Multi-Blade Thread Cutting With Vibration-Limited Finish Machining
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Solution Overview
Problem
The multi-blade tool used for threading workpieces often results in low machining accuracy of the screw bottom surface due to the second cutting blade cutting a portion already cut by the first cutting blade.
Innovation Solution
A machining device and method that utilizes a multi-blade tool with a first cutting blade and a second cutting blade, where the second cutting blade is shorter than the first and positioned behind it. The device includes a feeder, vibrator, and rotator, with a controller setting the vibration amplitude to prevent the second cutting blade from contacting the screw bottom surface during finish machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-blade tool with multiple cutting blades arranged side by side is used for threading, then the productivity is improved and the cutting process is more efficient, but the machining accuracy of the screw bottom surface deteriorates because the second cutting blade cuts a portion already cut by the first cutting blade
Solution Approach 1:
The multi-blade tool is divided into functional segments: the first cutting blade (front blade) is designated for groove machining only, while the second cutting blade (rear blade) is restricted to finish machining only. This segmentation of functions prevents the rear blade from interfering with the groove portion, thereby maintaining screw bottom surface accuracy while preserving the productivity benefits of multiple blades
Solution Approach 2:
The groove machining is performed as a preliminary action by the first cutting blade before the finish machining by the second cutting blade. By completing the groove formation first and then performing the finishing operation with controlled vibration, the patent ensures that the screw bottom surface is not damaged while maintaining high threading efficiency
2Manufacturing precision
If vibration is applied during groove machining to improve surface quality, then the machining accuracy is improved, but the risk of the second cutting blade contacting the screw bottom surface increases during finish machining
Solution Approach 1:
Vibration is applied periodically and selectively: it is activated during groove machining to improve surface quality and then turned off during finish machining to prevent the rear blade from contacting the screw bottom surface. This periodic application of vibration resolves the contradiction by providing its benefits when needed and eliminating its risks when not needed
Solution Approach 2:
The vibration parameters (amplitude and frequency) are changed between different machining stages. During groove machining, vibration with specific parameters is applied to enhance surface quality. During finish machining, the vibration amplitude is reduced to zero or a minimal value to prevent excessive blade movement that could cause contact with the screw bottom surface
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 approach ensures high machining accuracy of the threaded portion by preventing the second cutting blade from contacting the screw bottom surface, even when using a multi-blade tool, thereby improving the overall quality of the threaded surface.
Implementation Method 1
a vibrator relatively and reciprocally vibrating the workpiece holder and the tool post in a radial direction of the workpiece
Data Source
AI summary
A machining device threads a workpiece by relatively rotating the workpiece and a multi-blade tool and relatively moving them along a feed direction to perform cutting processes in the radial direction of the workpiece along the same cutting path in a predetermined spiral form. A controller performs a groove machining to form a threaded portion with vibration in the radial direction of the workpiece and a finish machining to form the threaded portion by bringing the multi-blade tool into contact with the grooved portion of the workpiece. The multi-blade tool has a first cutting blade and a second cutting blade arranged side by side along the feed direction. The controller sets amplitude of a vibration waveform to a value at which a cutting edge of the second cutting blade does not come into contact with the screw bottom surface of the workpiece in the finish machining.