Compliant Thumb Wheel Assembly for Caliper Force Control
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Solution Overview
Problem
Existing calipers face challenges in providing consistent and repeatable measurement force, especially when measuring soft objects, due to variations in force application, leading to unreliable and non-repeatable measurements.
Innovation Solution
A compliant thumb wheel assembly is introduced, featuring a compliant element that elastically couples the thumb wheel to the caliper jaw, allowing for controlled force application through elastic deformation, providing tactile feedback to the user to prevent excessive force and ensure consistent measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid thumb wheel is used to move the caliper jaw, then the structure is simple and easy to manufacture, but the measurement force varies and measurements are non-repeatable
Solution Approach 1:
The patent changes the mechanical parameter of the thumb wheel from rigid to compliant by introducing an elastomeric material. This compliance allows the thumb wheel to deform elastically under applied force, providing a consistent measuring force regardless of variations in user pressure. The elastomeric material's ability to deform and return to its original shape ensures repeatable measurements while maintaining a relatively simple overall structure.
Solution Approach 2:
The elastomeric thumb wheel acts as a cushioning element that absorbs and regulates the force applied by the user. Before the force reaches the caliper jaw, the elastomeric material softens and equalizes the pressure, preventing both excessive and insufficient force application. This beforehand cushioning effect ensures that the measurement force remains within an optimal range for repeatable measurements.
2Reliability
If force sensing features are added to measure and indicate applied force, then measurement repeatability improves, but the device becomes too complex and expensive
Solution Approach 1:
The elastomeric thumb wheel is a self-regulating component that automatically provides consistent measuring force without requiring external sensing or control systems. The material's inherent elastic properties cause it to deform to a consistent extent under varying user pressures, naturally equalizing the force applied to the workpiece. This self-service mechanism eliminates the need for complex force sensors, electronics, and indication systems while maintaining measurement repeatability.
Solution Approach 2:
The elastomeric thumb wheel replaces expensive and complex force sensing electronics with a simple, inexpensive elastomeric component. While the elastomeric material may wear over time and potentially need replacement, it provides a cost-effective solution that eliminates the need for sophisticated force measurement and control systems, making the caliper more affordable and simpler to manufacture.
3Measurement precision
If a compliant element is introduced to control measuring force, then measurement consistency improves, but the device complexity increases
Solution Approach 1:
The patent changes the physical parameter of the thumb wheel from rigid to compliant by using an elastomeric material. This single parameter change fundamentally alters how force is transmitted to the workpiece, ensuring consistent measurement force. The compliance of the elastomeric material provides a mechanical solution to force control that is simpler than adding complex control systems, achieving measurement precision through material selection rather than mechanical complexity.
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 compliant thumb wheel assembly enhances measurement force control and repeatability, reducing errors and damage to soft objects by allowing users to apply a consistent measuring force, improving measurement accuracy and user experience.
Implementation Method 1
The compliant element is configured to locate the thumb wheel in an operational arrangement for driving the caliper jaw while at the same time transmitting forces between the thumb wheel and the thumb wheel mounting portion by elastic deformation.
Implementation Method 2
When a force is applied to the thumb wheel along the measuring axis direction, the compliant element flexes such that the thumb wheel displaces along the measuring axis direction relative to the thumb wheel mounting portion and the caliper jaw, and generates a measuring force that depends on that relative displacement
Data Source
AI summary
A compliant thumb wheel assembly coupled to a caliper jaw that moves along a caliper scale member along a measuring axis direction in a caliper comprises a thumb wheel, a compliant element, and a thumb wheel mounting portion rigidly coupled to the caliper jaw. The compliant element is configured to locate the thumb wheel in an operational arrangement for driving the caliper jaw while at the same time transmitting forces between the thumb wheel and the thumb wheel mounting portion by elastic deformation. When a force is applied to the thumb wheel along the measuring axis direction, the compliant element flexes such that the thumb wheel displaces along the measuring axis direction relative to the thumb wheel mounting portion and the caliper jaw, and generates a measuring force that depends on that relative displacement and which is applied to the caliper jaw along the measuring axis direction.