US1471895A

US1471895A - Method of and means for preparing cylinders of offset printing machines

Info

Publication number: US1471895A
Application number: US259420A
Authority: US
Inventors: William C Huebner
Original assignee: Individual
Current assignee: Individual
Priority date: 1918-10-23
Filing date: 1918-10-23
Publication date: 1923-10-23
Anticipated expiration: 1940-10-23

Description

Get. 23 1923. Y 1,471,895

W. c. HUEBNER METHOD OF AND MEANS FOR PREPARING CYLINDERS OF OFF-SET PRINTING MACHINES Filed Dirt. 25 1918 enemas on. as, ieaa unrra stars enses arser arrest,

7 WILLIAM C. HUEBNER, 01E BUFFkLO, NEW YO.

' mnrnon or AND means FOR PREPARING crztrnnnns or eraser rnrrrrrne momma.

hpplication flled October 23, 1191s. serial Ho. 259,420.

To all whom it may concern.-

Be it known that 1, WILLIAM C. HUEBNER, a citizen of the United States, residing at Buffalo, in the county of Erie and Stateof 5 New York, have invented a new and useful Improvement in Methods of and Means for Preparing Cylinders of Offset Printing Machines, of which the following is a specification.

This invention relates to off-set printing presses and more particularly to the relative .proportioning and method of building up the cylinders of the same in such a manner as to insure uniform and accurate printing and to avoid an increase in the size of the dots, lines or grains which constitute the image and the formation of streaks -or smears when printed upon the paper or 'other print-receiving sheets.

It has been found that at certain times an oil-set printing press will print in such a manner that the dots, lines or grains are of enlarged size, thus producing a heavier impression than is produced from the same plate in a proof press. The cause of this has not been known and was generally attributed to the rubber transfer blanket upon which the ink is transferred from the printing plate, it being thought that the contact between the transfer blanket and the paper or other material presses out the ink so as to increase the size of the dots, lines or other marks which form the image, Various means have been employed for preventing this heaviness in the prints; for

example, the dots, lines or grains constituting the image on the plates have been made smaller, but this resulted in producing such a light print on the-proof press that the finished proofs were rejected by customers, also acids have been used to etch the plates and reduce the size of the dots, etc, on the press plates. This, however, spoiled the plates and did not produce the desired results. Another defect in prezees of this kind is that at times the prints have streaks or lines of slurring, extending across the print, caused by the periodical enlarging of the dots, lines or grains, the remaining portions of the printing being fairly well done. These defects inthe press were only noticed at certain times and it frequently happens that the same press will produce a first class job while the next job is so defective as to be useless.

off-set printing press from a plate which produces good proofs on the proof press is due to the fact that the peripheral speeds of the surface of the cylinders of the press are not always the same, and that a slight difierence in the peripheral speeds of these cylinders causes a considerable enlargement of the dots, lines or grains, dueto the draggmg of the surface of one cylinder relatively to the surface of the other and to the fact that in o fi-set printing presses as now constructed, difi'erences in the thickness of the paper and in the printing plate are frequently compensated for in changing the centers of the cylinders re atively to each other. lhis causes the ars connecting the cylinders to move slig tly out of proper mesh, so that the back lash in the gears plus the slight variation of cylinder peripheralspeeds will spoil the prints.

Une object of this invention is to produce an ofi-set printing press and method of building up the cylinders thereof, such that the operator will be readily enabled to adapt the press for any variations in the thickness of the paper or other material to be printed,

in the plates and in the off-set printing blanket without changing the relative surface speeds of the cylinders, and without necessitating the changing of the working or printing centers of the cylinders;

In the accompanying drawing:

Thefigure is a sectional view of the three cylinders of an off-set printing press embodying the invention.

A represents the printing plate cylinder which is provided with the usual or any suitable means a forsecuring a printing plate a to the periphery of the cylinder. B represents the printing blanket cylinder which is also provided with the usual or any suitable means I) for securing the usual rubber or yielding blanket b on the cylinder, and C represents the impression cylinder which is preferably provided with a yielding impression cylinder blanket 0 which is suitably secured on the cylinder, and with paper gripping devices 0" of usual or suitable construction by means of which a sheet of paper or other material Dto be printed is held on the cylinder. The

cylinders are caused to turn simultaneously arrows, by intermeshing gears (not shown) at their ends. All of these parts have heretofore been used in off-set printing machines and, of themselves constitute no part of this invention.

In order to prevent differential movement between the peripheries of the cylinders, theoutside or overall diameters of the cylinders, including'the plates, blankets, printreceiving sheets or other parts mountedthereon, must always be the same. For this purpose the cylinders proper are all made of a diameter smaller than the pitch diameter of the earsconnecting the cylinders, which pitch iameter in presses having their cylinders geared together is the same as the overall diameter of the cylinders, and underlays of any suitable kind are placed underneath theprinting plate, transfer blanket or impression cylinder blanket, or. print- "receiving sheet, so that the diameters of all or print-receiving surfaces of the printin of these cylin ers will be the same as the pitch diameter of the gears connecting the cylinders. The pitch diameters'of the gears are indicated by the lines A A and A respectively, and the, printing or print-receiving surfaces of the several cylinders are indicated by the broken linesA". This may be accomplished in the case of the printing plate cylinder in the following manner:

The printing plates for a given type of off-set presses usually are not more than .014 of an inch ,in thickness but in order to-be sure of accommodating even thicker plates up to say1020, of an inch, the printing plate cylinder is preferably made of a diameter of about .040 of aninch less than the itch diameter A of the gear at its end, so t at the cylinder can accommodate a printing plate of .020 of an inch'thickness. If the printing plate is less than .020 ofan inch in thickness, an underlay E of any suitable material is used which is of such thickness that the combined thickness E of the printing plate and underlay amounts to .020 of an inch. For example, if theprinting plate is .014: of an inch in thickness, then an underlay sheet of .006 of an inch in thickness is used.- This is desirable since afairly tough, heavy underlay sheet forthe average plates, is not so apt to tear or wrinkle as a thinner sheet. A plurality of underlay sheets of different thicknesses are therefore provided which can be used in connection with different printing, plates and in setting up themachine for a job, the thickness of the printing plate is first determined in any suitable way. The operator then consults the upper table of the chart shown in Fig. 2 and sees at once the thickness of the underlay necessary in connection with the printing plate. In the case of he printing blanket cylarissa sate for the minimum amount of depression in the yieldingblanket at the proper inklifting condition. If, for example, allowance is made for a blanket and underlay sheet of .075 of an inch in thickness the printing blanket cylinder is made .150 of an inch smaller in diameter than the pitch diameter A of the gear to which the printing plate cylinder is connected. The combined thickness F of the blanket I) and the underlay F for this 0 linder must in such case amount to .076 or .0 7 of an inch. After determining the thickness of the transfer blanket the operator employs the second table of the chart in Fig.2 and ascertains the thickness of the underlay in the same manner as described for the printing plate cylinder. r r

The diameter of the impression cylinder must be less than the pitch diameter A of the gear connected thereto by an amount suilicient to enable the cylinderto carry a printreceivin sheet 'D of the maximum thickness which may be used on the ress, and an underlay G and preferably a so an imression blanket c. The combined thickness ofthe print-receiving sheet or paper, blanket and underlay indicated on the third. table of the chart is .078 of an inch, this dimens'ion having been found satisfactory, as it avoids the use of very thin underlay .sheets. When thicker pape'r'is used a thinner underlay is employed providedthe same impression blanket is used, and when the paper isthin a thicker impression blanket or underlay must be 'used,'s0 that the combined thickness of the paper, blanket and underlayi's always sufficient to bring the external diameter A of the cylinder and parts carried thereby up to .078 of an inch.

The dimensions given are only illustrative and are not intended in any way to limit the construction of printing presses of this kind under this invention. It is de sired, however, toprovide a series of under? 'lays of different thickness for each of the cylinders andby means of the table shown,

in Fig. 2 the printer, when he ascertains' the thickness of the printing plate, of: the printing and impression blankets and of the print-receiving paper can immediately determine the thickness of underlays which are requiredand' can readily build up his cylinders accordingly. Consequently the external diameters of the cylinders and parts mounted thereon are always the same, there- 12 by eliminating all rubbing or differential movement between the cylinders, and since it never becomes necessary ,to change the 1 distance between working or printing cen ters of the cylinders the gears always retill main in perfect mesh, so that streaks or lines in the-prints are avoided. ln this manner a correct reproduction is produced at all times with a uniform but minimum printing pressure and the re-etching of the printing plate or other objectionable practices forreducing the size of the dots, dashes and other parts constituting the image is avoided. r

I claim as my invention:

1. In an ofi-set printing machine, the

combination of a plurality of cylinders,

said cylinders having. equal gear pitch-line diameters and each of said cylinders having a peripheral diameter which is a known amount less than the pitch-line diameters, a printing plate secured on one of said cylinders of a known thickness less than the radial difference between its cylinder and the pitch-line thereof, and. an underlay placed between said cylinder and its printing plate and being of known thickness equal to the radial difference between the cylinder plus the thickness of the plate and said pitch-line, so that the combined thickness of said underlay and printing plate will give the external cylindrical surface of said printing plate a diameter equal to the pitch-line diameters.

2. In an off-set printing machine, the

qombination of a plurality of cylinders, said cylinders having equal gear pitch-line diameters and each of said cylinders having a peripheral diameter which is a known amount less than said pitch-line diameter, one of said cylinders carrying av printreceiving sheet of a known thikness less than the radial difference between the surface of said cylinder and the pitch-line thereof, and an underlay placed between said cylinder and the print receiving sheet, said underlay being of known thickness equal to the radial difi'erence between the cylinder plus the thickness of said print receiving sheet and the pitch-line thereof so that the combined thickness of said underlay and print receiving sheet will give the external cylindrical surface of said print receiving sheet a diameter equal to said pitch-line diameters.

3. In an off-set printing machine, the combination of a plate cylinder carrying a printing plate, an impression cylinder carrying a print receiving sheet, a blanket cylinder provided with a printing blanket which contacts with said plate and sheet, for

transferring-the impression from said plate to said print receiving sheet, said cylinders having equal gear pitch-line diameters and' each of said cylinders having a peripheral diameter which is a known amount less than said pitch-line diameters, said blanket being of a known thickness less than the radial difference between its cylinder and the pitch-line thereof, and an underlay between said blanket and its cylinder of known thickness equal to the radial difference between -the cylinder plus the thickness of the blanket and said pitch-line so that the combined thickness of said underlay and blanket will give the external cylindrical surface of said blanket a diameter equal to said pitch-line diameters.

-l. In an off-set printing machine, the combination of a plate cylinder carrying a printing plate, an impression cylinder carrying a print receiving sheet, a blanket support provided with a printing blanket which contacts with said plate and sheet for transferring the impression from said plate to said print receiving sheet, said cylinders having equal gear pitch-line diameters and each of said cylinders having a peripheral diameter which 'is a known amount less than said pitch-line diameters, said printing plate and print receiving sheet being of known thicknesses less than inder plus .the thickness of the plate and the witch-line thereof and the impression cylinder plus the thickness of the sheet and the pitch-line thereof so that the external surfaces of said plate and said sheet will be of equal diameters and said plate, blanket and sheet will all have equal surface speeds.

5. In an off-set printing machine, the combination of aplate cylinder carrying a printing plate, an impression cylinder carrying aprint receiving sheet, a blanket cylinder provided with a printing blan ket. which contacts with said plate and sheet for transferring the impression from said plate to said print receiving sheet, said cylinders having equal gear pitch-line diameters and each of said cylinders having a peripheral diameter which is a known amount less than its pitch-line diameter, said plate, print receiving sheet and blanket each being of a known thickness less than the radial difference between the respective cylinders and the pitch-lines, and an underlay betweeneach of said cylinders and the plate. blanket or sheet thereon, said underlays being of known thicknesses equal respectively to the radial differences between said respective cylinders plus the thickness of the plate, blanket or sheet thereon and said pitch-lines so that the external surfaces of said plate, blanket and sheet will all have equal diameters.

6. In an off-set printing machinefthe equal gear pitch-line diameters and each of said cylinders having a peripheral diameter which is a known amount less than said pitch-line diameters, and an underlay be-. tween each of said cylinders and the plate or blanket thereon, said underlays'being of known thicknesses'equal to the radial differences between the said cylinders plus the plate or. blanket and sheet thereon and pitch-lines so that the external surfaces of said plate, printing blan ket and'sheet'swill have equal diameters.

7. The herein described method of preparing cylinders of an oif-setprinting machine having a, cylinder with a printing plate, an impress on cylinder, and means with a printing blanket for transferring the impression from said plate to a print receiving sheet on the impression cylinder, which'method consists in employing cylinders having equal gear pitch-line diameters, and each cylinder having a peripheral diameter which is a known amount less than the pitch-line diameters, using a printing plate on the printing cylinder of known thickness less than the radial difference between the surface of the cylinder and the pitch line thereof and using a print receiving sheet of known thickness less than the radial difference between the surface of said impression cylinder and the pitch-line thereof, and placing underlays under the printing plate and print receiving sheet, said underlays being of known thicknesses and equal respectively to the radial differences between the printing plate cylinder plus the printing plate and the impres;

sion cylinder plus the print receiving sheet and their pitch-lines so that the externalsurfaces of said plate and said sheet will have-the samediameters and will travel at the same surface speed .as said printing blanket. r

8. The hereindescribed method of preparing cylinders of an off-set printing machine having a cylinder with'a printing plate, an vimpression cylinder and a cylinder with a printing blanket for transferring the impression from said plate to a print receiving sheet on theimpression cylinder,

which method consists in employing cylin- 7 der said printing plate, printing blanket and print receiving sheet underlays of known thicknesses respectively equal to the radial differences between the plate cylinder plus the thickness of its plate, blanket cylinder plus the thickness of its blanket and the impression cylinder plus the thickness of its sheet and their pitch-lines so that the contacting surfaces of the several cylinders will all have equal diameters and travel at equal surface speeds.

- 9. The herein" described method of preparing the cylinders of an oif-set printing machine having a cylinder with a printing plate, an impression cylinder and a cylinder with a printing blanket for transferring the impression from said plate to a print receiving sheet on theimpression cylinder, which method consists in employing cylinders having equal gear pitch-line diameters and each cylinder having a pcripheral, diameter which is a known amount less than said pitch-line diameters, using a printing plate, blanket and print receiving sheet of known thicknesses on saidcylinders, the thickness of said plate, blanket and sheet being less than the radial difference between the; radius of its-respective cylinder and the pitchdine thereof, and'placing under said plate blanket and print receiving sheet underlays of known thicknesses, the thicknesses of said underlays being equal respectively to the radial differences between their respective cylinders plus the thickness of its printing plate, blanket or print receiving sheet and the pitch-lines so that the contacting surfaces on the several cylinders will all travel at equal surface speeds and all have diameters equal to each other and to the pitch-line diameters of the gears connecting the cylinders.

Witness my hand this 19th day of October, 1918. I 1 I WILLIAM C. HUEBNER. Witnesses:

C. W. PARKER, A. L.