Torque Collar Conduit Fitting Stroke Limiting Remake
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Solution Overview
Problem
Conduit fittings that require pull-up by turns are not suitable for industries accustomed to assembly by torque, as variations in material properties lead to unpredictable correspondence between torque and stroke, limiting the number of reliable remakes.
Innovation Solution
Incorporating a stroke limiting feature, such as a torque collar, that allows fittings to be pulled up by both torque and turns, enabling reliable remakes with consistent torque values and minimizing stroke consumption, thereby facilitating multiple remakes without over-tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fittings are pulled up by turns without a stroke limiting feature, then assembly is simple, but stroke consumption varies unpredictably leading to unreliable remakes
Solution Approach 1:
The torque collar provides tactile feedback to the assembler when the fitting reaches its stroke limit. The collar becomes difficult to rotate when the ferrules have advanced sufficiently, giving immediate feedback that the pull-up is complete. This feedback mechanism ensures consistent stroke application across multiple remakes without requiring complex measurement tools.
Solution Approach 2:
The torque collar is designed to be manipulated directly by the assembler using finger pressure or simple tools. The enlarged flange with wrench flats allows the fitting to pull itself up to the correct stroke position through the torque applied to the collar, eliminating the need for external stroke limiting devices or complex assembly procedures.
2Reliability
If a torque collar with enlarged flange is added to provide torque control, then remake reliability improves, but device complexity increases
Solution Approach 1:
The torque collar is integrated with the fitting body through threading, merging two functional elements into a unified assembly. The collar combines stroke limiting, torque application, and visual/tactile indication functions into a single component that becomes an integral part of the fitting structure, rather than adding separate auxiliary devices.
Solution Approach 2:
The torque collar serves multiple functions simultaneously: it limits stroke, provides torque control, offers tactile feedback, and serves as a visual indicator of assembly status. The enlarged flange with wrench flats allows it to function both as a torque application point and as a stroke limit indicator, eliminating the need for multiple separate components.
3Productivity
If torque is applied without stroke limitation, then assembly is fast, but over-tightening occurs consuming excessive stroke
Solution Approach 1:
The torque collar is pre-configured with a specific thread pitch and flange position that inherently prevents over-tightening before it can occur. As the fitting approaches the correct stroke position, the collar geometry creates increasing resistance to rotation, preemptively stopping the assembler before excessive torque or stroke is applied. This preliminary anti-action protects against stroke consumption errors.
4Adaptability or versatility
If fittings are designed for pull-up by turns only, then they work well for initial assembly, but they cannot accommodate industries using torque wrenches
Solution Approach 1:
The torque collar transforms the static relationship between torque and stroke into a dynamic, self-regulating system. During assembly, the collar rotates freely allowing rapid assembly, but as the fitting approaches its stroke limit, the collar geometry creates increasing mechanical resistance. This dynamic response adapts to the assembler's input while maintaining precise stroke control, accommodating both turn-based and torque-wrench methodologies.
Data Source
AI summary
A conduit fitting of the type having first and second threaded fitting components and at least one conduit gripping device, further includes a stroke limiting member that allows the fitting to be pulled up by applying a predetermined torque. In one embodiment, the stroke limiting member may be a non-integral torque collar. Alternatively, the fitting may also be pulled up by turns or may have an integral torque collar. In still another embodiment, a stroke limiting member is provided that may be used to enable a fitting that is designed to be pulled up by turns to also be pulled up by torque. In other embodiments, the non-integral torque collar may be installed onto one of the fitting components, and then deformed so as to prevent or make it more difficult to remove the torque collar after installation onto the fitting component.