EP0028677A1

EP0028677A1 - Method and apparatus for both multicolor and blanket-to-blanket printing

Info

Publication number: EP0028677A1
Application number: EP80104570A
Authority: EP
Inventors: Lee Bullen
Original assignee: Publishers Equipment Corp
Current assignee: Publishers Equipment Corp
Priority date: 1979-11-07
Filing date: 1980-08-02
Publication date: 1981-05-20
Also published as: JPS5667259A

Abstract

A method and apparatus for changing an offset printing press between blanket-to-blanket, multicolor, and throw-off modes of operation so that no plate, blanket, or impression cylinder needs more than two positions is disclosed. A method of sequencing the movement of cylinders is also disclosed.

In a web fed offset printing press unit (10) the combination includes a frame (12), first and second plate cylinders (14 and 14a), ink transfer rollers and drums (16), first and second blanket cylinders (22 and 22a), an impression cylinder (24), and means (66) for bodily swinging the first blanket cylinder, the first plate cylinder, and the impression cylinder. Means is also included for bodily swinging the second blanket cylinder for throw-off.

In a combination including at least a half deck (26), a third blanket cylinder (28) and a third plate cylinder (30) are also included as well as means (66) for bodily swinging the third blanket cylinder from one position in contact with the impression cylinder in either impression cylinder position and a throw-off position.

Description

Technical Field

The present invention relates generally to printing presses, and in one of its aspects, to a method and apparatus for both multicolor and blanket-to-blanket printing.
The news publishing industry has an enormous investment in its printing equipment. In order to make maximum use of that equipment, it is highly desirable for a newspaper to be able to use a single press for both its multicolor printing and its black printing. Multicolor printing is normally three-color printing or three color plus black. When a printing press operates as a multicolor printer, it normally has three or four sets of rollers which act independently to apply the colors one at a time to a single side of the web. When a press is operating in the black mode, on the other hand, it is normally expected to print on both sides of the web. In offset printing, this is frequently accomplished by running the web between two blanket cylinders in what is known as blanket-to-blanket printing. If there is an additional blanket cylinder and an impression cylinder associated with that press, then it can be used to apply an extra color on one side of the web. This is known as "spot color" or "single color perfected" printing. In the multicolor mode, the web is frequently wrapped around an impression cylinder which is in rolling contact with the three or four blanket cylinders.
In addition to the multicolor and blanket-to-blanket modes, presses also have a throw-off mode in which the cylinders are no longer in contact. The throw-off mode is used for putting new plates on the plate cylinders, but it is also useful for untangling a web which has wrapped itself around a cylinder due to a web break, We_D breaks and web wraps are chronic and expensive problems that plague the news publishing industry.

Background Art

One offset printing press capable of operating in either multicolor or perfecting modes is shown in U. S. Patent No. 3,329,086 of Donald A. Pullen. One press shown in that patent includes two laterally spaced plate cylinders in rolling contact with two blanket cylinders arranged in close proximity to each other and an impression cylinder arranged closely adjacent the two blanket cylinders. The blanket cylinders are journaled in three position eccentric sleeves mounted in the frame for rocking movement in opposite directions from a central throw-off position. Rocking the blanket cylinders one way puts the blanket cylinders in contact for blanket-to-blanket operation, and rocking them the other way puts them in contact with the impression cylinder and out of contact -with each other for multicolor printing. The blanket cylinders are rocked simultaneously, and the linkage by which the rocking is accomplished includes a jack screw which extends through one of the pivot pins in the linkage. Due to the complexity of the three positions and simultaneous movement of the blanket cylinders, it is necessary to manually adjust the jack screw one way for one end position and adjust it in the opposite direction for the other end position. In addition, the clearance between the two blanket cylinders in the multicolor mode and the clearance between the blanket cylinders and the impression cylinder in the perfecting mode are quite small, in the neighborhood of 40 thousandths of an inch in some cases. As a result of these small clearances, web jams can be very troublesome. The web is more likely to jam causing damage to plates and blankets, and clearing the jam is more difficult.

Disclosure of Invention

In accordance with the present invention, a web fed offset printing press unit for multicolor and blanket-to-blanket printing includes the combination of a frame, first and second plate cylinders laterally spaced in the frame for mounting printing plates thereon, means for applying films of ink to the plates, first and second blanket cylinders in rolling contact with the plates on the first and second plate cylinders respectively, and an impression cylinder arranged closely adjacent to the two blanket cylinders. The blanket cylinders are also arranged closely adjacent one another. The combination also includes a means for bodily swinging the first blanket cylinder through a short radius arc between a blanket-to-blanket position in which the blanket cylinders make contact with each other and a multicolor position in which the blanket cylinders do not make contact with each other. A means for bodily swinging the first plate cylinder through a short radius arc between a blanket-to-blanket position in which the first plate cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the blanket-to-blanket position and a multicolor position in which the first plate cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the multicolor position is also included. The combination also includes means for bodily moving the impression cylinder, usually a means for bodily swinging the impression cylinder through a short radius arc, between a throw-off position in which the impression cylinder is displaced from both blanket cylinders and a multicolor position in which the impression cylinder makes contact with both blanket cylinders when the first blanket cylinder is in the multicolor position. A means is provided for driving the cylinders with provision for reversing the direction of rotation of one of the blanket cylinders and its cooperating plate cylinder in the respective modes of operation.
A preferred form of the present invention includes means for bodily swinging the second blanket cylinder through a short radius arc between an operating position in which the second-blanket cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the blanket-to-blanket position and with the impression cylinder when the impression cylinder is in the multicolor position, and a throw-off position in which the second blanket cylinder is isolated from the other cylinders.
One arrangement of the present invention also includes a means for sequencing the bodily swinging of cylinders in changing from a multicolor configuration to a throw-off configuration and in changing from a throw-off configuration to a multicolor configuration. In going from a multicolor configuration to a throw-off configuration, the impression cylinder is swung into the throw-off position prior to swinging the second blanket cylinder into its throw-off position. In changing from the throw-off configuration to the multicolor configuration, the second blanket cylinder is swung into the multicolor position prior to swinging the impression cylinder into its multicolor position.
In an arrangement of the present invention including at least a half deck, which is to say a half deck or a full deck, a third blanket cylinder is rotatably mounted in the half deck closely adjacent to the impression cylinder and a third plate cylinder is rotatably mounted in the half deck closely adjacent to the third blanket cylinder for rolling contact with the third blanket cylinder. Such a combination includes a means for bodily swinging the third blanket cylinder through a short radius arc between a position which is in contact with the third plate cylinder and the impression cylinder in either impression cylinder position and a throw-off position in which the third blanket cylinder is isolated from the other cylinders. In such ar, arrangement the impression cylinder throw-off position is also a perfected printing position. In such an arrangement, the means for sequencing the bodily swinging of cylinders swings the third blanket cylinder into the throw-off position prior to swinging the blanket cylinder into its throw-off position and swings the impression cylinder into its multicolor position prior to swinging the third blanket cylinder into its multicolor position.
A method according to the present invention for changing an offset printing press having a frame, first and second plate cylinders laterally spaced in the frame, first and second blanket cylinders arranged closely adjacent one another and their respective plate cylinders, and an impression cylinder closely adjacent the blanket cylinders, from a multicolor configuration into a throw-off configuration, includes the combination of first bodily swinging the impression cylinder through a short radius arc from a multicolor position in which it makes contact with both blanket cylinders to a throw-off position in which it is isolated from both blanket cylinders, bodily swinging the second blanket cylinder through a short radius arc from a position in contact with the second plate cylinder for both multicolor and blanket-to-blanket configurations to a throw-off position in which the second blanket cylinder is isolated from the other cylinders, and bodily swinging the first plate cylinder through a short radius arc from a multicolor position in which the first plate cylinder makes contact with the first blanket cylinder to a throw-off position in which the first plate cylinder is isolated from the other cylinders when the first blanket cylinder is in its multicolor position. Such a method for use with at least a half deck includes, prior to bodily swinging the impression cylinder, bodily swinging the third blanket cylinder through a short radius arc from a multicolor position in contact with the impression cylinder and the third plate cylinder to a throw-off position in which the third blanket cylinder is isolated from the other cylinders.
A method according to the present invention for configuring such a press unit into a multicolor configuration includes the combination of bodily swinging the first plate cylinder through a short radius arc into contact with the first blanket cylinder, bodily swinging the second blanket cylinder through a short radius arc into contact with the second blanket cylinder, and after bodily swinging the second blanket cylinder, bodily swinging the impression cylinder through a short radius arc into contact with both the first and second blanket cylinders. Such a method for use with at least a half deck also includes, after bodily swinging the impression cylinder, bodily swinging the third blanket cylinder through a short radius arc into contact with the impression cylinder.
It is one object of the present invention to allow change of a printing press from spot color to multicolor or from multicolor to spot color by merely pushing a button without making significant adjustments, thereby reducing the possibility of human error in switching from one printing mode to the other.
It is another object of the present invention to allow cylinders to be moved into place separately in sequence in order to reduce the likelihood of web breaks.
It is another _Qbject of the present invention to provide a web fed offset printing press which can be changed between blanket-to-blanket mode and multicolor mode while leaving additional clearance between the cylinders in case of a web break.
These and other objects, advantages and features of this invention will be apparent from the following description taken with reference to the accompanying drawings, wherein is shown the preferred embodiments of the invention.

Brief uescription of Drawinar

FIGURE 1 is a diagramatic cross-sectional view taken from one end of a web fed offset printing press unit according to the present invention;
FIGURE 2 is an enlarged diagramatic sectional view similar to that of FIGURE 1 of the offset cylinders of tne offset press unit of FIGURE 1;
FIGURE 2a is a view similar to that of FIGURE 2 showing a single color perfected configuration and a throw-off configuration;
FIGURE 2b is a view similar to that of FIGURE 2 showing a multicolor configuration and a throw-off configuration;
FIGURE 3 is an elevational view of one means for bodily swinging a cylinder through a short radius arc;
FIGURE 4 is an alternative arrangement of a means for swinging a cylinder through a short radius arc; and
FIGURE 5 is a diagramatic representation of one means for sequencing the bodily swinging of cylinders.

Best Mode for Carrying Out the Invention

Referring now to the drawings, and in particular FIGURE 1, a web fed offset printing press unit according to the present invention for multicolor and blanket-to-blanket printing is referred to generally by reference numeral 10. Configured as shown, press 10 prints on both sides of web 11 and adds spot color to one side. Offset press unit 10 includes a main frame 12, first and second plate cylinders 14 and 14a laterally spaced in frame 12 for mounting printing plates thereon, means including ink transfer rollers and cylinders or drums 16 and 16a and form rollers 18, 18a, 20 and 20a for applying films of ink to the plates. Offset press unit 10 also includes first and second blanket cylinders 22 and 22a in rolling contact with the plates on the first and second plate cylinders 14 and 14a respectively, the blanket cylinders being arranged closely adjacent one another. An impression cylinder 24 is arranged closely adjacent to the two Blanket cylinders.
In an arrangement of the present invention which includes at least a half deck 26, but which could include a full deck, a third blanket cylinder 28 is rotatably mounted in half deck 26 closely adjacent to impression cylinder 24. A third plate cylinder 30 is rotatably mounted in half deck 26 closely adjacent to third blanket cylinder 28 for rolling contact with the third blanket cylinder. Throughout this description, the term "contact" is used in describing the relationship between cylinders in the normal usage of the term in the industry to include the situation where the web is between the two cylinders, preventing contact in a literal sense or in the situation where the plates of a plate cylinder are between the actual plate cylinder and its adjacent blanket cylinder.
Referring now to FIGURE 2 and FIGURE 2b, a method for changing an offset printing press 10 from a multicolor configuration into a throw-off configuration includes the combination of first bodily swinging impression cylinder 24 through a short radius arc represented by line 32 from a multicolor position 34 in which impression cylinder 24 makes contact with both blanket cylinders 22 and 22a to a throw-off position 36 in which impression cylinder 24 is isolated from both blanket cylinders, bodily swinging second blanket cylinder 22a through a short radius arc represented by line 38 from a position 40 in contact with second plate cylinder 14a for both multicolor and blanket-to-blanket configurations to a throw-off position 42 in which second blanket cylinder 22a is isolated from the other cylinders, and bodily swinging first plate cylinder 14 through a short radius arc represented by line 44 from a multicolor position 46 in which first plate cylinder 14 makes contact with first blanket cylinder 22 to a throw-off position 48 in which the first plate cylinder is isolated from the other cylinders when first blanket cylinder 22 is in its multicolor position 50. In general, the order of swinging second blanket cylinder 22a and first plate cylinder 14 is immaterial. Such a method for an arrangement having a half deck includes, prior to bodily swinging impression cylinder 24, bodily swinging third blanket cylinder 28 through a short radius arc represented by line 52 from a multicolor position 54 in contact with impression cylinder 24 and' third plate cylinder 30 to a throw-off position 56 in which the third blanket cylinder is isolated from the other cylinders. Referring also to FIGURE 5, one means for sequencing the bodily swinging of cylinders to accomplish this method is referred to generally by reference numeral 108. Means 108 includes four means 110, 112, 114 and 116 for bodily swinging cylinders 28, 24, 22a and 14 respectively. When button 118 is closed, means 110 is activated to swing third blanket cylinder. After a time delay caused by time delay means 120, means 112 is activated to swing impression cylinder 24, followed by another time delay 122 and activation of means 114, and finally a time delay 124 and activation of means 116. In one arrangement, the time delays are sufficiently long for the previous means for bodily swinging a cylinder to finish. Power to means 108 is supplied by a power supply 126, and a resistor 128 provides bias for means 116. Alternative means for sequencing could be arranged by a valving sequence if hydraulic or pneumatic valves are used for the means for bodily.swinging cylinders.
A method for configuring offset printing press 10 into a multicolor configuration includes the combination of bodily swinging first plate cylinder 14 through short radius arc 44 into contact with first blanket cylinder 22, bodily swinging second blanket cylinder 22a through short radius arc 38 into contact with second plate cylinder 14a, and after bodily swinging second blanket cylinder 22a, bodily swinging impression cylinder 24 through short radius arc 32 into contact with both first and second blanket cylinders 22 and 22a. In such a method for an arrangement having at least a half deck, the combination includes, after bodily swinging impression cylinder 24, bodily swinging third blanket cylinder 28 through short radius arc 52 into contact with the impression cylinder.
Referring also to Figure 2a, a method of changing press 10 from a throw-off configuration to a blanket-to-blanket configuration for printing on both sides of a web fed between blanket cylinders 22 and 22a includes the steps of bodily swinging blanket cylinder 22 through a short radius arc represented by line 58 from multicolor position 50 which is also the throw-off position to blanket-to-blanket position 60, and bodily swinging second blanket cylinder 22a through short radius arc 38 from throw-off position 42 to operating position 40. In general the order of the steps is immaterial, but swinging blanket cylinders 22 and 22a one at a time into the blanket-to-blanket positions rather than simultaneously is less likely to cause a web break. Throw-off position 48 for first plate cylinder 14 is also the blanket-to-blanket position for that cylinder. In a preferred arrangement, second blanket cylinder 22a and second plate cylinder 14a form a mirror image of first blanket cylinder 22 and first plate cylinder 14 in the blanket- to-blanket mode of operation since web 11 is normally run straight up between the two blanket cylinders.
Short radius arc 58 is chosen so that the distance from multicolor and throw-off position of first blanket cylinder 22 is further from blanket-to-blanket and throw-off position 48 of first plate cylinder 14 than is blanket-to-blanket position 60. Similarly, short radius arc 38 is chosen so that throw-off position 42 is further from the center 62 of second plate cylinder 14a than is operating position 40. Short radius arc 32 of impression cylinder 24 is chosen so that throw-off position 36 is further from multicolor and throw-off position 50 of first blanket cylinder 22 than is multicolor position 34 while at the same time being further from throw-off position 42 of second blanket cylinder 22a than the combined radiuses of second blanket cylinder 22a and impression cylinder 24. The additional constraint on the postitions for impression cylinder 24 is that three-color position 34 and throw-off/perfecting position 36 are equal distances from operating position 54 of third blanket cylinder 28. The additional restraint on short radius arc 52 is that throw-off position 56 is further away from the center 64 of third plate cylinder 30 than is operating position 54.
Referring now to Figure 3, one means for bodily swinging first blanket cylinder 22 through short radius arc represented by line 5.8 between blanket-to-blanket position 60 and multicolor position 50 which is also the throw-off position is represented generally by reference numeral 66. Blanket cylinder 22 is journaled in eccentric sleeve 68 at one end and an identical sleeve at the opposite end. When first blanket cylinder 22 is in the blanket-to-blanket position 60, ear 70 which is affixed to eccentric sleeve 68 abutts stop 72, and pivot points 74 and 76 of dogleg link 78 align with the center 80 of rotating shaft 82 and hub 84 which is affixed to rotating shaft 82, to lock first blanket cylinder 22 in place.
When first blanket cylinder 22 is in multicolor and throw-off position 50, then ear 86 abutts stop 88 as shown in dashed lines. Pivot points 74 and 76 have moved to new positions, labeled "B" so that pivot point 76 is on the opposite side of center 80 of rotating shaft 82. Once again, pivot points 74 and 76 align with center 80 so that cylinder 22 is locked into place.
Referring to Figure 4, an alternative embodiment of a means for bodily swinging first blanket cylinder 22 is referred to generally by reference numeral 90. Once again ear 70 oi eccentric sleeve 68 abutts stop 72 when first blanket cylinder 22 is in the blanket-to-blanket mode which is represented generally by the letter "A", and ear 86 abutts stop 88 when first blanket cylinder 22 is in the multicolor and throw-off position, the multicolor and throw-off mode being represented generally by the letter "B". Cylinder 92 which can be a hydraulic or pneumatic cylinder is pivotally connected to the frame by pivot connection 94. Piston rod 96 is pivotally connected to one end of link 98 at pivot point 100. The opposite end of link 98 is pivotally connected to eccentric sleeve 68 at pivot point 102. In addition, link 104 pivotally connects pivot point 100 and a point 106 which is stationary with reference to frame 12 so that pivot point 100 is in line between pivot point 102 and point 106 when first blanket cylinder 22 is in blanket-to-blanket position 60, locking the blanket cylinder into position. Likewise, when first blanket cylinder 22 is in the multicolor and throw-off position 50, pivot points 100 and 102 align with piston rod 96, locking the first blanket cylinder 22 into place.
Since none of the cylinders require more than two positions in order to make the press function properly, means for bodily swinging the cylinders such as means 66 and means 90 can be used for all of the cylinders which need to be bodily moved. It can thus be seen that an offset printing press according to the present invention includes a.means such as means 66 for bodily swinging first blanket cylinder 22 through short radius arc 58 between blanket-to-blanket position 60 in which the blanket cylinders make contact with each other for applying an inked image on opposite sides of web 11 fed between them and a multicolor position 50 in which the blanket cylinders do not make contact with each other, means such as means 66 for bodily swinging first plate cylinder 14 through short radius arc 44 between blanket-to-blanket position 48 in which the first plate cylinder makes contact with first blanket cylinder 22 when first blanket cylinder 22 is in the blanket-to-blanket position and multicolor position 46 in which the first plate cylinder makes contact with first blanket cylinder 22 when the first blanket cylinder is in the multicolor position, and means such as means 66 for bodily swinging impression cylinder 24 through short radius arc 32 between throw-off position 36 in which the impression cylinder is isolated from both blanket cylinders and multicolor position 34 in which the impression cylinder makes contact with both blanket cylinders when first blanket cylinder 22 is in the multicolor position for applying inked images successively to one side of web llb fed about the impression cylinder. Such a combination can also include means such as means 66 for bodily swinging second blanket cylinder 22a through short radius arc 38 between operating position 40 in which the second blanket cylinder makes contact with the first blanket cylinder 22 when the first blanket cylinder is in the blanket-to-blanket position and with impression cylinder 24 when the impression cylinder is in the multicolor position, and throw-off position 42 in which the second blanket cylinder is isolated from the other cylinders. In a press including at least a half deck, the combination includes means such as means 66 for bodily swinging third blanket cylinder 28 through short radius arc 52 between a position 54 which is in contact with third plate cylinder 30 and impression cylinder 24 in either impression cylinder position so that the impression cylinder throw-off position is also a perfected printing position, and throw-off position 56 in which third blanket cylinder 28 is isolated from the other cylinders. It is not always necessary to swing impression cylinder 24 through a short radius arc. In some arrangements it can be bodily moved such as linearly by a slider.
Means for driving the cylinders with provision for reversing the direction of rotation of one of the blanket cylinders and its cooperating plate cylinder in the respective modes of operation are well known in the art. One suitable means is shown and described in U. S. Patent No. 3,329,086 of D. A. Pullen.
It can thus be seen that the present invention allows the switching from blanket-to-blanket or perfected printing to multicolor printing through a toggle arrangement which positively locks and locates the cylinders without resorting to a jackscrew arrangement, thus reducing the chance for human error. Furthermore, since the gaps between adjacent cylinders which are not in contact with each other can be increased from in the neighborhood of 40 thousandths of an inch to the neighborhood of 1/8 to 1/4 of an inch, use of the present invention is much less likely to cause damage to plates and blankets due to lockups caused by web jams. The larger gaps also reduce the down time due to web breaks and web jams.
From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.
It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.
As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Claims

1. In a web fed offset printing press unit for multicolor and blanket-to-blanket printing, the combination comprising:

a frame;

first and second plate cylinders laterally spaced in the frame for mounting printing plates thereon;

means for applying films of ink to the plates;

first and second blanket cylinders in rolling contact with the plates on the first and second plate cylinders- respectively, the blanket cylinders being arranged closely adjacent one another;

an impression cylinder arranged closely adjacent to the two blanket cylinders;

means for bodily swinging the first blanket cylinder through a short radius arc between a blanket-to-blanket position in which the blanket cylinders make contact with each other for applying an inked image on opposite sides of a web fed between them and a multicolor position in which the blanket cylinders do not make contact with each other;

means for bodily swinging the first plate cylinder through a short radius arc between a blanket-to-blanket position in which the first plate cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the blanket-to-blanket position and a multicolor position in which the first plate cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the multicolor position;

means for bodily swinging the impression cylinder through a short radius arc between a throw-off position in which the impression cylinder is isolated from both blanket cylinders and a multicolor position in which the impression cylinder makes contact with both blanket cylinders when the first blanket cylinder is in the multicolor position for applying inked images successively to one side of a web fed about the impression cylinder; and

means for driving the cylinders with provision for reversing the direction of rotation of one of the blanket cylinders and its cooperating plate cylinder in the respective modes of operation.

₂. A combination according to Claim 1 further comprising means for bodily swinging the second blanket cylinder through a short radius arc between an operating position in which the second blanket cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the blanket-to-blanket position and with the impression cylinder when the impression cylinder is in the multicolor position, and a throw-off position in which the second blanket cylinder is isolated from the other cylinders.

₃. A combination according to Claim 1 further comprising a means for sequencing the bodily swinging of cylinders wherein in changing from a multicolor configuration to a throw-off configuration, the impression cylinder is swung into the throw-off position prior to swinging the second blanket cylinder into its throw-off position, and in changing from a throw-off configuration to a multicolor configuration, the second blanket cylinder is swung into the multicolor position prior to swinging the impression cylinder into its multicolor position.

4. A combination according to Claim 1 further comprising:

at least a half deck;

a third blanket cylinder rotatably mounted in the half deck closely adjacent to the impression cylinder;

a third plate cylinder rotatably mounted in the half deck closely adjacent to the third blanket cylinder for rolling contact with the third blanket cylinder; and

means for bodily swinging the third blanket cylinder through a short radius arc between a position which is in contact with the third plate cylinder and the impression cylinder in either impression cylinder position whereby the impression cylinder throw-off position is also a perfected printing position, and a throw-off position in which the third blanket cylinder is isolated from the other cylinders.

5. A combination according to Claim 4 further comprising means for bodily swinging the second blanket cylinder through a short radius arc between an operating position in which the second blanket cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the blanket-to-blanket position and with the impression cylinder when the impression cylinder is in the multicolor position, and a throw-off position in which the second blanket cylinder is isolated from the other cylinders.

6. A combination according to Claim 5 further comprising a means for sequencing the bodily swinging of cylinders wherein in changing from a multicolor configuration to a throw-off configuration, the third blanket cylinder is swung into the throw-off position prior to swinging the blanket cylinder, and the blanket cylinder is swung into the throw-off position prior to swinging the second blanket cylinder into its throw-off position, and in changing from a throw-off configuration to a multicolor configuration, the second blanket cylinder is swung into its multicolor configuration prior to swinging the impression cylinder, and the impression cylinder is swung into its multicolor position prior to swinging the third blanket cylinder into its multicolor position.

7. In a web fed offset printing press unit for multicolor and blanket-to-blanket printing, the combination comprising:

a frame;

means for applying films of ink to the plates;

first and second blanket cylinders in rolling contact with the plates on the first and second plate cylinders respectively, the blanket cylinders being arranged closely adjacent one another;

an impression cylinder arranged closely adjacent to the two blanket cylinders;

means for bodily moving the impression cylinder between a throw-off position in which the impression cylinder is isolated from both blanket cylinders and a multicolor position in which the impression cylinder makes contact with both blanket cylinders when the first blanket cylinder is in the multicolor position for applying inked images successively to one side of a web fed about the impression cylinder; and

8. A combination according to Claim 7 further comprising means for bodily swinging the second blanket cylinder through a short radius arc between an operating position in which the second blanket cylinder makes contact with the first blanket cylinder when the first blanket cylinder is in the blanket-to-blanket position and with the impression cylinder when the impression cylinder is in the multicolor position, and a throw-off position in which the second blanket cylinder is isolated from the other cylinders.

9. A method for changing an offset printing press having a frame, first and second plate cylinders laterally spaced in the frame, first and second blanket cylinders arranged closely adjacent one another and their respective plate cylinders, and an impression cylinder closely adjacent the blanket cylinders, from a multicolor configuration into a throw-off configuration, comprising in combination:

first, bodily swinging the impression cylinder through a short radius arc from a multicolor position in which the impression cylinder makes contact with both blanket cylinders to a throw-off position in which the impression cylinder is isolated from both blanket cylinders;

bodily swinging the second blanket cylinder through a short radius arc from a position in contact with the second plate cylinder for both multicolor and blanket-to-blanket configurations to a throw-off position in which the second blanket cylinder is isolated from the other cylinders; and

bodily swinging the first plate cylinder through a short radius arc from a multicolor position in which the first plate cylinder makes contact with the first blanket cylinder to a throw-off position in which the first plate cylinder is isolated from the other cylinders when the first blanket cylinder is in its multicolor position.

10. A method according to Claim 9 for an offset printing press also having at least a half deck, a third blanket cylinder rotatably mounted in the half deck closely adjacent to the impression cylinder, and a third plate cylinder rotatably mounted in the half deck for rolling contact with the third blanket cylinder, further comprising, prior to bodily swinging the impression cylinder, bodily swinging the third blanket cylinder through a short radius arc from a multicolor position in contact with the impression cylinder and the third plate cylinder to a throw-off position in which the third blanket cylinder is isolated from the other cylinders.

11. A method for configuring an offset printing press having a frame, first and second plate cylinders laterally spaced in the frame, first and second blanket cylinders arranged closely adjacent one another and their respective plate cylinders, and an impression cylinder closely adjacent the blanket cylinders, into a multicolor configuration, comprising in combination:

bodily swinging the first plate cylinder through a short radius arc into contact with the first blanket cylinder;

bodily swinging the second blanket cylinder through a short radius arc into contact with the second plate cylinder; and

after bodily swinging the second blanket cylinder, bodily swinging the impression cylinder through a short radius arc into contact with both the first and second blanket cylinders.

12. A method according to Claim 11 for an offset press also having at least a half deck, a third blanket cylinder rotatably mounted in the half deck closely adjacent to the impression cylinder, and a third plate cylinder rotatably mounted in the half deck for rolling contact with the third blanket cylinder, further comprising, after bodily swinging the impression cylinder, bodily swinging the third blanket cylinder through a short radius arc into contact with the impression cylinder.