基于Linux的往复走丝电火花线切割加工数控系统关键技术研究
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摘要
电火花线切割加工凭借其在加工高复杂度曲面、高精度工件、以及高硬质、高强度材料等加工方面得天独厚的优势,已成为航空航天、模具、电子、精密仪器制造不可或缺的加工方式。而往复走丝电火花线切割加工是我国基于本国国情自行研发并普遍应用的经济高效型电火花线切割加工方式。以较低成本,努力缩短其与单向走丝线切割加工方式在精度控制方面的距离是往复走丝线切割加工机床开发者的不懈追求。为达到这样的目的,在机床数控系统中依据电火花线切割加工的特点,实现软件控制是一种有效的途径。因此,本文对从数控代码读取到工作台驱动电机轨迹生成这一关键环节做了详细研究,依次设计了数控加工语言解释器、刀具半径补偿器、插补器。
本文以四轴联动电火花线切割加工为背景,采用RS274/NGC通用数控加工语言解释器,针对电火花线切割加工数控系统的需求进行了必要的修改;按照解析几何和分情况讨论的思路重新实现了二维C型刀补算法,并对锥度切割中,电极丝处于空间任意位置造成的加工误差进行了分析,给出了常规锥度加工应该采用的转接点过渡方法;四轴联动插补器的开发以逐点比较法和双平面插补控制法为基础,借鉴前者的“距离最短原则”提出了双平面插补控制法的“锥度改变最小原则”,参照前者的统一化算法进行了双平面插补控制法的统一化,并讨论了应该采取的终点判别原则。
在GNU/Linux操作系统上使用跨平台的Qt图形用户界面支持库实现了往复走丝线切割数控系统关键技术,通过图形仿真验证了研究成果。
Because of the outstanding performances on machining complex curved surface, high accuracy workpiece and material with high hardness and strength, Wire Electrical Discharge Machining (WEDM) has become the indispensible method of aerospace manufacture, mould cutting, electronic facility and precision instrument machining. Reciprocating feed WEDM, which consumes less time and wire electrode, is independently developed machining method originated according to China's national condition. Since the appearance of the Reciprocating feed WEDM Numerical Control (NC) machine, the developers have never stopped to purpose on shortening the distance between reciprocating feed WEDM and one-way WEDM on accuracy controlling aspect at a low cost. It is an efficient way to fulfill this task that design and implement software control algorithms on NC system according to the characteristics of WEDM. Hence, this article gave a research on the topics from NC code reading to wire electrode path generating and introduced the design method of NC code interpreter, tool radius compensator and interpolator in sequence.
The article was based on four-axis linkage WEDM, modified the RS274/NGC, a general NC code interpreter, according to WEDM NC code characteristics; re-implemented the C-type tool radius compensation in two-dimension plane using the knowledge of analytic geometry and analyzed the compensation error during taper machining; The development of four-axis linkage interpolation was the combination of ?Point by Point Comparison method (PPC)? and ?Dual-plane Interpolation Control method (DIC)?. Seeing that PPC had an improvement in the light of ?distance minimum principle? and unified programming, the article in this chapter proposed a ?tapering minimum principle' and extended the unified programming to DIC. This chapter also discussed the end discrimination method should take.
The research project realized key techniques of NC System for reciprocating feed WEDM using Qt GUI library in the GNU/Linux OS environment, tested and verified the achievements of the research by graphic simulation.
本文以四轴联动电火花线切割加工为背景,采用RS274/NGC通用数控加工语言解释器,针对电火花线切割加工数控系统的需求进行了必要的修改;按照解析几何和分情况讨论的思路重新实现了二维C型刀补算法,并对锥度切割中,电极丝处于空间任意位置造成的加工误差进行了分析,给出了常规锥度加工应该采用的转接点过渡方法;四轴联动插补器的开发以逐点比较法和双平面插补控制法为基础,借鉴前者的“距离最短原则”提出了双平面插补控制法的“锥度改变最小原则”,参照前者的统一化算法进行了双平面插补控制法的统一化,并讨论了应该采取的终点判别原则。
在GNU/Linux操作系统上使用跨平台的Qt图形用户界面支持库实现了往复走丝线切割数控系统关键技术,通过图形仿真验证了研究成果。
Because of the outstanding performances on machining complex curved surface, high accuracy workpiece and material with high hardness and strength, Wire Electrical Discharge Machining (WEDM) has become the indispensible method of aerospace manufacture, mould cutting, electronic facility and precision instrument machining. Reciprocating feed WEDM, which consumes less time and wire electrode, is independently developed machining method originated according to China's national condition. Since the appearance of the Reciprocating feed WEDM Numerical Control (NC) machine, the developers have never stopped to purpose on shortening the distance between reciprocating feed WEDM and one-way WEDM on accuracy controlling aspect at a low cost. It is an efficient way to fulfill this task that design and implement software control algorithms on NC system according to the characteristics of WEDM. Hence, this article gave a research on the topics from NC code reading to wire electrode path generating and introduced the design method of NC code interpreter, tool radius compensator and interpolator in sequence.
The article was based on four-axis linkage WEDM, modified the RS274/NGC, a general NC code interpreter, according to WEDM NC code characteristics; re-implemented the C-type tool radius compensation in two-dimension plane using the knowledge of analytic geometry and analyzed the compensation error during taper machining; The development of four-axis linkage interpolation was the combination of ?Point by Point Comparison method (PPC)? and ?Dual-plane Interpolation Control method (DIC)?. Seeing that PPC had an improvement in the light of ?distance minimum principle? and unified programming, the article in this chapter proposed a ?tapering minimum principle' and extended the unified programming to DIC. This chapter also discussed the end discrimination method should take.
The research project realized key techniques of NC System for reciprocating feed WEDM using Qt GUI library in the GNU/Linux OS environment, tested and verified the achievements of the research by graphic simulation.
引文
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