US2986085A

US2986085A - Printing cylinders for rotary web presses

Info

Publication number: US2986085A
Application number: US805831A
Authority: US
Inventors: Thomas H Johnson
Original assignee: Cottrell Co
Current assignee: Harris Graphics Corp; Cottrell Co
Priority date: 1959-04-13
Filing date: 1959-04-13
Publication date: 1961-05-30
Anticipated expiration: 1978-05-30

Description

May 30, 1961 T. H. JOHNSON PRINTING CYLINDERS FOR ROTARY WEB PRESSES Filed April 13, 1959 2 Sheets-Sheet 1 INVENTOR 73'0" A. V0003.

Mr-M

h, ATTORNEY} y 1961 T. H. JOHNSON 2,986,085

PRINTING CYLINDERS FOR ROTARY WEB PRESSES Filed April 15, 1959 2 Sheets-Sheet 2 INVENTOR m ,9. @mvsa @ATTORNEY;

United States Patent PRINTING CYLINDERS FOR ROTARY WEB PRESSES Thomas H. Johnson, Westerly, R.I., assignor to The Cottrell Company, Westerly, KL, a corporation of Delaware i Filed Apr. 13, 1959, Ser. No. 805,831

8 Claims. c .101-1'17 It is universally true in all web printing presses that control of the web is essential in order to obtain accurate registry for satisfactory printing.

Where there are one or more printing units in a press, the paper web to be printed runs progressively, from the first to the last unit, and; at each unit,'va1-ious colors are applied to the paper. Such colors are arranged'so that after the final ink application, the paper has a'finished illustration or picture. In'the build-up of such pictures, perfect paper web register is needed, so that' all colors match the final result as accurately as were the individual colors prior to their color separation.

In order to properly-control a paper web, a certain amount of even tension or pull must be applied to the web.

On a web offset press, this latter control would be relatively easy if it were not for the gaps in the cylinder surface. These gaps are necessary for the accommodation of apparatus holding printing blankets to the cylinder.

It will be noted that on the type ofpress described; i.e., in which each blanket cylinder acts'in adual capacity, such as transfer and impression cylinder to the other when the paper is being printed between the co-acting cylinders, good tension control can be maintained. At the point where the gaps coincide as is customary in presently existing structures, the web tension control may bepartially or wholly lost due to the width of the coinciding gaps and their relation to the diameter of the cylinder. The larger the diameter of the cylinder the less aggravated is the problem of the coincidence of the gaps.

For many years partial solutions to the problem of web control where co-acting impression cylinder gaps coincide during the printing operation have been attempted by variations in the path of web travel and the preciselocation of the axes of the plate cylinders with relation to the impression cylinders to cause the web to partially wrap on one or both of the coacting blanket impression cylinders. This partial wrap of the web has heretofore been caused to take place on the incoming side of one 'impression cylinder and the outgoing side of the other impression cylinder or merely on the outgoing side of an impression cylinder. Web leads are also well known in which there is a partial wrap of theweb on both the incoming-and outgoing side of an impression cylinder.

I have solved the problem of web control by a novel construction, the object of which, is to control the web in its course through the printing unit or units primarily by an arran'gementof the coacting blanket cylinders so that the cylinder gaps noted above, whichare provided for elements clamping the blanket to the'cylinder, 'do" not coincide during the printing operation, thereby eliminating the necessity for a particular web feed angle to or from said blanket cylinders.

A further object of my invention is to provide a noncoincidence of the impression cylinder gaps by adjusting their cylinders so that the gaps do 'not"coincide during the rotation of any two coacting impression cylinders by staggering these gaps 180 with relation to each other. This is possible on presses where the cylinders are large A further object of my invention is to provide a press of the type described in which the impression cylinder gaps are arranged in staggeredrelation so that they never coincide.

A further object of my invention is to correlate the gaps on coacting blanket cylinders in order to reduce the possibility of failures in web control by practically eliminating the opportunity'for a lessening in web tension which may occur on the coincidence of the impression cylinder gaps which normally occurs in prior art structures.

A further object of my invention is to eliminate the necessity for imparting any particular angle to the common vertical axis of either the plate or impression cylinder axes of the respective units.

It is' a further object of my invention to minimize the problem caused by the gaps in the coacting impression cylinders during the printing operation by the insertion in said gaps of a removable filler piece adaped to cause the web to contact the circumference of the coacting web impression cylinder and thus substantially eliminate the web tension control problem caused by the aforementioned gaps or the rotation of any gap against any portion of a web'adjacent an impression cylinder surface.

It will be understood that, depending upon the finished product to be produced, it will be possible to locate the gaps around a cylinder radially at angles of 45 or depending upon whether eight or four finished products are to be produced from said cylinder. Broadly, my invention comprises a rotary printing press including at least one unit comprising a plurality of coacting impression cylinders, plate cylinders coacting therewith, and circumferential gaps in said impression cylinder, the parts being so constructed and arranged that the impression cylinder gaps do not coincide during the blanket cylinder gaps coincide during the printing'oPera tion and the web is momentarily not under adequate control} Fig. 2 represents diagrammatically in detail sectional side elevation aprinting' press unit constructed so'thatj the impression cylinder gaps are apart to prevent coincidence thereof during the printing operation;

Fig. 3 represents diagrammatically the arrangement wherein coacting blanket cylinders are arranged to print one web passed therebetween at right angles to the of said'cylinders, the cylinders'being located one directly over the other;

Fig. 4 represents a printing unit in which the axes of plate cylinders are invertical alignment and theblan ket cylinders are set at an angle 'toeach other, the incoming web path'being at right angles" to the axes of the blanket'cylinders;

Fig. 5 represents a modified form of my invention showing g p provided with a filler piece;

'Fig. 6repres'ents diagrammatically a side elevation of a I in the drawing, it"will be assumed that the respective print ing units are operatively'mounted in a printing press frame ow of ual ttu t onaad h t het avelina webis passed from a web supply roll to and through successive printing units by any well known or approved means (not shown). The means for driving the several '1 units of the press in order to print the web in colors on at least one side are well known in the art and form no part of my invention.

Reference numerals 1 and 2 designate coacting rotary blanket or impression cylinders located to run in normal printing contact with each other. Plate cylinders denoted by 3 and 4, are arranged to contact cylinders 1 and 2 and rotate in surface contact therewith to transfer the subject matter thereto for application to the traveling web, it being understood that each impression cylinder acts as the impression cylinder for its coacting blanket or impression cylinder.

The usual blankets for cylinders '1 and 2 are designated by the

numerals

5 and 6 and are tensioned across the surfaces of said cylinders 1 and 2 by the

usual clamps

7, 8 and 9, 10 located in

circumferential gaps

13, 14 on cylinders 1 and 2 respectively. The usual tensioning bars 11 and 12 are provided in each blanket cylinder for suitably holding the blankets to their cylinders.

The paper web which normally travels in an incoming path tangent to the two coacting blanket cylinders 1 and 2 at their point of printing contact is denoted by W.

As is illustrated in Figs. 2, 3 and 4, it will be seen that at no time during the concurrent rotation of cylinders 1 and 2 in printing contact with the web W does any blanket cylinder gap coincide with any other blanket cylinder gap whereby the problem of web tension control caused by blanket cylinder gap coincidence is diminished by at least one half. This non-coincidence of gaps is inherent also in the blanket cylinder arrangements according to my invention in which each blanket cylinder may have a plurality of gaps when the cylinders are adapted for the production of four or eight similar products on each complete rotation of the blanket cylinder. When a gap reaches the position with respect to the web where the latter is pinched between coacting blanket cylinders, the gap will always be opposed by an unbroken cylinder surface section. Additional web control is provided by the use of a gap filler piece now about to be described.

Fig. 5 of the drawings illustrates a blanket cylinder gap 13 provided with a removable resilient filler piece 15 which is normally both compressible and extensible for insertion in the

gaps

13, 14, or similar gaps. The filler element may be formed from sponge rubber, plastic or other suitable material having the desired characteristics of flexibility and resiliency and, as clearly illustrated, substantially fills the cylinder gap and extends slightly beyond the circumference of the cylinder for purposes to be more fully described below. It is contemplated that the inherent characteristics of the filler will be suificient to hold it in place against the sides of the gap without the necessity for additional mechanical securing means or the application of adhesive, although under certain conditions, either of these two aids might be necessary or desirable. The web contacting surface of the insert may be of similar frictional qualities as its adjoining cylinder surfaces in order to insure substantially continuous web contact without substantial change in web tension as the web passes between the gap filler and an unbroken section of blanket cylinder surface during the printing operation.

It will be noted from the foregoing that particular cylinder arrangements as to angular displacement of same is neither essential nor important to the present invention which is functional with the web lead tangent to the coacting impression cylinders, since the problem of Web control caused by gap coincidence during rotation of the cylinders is not present in my structure. However, if for any reason, such as servicing of the respective units or any cylinder thereof, it is desired to place successive units in different horizontal planes, this may be done without detracting from the efiicient operation of a printing press constructed according to my invention as the partial wrap of the web on the surface of an impression cylinder caused by any such arrangement has been well known in the art for many years.

Since it is evident that modifications can be made in the form, construction, and arrangements of the several elements herein described, I do not intend to be limited thereto except as set forth in the appended claims.

What I claim is:

1. In a rotary web printing press, a plurality of printing units for successively printing on a web, said units comprising coacting impression cylinders, plate cylinders located for surface contact with said impression cylinders for placing transferrable matter thereon, gaps in said impression cylinders for receiving impression cylinder blanket retaining means therein, and a web supply, the impression cylinder being in surface contact with a web passed therebetween so that an impression cylinder gap normally opposes an unbroken cylinder surface section during the web passage between said cylinders.

2. In a rotary offset web printing press, a plurality of printing units for successively printing on at least one side of a traveling web, said units comprising coacting rotatable impression cylinders in rolling surface contact with each other, plate cylinders located for surface contact with said impression cylinders for applying transferrable matter thereto, and gaps in said impression cylinders for receiving impression cylinder blanket retaining means therein whereby each impression cylinder gap opposes an unbroken impression cylinder surface section during the rotation of the impression cylinder.

3. A structure according to claim 2 in which each impression cylinder is provided with a plurality of spaced gaps.

4. A structure according to claim 2 in which the incoming web is fed in a path perpendicular to the vertical axes of the coacting impression cylinders.

5. A structure according to claim 1 including removable means for filling each cylinder gap to a point slightly above the circumferential surface of its impression cylinder.

6. In a rotary web printing press, a plurality of printing units for successively printing on a web, said units comprising coacting impression cylinders, plate cylinders located for surface contact with said impression cylinders for placing transferrable matter thereon, gaps in said impression cylinders for receiving impression cylinder blanket retaining means therein, removable means for filling each cylinder gap to a point slightly above the circumferential surface of its impression cylinder, and a web supply, the impression cylinders being in surface contact with a web passed therebetween so that an impression cylinder gap normally opposes an unbroken cylinder surface section during the web passage between said cylinders.

7. A structure according to claim 6 in which each means for filling a gap contacts a web surface opposite an unbroken section of the impression cylinder surface on the opposite side of the web from said filling means.

8. A structure according to claim 6 in which the means for filling each gap comprises an elongated resilient filler which is both compressible and extensible.

References Cited in the file of this patent UNITED STATES PATENTS 501,752 Wicht July 18, 1893 2,680,404 Royer June 8, 1954 2,821,134 Brodie Ian. 28, 1958 FOREIGN PATENTS 363,464 7 Great Britain Dec. 24, 1931 367,436 Great Britain Feb. 22, 1932