Pneumatic Zone-Controlled Deflection Compensation for Paper Machine Rolls
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Solution Overview
Problem
Current deflection compensation systems in paper and cardboard machines are inefficient due to high energy consumption and require tight manufacturing tolerances, making them unsuitable for large flexible rotor systems like paper machine rolls.
Innovation Solution
A pneumatic, zone-controlled deflection compensation system using aerostatic bearings with flexible mounting and porous material seals, allowing for greater misalignment and larger tolerances, which reduces energy consumption by minimizing friction and maintaining precise control of the nipload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hydraulic systems are used for deflection compensation, then the nipload can be controlled, but energy consumption increases due to viscous losses
Solution Approach 1:
The patent replaces hydraulic systems with pneumatic systems, using compressed air instead of liquid hydraulic fluid. The pneumatic loading units utilize air pressure to compensate for roll deflection, eliminating the viscous losses associated with hydraulic oil while maintaining the ability to control nipload. This substitution directly addresses the energy loss problem by using a gas-based system that avoids viscous friction.
Solution Approach 2:
The invention changes the working fluid parameter from liquid (hydraulic oil) to gas (air). This parameter change fundamentally alters the friction characteristics, replacing viscous damping with elastic compression of gas. The pneumatic system uses compressible air to absorb and compensate for deflection, resulting in significantly lower energy losses compared to the incompressible hydraulic system.
2Loss of energy
If current aerostatic bearing technology is used, then friction is reduced, but manufacturing tolerances must be narrow and tight
Solution Approach 1:
The patent employs flexible mounting arrangements that allow dynamic adjustment and tolerance compensation. The loading units are mounted flexibly on the roll shell, enabling them to adapt to misalignments and dimensional variations. This dynamic flexibility compensates for manufacturing tolerances while maintaining the low-friction aerostatic bearing operation, resolving the contradiction between energy efficiency and manufacturing precision requirements.
Solution Approach 2:
The invention uses flexible mounting structures that resemble flexible shells, allowing the bearing assembly to deform and adapt to surface irregularities. This flexibility permits the use of larger tolerances in the bearing manufacturing while still achieving the desired low-friction operation. The flexible mounting acts as a compliant element that absorbs dimensional variations without compromising the aerostatic bearing performance.
3Reliability
If rigid sealing arrangements are used, then sealing is effective, but misalignment between bearing and opposing surface cannot be tolerated
Solution Approach 1:
The patent employs flexible sealing arrangements that can dynamically adapt to misalignments between the bearing and opposing surface. These flexible seals maintain effective sealing while accommodating positional deviations, resolving the contradiction between reliable sealing and adaptability to misalignment. The flexible nature of the seals allows them to deform and maintain contact pressure even when surfaces are not perfectly aligned.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves significant energy savings and improved efficiency by utilizing air as the working fluid, reducing power consumption and maintaining precise control of the nipload, making it suitable for large flexible rotor systems.
Implementation Method 1
Pneumatic deflection compensation with air-lubricated seals would have lower friction due to the smaller viscosity of air
Implementation Method 2
The seal may comprise a body; a restrictor; and means for distributing pressurized gas to the restrictor
Data Source
AI summary
A deflection compensated roll, comprising a shaft, a shell configured to rotate around the shaft, one or more loading units between the shaft and the shell configured to adjust a nip load profile. The loading unit comprising a pressure chamber, a seal configured to seal the pressure chamber with pressurized gas, and a flexible mounting configured to mount the seal 4 flexibly on the shaft. Also, a method for controlling a nip load with a deflection compensated roll is disclosed.