摘要
选区激光熔化成形技术是近年来备受关注的一种快速原型制造技术,在高致密度、高尺寸精度、高机械性能金属复杂结构零件制造领域具有广泛的应用前景。目前,国内在选区激光熔化成形技术方面的研究较国外相比还有较大差距,成形加工设备及系统控制软件的研制还不成熟,在分层图形光斑补偿处理和精细工艺参数控制方面的研究极少,限制了我国选区激光熔化成形技术的应用与发展。本文对选区激光熔化成形控制系统软件关键技术的研究具有重要的工程应用价值。
基于选区激光熔化成形系统控制软件的需求分析,本文选择了在开源几何造型软件平台Open CASCADE基础上设计出CAD/CAM功能模块的三维实体绘制模块与交互式人机界面。
实体模型的重建与分层切片图形数据组织是选区激光熔化成形软件的核心部分,是整个系统运行和功能实现的基础。本文设计了统一的CAD几何对象管理数据结构、分层切片图形数据结构以及加工工艺参数数据结构,实现了多个零件的读取、显示与视图变换、分层切片数据的合理组织以及加工工艺参数的自由设置。
针对高精密零件成形工艺要求,本文详细研究了选区激光熔化成形工艺控制的分层图形光斑补偿算法,并设计了实用的相似图形识别基础算法,实现了对由于激光光斑直径造成的加工误差的补偿,识别加工图形中的预设特征部位并设定自定义加工工艺参数。最后通过上颚牙托零件工艺试验验证表明,该新型选区激光熔化成形控制系统软件实现了预定设计的功能。
Selective Laser Melting (SLM) is a promising Rapid Prototyping(RP) technology arised in recent years, which has broad application prospects in manufacturing complex metal parts with high density, high dimensional accuracy and high mechanical perfomance.At present, there is a great technique gap technology between our country and foreign countries in many aspects of SLM, such as SLM equipment mechanism, processing control, and compensation algorithm for laser spot Thus, this paper’s research on SLM system software may wish to narrow the gap, and has important engineering value.
Based on requirements analysis of the SLM system, we selected Open CASCADE an open-source geometric modeling software platform, for the design of CAD / CAM modules and interactive man-machine interface module.
Model rendering of 3D solid parts and organization of 2D sliced pattern data are the core of SLM software, which is essential for the efficiency and accuracy of the processing control. We designed a unified geometry class object model for managing CAD data structure,sliced pattern data structure and process parameters data structure,based on which we realized multiple parts read and display, sliced pattern data organization, and local process parameters setting.
For requirements of high-precision parts manufacturing, the paper also developed laser spot compensation algorithm, and similar pattern recognition algorithm for SLM process control. Software function module of processing errors compensation form the laser spot, special graphics identify and process parameters setting were realized.Finally, to test the function of the software, we manufactured a maxillary denture parts sample, the result showed that the new SLM control software well realized the intended design function.
引文
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