Membrane Valve Diaphragm Molding for Thin-Wall Purity
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Solution Overview
Problem
Existing methods for manufacturing diaphragms for diaphragm valves, particularly those made from PTFE, are complex and unsuitable for producing thin-walled components with long flow paths, and they do not meet the requirements for high-purity processes.
Innovation Solution
A method involving the injection molding of a polymer melt, such as PFA, through a centrally located feed channel into a mold cavity, using molds that move towards each other, allowing even filling and uniform distribution of the melt, and subsequent removal of the sprue to produce a diaphragm with minimal internal stresses and cleanable surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PTFE powder is pressed and sintered to manufacture a diaphragm, then the diaphragm can be produced with high purity, but the manufacturing process becomes complex and cannot produce thin-walled components with long flow paths
Solution Approach 1:
The patent changes the material state from powder to melt, enabling injection molding of thin-walled diaphragms. By heating PTFE to its melting point and injecting the melt into the mold, the process achieves thin-walled component production with uniform wall thickness, eliminating the complexity of multiple pressing and sintering steps required by conventional methods
Solution Approach 2:
The patent replaces the mechanical pressing and sintering system with an injection molding system. The injection molding machine uses a screw to plasticize and inject the polymer melt under controlled pressure and temperature, substituting the complex mechanical pressing-sintering sequence with a single integrated injection process that produces thin-walled components more efficiently
2Ease of manufacture
If the feed channel opening is located at the edge of the mold cavity, then the molding process is simple, but internal stresses build up in the diaphragm and the flow path is unnecessarily long
Solution Approach 1:
The patent positions the feed channel opening asymmetrically at the center of the diaphragm's actuating axis rather than at the edge. This central positioning creates a symmetric radial flow pattern during injection molding, allowing the polymer melt to flow evenly in all directions toward the mold walls. This symmetry balances the cooling and solidification rates, minimizing internal stresses while shortening the effective flow path length
Solution Approach 2:
The central feed channel positioning creates equipotential flow conditions where the polymer melt flows radially outward with equal pressure distribution in all directions. This uniform pressure field during injection and cooling reduces differential shrinkage and internal stresses, while the direct central-to-edge flow path minimizes the total flow distance compared to edge-fed designs
3Productivity
If the sprue remains attached to the diaphragm after molding, then the manufacturing process is simpler, but the wet side surface is contaminated and cannot be cleaned properly
Solution Approach 1:
The patent segments the diaphragm manufacturing by producing the wet side and dry side separately in a two-cavity mold. The feed channel opens into the dry side cavity, allowing the sprue to attach only to the dry side. After molding, the diaphragms are easily separated at the parting line, and the wet side emerges with a clean surface free from sprue attachment, enabling proper cleaning and sterilization while maintaining manufacturing efficiency through simultaneous production of multiple diaphragms
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 method simplifies the manufacturing process, enables the production of thin-walled diaphragms with reduced internal stresses and cleanable surfaces, suitable for high-purity applications, and prevents material leaching into the process medium.
Implementation Method 1
The molten plastic thus flows radially and uniformly into the mold cavity in all directions, preventing internal stresses in the resulting membrane
Implementation Method 2
In its liquid state, the molten plastic therefore travels a short flow path to the outside
Data Source
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AI summary
A method for manufacturing a diaphragm (102) for a diaphragm valve is provided. The method comprises: conveying a polymer melt through at least one feed channel into a mold cavity which is bounded by a first mold and a second mold; moving the first and the second mold towards each other; removing the at least one diaphragm from the mold cavity; and separating a sprue from the at least one diaphragm removed from the mold cavity.