US3785287A

US3785287A - Sheet interrupter

Info

Publication number: US3785287A
Application number: US00249944A
Authority: US
Inventors: H Dahlgren
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-06-17
Filing date: 1972-05-03
Publication date: 1974-01-15
Anticipated expiration: 1991-01-15

Abstract

Sheet interrupter means for a sheet-fed printing press wherein upper and lower printing cylinders are supported by eccentric bearings permitting simultaneous actuation of the upper and lower cylinders between printing and ''''off-impression'''' positions. A throw-off cylinder actuates a series of links to rotate the eccentric bearings.

Description

U I Unlted States Patent 11 1 1111 3,785,287 Dahlgren Jan. 15, 1974 SHEET INTERRUPTER 3,527,165 9/1970 Harless .1 101 143 2,911,907 11/1959 Davidson 101/137 [76] Invent Dahlgren, 726 Regal 3,477,367 11/1969 Richards 101/137 Dallas, 75247 3,473,468 10/1969 Vandeman et a1 101/137 3, Huck 1211 Appl' 249944 Primary Examiner-Robert E. Pulfrey Rd d U S A li ti D Assistant ExaminerE. M. Coven [63] Continuation-impart of Ser. No. 737,521, June 17, Atmmey Howard Moore et 1968, Pat. No. 3,664,261.

. [57] ABSTRACT [52] US. Cl 101/247, 101/137, 101/184 [51] Int. Cl B411 13/24 Sheet mtermpter means for a Sheet'fed prmtmg press 58 Field of Search 101/137 218 247 wherein "PPer and Priming cylinders are 101 /229 ported by eccentricbearings permitting simultaneous actuation of the upper and lower cylinders between [56], References Cited printing and off-impression positions. A throw-off 1 cylinder actuates a series of links to rotate the eccen- UNITED STATES PATENTS trig bearings. 2,753,798 7/1956 Babst 101/232 3,664,261 5/l972 5 Claims, 34 Drawing Figures Dahlgren 101/177 PATENTEU JAN 1 5 I974 SHEET UHF 18 PMENIEUJM 15 m4 SHIN 02 (1F 18 1 mm a Wkll.

amaze? PAIENIEUJM 15 m4 sum 03UF 18 PATENTEDJAI 15 B74 3.785.287 SHEET OSUF 18 JZHIM PATENTEDJAN 1 5 m4 785.287

sum as or 18 web leek 209 @OIZZH PATENTEUJAN 15 m4 SHEET OSUF 18 PATENTEDJAHSISM 3.785 287 saw 090? 1a i l "I M MN PATENTED JAN 15 I974 sum 12 or 18 PATENTED AN 1 5 I974 SHEEI 1% 0F 18 JAM-155374 3.785287 PMENTED sum 170F 18 PATENTEDJAI 15 m4 SHEET 180F 18 SHEET INTERRUPTER CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending US. Pat. application Ser. No. 737,521, filed June 17, 1968, now US. Pat. No. 3,664,261 entitled STRAIGHT FEED PRESS.

BACKGROUND OF THE INVENTION No significant advances have been made presenting new concepts in sheet-fed printing systems for decades. Printing systems designed for the sheet-fed printer are basically the same and allow printing on one side of the sheet at a time, requiring sheets to be turned over and rerouted through the press for single or multi-color perfecting. Sheets are progressively and meticulously transferred in serpentine fashion about transfer and impression cylinders and hopefully registered from one cylinder to another and from one printing unit to another until finally they emerge as a printed product; Printing units must be synchronized for color register through numerous drive and idler gears and consequently presses are extremely complex, massive units which are very expensive to manufacture because of numerous transfer and printing cylinders and mechanisms related thereto.

One or two color sheet-fed perfectors have been developed heretofore. However, these machines were specifically designed for specific jobs, such as mass production of paperback books, and are totally unsuitable for high speed production of four-color process printing on both sides of the paper.

Heretofore no commercially successful sheet-fed press had the capability of printing on two sides of a sheet in as many as four colors by passing the paper through the press one time.

It is the common and accepted practice in the printing industry to run a sheet to be printed through the sheet-fed press a multiplicity of times to attain multicolor printing on two sides of a sheet. After each pass of the sheet through the press, the plates must be changed and the press made ready for the next pass to apply other colors or to print on the back of the sheet. It is readily apparent to those skilled in the printing art that a considerable amount of time is spent making sheet-fed presses ready to print and in attaining proper registry of the numerous components of the press.

In a typical four-color one-side printing press a sheet delivered from the feeder is caught by the gripper bars of a first transfer cylinder. The sheet is folded around the transfer cylinder and carried to the grippers on the first impression cylinder where the grippers of the transfer cylinder release the paper and it is caught by the grippers of the impression cylinder. The grippers on the impression cylinder rotate the paper into contact with the blanket cylinder where printing is accomplished in one color on one side of the sheet. When the grippers on the impression cylinder release the sheet, grippers on a second transfer cylinder grasp the sheet, causing the printed surface to be in contact with the transfer cylinder while it is rotated to the grippers of a second impression cylinder. The grippers of the second transfer cylinder release the sheet as it is caught by the grippers of the second impression cylinder which rotates the sheet into contact with a second blanket where a second color is applied to the same side of the sheet. Grippers on a third transfer roller catch the sheet as it is released by the grippers of the second impression cylinder and the printed surface is again brought into contact with a transfer cylinder while it is being delivered to the grippers of a third impression cylinder. This process is continued until the sheet passes to delivery. When one side of the sheet is completed, the press is replated, the sheets are turned and re-fed through the press to print the other side of the sheet.

Virtually all sheet-fed printing presses heretofore developed have the characteristics of feeding the sheet serpentine fashion through the press while the grippers associated with each cylinder catch the sheet as it is being released by the grippers of the previous cylinder.

One of the major problems encountered by the printing industry lies in synchronizing the various cylinders whereby the sheet will be grasped and released at the proper moment for maintaining registry between the cylinders of successive towers so that colors do not' overlap or separate.

Chains have been used in the past with limited success to transfer sheets from one printing station to another. However, grippers supported by the chain were positively indexed to the printing station cylinders in an attempt to regain register which was periodically lost between printing stations.

A chain has inherent limitations as a smooth transfer media because chordal motion of the links limit smooth flow; linear deformation of the chain results from numerous pivot joints. Lubrication requirements at joints, to help prevent wear, noise, shock and vibration, present maintenance problems.

The gripper and chain transfer media could not, by itself, register the sheet between printing stations, even with the chain travelling precisely at cylinder speeds. As a compromise, grippers had to be loosely supported on the chain, moved from normal position, and indexed to printing station cylinders prior to actual sheet transfer at the cylinder. As soon as sheet transfer was accomplished and the gripper became separated from index with the cylinder, the gripper jumped or jerked back into its normal relation with the chain.

In the transfer system employed and disclosed herein, there is no contact between tape directed gripper bars and the printing cylinders thereby eliminating shock, vibration, wear, noise, mis-register and other apparent problems accompanied by chain supported grippers being indexed to cylinders. The printing cylinders are entirely independent of the sheet transfer mechanism and vice versa except for speed synchronization of cylinder surface speed with that of the tape.

Another problem has been the offsetting of wet ink on transfer cylinders from the freshly printed surface on the paper and consequently back on to the next sheet that is passed through the press. Heretofore, presses with a multiplicity of towers for applying more than one color of ink to the sheet were driven by a common drive through a complex gear train or through long shafts which have inherent distortion thereby increasing the problem of synchronizing components of the press thereby making precision registry more difficult.

Typical four-color one-side printing presses have an average of about 20 cylinders including the plate cylinders, blanket cylinders, impression cylinders, transfer cylinders and skeleton wheels.

Claims

1. In a sheet fed printing press, a feeder station; a delivery station; at least one cylinder support, including spaced side members intermediate the feeder and delivery stations; a printing cylinder journaled between the side members; an impression cylinder adjacent the printing cylinder, at least one of said cylinders having a gap formed therein; throw-off means secured to said printing cylinder and to said impression cylinder, said throw-off means being movably secured to the side members; means to rotate the said cylinders; means to apply ink to the printing cylinder; flexible conveyors movably extending along each side of the press from the feeder station to the delivery station; spaced elongated sheet engaging means extending between the conveyors and movable from the feeder station to the delivery station, said sheet engaging means being adapted to engage a sheet at the feeder station and continuously convey same between the surfaces of the printing and impression cylinders to the delivery station; means to secure the sheet engaging means to the flexible conveyors adjacent ends of the sheet engaging means; means to synchronize the rotation of the cylinders and the sheet engaging means to cause the gap and the sheet engaging means to be simultaneously moved into coinciding relationship relative to each other as the cylinders rotate, the sheet engaging means being spaced to enter the gap and move between the printing and impression cylinders in non-engaging relationship therewith; and actuating means to move the throw-off means to move the printing cylinder and the impression cylinder toward and away from a sheet moved therebetween by said sheet engaging means.

2. The combination called for in claim 1 wherein the throw-off means comprises, upper and lower bearings having outer surfaces eccentric to walls of a bore extending therethrough, ends of said printing cylinder and said impression cylinder being rotatably supported in the bores; and wherein said actuating means comprises, means secured to each of said upper and lower bearings arranged to rotate the bearings to move the printing and impression cylinders.

3. In a sheet fed printing press, a feeder station; a delivery station; at least one cylinder support, including spaced side members intermediate the feeder station and the delivery station; throw-off means movably secured to each of said side frames; a printing cylinder rotatably journaled in said throw-off means; an impression cylinder rotatably journaled in said throw-off means adjacent the printing cylinder, at least one of said cylinders having a gap formed therein and extending longitudinally thereof to allow passage of a gripper member between said cylinders; means to apply ink to the printing cylinder; continuous flexible sheet transfer means movably extending from the feeder station to the delivery station; means to drive the sheet transfer means at a preselected constant speed; gripper members carried by the sheet transfer means adapted to receive and grip the edge of the sheet at the feeder station and continuously convey same to the delivery station; carrier guide means adjacent opposite sides of the press to direct the gripper meMbers along a substantially straight path between opposite ends of the press; power transmission means to rotate said cylinders at a preselected constant speed; synchronizing means secured to the power transmission means and to the means to drive the sheet transfer means to cause the sheet transfer means and the printing cylinder to move in a selected unchanging speed relationship; and actuating means secured relative to at least one of the side frames to actuate the throw-off means from an off-impression position to an on-impression position wherein each of said printing cylinder and said impression cylinder is moved to engage a sheet carried by said gripper members positioned between the printing cylinder and the impression cylinder.

4. A method of printing comprising the steps of: positioning the leading edge of a sheet in a gripper element; moving the gripper element along a substantially straight path toward, through and away from a plurality of printing stations whereby the sheet when passing between adjacent cylinders in each printing station is maintained substantially in line contact with the cylinders; rotating first and second throw-off eccentric bearings having printing and impression cylinders mounted therein such that printing and impression cylinders are simultaneously moved into engagement with opposite sides of the sheet; and disengaging the leading edge of the sheet from the gripper element after the sheet has been moved through each of the printing stations.

5. The method of claim 4 wherein the step of moving the gripper element comprises, rotating endless flexible conveyors having a gripper element extending therebetween; and with the addition of step of synchronizing movement of the conveyors with movement of surfaces of the printing and impression cylinders.