Radiation Detector Screw Hole Design for Loosening Prevention
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Solution Overview
Problem
Conventional radiation detectors with screw-based lid and box structures face issues with screw loosening due to uneven frictional forces, leading to potential safety hazards such as screw protrusion or ingestion.
Innovation Solution
The radiation detector design features a case with a second component having screw holes larger than the screw shaft but smaller than the screw head, reducing the loosening torque and preventing screw loosening, while allowing the lid to move smoothly with the body contours for improved patient comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lid is made movable with respect to the box to fit the examinee's body contours, then patient comfort is improved, but the screw may loosen due to uneven frictional forces
Solution Approach 1:
A washer is introduced as an intermediary component between the screw head and the lid surface. The washer distributes the frictional force more evenly across the lid surface, preventing localized high-stress points that cause screw loosening. This mediator allows the lid to remain movable for patient comfort while preventing the uneven friction distribution that leads to screw failure.
Solution Approach 2:
The friction coefficient distribution is modified by introducing the washer, which changes the interface characteristics between the screw assembly and the lid. This parameter change transforms the uneven friction distribution into a more uniform distribution, allowing the screw to maintain security while the lid remains movable to accommodate patient body contours.
2Reliability
If the screw head is made larger to prevent loosening, then screw security is improved, but the device complexity increases
Solution Approach 1:
The screw assembly is segmented into separate functional components: the screw shaft for fastening, the screw head for rotation control, and the washer for friction distribution. This segmentation allows each component to be optimized for its specific function without increasing overall complexity - the washer handles the friction distribution task that would otherwise require a more complex screw head design.
Solution Approach 2:
The washer serves multiple functions: it distributes frictional force evenly, prevents screw loosening, and maintains a compact profile. This multi-functionality achieves screw security without increasing device complexity, as the simple washer geometry performs multiple protective functions simultaneously.
3Reliability
If the screw is tightened more firmly to prevent loosening, then screw security is improved, but the ease of assembly and disassembly deteriorates
Solution Approach 1:
The washer provides beforehand cushioning by distributing the clamping force and frictional force before they can concentrate on localized points of the lid or screw head. This pre-distribution of forces allows the screw to be tightened sufficiently for security without creating excessive localized stress that would make assembly difficult or damage the components.
Solution Approach 2:
The washer acts as a mediator that enables easier assembly by reducing the peak forces required during tightening. By distributing the load evenly across the lid surface, the washer allows the screw to be tightened to a secure level without requiring excessive torque that would complicate the assembly process or risk component damage.
Data Source
AI summary
A radiation detector includes an image generator and a case. The image generator generates a radiograph according to received radiation. The case stores the image generator and includes a first component and a second component screwed to the first component. The second component is movable with respect to the first component in a direction along a seat surface of a screw by a screw hole of the second component being formed such that a diameter is larger than a diameter of a shaft of the screw but smaller than a diameter of a head of the screw. A loosening torque that acts, in a direction to loosen the screw, on the screw when the seat surface receives a frictional force from the second component is smaller than a loosening start torque that is the loosening torque of when the screw starts to loosen.