초록 ▼

An apparatus and method that provides a flexible anisotropic support, which may accommodate open, closed, or re-circulating squeeze film damper in parallel, has improved internal rolling element clearances, limits maneuver and blade loss responses by limiting rotor excursion, and has a rotor centeri

An apparatus and method that provides a flexible anisotropic support, which may accommodate open, closed, or re-circulating squeeze film damper in parallel, has improved internal rolling element clearances, limits maneuver and blade loss responses by limiting rotor excursion, and has a rotor centering feature. This is accomplished through the combination of beam and ring arrangement, which provides support anisotropy that produces beneficial cross-coupling stiffness for the support to control synchronous and non-synchronous vibration.

대표청구항 ▼

An apparatus and method that provides a flexible anisotropic support, which may accommodate open, closed, or re-circulating squeeze film damper in parallel, has improved internal rolling element clearances, limits maneuver and blade loss responses by limiting rotor excursion, and has a rotor centeri

An apparatus and method that provides a flexible anisotropic support, which may accommodate open, closed, or re-circulating squeeze film damper in parallel, has improved internal rolling element clearances, limits maneuver and blade loss responses by limiting rotor excursion, and has a rotor centering feature. This is accomplished through the combination of beam and ring arrangement, which provides support anisotropy that produces beneficial cross-coupling stiffness for the support to control synchronous and non-synchronous vibration. t of the valve members. 10. An assembly according to claim 1 further including a printed material stripping means which is positioned within the drum and actuatable to be urged into contact with a drum wall thereby moving all contacted valve members from the open position to the closed position. 11. An assembly according to claim 10 wherein the printed material stripping means is mounted at a station where the leading edge of the printed material is required to be stripped. 12. A printing machine including a vacuum drum assembly as claimed in claim 1. 13. A machine as claimed in claim 12 further including, for the drum, means for holding or directing the material against or towards the drum at the position in which the material is fed onto the drum. 14. A duplex printing machine comprising: first and second vacuum drum assemblies each as claimed in claim 1 and with the drums parallel; means for reducing an air pressure inside the drums; means for feeding material to be printed onto the first drum so that the material can be held on the first drum by vacuum and rotated therewith; first printing means for printing on the material on the first drum; means for releasing the material from the first drum in a direction towards the second drum so that the material can be held on the second drum by vacuum and rotated therewith; second printing means for printing on the material on the second drum; and means for releasing the material from the second drum. 15. A machine as claimed in claim 14 further including, for each drum, means for holding or directing the material against or towards the respective drum at the position in which the material is fed onto the respective drum. 16. A machine as claimed in claim 14 wherein, the direction in which the material is released from the first drum towards the second drum is generally parallel to and opposite to the direction in which the material is fed onto the first drum, and the direction in which the material is released from the second drum is generally parallel to and opposite to the direction in which the material is fed onto the second drum. 17. A vacuum drum assembly for a printing machine, the assembly comprising: a drum having a length and a periphery with an array of passageways distributed along its length and around its periphery to permit air to flow from outside the drum to inside the drum in response to reduced air pressure inside the drum, wherein the passageways extend through the periphery of the drum and terminate inside the drum; and an array of valve members arranged locally to said passageways, each valve member being movable between a closed position in which that valve member restricts at least one of the passageways and an open position in which the restriction of the at least one passageway is reduced, wherein the assembly is arranged such that, when a partial area of the drum is covered with material to be printed, at least some of the valve members for the passageways adjacent an edge of said partial area are open, and the valve members for the passageways which are not covered by the material and are not adjacent an edge of said partial area are closed. 18. An assembly as claimed in claim 17 wherein at least one valve member is normally closed and is opened by a pressure difference. 19. An assembly as claimed in claim 17 wherein at least one valve member is opened by a pressure difference between adjacent passageways. 20. An assembly as claimed in claim 17 wherein each passageway (40) is provided with a respective one of said valve members (48). 21. An assembly as claimed in claim 17 wherein each of the valve members affects an adjacent pair of the passageways. 22. An assembly as claimed in claim 17 further comprising: wall portions between adjacent pairs of the passageways; and each valve member comprising a butterfly valve pivotally mounted on a respective one of the wall portions and biased towards its closed position. 23. An assem