Doctor Blade Holder Tube Assembly for Blade Chatter Mitigation
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Solution Overview
Problem
Yankee doctor blade holders in the tissue industry face challenges with maintaining near uniform loading across the sheet width while avoiding maintenance issues like surface chatter marks, due to low machine direction stiffness and air entrainment reducing bulk modulus, leading to reduced dynamic stiffness and increased vibration.
Innovation Solution
A self-compensating tube assembly with a membrane enclosing a liquid of invariable bulk modulus, viscosity, and density, combined with dynamic means for enhancing dynamic stiffness and damping, and incorporating features like fiber reinforcement, compartmentalization, and squeeze film damping to mitigate blade chatter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid filled tube is used to assist the working blade to conform to a roll crown, then near uniform blade load is achieved, but machine direction stiffness is reduced leading to unwanted chatter
Solution Approach 1:
The tube assembly uses a composite structure combining a flexible tube material with embedded fiber reinforcement (such as carbon fiber or glass fiber). This composite construction provides both the flexibility needed for crown conformance and the stiffness required to prevent chatter, resolving the contradiction between load uniformity and structural stability.
Solution Approach 2:
The patent changes the physical parameters of the tube by incorporating materials with different elastic moduli and damping characteristics. The fiber reinforcement increases the tube's bending stiffness while the liquid filling maintains the self-compensating pressure distribution, allowing the system to achieve both uniform loading and adequate stiffness.
2Reliability
If the seal fails in the liquid tube, then loss of liquid occurs and air ingress is possible, but dynamic stiffness is reduced
Solution Approach 1:
The tube assembly includes redundant sealing mechanisms and pressure compensation features that prevent air ingress before it can significantly reduce stiffness. The design incorporates multiple seals and pressure equalization pathways that maintain system performance even if one seal degrades, providing a buffer against failure.
3Stability of the object's composition
If fiber reinforcement is added to the tube, then dynamic stiffness is increased, but device complexity increases
Solution Approach 1:
The patent uses a thin-walled flexible tube with embedded fiber reinforcement rather than a thick rigid structure. The fibers are integrated into the tube wall in a way that maintains flexibility while providing the necessary stiffness enhancement, avoiding complex external reinforcement structures.
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 solution effectively reduces blade chatter by introducing damping and enhancing dynamic stiffness, allowing the tube assembly to maintain stability under varying loads and frequencies, improving the reliability of Yankee coating and creping systems.
Implementation Method 1
The self-compensating tube assembly includes a tube including a membrane that encloses a liquid with a substantially invariable bulk modulus of elasticity, density and viscosity; and chatter responsive means for providing any of monitoring of blade chatter through pressure, damping of blade chatter, and minimizing blade chatter
Implementation Method 2
a tube including a membrane that encloses a liquid with a substantially invariable bulk modulus of elasticity, density and viscosity
Implementation Method 3
the tube through its material elastic modulus and strength, along with its geometry (thickness, height, width, shape), and 2) the liquid through its bulk modulus of elasticity
Data Source
AI summary
A self-compensating tube assembly is disclosed for use in a doctor blade holder. The self-compensating tube assembly includes a tube including a membrane that encloses a liquid with a substantially invariable bulk modulus of elasticity, density and viscosity; and chatter responsive for providing any of monitoring means of blade chatter through pressure, damping of blade chatter, and minimizing blade chatter.