STEP-compliant CNC with T-spline enabled toolpath generation capability
STEP-compliant CNC with T-spline enabled toolpath generation capability
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DOI：
10.1007/s00170-017-0253-x
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
Gang Zhao;Yazui Liu;W. Xiao;O. Zavalnyi;Lianyu Zheng
中科院分区：
文献类型：
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作者：
Gang Zhao;Yazui Liu;W. Xiao;O. Zavalnyi;Lianyu Zheng
符合STEP标准的CNC（STEP-CNC）系统已经研究了多年，并且被认为能够承担基于G代码（ISO 6983）的传统CNC操作无法执行的各种智能功能。然而，刀具轨迹生成能力需要大量的开发和计算工作，因此逐渐成为STEP-CNC未来发展道路上的主要障碍。由于目前使用的张量积参数曲面（如NURBS）的复杂性和固有缺陷，目前STEP-CNC原型中的自由曲面加工主要依赖于CAM系统中的离线刀具轨迹生成器。本文探讨了在STEP-CNC系统中实现T样条曲线的可能性，以提高自由曲面加工的在线刀具轨迹生成能力。根据ISO 14649中定义的加工策略，提出了一套具有高鲁棒性和高效率的T样条刀位轨迹生成算法。开发了一个实用的STEP-CNC系统，该系统对基于ISO 14649标准的STEP-NC代码进行解析，采用T样条扩展，在线生成刀具轨迹，并直接驱动伺服轴。通过实例验证了该方法在STEP-NC系统中的可行性和有效性。
The STEP-compliant CNC (STEP-CNC) system has been under research for years, and has been considered to be able to undertake various intelligent functions that cannot be performed by conventional CNC operations based on G-code (ISO 6983). However, the toolpath generation capability requires great developing and computing efforts, thus has gradually become a major obstacle on the future path of STEP-CNC. Due to the complexity and inherent flaws of the currently used tensor-product parametric surface (such as NURBS), the freeform surface machining in recent STEP-CNC prototypes mostly relies on the off-line toolpath generator in a CAM system. This paper explores the possibility to implement T-spline in a STEP-CNC system, so as to enhance the on-line toolpath generation capability for machining freeform surfaces. A set of toolpath generation algorithms with high robustness and efficiency is proposed for T-spline according to the machining strategy defined in ISO 14649. A practical STEP-CNC system has been developed, which parses the ISO 14649-based STEP-NC code with the T-spline extension, generates the toolpath on-line, and drives the servo axes directly. Some examples have been tested to show the feasibility as well as the efficiency of the STEP-NC compliant T-spline direct interpolation technology for the STEP-CNC system.