Screen Cylinder Manufacturing via Thermal Shrink Fitting
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Solution Overview
Problem
Existing screen cylinder manufacturing methods face challenges in achieving uniform screening openings and mechanical strength due to thermal stresses and burrs from welding, leading to inefficiencies and potential clogging from fiber accumulation.
Innovation Solution
The method involves heating the second rim area of support rings after assembly to reduce their diameter, clamping screen wires in notches without welding, gluing, or soldering, ensuring precise and consistent screening openings and minimizing fiber accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to fasten screen wires to support bars, then the wires are securely fixed in notches, but thermal stresses and burrs are created causing distortion and non-uniform screening openings
Solution Approach 1:
The patent removes the welding process entirely from the screen wire fastening system. Instead of welding wires to support bars, the invention uses a tensioning mechanism where wires are threaded through the support structure and tensioned to achieve secure fixation without thermal processes, thereby eliminating burrs and thermal stresses that cause distortion
Solution Approach 2:
The patent replaces the welding (thermal/mechanical bonding) system with a pure mechanical tensioning system. Wires are secured through friction and geometric constraints created by the tensioning mechanism, substituting the thermal-bonding approach with a cold-form mechanical approach that preserves dimensional accuracy
2Reliability
If welding is used to secure screen wires, then reliable fixation is achieved, but distortion of wires and changes in screening opening width occur
Solution Approach 1:
The welding process is completely extracted from the system. The patent uses a mechanical tensioning arrangement where wires pass through the support structure and are secured by friction and geometric constraints, eliminating the source of thermal distortion while maintaining reliable fixation
Solution Approach 2:
The patent changes the fundamental parameter of wire fixation from thermal-bonding (welding) to mechanical-tensioning. This parameter change transforms the fixation mechanism from a heat-affected process to a cold-form process, preserving the original wire dimensions and screening opening widths
3Ease of manufacture
If welding is used to attach screen wires, then simple and reliable fastening is achieved, but thermal stresses lead to fatigue failure under loading
Solution Approach 1:
The patent replaces the welding (thermal) system with a mechanical tensioning system. The wires are secured through friction and geometric constraints created by the tensioning mechanism, providing a cold-form solution that eliminates thermal stresses and their associated fatigue failure modes
Solution Approach 2:
The welding process is removed entirely from the manufacturing sequence. The mechanical tensioning approach simplifies the process by eliminating heat-affected zones and thermal stress cycles, resulting in wires that are more resistant to fatigue under operational loading
4Stability of the object's composition
If welding is used to secure wires in notches, then wires cannot move in the notch, but burrs catch fibers causing gradual clogging
Solution Approach 1:
The welding process is extracted from the system, eliminating the creation of burrs on wire surfaces. The mechanical tensioning method secures wires without the thermal melting and solidification process that generates burrs, thereby preventing fiber accumulation and clogging
Solution Approach 2:
The patent converts the potential harm of wire movement (which welding prevents) into a benefit by using controlled mechanical tensioning. The wires are secured through friction and geometric constraints that provide stable positioning without creating harmful burrs, transforming the fixation approach from a harmful thermal process to a beneficial cold-form process
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 approach results in a strong, uniformly manufactured screen cylinder with minimal burrs and gaps, maintaining high screening efficiency and product quality by preventing fiber accumulation and ensuring accurate slot widths.
Implementation Method 1
heating at least one of said support rings at its second rim area essentially evenly and uniformly, i.e. symmetrically in relation to a radial centreline plane CL of the support ring after the assembly of the screen cylinder such that the temperature of the first rim area remains substantially lower, whereby the second rim area is deformed
Implementation Method 2
allowing said at least one support ring to cool down to decrease its diameter, whereby the first rim area is deformed and the screen wires are clamped in said notches
Data Source
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AI summary
The present invention relates to a method of manufacturing a screen cylinder, and a screen cylinder that is particularly suitable for screening, filtering, fractionating, or sorting cellulose pulp or fiber suspensions of the pulp and paper making industry, or other similar suspensions. The present invention relates more particularly to screening or filtering devices of the type comprising a plurality of screen wires (10) positioned at a small spacing parallel to each other, the screen wires (10) being fastened into notches in the support elements (20) by means of shrink fitting the screen wires (10) into the notches by heating the second rim area (26) of the support ring (20) evenly and uniformly after the screen wires (10) have been inserted into the notches.