Patent Grant
8850975
The present invention relates generally to printing units and more specifically to printing units of variable cutoff web offset printing presses.
U.S. Pat. No. 5,813,336, which is hereby incorporated by reference herein, discloses a printing unit with a rotatable print cylinder and a rotatable blanket cylinder. A tubular printing blanket is removably mounted on the blanket cylinder. The printing unit may have an imaging unit mounted therein. A printing member, which is mountable on the print cylinder, is imaged by the imaging unit inside the printing unit. The printing member has a continuous surface and may be removed axially from the print cylinder. The printing unit may be configured as a cantilever printing unit, or, alternatively, may be configured with both a gear side frame and a work side frame for supporting the print and blanket cylinders. In order to provide a variable-cutoff capability, a plurality of print cylinder saddles may be provided. Each print cylinder saddle has the same inner diameter for mounting on the print cylinders. However, in order to provide a variable cut-off, the print cylinder saddles may have a variety of outer diameters.
U.S. Pat. No. 6,694,877 discloses a printing assembly including an image printing cylinder, a transfer printing cylinder and an impression printing cylinder. The image printing cylinder is supported in a fixed position with respect to a U-shaped supporting construction, the transfer printing cylinder is supported on both ends between two supporting elements and the impression printing cylinder is supported on both ends between two supporting elements. The supporting elements are connected to respective bearing arms that are rotatable about a single axis. The bearing aims of the transfer printing cylinder are each rotated by respective first actuating means and the bearing arms of the impression printing cylinder are each rotated by respective second actuating means. The second actuating means are connected to the bearing arms of the transfer printing cylinder, causing the second actuating means to move along with a rotation of the bearing arm of the transfer printing cylinder if the first actuating means are actuated.
A variable cutoff printing unit is provided that includes a plate cylinder, a plate cylinder support removably supporting the plate cylinder, a blanket cylinder; a blanket cylinder support removably supporting the blanket cylinder, a sliding element coupled to the blanket cylinder support for moving the blanket cylinder support toward and away from the plate cylinder support, and a stopping device for stopping movement of the sliding element to limit the movement of the blanket cylinder toward and away from the plate cylinder to a defined range.
Also, a variable cutoff printing unit is provided that includes a blanket cylinder, an additional cylinder, a blanket cylinder support removably supporting the blanket cylinder, the blanket cylinder support including a first face and a second face that define a slot in the blanket cylinder support, an additional cylinder support removably supporting the additional cylinder, the additional cylinder support adapted for lifting the blanket cylinder support, an arm extending into the slot, the arm being movable between contact with the first face and contact with the second face by the impression cylinder support lifting the blanket cylinder support.
A method of operating a variable cutoff printing unit including a blanket cylinder support having a slot formed therein, an additional cylinder support, an arm extending into the slot, a sliding element coupled to the arm and a stopping device is also provided. The method includes setting a position of the blanket cylinder support by contacting the stopping device with the sliding element as the arm contacts a first face of the slot formed in the blanket cylinder support; and contacting the blanket cylinder support with the additional cylinder support so that the arm moves away from the first face of the slot.
The present invention is described below by reference to the following drawings, in which:
a schematically shows a front view of a variable cutoff web offset printing unit including the support apparatus shown in
b schematically shows the printing unit shown in
c schematically shows the printing unit shown in
a and 5b show axial views of blanket cylinders according to an embodiment of the present invention.
A variable cutoff printing unit as used herein refers to a printing unit that can be modified between print jobs so that the printing unit can print repeating images of different lengths during different print jobs. The length of the repeating images printing during a particular print job is commonly referred to as a cutoff length or a cutoff. Plate cylinders and blanket cylinders that print the repeating images for the particular print job (and the plates and blanket mounted on the cylinders) may be said to have that cutoff length or cutoff. For example, a variable cutoff printing unit can print repeating images of a first cutoff length on a web or other substrate during a first print job and then can print repeating images of a second cutoff length that varies from the first cutoff length on a web or other substrate during a subsequent second print job. The first print job is printed using a first printing plate and a first printing blanket each having an outer circumference of a length corresponding to the first cutoff length. After the first print job and before the second print job, the first printing plate and the first printing blanket are removed from the printing unit and replaced with a second printing plate and a second printing blanket that each have outer circumferences of a length corresponding to the second cutoff length. A change between print jobs that involves replacing printing plates and blankets having a first cutoff length with printing plates and blankets having a second cutoff length may be referred to as a cutoff change.
On gear side 10a, support apparatus 10 includes an arm 28, a sliding element 32 and blanket cylinder support actuator 24 for moving blanket cylinder support 16. Arm 28 is connected to sliding element 32 and can couple sliding element 32 to blanket cylinder support 16 so actuator 24 can lift blanket cylinder support 16. Sliding element 32 slides in a frame slot 34 formed in frame 12 that extends vertically within frame 12. As shown in
Slot 30 is vertically wider than a portion of the roller cam within slot 30 so that the roller cam may be moved from a first position where the roller cam contacts an upper face 30a of slot 30 to a second position where the roller cam contacts a lower face 30b of slot 30. When the position of arm 28 is fixed and impression cylinder support 18 does not support blanket cylinder support 16, arm 28 supports blanket cylinder support 16 and upper face 30a rest on the roller cam of arm 28. When impression cylinder support 18 is forced upward by the impression cylinder support actuator 26 so that impression cylinder support 18 lifts blanket cylinder support 16 upward, the roller cam of arm 28 is moved out of contact with upper face 30a and into contact with lower face 30b. In this position, which corresponds to the printing position for the cylinders supported by supports 14, 16, 18, arm 28 prevents blanket cylinder support 16 and impression cylinder support 18 from being moved further upward by contacting lower face 30b.
Blanket cylinder support 16 and impression cylinder support 18 each include respective cams 36, 38 that contact one another so actuator 26 can lift blanket cylinder support 16 via impression cylinder support 18 into printing position. Impression cylinder support 18 includes a cam actuator 40 coupled to impression cam 38 for moving a wedge 41 on impression cylinder support towards and away from pivot point 22. Movement of wedge 41 by cam actuator 40 toward and away from pivot point 22 causes an angled top surface of wedge 41 to slide against an angled bottom surface of impression cam 38 so impression cam 38 rotates about a pivot 42 to move impression cam 38 toward and away from blanket cam 36. As a result, cam actuator 40 may adjust a distance between centers of cylinders supported by supports 16, 18 to properly position the cylinders for printing based on a desired nip pressure and the thickness of a web to be printed. In other embodiments, only blanket cam 36 may include a cam actuator or both blanket cam 36 and impression cam 38 may include cam actuators. In a preferred embodiment, cams 36, 38 are shaped to have curvatures such that, without adjusting cam 38 with cam actuator 40, movement of impression cylinder support 16 by actuator 26 automatically gives the preferred distance between a center of the blanket cylinder supported by blanket cylinder support 16 and a center of the impression cylinder supported by impression cylinder 18.
Actuator 26 may pivot impression cylinder support 18 about pivot point 22 downwardly to move impression cylinder support 18 to an off impression position. As shown in
On work side 10b, support apparatus 10 includes an arm 28′, a sliding element 32′ and blanket cylinder support actuator 24′ for moving blanket cylinder support 16′. Arm 28′ is connected to sliding element 32′ and can couple sliding element 32′ to blanket cylinder support 16′ so actuator 24′ can lift blanket cylinder support 16′. Sliding element 32′ slides in a frame slot 34′ formed in frame 12′ that extends vertically within frame 12′. As shown in
Blanket cylinder support 16′ and impression cylinder support 18′ each include respective cams 36′, 38′ that may be configured and operate in the same manner as cams 36, 38 (
Support apparatus 10 may include an adjustable stopping device 90′ that may be used to set an appropriate center distance of cylinders supported by plate cylinder support 14′ and blanket cylinder support 16′. In a preferred embodiment, adjustable stopping device 90′ may be coupled to sliding element 32′ on the opposite side of frame 12 as actuator 26′ (
Adjustable stopping device 90′ sets a position of adjustable block 47′ that prevents sliding element 32′ from being moved further upward, but allows blanket cylinder support 16′ to be moved closer to plate cylinder support 14′ because roller cam 100 can move vertically within slot 30′ between faces 30a′, 30b′. Adjustable block 47′ limits the vertical movement of sliding element 32′ to set a printing position of a blanket cylinder supported by blanket cylinder support 16′ by setting the position of roller cam 100 of arm 28′. In other words, adjustable stopping device 90′ stops upward movement of arm 28′ and limits the vertical movement of blanket cylinder support 16′ toward the plate cylinder support 14′ based on a range defined by a distance between faces 30a′, 30b′ and a size of roller arm 100. When sliding element 32′ is moved upward so that stop 44′ is moved into contact with the adjustable block 47′ at the top of stop guide slot 45′ and blanket cylinder support 16′ is not lifted by impression cylinder support 18′, upper face 30a′ rests on roller cam 100. In this position, impression cylinder support 18′ may then lift blanket cylinder support 16′ until lower face 30b′ of slot 30′ contacts roller arm 100 so that the blanket cylinder supported by blanket cylinder support 16′ is in a printing position (i.e., in contact with the impression cylinder supported by impression cylinder support 18′ and the plate cylinder supported by plate cylinder support 14′). To change the cutoff accommodated by support apparatus 10, the vertical position of stop 44′ is adjusted by actuator 92′. For example, to modify support apparatus 10 to accommodate cylinders that have a smaller cutoff length than support apparatus 10 is currently set to accommodate, smart motor 48′ may rotate threaded rod 46′ so adjustable block 47′ slides upward in guide 49′. Then, sliding block 32′ may move upward until stop 44′ contacts adjustable block 47′ at the top of stop guide slot 45′.
a to 3c schematically show a front view of a variable cutoff printing unit 50 including support apparatus 10 shown in
Adjustable stopping device 90 is constructed in substantially the same manner as adjustable stopping device 90′ and is provided on gear side 10a for setting the center distances between plate cylinder 54 and blanket cylinder 56. Adjustable stopping device 90 also includes stop 44 connected to sliding element 32, adjustable block 47 that has a stop guide slot 45 formed therein, a guide 49 that guides adjustable block 47 along sliding element 32 and an actuator 92, which may include threaded rod 46 and smart motor 48, coupled to adjustable block 47 for adjusting a vertical position of adjustable block 47 with respect to frame slot 34. Adjustable stopping device 90 may also include a bracket 51 between smart motor 48 and threaded rod 46 for coupling adjustable stopping device 90 to frame 12. Thus, gear side 10a may be adjusted in substantially the same manner as work side 10b to support cylinders of varying cutoffs.
In
In
In
The position of adjustable blocks 47, 47′ sets the printing position of blanket cylinder 156, which is used to set the printing position of impression cylinder 58. When a print job of a particular cutoff length is to be printed by printing unit 50, adjustable blocks 47, 47′ are positioned based on diameters of a plate cylinder and a blanket cylinder for the print job. Because in the embodiment shown in
For a cutoff change that involves setting up printing unit 50 for a smaller cutoff than a print job most recently printed by printing unit 50, adjustable blocks 47, 47′ are moved upward parallel to frame 12 and blanket cylinder supports 16, 16′ are moved toward plate cylinder supports 14, 14′. When actuators 24, 24′ position sliding elements 32, 32′ so stops 44, 44′ contact adjustable blocks 47, 47′ at the tops of stop guide slots 45, 45, the roller cam of arm 28 and slot 30 (
Positions of adjustable blocks 47, 47′ are selected for a cutoff so the roller cam of arm 28 and roller cam 100 of arm 28′ are positioned to contact the respective lower faces 30b, 30b′ when blanket cylinder supports 16, 16′ are moved toward plate cylinder supports 14, 14′ by impression cylinder supports 18, 18′. To ensure a desired printing arrangement, positions of adjustable blocks 47, 47′ are set so a nip pressure between plate cylinder 154 and blanket cylinder 156 is optimum when the lower faces of slots in blanket cylinder supports 16, 16′ are moved into contact with rollers of arms 28, 28′ by impression cylinder supports 18, 18′. In a preferred embodiment, arms 28, 28′ are not moved by the contact between rollers of arms 28, 28′ and lower faces 30b, 30b′. In order to set the proper positioning of impression cylinder 58 with respect to blanket cylinder 156, the position of cam 38 (
In other embodiments, plate cylinder supports 14, 14′ may be rotatably fixed to frame 12 and the position of plate cylinder supports 14, 14′ may be adjusted during cutoff changes.
In an alternative embodiment, variable cutoff printing unit 50 may be a perfecting printing unit that includes two plate cylinders and two blanket cylinders for printing on both sides of a web passing between the two blanket cylinders.
In a preferred embodiment, removable sleeves may be used in printing unit 50 to allow printing unit 50 accommodate printing plates and printing blankets of varying cutoff lengths. Plate cylinders supported by plate cylinder supports 14, 14′ and blanket cylinders supported by blanket cylinder supports 16, 16′ may each include a base cylinder or mandrel that is held at both axial end by the respective supports 14, 14′ or 16, 16′, a sleeve that is slid over the outer surface of the mandrel and a plate or blanket that is wrapped around or slid over the sleeve (i.e., sleeves are similar to the sleeves described in incorporated by reference U.S. Pat. No. 5,813,336). For example, during a cutoff change, at work side 10b, blanket cylinder support 16″ is uncoupled from and swung away from the work side end of a blanket cylinder mandrel. A blanket cylinder sleeve mounted on the blanket cylinder mandrel is then slid off of the blanket cylinder mandrel. A blanket mounted on the blanket cylinder sleeve may be removed before or after the blanket cylinder sleeve is slid off of the blanket cylinder mandrel. A different blanket cylinder sleeve having a larger or small outer circumference may then be mounted on the blanket cylinder mandrel. A new blanket may be mounted on the different blanket cylinder sleeve before or after the different blanket cylinder sleeve is slid onto the blanket cylinder mandrel. Removal and replacement of plate cylinders during cutoff changes may occur in the same manner, but with printing plates being mounted on the sleeves instead of blankets. Also, the blanket and plate cylinder mandrels may include holes formed in the outer surfaces thereof so pressurized air may be supplied internally to the mandrels and flow out of the holes to pneumatically mount and remove the sleeves from the respective mandrels. The blanket and plate cylinder mandrels may also include beveled ends on the work side thereof to facilitate the sliding of the sleeves onto the respective mandrel. The holes in the mandrels and the beveled ends, and the elasticity of the sleeves, allow sleeves that have inner circumferences that are slightly smaller than the outer circumferences of the mandrels to be mounted on the mandrels. After a sleeve is slid onto a respective mandrel, the supply of air to the mandrel is stopped and the sleeve is snugly held in place on the mandrel.
a and 5b show axial views of blanket cylinders 56, 156 according to a preferred embodiment of the present invention. As shown 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.
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| Number | Date | Country | |
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| 20120012017 A1 | Jan 2012 | US |
