Roll or roller – With measuring – testing – or indicating means – Including signal or control means
Reexamination Certificate
1999-10-22
2001-10-09
Cuda-Rosenbaum, I (Department: 3726)
Roll or roller
With measuring, testing, or indicating means
Including signal or control means
C492S016000, C492S020000
Reexamination Certificate
active
06299571
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to controlling the shape of dynamic surfaces and in particular to a system for controlling deflection of a dynamic surface of a roll.
BACKGROUND OF THE INVENTION
In many industries, such as paper making, food processing, and textiles, or any other industry that processes a web of material, rolls are used for various types of processing functions, and in many instances, the straightness of the roll is very important. For example, in a paper making assembly, roll deflection may adversely affect the quality of the product being produced because the surface of the paper reflects the shape of the roll over which it passes. Thus, it is desirable for the rolls to be as smooth as possible and devoid of any imperfections, deflections or variations so that the paper that is formed will be smooth and uniform. In addition to resulting in the production of inferior products, roll deflection may also result in damage to the roll itself or the machinery containing the roll. Thus, various attempts have been made to control the shape of rolls so as to avoid the problems described above.
U.S. Pat. No. 5,785,636 to Bonander discloses a roll having an outer surface made of a fabricated fiber matrix for strengthening and reinforcing the roll to minimize roll deflection.
U.S. Pat. No. No. 2,908,964 discloses a controllable convex roll having a pressure fluid chamber positioned between a roll axle and the roll shell. Adjusting the pressure in the pressure fluid chamber controls deflection of the roll shell. However, the roll disclosed in the '964 patent has a number of problems associated therewith including sealing difficulties resulting in leakage of pressure fluid. In addition, the roll disclosed in the '964 patent has a relatively slow response time for changing the pressure of the pressure fluid, requiring about 30 seconds to increase the pressure and about 10 seconds to decrease the pressure. As a result, the '964 patent system is unable to rapidly respond to deflections in the roll and a considerable quantity of paper is wasted when such a roll is used in paper machines. Moreover, rolls having a convex exterior surface have a limited operating range and may obtain a uniform pressure across the exterior surface only at a given load.
U.S. Pat. No. 5,197,174 to Lehmann discloses a controlled deflection roll having a rotatable roll shell supported by a row of hydraulic support elements. The support elements are connected with fluid lines that supply hydraulic fluid to the support elements for generating a pressure force at the exterior surface of the roll. The '174 patent also discloses a control device which controls the supply of the hydraulic fluid sent to each hydraulic support element. However, the Lehmann system also has a relatively slow response time for correcting a roll deflection condition.
U.S. Pat. No. 4,301,582 to Riihinen discloses a system that removes deflections from a roll using magnetic forces. The roll has a non-rotating axle with ends having a load imposed thereat and a cylindrical shell rotatably supported by bearings on the axle. A magnetic core is formed in the axle and a plurality of pole shoes are spaced from the shell by an air gap. A plurality of electromagnetic windings, each wound on the core at one of the pole shoes, produce a magnetic compensating force field between the shell and the core for responding to deflections in the roll.
U.S. Pat. No. 4,357,743 to Hefter, et al., discloses a controlled deflection roll having a roll shell which is radially movable in at least one plane in relation to a roll support. Position feelers or sensors are arranged at the ends of the roll shell for detecting one or more deflections in the roll shell as a function of deviations from a predetermined reference or set point. The position feelers control regulators operatively associated with pressure or support elements positioned between the roll support and the roll shell so that the roll shell is maintained in the reference or set position.
U.S. Pat. No. 4,062,097 to Riinhinen discloses a roll having magnetic deflection compensation that may be used in the calender or press section of a paper machine. The roll has an inner non-rotating axle and an outer shell surrounding and rotatable with respect to the axle, the axle and the shell having a common axis. The axle includes an inner magnetic structure while the shell includes an outer magnetic structure that rotates together with the shell. These inner and outer magnetic structures cooperate to provide attraction between the shell and axle on one side of the above axis and repulsion between the shell and axle on the opposite side of the axis, thereby achieving deflection control and/or compensation.
Other techniques used to reduce the detrimental effects of roll deflections include running process machinery at slower speeds in order to avoid resonance problems, and using back-up roll systems to reduce deflections. Further techniques include floating a roll in a fluid medium or using plural bearings for each bearing journal.
Therefore, there is a need to have a deflection control system for a roll that rapidly eliminates deflections in a roll. There is also a need for a deflection control system that effectively responds to deformations of the roll caused by various sources such as induced vibrations, external loading and thermal loading. There is also a need for a deflection control system that enables deflections to be induced into the roll for any purpose necessary.
SUMMARY OF THE INVENTION
The present invention addresses the above-identified problems by providing a system and method for controlling deflection of a dynamic surface. In its broadest sense, the present invention may be used to remove undesirable deflections from a dynamic surface or to actively control the dynamic surface so as to conform the dynamic surface into a desired shape. The present invention may also be used to control vibration of a dynamic surface. In preferred embodiments, the present invention may be used to control deflection of a dynamic surface on any object that rotates including, but not limited to, a roll that engages a web, a gear, wheels and/or tires. In highly preferred embodiments, the inventive system includes at least one piezoelectric actuator in communication with a roll for applying compression and tensile forces to the roll so as to control roll deflection and/or force one or more surfaces of the roll to assume certain shapes.
As is well known to those skilled in the art, piezoelectric elements may be used to covert electrical energy into mechanical energy and vice versa. For nanopositioning, the precise motion that results when an electric field is applied to a piezoelectric material is of great value. Actuators using this effect have changed the world of precision positioning. As used herein, a piezoelectric actuator means a piezoelectric device or element, or any electronic device that operates in a similar fashion to a piezoelectric element such as an electromagnet or a magnetostatic device.
The present invention may be used for a broad range of applications whereby the system components move at various speeds. For example, the deflection control system of the present invention can be used when making a paper web moving at approximately 5000 feet/minute, when making textile materials moving at approximately 100-300 feet/minute or when making paper maker's clothing (PMC) moving at approximately 1-30 feet/minute.
In accordance with one aspect of the present invention, there is provided a system for controlling deflection of a dynamic surface, such as the exterior surface of a roll. As set forth herein, the term “dynamic surface” means any surface that may change with respect to time, regardless of whether the change occurs over 5-10 minutes or over a time period as small as one microsecond. However, as microtechnology improves and microprocessors operate at faster speeds, it is contemplated that the present invention could be used for dynamic surfaces that c
Kirchner Edward C.
White James S.
Cuda-Rosenbaum I
Lerner David Littenberg Krumholz & Mentlik LLP
Morrison Berkshire, Inc.
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