Anti-bounce print deck for flexographic printing press

Abstract

A device and a method is disclosed to maintain plate and anilox mandrel position stability in print decks of a flexographic printing press. In one aspect, the mandrel bearings associated with at least one of the plate roll and the anilox roll are preloaded for the purpose of eliminating backlash and increasing the positional stiffness of the bearings, and thus the mandrel. In another aspect, the roll drive motor control system is enabled to provide a torque additive command the torque profile to maintain rotational consistency and otherwise overcome torque transients experienced by the motor during print bounce. Accordingly, the problem commonly referred to as print bounce and or print banding is alleviated.

Claims

1. A printing press comprising: front and back frames; a front bearing assembly supported on the front frame; a back bearing assembly supported on the back frame; a roll extending axially between the front and back frames, the roll having front and back ends which are rotatably supported by the front and back bearing assemblies, the roll comprising one of an anilox roll and a plate roll; and a motor operatively connected with and adapted and configured for rotating the roll, the motor having a control, the control being configured to determine rotational position information of the roll, the control being enabled to drive the motor with a torque profile based upon the rotational position of the roll, the control being enabled to apply an additive torque command to the torque profile based upon the rotational position of the roll to compensate for a torque transient subjected to the motor by a periodic disturbance during rotation of the roll.

2. The printing press of claim 1 wherein the control is adapted and configured to: process rotational position data of the roll relative to an occurrence of the torque transient during rotation of the roll, and apply the additive torque command to the torque profile prior to the occurrence of the torque transient.

3. The printing press of claim 1 wherein the control is adapted and configured to process rotational position data of the roll relative to an occurrence of the torque transient during rotation of the roll during set-up of the printing press prior to normal operation of the printing press.

4. The printing press of claim 1, wherein the control is adapted and configured to apply the additive torque command in a manner to reduce a peak to peak torque transient.

5. The printing press of claim 1, further comprising an encoder coupled to the motor, the encoder providing the rotational position information of the roll to the control.

6. The printing press of claim 1, wherein the additive torque command applied to the torque profile to compensate for the torque transient subjected to the motor by the periodic disturbance during rotation of the roll is directed to the periodic disturbance generated by the printing plate used in the press.

7. A control for driving a motor for a roll in a printing press, wherein the printing press has front and back frames, a front bearing assembly supported on the front frame, and a back bearing assembly supported on the back frame, the roll extends axially between the front and back frames, the roll has front and back ends which are rotatably supported by the front and back bearing assemblies, the roll comprises one of an anilox roll and a plate roll, and the motor is operatively connected with and adapted and configured for rotating the roll, the control being configured to: (i) determine rotational position information of the roll, (ii) drive the motor with a torque profile based upon the rotational position of the roll, and (iii) apply an additive torque command to the torque profile to compensate for a torque transient subjected to the motor by a periodic disturbance during rotation of the roll.

8. The control of claim 7 wherein the control is adapted and configured to: (iv) process rotational position data of the roll relative to an occurrence of the torque transient during rotation of the roll, and (v) apply the additive torque command to the torque profile prior to the occurrence of the torque transient.

9. The control of claim 8 wherein the control is adapted and configured to: process rotational position data of the roll relative to the occurrence of the torque transient during rotation of the roll during set-up of the printing press prior to normal operation of the printing press.

10. The control of claim 7, wherein the control is adapted and configured to: (iv) apply the additive torque command in a manner to reduce a peak to peak torque transient.

11. The control of claim 7, wherein the control is adapted and configured to: (iv) be operatively coupled to an encoder associated with the motor to receive the rotational position information of the roll.

12. The control of claim 7, wherein control is adapted and configured to: (iv) apply the additive torque command to the torque profile to compensate for the torque transient subjected to the motor by the periodic disturbance during rotation of the roll based upon the periodic disturbance generated by the printing plate used in the press.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a is a cross-sectional view of a mandrel for an anilox roll or plate roll engaged in an exemplary bearing assembly of a deck of a press.

(2) FIG. 1b is a partial side view of a front frame of the deck of the press with a mandrel engaged in a bearing assembly as shown in FIG. 1a wherein the mandrel may be for both a plate roll and anilox roll.

(3) FIG. 1c is partial top view of a back frame of the deck of the press showing the plate roll and anilox roll with plate roll shifted axially and the mandrel of the plate roll engaged in a bearing assembly similar to that shown in FIG. 1a.

(4) FIG. 2 is an end view schematic diagram of a lever actuator for radially loading a second bearing support of the bearing assembly of FIG. 1a.

(5) FIG. 3 is an end view schematic diagram of a pivot actuator for radially loading the second bearing support of the bearing assembly of FIG. 1a.

(6) FIG. 4 is a control diagram for an exemplary control of a drive of a motor of an exemplary roll.

(7) FIG. 5 is a plot of torque transients caused by print bounce without a torque assist command signal activated in the control of the drive of the motor of an exemplary roll, wherein the plot shows following error disturbance in thousandths of inches (y-axis) over time (x-axis).

(8) FIG. 6 is a plot of torque transients caused by print bounce with a torque assist command activated in the control of the drive of the motor of the exemplary roll of FIG. 5 wherein the plot shows following error disturbance in thousandths of inches (y-axis) over time (x-axis).

DETAILED DESCRIPTION

(9) By way of example and not in any limiting sense, as described in U.S. Pat. Nos. 6,142,073 and 6,176,181, the printing press may have front and back frames FF,FB, and anilox rolls AR, and plate rolls PR extending between the frames for each deck. An ink fountain (not shown) on the deck supplies ink to the anilox roll AR, and the anilox roll transfers the ink to the plate roll PR. The plate roll PR prints an image on the web as the web is moved past the plate roll. Both the anilox roll AR and the plate roll PR have a center axis RA along their lengths and include a front end which is rotatably supported in a front bearing assembly FBA and a back end which is rotatably supported in a back bearing assembly BBA. Each of the front and back bearing assemblies FBA,BBA for each roll AR,PR may be mounted in a corresponding bearing block FBB,BBB. Thus, each deck may include a plate roll and an anilox roll, each of which may be supported by bearing blocks FBB,BBB that in turn may be operatively mounted to the front and back frames FF,BF of the press in a manner to allow the rolls to shift axially in the direction of the roll axis RA for sleeve change out, and roll maintenance and removal, as needed.

(10) The front bearing assembly FBA for each roll AR,PR may be mounted to a front bearing block FBB, which is attached to a front carriage FC. Upper and lower linear bearings ULB,LLB may be attached to the front carriage FC, and the upper and lower linear bearings ULB,LLB may be slidably mounted on parallel spaced-apart upper and lower linear rails UR,LR of the front frame FF. The front carriage FC may move in a direction perpendicular to the roll axis RA to allow access to the sleeve and sleeve removal after the roll has been axially shifted and withdrawn from the front bearing assembly FBA.

(11) The back end of the roll is rotatably supported by a back bearing assembly BBA in a back bearing block BBB, which is connected to the back frame BF. The back bearing assembly BBA for each roll AR,PR may be mounted to a back bearing block BBB which is attached to a bracket that is adjustably and operatively connected to the back frame BF. The rolls may be driven by a drive motor DM. The back bearing block BB for each roll AR,PR may be mounted on an axial shift mechanism ASM, which shifts the back bearing block BBB and the corresponding roll in the axial direction of the roll axis RA. The back bearing block BBB and drive motor DM may be supported by the bracket, and the bracket may be slidably mounted by linear bearings on rails which extend parallel to the center axis RA of the roll. The rails may be supported by the back frame BF. The bracket and the corresponding roll may be shifted forwardly and backwardly in directions parallel to the axis RA of the roll by a linear actuator of the axial shift mechanism ASM. The linear actuator may extend between the bracket and the back frame. The drive motor DM may move with the bracket via the linear actuator. While the drawings show an axial shift mechanism ASM for the rolls, the axial shift mechanism may be omitted. Additionally, while the drawings show a multi-deck printing press, the principles of the disclosure may also be used with other types of presses and can be used on presses which have only one print deck.

(12) For purposes of ease of illustration, FIG. 1a presents the front bearing assembly FBA for the mandrel 1 which may be for either the plate roll PR or the anilox AR, and the front bearing block FBB has been omitted. The back bearing assembly BBA for the mandrel may have a similar configuration and is not shown for the sake of brevity. As discussed above, the mandrel 1 may comprise a round shaft type component which supports a corresponding plate or anilox sleeve 2 with the plate or anilox sleeve mounted on mandrel.

(13) Referring to FIG. 1a, the bearing assembly (e.g., the FBA,BBA) comprises a first bearing support 3 and a second bearing support 4. The first bearing support 3 may be a roller bearing and may be rigidly mounted to the respective bearing block (for instance, the front bearing block FBB or back bearing block BBB). As described in the example above, the respective bearing block (e.g., FBB,BBB) is directly connected to linear slides and ball screw positioning devices, for instance, those of the type set forth in U.S. Pat. Nos. 6,142,073 and 6,176,181. In the bearing assembly FBA,BBA, the second bearing support 4 may be disposed adjacent to the first bearing support 3. The second bearing support 4 may also comprise a roller bearing. Rotational elements 5,6 may be disposed between the correspond bearing supports 3,4, and a hardened inner race 7, which may be rigidly attached to or integral with the mandrel 1. While the drawings show a continuous race for the rotational elements 5,6 of the first and second bearing supports 3,4, a separate inner race may be provided for the rotational elements for each bearing support. The first bearing support 3 may be positioned relative to the center axis RA of the mandrel to provide minimal radially loading for the first bearing support. The second bearing support 4 may be positioned relative to the center axis RA of the mandrel to provide a selected desired level of radial loading for the second bearing support. As described below, the second bearing support 4 may be locked into place with a selected desired radial load by use of a lever actuator LA as shown in FIG. 2, or a pivot actuator PA as shown in FIG. 3. The radial loading applied to the second bearing support 4 may generate a radial load on the first bearing support 3. The radial loading of the second bearing support 4 may be opposite of the radial loading applied first bearing support 3 to the extent the first bearing support is radially loaded. As will be explained below, the second bearing support 4 is allowed to float during removal and/or replacement of the sleeve 2 associated with the corresponding plate roll PR and anilox roll AR, or removal of the roll AR,PR and/or mandrel 1 for maintenance or replacement. During sleeve or roll changeover, the radial loading of the second bearing support 4 may be released, as desired. For instance, for sleeve removal, the radial loading of the second bearing support 4 of the front bearing assembly FBA may be released, but the radially loading of second bearing support of the back bearing assembly BBA may not need to be released, in distinction to roll changeover, which will require that the radial loading of the second bearing support 4 of the front bearing assembly FBA and back bearing assembly BBA to be released. In releasing the radial loading of the second bearing support 4, the corresponding first bearing support 3 may return to a neutral loading to allow the first bearing support to be removed axially from the end of the mandrel for sleeve or roll changeover.

(14) Referring to FIG. 2, the first bearing support 3 may be mounted rigidly in the corresponding bearing block (e.g., FBB,BBB). The second bearing support 4 may be moved to its preload location to provide the selected desired level of radial loading with a lever actuator LA. The lever actuator may comprise a lever 8 arranged to apply a force to the second bearing support 4 and its corresponding rotational elements 6. A setscrew 9 may be provided to adjust the amount of force to be applied by the lever 8. A spring actuator may also be provided with or without the setscrew.

(15) Referring to FIG. 3, the first bearing support 3 may be mounted rigidly in the corresponding bearing block (e.g., FBB,BBB). The second bearing roller bearings 6 may be moved to preload location in pivoting or arcuate manner to provide the selected desired level of radial loading with a pivot actuator PA. The pivot actuator may comprise a pivot housing 10 arranged to apply a force to the second bearing support 4 and corresponding rotational elements 6 and provide the selected desired amount of radially loading. An adjustable spring actuator 11 may be provided to apply force to the pivot housing 10. A setscrew may also be provided with or without the spring actuator.

(16) Referring to FIG. 4, a control 30 is presented which may be used with the drive of the drive motor DM for at least one of the rolls AR,PR. The control 30 may be configured to develop a torque profile to compensate for torque transients that may be caused by the plate roll PR or anilox roll AR during rotation. An encoder coupled to the drive motor DM may provide rotational position information of the roll to the control 30. The control 30 may be programmed to determine the rotational position of the roll AR,PR relative to any torque transient caused by a hard line in a printing plate or other periodic disturbance. During set-up, the position of any transient may be determined and provided to the control 30. The control 30 may be programmed to apply an additive torque command to the motor control signal to increase the torque prior to the disturbance thereby minimizing the effects of any transient otherwise caused by the hard line and/or periodic disturbance, thereby minimizing print bounce.

(17) FIGS. 5 and 6 present plots that show the difference when an additive torque command is applied to the control 30 of the drive of the drive motor DM of the respective roll AR, PR. FIG. 5 shows a torque profile when the control 30 is configured to not apply an additive torque command to the motor control signal. FIG. 6 shows the torque profile when the control 30 is configured to apply an additive torque command to the motor control signal. As shown in FIG. 6, the peak to peak torque transient is reduced when the additive torque command is applied to the control 30 of the drive of the drive motor DM of the respective roll.

(18) Further embodiments can be envisioned by one of ordinary skill in the art after reading this disclosure. In other embodiments, combinations or sub-combinations of the above-disclosed invention can be advantageously made. The example arrangements of components are shown for purposes of illustration and it should be understood that combinations, additions, re-arrangements, and the like are contemplated in alternative embodiments of the present invention. Thus, various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims and that the invention is intended to cover all modifications and equivalents within the scope of the following claims.