Projection algorithm for generating interference-free five-axis machining paths

Abstract

The invention belongs to the field of related technologies for milling, and discloses a projection algorithm for generating interference-free five-axis machining paths. The projection algorithm includes steps of (1), discretizing the surfaces of workpieces to obtain triangle models; (2), building an AABB box for tools along projection directions; (3), screening the triangle models; (4), projecting each tool to a single triangle, to be more specific, acquiring projection equations according to constraint conditions, and concentrating calculation for tool contacts in tool coordinate systems; deriving a quartic equation with one unknown quantity according to the projection equations when rings of the tools are projected towards the edges of the triangles and projection directions are directions along tool shafts, and solving analytical solutions; deriving an eight-degree equation with one unknown quantity according to the projection equations when the projection directions are optional directions and subdividing intervals on the basis of Bezier cut-off processes to solve projection points; (5), outputting the projection points corresponding to the shortest projection distances. The projection algorithm has the advantage that the tools can be particularly projected to the triangles along the optional directions by the aid of the projection algorithm.

Description

technical field [0001] The invention belongs to the technical field related to milling, and more specifically relates to a projection algorithm for generating a five-axis machining track without interference. Background technique [0002] Computer numerical control (CNC) machining occupies an important place in the manufacturing industry. Compared with three-axis machining, five-axis machining increases the freedom of two rotation axes, which can achieve better fit between the tool and the machined surface, reduce machining time, and improve surface machining accuracy. Whether it is three-axis machining or five-axis machining, the calculation of the machining tool path is involved. At present, the commonly used tool path calculation strategies can be roughly divided into three types: (1) CL-surface strategy; (2) Contact-driven strategy; (3) Projection -based strategies such as figure 1 shown. For the CL-surface strategy, the set of tool locations (CL) when the tool is exa...

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Problems solved by technology

For the CL-surface strategy, the set of tool locations (CL) when the tool is exactly tangent to the workpiece is defined as the CL surface, and the tool path can be directly calculated from the determined CL surface, as shown in the literature "Mesh-based tool path generation for "constant scallop-height machining" discloses the intersection of the discretized triangular plate model of the driving surface and the offset surface to determine the CL trajectory. This method can detect and eliminate interference during the calculation of the CL trajectory, and is applicable to all APTs (Automatically Programmed Tools) tool three-axis machining and ball-end tool five-axis machining, but it cannot be applied to flat-bottomed knife, ring knife and general APT tool five-axis machining; in the Contact-driven strategy, the CC trajectory is first calculated, and then the tool axis is determined. Then calculate the CL trajectory, as described in the literature "Adaptiveiso-planar tool path generation for machining of free-form surfaces" and "Five-axis tool path generation based on machine-dependent potential field", the final trajectory generated by these methods may There is overcut, which leads to low machining accuracy and poor surface quality; for the Projection-based strategy, first determine the driving surface, plan the driving trajectory, and then use the projection algorithm to generate the machining trajectory

For example, the document "Fixed-axis tool positioning with built-in global interference checking for NC path generation" discloses that the tool machining trajectory is generated by using the algorithm based on the projection of the tool based on the driving trajectory to the discrete triangular piece of the curved surface. The pat...

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