Twist-Free Turning via Segmented Insertion on Conventional Lathes
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Solution Overview
Problem
Existing methods for producing rotationally symmetrical surfaces on workpieces, such as grinding and turning, often result in undesirable feed marks (twist) due to the need for complex machine kinematics and high-quality, expensive tools, making them time-consuming and limited to specific machining processes.
Innovation Solution
A method where a cutting edge is repeatedly inserted into the workpiece, lifted, and repositioned with a displacement path shorter than the contour width, ensuring each contour portion is twist-free and built exclusively by insertion, allowing for the use of conventional lathes and tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional turning or grinding methods are used to produce rotationally symmetrical surfaces, then the workpiece can be machined with standard equipment, but feed marks (twist) are formed on the surface which are undesirable and affect workpiece quality
Solution Approach 1:
The cutting edge is divided into multiple independent cutting points along its length. During rotation, different segments of the cutting edge contact the workpiece at different times, creating multiple discrete contour portions that are later combined to form the complete rotationally symmetrical surface, eliminating continuous feed marks
Solution Approach 2:
The cutting edge is periodically inserted into and retracted from the workpiece during each rotation cycle. This periodic insertion creates discrete contour portions at regular intervals, and through multiple rotations with progressive positioning, the complete surface is built up without continuous contact that would generate feed marks
2Manufacturing precision
If twist-free turning methods are used with special machine kinematics and high-quality tools, then feed marks can be prevented, but the equipment complexity and tool cost increase significantly
Solution Approach 1:
A conventional lathe with standard tool positioning capabilities is used to perform the twist-free turning operation. The method leverages the existing multi-functionality of conventional lathes to create complex tool paths through programmed insertion and retraction sequences, eliminating the need for specialized machine kinematics
Solution Approach 2:
The desired rotationally symmetrical contour is copied multiple times around the workpiece during successive rotations. Each insertion creates a contour portion that is a copy of the target profile, and these copies are progressively positioned and combined to build the complete surface without requiring complex real-time kinematic control
3Manufacturing precision
If high-quality tools with precise cutting edges are used to avoid feed marks, then surface quality improves, but the cost of tools and maintenance increases
Solution Approach 1:
The cutting edge is utilized in a segmented manner where only specific portions of the cutting edge contact the workpiece during each insertion. This segmentation allows the use of conventional cutting edges rather than requiring uniformly high-quality precision tools along the entire cutting edge length
Solution Approach 2:
Conventional, less expensive cutting tools are used instead of high-precision, expensive tools. The method compensates for the lower inherent quality of conventional tools through the periodic insertion technique and multiple contour portion building, achieving twist-free surfaces with cost-effective tooling
4Productivity
If conventional turning methods are used, then the machining process is simpler, but feed marks are formed which require additional time for correction or re-machining
Solution Approach 1:
The method maintains continuous productive action by systematically building the rotationally symmetrical surface through multiple rotations and progressive positioning of contour portions. Each insertion contributes to the final surface, and the periodic pattern ensures continuous material removal and surface formation without idle periods for correction
Solution Approach 2:
The workpiece is first prepared with a preliminary contour that defines the basic rotationally symmetrical shape. The periodic insertion method then refines this preliminary contour by adding precise contour portions, eliminating the need for subsequent corrective machining operations
Data Source
AI summary
The invention relates to a method, in particular a turning method, for producing a rotationally symmetrical surface on a rotating workpiece (1), wherein a cutting edge (3) is inserted into the workpiece (1) many times. During each insertion (41), a new contour portion (11; 34), also referred to as a groove, is formed. The insertion positions lie so closely together that the resulting contour (7) generated on the workpiece (1) consists exclusively of adjacent residual contours or residual grooves (11′) which have arisen from the new contour portions or grooves (11; 34). Any interim contour portions (24) which have formed between the insertion positions during repositioning of the cutting edge (3) are removed again during the next insertion (41). The resulting rotationally symmetrical surface is twist-free. The method can be implemented using conventional lathes.