Roll Assembly Vibration Attenuation via Flexible Bearing Housing
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Solution Overview
Problem
Fibre-web machines experience significant vibration issues, particularly with slender rolls, due to inadequate damping and stiffness, leading to disturbances in web winding processes, as traditional rigid attachments fail to effectively attenuate vibrations at resonance frequencies.
Innovation Solution
A roll assembly with a bearing housing featuring a flexible and attenuating attachment arrangement and a mass absorber, where the bearing housing vibrates at an amplitude of at least 10% of the roll centre's movement at the lowest bending eigenfrequency, enhancing the mass absorber's efficiency and providing improved damping by adjusting the spring constant and loss factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid attachment is used for bearing housings, then stability and support are improved, but vibration attenuation deteriorates
Solution Approach 1:
The patent introduces an intermediate attachment arrangement between the bearing housing and machine frame that includes elastic elements (springs or rubber isolators). This intermediary component decouples the rigid connection, allowing the bearing housing to remain stable while the elastic elements absorb and attenuate vibrations, thus resolving the contradiction between stability and vibration attenuation.
Solution Approach 2:
The patent changes the stiffness parameter of the attachment arrangement by using elastic elements with specific spring constants. This parameter change allows the system to maintain stability through proper structural support while simultaneously reducing vibration transmission by selecting appropriate damping characteristics, thus resolving the contradiction between stability and vibration attenuation.
2Object-affected harmful factors
If large mass absorber is used, then vibration damping is improved, but space utilisation and structural requirements deteriorate
Solution Approach 1:
The patent optimizes the mass ratio parameter of the absorber relative to the roll mass, achieving effective vibration damping with a relatively small absorber mass (typically 5-15% of roll mass). This parameter optimization allows sufficient damping performance while minimizing space requirements and avoiding the need for excessively large mass absorbers.
Solution Approach 2:
The patent employs a dynamic vibration absorber that is tuned to resonate at the critical frequency of the roll system. By matching the natural frequency of the absorber-mass system to the problematic vibration frequency, the absorber efficiently counteracts vibrations with minimal mass, thus resolving the contradiction between vibration damping effectiveness and space utilization.
3Strength
If bearing housing is rigidly fixed, then structural support is improved, but damping efficiency deteriorates
Solution Approach 1:
The patent introduces an intermediate attachment arrangement between the bearing housing and machine frame that includes elastic elements (springs or rubber isolators). This intermediary component decouples the rigid connection, allowing the bearing housing to remain stable while the elastic elements absorb and attenuate vibrations, thus resolving the contradiction between stability and vibration attenuation.
Solution Approach 2:
The patent changes the stiffness parameter of the attachment arrangement by using elastic elements with specific spring constants. This parameter change allows the system to maintain stability through proper structural support while simultaneously reducing vibration transmission by selecting appropriate damping characteristics, thus resolving the contradiction between stability and vibration attenuation.
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
This configuration significantly enhances vibration damping efficiency, especially for slender rolls, allowing for effective operation with a relatively small mass absorber, achieving a substantial reduction in vibration amplitude and improving the overall damping performance.
Implementation Method 1
the natural frequency of the bearing housing is at least 10% lower than the lowest bending eigenfrequency of the roll
Implementation Method 2
the harmonics of the rotational speed of a paper roll produced on drums excites the natural frequencies of the drums
Implementation Method 3
the damping of the vibration of the roll assembly is arranged by the bearing housing and the mass absorber
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a roll assembly (10) for a fibre-web machine comprising, at least at one end thereof, a bearing assembly (20) with a bearing housing, which bearing housing (18) comprises a flexible and attenuating attachment arrangement, by means of which the roll can be attached in a flexible and attenuating manner on the frame or foundation (22) of the fibre-web machine. A mass absorber (24) is arranged in conjunction with the bearing housing, whereby the damping of the vibration of the roll assembly is arranged by the cooperation of the bearing housing that is attached in a flexible and attenuating manner and the mass absorber (24) in conjunction therewith. The invention also relates to a method of attenuating the vibration of a roll of a fibre-web machine.