BLANKET TENSIONING DEVICE

A blanket tensioning device for an image transfer medium (ITM) cylinder includes two elongated blanket holders. A long dimension of each blanket holder is substantially parallel to a long dimension of the other. At least a part of at least one of the blanket holders is moveable toward or away from the other blanket holder. The device includes at least one spring that, is longitudinally arranged with respect to the long dimension and a transmission for converting a force that is exerted by the spring to a transverse force that is applied to the moveable part. When the device is installed on the cylinder with the long dimension being oriented substantially parallel to an axis of the cylinder, and when a blanket is wrapped around the cylinder with each of opposite ends of the blanket being held by each of the blanket holders substantially parallel to the cylinder axis, the applied transverse force tensions the blanket.

DETAILED DESCRIPTION

In accordance with an embodiment of the invention, a blanket tensioning device for tensioning a blanket that is wrapped around a surface of an ITM cylinder tensions the blanket so that the blanket is held taut against the cylinder surface. The blanket tensioning device includes at least two elongated blanket holders, each blanket holder configured to hold or attach to one of two opposing ends of the blanket. The blanket holders may be installed in a longitudinal groove on the cylinder surface. For example, one or both blanket holders may be in the form of, or include, an elongated bar that may be installed on the ITM cylinder such that its long axis is oriented substantially parallel to the axis of the ITM cylinder.

Longitudinal axes of the two blanket holders (axes parallel to the long dimension of each of the elongated blanket holders) are substantially parallel to one another. Thus, each end of the blanket may be held substantially parallel to the axis of ITM cylinder by one of the blanket holders. At least a part of one or both of the bars may be moveable. When a transverse force (e.g. in a direction that is perpendicular to the longitudinal axes) is applied to a moveable part that forces the moveable part of the moveable bar toward the other bar, the blanket may be tensioned.

For example, one or both of the bars may be rotatable toward and away from the other about a rotation axis that is substantially parallel to the cylinder axis. When a torque is applied to one (or both) of the bars so as to rotate the bars toward one another, the blanket may be tensioned.

One or more springs that are longitudinally oriented with respect to the elongated blanket holders to as to fit within a longitudinal (substantially parallel to the cylinder axis) groove on the surface of the ITM cylinder. For example, the springs may be positioned between the blanket holders. A transmission is provided for converting a longitudinal force (along the axis of the spring) produced by each spring to a transverse force that is substantially perpendicular to the long dimension of the groove. The transverse force may be applied to the moveable bar or bars such as to push the bars toward one another. For example, if the moveable bar is a rotatable bar, the transverse force may be applied as a torque to the rotatable blanket-holding bar (or to both bars when both are rotatable). When ends of the blanket are held by the blanket holders, the torque that is applied to the rotatable bar may tension the blanket and hold it taut against the surface of the ITM cylinder. For example, the torque may be such as to push a distal edge (an edge furthest from the axis of the ITM cylinder) of a blanket holder in the form of a rotatable bar toward the other blanket holder.

As used herein, a spring is considered to be longitudinally arranged if the long axis of the spring is oriented closer to the length (long dimension) of the groove than to a transverse dimension (plane perpendicular to the long dimension) of the groove (e.g. the spring axis being within 45 degrees of the cylinder or groove axis). In this manner, the length of the spring may be made much longer (e.g. twice as long as, or more) than the width of the groove. Typically, the width of the groove may create a strip on the surface of the ITM cylinder that cannot be utilized for printing. Therefore, it may be a design goal to make the groove width as small as possible so as to maximize the area that may be used for printing. Thus, a spring that is longitudinally arranged may be made much longer than a spring that was transversely arranged. A blanket tensioning device in accordance with an embodiment of the invention may be configured such that an orientation of a spring changes with its length (e.g. so as to effectively cooperate with other components of the blanket tensioning device).

As used herein, a spring may be understood to include any element that is capable of exerting a restoring force when stretched or compressed. For example, a spring may include a mechanical spring such as a helical or coil spring, a resilient band or rod, a gas-filled piston or spring, a hydraulic piston, or an electromagnetic actuator. A stiffness of the spring may be characterized by a linear spring constant (e.g. in accordance with Hooke's law) or similar elastic modulus or quantity. For example, tensioning of the blanket may be accomplished by compressing (or stretching) the spring. The change in length of the spring may be limited by available space. For example, were a spring to be oriented transversely in the groove, as in prior art blanket tensioning devices, the change in length would be limited to a fraction of the width of the groove (the entire working length of the spring when installed being limited to less than the width). Therefore, the spring would typically, in the case of the prior art device, be required to have a high spring constant (be very stiff) in order to provide a required tensioning force.

Orienting the spring longitudinally within the groove, in accordance with embodiments of the present invention, may enable using a spring whose length is longer than the width of the groove. For example, in some embodiments, the length of the groove may he approximately equal to ten times the width of the groove and two or four springs may be arranged longitudinally within the length of the groove. In such a case, the length of each spring could be up to one quarter of the length of the groove, or about 5 times (for two springs) or 2.5 times (for four springs) the width of the groove, with the available change in length for providing a tensioning force being similarly proportionally larger. Thus, when the spring is oriented longitudinally, the spring could have a lower spring constant than would a transversely oriented spring.

A blanket that is tensioned by the blanket tensioning device may stretch with use, in time, or in response to a mechanical stress or environmental conditions (e.g. temperature, humidity). In addition, the dimensions of blankets as manufactured may vary slightly from blanket to blanket in accordance with a manufacturer's tolerances. Since the lengths (herein referring to the dimension of the blanket that is wrapped axially about curved surface of the ITM cylinder) of the blankets may vary, tensioning of a blanket may require the spring to be compressed (or stretched) by varying amounts in order to hold the blanket taut against the surface of the ITM cylinder. Such varying amounts of compression (or stretching) of the spring may change the tensioning force that is exerted on the blanket so as to hold the blanket taut.

Use of a spring or resilient element to tension the blanket may maintain the tautness of the blanket when the length of the blanket changes without any further action on the part of an operator or a device controller. On the other hand, use (as in some prior art devices) of a non-resilient element (e.g. a screw-operated tensioning device) may require constant monitoring and active adjustment of the tensioning of the blanket.

Since a shorter spring (as in the prior art), as discussed above, would generally have a large spring constant, such a variation in compression may be expected to lead to a large change in the tensioning force. For example, a longer blanket could result in a reduction of tensioning force that could enable the blanket to loosen sufficiently such that regions of the blanket could move relative to the surface of the ITM cylinder. Excessive movement (sometimes referred to as blanket creep or crawl), or reduction of tensioning of the blanket, could adversely affect printing quality. For example, blanket crawl could affect transfer of an image from a PIP cylinder to the ITM blanket or from the ITM blanket to the printing medium. Operation of a printer may be affected by non-uniform heating (and expansion) of the ITM cylinder, or inaccurate temperature measurements (for compensation purposes), blanket abrasion, blanket buckling, or reduced blanket life.

In accordance with an embodiment of the invention, a longitudinally oriented spring may be made sufficiently long so as to enable utilization of a spring with reduced spring constant. Such a reduced spring constant may thus reduce variation in tensioning forces in response to variability or changes in blanket length. As a result, a substantially reproducible and constant tensioning force may be applied to the blanket. This force may be designed to be sufficient to inhibit or prevent blanket creep or crawl.

A transmission for converting a longitudinal force of the spring to a transverse tensioning force on the blanket may include a lever, linkage, gear, cam, rack and pinion, hydraulic transmission, or similar mechanical device for converting a force in one direction to a force in another.

A blanket tensioning device in accordance with an embodiment of the invention may include a single unit that is installable in or removable from the longitudinal gap in the cylinder surface.

FIG. 1shows a section of an ITM cylinder with a blanket tensioning device in accordance with an embodiment of the invention.

Blanket tensioning device10is positioned within gap22of ITM cylinder20. A blanket25(only one end is shown) may be wrapped around surface26of ITM cylinder20, with the ends of blanket25held and tensioned by blanket tensioning device10. For example, one end of blanket25may be held by static bar14of blanket tensioning device10and the other by dynamic bar12of blanket tensioning device10.

In accordance with another embodiment of the invention, function of static bar14may be provided by structure that is fixed to ITM cylinder20(e.g. the structure including a mechanism for attaching an end of the blanket to one side of gap22). In accordance with another embodiment of the invention, static bar14may be replaced with a second dynamic bar.

Thus, all of surface26of ITM cylinder20may be covered by blanket25with the exception of gap22. When ITM cylinder20is incorporated into an offset printing device, ink in the form of a deposited image may be transferred from an adjacent PIP cylinder to blanket25. The ink on blanket25may then be transferred to a printing medium that is held between ITM cylinder20and an adjacent impression roller. Since no ink may be transferred to or from the region of gap22, rotation of ITM cylinder20may be synchronized with rotation of the PIP cylinder and motion of the printing medium. For example, the PIP cylinder and ITM cylinder20may have similar diameters and rotate at similar rates such that a single region of the PIP cylinder always contacts gap22. Thus, the printing device may be configured such that no ink of the image is ever deposited on the region of the PIP that contacts gap22.

Each end of blanket25may be provided with a stiffened section, end bar, tab, or other feature that may be held by clamping mechanism (e.g. clamp, clip, hook, or other holding mechanism) of blanket tensioning device10.

For example, blanket tensioning device10may be manipulated (e.g. by an incorporated actuation mechanism that may be operated by application of an external force, e.g. to a screw) to apply a force to rotate dynamic bar12outward away from static bar14(thus reducing a tensioning force applied by dynamic bar12). Clamps on dynamic bar12and on static bar14may be opened (e.g. separately) to enable insertion of an end of blanket25, such as a blanket end bar, and then closed so as to clamp each end of blanket25to dynamic bar12or static bar14, respectively. The actuation mechanism may then be operated to enable force provide by springs that are longitudinally arranged along blanket tensioning device10(and gap22) to apply a torque to force dynamic bar12inward toward static bar14. Forcing dynamic bar12inward toward static bar14may thus provide a tensioning force for tensioning blanket25against surface26.

As another example, a dynamic bar may be configured to move toward or away from a second bar (e.g. a static bar or second dynamic bar). For example, the dynamic bar may be configured to move along a track (or tracks), or may be constrained by guides, so as to be moveable toward or away from the second bar. In this case, forcing the dynamic bar in a direction away from the second bar may provide a tensioning force on a blanket attached to the dynamic bar and the second bar.

The longitudinally arranged springs of blanket tensioning device10may include various numbers of springs, and various types of springs.

FIG. 2Ashows a blanket tensioning device with two springs, in accordance with an embodiment of the invention.FIG. 2Bshows the blanket tensioning device ofFIG. 2Bwithout its dynamic bar so as to show interior structures.

Blanket tensioning device10includes springs16. Although two springs16are shown, either one spring or more than two springs could be used. Although coil springs are shown, spring16may include any suitable type of linear spring or resilient element. Springs16are shown as oriented parallel to a long axis of blanket tensioning device10, and to groove22(FIG. 1) inside which blanket tensioning device10is located. Other longitudinal orientations are also possible.

Spring16of blanket tensioning device10may be configured as a compression spring. For example, spring16may include a coil spring that surrounds a shaft with an axial bore, and a plunger that is configured to move in and out of the bore. One end of the coil spring may push against an end of the shaft, and another against an opposite end of the plunger. Thus, the coil spring may be compressed by pushing the plunger further into the bore. A restoring force of the spring may then push the plunger back out of the bore. The shaft and bore may constrain spring16to maintain a linear configuration and not bend or buckle. In other examples, a linear configuration of spring16may be maintained by other constraining elements. For example, spring16may be at least partially confined within a tube.

In this manner, or in a similar manner, spring16may be compressed such that a restoring force of spring16is redirected by transmission18(components of transmission18in accordance with an embodiment of the invention are described below) to apply a force to dynamic bar12(e.g. to dynamic bar rod48that is partially enclosed within an interior bore of dynamic bar12) that causes a distal edge of dynamic bar12to rotate about dynamic bar axis46toward static bar14.

The distal edges of dynamic bar12and of static bar14include blanket clamps28aand28brespectively. Blanket clamps28bmay be opened to insert an end of a blanket and closed to hold the inserted blanket end to static bar14. Similarly, blanket clamps28bmay be opened to insert an end of a blanket and closed to hold the inserted blanket end to dynamic bar12. For example, a mechanism for opening and closing blanket clamps28aand28b,and for compressing or releasing spring16, may be activated by rotating actuation screw30. For example, the mechanism for opening and closing blanket clamps28aand28bmay be coupled (e.g. by a cam follower) to a cam that is moved by rotation of actuation screw30.

Transmission18may include a lever linkage.

FIG. 3illustrates a transmission mechanism of the blanket tensioning device shown inFIG. 2A. Spring16when compressed applies forces as indicated by double arrow40. Forces are applied by each end of spring16to connection point32aof lever linkage32. Lever linkage32may pivot about pivot point36, which may be fixed to floor13(FIG. 2AandFIG. 2B) of blanket tensioning device10. The force applied to connection point32amay cause lever linkage32to rotate about pivot point36in the direction indicated by arrow44. Rotation of lever linkage32about pivot point36may pull connection point32band pull rod34in the direction indicated by arrow42. Bar connector38at an end of pull rod34may connect pull rod34to dynamic bar12(FIG. 2A), e.g. to dynamic bar rod48(FIG. 2B) that is held within an interior bore of dynamic bar12. Thus, a force on bar connector38in the direction indicated by arrow42may pull dynamic bar12toward static bar14, thus tensioning a blanket whose ends are clamped to dynamic bar12and to static bar14.

Although as illustrated inFIG. 3, a transmission18is coupled to each end of spring16, other configurations are possible. For example, one end of a spring (e.g. coil spring or gas spring) may be fixed (e.g. to structure connected to floor13), while a transmission is provided only at the other end of the spring.

FIG. 4Ashows a transverse cross section of the blanket tensioning device shown inFIG. 2Awhen holding a blanket that is not tensioned. For example, a cam or similar mechanism that is activated by rotation of actuation screw30may apply a counter-toque to dynamic bar12via rotation of lever linkage32or pushing of pull rod34. For example, lever linkage32may include a cam follower (e.g. in the form of a wheel) so that lever linkage may rotate in response to motion of a cam that is coupled to actuation screw30. Pushing pull rod34may push bar connector38against dynamic bar rod48so as to force dynamic bar12to rotate about dynamic bar axis46away from static bar14. Concurrently, a spring of blanket tensioning device10, such as spring16(FIGS. 2A and 2B) may be compressed.

Each end of blanket25(only ends of blanket25are shown partially) is clamped to one of dynamic bar12and static bar14. For example, a blanket end bar24aat one end of blanket25may be held by blanket clamps28aof dynamic bar12. Similarly, a blanket end bar24bat another end of blanket25may be held by blanket clamps28bof static bar12. The remainder (mostly not shown) of blanket25may be wrapped around surface26of ITM cylinder26(FIG. 1). Thus, rotating dynamic bar12away from static bar14may reduce or release tensioning of blanket25.

In order to tension blanket25, dynamic bar12may be rotated about dynamic bar axis46toward static bar14.

FIG. 4Bshows the blanket tensioning device shown inFIG. 4Awhen the blanket is tensioned. For example, continued rotation of actuation screw30may move the cam (or similar component of the actuation mechanism) that forced rotation of lever linkage32or pushing of pull rod34so as to no longer provide the rotating or pushing force. When the force is no longer provided, a restoring force of compressed spring16(FIG. 3), or elastic force, may operate components of transmission18, such as lever linkage32and pull rod34, to pull on dynamic bar12. For example (as shown inFIG. 3), bar connector38at an end of pull rod34may pull on dynamic bar rod48, thus pulling on dynamic bar12. Pulling on dynamic bar12may cause dynamic bar12to rotate about dynamic bar axis toward static bar14. Thus, blanket end bar24aat one end of blanket25, and that is held by blanket clamps28aof dynamic bar12, may be pulled away from blanket end bar24bat the other end of blanket25, and which is held by blanket clamps28bof static bar14. Pulling blanket end bar24aaway from blanket end bar24bmay thus tension blanket25that is wrapped around surface26of ITM cylinder26(FIG. 1).

A blanket clamp28aor28bfor holding an end of a blanket25may be operated (e.g. opened or closed) by an actuation mechanism, e.g. a mechanism that is operated by rotation of actuation screw30.

FIG. 5Ashows a blanket clamp operating mechanism for a blanket tensioning device in accordance with an embodiment of the invention, with the blanket clamp closed. AlthoughFIG. 5Ashows an operating mechanism for a blanket clamp28aon dynamic bar12, a similar operating mechanism may operate blanket clamp28bon static bar14(FIG. 4A).

Blanket clamp28aon dynamic bar12may be opened and closed by up-and-down motion of actuation bar50. For example, actuation bar50may be moved up and down by a mechanism actuated by a cam or similar actuation mechanism. The cam may be moved, e.g. by a mechanism that is operated by rotation of actuation screw30(FIG. 2A).

For example, when actuation bar50is raised, as shown inFIG. 5A, track54of actuation bar50may push actuation wheel52of clamp rocker arm51of blanket clamp28ainward (e.g. toward the right inFIG. 5A, toward static bar14shown inFIG. 4A). Inward pushing of actuation wheel52may rotate clamp rocker arm51about dynamic bar rod48(or about a similar axis of static bar14) so as to push clamp jaws56together. Thus, a blanket end bar24aat one end of blanket25may be held firmly by blanket clamp28a.

When blanket25is to be removed and replaced, blanket clamp28amay be operated to release blanket end bar24aand to enable insertion of another blanket end bar24a.

FIG. 5Bshows the blanket clamp operating mechanism ofFIG. 5Awith the clamp opened. For example, when actuation bar50is lowered, as shown inFIG. 5B, track54of actuation bar50may push actuation wheel52of clamp rocker arm51of blanket clamp28aoutward (e.g. toward the left inFIG. 5B, away from static bar14shown inFIG. 4A). Outward pushing of actuation wheel52may rotate clamp rocker arm51about dynamic bar rod48(or about a similar axis of static bar14) so as to separate clamp jaws56. Thus, a blanket end bar24aat one end of blanket25may be removed from or inserted into blanket clamp28a.Further action by the activation mechanism may close blanket clamp28a,as shown inFIG. 5A.

A similar opening and closing mechanism may operate (open or close) blanket clamp28bon static bar14of blanket tensioning device10(FIG. 4A).

FIG. 6shows another blanket clamp operating mechanism for a blanket tensioning device in accordance with another embodiment of the invention.

Blanket clamps28aand28bmay be operated (e.g. opened and closed) by operation of activation assembly62. For example, activation assembly62may include one or more longitudinally translatable bars or nuts that may be longitudinally translated (along a long axis of blanket tensioning device10) by rotation of actuation screw30. For example, a longitudinally translatable bar may be provided with one or more cams, or may in turn move one or more other components that are provided with cams. As the cam is longitudinally translated, the cam may interact with cooperating structure (e.g. cam follower) of one or more activation devices. For example, each set of blanket clamps28aor of28bmay be opened or closed in response to a longitudinal position of the cam. Similarly, a mechanism for rotating dynamic bar12about dynamic bar axis46may be actuated in accordance with a longitudinal position of the cam.

As another example, operation of activation assembly62may operate one or more gear, lever, or linkage assemblies.

For example, each blanket clamp28aor28bmay include a clamp rocker arm61that may rotate about rocker arm pivot58. Each blanket clamp28aor28bmay also include a cam operated bar64that may be pushed against clamp rocker arm61so as to close clamp jaws56. When cam operator bar is removed from pushing against clamp rocker arm61, spring60may push clamp rocker arm61in the opposite direction. Pushing clamp rocker arm61in the opposite direction may cause clamp jaws56to open. Opening clamp jaws56may enable removal of blanket end bar24aor24bfrom blanket clamp28aor28b,respectively, or insertion of a blanket end bar24aor24binto blanket clamp28aor28b, respectively.

FIG. 7shows a blanket clamp for a blanket tensioning device in accordance with another embodiment of the invention. Although blanket clamp28ais shown inFIG. 7as incorporated into dynamic bar12of a blanket tensioning device, a similar blanket clamp may be incorporated into a static bar of a blanket tensioning device.

Spring clip66of blanket clamp28ais configured to rotate clamp rocker arm51about dynamic arm rod48(or about a similar axis of a static bar) so as to close clamp jaws56. Thus, in the absence of an externally applied force, clamp jaws56may be maintained in a closed state by spring clip66so as to grasp or clamp an end of a blanket or a blanket end bar.

When removing, inserting, or replacing a blanket, clamp jaws56may be is opened and then allowed to close. For example, clamp jaws56may be opened and closed by up-and-down motion of actuation bar50. For example, actuation bar50may be moved up and down by a mechanism actuated by a cam or similar actuation mechanism. The cam may be moved (e.g. longitudinally translated), e.g. by a mechanism that is operated by rotation of actuation screw30(FIG. 2A).

For example, when actuation bar50is raised, may push actuation wheel67upward against contoured arm68. Pushing contoured arm68may rotate clamp rocker arm51about dynamic bar rod48(or about a similar axis of a static bar) so as to open clamp jaws56. When actuation bar50is then lowered, spring clip66may close clamp jaws56and hold them closed.

In accordance with embodiments of the invention, other configurations of a blanket tensioning device are possible. For example, the blanket tensioning device may include more or fewer than two springs, and may include springs that are not coil springs. For example, an embodiment of the invention may include a blanket tensioning device with gas springs. For example, a blanket tensioning device, in accordance with an embodiment of the invention, with four gas springs may provide a greater tensioning force with a lower equivalent spring constant than a similar blanket tensioning device with fewer springs or coil springs.

FIG. 8shows a blanket tensioning device with four longitudinally arranged gas springs, in accordance with an embodiment of the invention. Blanket tensioning device70includes four gas springs72. One end of each gas spring72is connected to lever linkage32, and the other to stationary connector76, each via a pivoting connection74. Thus, gas spring72may change its orientation, e.g. when its length changes as a result of an applied force or due to rotation of lever linkage32.

A blanket tensioning device in accordance with an embodiment of the invention may be operated so as to enable replacement of a blanket.FIG. 9illustrates a process for replacing a blanket on an ITR cylinder using a blanket tensioning device in accordance with an embodiment of the invention. Blanket replacement process100may include manipulation of a configuration of the blanket tensioning device (indicated by a solid border of the corresponding block of the diagram), or actions performed by a user (indicated by a dashed border). Reference is made to components shown, e.g., inFIGS. 4A,4B, and6.

Operation of activation mechanism62, e.g. by rotation of activation screw30first in one direction, and then in a reverse direction, may cause a sequence of manipulations of blanket tensioning device10(to be understood within the context of discussion ofFIG. 9to refer also to blanket tensioning device70) so as to facilitate replacement of a blanket25. For example, one or more cams may be linearly translated, e.g. longitudinally along blanket tensioning device10, so as to actuate various cooperating structure, mechanisms, or devices.

For example, in accordance with an embodiment of the invention, rotation of activation screw30may first cause rotation of dynamic bar12about dynamic bar axis46away from static bar14so as to release tensioning of blanket25(block102). Further rotation of activation screw30may cause a first set of blanket clamps, e.g. blanket clamps28bon static bar14, to open (block104), enabling removal of a first blanket end bar, e.g. blanket end bar24b(block106). Further rotation of the activation screw30may cause the first set of blanket clamps (e.g. blanket clamp28b) to close (block108). The blanket may then be removed from the outer surface of the ITM cylinder, e.g. while rotating the ITM cylinder either automatically or manually (block110). Finally, further rotation of activation screw30may cause the second set of blanket clamps (e.g. of blanket clamps28aon dynamic bar12) to open (block112), enabling removal of the second blanket end bar, e.g. blanket end bar24a(block114). Thus, removal of blanket25from the ITM cylinder may be completed.

At this point, the actions may be reversed so as to install a new blanket25: The second blanket end bar of the new blanket, e.g. blanket end bar24a,may be inserted into the open second set of blanket clamps, e.g. blanket clamps28aon dynamic bar12(block116). Reverse rotation of the activation screw30may then cause the second set of blanket clamps (e.g. blanket clamps28a) to close (block118), thus clamping the second blanket end bar (e.g. blanket end bar24a). The new blanket25may then be wrapped around the ITM cylinder, e.g. while rotating the ITM cylinder (block120). Further reverse rotation of the activation screw30may then open the first set of blanket clamps, e.g. blanket clamps28bon static bar14(block122). The first end tab of the new blanket, e.g. blanket end bar24b,may then be inserted into the open first set of blanket clamps, e.g. blanket clamps28b(block124). Further reverse rotation of the activation screw30may then cause the first set of blanket clamps (e.g. blanket clamps28b) to close (block126), thus clamping the first end tab of the new blanket (e.g. blanket end bar24b). At this point, the new blanket25is attached to the ITM cylinder. Further reverse rotation of the activation screw30may then cause rotation of dynamic bar12about dynamic bar axis46toward static bar14, thus tensioning blanket25(block128). Thus, the replaced blanket25is held taut around the ITM cylinder.

The order of operations may be varied. For example, the order in which blanket clamps28aand28bare opened or closed may be changed, or blanket clamps28aand28bmay be opened or closed concurrently.

Activation screw30may be rotated by a motor that is incorporated in, or associated with, a printing device that includes the ITM cylinder. For example, a controller of the printing device may control a motor to rotate activation screw30in response to an operator-generated input or command, or in response to a sensed state (e.g. blanket end bar removed from, or inserted in, a blanket clamp; blanket wrapped around, or removed from, the ITM cylinder surface). Alternatively, an operator may rotate activation screw30using an appropriate manual or powered tool.

In accordance with an embodiment of the invention, operations performed for replacing a blanket25(e.g. operations represented by blocks of blanket replacement process100) may be performed by one or more electrically controlled devices, e.g. electric motors or electromagnets. The electrically controlled devices may be controlled by a controller, processor, or similar analog or digital device. For example, a controller or processor may be configured to control the electrically controlled devices in accordance with programmed instructions. The programmed instructions may be stored on a volatile or non-volatile data storage or memory device. The programmed instructions may include instructions to signal an operator, or wait for operator input.