Thermal Contraction Assembly for Polymethylpentene Scanning Plate

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Solution Overview

Problem

The challenge lies in securing a polymethylpentene scanning surface to a carbon fibre-reinforced polymer housing while achieving an adequate seal, as existing adhesives fail to adhere effectively due to the low surface tension of polymethylpentene, leading to inadequate sealing characteristics in hermetically sealed dual-modality mammography devices.

Innovation Solution

A method involving cooling the polymethylpentene scanning plate to a temperature below -65°C to allow it to contract and fit within the housing, followed by thermal expansion to create an interference fit with the housing's edge, utilizing a peripheral groove and gasket for a hermetic seal, and incorporating complementary engagement formations for mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adhesive bonding is used to attach the polymethylpentene scanning plate to the housing body, then the scanning plate can be secured to the body, but the bond fails to provide an adequate hermetic seal due to the low surface tension of polymethylpentene

Engineering Contradiction:

Improvehermetic seal qualityVSAvoidbonding process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the temperature parameter of the polymethylpentene scanning plate, cooling it to below -65°C to induce thermal contraction. This parameter change enables the plate to be inserted into the housing body and creates a interference fit that provides both mechanical attachment and hermetic sealing without requiring adhesive bonding.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes thermal contraction (the opposite of thermal expansion) of the polymethylpentene scanning plate by cooling it to below -65°C. The plate contracts at low temperature to fit within the housing opening, then expands back to ambient temperature to create an interference fit with the gasket and engagement formations, providing both mechanical attachment and hermetic sealing.

Inventive Principle:

Principle #37Thermal expansion

2Reliability

If the scanning plate is made from polymethylpentene for excellent acoustic properties, then acoustic coupling is improved, but the material's low surface tension prevents adequate adhesive bonding

Engineering Contradiction:

Improveacoustic coupling qualityVSAvoidbond strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces the chemical bonding mechanism (adhesive) with a mechanical bonding mechanism (interference fit through thermal contraction and expansion). The cooled scanning plate is mechanically inserted into the housing body, and upon warming, the expansion creates a strong mechanical interference fit that provides both attachment strength and hermetic sealing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the housing is hermetically sealed and filled with non-conductive fluid for ultrasonic coupling, then acoustic impedance matching is improved, but the housing becomes substantially incompressible affecting X-ray imaging geometry

Engineering Contradiction:

Improveacoustic impedance matchingVSAvoidX-ray imaging geometry

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses a flexible gasket (such as rubber or elastomer) in a groove of the scanning plate to provide flexibility and compliance to the hermetic seal. This flexible element allows the housing to maintain hermetic sealing while accommodating the compressibility requirements for X-ray imaging geometry, as the gasket can deform under compression forces.

Inventive Principle:

Principle #30Flexible shells and thin films

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 provides a reliable hermetic seal without the need for adhesives, ensuring effective acoustic coupling and minimizing X-ray signal attenuation, while supporting compression loads and maintaining the structural integrity of the scanning assembly.

Implementation Method 1

cooling at least part of the scanning plate to a temperature of less than or equal to approximately -65° C. so that the perimeter of at least the lip contracts sufficiently to allow the lip to pass through the opening

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 2

allowing the scanning plate to return to ambient temperature and expand whilst so positioned in the body so that at least a portion of the side surface of the scanning plate engages the edge of the body

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10220574B2Method of assembling a housing for a scanning assembly

Publication Date: 2019.03.05 CAPERAY MEDICAL

AI summary

A composite housing and a method of assembling a composite housing for a scanning assembly. A body of the housing defines an opening of a first perimeter. A polymethylpentene scanning plate is provided which has lip with a marginally larger perimeter than the first perimeter. During assembly of the composite housing, at least a part of scanning plate is thermally contracted to allow it to be positioned within the opening such that the peripheral side surface of the scanning surface faces the edge of the body. When the scanning plate returns to ambient temperature and expands at least a portion of the side surface of the scanning plate engages the edge of the body.