Monolithic Vacuum Lifter Seal With Non-Porous Skin
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Solution Overview
Problem
Existing seals for vacuum material lifters delaminate over time due to environmental exposure and compression loading, leading to loss of vacuum and increased maintenance costs, and are susceptible to liquid absorption and chemical contamination.
Innovation Solution
A monolithic seal with a cured extruded natural rubber closed cell thermoset elastomer core surrounded by a continuous non-porous external skin, eliminating the need for lamination and reducing liquid absorption, formed through a process of extrusion, molding, and bonding to create a homogeneous structure with improved resistance to compression set and abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laminated polyisoprene sponge rubber seals are used to achieve sufficient thickness and compression resistance, then the seal can provide adequate vacuum sealing capability, but the seal becomes susceptible to delamination and rupture under compression loading cycles
Solution Approach 1:
The invention merges multiple layers of sponge rubber into a single monolithic extrusion rather than laminating separate sheets. This eliminates the bonded interfaces that are prone to delamination while maintaining the required thickness and compression resistance through the unified cellular structure.
Solution Approach 2:
The invention uses a composite material structure with a sponge rubber core surrounded by a solid rubber skin. This composite design provides the compression resistance of sponge rubber while the solid skin layer prevents delamination and enhances durability under cyclic loading.
2Ease of manufacture
If open cell surfaces are exposed on the seal to maximize bonding surface area during lamination, then adequate bond strength can be achieved between layers, but the exposed cells become susceptible to rapid abrasion and liquid absorption
Solution Approach 1:
The invention uses a continuous solid rubber skin as a protective shell surrounding the sponge rubber core. This skin acts as a barrier that prevents liquid absorption and abrasion of the open cells while allowing the seal to maintain its compressible functionality.
Solution Approach 2:
The invention applies different material properties to different regions of the seal: the core uses open cell sponge rubber for compression and sealing, while the outer surface uses solid rubber for abrasion and liquid resistance. This local differentiation of material quality optimizes both bonding and protection functions.
3Length of stationary object
If pressure sensitive adhesives and binding layers are used to laminate sponge rubber sheets, then the required seal thickness can be achieved, but the bonded joint becomes a weak point that can delaminate under environmental exposure and compression loading
Solution Approach 1:
The invention eliminates the need for adhesives and binding layers by extruding a monolithic seal structure. The uniform cellular foam is formed in one continuous piece, removing the weak bonded interfaces that are susceptible to delamination under environmental and mechanical stress.
Solution Approach 2:
The invention extracts and removes the problematic lamination process and adhesive layers from the seal construction. By using a single-piece extrusion, the design eliminates the bonded joints that serve as failure points under compression and environmental exposure.
4Reliability
If the seal is oriented with laminated seams in the vertical direction to minimize stresses at the joint, then delamination resistance is improved, but the exposed open cells on the contact surface remain susceptible to abrasion and liquid absorption
Solution Approach 1:
The continuous solid rubber skin serves as a protective shell that eliminates the vulnerability of exposed open cells. This skin provides a durable surface that resists abrasion and prevents liquid absorption while allowing the seal to function effectively in the vertical orientation.
Solution Approach 2:
The composite structure of sponge core with solid skin allows the seal to be oriented with the strong bonded interface (replaced by monolithic structure) in the vertical direction while the solid skin protects the contact surface from abrasion and liquid exposure.
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 prevents delamination and liquid absorption, enhancing the seal's durability and resistance to environmental degradation, reducing maintenance needs and ensuring consistent vacuum performance.
Implementation Method 1
a cured extruded natural rubber closed cell thermoset elastomer core surrounded by a continuous non porous external skin
Implementation Method 2
the seal having memory effect, such that it is resistant to permanent compression set
Implementation Method 3
a continuous non porous external skin
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A seal (52) for a vacuum lifter (20) and method of manufacture wherein the seal (52) has a continuous unbroken outer fluid resistant skin (56) of elastomer which forms a boundary around a homogeneous cellular structure with no interior seams or joints.