Printing press

Abstract

 An improved printing press (10) has a plurality of printing units (12, 14, 16, 18) which are operable to sequentially print on opposite sides of a web. A drive assembly (22) is iprovided for transmitting force to rotate print cylinders in each of the printing units. The drive assembly (22) includes a drive line (26) which extends along the printing units. The drive line (26) is formed by a plurality of rotatable and axially aligned drive shafts which are interconnected by coupling units. The coupling units are resiliently flexible to accommodate axial movement between the drive shaft without interrupting rotation of print cylinders. A gear train (84) is associated with each of the printing units to transmit power from the drive line to the printing unit. A phase control assembly (106) is provided to incrementally rotate the printing cylinders in one printing unit relative to the printing cylinders in the other printing unit to obtain the desired registration between the images printed by the printing units.

Description

Background of the Invention

[0001] The present invention relates to a printing press having a plurality of printing units and a control apparatus for adjusting the phase relationship between the printing units.

[0002] Known web offset printing presses have a plurality of printing units which are driven from a common drive line. Various phase adjustment control assemblies have been provided to effect incremental rotation of the printing cylinders in one unit relative to the printing cylinders in the other units to obtain the desired registration between images printed on the web by the printing units. These phase adjustment control assemblies have frequently been relatively complicated in construction and difficult to manufacture and install in a printing press.

[0003] It has been suggested, in U.S. Patent No. 2,863,387, that a printing press drive line have a separate drive worm for each unit of the printing press. In order to effect phase adjustment of the cylinders in the printing unit, this patent suggests that the worm and the drive shaft to which it is connected be axially moved to incrementally rotate a worm wheel and printing cylinders. Collars have been associated with the drive shaft to which the worm is connected to accommodate axial movement of the drive shaft.

Summary of the Present Invention

[0004] The present invention relates to a new and improved printing press having a plurality of printing units which are operable to sequentially print on a web. Each of the printing units includes rotatable print cylinders which engage the web. A drive assembly is provided to transmit force to rotate the printing cylinders in the printing units.

[0005] The drive assembly includes a drive line having a plurality of axially aligned drive shafts interconnected by coupling units which are resiliently flexible to accommodate axial relative movement between the drive shafts without interrupting rotation ot the printing cylinders. A gear train is provided to transmit power from the drive line to the printing units. The gear train includes a worm which is disposed in meshing engagement with a worm wheel. The worm is fixedly connected with one of the drive shafts.

[0006] An improved phase adjustment control assembly is operable to incrementally rotate the printing cylinders in one printing unit relative to the printing cylinders in another printing unit to thereby obtain a desired relationship between images printed by the printing units. This is accomplished by axially moving the worm and drive shaft for the printing unit. The axial movement of the printing unit drive shaft resiliently flexes at least one of the coupling units without interrupting operation of the printing press.

[0007] Accordingly, it is an object of this invention to provide a new and improved printing press having a drive line with a plurality of drive shafts which are interconnected by resiliently flexible coupling units to accommodate axial movement between drive shafts in the drive line to enable the drive shafts to be axially moved by a phase adjustment control assembly.

Brief Description of the Drawings

[0008] The foregoing and other objects and features of the present invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:

Fig. 1 is a schematic plan view of a printing press constructed in accordance with the present invention and illustrating the relationship between a plurality of printing units and a drive line for transmitting force to drive the printing units;

Fig. 2 is an enlarged fragmentary sectional view illustrating the relationship between an input drive shaft and a plurality of coupling units in the drive line of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view illustrating the relationship between a printing unit drive shaft disposed in the drive line of Fig. 1 and a phase adjustment control assembly;

Fig. 4 is an enlarged fragmentary sectional view illustrating the relationship between an intermediate drive shaft in the drive line of Fig. 1 and a pair of coupling units;

Fig. 5 is a fragmentary sectional view of a gear train which transmits drive forces from the printing unit drive shaft of Fig. 3 to the printing cylinders in a printing unit;

Fig. 6 is an enlarged fragmentary sectional view of the phase adjustment control assembly of Fig. 3;

Fig. 7 is an enlarged sectional view of a coupling unit in the drive line of Fig. 1, the coupling unit being shown in an initial or undeflected condition;

Fig. 8 is a sectional view, generally similar to Fig. 7, illustrating the manner in which the coupling unit is resiliently deflected by axial movement of the end of one drive shaft away from the end of another drive shaft; and

Fig. 9 is a sectional view, generally similar to Figs. 7 and 8, illustrating the manner in which the unit is resiliently deflected by axial movement of the end of one drive shaft toward the end of another drive shaft.

Description of One Specific Preferred Embodiment of the Invention

[0009] A four unit web offset printing press 10 constructed in accordance with the present invention is. illustrated in Fig. 1. The press 10 is a multi-color (four colors) lithographic offset printing press having four printing units 12, 14, 16 and 18. Each unit may be used to print on opposite sides of a web, paper or other material. If desired, one or more of the printing units may be thrown off or disabled in a known manner and the web printed on with the remaining units.

[0010] The printing units 12-18 are driven by a common drive assembly 22. The drive assembly 22 includes a motor 24 which is connected with a drive line 26 by a belt 28. The drive line 26 extends along one side of the printing press 10 and is connected with each of the printing units 12-18. In addition, the drive line 26 is connected with a dryer, chill rolls and a folder (not shown) disposed downstream of the printing press 10.

[0011] The drive line 26 includes a plurality of drive shafts which are interconnected by coupling units. An input drive shaft 32 is connected to a sheave 34 (Fig. 2) which is driven by the belt 28. In order to accommodate axial expansion and contraction of the input drive shaft 32, it is supported by a fixed pillow block 38 and a stationary pillow block 40 by suitable bearings 42 and 44.

[0012] Rotation of the input drive shaft 32 is transmitted through coupling units 46 and 48 to printing unit drive shafts 50 and 52 for the printing units 14 and 16 (Figs. 1 and 3). Intermediate drive shafts 54 and 56 transmit power from the printing unit drive shafts 50 and 52 for the printing units 14 and 16 to printing unit drive shafts 58 and 60 for the printing units 12 and 18 (Figs. 1 and 4). Thus, the printing unit drive shafts 50 and 52 are connected with the intermediate drive shafts 54 and 56 by coupling units 64 and 66. The intermediate drive shafts 54 and 56 are in turn connected with the printing unit drive shafts 58 and 60 by coupling units 68 and 70.

[0013] The drive shaft 58 for the printing unit 12 (Fig. is connected through a coupling unit 62 with a suitable fixed bearing assembly which supports a shaft end section 74. The drive shaft 60 for the printing unit 18 is connected with a chill roll unit (not shown) through timing belt sprockets 78 and 80 which are disposed from each other by a timing belt XX. The timing belt sprocket 78 is axially movable, through a limited distance, relative to the timing belt sprocket. The chill roll unit is located after dryer 78 in the press line.

[0014] A gear train or assembly 84 (see Fig. 5) transmits drive forces from the drive line 26 to the printing unit 16 (see Fig. 1). The gear train 84 includes a worm 88 (see Fig. 3) which is integrally formed as one piece with the printing unit drive shaft 52. The worm 88 is disposed in a coaxial relationship with the common axis of rotation of the printing unit drive shaft 52 and drive line 26. The worm 88 is disposed in meshing engagement with a worm wheel 92 (see Fig. 5).

[0015] The worm wheel 92 is connected with a lower blanket cylinder gear 94 through a clutch assembly 96. The lower blanket cylinder gear 94 is fixedly connected with a lower blanket cylinder 98 and is disposed in meshing engagement with an upper blanket cylinder gear 100. The upper blanket cylinder gear 100 is fixedly connected with an upper blanket cylinder 102 which cooperates with the lower blanket cylinder 98 to define a nip through which a web passes. The manner in which the worm 88 is drivingly connected with the blanket and plate cylinders of the printing unit 16 is generally the same as is described in U.S. Patent No. 3,606,800 and will not be further described herein in order to avoid prolixity of description. Although only the gear train 84 for the printing unit 16 is shown in Fig. 5, it should be understood the printing units 12, 14 and 18 have similar gear trains.

[0016] Experience has shown that during operation of the printing press 10, it will be necessary to adjust the phase of the printing units 12-18 relative to each other in order to obtain a desired registration between images printed on the web by the printing units. In order to adjust the phase of one printing unit relative to the other printing units, a phase adjustment control assembly in each of the printing units 12-18 is selectively operable to effect incremental rotation of the printing cylinders in the associated printing unit relative to the printing cylinders in the other printing units. Thus, a phase adjustment control assembly 106 for the printing unit 16 (see Figs. 3 and 6) includes a worm or input gear 110. The worm 110 is driven by a reversible motor (not shown). Rotation of the worm 110 rotates an annular worm wheel 114 (Fig. 6) about the common axis of the printing unit drive shaft 52 and the drive line 26. The drive shaft 52 extends through the center of the worm wheel 114 so that the worm wheel circumscribes the drive shaft.

[0017] Rotation of the worm wheel 114 results in axial movement of printing unit drive Shaft 52. Thus, upon rotation of the worm wheel 114 and an annular plate 118 fixedly connected to the worm wheel, internal threads 120 on the plate and worm wheel cooperate with external threads on a carriage 124 to move the carriage axially. The printing unit drive shaft 52 is rotatably mounted on and held against axial movement relative to the carriage 124 by a bearing assembly 128. The worm wheel 114 and plate 118 are held against axial movement by a housing 132 which is fixedly connected to a frame 134 of the printing unit 16.

[0018] Rotation of the worm wheel 114 and plate 118 in one direction results in the threads 120 and 122 interacting to shift the carriage 124 and printing unit drive shaft 52 toward the left (as viewed in Fig. 6). Similarly, rotation of the worm wheel in the opposite direction results in the threads 120 and 122 interacting to shift the carriage 124 and printing unit drive shaft 52 toward the right (as viewed in Fig. 6). The carriage 124 is held against rotation relative to the printing unit frame 134 by a suitable slot and key arrangement. Since the annular worm wheel 114 is coaxial with the printing unit drive shaft 52, the internal and external threads 120 and 122 cause the carriage 124 to transmit a force component parallel to the axis of the printing unit drive shaft 52 so that the carriage 124 can move with a minimum tendency to bind or jam.

[0019] Upon movement of the printing unit drive shaft 52 through its range of movement toward either the left or right, an actuator arm 138 is effective to actuate a limit switch 140 or 142 to interrupt operation of the reversible motor which drives the input worm 110. In one specific instance, the printing unit drive shaft 52 had a range of movement of 0.150 inches toward either the right or the left from the centered or initial position shown in Fig. 6. When the worm 110 stops rotating, the worm wheel and carriage are effective to hold the printing unit drive shaft 52 against axial movement.

[0020] The coupling units 46, 48, 62, 64, 66, 68 and 70 are resiliently flexible to accommodate axial movement of printing unit drive shafts 50, 52, 58 and 60. Thus, upon movement of the printing unit drive shaft 52 toward the right (as viewed in Figs. 1 and 3) the coupling unit 48 is resiliently flexed from the initial or undeflected condition of Fig. 7 to the deflected condition ot Fig. 8. Similarly, upon movement of the printing unit drive shaft 52 toward the left (as viewed in Figs. 1 and 3), the coupling unit 48 is flexed from the initial condition of Fig. 7 to the deflected condition of Fig. 9.

[0021] The coupling unit 48 includes a left (as viewed in Figs. 7-9) hub 150 which is fixedly connected to one end of the input drive shaft 32 (see Fig. 2). A second hub 152 is fixedly connected to the printing unit drive shaft 52. A circular center ring 154 is disposed midway between the two hubs 150 and 152 (see Fig. 7), A pair of disc packs 156 and 158 are connected with the hubs 150 and 152 by suitable bolts 160. The disc packs 156 and 158 are connected with the center ring 154 by a pair of mounting assemblies 164 (only one of which is shown in Figs. 7-9). The mounting assembly 164 includes a bolt 166 and spacers 168 and 170. Although only one mounting assembly 164 has been shown in Figs. 7-9, it should be understood that two mounting assemblies 164 are provided between the center ring 164 and the disc packs 156 and 158 at 180° offset locations around the center ring 154.

[0022] The disc packs 156 and 158 are formed of resilient annular metal discs. Upon axial movement of a printing unit drive shaft 52 to effect a phase adjustment between the printing units, the metal discs are resiliently flexed from their initial straight condition shown in Fig. 7 to either the deflected condition shown in Fig. 8 or the deflected condition shown in Fig. 9 depending upon the direction of movement of the printing unit drive shaft. The couplings 46, 48, 62, 64, 66, 68 and 70 all have the similar construction and are commercially available from Thomas Coupling Division, of Rex Chain Belt Inc., Warren, Pennsylvania, U.S.A. Couplings 46 and 48 are type DBZ and couplings 62, 64, 66, 68, and 70 are type 71-X.

[0023] In view of the foregoing description, it is apparent that the present invention relates to a new and improved printing press 10 having a plurality of printing units 12-18 which are operable to sequentially print on a web. Each of the printing units includes rotatable blanket cylinders 98 and 102 engage the web. A drive assembly 22 is provided to transmit force to rotate the printing cylinders in the printing units.

[0024] The drive assembly 22 includes a drive line 26 having a plurality of axially aligned drive shafts 50-60 interconnected by identical coupling units 46, 48, 64-70 which are resiliently flexible to accommodate axial relative movement between the drive shafts without interrupting rotation of the printing cylinders. A gear train 84 is provided in each printing unit to transmit power from the drive line 26 to the printing units. The gear train 84 includes a worm 88 which is disposed in meshing engagement with a worm wheel 92. The worm 88 is fixedly connected with one of the printing unit drive shafts 50, 52, 58 or 60.

[0025] A phase adjustment control assembly 106 is operable to incrementally rotate the printing cylinders 98, 102 in one printing unit 16 relative to the printing cylinders in another printing unit to thereby obtain a desired relationship between images printed by the printing units. This is accomplished by axially moving the worm 88 and drive shaft 52 for the printing unit 16. The axial movement of the printing unit drive shaft 52 resiliently flexes the coupling units 48 and 66 without interrupting operation of the printing press 10. Similarly, axial movement of the drive shaft 58 for the printing unit 12 flexes the coupling units 62 and 68, axial movement of the drive shaft 50 for the printing unit 14 flexes the coupling units 64 and 46, and axial movement of the drive shaft 60 for the printing unit 18 flexes the coupling unit 70 and shifts the spur gear 78 axially relative to the spur gear 80.

Claims

1. A printing press comprising a plurality of printing units operable to sequentially print on material, each of said printing units including a rotatable print cylinder which engages the material, drive means for transmitting force to rotate the print cylinders, said drive means including a drive line having a plurality of rotatable and axially aligned drive shafts drivingly interconnected by a plurality of coupling units which are resiliently flexible to accommodate axial relative movement between said drive shafts without interrupting rotation of said print cylinders, and gear means for transmitting power from said drive line to said printing units, said gear means including a worm disposed in meshing engagement with a worm wheel,'said worm being coaxial with and rotatable by one of said drive shafts, said worm being fixedly connected with said one drive shaft for axial movement therewith relative to an adjacent drive shaft, and control means for incrementally rotating the print cylinder in one printing unit relative to the print cylinder in another printing unit, said control means including means for moving said one drive shaft and said worm axially relative to an adjacent drive shaft to flex at least one of said coupling units.

2. A printing press as set forth in claim 1 wherein said coupling means includes a first mounting section fixedly connected to an end portion of said one drive shaft, a second mounting section fixedly connected to an end portion of another drive shaft, and resiliently deflectable force transmitting means extending between said first and second mounting sections for accommodating axial movement of said one drive shaft toward and away from said other drive shaft.

3. A printing press as set forth in claim 1 wherein said worm wheel circumscribes said one drive shaft and is rotatable by said worm to move said one drive shart axially.

Drawing