US3556006A

US3556006A - Rotary sheet transfer members having engageable toothed sectors in proximity to sheet grippers

Info

Publication number: US3556006A
Application number: US730546A
Authority: US
Inventors: Paolo Papa; Federico Cappetti
Original assignee: SOC NEBIOLO SpA
Current assignee: SOC NEBIOLO SpA
Priority date: 1967-10-14
Filing date: 1968-05-20
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19
Also published as: DE1761754C3; DE1761754B2; DE1761754A1; GB1237724A; FR1585752A; JPS5115442B1

Abstract

A printing press comprises a plurality of gripper carrying rotary impression and transfer cylinders play which paper sheet to be printed are transferred. Each cylinder has a pair of lateral discs and each disc has mounted thereon a toothed sector adapted to cooperate with the toothed sector mounted on one of the lateral discs of a cooperating cylinder during each step of exchange of a sheet. The sectors of each cooperating pairs thereof being preferably different in pitch radii and being so made as to have one pair of elements only, namely one tooth and a pair of teeth, respectively which intermesh without play during the said step of exchange. The remaining teeth having variable play during interengagement of the sectors, growing with the distance from the above said elements.

Description

Inventors Paolo Papa;

Federico Cappetti, Turin, Italy 730,546

May 20, 1968 Jan. 19, 1971 Societa Nebiolo S.p.A.

Turin, Italy Oct. 14, 1967 Italy No. 53353-A/67 Appl. No. Filed Patented Assignee Priority ROTARY SHEET TRANSFER MEMBERS HAVING ENGAGEABLE TOOTI-IED SECTORS IN PROXIMITY T0 SHEET GRIPPERS 9 Claims, 3 Drawing Figs.

US. Cl. 101/232, 101/248, 101/246, 74/440, 271/69 Int. Cl. ..Fl6h 55/18, B6511 5/12 Field 01 Search 101/248, 137, 142, 183, 217, 232, 246; 74/409,440; 271/69 References Cited UNITED STATES PATENTS 6/1906 Berry 101/248 1,498,653 6/1924 Harrold 101/248 2,767,652 10/1956 Dietrich et al.. 101/248 2,887,046 5/1959 Knops et al. 101/248 FOREIGN PATENTS 516,885 1/1931 Germany 101/248 1,124,053 2/1962 Germany 101/183 Primary ExaminerRobert E. Pulfrey Assistant ExaminerJ. Reed Fisher Attorney--Sughrue, Rothwell, Mion, Zinn and Macpeak ABSTRACT: A printing press comprises a plurality of gripper carrying rotary impression and transfer cylinders between which paper sheet to be printed is transferred. Each cylinder has a pair of lateral discs and each disc has mounted thereon a toothed sector adapted to cooperate with the toothed sector mounted on one of the lateral discs of a cooperating cylinder during each step of exchange of a sheet. The sectors of each cooperating pairs thereof being preferably different in pitch radii and being so made as to have one pair of elements only, namely one tooth and a pair of teeth, respectively which intermesh without play during the said step of exchange. The remaining teeth having variable play during interengagement of the sectors, growing with the distance from the above said elements.

SHEET 1 OF 3 PATENTED JAN 1 91971 mgmguqmzsmn 3,556,006

SHEET 2 OF 3 Fig.2

PATENT EU JAN] 9 {97! SHEET 3 OF 3 The invention relates to printing presses of the type wherein the paper sheets are transferred bet'ween a plurality of rotary members.

lt is known that more particularly in printing presses for multicolor sheets, comprising a plurality of components each including an impression cylinder an a number of transfer cylinders, all provided with grippers which mutually exchange the sheets being printed, the latter should be exchanged between one component and the next so as to be constantly presented to the various impression cylinders in the same position in order to successively print thevarious colors constantly at the predetermined positions or in register.

A condition for maintaining register is accurate retaining of the sheet by, the grippers on the various cylinders during withdrawal, transport and delivery to the next cylinder.

A further condition is a correct mutual positioning of the two sets of grippers effecting the exchange. Any offset from the mutual position of the grippers on one cylinder or between the grippers on the cylinderreceiving the sheet and the cylinder delivering the sheet, respectively, occuring during exchange, detrimentally affects quality of the register. l i

In order to. obviate this drawback it was proposed to provide in proximity to the grippers cooperating in exchange, in addition to conventional cylinder driving gears, a pair of structural members having conjugated profiles, or to provide on the cooperating driving gears pairs of toothed sectors fixedly secured thereto, or still to provide on the said gears toothed sectors one of which isrigidly fixed to a gearand the other is resiliently connected to the second gear.

All the above arrangements which merely aimed at taking up play between the sets of teeth in the gears rotating contiguous cylinders, do not solve the registerproblem, inasmuch as the above mentioned plays, though objectionable are neither alone nor by a major part responsible for register inaccuracies. It was ascertained that the latter are mainly due to vibrations and twist of the cylinders or other rotary members between which the sheets are exchanged during operation of the printing press.

An object of the invention is to'provide a rotary printing press having a plurality of rotary members between which the sheets are exchanged, wherein vibrations and torsional stressesv on these members so not lead to inaccuracies in register.

The invention provides to this effect on the lateral discs of the rotary members of the press carrying the grippers, pairs of toothed sectors adapted to cooperate by pairs during the exchange step, of a configuration such that during this step to the vibrations and/or torsional stresses of one rotary member there correspond similar vibrations and/or torsional stresses of its cooperating rotary member.

According to a preferred embodiment of the invention the sectors are shaped so that at the start and end of the meshing step of the sectors of each pair a maximum play exists between their respective teeth, which gradually decreases till it is annulled at their middle zone over an arc the length of which is selected in accordance with the period of time of the exchange step.

The sectors may conveniently have a modular and circular set of teeth and differ in pitch radii. The sector of the larger pitch radius is concentrically mounted on its respective rotary supporting member,the sector of smaller pitch radius being eccentrically mounted with respect to the axis of the otherrotary member cooperating with the former. v

Further characteristic'features and advantages of the invention will be understood from the appended description referring by way of example to an embodiment shown on the accompanying drawings, wherein:

H6. 1 is a diagrammatical side elevational view of a machine accordingto the invention comprising two printing members;

FIG. 2 is a sectional view on line II-Il of FIG. I on an enlarged scale; v FIG. '3 is a side view of a pair of cooperating sectors each mounted on one of the contiguous rotary members provided with grippers, between which the sheets are exchanged.

On the drawings, 1 and 2 denote the two printing elements forming a two-color' sheet printing press. Each element comprises an impression cylinder 3 cooperating with a rubber cylinder 4 which is in contact with a further cylinder 5 carrying a plate (not shown) which is engraved and inked in a I manner known per se..

Sheet transfer cylinder 6, 7, 8, respectively, are interposed between the impression cylinders 3 of the elements 1, 2, respectively. The impression cylinder of the element 2 receives sheets fromthe oscillating grippers diagrammatically denoted by 9, the impression cylinder 3 on the element 1 delivering the sheets to the outlet chain diagrammatically denoted by 10.

The impression cylinders 3 and transfer cylinders 6, 7 and 8 carry at their lateral discs lls, 11d and 12s, 12d, respectively (FIG. 2) toothed sectorsl3's, l3'd and 13s, I3d, respectively, the former only being visible in FIG. 1. The cylinders 3, 6, 7 and 8 are so positioned that the toothed sectors on contiguous cylinders cooperate together throughout the exchanges carried out by means of grippers 23, 24 (FIG. 3), in which the cylinders are involved.

As will be seen in FIG. 2, the cylinders are carried by shafts 14 rotatably 'mounted in supports 15 driven into the opposite sidewalls 16 of the machine frame. The shafts 14 of the cylinders 3, 8 are kept against axial displacement by known devices, not shown.

The cylinders are rotated through their driving gears 17 keyed to the ends of the shafts 14 extending beyond one of the sidewalls 16 and forming a kinematic chain leading to a driving motor for the machine (not shown).

The toothed sectors 13s and 13's, 13d and l3'd of each of the cooperating sector pairs such as the sectors mounted on the lateral discs of the cylinders 3, 8 respectively, though being both circular and modular, differ in pitch circles. As will be seen in FIG. 3, the sector 13's mounted on the lateral disc 11s of the impression cylinder 3 of the first element has its center situated on the rotational axis C of the cylinder 3, the sector 13: mounted on the lateral disc 12.: of the cylinder 8 having its center situated a distance e apart from the rotational axis C of the cylinder 8.

The sectors are provided with one pair only, of elements namely the tooth l8 and the teeth 19 which intermesh without play during the exchange of the sheets, the remaining teeth meshing with a'gradually variable play.

By this structure as cooperation of the two sectors starts gradually decreasing plays exist on the flanks of the consecutive teeth, and are annulled when the tooth 18 starts meshing in the hollow between the teeth 19, exactly at the region where the pitch circle of a sector is tangential to the pitch circle of the other sector. At the end of the exchange step the play between the teeth of the two sectors again gradually increases till full mutual disengagement of the sectors.

As further shown in FIG. 3, Rp and R'p are the radii of curvature of the pitch circles of the gears 17 keyed to shaft 14 carrying the cylinders 8 and 3, respectively; rp is the radius of the pitch circle of the tooth sector 13s; and P, and P, are the rotational axes of the grippers 24 and 23, respectively.

By the above-described structure the cooperation of the sectors takes place in the absence of shocks even at high rates of speed and any angular offset of the two cylinders between which exchange occurs is taken up in the absence of objectionable vibrations. The structure is. advantageous in simplicity of construction and assembly, inasmuch as the sectors are partsof modular, gears currently manufactured and their assembly on the lateral discs of the cylinders can be carried out without necessitating expensive apparatus and in a short time.

The sectors 13's and l3'd that are concentric with the axis of the cylinder 3 preferably are mounted on the cylinder 3 in such manner that their pitch circles are the same as the pitch circle of the driving gear 17 for the cylinder 3. Each of the other sectors 13s and 13d are so mounted on the cylinder 8 such that the tooth l8 accurately fits, substantially without clearance, into the hollow between the teeth 19 of the corresponding sector at the point of tangency of the sectors. This is accomplished by the

positioning pins

20 and 21 which engage the inner periphery of each of the sectors 13s and 13d, which may be locked in position by the locking screws shown in FIG. 3 or by any other suitable means. Each of the sectors 13s and 13d are adjustable relative to the

positioning pins

20 and 21 by providing holes (not shown) therein which are larger than the shanks of the locking screws. if the sectors 13s and 13d are to be positioned in spaced relation to the

pins

20 and 21, the spacing between each of the sectors and the pins should be substantially equal in order to properly orient the sectors on the cylinder 8.

We claim:

1. in printing press of the type comprising a plurality of rotary members between which a sheet to be printed is transferred, a gripper on each of said rotary members for retaining a sheet thereon when it is transferred thereto from another rotary member, a pair of lateral discs mounted on the sides of each rotary member, and a driving gear rotatable about the rotary axis of each rotary member and secured thereto in spaced relation therewith. the driving gears for cooperating rotary members being constantly intermeshed; the improvement comprising a curved toothed sector mounted on each of said lateral discs in proximity to the gripper on the corresponding rotary member. the pair of sectors mounted on the lateral discs of one rotary member being positioned gradually to engage and then disengage the pair of sectors mounted on the lateral discs of an adjacent rotary member as a sheet is being transferred from a gripper on said one rotary member to a gripper on said adjacent rotary member. the pitch circles of said pairs of sectors being tangential at the point at which a sheet is transferred from the gripper of said one rotary member to the gripper of said adjacent rotary member.

2. The printing press as claimed in the claim 1, wherein the sectors of said adjacent rotary member are of variable curvature with respect to the rotational axis of said adjacent rotary member.

3. The printing press of claim I wherein the pitch radii of the sectors of said one rotary member are larger than the pitch radii of the sectors of said adjacent rotary member, the sectors of said one rotary member being concentrically mounted on the lateral discs thereof, and the sectors of said adjacent rotary member being eccentrically mounted with respect to the axis of the lateral discs thereof.

4. The printing press of claim 1 wherein the pitch radii of the sectors of said one rotary member are equal to the radius of the driving gear therefor.

5. The printing press of claim 1 wherein the pitch radii of the sectors of said one rotary member are less than the radius of the driving gear therefor.

6. The printing press of claim 1 wherein the pitch circles of the sectors of said adjacent rotary member are tangential to the pitch circle of the driving gear for said one rotary member.

7. The printing press of claim 1 wherein each of the sectors of said adjacent rotary member has one tooth that is adapted to fit substantially without clearance between a pair of teeth of the corresponding sector of said one rotary member at the point at which a sheet is transferred from the gripper of said one rotary member to the gripper of said adjacent rotary member.

8. The printing press of claim 6 wherein the pitch circles of the sectors of said one rotary member are tangential to the pitch circle of the driving gear for said adjacent rotary member.

9. The printing press of claim 7 wherein the remaining teeth on each of said sectors of said adjacent rotary member are arranged symmetrically with respect to said one tooth and are adapted to gradually engage with clearance and then gradually disengage the teeth of the corresponding sectors on said one rotary member when said sectors on said one and said adjacent rotary members are engaged during the transfer of a sheet.

Claims

1. In printing press of the type comprising a plurality of rotary members between which a sheet to be printed is transferred, a gripper on each of said rotary members for retaining a sheet thereon when it is transferred thereto from another rotary member, a pair of lateral discs mounted on the sides of each rotary member, and a driving gear rotatable about the rotary axis of each rotary member and secured thereto in spaced relation therewith, the driving gears for cooperating rotary members being constantly intermeshed; the improvement comprising a curved toothed sector mounted on each of said lateral discs in proximity to the gripper on the corresponding rotary member, the pair of sectors mounted on the lateral discs of one rotary member being positioned gradually to engage and then disengage the pair of sectors mounted on the lateral discs of an adjacent rotary member as a sheet is being transferred from a gripper on said one rotary member to a gripper on said adjacent rotary member, the pitch circles of said pairs of sectors being tangential at the point at which a sheet is transfeRred from the gripper of said one rotary member to the gripper of said adjacent rotary member.

3. The printing press of claim 1 wherein the pitch radii of the sectors of said one rotary member are larger than the pitch radii of the sectors of said adjacent rotary member, the sectors of said one rotary member being concentrically mounted on the lateral discs thereof, and the sectors of said adjacent rotary member being eccentrically mounted with respect to the axis of the lateral discs thereof.