Pivot-Shaft Turning of Step Workpieces Without Boundary Wear
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Solution Overview
Problem
The existing turning processes for workpieces like SUS and titanium alloys face issues with shortened tool life due to boundary wear and generate cutting residue when using a single point tool with a small cutting edge angle, requiring additional tools and increasing machining time, while specialized lathes with motors in the tool holder are costly and lack rigidity for rough processing.
Innovation Solution
A turning process method using a machine tool with a pivot shaft that adjusts the cutting edge angle to less than 90° for the small diameter portion and 90° or more for the large diameter portion, allowing the process to be completed with one single point tool without residue, maintaining tool rigidity and simplicity, and being applicable to rough processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a single point tool with a small cutting edge angle is used to process the small diameter portion, then boundary wear is suppressed and tool life is extended, but cutting residue is generated at the wall portion due to interference with the workpiece
Solution Approach 1:
The tool is made dynamically adjustable by enabling rotation around the pivot shaft during the machining process. The cutting edge angle is changed from a fixed small angle (for small diameter portion) to a larger angle (for wall portion) by rotating the tool, thereby eliminating cutting residue while maintaining the benefits of the small angle for boundary wear suppression
Solution Approach 2:
The cutting edge angle parameter is dynamically changed during the machining process. The tool rotates around the pivot shaft to alter the effective cutting edge angle from less than 90° when processing the small diameter portion to 90° or more when processing the wall portion, thereby resolving the contradiction between tool life and manufacturing precision
2Manufacturing precision
If a specialized lathe with a motor in the tool holder is used to rotate the single point tool, then cutting residue is eliminated, but the tool holder becomes expensive and rigidity is reduced
Solution Approach 1:
Instead of incorporating a motor into the tool holder, the invention uses the existing pivot shaft rotation capability of the machine tool. The tool holder design copies or leverages the machine tool's inherent rotational capability, avoiding the need for additional expensive components while achieving the same effect of variable cutting edge angle
Solution Approach 2:
The pivot shaft, which is part of the standard machine tool configuration, is utilized for a dual purpose: its primary function and an additional function of enabling cutting edge angle adjustment. This multi-functional use eliminates the need for specialized components, reducing device complexity and cost while maintaining the ability to eliminate cutting residue
3Manufacturing precision
If a specialized lathe with reduced rigidity is used to accommodate the motor in the tool holder, then cutting residue is eliminated, but rough processing capability is lost
Solution Approach 1:
The invention copies the essential function of the specialized lathe (variable cutting edge angle) using the standard machine tool's pivot shaft capability, thereby maintaining full tool rigidity and rough processing capability while achieving cutting residue elimination
Solution Approach 2:
The standard machine tool's pivot shaft mechanism serves the additional function of cutting edge angle adjustment without requiring any modification to the tool holder structure. The existing machine tool infrastructure is made to serve the dual purpose, preserving full rigidity and rough processing capability
Data Source
AI summary
A turning process method for processing a step-shaped workpiece includes: feeding a tool in a rotation axis direction and/or a radial direction of a workpiece while rotating the workpiece; using a tool that includes an insert with a main cutting edge having a straight portion and a machine tool having a pivot shaft of the tool in the machine side; processing a peripheral surface of the small diameter portion by turning the pivot shaft so as to have a cutting edge angle of less than 90°, the cutting edge angle having an angle between the straight portion of the main cutting edge and the rotation axis direction; and processing an end surface and a peripheral surface of the large diameter portion by turning the pivot shaft so as to have the cutting edge angle of 90° or more at a front of the large diameter portion.