US2839992A

US2839992A - Offset printing machine

Info

Publication number: US2839992A
Application number: US546549A
Authority: US
Inventors: Lawrence H Morse
Original assignee: Multigraphics Inc
Current assignee: AB Dick Co
Priority date: 1955-11-14
Filing date: 1955-11-14
Publication date: 1958-06-24
Anticipated expiration: 1975-06-24

Description

June 24, 1958 L. H. MORSE 2,839,992

v OFFSET PRINTING MACHINE Filed Ndv. 14, 1955 5 Sheets-Sheet 1 IN VEN TOR. Z A wmwzzli finer:

June 24, 1958 L. H. MORSE OFFSET PRINTING MACHINE 5 Sheets-Sheet 2 Filed Nov. 14, 1955 INVENTOR. Z A WEE/V05 I2. flame 5521907? v/Z!&M

A'TIDIPIYEY/ June 24, 1958 L. H. MORSE OFFSET PRINTING MACHINE Filed Nov. 14, 1955 5 Sheets-Sheet 3 mmv TOR. Z A WIPLNCE f7. Hams BY 6041, 1 Z! flea June 24, 1958 L. H. MORSE 2,839,992

OFFSET PRINTING MACHINE Filed Nov. 14, 1955 I 5 Sheets-Sheet 4 mmvroa. LA wmsvm Iii/Y0 er:

BY afin/ ew J2 $m Errata/Er Filed Nov. 14, 1955 OFFSET PRINTING MACHINE 5 Sheets-Sheet 5 mmvron [A wtE/vc: H. Home 2,839,992 OFFSET PRTNTlNG MACHINE Application November 14, 1955, Serial No. 546,549

11 Claims. (Cl. 101-218) This invention is concerned with improvements in or relating to rotary offset printing machines having an offset cylinder disposed between a master printing plate cylinder and an impression cylinder to transfer an inked image formed on the master cylinder to a worksheet passed between the bite of the offset and impression cylinders.

In printing machines of the type with which the present invention is concerned, it is desirable to automatically separate the master impression cylinder from the offset cylinder consequent upon the absence of a worksheet in the bite of such cylinders, thereby avoiding the transfer of ink from the offset cylinder to the surface of the impression cylinder and from the latter to the under face of a subsequently fed worksheet. When such separation takes place it is desirable that the master cylinder be separated from the offset cylinder to avoid excessive transfer of ink from the master cylinder to the ofiset cylinder, to thus prevent an over inked imprint on a subsequently fed worksheet. It is also desirable that means be provided to enable a separation between the offset and impression cylinders to take place while contact between the master and offset cylinders is maintained, to thereby permit the building of proper inked image on the master and offset cylinders prior to the commencement of printing operations.

The general object of the present invention is to provide an improved rotary offset printing machine having printing cylinders so mounted as to permit the separation as above-mentioned, together with an improved mechanism which will act automatically consequent upon the absence of a worksheet to cause such separation, and a manually operable control to determine which cylinders will be separated.

According to the invention the master and impression cylinders are mounted to rotate about relatively fixed axes, while the ofiset cylinder is mounted for movement to any one of three positions, in one of which the offset cylinder coacts with both master and impression cylinders, in another of which the offset cylinder is separated from both master and impression cylinders, while in a third or intermediate position the offset cylinder coacts with the master cylinder but is separated from the impression cylinder.

The movement of the offset cylinder to the desired positions is accomplished by mounting it for rotation about an axis which is movable in a circular path, the center or axis of which is fixed relative to the axes of the master and impression cylinders, and by so positioning the axes relative to each other that the cylinders are in their normal printing positions with proper printing pressures established therebetween when a line extending between the fixed axes of the master cylinder and the circular path forms an angle of less than one hundred and eighty degrees with a line extending between the axes of the circular path and the impression cylinder and a smaller angle measured in the same direction with a line extending between the axes of the olfset cylinder and the circular path, while maintaining the distance between the axes of the impression and master cylinders greater than the sum of their radii and while maintaining the distance between the axes of the master cylinder and the circular path greater than the sum of the radii of the cir- United tates Patent cular path and oifset cylinder. Means are provided to move the axis of the oifset cylinder along the circular path from normal printing position and away from the impression cylinder to a position where the line passing through the axes of the offset cylinder and circular path forms the same angle with the first-mentioned line as it did in the normal printing position but measured in the opposite direction. In the latter position the offset cylinder coacts with the master cylinder in the same manner as when in its, normal printing position, but is separated from the impression cylinder. When it is desired to separate the offset cylinder from the master cylinder as well as from the impression cylinder, the axis of the offset. cylinder is moved in the same direction in the circular path to increase the last named angle and yet maintain the distance between the axes of the offset and impression cylinders greater than the sum of their radii.

To make the invention clearly understood, reference: will now be made to the accompanying drawings illus-- trating a practical embodiment of the invention and a diagrammatical illustration thereof.

In the drawings:

Figure 1 is a vertical sectional view taken through a rotary offset printing machine embodying the present in-- vention, the parts being illustrated in a normal printing position;

Figure 2 is a sectional view similar to Fig. l, but illustrating the parts in a position wherein the offset cylinder coacts with the master cylinder but is spaced from the: impression cylinder;

Figure 3 is a view similar to Figs. 1 and 2, illustrating: the offset cylinder separated from the master and impres sion cylinders;

Figure 4 is a fragmentary plan view of the machine shown in Figs. 1 to 3, partially broken away and the master cylinder removed to more clearly illustrate the mounting for the offset cylinder;

Figure 5 is a sectional detail, the plane of which is indicated by the line 55 on Fig. l; and

Figure 6 is a diagram illustrating the relation of the axes of the various cylinders relative to each other for diiferent positions of the offset cylinder.

Rotary offset printing machines are well known at the present time, hence only such parts thereof have been illustrated as is required to provide an understanding of, the present invention. Mechanisms such as the printing plate and offset blanket retainers, or clamps, as well as inking mechanisms, have been omitted. It is contemplated that the invention may be used in connection with rotary pl'anographic or lithographic printing machines which utilize an ink repellant applicator as well as an inking mechanism. As such applicators are well known, none will be described or illustrated. Other kell known mechanisms such as worksheet grippers, strippers, and ejectors have been but partially illustrated.

Referring now to the drawings in detail, it will be seen that the printing machine illustrated includes a pair of vertically extending side frame members 10 spaced apart by suitable cross frame members, not shown. A master cylinder 20, an offset cylinder 30, and an impression cylinder 40 are disposed between and supported by the frame members 10.

The master cylinder 20 is mounted for rotation about the axis of a shaft 22 carried by the frame members 10. The master cylinder may be rotatably mounted on such shaft or the shaft may be rotatably mounted in the frame members 10 as desired. In either case the axis of rotation of the cylinder is fixed relative to the frame members It). The impression cylinder 40 is similarly mounted for rotation about the axis of a shaft 42 which is supported by the frame members 10 in any wellknown manner. The axis of rotation of the impression cylinder, like that of the master cylinder 29 is fixed relative to the frame of the machine. It is to be understood that suitable adjustments may be provided to align these axes one with the other to permit regulation or adjustment of the distance therebetween, hence the term, fixed, when used in connection with the axes of these cylinders does not preclude the use of adjusting means, but merely means that during operation of the machine such axes are stationary relative to the movement of the axis of the rotation of the offset cylinder hereinafter to be described.

The master cylinder 20 has a printing plate 23 extending about its circumference. The plate may be secured to the cylinder in any well known manner, for instance, by clamps shown in Patent No. 1,968,849.

Either the impression cylinder or the offset cylinder 30 may be equipped with a suitable work sheet receiving or clamping mechanism to insure passage of the work sheet between the bite of the impression and offset cylinders. Likewise, a suitable work sheet ejector or stripper mechanism may be provided to insure discharge of the work sheet from the bite of such cylinders. Suitable mechanisms for such purposes are illustrated and described in detail in Patent t-ioned. For ease of illustration such mechanisms have been indicated as cooperating with the impression cylinder 40. As indicated the surface of the impression cylinder is provided with a gap 44- in which a paper receiving mechanism is mounted. This mechanism includes a series of axially spaced fingers 45 secured to a shaft 46 having its ends journaled in respective end walls 4-7 of the cylinder 40. The shaft 46 extends outwardly beyond one of the end walls and is provided on its outer end with a lever 48 carrying a cam roller d9 a ranged to coact with a stationary cam 50 secured to the adjacent frame member 16 by bolts 51. A spring 52 extending between a pin 53 carried by the shaft 46 and a pin 54 carried by the cylinder 40 acts to maintain a lip 55 of each finger 45 in position to engage a work sheet W as illustrated in Fig. l and press such work sheet against an anvil surface 56 of the cylinder 40.

At the proper time in the cycle of revolution of the cylinder 40 the cam 50 opens the gripper fingers S5 for the reception of a work sheet. After such work sheet passes the bite of the cylinders 36 and 4f) the cam 50 acts to release the gripper fingers 45 and the cylinders themselves coact to progress the work sheet. Any suitable mechanism, generally indicated at 58, may be used to insure stripping of the work sheet from the impression cylinder. A more complete illustration of the paper receiving and ejecting mechanisms may be had by reference to Patent No. 1,968,849 heretofore mentioned.

The offset cylinder 3%) is mounted for rotation about an axis which is movable in a circular path, the center or axis of which is fixed relative to the axes of rotation of the master cylinder 26 and the impression cylinder 40.

This may be accomplished by rotatably mounting the offset cylinder 30 on a shaft 32 which is illustrated in Figs. 2 and 4 as having eccentric end portions 34 journaled for rotation in respective frame members 10. When the offset cylinder 30 is mounted as above described and the shaft 32 turned, the axis of the offset cylinder 30 moves in a circular path about the axis of the eccentric ends 34 of the shaft. The radius of this path is equal to the amount of eccentricity between the center portion of the shaft on which the offset cylinder 39 is journaled and the end portions 34 thereof. This path has been designated by the character 35 in the diagram of Fig. 6. In this figure the axes of rotation of the master and impression cylinders 26* and 40 have been designated 21 and 41 respectively. While the axis of the eccentric end portions 33- of the shaft 32, which is the axis of the circular path, has been designated by the character 36. These three axes of centers are fixed relative to each other.

No. 1,968,849 heretofore men'- The axis of rotation 31 of the offset cylinder 36 is moved in the circular path 35 by an arm 60 secured to the shaft 32 and which, during normal printing operations, is retained in the position shown in Fig. l by a spring 61 interposed between a pin 62 affixed to a frame member 16 and the lower end of a link 63 pivotally connected intermediate its ends, as at 64, with the arm 6%. A latch member 65 pivotally mounted on a rod 66 extending between and journaled in the side frame member It engages a shoulder 68 formed on the arm 60 normally restrains rotation of the shaft 32 under the impulse of the spring 61.

As long as work sheets are fed to the impression cylinder 40 the position of the parts remains substantially unchanged from that shown in Fig. 1. However, should a work sheet fail to be fed to the impression cylinder 40 at the proper time, the latch 65 will move to release the arm 60 permitting the spring 61 to swing the arm and turn the eccentric shaft 32 to separate the offset cylinder 30 from both the master cylinder 26 and the impression cylinder 40.

The presence or absence of a work sheet is detected by a series of axially spaced feeler fingers 7t) shown as being secured to the rod 66. These fingers are normally positioned as shown in Fig. 3, spaced above a feed table 71 carried by the frame members 10, by a cam 72 secured to the shaft 32 and coacting with a roller 73 carried by a lever 74 which is secured to the rod 66. The unit including the fingers 7d, the arm 74, the roller 73, is so constructed and counter-weighted that its weight normally retains the parts in the position shown in Fig. 3 with the roller 73 in contact with the periphery of the cam 72, and the ends 6? of the fingers raised above the path of the work sheets fed across the table 71. At the proper time during the cycle of revolution of the cylinders 4t) and 36, which are drivingly geared together by suitable gearing, a notch or recess 75 formed in the cam 72 arrives at the position shown in Fig. l, whereupon the fingers 79 rock counter-clockwise due to the counterweighting of the parts as heretofore mentioned. Should a work sheet be present between the ends 69 of the fingers and the table 71 this movement is arrested by such work sheet and a spring 80 encircling the rod 66 with its ends coacting with the latch member 65 and the lever 94 respectively, acts to retain the latch in engagement with the arm 6% as shown in Fig. 1. However, should no sheet be present at this time the fingers 76, due to the counterweight action heretofore mentioned, rock counterclockwise through an opening 82 formed in the table 71 whereupon a pin carried by the lever 74 engages the latch 65 and moves the latch out of the path of the surface 68 of the arm 60, the pressure between the arm and latch having been relieved as will be hereinafter more fully described. The release of the arm 60 by the latch 65, as above described, permits the spring 61 to turn the eccentric shaft 32 in a clockwise direction.

The tension between the latch 65 and the arm 60 is relieved at the proper time by a cam 85 which is secured to the offset cylinder 30. This cam is 30 arranged that when the recess 75 of the cam 72 is opposite the cam roller 73, a high point 86 of the cam 85 engages a roller 87 carried intermediate the ends of the lever 88. One end of the lever 88 is pivotally mounted on a cross frame rod 90 and its other end is pivotally connected as at 91 to the upper end of the link 63 which, as heretofore described, is connected with the arm 65 and with the spring 61. When high point 86 of the cam 85 engages the roller 87, the link 63 rocks the eccentric shaft 32 in counterclockwise direction a distance sutlicient only to relieve the pressure between the latch 65 and the arm 6!) so that substantially no force is required to rock the arm 65 in its counterclockwise or work sheet detecting clirection.

The cam 85 also acts to reset the eccentric shaft and restorev the cylinders to their normal printing positions 5. fizhould a work sheet be present in the detecting position. ig. 3 illustrates the position of the various parts of the mechanism after the offset cylinder has been separated from the master and impression cylinders 20 and. 40. From inspection of this figure it will be seen that the roller 87 is in engagement with a low portion or surface 95 of the cam 85 thereby limiting the clockwise movement of the eccentric shaft. As the cam 85 rotates in a counterclockwise direction, due to the rotation of the cylinders, the high point 86 of the cam will again engage the roller 87 and rock the lever 88 counterclockwise about its pivot 90, thus raising the link 63 and returning the lever 60 to the position shown in Fig. 1 whereupon, should paper be present beneath the detector fingers 70, the latch 65 will rock into engagement with the arm 60 and again coact with the shoulder 68 to retain the mechanism in its normal printing position.

When it is desired to separate the offset cylinder 30 from the impression cylinder 40 and retain it in contact with the master cylinder 20 for purposes of inking the image on the printing plate 23 and building up an inked image on the offset blanket 37, which encircles the offset cylinder, the operator interrupts the work sheet feed and moves a pawl 92 into engagement with the link 63. The pawl is secured to a pin 93 carried by the adjacent frame member and has secured to its outer end an operating handle 94, the position of which'may be manually controlled. Under normal printing conditions the pawl 92 is in the position shown in Fig. 3 and is maintained in this position by the counterweight action of the operating handle 94.

When the pawl 92 is moved by the operator to the position shown in Figs. 1 and 2 it so engages the link 63 that the upper end of the pawl liesbelow a shoulder 67 formed on the link. Accordingly, if a work sheet is not in position paper detector fingers 70 will cause the latch 65 to release the arm 6%, whereupon the spring 61 draws the link 63 downward. This downward movement of the link is arrested by the engagement of the shoulder 67 of the link with the pawl 92. The tension between the parts retainsthem in engagement. The position of the cylinders at this time are best shown in Fig. 2 where it will be noted that the offset cylinder 3ft is in contact with the master cylinder 21 but is spaced from the impression cylinder 40.

The relation of the various cylinders, the circular path in which the axis of rotation of the offset cylinder and their axes, one to the other, is best illustrated in Fig. 6. The fixed axis of the master cylinder 2% is indicated at 21; the movable axis of rotation of the offset cylinder 36 at 31; the fixed axis of the circular path 35 at 36; and the fixed axis of the impression cylinder at 41.

The axis 41 of the impression cylinder 40 is positioned sothat a line 10d extending between such axis and the I path axis 36 forms an angle 161 of less than one hundred and eighty degrees with a line 102 measured in a counterclockwise direction from the latter, While maintaining the distance between the axes 21 and 41 greater than the sum of the radii of their respective cylinders. When the cylinders are in their normal printing positions, a line 103 extending between the axis 31 of impression cylinder and the path axis 36 forms an angle 1% with the line 12 which angle is smaller than the angle 101 as measured in a counterclockwise direction from the line 102, and the sum of the radii of the circular path 35 and offset cylinder 30 is less than the sum of the radii of the master and offset

cylinders

20 and 30.

Movement of the eccentric shaft 32 from the position shown in Fig. l to the position shown in Fig. 3 in re sponse to the absence of a work sheet beneath a feeler finger 70, the pawl 92 being positioned to interrupt movement of the link 63, causes the axis of the offset cylinder 30 to move clockwise (Fig. 6) to the position indicated at 31A, and the cylinder itself to the position indicated at 30A. The line 103A extending between the repositioned the line 162.

axis 31A and the axis 36 new forms the angle 104A with This angle is the same as the angle 104 but is measured in a clockwise direction from the line 102. Hence the cylinder SfiA coacts the cylinder 20 with the same printing pressure as existed when it was in the position 30. However, the cylinder 30 has been sepa rated from the impression cylinder 41).

As heretofore explained absence of a work sheet be neath the fingers '70 when the pawl 92 in the position shown in Fig. 3 causes the axis 31 of the offset cylinder to move through a greater angular distance than when the pawl 92 is in its arresting position. Such position of the oifset cylinder is indicated in Fig. 6 at 3%B and its axis at 313.

It is recognized that movement of the offset cylinder from the position 36' to either of its positions 30A or 3GB causes it to approach the master cylinder 26. It has been found that when offset and master cylinders each have a diameter of substantially seven inches; the angle 1131 established as one hundred and five degrees; the

angles

104 and 104A as five degrees; and the radius of the eccentric path at about seven hundredths of an inch; movement of the axis of the offset cylinder 30 from the position shown in Fig. 6 at 31 until it intersects the line 1&2 causes the cylinders 2t: and 30 to approach each other a negligible amount and, for practical purposes, may be disregarded as it merely increases the pressure between the master andoffset cylinders slightly above that desired during the normal printing operation and is readily accommodated by compression of the rubber-like offset blanket 37. However, it is contemplated that in other instances the mechanisms would be so timed that the gaps in the peripheries of the cylinders, in which gaps the printing plate and offset blankets clamp or retaining devices are positioned, would be opposite each other during the movement of the cylinders from one position to the other and would thus enable the required movement of the offset cylinder while it is out of peripherial contact with the master cylinder. Such gaps are indicated in Fig. 6 by the dotted lines 110.

In the example above set out the movement of the offsetcylinder to the position 30A causes a separation between the offset and

impression cylinders

30 and 40 which is sutficient to prevent transfer of ink from the surface of the offset cylinder 30 to the surface of the impression cylinder. Further, in the example given the three cylinders may be geared together by gears carried by the respective cylinders, the movement of the otfset cylinder being insufficient to disengage such gears, and the movement of the offset cylinder through a total angle of about forty degrees to the position 3013 causes a separation between the master cylinder 24) and the offset cylinder 31 sufficient to relieve the printing pressure between the cylinders and prevent transfer of ink from the master cylinder to the ofiset cylinder. Such movement also increases the separation between the ofiset cylinder 30 and the impression cylinder 40.

I claim:

1. In a rotary offset printing machine having a master cylinder, an impression cylinder, and an offset cylinder normally positioned to coact with the master cylinder to receive an inked image therefrom and to coact with the impression cylinder to transfer such image to a work sheet passed therebetween, means to support said offset cylinder for movement from said normal position to a second position to coact with the master cylinder to receive an inked image therefrom but separated from the impression cylinder, and for movement to a third position where it is separated from both master and impression cylinders, means acting automatically consequent upon the absence of a Work sheet to move said offset cylinder to one of said last-named positions, and manually operable means to selectively determine such second and third positions.

2. In a rotary offset printing machine according to claim 1, means to support said offset cylinder for bodily movement of its axis of rotation in a circular path the axis of which is fixed relative to the axes of the master and impression cylinders, the axis of said offset cylinder being movable in said path from its normal position to said other positions.

3. In a rotary offset printing machine having a master cylinder, an impression cylinder and an offset cylinder normally positioned to coact with the master cylinder to receive an inked image therefrom and to coact with the impression cylinder to transfer such image to a work sheet passed therebetween, support means to support said offset cylinder for movement from said position to a second position where it coacts with the master cylinder and is separated from the impression cylinder, and by a continuation of said movement to a third position where it is separated from the master and impression cylinders, means acting automatically consequent upon the absence of a work sheet to move said offset cylinder to said lastnamed position, and manually operable means to selectively interrupt said movement when said offset cylinder reaches said second named position.

4. In a rotary offset printing machine according to claim 3, wherein said support means includes means movable in a circular path the axis of which is fixed relative to the axes of the master and impression cylinders, the axis of said offset cylinder being movable in said path from its normal position to said other positions.

5. In a rotary offset printing machine having a master cylinder, an impression cylinder, an offset cylinder normally positioned to coact with the master cylinder to receive an inked image therefrom and to coact with the impression cylinder to transfer such image to'a work sheet passed therebetween and having a gear drivingly connected thereto, a gear drivingly connected with each of said other cylinders and in meshing engagement with the first named gear, means to support said offset cylinder for movement from said position to a second position where it coacts with the master cylinder and is separated from the impression cylinder and by a continuation of said movement to a third position where it is separated from the master cylinder and from the impression cylinder while maintaining a drivingconnectio-n between'said gears, means acting automatically consequent uporrthe absence of a work sheet to move said o'nset cylinder.to said last-named position, means to selectively interrupt.

said movement when said offset cylinder reaches said second position, and means to restore said cylinder to its,

normal position.

6. In a rotary offset printing machine according to claim 5, wherein said supporting means includes a shaft journaled for movement about an axis parallel with and fixed relative to the axes of the master and impression cylinders, said shaft having an eccentric portion rotat ably supporting said offset cylinder and an operating con: nection between said automatically operating means and said shaft to swing said shaft about its axis of rotation consequent upon the absence of a Work sheet.

7. In a rotary offset printing .machine accordingito claim 5, a latch normally acting to retain said offset,

cylinder in its normal position, resilient means tending to move said offset cylinder to its other positions, a cam acting to relieve the pressure on said latch at a predetermined time in the cycle of revolution of said cylinders, and means responsive to theabscnce of a work sheet to release said latch.

8. in a rotary offset "printing machine according to claim 7, a latch normally acting on said shaft to retain said offset cylinder in its normal position, resilient means coacting with said shaft and tending to move said offset cylinder to its otherpositions, a cam carried by'said cylinder, means interconnecting said cam with said latch to relieve pressure on said latch at a predetermined time in the cycle of revolution of said cylinders, means responsive to the absence of a work sheet to release said latch, means including said -cam "to restore said offset- 5% cylinder to'its-normal position, and means to restore said latch to its latching position consequent upon the restoration of said last-named cylinder to its normal position.

9. In a rotary offset printing machine having a master cylinder, an impression cylinder, an offset cylinder normally positioned to coact With the master cylinder to receive an inked image therefrom and to coact with the impression cylinders to transfer such image to a Work sheet passed-therebetween, means to support said offset cylinder being mounted with its axis movable bodily in a circular path the axis of which is fixed relative to the axesof the master and impression cylinders, said axes normally being so positioned that a line extending between the fixed axis of the master cylinder and axis of the circular path forms an angle of less thanone hundred and eighty degrees with a line extending between the axis of said path and the axis of the impression cylinder and a smaller angle measured in the same direction with a line extending between the axes of said path and offset cylinder, means acting automatically consequent upon the absence of a worksheet to move the axis of said offset-cylinder in said circular path away from said impression cylinder until a line extending between the axes of the offset cylinder and said path forms a greater angle claim 9, a latch normally acting to retain the axis of said offset cylinder in its normal position, resilient means tending to move the axis of said offset cylinder in said circular path, means acting automatically responsive to the absence .of a work sheet to release said latch, and means including a cam secured to said offset cylinder to automatically restore said offset cylinder to its normal position.

11. In a rotary offset printing machine having a master cylinder, an impression cylinder, an offset cylinder normally positioned to coact with the master cylinder to receive an inked image therefrom and to coact with the impression cylinders to transfer such image to a work sheet passed therebetween, means supporting said offset cylinder with its axis bodily movable in a circular path the axis of which is fixed relative to the axes of the master and impression cylinders, said axes being so positioned in their normal printing positions that a line extending between the fixed axis of the master cylinder and axis of the circular path forms an angle of less than one hundred and eighty degrees with a line extending between the axes of said path and impression cylinder and a smaller angle measured in the same direction with a line extending between the axes of said path and offset cylinder, the distance between the axes of the master and impression cylinders being greater than the sum of their radii, means responsive to the absence of a work sheet to move said offset cylinder axis in said path and away from said impression cylinder until a line extending between the axes of the offset cylinder and said path forms an angle with said first named line greater than said second named angle and measured in the opposite direction, and manually operable means to interrupt said movement when said second and last-named angles are equal, and wherein the distance between the axis of said circular path and the axis ofthe master cylinder is greater than the sum of the radii of the offset cylinder and the circular path.

References Cited in the file of this patent UNITED STATES PATENTS 1,718,900 Fischer June 25, 1929 2,387,750 Davidson Oct. 30, 1945 2,547,470 Janke Apr. 3, 1951