Torque-Limiting Fastener With Integrated Plunger Decoupling
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Solution Overview
Problem
Existing mechanical fasteners, such as bolts and nuts, often require specialized tools for proper torque application, which can lead to over- or under-tightening, resulting in assembly failures or inadequate joining.
Innovation Solution
A fastener with an integrated torque limiter, comprising a shank, a head, and a spring-loaded plunger mechanism that decouples the head from the shank when a pre-set torque is exceeded, allowing for precise tightening without specialized tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque wrenches are used to achieve specific bolt tension, then the fastening precision is improved, but the device complexity and cost increase
Solution Approach 1:
The torque limiting mechanism is merged directly into the fastener body by integrating a plunger system within the fastener's head or shaft. This eliminates the need for external torque wrenches, as the fastener itself contains the torque control functionality through its internal plunger and detent mechanism.
Solution Approach 2:
The fastener performs its own torque limiting function through the integrated plunger mechanism that automatically disengages when the preset torque is exceeded. This self-service capability eliminates the need for separate torque-limiting tools and enables precise torque control inherent to each fastener.
2Reliability
If torque wrenches are used to control fastening torque, then the fastening reliability is improved, but the ease of operation deteriorates
Solution Approach 1:
The fastener automatically limits torque through its integrated plunger mechanism without requiring the operator to use or calibrate external torque wrenches. The plunger disengages at the preset torque value, providing reliable torque control that simplifies the operation while maintaining assembly reliability.
3Measurement precision
If external torque-limiting tools are used, then the torque control precision is improved, but the device complexity increases
Solution Approach 1:
The torque control functionality is merged into the fastener body through an integrated plunger system. This eliminates the need for separate torque-limiting tools and reduces overall system complexity while maintaining precise torque control through the preset plunger engagement mechanism.
4Manufacturing precision
If specialized torque wrenches are required, then the fastening precision is improved, but the productivity decreases
Solution Approach 1:
The fastener's integrated plunger mechanism automatically provides torque limiting without requiring specialized torque wrenches or calibration procedures. This self-service capability maintains precise fastening while eliminating tool setup and calibration time, thereby improving assembly productivity.
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 integrated torque limiter ensures that fasteners are tightened to a precise torque value, reducing the risk of assembly failures, simplifying maintenance, and eliminating the need for expensive torque-limiting tools.
Implementation Method 1
a spring-loaded plunger mounted in the plunger hole, the spring-loaded plunger including a plunger and a compression spring pressing the plunger in engagement with a detent provided on the proximal end of the shank
Implementation Method 2
a compression spring pressing the plunger in engagement with a detent
Implementation Method 3
an adjustment screw threadably engaged with a threaded portion of the plunger hole, the adjustment screw adjustable in the plunger hole to adjust a compression of the compression spring
Data Source
AI summary
An adjustable torque limiting fastener has a shank extending along an axis from a proximal end to a distal end. The fastener has a head at the proximal end of the shank. A torque limiter is integrated between the head and the shank. The torque limiter is operable to rotatably decouple the head from the shank when a torque applied to the head exceed a maximum torque. The maximum torque is set by a spring plunger integrated to the head for friction engagement with the proximal end of the shank.