Variable format offset printing machine having a central impression cylinder

Abstract

Variable format offset printing machine having a central impression cylinder The printing machine comprises a central impression cylinder (1) on which a web printable substrate (B) is supported and a plurality of printing stations arranged around the central impression cylinder (1). Each printing station comprises a blanket cylinder (2) of variable diameter, a plate cylinder (3) of variable diameter, and an offset inking unit (4). Said blanket cylinder (2), plate cylinder (3) and offset inking unit (4) are individually movable between respective withdraw positions and respective multiple working positions for different diameters of the blanket and plate cylinders (2, 3). At least one of said printing stations has the axis of the blanket cylinder (2) and the axis of the plate cylinder (3) comprised in an inclined first plane (P1) which does not comprise the axis of the central impression cylinder (1) at any of said multiple working positions for different diameters of the blanket and plate cylinders (2, 3).

Claims

1. A variable format offset printing machine having a central impression cylinder, comprising said central impression cylinder on which a web printable substrate is supported and a plurality of printing stations arranged around the central impression cylinder, the central impression cylinder having a web inlet side and a web outlet side, each of said printing stations comprising a blanket cylinder of variable diameter, a plate cylinder of variable diameter, and an offset inking unit, said blanket cylinder, plate cylinder and offset inking unit being movable between respective withdrawn positions and respective multiple working positions for different diameters of the blanket and plate cylinders, wherein: the blanket cylinder and the plate cylinder are rotatingly supported on respective first and second supports connected by respective first and second horizontal linear guidance means to a main frame which rotatingly supports the central impression cylinder, said first and second supports being movable in linear horizontal directions between their withdrawn positions and their working positions; the offset inking units of all the printing stations which are located at one and the same web inlet or web outlet side of the central impression cylinder are mounted on at least one auxiliary frame in which the offset inking units are superposed on one another and staggered so as to follow the circumference of the central impression cylinder, said auxiliary frame being connected by horizontal linear guidance means to said main frame, the auxiliary frame being movable in a linear horizontal direction between its withdrawn position and its working position; and the main frame comprises an operator side main frame wall and a gear side main frame wall having respective middle regions on which the central impression cylinder is supported and operator side and gear side upper and lower beams horizontally extending from said middle regions of said operator side and gear side main frame walls and solidly connected thereto.

2. The printing machine according to claim 1, wherein each of the first supports comprises an operator side first support and a gear side first support respectively connected by linear guidance means to said middle regions of the operator side main frame wall and the gear side main frame wall, said operator side first support and said gear side first support carrying respective support means rotatingly supporting a blanket mandrel on which a blanket sleeve is mounted, said blanket mandrel and blanket sleeve forming together the blanket cylinder.

3. The printing machine according to claim 2, wherein said support means at the gear side first support are configured for supporting said mandrel in cantilever, and said support means at the operator side first support are configured to be opened and closed, the operator side first support being individually movable when the support means at the operator side first support are open for enabling the blanket sleeve to be axially installed to or removed from the blanket mandrel.

4. The printing machine according to claim 3, wherein a blanket cylinder-driving servomotor is carried on said gear side first support and connected for driving the rotating movement of the blanket cylinder.

5. The printing machine according to claim 1, wherein each of the second supports comprises an operator side second support and a gear side second support respectively connected by linear guidance means to said middle regions of the operator side main frame wall and the gear side main frame wall, said operator side second support and said gear side second support carrying respective support means rotatingly supporting a plate mandrel on which a plate sleeve is mounted, said plate mandrel and said plate sleeve forming together the corresponding plate cylinder.

6. The printing machine according to claim 5, wherein said support means at the gear side second support are configured for supporting said mandrel in cantilever, and the support means at the operator side second support are configures be opened and closed, the operator side second support being individually movable when the support means at the operator side second support are open for enabling the plate sleeve to be axially installed to or removed from the plate mandrel.

7. The printing machine according to claim 6, wherein a plate cylinder-driving servomotor is carried on said gear side second support and connected for driving the rotating movement of the plate cylinder.

8. The printing machine according to claim 1, wherein the auxiliary frame comprises a plurality of modular auxiliary frame parts staked on one another and connected to each other by releasable fastening means, each modular auxiliary frame part carrying one of the offset inking units or being a dummy modular auxiliary frame part.

9. The printing machine according to claim 8, wherein a modular auxiliary frame part carrying the uppermost offset inking unit is attached to operator side and gear side upper auxiliary frame-carriers which are movably connected by respective operator side and gear side upper horizontal linear guidance means to said operator side and gear side upper beams of the main frame and a modular auxiliary frame part carrying the lowermost offset inking unit is attached to operator side and gear side lower auxiliary frame-carriers which are movably connected by respective operator side and gear side lower horizontal linear guidance means to said operator side and gear side lower beams of the main frame.

10. The printing machine according to claim 8, wherein the modular auxiliary frame parts identical to one another and are staggered so as to follow the circumference of the central impression cylinder.

11. The printing machine according to claim 8, characterized in that, when the corresponding releasable fastening means are released, at least one the modular auxiliary frame part carrying the uppermost offset inking unit is shiftable away from the central impression cylinder while the rest of the staked modular auxiliary frame parts forming the auxiliary frame remain in their working positions to provide room for an alternative inking unit to be mounted.

12. The printing machine according to claim 1, wherein a main motor is supported on the gear side main frame wall, said main motor being connected for rotating the central impression cylinder, and a brake is supported at the operator side main frame wall, said brake being connected for braking the central impression cylinder.

13. The printing machine according to claim 1, wherein all the first supports which are located above and below a central horizontal plane comprising an axis of the central impression cylinder are identical design and symmetrically positioned both with respect to said central horizontal plane and to a central vertical plane comprising said axis of the central impression cylinder, and all the second supports which are located above and below the central horizontal plane are identical design and symmetrically positioned both with respect to the central horizontal plane and to said central vertical plane.

14. The printing machine according to claim 1, wherein the main frame has opposite operator and gear sides, and each first support comprises an operator side first support and a gear side first support independently movable from each other, and each second support comprises an operator side second support and a gear side second support independently movable from each other.

15. The printing machine according to claim 1, wherein a space accessible for an operator is provided between the auxiliary frame and all the first and second supports located at the same web inlet or web outlet side of the main frame when the auxiliary frame is in its withdrawn position.

16. The printing machine according to claim 1, wherein the uppermost and lowermost offset inking units of the superposed and staggered offset inking units which are located at one and the same web inlet or web outlet side of the central impression cylinder are attached to upper and lower auxiliary frame-carriers, and said upper and lower auxiliary frame-carriers are movably connected to upper and lower beams extending from a middle region of the main frame.

17. The printing machine according to claim 16, wherein a position of at least said uppermost offset inking unit is shiftable with respect to the rest of the superposed and staggered offset inking units forming the auxiliary frame.

18. The printing machine according to claim 16, wherein at least one of the superposed and staggered offset inking units is replaced with a dummy modular auxiliary unit providing a limited number of printing stations instead of the maximum possible number of printing stations and/or allowing space for additional drying or curing equipment.

19. The printing machine according to claim 8, wherein any of the stacked modular auxiliary frame parts forming the auxiliary frame are movable individually between the withdrawn and working positions.

20. The printing machine according to claim 1, wherein at least one of the printing stations comprises an alternative inking unit.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other features and advantages will become apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

(2) FIG. 1 is a diagrammatic operator side view of a variable format offset printing machine having a central impression cylinder according to an exemplary embodiment of the present invention with the offset printing stations in a working position;

(3) FIG. 2 is a diagrammatic operator side view of the offset printing machine of FIG. 1 with the printing stations in a withdrawn position;

(4) FIG. 3 is a diagrammatic partial operator side view showing a first and a second offset printing stations with respect to the movement direction of a web printable substrate supported on the central impression cylinder, with the first and a second offset printing stations positioned in respective first working positions suitable for pairs of blanket and plate cylinders of minimum format;

(5) FIG. 4 is a diagrammatic partial operator side view showing the first and second offset printing stations positioned in a second working position suitable for pairs of blanket and plate cylinders of maximum format;

(6) FIG. 5 is a diagrammatic operator side view of the printing machine with all the printing stations in the working position except the first one, the offset inking unit of which is in the withdrawn position;

(7) FIG. 6 is a partial cross-sectional view taken along the plane VI-VI of FIG. 2 showing the construction of the main frame supporting the central impression cylinder and one of the first supports carrying a blanket cylinder;

(8) FIG. 7 is a is a partial cross-sectional view taken along the plane VII-VII of FIG. 2 showing the construction of the main frame supporting the central impression cylinder and one of the second supports carrying a plate cylinder;

(9) FIG. 8 is a diagrammatic partial operator side view showing horizontal linear guidance means for the first and second supports;

(10) FIG. 9 is a partial plant view showing the construction of the main frame supporting the central impression cylinder and an auxiliary frame carrying a plurality of offset inking units supported on beams of the main frame;

(11) FIG. 10 is a cross-sectional view taken along the plane X-X of FIG. 5, showing the construction of the main frame and the auxiliary frame; and

(12) FIG. 11 is a diagrammatic operator side view of the variable format offset printing machine of FIG. 1 including a dummy modular auxiliary frame part.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(13) Referring first to FIGS. 1 and 2, there is shown an offset printing machine according to an exemplary embodiment of the present invention. The offset printing machine comprises a main frame 8 supporting a rotatable central impression cylinder 1 on which a web printable substrate B is supported and a plurality of printing stations arranged around said central impression cylinder 1. In operation, the central impression cylinder 1 rotates in the direction indicated by an arrow (counter clockwise in the Figures) and the web printable substrate B moves in the direction indicated with arrows as the central impression cylinder 1 rotates and comes in contact with the central impression cylinder 1 at a web inlet side thereof (left side in the Figures) and leaves the central impression cylinder 1 at an opposite web outlet side thereof (right side in the Figures). More specifically, in the illustrated exemplary embodiment there are four of said printing stations arranged at said web inlet side and other four printing stations arranged at said web outlet side.

(14) Each printing station comprises a blanket cylinder 2, a plate cylinder 3 and an offset inking unit 4. The axes of said blanket and plate cylinders 2, 3 and of a plurality of inking rollers 4a of said offset inking unit 4 are parallel to the axis of the central impression cylinder 1. Each blanket cylinder 2 is supported on a particular first support 5 and each plate cylinder 3 is supported on a particular second support 6. Said first and second supports 5, 6 are directly connected to a middle region of the main frame 1 by means of respective first and second horizontal linear guidance means 20a, 20b, 21a, 21b; 22a, 22b, 23a, 23b (described in more detail with reference to FIGS. 5, 6 and 9) and driven by driving means so that the first and second supports 5, 6 and the corresponding blanket and plate cylinders 2, 3 are individually linearly movable in horizontal directions perpendicular to the axis of the central impression cylinder 1 between respective withdraw positions, and respective multiple working positions in which the blanket and plate cylinders 2, 3 are in their withdraw positions and multiple working positions, respectively.

(15) The offset inking units 4 of all the printing stations which are located at one and the same web inlet side or web outlet side of the central impression cylinder 1 are installed on an auxiliary frame 7 which is connected at its top by third horizontal linear guidance means 24, 25 to upper beams 11 extending from the middle region of the main frame 8 and at its bottom by fourth horizontal linear guidance means 26, 27 to lower beams 12 extending from the middle region of the main frame 8 (see also FIGS. 7 and 8). Said upper and lower beams 11, 12 are rigidly connected to the main frame 8 and belong thereto. The offset inking units 4 are superposed to one another in each auxiliary frame 7 and slightly staggered following the diameter of the central impression cylinder.

(16) The auxiliary frames 7 are driven by driving means so that they are movable in horizontal directions perpendicular to the axis of the central impression cylinder 1 between respective withdraw positions in which the offset inking units 4 are in their withdraw positions (FIG. 2) and respective multiple working positions (FIG. 1) in which the offset inking units 4 are in their multiple working positions, respectively.

(17) To vary the format, i.e. the repeat length, it is necessary to replace the pairs of blanket and plate cylinders 2, 3 having a particular diameter with pairs of blanket and plate cylinders 2, 3 having a new diameter, adjust the positions of a plurality of inking rollers 4a of the offset inking units 4 to conform to the new diameter of the plate cylinder 3, and then adjust the working positions of the first and second supports 5 and auxiliary frame 7 by linearly moving them in the horizontal directions to put the blanket and plate cylinders 2, 3 and the inking rollers 4a of the offset inking unit 4 in good condition for working therebetween and with the web printable substrate B supported on the central impression cylinder 1.

(18) Although the auxiliary frame 7 could be made as one part, for manufacture easiness purposes the auxiliary frame 7 is advantageously comprised of a plurality of modular auxiliary frame parts 71-74 staked on one another, wherein each modular auxiliary frame part 71-74 carries one of the offset inking units 4, although there is no limitation for one or more of the auxiliary frame parts 71-74 to carry more than one offset inking units 4. The stacked modular auxiliary frame parts 71-74 are staggered so as to follow the circumference of the central impression cylinder 1 and connected to each other by releasable fastening means 36. Thus, the stacked modular auxiliary frame parts 71-74 forming each the auxiliary frame 7 can be moved as one unit between their withdrawn and working positions.

(19) Advantageously, although it is not essential, all the eight auxiliary frame parts 71-74 are identical design and symmetrically located with respect to a central vertical plane Cvp comprising the axis of the central impression cylinder. The arrangement of the components of the offset inking units 4 installed on the four auxiliary frame parts 71-74 located at the web inlet side is identical and the arrangement of the components of the offset inking units 4 installed on the four auxiliary frame parts 71-74 located at the web inlet side is identical, but due to the switch of the web-pass direction, downwards at the web inlet side and downwards at the web outlet side, the offset inking units 4 at the web inlet side are not internally identical to the offset inking units 4 at the web outlet side.

(20) As shown in FIG. 5, by momentarily releasing the aforementioned releasable fastening means 36, the modular auxiliary frame parts 71-74 are individually movable so that the position of one or more of said staked modular auxiliary frame parts 71-74, for example the one carrying the uppermost inking unit 4 in one or both auxiliary frames 7, can be shifted away from the central impression cylinder 1 with respect to the rest of the staked modular auxiliary frame parts 71-74 forming the auxiliary frame 7. Then the shifted modular auxiliary frame part 71-74 can be connected again to the rest of modular auxiliary frame parts 71-74 using the releasable fastening means 36 to form the auxiliary frame 7. Thus, the shifted modular auxiliary frame part 71-74 provides sufficient room for an alternative inking unit to be mounted in the corresponding printing station while the rest of modular auxiliary frame parts 71-74 are located with their offset inking units 4 in the working positions.

(21) Alternatively or additionally, one or more of the stacked modular auxiliary frame parts 71-74 on which offset inking units 4 are mounted can be replaced with dummy modular auxiliary frame parts, such as for example the dummy modular auxiliary frame part 73a shown in FIG. 11, to allow a limited number of printing stations instead of the maximum possible number and/or to allow space for additional drying or curing equipment.

(22) FIG. 1 shows the printing machine with the printing stations in one of its working positions, where the blanket cylinders 2 supported on the individual first supports 5 are rolling in contact with the web printable substrate B supported on the central impression cylinder 1, the plate cylinders 3 supported on the individual second supports 6 are rolling in contact with the corresponding blanket cylinders 2 and said plurality of inking rollers 4a of the offset inking units 4 supported on the two auxiliary frames 7 located at both web inlet side and web outlet side are rolling in contact with the corresponding plate cylinder 3. The different working positions are selected to accommodate pairs of blanket and plate cylinders 2, 3 of different diameters. For requirements of the offset printing technique, the diameter of the blanket cylinder 2 and the diameter of the plate cylinder 3 need to be identical to each other and in all the printing stations, so that said diameter determines the printing repeat length on the web printable substrate B.

(23) FIG. 2 shows the printing machine with the printing stations in the withdrawn positions, in which the blanket cylinder 2 of each printing station is away from the central impression cylinder 1, the plate cylinder 3 is away from the blanket cylinder 2 and the offset inking unit 4 is away from the plate cylinder 3. When the offset inking units 4 are in their working positions, the auxiliary frames 7 are spaced apart from the first and second supports 5, 6 enough to permit easy access of an operator between the auxiliary frames 7 and the first and second supports 5, 6 irrespective of the withdrawn or working positions of the first and second supports 5, 6 and the diameter of the pairs of blanket and plate cylinders 2, 3 installed thereon. Thus, the operator in charge of inspection or maintenance has a clear access to the rollers and other components of the offset inking units 4 and to the blanket and plate cylinders 2, 3 of all the printing stations located at the corresponding web inlet side or web outlet side.

(24) FIG. 3 shows the first and second supports 5, 6 carrying the respective blanket and plate cylinders 2, 3 in the first and the second offset printing stations with respect to the movement direction of the web printable substrate (at the upper part of the web inlet side), in a first working position adjusted to accommodate and work with pairs of blanket and plate cylinders 2, 3 having the minimum admissible diameter for a minimum repeat length.

(25) FIG. 4 shows the same components of the first and the second offset printing stations in a second working position in which the respective first and second supports 5, 6 are positioned in a second working position to accommodate and work with pairs of blanket and plate cylinders 2, 3 having the maximum admissible diameter for a maximum repeat length. The first and second supports 5, 6 can be placed in any intermediate working position between said first and second working positions to accommodate and work with pairs of blanket and plate cylinders 2, 3 of intermediate diameters. The auxiliary frame 7 and corresponding offset inking units 4 are omitted from FIGS. 3 and 4 for clarity.

(26) Although it is not essential, in the exemplary embodiment shown in the Figures, the first supports 5 and the second supports 6 of all the eight printing stations are advantageously identical design and symmetrically positioned both with respect to a central horizontal plane Chp and to a central vertical plane Cvp both comprising the axis of the central impression cylinder 1. Therefore, the first and second offset printing stations shown in FIGS. 3 and 4 are representative of the rest of the printing stations in regard of the effects of the horizontal positioning linear movements of their first and second supports 5, 6 and the relative positions of the central impression cylinder 1, blanket cylinder 2 and plate cylinder 3 for different formats.

(27) As shown in FIGS. 3 and 4, in each printing station a first horizontal plane Hp1 in which the axis of the blanket cylinder 2 is moved by the first support 5 is nearer from said central horizontal plane Chp than a second horizontal plane Hp2 in which the axis of the plate cylinder 3 is moved by the second support 6. This means that the axis of the blanket cylinder 2 and the axis of the plate cylinder 3 are comprised in a common inclined first plane P1 when the pair of blanket and plate cylinders 2, 3 are in a working position and for any diameter thereof between said minimum and maximum diameters. The inclination degree of said first plane P1 varies with the diameter of the pair of blanket and plate cylinders 2, 3 due to the linear positioning movement of the first and second supports 5, 6 in the different first and second horizontal planes Hp1, Hp2.

(28) Owing to the arrangement of the printing stations around the central impression cylinder, in each printing station the axis of the central impression cylinder 1 and the axis of the blanket cylinder 2 are comprised in a common inclined second plane P2 when the blanket cylinder 2 is in a working position and for any diameter thereof between said minimum and maximum diameters. The inclination degree of said second plane P2 varies depending on the farther or nearer position of the corresponding printing station with respect to said central horizontal plane Chp and on the diameter of the blanket cylinder 2 due to the linear positioning movement of the first support 5 in the first horizontal plane Hp1.

(29) In order to reduce or minimize the effect produced by the gap-bounce in the quality of printing, the design of the first and second supports 5, 6 and the arrangement thereof in all of the printing stations is selected such that an angle A between the first and second planes P1, P2 does not exceed 20 regardless the position of the corresponding printing station with respect to the central horizontal plane Chp and for any diameter of the pair of blanket and plate cylinders 2, 3 installed therein between a minimum diameter (FIG. 3) and a maximum diameter (FIG. 4). Said angle A ranging from 0 to 20 and more preferably from 0 to 15 is considered to be acceptable in regard of the gap-bounce effect because it does not produce an appreciable negative consequence in the quality of printing.

(30) By way of illustration only, in the particular embodiment shown in the Figures said angle A for the printing stations farthest from the central impression cylinder 1 ranges from 3.42 for the minimum format (FIG. 3) to 11.58 for the maximum format (FIG. 4), with an intermediate working position for a particular intermediate format (not shown) where the angle A is 0, i.e. the axis of the central impression cylinder 1, blanket cylinder 2 and plate cylinder 3 are comprised in one and the same plane. The angle A for the printing stations nearer from the central impression cylinder 1 ranges from 11.56 for the minimum format (FIG. 3) to 1.51 for the maximum format (FIG. 4).

(31) There is an exception when a printing station (not shown) is optionally positioned such that the axes of the blanket and the plate cylinders are both moved by the respective first and second supports in the central horizontal plane Chp comprising the axis of the central impression cylinder 1. In this case, the aforementioned first and second planes are a common horizontal plane and the angle therebetween is 0 for all working positions of the pair of blanket and plate cylinders and for any diameter thereof between said minimum and maximum diameters, which is an ideal situation in regard of the gap-bounce effect.

(32) As best shown in FIGS. 6, 7 and 8, the aforementioned main frame 8 of the printing machine comprises an operator side main frame wall 8a and a gear side main frame wall 8b respectively located at a gear side and an operator side of the printing machine adjacent opposite ends of the central impression cylinder 1. Said operator side and gear side main frame walls 8a, 8b have respective middle regions on which the central impression cylinder 1 is rotatingly supported and operator side and gear side upper and lower beams 11a, 11b; 12a, 12b horizontally extending from said middle regions of the operator side and gear side main frame walls 8a, 8b and solidly connected thereto. On the gear side main frame wall 8b there is supported a main motor 28 connected for rotating the central impression cylinder 1 and at the operator side main frame wall 8a there is supported a brake 29 connected for braking the central impression cylinder 1. The operator side of the printing machine is shown in FIGS. 1-5 and 9.

(33) As shown in FIG. 6, each of the first supports 5 carrying one blanket cylinder 2 comprises an operator side first support 5a and a gear side first support 5b carrying respective support means 34a, 34b such as roll bearings or the like for rotatingly supporting a blanket mandrel 2a on which a blanket sleeve 2b (depicted with phantom lines in FIG. 6) is mounted. Said blanket mandrel 2a and blanket sleeve 2b form together the corresponding blanket cylinder 2. The support means 34b at the gear side first support 5b are capable of supporting said mandrel in cantilever and the support means 34a at the operator side first support 5a can be opened and spaced apart by individually moving the operator side first support 5a for enabling the blanket sleeve 2b to be axially installed or removed from the blanket mandrel 2a through the machine operator side (as shown in the left side of FIG. 6). A blanket cylinder-driving servomotor 13 is carried on said gear side first support 5b and connected for driving the rotating movement of the blanket cylinder 2.

(34) The operator side first support 5a is directly connected to the middle region of the operator side main frame wall 8a by linear guidance means comprising, for example, two parallel linear rails 20a attached to the operator side main frame wall 8a and corresponding slides 21a attached to the operator side first support 5a and slidingly connected to said linear rails 20a. A gear side first support-driving motor 15a, such as a servomotor, is supported on the operator side main frame wall 8a and connected to rotate a roller screw spindle 30a coupled to a nut 31a attached to the operator side first support 5a. Said roller screw spindle 30a is parallel to the two linear rails 20a and located between both (see also FIG. 8).

(35) In a similar way, the gear side first support 5b is directly connected to the middle region of the gear side main frame wall 8b by linear guidance means comprising, for example, two parallel linear rails 20b attached to the gear side first support 5b and corresponding slides 21b attached to the gear side main frame wall 8b and slidingly connected to said linear rails 20b. A gear side first support-driving motor 15b, such as a servomotor, is supported on the gear side main frame wall 8b and connected to rotate a roller screw spindle 30b coupled to a nut 31b attached to the gear side first support 5b. Said roller screw spindle 30b is parallel to the two linear rails 20b and located between both (see also FIG. 8).

(36) The operator side and gear side first support-driving motors 15a, 15b can be individually activated to move the operator side and gear side first supports 5a, 5b either in unison for shifting the blanket cylinder 2 between the withdrawn and working positions or independently from one another, for example for enabling a change of format or for cylinder's relative positioning adjustment.

(37) Similarly, as shown in FIG. 7, each of the second supports 6 carrying one plate cylinder 3 comprises an operator side second support 6a and a gear side second support 6b carrying respective support means 35a, 35b such as roll bearings or the like for rotatingly supporting a plate mandrel 3a on which a plate sleeve 3b (depicted with phantom lines in FIG. 7) is mounted. Said plate mandrel 3a and plate sleeve 3b form together the corresponding plate cylinder 3. The support means 35b at the gear side second support 6b are capable of supporting said mandrel in cantilever and the support means 35a at the operator side second support 6a can be opened and spaced apart by individually moving the operator side second support 6a for enabling the plate sleeve 3b to be axially installed or removed from the plate mandrel 3a through the machine operator side (as shown in the left side of FIG. 7). A plate cylinder-driving servomotor 14 is carried on said gear side second support 6b and connected for driving the rotating movement of the plate cylinder 3.

(38) The operator side second support 6a is directly connected to the middle region of the operator side main frame wall 8a by linear guidance means comprising, for example, two parallel linear rails 22a attached to the operator side second support 6a and corresponding slides 23a attached to the operator side main frame wall 8a and slidingly connected to said linear rails 22a. A gear side second support-driving motor 16a, such as a servomotor, is supported on the operator side main frame wall 8a and connected to rotate a roller screw spindle 32a coupled to a nut 33a attached to the operator side second support 6a. Said roller screw spindle 32a is parallel to the two linear rails 22a and located between both (see also FIG. 8).

(39) In a similar way, the gear side second support 6b is directly connected to the middle region of the gear side main frame wall 8b by linear guidance means comprising, for example, two parallel linear rails 22b attached to the gear side second support 6b and corresponding slides 23b attached to the gear side main frame wall 8b and slidingly connected to said linear rails 22b. A gear side second support-driving motor 16b, such as a servomotor, is supported on the gear side main frame wall 8b and connected to rotate a roller screw spindle 32b coupled to a nut 33b attached to the gear side second support 6b. Said roller screw spindle 32b is parallel to the two linear rails 22b and located between both (see also FIG. 8).

(40) The operator side and gear side second support-driving motors 16a, 16b can be individually activated to move the operator side and gear side second supports 6a, 6b either in unison for shifting the plate cylinder 3 between the withdrawn and working positions or independently from one another, for example for enabling a change of format or for cylinder's relative positioning adjustment.

(41) FIGS. 9 and 10, together with FIG. 5, show the construction of the auxiliary frame 7. There is shown the operator side and gear side main frame walls 8a, 8b of the main frame 8 supporting the central impression cylinder 1, the first support 5 carrying the blanket cylinder 2, the second support 6 carrying the plate cylinder 3, and the auxiliary frame 7 carrying the offset inking units 4. At the gear side of the auxiliary frame 7 motors 39 are arranged for rotating the inking rollers 4a and other rollers of the offset inking units 4. The auxiliary frame 7 at the web outlet side is similar to that at the web inlet side.

(42) The auxiliary frame 7, which in the illustrated embodiment is formed by the auxiliary frame parts 71-74 connected to each other, is attached at its operator side to operator side upper and lower auxiliary frame-carriers 75a, 76a respectively connected by operator side upper and lower horizontal linear guidance means 24a, 25a; 26a, 27a to operator side upper and lower beams 11a, 12a extending from the middle region of the operator side main frame wall 8a of the main frame 8 (see also FIG. 5). Similarly, the auxiliary frame 7 is attached at its gear side to gear side upper and lower auxiliary frame-carriers 75b connected by third gear side upper and lower horizontal linear guidance means 24b, 25b respectively to the gear side upper and lower beams 11b, 12b extending from the middle region of the gear side main frame wall 8a of the main frame 8.

(43) Said operator side upper and lower horizontal linear guidance means comprise two parallel upper linear rails 24a and two parallel lower linear rails 26a respectively attached to the corresponding operator side upper and lower beams 11a, 12a, and upper and lower slides 25a, 27a which are attached to the corresponding operator side upper and lower auxiliary frame-carriers 75a, 76a and slidingly connected to said upper and lower linear rails 24a, 26a, respectively. Operator side auxiliary frame-driving motors 17a, such as servomotors, are supported on the operator side upper and lower beams 11a, 12a and connected to rotate respective roller screw spindles 37a coupled to respective nuts 38a attached to the corresponding operator side upper and lower auxiliary frame-carriers 75a, 76a, said roller screw spindles 37a being parallel to the corresponding two parallel upper and lower linear rails 24a, 26a and located between both.

(44) Similarly, Said gear side upper and lower horizontal linear guidance means comprise two parallel upper linear rails 24b and two parallel lower linear rails 26b respectively attached to the gear side upper and lower beams 11b, 12b, and gear side upper and lower slides 25b, 27b which are attached to the corresponding gear side upper and lower auxiliary frame-carriers 75b and slidingly connected to said gear side upper and lower linear rails 24b, 26b, respectively. Gear side auxiliary frame-driving motors 17b, such as servomotors, are supported on the gear side upper and lower beams 11b, 12b and connected to rotate respective roller screw spindles 37a coupled to respective nuts 38b attached to the corresponding gear side upper and lower auxiliary frame-carriers 75b, said roller screw spindles 37b being parallel to the corresponding two parallel upper and lower linear rails 24b, 26b and located between both.

(45) By activating in unison the operator side and gear side auxiliary frame-driving motors 17a, 17b, the four auxiliary frame-carriers 75a, 76a are moved together for shifting the auxiliary frame 7 formed by the auxiliary frame parts 71-74 and the offset inking units 4 installed thereon between the withdrawn and working positions. When some of the releasable fastening means 36 are released, by activating only the upper or lower auxiliary frame-driving motors 17a, 17b corresponding to one of the auxiliary frame 7 located at the machine web inlet or web outlet side it is possible to shift the position of one or more auxiliary frame parts 71-74 with respect to the rest of them in the stack.

(46) The scope of the present invention is defined in the attached claims.