US2845858A - Silk screen printing machine - Google Patents

Description

Aug. 5, 1958 w, DENLEY 2,845,858

SILK SCREEN PRINTING MACHINE Filed June 14, 1956 3 Sheets-Sheet 1 105 I F I V I 42: BY 4 Aug. 5, 1958 s.'w. DENLEY 2,845,853

- SILK SCREEN PRINTING MACHINE Filed June 14, 1956 3 Sheets-Sheet 2 3 Sheets-Sheet 3 S. W. DENLEY SILK SCREEN PRINTING MACHINE Aug. 5, 1958 Filed June 14, 1956 INVENTOR.

lines of presses has resided through the silk screen.

United States Patent 2,845,858 SILK SCREEN PRINTING MACHINE Sidney W. Denley, Morton Grove, 111. Application June 14, 1956, Serial No. 591,468 1 Claim. (Cl. 101123) The present invention pertains to the art of printing, and more particularly, to improvements in a machine or press for mechanizing the silk screen printing process".

The silk screen method of printing is relatively ancient and has for many years past beenconducted solely by hand. In comparatively recent years, mechanisms and machines have been developed for carrying out such process. For the most part, these machines have been economically favorable from a production standpoint, but have lacked the control of accuracy and quality found in the time honored hand process. Generally, the silk screen printing presses developed to date have employed a rotating drum or cylinder upon which the stock to be printed is rolled during the printing operation for cooperation with a silk screen which is reciprocated in contact with the stock. Still veloped along lines more parallel to the hand method in whicha planar screen is brought into contact withplanar stock or vice versa and a squeegee carrying a suitable printing medium, such as ink or paint, is passed over the upper surface of the screen to force the ink through designated printing areas of the screen leaving the same in deposit or print on the underlying stock.

One of the outstanding difficulties encountered in both in the distribution of the printing medium in an even and uniform manner by a mechanizedsqueegee. Additional ditficulty has been encountered in controlling the amount of ink applied so as to get uniform application and avoid waste.

My present invention seeks to improve presently known mechanized silk screen process printing machines and particularly to present advancements in mechanisms operating the printing squeegee and regulating the amount of ink presented to such squeegee for its distribution Generally, I seek to provide a squeegee movable over the upper face of the printing screen along an orbit of parallelism therewith coupled with a means for intermittently providing printing ink or medium to the squeegee at the initial stages of its operating stroke; the amount of ink supplied to the squeegee being regulated to an amount sufiicient for a single printing application thus avoiding a pile-up of ink at bothends of the screen and leaving the upper face of such screen clean of an excessive amount of such ink.

The main object of my invention is to provide a new and improved silk screen printing press.

Another object of my invention is to provide improved printing means in a silk screen printing press for applying printing medium to and across the printing screen.

Still another object of my invention is to provide a new and improved means for regulating the supply of ink presented to the movableprinting means of the character aforesaid.

A still additional object of my invention is to provide a new printing press for silk screen printing in which improved means are provided to control the supply and other machines have de- 2,845,858 Patented Aug, 5, 1958 2 application of the printing medium thereby to produce better product control.

The above and further objects, features and advantages of this invention will appear to those familiar in the art from the following detailed description and specifications of a preferred embodiment thereof illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a perspective view of a preferred silk screen printing press embodying the features and concepts of my invention;

FigureZ is a cross-sectional View of the printing press seen in Figure 1 with the left hand side plate removed;

Fi ure 3 is a crass-sectional view looking downwardly at the upper side of the printing press of Figure 1 and substantially along line 3, 3 of Figure 2 as indicated by the arrows on that line;

Figure 4 is a cross sectional view along line 4, 4 of Figure 3; and

Figure 5 is a partial enlarged cross sectional view taken along line 5, 5 of Figure 3 looking in the direction of the arrows thereon to illustrate the features and details of the improved printing mechanism of my invention.

Turning now to the features of the improved printing press as illustrated particularly in Figures 1 and 2 of the drawings, it will be understood that the press therein,

taken substantially indicated generally by numeral 10, comprises a pair of vertically u'prig'h't ground engaging pedestals or side frame plates 11, 11 which are held in their spaced relationship by a lower disposed bed plate structure 12 and transverse support bars 13, 13. Mounted on the bed frame structure 12 and intermediate the transversely related cross supports 13, 13 is an electrical drive motor 14 and a gear reducer unit 15 for purposes which will appear presently. Intermediate the side frame plates 11, 1 1 and related transversely thereto, so as to be hor'iiontally disposed, are a pair of parallel shafts 16, 16 each upporting' a roller means 17 over which a plurality of delivery belts 18 are trained. Additional belts 19 engage the lowermost roller 17 between belts 18 to complete the delivery system according to known practice. It is to be noted that rollers 17 are common to a plane angled to the horizontal and inclined in continuation with the plane of a bed frame structure 20. Each shaft 16 bears a sprocket member 21 at its one end arid a drive chain means 22 extends between such sprockets in a continuous circuit (see Figure 2).

Also extending between the parallel side frame plates 11, 11 is a main cam shaft 25 hearing two plate cain means 26, one adjacent each end thereof inwardly of the two frame plates 11, 11. Idler shaft 27 is disposed slightly below shaft 25 and to the right thereof as viewed in Figure 2; such shaft being in vertical alignment with over-disposed stub shafts 28, 28 projecting from the opposed faces of frame plates 11, lladjacent the upper end of the machine and asociated with the operation of an improved printing squeegee assembly 30 of my invention. Stub shafts 28 are parallelled by additional stub shafts 29 mounted in spaced parallelism thereto and located above and to the left of the same as viewed in Figure 2; shafts 28 and 29 defining thereby an inclined plane parallel to which the printing squeegee assembly 30 is activated as will appear presently.

Mounted adjacent the printing assembly 30 to cooperate therewith in supplying the same with necessary printing medium, is an ink feed assembly 31 movable along the top of a printing screen assembly 32, the latter which comprises a-rectangular frame across which a printing screen 32a isstretched; the frame being held at its four corners by bracket means 33 mounted to the inside face of the side frames 11 and the outer ends of a pair of inclined extension arms 34, 34. Arms 34 are attachable at their lower ends to the side frame members 11 and are cross-connected at their outer ends, as by bar or rod means 35. Note in this regard, that arms 34 parallel the plane of the screen member 32a.

Drive mechanisms In order to motivate the several portions of my improved press, the basic elements of which are set forth above, I will now describe the power or driving connection between the motor 14 and the several mechanisms activated thereby.

From Figure 2, especially, it will be seen that motor 14 drives the gear reducer unit 15 through means of a pair of sheave wheels 36 and 37 mounted, respectively, on output shaft 38 of the motor 14 and input shaft 39 of gear reducer 15. Gear reducer 15 has an output shaft 40 which supports a pair of chain sprockets 41 and 42; the latter being the smaller of the two. Sprocket 41 engages a first drive chain means 44 which is trained over a drive sprocket 45 mounted on shaft 27 whereby the latter is rotatably driven. Shaft 27 also supports, adjacent its opposite ends, sprocket members 46 around which secondary drive chains 47 are trained. Each chain 47, engages an over-disposed sprocket member 48 carried on one of the stub shafts 28. Each stub shaft 28 also supports a second sprocket member 49 which rotates in response to the rotational driving of sprocket 48 to drive a chain member 50 trained around sprocket 4S and a similar sprocket 51 mounted on an associated stub shaft member 29 adjacent the upper end of the machine. Note that activation of the large drive sprocket 41 and the gear reducer means 15 serves to rotatably activate sprockets 49 and 51 and thereby drive chain means 50 interconnecting the same.

The smaller sprocket 42 mounted on the output shaft 40 of the gear reducer unit 15 is engaged by a second drive chain means 55 which trains around a larger sprocket wheel 56 mounted on shaft 25 associated with the two cam members 26. Shaft 25 also carries a smaller secondary sprocket 57 which is joined with a driving sprocket 58 at one end of the lowermost shaft 16, as by chain means 59. Rotation of shaft 40 and sprocket 42 thereon thereby serves to rotatably drive the shaft 25 and the eccentric cam means 26 thereon as well as the delivery belt drive chain 22 trained over sprockets 21, 21 carried by shafts 16, 16.

The bed frame or assembly 20, 20 is provided to support paper stock during the printing operation and comprises a pair of parallel spaced apart side arms or rails 60, 60 which are secured together by one or more cross members 61 to constitute a rigid structure. A suitable supporting plate 62 is carried between the two arms 60, 60 to provide a planar support for receiving stock to be printed on.

The side arms 60, 60 together with the plate 62 are mounted for rocking movement about the lower of the two shafts 16 through the extension of the arms 60 which carry shaft receiving boss portions 63 at their lowermost ends receptive of the shaft means 16 (see Figure 1).

In order to provide proper rocking actuation of the bed frame 20, a pair of rocker arms 65, 65 are pivotally supported inwardly of the two side frames 11, 11 as on shaft means 66. The rocker arms 65 each carry a roller means 67 at one end which engages the periphery of the respectively associated cam means 26 on shaft 25. Each arm is biased by spring means 63 or like means for urging the roller 67 thereon into engagement with the profile of the cam plate 26. The outer end of each rocker arm 65 is pivotally connected to an adjusting link 69 pivotally joined to one of the arms 60 of the bed frame, as by pivot means 70.

It will be understood from Figure 2, in particular, wherein the profile of cam means 26 is illustrated, that actuation of the cam means results in a periodic lowering and raising of the bed frame assembly 20 about its pivot axis as defined by the lowermost shaft 16. This actuation permits the insertion of paper stock on the upper side of the plate means 62 followed by the subsequent raising of the bed frame 20 to bring the paper stock in close registration with the underface of screen 320. Suitable stop fingers (not shown) are used for automatically arresting the paper stock on the bed plate in proper registry for the printing operation. After the printing cycle has been completed and bed frame 20 is again lowered, the referred to stop fingers release the sheet so that the same may be delivered to the transfer and delivery belt means 18, 18 carried by the drum means 17 and driven in response to rotation of the two shaft means 16 which are carried by suitable bearing means 71 carried by the side frame members 11.

From the foregoing, it will be understood that paper stock or other material to be printed is periodically fed between the bed plate 62 and the overlying screen assembly 32 for receiving printing ink in response to activation and operation of my improved squeegee or printing assembly 30, as will now be described.

Squeegee assembly With reference to Figures 3, 4 and 5 of the drawings, it will be seen that my improved squeegee assembly 30 comprises an angle bar 75 which extends between chain members 50 and is secured at its opposite ends to a pair of crank arms 76. The crank arms 76 are each pivotally connected at their upper ends to a slide member 77 carried on a. slide rod 78 mounted along opposite sides of the screen assembly 30 between bracket members 79 and 80, mounted respectively on a side frame member 11 and adjacent the outer end of an extension arm 34. The connection of each end of angle bar 75 to an arm 76 is by pivot rod means 81 which passes across the width of screen 32 and through the two arms 76 adjacent their lower ends for connection at its ends with the chains 50. Rod 81 carries two rollers 82, outwardly of each arm 76, which engage guide bars 83 extending between the two stub shafts 28 and 29 that carry the sprocket members 49 and 51. Each end of bar 75 is fixed to a bracket means 84 having spacer pins 85, 85 which carry an adjustment plate 86 of semi-circular shape disposed adjacent the arms 76. A slotted opening 87 is formed in each plate 86 for receiving an adjusting bolt means 88 which is fixed to the adjacent arm 76. With this arrangement, plate 86 and attached bar 75 may be tilted at various angles, within the limits of the slots 87, relative to the plane of the underlying silk screen assembly 32. This relation is best seen in Figure 5.

With the above described arrangement, it will be understood that the driving of chains 50 causes crank arms 76 and bar means 75 attached thereto to move along the orbit described by the encircling path of the chains 50; the upper ends of the crank arms 76 being reciprocated with sliding movement along the slide rods 78. It will be recognized also that the angular relationship of bar 75, as dictated by the adjustment of the bolts 88 in slots 87, is maintained at a constant relation with respect to the plane of the silk screen as it passes along both the lower and upper runs of the chain means 50. The movement of the bar means 75 on the lower run of chain 50, or that is, run 5012, is from the lowermost disposed end of the screen assembly 32 toward the upper end thereof according to the movement of the link chains 50. Movement along the upper chain flight, is in a reverse direction.

To an outwardly extending flange portion 90 of bar 75 are threadingly mounted a plurality of adjustment screw means 92 having manual engageable knobs or wheels 93 thereon. The lower ends of these adjustment screws 92 engage the upper end of a squeegee support means comprising a back plate 94, a face plate 95, a spacer plate 96 and a resilient rubber squeegee 97. It will be recognized that the spacer plate 96 andsqueegee "97 are tsandwiched between the back and front plates'94 -.and:95, withthe squeegee member 97 being fixed in its position v.a's bypin members 98. The three plates 94,95 and 96 bear several enlarged openings therethrough which are registeringly aligned to provide adjustment openings 99, as shown plainly in Figure 5. Through each adjustment opening 99 is passed an adjustment bolt means 100 which also passes'through the angle bar 75. lnthe particular embodiment illustrated, two such adjustment bolts 100 are employed, one adjacent either end of the squeegee assembly. By loosening the bolt means 100, the positioning of the squeegee member 97 relative to the angle bar 90 may be regulated through threading adjustment of the screw members 92. By this arrangement, even contacting pressure of the resilient squeegee member 92 with the silk screen assembly is gained.

As will best be understood by examination of Figure 2 of the drawings, the squeegee means 30 is movable with the chains 50 around the two sprockets 49 and 51 in such a manner that the squeegee member 97 is always positioned downwardly or pointing toward the underlying screen during its movement with both the lower and upper runs of chain 50. With this action, the squeegee may pick-up paint or ink deposited near and adjacent the lower end of the screen and evenly wipe the same across the surface of the screen for the printing operation. The squeegee is guided in such movement and maintained in pressure contact with the silk screen by the action of rollers 82 which engage the lower edge of the guide bars 83 during the squeegees printing stroke and ride on the upper edge of such bars during the return stroke thereof.

Ink distributor means To assist the action of the squeegee assembly 30, as hereinabove described, and to insure that the same picks up the proper amount of ink at the start of its printing stroke, or that is, as the squeegee moves with the lower run of the chains 50 in surface engagement with the screen assembly 30, I have devised a unique means for placing a proper amount of printing medium such as ink or paint in the path of the squeegee 97 and at the commencement of its printing cycle adjacent the lower end of the screen assembly. Features of this unique distributor means, indicated generally by numeral 31, will now be set forth.

According to conventional practice, a puddle of paint or ink is normally disposed at the lower end of the screen assembly in the frame surrounding the screen 32a, for distribution by the squeegee means which serves to carry the same upwardly across the face of the screen and squeeze the same evenly through openings therein for printing according to a desired design. The present practice employing such a squeegee action normally requires or permits the squeegee to convey a puddle of paint or ink across the entire face of the screen with the excess ink being deposited along the upper edge of the screen. As long as the squeegee activity continues, this arrangement keeps the excess paint outwardly of the printing portions of the screen, but when the machine is shutdown for any reason and the squeegee activity is interrupted, this excess ink is prone to leak downwardly passing through and across the face of the screen in an undesirable fashion. It is therefore my concept that if the squeegee assembly 30 is provided with the proper amount of paint or ink at the start of its printing operation, a minimum excess or no excess will be deposited adjacent the upper edge of the screen as the squeegee is lifted upwardly therefrom for its return stroke or movement with chains 50.

In order to accomplish this, I have devised an improved distributing means 31 comprising a first rod member 101 which extends across the width of the screen assembly and two spool members 102 adjacent its ends which receive upwardly turned end portions 103 of a second rod member 104 which r'ideslQosely on the upper face of a bell crank leverarrangement with'secondary arm members .110 each having a roller; means 111 at its one rend for engagementwith one of the cam-members-26it The opposite ends of levers are supported on stub shaft means 112 projecting inwardly of the side frame members 11, 11; it being understood that there are two such crank and lever arrangements, one adjacent each end of the machine for cooperation with each of the two provided cam members 26. Variation in the stroke or arcuate movement of the outer end of the levers 108 is provided through eccentric connection between the lower ends of such arms 108 and the levers 110 and comprising a connector pin means 113. With this arrangement then, the stroke or movement of the distributor rod 104 along the lower portion of the screen to distribute ink upwardly into the path of movement for the approaching printing squeegee 97. By varying the length of the stroke of the arm 108 through adjustment of eccentric pin 113, the amount of ink deposited forwardly of the printing squeegee 97 as the same approaches or engages the screen at the start of its printing stroke may be accordingly varied, thereby to regulate the quantity of ink carried upwardly across the face of screen 32a.

From the foregoing, it will be understood that I am thus able to regulate the amount of ink provided in front of the printing squeegee and thereby to avoid surplus quantities of printing ink on the face of the screen as well as its buildup or deposit adjacent the screens upper end. It will be recognized also that by driving the paint distributing means 31 from the same cams 26, 26 which are utilized to raise and lower the bed frame assembly 20 and by driving such cam means 26 off the output shaft 40 of the gear reducer unit 15 which is common to the drive of the chains 50 serves to establish necessary synchronizati-on of movement between the printing squeegee, the paint distributing assembly and the bed frame assembly 20.

It is believed that those familiar with the art will appreciate and recognize the improved press, squeegee and paint distributing means of my present invention and will recognize the described unique features as marked advancements in this art. Furthermore, while I have herein shown and described my invention in conjunction and association with a preferred embodiment thereof, it is to be understood that numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of my invention. As a consequence, it is not my intention to be limited to the particulars of the preferred embodiment of my invention herein shown and described, except as may appear in the following appended claim.

I claim:

A silk screen printing press, comprising, a main frame, a bed means mounted on said frame for receiving a sheet of material to be printed, screen means supported over said bed frame at an incline to the horizontal, means for moving said bed frame ar-cuately toward and away from said screen means and for arresting the same at periodic intervals in underlying parallelism therewith, squeegee means for applying ink to the upper face of said screen means, endless chain means supporting said squeegee means and driving the same in an orbital path over said screen means, the said squeegee means engaging said screen means adjacent one end thereof, moving thereacross, and disengaging therefrom adjacent the opposite end thereof for application of the ink thereto, adjustable means interconnecting said squeegee and chain means for regulating said squeegee means at preselected angles with respect to the plane of said screen means, the angle of said squeegee being maintained throughout its travel along said orbital path, bar means traversing said screen means and located adjacent the one end thereof for distributing preselected quantities of ink to said squeegee means, and linkage means for operating said bar means to reciprocate the same between a position adjacent the said one end of said screen and a point intermediate the ends thereof, the said intermediate point of movement for said bar means being located slightly in advance of the initial point of contact between said 10 2,688,917

squeegee and screen means, and means for regulating the limits of travel for said bar means thereby to adjust the quantity of ink deposited thereby in advance of the said initial point of contact.

References Cited in the file of this patent UNITED STATES PATENTS Reinke May 29, 1951 Reinke Sept. 14, 1954

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