US 3842738 A
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Description (OCR text may contain errors)
CONVERTIBLE GRAPHIC PRESS BACKGROUND FOR THE INVENTION For many years the printmaker has been required to use two different types of print presses regardless of size, one for printing lithographs and another for etchings, woodcuts,.linoleum cuts and wood engravings. The same type of press could be used for intaglio printing (etching) as well as for relief printing from blocks but not for lithography. Since presses are expensive and usually represent a lifetime investment, the printmaker had to make a choice and commit his efforts to a single type of work. Accordingly, there has long been an effort to produce a press which could be satisfactorily and quickly converted from one form of printing to the other and vice verse so that this choice of effort could be eliminated. Of course the time factor is important and the change-over should be fast and simple. There have been several forms of combination presses devised which could be adapted to perform all three conventional printing operations. However, so far is known, all have failed for one reason or other but principally on the basis of the failure to accomplish interchangeability easily and effectively, without compromising the printing results for the standard and conventional printing operations.
Recently, there has been a definite up-surge in the printmakers art and the demand for adequate presses has not kept up with the resurgence of the demand.
The graphic press disclosed and described herein was conceived with the over all objectives of providing a press which was fully interchangeable without any compromise due to the interchangeability, and therefore functional to produce the best of lithography and the best of intaglio and relief printings.
In the prior art, the interchangeability attempted has forced compromises from many directions. One is in roller size. Intaglio printers believe, as the result of long experience, that a large roller is much superior to a small one. In the conversions of the prior art the size of the roller was restricted to undersized dimensions. Another is the pressure adjustment to the roller. In most instances the means and method for pressure adjustments are extremely limited and lead to faulty construction. And still another is the roller drive. Since both lithography and intaglio presses, when converted employ the identical frame, the two printing mechanisms required, together with their drives, may be quite different, and caused severe and destructive compromises in the interchangeably of mounting them on the same frame. However, the construction of this press permits the same drive for the intaglio printing if desired without compromising the nature or quality of the results. Each of these compromises as well as any compromise leads to inferior results so far as the operation of the press is concerned, with resulting inferior prints.
SUMMARY OF THE INVENTION The present graphic press is truly an all-around graphic art press. It provides all of the requirements for intaglio printing and relief printing and is readily converted to provide the best features of lithography. It is a sturdy press, constructed of hollow steel members for lightness in weight without compromising in strength, and suitably braced so that the stresses and pressures of all types printing will not be disturbed or distorted by undue flexing and orother movement. In addition the graphic press disclosed is portable as well as demountable. It does not rely on the flimsy construction required for folding but can be assembled or disassembled and transported by one or two persons using only two spanner and two Allen wrenches. Since any material will bend under printing pressure, unless prevented, the present invention provides a rigid central drum which is solid to take any pressures involved. F urthermore there is no waste of weight or cost in trying to make the bed stiff. Contrary to everything shown in the art the bed is flexible enough so that any warpage will easily be flatten during the printing.
One of the great advantages in the interchangeability of the equipment to meet the specific requirements of lithography on one hand and intaglio on the other, is that the press of this invention uses a large roller, i.e., nine inches in diameter, such are employed on a single purpose etching press. This is accomplished by complete removability of the lithography mechanism of the bridge. There would be no room for a nine inch roller where any of the lithographing mechanism was retained to support the intaglio mechanism. Many intaglio printers prefer that the top roller be driven. In this device two points are incorporated from which the' drive crank may be attached. One to drive the bottom roller as in lithography, and the other to drive the intaglio roller, just as the printmaker prefers.
Further objects are to provide a construction of maximum simplicity, economy and ease of assembly and disassembly, also such further objects, advantages and capabilities as will fully appear and as are inherently possessed by the device and invention described herein. The invention further resides in the combination, construction and arrangement of parts illustrated in the accompanying drawings, and while there is shown therein a preferred embodiment thereof, it is to be understood that the same is illustrative of the invention and that the invention is capable of modification and change and comprehends other details of construction without departing from the spirit thereof or the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS:
FIG. 1, is a perspective view of the graphic press set up for lithography;
FIG. 2, is a perspective view of the same press set up for intaglio and relief printing;
FIG. 3, is a fragmentary view partly in longitudinal section and partly in elevation taken on the line III-III of FIG. 1; i
FIG. 4, is a fragmentary transverse section taken on the line IV IV of FIG. 1;
FIG. 5, is a schematic view of a possible power drive;
FIG. 6, is a fragmentary transverse section and elevation taken on theline Vl-VI of FIG. 1, and
FIG. 7, is a fragmentary transverse section and elevation taken on the line VII-VII of FIG. 2.
DESCRIPTION OF PREFERRED EMBODIMENTS Referring now more particularly to the drawings and with particular reference to FIGS. 1 and 2, the frame for the press is constructed so that it is sturdy yet light in weight and yet implementing the fundamental concept of its knockdown portability. While these concepts may appear to be in conflict, they are actually unexpectantly in a harmonious relationship in the present construction. The frame is constructed of side bars 12 and 14 which are rectangular section tubing. Just beyond the mid point of the side bars and right angles thereto, the parallel vertical posts 15a, 15b, 16a, and 161; are welded in position or secured in any other suitable manner. These vertical posts are equally spaced from each other and extend both above and below the side bars 12 and 14. The bottom ends are connected by spacers 17 and 18 which are secured in position in any suitable manner, such as welding. Spaced a short distance from post 16b is a shorter post 19, which is preferably welded to side bar 14. The post 19 may be eliminated if the drive is to be only on the under roller as will be described later. The side bars 12 and 14 are provided with internally extending flanges 20 and 21 which are intended to be flush with the bottom surface thereof and are ground to a smooth, level top surface, to form a track for the level and smooth passage of the bed, as hereinafter described, with the side bars 12 and 14 forming the precision guides. Stops 22 are provided to limit the travel and prevent the bed from inadvertently falling or running off the track.
i The front legs are a pair of V-shaped members 23 and 24 also of rectangular section tubing welded to- 'gether at the bottom or apex 25, together with an inturned foot plate 26. These legs are secured to the side bars under the front portion at either side, legs 23 being secured to the frame members 12 and 14 spaced inwardly from the beginning ends thereof, and leg members 24 being secured to the vertical posts 15a and 16a respectively. The rear legs are also V-shaped, joined at the apex 27 by welding or in any suitable manner, with an in-turned foot plate 28. Leg members 30 are secured to the vertical posts 15b and 16b and leg members 31 are secured to side bars 12 and 14, adjacent rearward ends thereof. It thus appears that rail 12, vertical posts 15a and 15b and spacer 17 plus the secured leg members constitute a unitary section of the press, as does its complimentary substantially identical section at the opposite side. Between the legs 23 in the front a spacer brace 32 is bolted which determines the width of the press and the amount of separation between the side bars 12 and 14. Cross bracing 33 and 34 is bolted to the leg members 24 to maintain the spacing and to give the structure rigidity. Likewise, cross-bracing 35 and 36 is bolted between rear legs 31 to maintain the rigidity and spacing at the rear of the press. It will be observed that by unbolting the cross bracing and spacing members 32, 33, 34, 35, and 36, then unbolting the leg members 23 and 24, 30 and 31 from the side bars 12 and 14 and posts 15a and 16a, the whole press frame can be disassembled quickly, and just as quickly reassembled.
Assembly and disassembly can be accomplished in about one hour by two men and any man can easily carry any of the 'parts. The entire press therefore can be transported in a station wagon. The use of rectangular section tubing for the side bars and legs give unexpected lightness and yet complete rigidity.-
The bed for the press, generally designated 37, is constructed of two sections of laminated fir 38, of substantial thickness in order to provide elasticity under pressure but without distortion. The bed pad comprises a layer of neoprene 40, topped by a galvanized steel sheet 41 which is turned down into a flange at its marginal edges to confine the neoprene sheeting 40. At its front marginal edge the bed 37 is suitably mounted on rollers 42 which travel on the flanges 20 and guide against the inner faces of the side bars 12 and 14. This insures smooth, level travel for the bed 37, without cocking or canting. -1 Also at the outer marginal edge of the bed bracket 43 may be provided which is an outer stop for the bed 37. To this bracket 43 may be secured a hand grip 44 to manually move the bed 37 back and forth on the guide rails 20.
The pressure drum 45 is solid steel with axial stub shafts 47 which fit into self-aligning ball bearings 46. These bearings 46 are mounted at either side between the posts 15a and 15b and between posts 16a and 16b above the spacers 17 and 18 in such a manner as to permit the pressure roller 45 to bear directly against under surface of the bed 37 when it is in level traveling position. This is perhaps best shown in FIG. 3. As the bed 37 passes from left to right resting on the pressure cylinder 45; the outer end is supported by guide wheels 48 mounted on the inner faces of the end legs 31.
A boss 50, is welded to the vertical post 16a above the lbed and on the outer forward face thereof. The boss 50 is bored transversally as at 51 to support a sprocket wheel 52 which rotates on a stub shaft journalled within the bore 51 in the conventional manner. This sprocket 52 is turned manually by hand crank 53. A chain 54, connects sprocket wheel 55, with sprocket wheel 52. The sprocket wheel 55, is splined to the outer end of the stub shaft 47, on the roller 45, so that by turning the hand crank 53, the pressure roller 45, is likewise turned to move the bed in either direction, forward or backward, depending upon the direction of the rotation of the hand crank 53.
It is a simple matter to convert the movement of the press from hand operation to motor operation as will be observed by reference to FIG. 5. A spacer bar 56 may be added between rear legs 30 for the mounting of a motor bracket 57 thereon. The motor 58, drives the sprocket 60 through chain 61 to sprocket 5S. Adjacent the bed 37, along its right marginal edge is mounted a trip 62, which engages a contact 63, electrically coupled to the power input for the motor to shut it off when the trip 63 is activated. This would prevent the driving of the bed inadvertently off of the rails at the back end.
Another feature of the equipment is shown in FIG. 3, and also in FIG. 1. Welded to the forward faces of posts 15a and 16a are bosses 64. Journalled in these bosses is a transverse rotating shaft 65. The shaft is rotated by means of hand lever 66. Secured on the shaft and under the bed 37, are spaced rollers 67. When the hand lever 66 is in the down position, shown in full lines on FIG. 3, the rollers are completely out of operative engagement with the undersurface of the bed 37. As the hand lever 66 is moved upwardly the wheels 67 engage the underside of the bed 37, and raise it out of contact with the drive roller 45, so that the bed will then roll freely on its own rollers '42 and on the rollers 67 and by use of the hand grip 44 can be rolled back and forth without the necessity of turning the hand crank 53. This is a great convenience and time saver.
Up to this point the entire press is identical whether used for lithography, intaglio printing or block printing. FIGS. 1, 3, and 6 show the press as set-up for lithography. In the lithographic set-up, a lithograph stone 70 is shown in its position on the press bed 37. On the inner opposed faces of the vertical posts 15a and 15b, and 16a and 16b, are integral guides 71. These guides function to receive interchangeable portions for both lithograph and for intaglio pinting and are coextensive with the height above the side rails 12 and 14. The scrapper box 72 stretches between the two sets of posts 15 and 16 and guides at either end in the bearing guides 71. The scrapper 73 is attached to box 72 on the undersurface thereof for contact with the tympan covering the material on the lithograph stone 70 during the printing process. The pressure is applied by a yoke which is generally designated 74. The yoke consists of two parallel sheets of steel 75. They are spaced from each other by end spacers 76 and by spring anchors 77. Secured at the central portion between two plates 75 is a bored cylindrical member 78 in which the plunger 80 guides for vertical passage. The plunger 80 is threaded axially towards its lower end to receive the threaded adjusting screw 81 which is rotated by the adjusting hand wheel 82. The hand wheel 82 has a bearing portion 83 which exerts pressure on the scrapper box 72 in accordance with the given adjustment. The plunger also carries transverse wings 89 which bear against leaf springs 84, which in turn are anchored at their outer ends in any suitable manner to the spring anchors 77. The plunger 80 at its top end carries a rotary cam follower surface which it can either be rotating as shown FIG. 6, or just a plain hemispherical or formed surface 85. A hand lever for exerting the pressure which is number 86, is eccentrically rotated around a pivot point 87, which is secured between the two yoke plates 75. The eccentric 88 of the lever arm when bearing against the cam surface 85, forces the plunger downwardly in any increment desired. The four vertical posts 15a, 15b, 16a, and 16b are bored and threaded axially fromthe top to receive the hexagonal machine bolts 90. The end plates 76 of the yoke 74 are L-shaped transverse plates 94 carry four vertical cylindrical centering guides 91, two at each end. The L-shaped end plates 94 rest upon approximately 36 cubic inches of chip board packing 92, at either side and the assembly is held in place by plates 94 and bolts 90. This provides exceptional resilience and will hold, without slippage, any increment of pressure exerted through the pressure arm 86.
The set-up for intaglio and block printing is shown in FIGS. 2 and 7. It is apparent that in order to make the conversion from the lithographic set-up just described, all that is necessary to do is to remove the machine bolts 90 and the yoke 74 can be lifted up and removed as a unit. To lighten the weight, the hand wheel 82 can be used to unscrew the assembly and separate the threaded stem 81 from the plunger 80. The scrapper box 72 and the scrapper 73 itself may be lifted out as a unit and the press is then ready to receive the intaglio components. The large printing roller 100 is placed in position on the press and the bearings are placed on the stub shafts 105 to form a unitary assembly. This unit is then slipped down between the posts where the bearings 10] are guided by the guides 71. When the bearings 101 and the roller 100 are in position, then a spacer and cover plate 102 is placed across the posts a and 15b, 16a and 16b, and the hexagonal machine bolts 90 are replaced in their respective positions and tightened to hold the printer roller and its bearings in position. Micrometer adjustment of pressure on the take-up bearings 101 is accomplished by the screw 103 which bears against the top surface of each take-up bearings 101. The stub shaft for the printing roller has an extension on the right hand side at 105 which is splined to receive the roller drive sprocket 106. The sprocket 106 may be used as the sprocket 55 and vice versa.
All of this presupposes that the drive mechanism for the lithography set-up has been removed, that the sprocket 55 has been removed from shaft 47, that the sprocket 52 has been removed from shaft 51, and that the chain 54 and crank 53 have also been removed.
The drive for the intaglio and block printing requires a separate post 19, which is mounted at right angles vertically upward from the side bar 14. Adjacent the top of the post 19, a stub shaft 108 is journalled for totation therein and carries a small sprocket 110. This shaft and sprocket 110 are rotated by hand crank 111. The sprocket 110, and the hand crank 111 are interchangeable with sprocket 52 and crank 53. The rotation thereof is transmitted through the chain 112, and so rotates the large printing cylinder 100. It will be noticed that the drive for the intaglio and block printing is through the printer roller 100 and not as in the lithographing set-up, through the pressure rollerv45. It is apparent that the drive can be motorized in substantially the same manner as for lithography by attaching the counter-part chain 61 from the motor 58, to the small sprocket drive 108.
OPERATION In the operation of the press for lithography, the lithograph stone 70, is placed on the bed 37, with the printing surface upward. The paper is then placed over the printing surface and then covered with blankets, sheeting and tympan. The top surface the tympan is lubricated for contact with the scrapper 73. The scrapper box 72 and .hence the scrapper itself 73 is lowered to contact the upper lubricated surface of the covering for the lithograph stone 70, by means of the hand wheel 82. The right amount of pressure required for making the print is then made by pulling down on the pressure arm 86. The pull on the cam follower surface 88 moves the plunger 78 downwardly. The wings 89 of the plunger work against the resiliency of the leaf springs 84. This reactive force makes it possible to exert pressure in very small increments without any strain on the lever 86. The cam operated pressure system of the lithography bridge is both simple and positive. Since the cam over-centers only slightly, the printmaker is not required to exert any more force then is actually necessary in securing the precise pressure. Nor is there any danger of the pressure arm 86, being snapped up accidentally. The pressure arm 86 provides a full linear movement at the scrapper 73, greatly facilitating the even handling of the tympan and its lubricant. When the required pressure adjustments have been made, the hand crank 53 is turned clock-wise driving the bed by means of the drive pressure roller 45 through the yoke and under the scrapper 73, from left to right as seen in FIG. 3. One pass in this direction is all that is necessary to make one impression. The top material above the paper and the paper on the lithograph stone 70 are removed. The lithograph stone is then returned to its original position by pulling up on the crank arm 66 and engaging the bed lifter rollers 67 with the bottom of the bed, freeing the bed from the drive roller 45 and permitting the free easy return olthe bed by means of pull ing on the hand grip 44. in this manner the tedious return by turning the crank 53 is eliminated.
The operation of the intaglio printing is very simple. The printing roller 100 which is the large roller with its bearings 101 is lowered in the guides 71 to contact the' face downward on the paper. The appropriate printing pressure is solely at the discretion of the printmaker and is accomplished by adjusting the screw 103, at both sides of the take-up bearing The crank 111 is turned counter clock-wise and this rotates the printing driving drum 100 so that the printing surface on the bed 37 passes under the roller from left to right. The return of the bed to the point of beginning is accomplished in the same manner as before described by using the bed lifter wheels.
Since the speedy conversion and construction of this press permits the use of large sized rollers it is not necessary to change the drive method to the upper roller in intaglio printing. In this manner the post 19 can be eliminated entirely. No lessening of the quality results from driving on the lower roller, because of the use of large sized upper rollers, not possible heretofore.
1. In an interchangable graphic press set up for lithography, a pair of unitary complimentary side members having in co-planar arrangement V-shaped front and rear legs, horizontal side rails with inturned track flanges and parallel upstanding hollow posts two on each side member open at the top and extending above and below said side rails, cross bracing between said side rails determining the width of said press, a'solid roller with its end shafts removably mounted in suitable bearings transversely of saidpress and between said posts at either side below said side rails with the perimeter of said roller in level engagement with the undersurface of a bed. a bed for said press having attached rollers at its outer end for horizontal movement guided by said inturned flanges and resting at its inner end on said solid roller in the preliminary position, a yoke assembly transversely mounted at either side between the parallel upstanding posts and resiliently mounted with spacers, said yoke having an internally mounted eccenand between the upstanding posts.
3. In an interchangable graphic press, a pair of unitary complimentary side members having in co-planar arrangement V-shaped front and rear legs, horizontal side rails with inturned track flanges and parallel upstanding hollow open at the top posts two on each side member extending above and below said side rails, cross bracing between said side rails determining the width of said press, a solid roller with its end shafts removably mounted in suitable bearings transversely of said press and between said posts at either side below said side rails with the perimeter of said roller in level engagement with the undersurface of a bed, a bed for said press having attached rollers at its outer end for horizontal movement guided by said inturned flanges and resting at its inner end on said solid roller in the preliminary position, eccentrically mounted rollers adjacent the solid roller and beneath the bed, said eccentric mounted rollers being normally out of operative engagement with the undersurface of said bed, and means to move said eccentric rollers into operative engagement to lift the bed from contact with said solid roller and facilitate a quick return of the bed to said preliminary position. =l