Bayonet Fastening Device for NMR Probe Heads
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Solution Overview
Problem
Current fastening systems for NMR probe heads, such as 'Standard Bore' and 'Wide Bore' systems, face challenges with mechanical play and undefined forces due to temperature changes, requiring cumbersome screw-based attachments and lacking a secure locking mechanism, which complicates assembly and maintenance, especially under the NMR magnet.
Innovation Solution
A fastening device with a disc-shaped insert part and spring elements that allows for a force-variable connection between the probe head and the holding system, ensuring a play-free assembly with a defined holding force, utilizing one-piece rigid holding elements and a bayonet-style quick-release mechanism to minimize mechanical play and prevent unintentional opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed mechanical connection is established by tightening fastening screws, then mechanical stability is improved, but adaptability to temperature-induced length changes deteriorates, causing mechanical play or axial tension
Solution Approach 1:
The fastening system transitions from a static fixed-screw connection to a dynamic bayonet-style quick-release mechanism with spring elements. The spring elements provide continuous adaptive force that automatically compensates for temperature-induced length changes, maintaining stable mechanical connection without play or excessive tension throughout temperature variations.
Solution Approach 2:
The system changes the fastening parameter from fixed screw tightness to variable spring force. The spring elements are designed with specific force characteristics that allow the connection force to adapt automatically to dimensional changes in the probe head and holding system caused by temperature variations, eliminating the need for manual adjustment.
2Ease of operation
If a quick-release fastener with gate-shaped clamping system is used, then ease of operation is improved, but mechanical play deteriorates due to undefined mounting force and relaxation after overcoming maximum force
Solution Approach 1:
The gate-shaped clamping system is replaced with a spring-element-based mechanical system. Instead of relying on operator force to overcome a gate threshold and achieve undefined mounting force, the spring elements automatically provide a precise, pre-determined mounting force that eliminates play while maintaining quick-release operation.
Solution Approach 2:
The spring elements are designed to automatically self-adjust the mounting force to the optimal value. When the bayonet mechanism is engaged, the springs automatically compress to their designed force level, ensuring consistent play-free connection without requiring the operator to control or measure the tightening force.
3Productivity
If bayonet-style quick-release mechanism is used, then productivity is improved through fast assembly, but reliability deteriorates due to lack of locking mechanism against unintentional opening
Solution Approach 1:
The locking function is merged into the bayonet engagement mechanism itself. The same rotational motion that achieves quick assembly also simultaneously engages the locking feature, combining the quick-release capability with secure locking in a single integrated action, preventing unintentional opening while maintaining fast assembly.
4Reliability
If two screws are used to attach probe head to SHIM system, then reliability is improved by eliminating play, but ease of operation deteriorates due to awkward positioning under magnet and need for special screwdriver
Solution Approach 1:
The fastening function is segmented into two independent parts: the bayonet-style quick-release mechanism for rapid attachment/detachment, and the spring elements for maintaining play-free connection. This segmentation allows the operator to achieve reliable play-free mounting through simple rotational motion rather than crawling under the magnet with screwdrivers.
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 provides a compact, cost-effective fastening system that maintains NMR measurement quality by ensuring a consistent force between the probe head and the magnet, allowing for quick and safe assembly/disassembly without mechanical play, and includes a locking mechanism to prevent unintentional detachment.
Implementation Method 1
the disk-shaped insert part is designed in such a way that, with the aid of at least one spring element, e.g. in addition to a form fit, a force-variable connection can also be established between the probe head and the holding system
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
A fastening device for an NMR probe head (1) on an NMR magnet (2) with a disc-shaped insert (3) and with a holding system (4) rigidly connected to the magnet, on which the insert can be mounted, wherein a positive locking and a force-variable connection can be established between the probe head and the holding system by means of a spring element (8), is characterized in that the probe head can be fastened to the insert by means of several one-piece rigid holding elements (6) of each fixed, unalterable length, that the spring element and the holding elements are geometrically designed such that in a first, open state there is a connection with mechanical play of 0.5 mm to 5 mm between the insert and the holding elements, wherein the spring element is relaxed, and that in a second, closed state there is a connection without mechanical play between the insert and the holding elements.the spring element is under mechanical tension. This ensures a defined holding force in the final fastening state and prevents mechanical play.