Stress-Free Multilayer PVC Sheet via Synchronized Roll Speeds
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Solution Overview
Problem
Existing methods for manufacturing multilayer PVC sheet materials for floor and wall panels often result in the buildup of internal stresses, leading to potential fine cracks in the material.
Innovation Solution
A method involving the synchronization of roll speeds in the finishing and roughing stands with the discharge rate of the plastic strand, combined with co-extrusion of a flexible PVC layer on top of a rigid PVC layer to form a stabilizing layer, which helps prevent warping and stress buildup during the extrusion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the plastic strand is processed through rolls at high speed to increase productivity, then productivity is improved, but internal stresses build up causing fine cracks in the material
Solution Approach 1:
The patent applies dynamics by making the roll speeds adjustable and synchronized with the discharge rate of the plastic strand. The system transitions from fixed-speed rolls to dynamically controllable rolls that can adapt their speed to match the extrusion rate, thereby processing the material at optimal speeds without building excessive internal stresses while maintaining high productivity
Solution Approach 2:
The patent changes the speed parameter of the rolls from fixed to variable, synchronizing it with the discharge rate of the plastic strand. This parameter adjustment allows the processing speed to match the material flow rate, preventing stress buildup while maintaining high productivity and material integrity
2Strength
If a single-layer rigid PVC sheet is manufactured to achieve high elastic modulus, then strength is improved, but warping occurs due to internal stresses
Solution Approach 1:
The patent applies composite materials by combining rigid PVC and flexible PVC in a multilayer structure. The rigid PVC layer provides the necessary elastic modulus and strength, while the flexible PVC layer acts as a stress-absorbing buffer that prevents warping and maintains sheet flatness, thus resolving the contradiction between strength and stability
Solution Approach 2:
The patent applies local quality by assigning different material properties to different layers of the sheet. The rigid PVC layer is positioned where structural strength is needed, while the flexible PVC layer is positioned to absorb stresses and prevent warping, giving each layer a specific local function that collectively solves the contradiction
3Productivity
If the discharge rate of the plastic strand is increased to improve productivity, then productivity is improved, but synchronization with roll speeds becomes difficult to maintain
Solution Approach 1:
The patent applies feedback by implementing a control system that monitors the discharge rate of the plastic strand and automatically adjusts the roll speeds to maintain synchronization. This feedback mechanism allows the system to handle variable discharge rates while maintaining proper speed coordination, thus improving productivity without excessively increasing device complexity
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 method effectively reduces internal stresses and warping, ensuring minimal expansion or shrinkage (max. 0.2% initially) and maintaining the sheet's stability, resulting in high elastic modulus and reduced risk of cracking.
Implementation Method 1
two or more rolls of a finishing stand, which processes the multilayer plastic strand into a sheet of defined thickness
Implementation Method 2
the speed of the rolls of the finishing stand and the rolls of the roughing stand is synchronized with the discharge rate of the plastic strand in sheet form from the extruder head, so that said plastic strand is processed without stress
Implementation Method 3
a second polymer mass comprising a flexible PVC is melted under pressure and is co-extruded on the first polymer mass, and then both are passed through the extruder head in the form of a multilayer plastic strand
Implementation Method 4
a second polymer mass comprising a flexible PVC is melted under pressure and is co-extruded on the first polymer mass... this additional second polymer mass forming a stabilizing layer for the multilayer sheet material. The stabilizing layer preferably has the same thickness as the top layer. The stabilizing layer will prevent warping of the sheet material
Implementation Method 5
a first polymer mass comprising a rigid PVC is melted under pressure and is forced through an extruder head at a specified discharge rate
Data Source
AI summary
A method for forming a multilayer plastic sheet material is disclosed, where a first polymer mass is melted under pressure and is passed through an extruder head at a specified discharge rate in the form of a plastic strand in sheet form that is provided with one or more layers so that a multilayer plastic strand is formed. This is passed to two or more rolls of a finishing stand that processes the multilayer plastic strand into a sheet. After the plastic strand in sheet form leaves the extruder head, it is first passed between a top roll and a bottom roll of a roughing stand. The speed of the rolls of the finishing stand and the rolls of the roughing stand is synchronized with the discharge rate of the plastic strand in sheet form from the extruder head, so that the plastic strand is processed without stress.