Parallel-Axis Machine Tool for Stiff Precision Ferrule Grinding
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Solution Overview
Problem
Machine tools used for precision tasks, such as forming ferrule connectors for optical fibers, face challenges in achieving high stiffness and accuracy due to alignment errors and sub-surface damage during grinding, which leads to the need for aggressive processes that can cause optical transmission loss.
Innovation Solution
A machine tool configuration with first and second support arms, rotary drives, and a control arrangement that allows precise movement of the workpiece relative to a tool rotating about axes parallel to the drives, reducing compliance and enabling high-stiffness machining with minimal or no polishing required, using a grinding wheel with concentric grooves for different abrasive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional machine configurations with stacked linear slides are used, then ease of operation is improved, but manufacturing precision deteriorates due to alignment errors and compliance
Solution Approach 1:
The patent replaces traditional stacked linear slides with a parallel kinematic mechanism comprising two support arms mounted on parallel rotary axes. This substitution eliminates the cumulative alignment errors and compliance issues inherent in stacked linear guides while maintaining operational ease through programmable rotary motion control.
Solution Approach 2:
The invention transitions from linear motion in one dimension (stacked slides) to rotational motion in two parallel dimensions (support arms on parallel rotary axes). This dimensional change enables precise positioning through angular control while the parallel axis configuration provides inherent stiffness and eliminates alignment errors.
2Ease of manufacture
If compliant polishing pads are used for forming spherical surfaces, then ease of manufacture is improved, but manufacturing precision deteriorates due to compliance causing sub-surface damage
Solution Approach 1:
The patent replaces compliant polishing pads with a rigid grinding system mounted on the parallel kinematic mechanism. The high stiffness of the parallel axis configuration enables precise control of grinding forces and positions, eliminating sub-surface damage while maintaining ease of manufacture through a single-step grinding process that eliminates separate polishing operations.
3Productivity
If aggressive grinding processes are used to remove material, then productivity is improved, but object-generated harmful factors worsen due to sub-surface damage and crack propagation
Solution Approach 1:
The patent changes the fundamental parameters of the grinding process by using the parallel kinematic mechanism to enable extremely precise control of grinding depth, speed, and position. This allows material removal at high rates while maintaining surface integrity through controlled ductile regime grinding that prevents crack propagation.
Solution Approach 2:
The high precision positioning system of the parallel kinematic mechanism provides implicit feedback control, allowing real-time adjustment of grinding parameters to maintain optimal cutting conditions that maximize material removal while preventing sub-surface damage and crack formation.
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
This configuration enhances precision and reduces sub-surface damage, allowing for precise grinding of ferrule connectors without significant optical transmission loss, promoting a ductile grinding regime that minimizes crack propagation and increases machining accuracy.
Implementation Method 1
grinding a spherical angled face on a blank ferrule
Data Source
AI summary
A machine tool comprises first and second support arms, and a rigid structure which couples the first support arm to the second support arm. A first rotary drive is operable to rotate the first support arm and the rigid structure relative to each other about a first rotational reference axis, and a second rotary drive is operable to rotate the second support arm and the rigid structure relative to each other about a second rotational reference axis, wherein the first and second rotational reference axes are parallel and spaced apart by a fixed distance. A control arrangement is configured to control the first and second rotary drives such that a workpiece mount carried by the second support arm follows a predetermined path relative to a tool mount carried by the first support arm in a plane perpendicular to the rotational reference axes.