Variable Torque-Rate Test Joint for Rotary Tool Inertia Matching
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Solution Overview
Problem
Existing test joints for rotary tools used in threaded fasteners lack a moment of inertia matching that of real joints, leading to inaccurate performance testing, especially for impulse drive tools, and require energy sources for operation, which is inefficient and inconvenient.
Innovation Solution
A variable torque-rate test joint with a screw-threaded bolt matched in size and inertia to the simulated joint, using a torque-rate adjustment device with radially extending spring beams to simulate hard or soft joints, and incorporating mechanisms for rapid torque release without energy expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a disc brake mechanism is used to simulate torque in the test joint, then the torque can be varied to simulate hard or soft joints, but the moment of inertia becomes vastly greater than that of the real joint, leading to inaccurate testing of impulse drive tools
Solution Approach 1:
The patent extracts the brake mechanism from the rotating assembly, placing it on the stationary test rig instead. This removes the excessive moment of inertia from the rotating parts while maintaining the torque simulation capability through the brake's frictional force applied to the bolt head or nut.
Solution Approach 2:
Instead of braking the rotating shaft (which adds inertia), the invention inverts the approach by applying the brake force directly to the fastener head/nut while keeping the fastener itself free to rotate with minimal inertia. This reverses the conventional arrangement and solves the inertia problem.
2Adaptability or versatility
If a brake mechanism is incorporated into the test joint to control torque, then torque-rate can be adjusted, but the device requires energy sources for operation, reducing efficiency and portability
Solution Approach 1:
The test joint is designed to be manually operated without external energy sources. The operator manually applies torque to the fastener, and the brake mechanism is manually controlled to simulate the torque-rate characteristics, making the system self-sufficient and eliminating the need for power supplies.
Solution Approach 2:
The patent replaces electronically controlled brake systems with a purely mechanical brake arrangement that can be manually actuated. This substitution eliminates the need for electrical components, batteries, or other energy sources while maintaining torque control capability.
3Ease of operation
If the test joint uses a brake disc and pads arrangement to simulate torque, then torque can be removed after tightening, but the moment of inertia remains too high, causing tools to stall during impulse testing
Solution Approach 1:
The system is segmented into two independent parts: the lightweight rotating fastener assembly that accurately represents the real joint's inertia, and the stationary brake mechanism that provides torque simulation. This segmentation allows each part to be optimized independently - the fastener for accurate inertia matching and the brake for torque control.
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 test joint provides accurate performance testing by matching the moment of inertia of the simulated joint, reducing energy consumption and enabling efficient, manual operation, thus improving the reliability and portability of the testing process.
Implementation Method 1
a torque-rate adjustment device (6) positioned between the head (4) of the bolt and a shoulder (5) adjacent the screw threaded aperture, the torque-rate adjustment device comprising a washer portion (7) encircling the bolt beneath the bolt head, and one or more radially extending spring beams (8) extending from a reaction point (9) which is located radially outwardly of the bolt to support in cantilever the washer portion (7)
Data Source
AI summary
A variable torque-rate test point for the performance testing of rotary tools for threaded fasteners comprises a screw-threaded bolt (1) having a moment of inertia comparable to that of a bolt to be tightened using the rotary tool. The bolt (1) is tightened in the test joint against a torque-rate adjustment device (6) which can be adjusted to simulate a hard or a soft joint. The adjustment device (6) comprises a washer portion (7) beneath the bolt head (4), at least one spring beam (8) extending from a reaction point (9) radially outwardly of the bolt (1), and a pivotal bearing member (10) or other pivot at a mid portion of the beam (8). The beam (8) flexes as it extends in cantilever over the pivot point, and that flexure can be adjusted to vary the torque-rate of the test joint by varying the distance between the pivot point and the rotary axis of the bolt (1).