silk screen drum 3 is rotating, thus assuring uniform line contact or pressure of the squeegee on the silk screen 68. To effect this result, there are provided two alternatelymoving rods or rocker arms 14 and I5 whose lower ends are provided with rollers R, R riding on individual cams l6 and i1 arranged at a 90 degree angle, as shown. Cams i6 and H are mounted side by side on a rotatable shaft l8. The upper ends of rocker arms i4 and I5 are linked to horizontally arranged and movable pistons i2 and I3, respectively. These pistons move inand out of the apertures H in the end plate F and into suitable sized holes 92 in block it and are so timed that block 14 is never free from them. In this way block 14 and, by virtue of the rigid connections therebetween, block 12 and the suspended squeegee arrangement are held stationary, while the two plates E and F are rotated by shaft 2 I.

The arcuate-shaped apertures H have such arcuate dimensions that, assuming the direction of rotation indicated by the arrow in Fig. 3, when the solid edge M of plate F (note Fig. 3) is about to move into the position occupied by piston l3, this piston will be withdrawn from block 14 and positioned entirely outside plate F, but at this time piston i2 will be inserted into its associated hole 92 in block 14 through the same aperture H from which the piston l3 was just withdrawn. At a Very short interval of time thereafter, when the other aperture H has reached the position normally occupied by piston l3, this piston will now move through this aperture into its associated hole in block 14. At this particular time, pistons l2 and I3 will both be inserted into block 14 but through different apertures H, H. A short time later, when solid edge M is about to move into the position occupied by piston l2, this piston will be withdrawn from block 14 and positioned entirely outside plate F while piston l3 will be holding block '14 stationary. The timing of the movements of the pistons l2 and I3 are effected by the cams l6 and I1.

Shaft 2| which drives and is linked to the plates E and F of the silk screen drum, receives its power from shaft 22 through sliding coupling 23. The adjustability of coupling 23 enables the drum 3 to be removed, when desired, for changing of the silk screen, cleaning, etc.

The power for driving the machine is connected to shaft 25 (note Fig. 5) which directly drives pulley or roller 6. By means of suitable gears and shafts, as illustrated in the drawing, the pulley or roller 5, the silk screen drum 3 and the cam shaft is are synchronously driven at a desired rate. It is important that the foregoing driven elements be suitably geared so as to rotate at a desired speed relative to the endless belt 62 without slippage, otherwise blurring of the print on the work sheet will occur.

In order to supply ink to the silk screen drum,

the operator need only reach into one of the openings H, whenever necessary, and place a blob of ink onto the squeegee in the position indicated by ink 84 in Fig. 4. If desired, a suitable ink well may be provided.

For drying the printed work sheet after having passed between drums 3 and 4,'there is provided a drying unit 8 which may consist of a suitable number of lighted lamps mounted above the endless belt and supported in a suitable box-like container.

Fig. 6 shows how the machine of the invention can readily be adapted for multi-color printing or registrations. The essential difference between the machine of Fig. 6 and that of Figs. 1 and 5 is the use in Fig. 6 of a lengthened endless belt 62' upon which is placed in tandem a plurality of silk screen drums 3 (here shown as three, for example) and associated pressure drums 4. The silk screen drums in Fig. 6 are supplied with different colored inks and are individually driven in synchronism with pulleys 5 and 6 to prevent slippage and assure perfect registration of colors on the traveling work sheet. The same reference numerals have been used in Figs. 6, 1 and 5 to designate the same elements. Only the essential parts have been illustrated in Fig. 6 in order not to detract from the clarity of the drawing. Drying units may be provided between adjacent screen drums 3 to assure drying of each color and prevent smudging.

Among the advantages of the invention are: Printing through silk screen is fast, efficient and fully automatic with the exception of the ink feed, with drying accomplished while the work is still on the traveling belt; the resilient silk screen drum surface enables uniform printing of work sheets regardless of thickness, flexibility or rigidity of the sheet material; by varying the drive speed, the machine can be driven to suit the capillary action of the paint or ink on various materials; the face of the silk screen coming into contact with the work is alway accessible to the operator for cleaning specks or other accumulation which may tend to clog the stencil; the machine has perfect registration, and can readily be adapted to mass production of multicolor registrations.

What is claimed is:

1. In a stencil or screen type printing machine, a hollow drum having the stencil through which the printing is to be effected, a pressure roller for exerting pressure on said drum, a belt adapted to advance between said drum and roller and carry the work sheet, shaft and gear means for driving both said belt and said drum over separate shafts, a squeegee mounted in said drum and adapted to exert uniform pressure on said stencil over substantially the entire length of said drum, a block located in the interior of said drum and mounted on the drive shaft of said drum for supporting said squeegee, a pair of spaced holes in said block, a pair of pistons located at one end of said drum and each adapted to move into a different one of said holes, a pair of similarly constructed but differently arranged cams for controlling the movement of said pistons, and common drive means for said cams.

2. In a stencil or screen type printing machine, a pair of circular plates spaced apart and fixedly mounted on a drive shaft passing through the centers of said plates, means on said plates for tautly holding a tubular stencil or screen adapted to be passed over said plates, whereby said plates and tubular stencil form a drum, one of said plates having an aperture therethrough, a squeegee located in the interior of said drum and adapted to exert uniform pressure on said stencil over a line of contact, freely mounted means on said shaft linked to and suspending said squeegee, a pair of spaced elements located externally of said one plate and movable in a horizontal direction through said aperture for engaging said freely mounted means in the interior of said drum, and means operating in synchronism with said drum for causing said elements to alternately engage said freely mounted means, to thereby maintain said squeegee stationary at all times while said drum is rotating.

3. In stencil or screen type printing machine, a pair of identical sized circular plates spaced apart and fixedly mounted on a drive shaft passing through the centers of said plates, means on said plates for tautly holding a tubular stencil or screen adapted to be passed over said plates, whereby said plates and tubular stencil form a drum, a squeegee located in the interior of said drum and adapted to exert uniform pressure on said stencil over a line of contact, a pair of spaced interlinked blocks freely mounted on said shaft in the interior of said drum near said plates, means for suspending said squeegee from said blocks, one of said plates having apertures, horizontally positioned pistons adapted to pass through said apertures in said plate and alternately engage one of said blocks, a pair of rocker arms'for moving said pistons, a pair of cams linked to and controlling movement of said rocker arms, and means for synchronously moving said drive shaft and said cams.

4. In a stencil or screen type printing machine, a pair of identical sized circular plates spaced apart and fixedly mounted on a drive shaft passing through the centers of said plates, means on said plates for tautly holding a tubular stencil or screen adapted to be passed over said plates, whereby said plates and tubular stencil form a drum, a squeegee located in the interior of said drum and exerting uniform pressure on said stencil over a line of contact, a, pair of spaced interlinked blocks freely mounted on said shaft in the interior of said drum near said plates, said squeegee being suspended from said blocks, said circular plates of said drum having apertures, horizontally positioned pistons adapted to pass through certain ones of said apertures for alternately engaging at least one of said blocks, a rocker arm individual to each piston for moving the same, a cam for controlling the movement of each rocker arm, and means for simultaneously moving said cams in synchronism with said drive shaft.

5. In a stencil or screen type printing machine, a pair of identical sized circular plates spaced apart and fixedly mounted on a drive shaft passing through the centers of said plates, means on said plates for tautly holding a tubular steeloil or screen adapted to be passed over said plates, whereby said plates and tubular stencil. form a drum, one of said plates having a pair of arcuate-shaped apertures symmetrically positioned on opposite sides of the center of the plate, a squeegee located in the interior of said drum and adapted to exert uniform pressure on said stencil over a line of contact, a block freely mounted in the interior of said drum on said iii? shaft, said block having a pair of spaced horizontally arranged holes on one side of said shaft, a pair of spaced horizontally positioned pistons registering with the holes in said block, and means for causing said pistons to pass through the arcuate-shaped apertures in said plate and to alternately enter said holes in said block, to

chine, a pair of co-extensive circular plates,

mounted on a shaft passing through their centers, circumferentially spaced studs on the exterior surfaces of said plates, a tubular-shaped screen passing over said plates and forming therewith a drum, said screen having circumferentially and uniformly spaced drawstrings at both ends for attachment to said studs, one of said plates having an aperture therethrough, a squeegee located in the interior of said drum and exerting uniform pressure on said stencil over a line of contact, freely mounted means on said shaft linked to and suspending said squeegee, a pair of spaced elements located externally of said one plate and movable in a horizontal direction through said aperture for engaging said freely mounted means in the interior of said drum, and means operating in synchronism with said drum for causing said elements to alternately engage said first means, to thereby maintain said squeegee stationary at all times while said drum is rotating.

'7. In a stencil or screen type printing machine, a pair of circular plates spaced apart and fixedly mounted on a, drive shaft passing through the centers of said plates, means on said plates for tautly holding a tubular stencil or screen adapted to be passed over said plates, whereby said plates and tubular stencil form a drum, one of said plates having an aperture therethrough, a squeegee located in the interior of said drum and adapted to exert uniform pressure on said stencil over a line of contact, freely mounted means on said shaft linked to and suspending said squeegee, a pair of spaced elements located externally of said one plate and movable in a horizontal direction through said aperture for engaging said freely mounted means in the interior of said drum, a pair of cam surfaces for controlling said spaced elements to alternately engage said freely mounted means, and means for synchronously driving said drive shaft and said cams simultaneously and in a positive manner, to thereby maintain said squeegee stationary while said drum is rotating.

THUR J. MURPHY.

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

'n :u- STATES PATENTS

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