CT Scanner Load Frame with Coaxial Servomotors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing load frames for CT scanners face challenges in sample mounting, alignment, and image quality, particularly for X-ray transparent materials, due to design limitations that cause out-of-plane motion and obstruct the X-ray source, reducing spatial resolution and image quality.
Innovation Solution
A load frame design featuring axisymmetric, triple coaxial servomotors with zero-backlash strain wave gears that rotate the test sample along a parallel axis, minimizing out-of-plane motion and allowing the X-ray source to be placed close to the sample, while using axisymmetric grips and a load cell to apply forces proportionally to the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polymer cylinder support structure is used to rotate the entire frame 360 degrees, then the thin polymer is relatively transparent to X-rays, but image quality becomes unacceptable for X-ray transparent materials like plastic, rubber, and soft tissue
Solution Approach 1:
The load frame is divided into separate functional components: a stationary base plate with fixed posts, and a separate rotating sample stage. This segmentation allows the support structure to remain stationary (providing structural integrity) while only the sample rotates, eliminating the need for a transparent polymer cylinder and improving image quality for transparent materials.
Solution Approach 2:
Instead of rotating the entire frame including the support structure (as in prior art), the invention inverts the approach by keeping the support structure stationary and rotating only the sample stage. This reversal eliminates X-ray interference from the support structure while maintaining rotational functionality.
2Measurement precision
If the source is placed near the specimen to maximize spatial resolution, then maximum spatial resolution is achieved, but the existing rotation stage and support structure obstruct the source placement
Solution Approach 1:
By separating the support structure from the rotation mechanism, the invention creates clear spatial zones: the stationary base plate occupies minimal space, while the rotating sample stage can be positioned optimally near the X-ray source without obstruction, enabling maximum spatial resolution.
Solution Approach 2:
The rotation functionality is extracted from the support structure and placed on a separate rotating stage. This extraction removes the obstruction caused by rotating support elements, allowing the X-ray source to be positioned close to the specimen for maximum resolution.
3Ease of operation
If Deben's tension grip design is used, then gripping capability is provided, but aligning the specimen axisymmetrically is difficult and centerline alignment through the thickness depends on the specimen's thickness dimension
Solution Approach 1:
The invention employs symmetric grips with axisymmetric geometry that match the symmetric rotation stage. This symmetry ensures that specimens are naturally aligned during mounting, eliminating the alignment difficulties associated with asymmetric grips. The symmetric design provides inherent centerline alignment regardless of specimen thickness variations.
Solution Approach 2:
The symmetric grips are designed to be universal and adaptable to various specimen types and dimensions. The axisymmetric design with matched rotation stage creates a universal alignment system that works consistently across different specimen geometries, eliminating the need for thickness-dependent alignment procedures.
4Ease of operation
If three aluminum posts are used in the support structure near the detector, then sample mounting is somewhat simplified, but the source distance remains a problem reducing spatial resolution
Solution Approach 1:
The support structure is segmented into a compact stationary base plate with integrated mounting features, eliminating the need for extended support posts near the detector. This compact design allows the sample to be positioned closer to the source while maintaining stable mounting, thereby improving spatial resolution.
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 design enhances CT scan resolution by minimizing extraneous motion, allowing higher precision and scalability, and achieving up to 100 times better resolution than prior art, while maintaining symmetry and precision, which is crucial for techniques like Digital Volume Correlation.
Implementation Method 1
strain wave gears that rotate the test sample along a parallel axis, minimizing out-of-plane motion
Implementation Method 2
a load cell, coupled to the third actuator and rotated by the third actuator, to generate an electrical signal, with a magnitude of the electrical signal being directly proportional to a force being applied to the test sample
Implementation Method 3
The first actuator rotates a first nut coupled to the second actuator and the second actuator rotates a second nut coupled to the second test sample grip
Data Source
AI summary
An apparatus comprises a base plate, a first fixed post, a second fixed post, a first actuator, a second actuator, a third actuator, a first test sample grip, and a second test sample grip. The first fixed post and the second fixed post are coupled to the base plate at one side thereof. The first actuator, coupled to the first fixed post and the second fixed post, rotates a test sample along an axis that runs parallel to and halfway between the first fixed post and the second fixed post. The second actuator, coupled to the first fixed post and the second fixed post, displaces the test sample along the axis that runs parallel to and halfway between the first fixed post and the second fixed post. The third actuator, coupled to the first fixed post and the second fixed post, rotates the test sample along the axis that runs parallel to and halfway between the first fixed post and the second fixed post.