Elastomeric Member Compression via Blowing Agent Expansion
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Solution Overview
Problem
Existing methods for forming rubber-metal composite articles with an elastomeric member in compression are inefficient, as they either require multiple steps, struggle to maintain compression, or result in inadequate durability under dynamic load conditions, due to issues like compression set and relaxation effects.
Innovation Solution
A method involving an elastomeric composition with a blowing agent, where the composition is formed into a solid member and assembled into a gap between structural members, then expanded by heating above the blowing agent's activation temperature, with gas escape limited by a barrier or platy filler to increase compression and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-vulcanization bonding is used to maintain compression, then the rubber member remains in compression, but multiple process steps are required and compression set/relaxation effects occur
Solution Approach 1:
The patent combines the vulcanization bonding process with the compression maintenance function into a single integrated step. The elastomeric member is vulcanized in place between the rigid members, creating both the bond and the compression state simultaneously, eliminating the need for separate post-vulcanization bonding steps and reducing compression set effects.
Solution Approach 2:
The elastomeric member is positioned in the compressed state before vulcanization occurs. By establishing the compression geometry beforehand and then vulcanizing in place, the member maintains its compressed dimensions after bonding, preventing relaxation effects that would occur if compression were applied after vulcanization.
2Ease of manufacture
If vulcanization bonding is used to achieve robust adhesion, then fewer process steps are required, but thermal shrinkage removes compression and puts rubber in tension
Solution Approach 1:
The patent controls the vulcanization temperature and cooling rate parameters to minimize thermal shrinkage effects. By optimizing these thermal parameters, the rubber maintains its compressed state after vulcanization rather than shrinking into tension, achieving both robust adhesion and compression maintenance.
3Reliability
If repeated tensile deformation occurs, then crack growth tendency increases, but compression stress prevents tensile deformation
Solution Approach 1:
The patent applies preliminary compressive stress to the elastomeric member before it is subjected to dynamic or vibrational loads. This pre-compression counteracts the tensile stresses that would otherwise develop during operation, preventing crack initiation and propagation, and significantly extending fatigue life.
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 effectively maintains the elastomeric member in a state of compression, enhancing its resistance to crack growth and fatigue, and improves bonding strength, leading to increased durability in dynamic applications.
Implementation Method 1
The elastomeric member is expanded by subjecting it to a temperature at or above the activation temperature. During the expansion of the elastomeric member, the escape of gas produced by the blowing agent must be limited
Implementation Method 2
the escape of gas produced by the blowing agent must be limited in order to realize an advantageous increase in the state of compression of the elastomeric member in the gap
Implementation Method 3
The elastomeric member is then expanded by subjecting it to a temperature at or above the activation temperature
Data Source
Figure 1a~3
Figure 4~5
AI summary
A method of making a composite article includes providing an elastomeric composition with a blowing agent having an activation temperature and providing at least one structural member defining a fixed gap. The composition is formed below the blowing agent's activation temperature into a solid elastomeric member approximately the thickness of or larger than the gap. The elastomeric member is assembled into the gap, which may place the elastomeric member in a state of compression in the gap. The elastomeric member is then expanded by heating it above the activation temperature. During expansion, the escape of the gas produced is limited to increase the state of compression of the elastomer in the gap by means of confining any free surfaces or by including a platy filler such as nanoclay in the composition.