Annular Ring Milling for Large Aspheric Surface Machining
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Solution Overview
Problem
Current methods for machining large-diameter aspheric lenses face challenges such as excessive tool path length, tool wear, and low machining efficiency due to the need for long tool paths and high dynamic imbalance, which complicates precision and increases production time.
Innovation Solution
The method involves discretizing the aspheric surface into a series of equally spaced annular rings with different radii, using an annular grinding wheel tool with an outer diameter less than a quarter of the aspheric surface diameter, to minimize tool movement and maximize dynamic balance, allowing for sequential machining with improved precision and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional generating cutting method is used to machine large-diameter aspheric surfaces, then the tool path length becomes excessively long, but the machining efficiency remains low due to severe tool wear and frequent tool replacements
Solution Approach 1:
The patent divides the large-diameter aspheric surface into multiple small-diameter annular rings that can be machined separately. By segmenting the workpiece into manageable sections, the tool path length is dramatically reduced from machining the entire large surface in one operation to machining only small annular sections, thereby eliminating excessive tool travel and reducing tool wear.
Solution Approach 2:
The patent transforms the machining approach from a two-dimensional surface machining problem to a three-dimensional solution by using annular rings with radial positioning. The rings are arranged concentrically and machined in sequence from the center outward, adding a radial dimension to the tool path planning that significantly shortens the total tool travel distance compared to conventional scanning methods.
2Productivity
If the annular tool diameter is increased to cover larger areas, then the machining speed increases, but the dynamic balance performance deteriorates sharply
Solution Approach 1:
Instead of using one large-diameter annular tool, the patent segments the machining task into multiple small-diameter annular tools, each with optimal dynamic balance characteristics. The small tools (diameter less than 1/4 of the workpiece diameter) maintain excellent dynamic balance while covering the entire aspheric surface through sequential positioning of multiple rings.
3Manufacturing precision
If the screw pitch of the tool path is reduced to improve surface quality, then the surface roughness improves, but the total tool path length increases significantly
Solution Approach 1:
The patent segments the continuous tool path into discrete annular ring paths, where each ring is machined independently. This segmentation allows the use of larger effective step sizes between rings without compromising surface quality, because each ring is a closed contour that can be machined with optimized parameters independent of the overall surface dimensions.
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 reduces the number of rings required, minimizes residual errors, and significantly extends tool life by reducing dynamic imbalance, thereby enhancing machining efficiency and precision while maintaining high surface quality.
Implementation Method 1
The rings are sequentially machined via generating cutting by using an annular grinding wheel tool
Implementation Method 2
a convex round chamfer between the outer diameter and an inner diameter of the annular polishing disk has a radius of r0; and a thickness between the outer diameter and the inner diameter of the annular polishing disk is 2r0
Data Source
AI summary
A method and device for milling a large-diameter aspheric surface by using a splicing method and a polishing method to solve the problems of large time consumption and serious tool wear in the machining of a meter-scale large-diameter aspheric surface are disclosed. where an aspheric surface is discretized into a series of rings with different radii, and the rings are sequentially machined via generating cutting by using an annular grinding wheel tool with an outer diameter less than ¼ of a diameter of the aspheric surface; the rings are equally spaced, there are a total of N rings, and a width of any ring is jointly determined by the Nth ring, the (N−1)th ring, positioning accuracy and a generatrix equation of the aspheric surface; and the aspheric surface is enveloped by a large number of rings. A contact area between the tool and a workpiece surface is rings.