Patent Application
20090282996
The present invention relates generally to printing presses and more particularly to printing presses with fixed cutoffs.
U.S. Pat. No. 5,868,071 discloses a variable cutoff printing press. The press includes a pair of plate cylinders and a pair of blanket cylinders with all of the cylinders having a cylindrical body and a central axis of rotation. The blanket cylinders are linearly adjustably positionable along the perpendicular to the adjustment axes to adjust the spacing between the plate and blanket cylinders to accommodate blanket sleeves of different thicknesses.
U.S. Pat. No. 5,950,536 discloses a press that has an impression plate mounted on the frame in the case of a non-perfecting press or an identical, mirror image assembly of plate and blanket cylinders in the case of a perfecting press. The plate cylinder sleeve is variable, whereby a length of an image to be printed is varied proportionally to the variable outer diameter while maintaining the outer diameter of the gapless blanket cylinder sleeve constant.
U.S. Pat. No. 7,032,515 discloses mounting a sub-frame on an existing frame of a printing press. New plate and blanket cylinders having different sizes than the plate and blanket cylinders used in the existing printing press may be mounted in the sub-frame to provide different printing lengths/cut offs.
The present invention provides a web printing press printing a web having a first side and a second side including:
a first plate cylinder having a first diameter for printing a first image on the first side of the web; and
a second plate cylinder having a second diameter different from the first diameter for printing a second image on the second side of the web.
The present invention also provides a method of printing a web including the steps of:
printing a first side of the web using a first plate cylinder having a first diameter; and
printing a second side of the web using a second plate cylinder having a second diameter;
the first diameter being different from the second diameter.
A preferred embodiment of the present invention will be elucidated with reference to the drawings, in which:
The ability to print two cutoffs in a single print unit may be advantageous in non-perfecting printing applications where one side of a web is printed at a time. A printing press including a print unit having two print couples, a first print couple with a fixed cutoff and a second print couple with a different fixed cutoff allows a single print unit to print two different cutoffs.
Printing two different cutoffs on a single print unit also may be advantageous during printing applications wherein both sides of the web are printed at the same time. A printing press including a print unit having two print couples, a first print couple with a fixed cutoff and a second print couple with a different fixed cutoff allows a single print unit to print two different cutoffs. For proper registration, the length of the fixed cutoffs may be integer multiples of each other.
A motor 80 drives plate cylinder 22. A second motor 82 drives blanket cylinders 24 and 26. A third motor 84 drives plate cylinder 28. This motor arrangement allows selective contact between plate cylinders 22, 28 and blanket cylinders 24, 26 respectively, for example, for non-perfecting printing or for plate changing. Other motor arrangements, for example, motor arrangements in auto-transfer printing presses, are also preferred.
Printing units 30, 40, 50, 60 and 70 are arranged similarly to printing unit 20. Each printing unit 30, 40, 50, 60, 70 includes two print couples 33, 37, 43, 47, 53, 57, 63, 67, 73, 77. Each print couple 33, 37, 43, 47, 53, 57, 63, 67, 73, 77 includes one plate cylinder 32, 38, 42, 48, 52, 58, 62, 68, 72, 78 and an associated blanket cylinder 34, 36, 44, 46, 54, 56, 64, 66, 74, 76, respectively. Printing press 10 also includes a roll 14 and a windup roll 16. Web 12 travels from roll 14 to windup roll 16. After web 12 is printed by printing units 20, 30, 40, 50, 60, 70, web 12 is dried by a dryer 18. Windup roll 16 can then be removed and cut to a proper size, for example, for packaging material. Furthermore, the printed web may be delivered to another printing device, for example, a coater, a rewinder, a sheeter, a folder or other inline finishing device.
During a non-perfecting printing application where print couples 23, 33, 43, 53, 63 and 73 are printing on web 12, cutoff is 22 inches when radius RP1 is 3.50 inches. During a non-perfecting printing application wherein print couples 27, 37, 47, 57, 67 and 77 are printing on web 12, cutoff is 28 inches when radius RP2 is 4.46 inches. Thus, printing press 10 permits two different cutoffs, 22 inches and 28 inches, on web 12.
In a printing couple, it is preferable for the blanket cylinder to have a radius similar to the associated plate cylinder radius or an integer multiple thereof. For example, in printing couple 23 the radius RP1 of plate cylinder 22 is 3.50 inches and the radius RB1 of blanket cylinder 24 is 3.50 inches also.
A second embodiment of the present invention, printing press 110, is shown in
Each plate cylinder and blanket cylinder may include printing plates and blankets respectively. As shown in printing unit 120, a printing plate 222 is mounted on an outer circumference of plate cylinder 122 and a printing plate 228 is mounted on an outer circumference of plate cylinder 128. A blanket 224 is mounted on blanket cylinder 124. A blanket 226 is mounted on blanket cylinder 126. Blankets 224, 226 may be gapless, axially removable blanket sleeves.
In another preferred embodiment shown in printing unit 130, plate cylinders may include multiple plate lock-up mechanisms carrying multiple printing plates. Plate cylinder 138 includes two plate lock-up mechanisms 160 and 162. Two printing plates 238 and 239 are mounted on plate cylinder 138. Printing plates 238 and 239 may carry a same image or different images. In a further preferred embodiment shown in printing unit 140, plate cylinders 142, 148 may be imaged directly and need not carry printing plates.
A motor 180 drives plate cylinder 122. A second motor 182 drives blanket cylinders 124 and 126. A third motor 184 drives plate cylinder 128. This motor arrangement allows selective contact between plate cylinders 122, 128 and blanket cylinders 124, 126, respectively, for example, for non-perfecting printing or for plate changing. Other motor arrangements, for example, motor arrangements in auto-transfer printing presses, are also preferred.
Printing units 130, 140 and 150 are arranged similarly to printing unit 120. Each printing unit 130, 140, 150 includes two print couples 133, 137, 143, 147, 153, 157. Each print couple 133, 137, 143, 147, 153, 157 includes one plate cylinder 132, 138, 142, 148, 152, 158 and an associated blanket cylinder 134, 136, 144, 146, 154, 156, respectively. Printing press 110 also includes a folder 104 including roll top of former 106, nip rollers 108, cutting cylinders 114 and a fan 116. Web 112 travels through printing section 102 and folder 104 where the web may be processed and folded into printed products.
During a printing application where both sides of web 112 are printed at the same time, the radius of printing plates 128, 138, 148 and 158 should be an integer multiple of the radius of printing plates 122, 132, 142 and 152. This relationship between radius RP3 and radius RP4 is needed to keep proper circumferential registration of images printed on web 112. For example, printing plate 122 has a radius RP3 of 3.50 inches and a cutoff of 22 inches. Printing plate 128 has a radius RP4 of 7.00 inches and a cutoff of 44 inches. Radius RP4 of printing plate 128 is two times radius RP3 of printing plate 122. Thus, two images are printed on web 112 by blanket cylinder 124 via plate cylinder 122 in the same length one image is printed on web 112 by blanket cylinder 126 via plate cylinder 128.
In
In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.
