数控渐进成形与激光切割集成的板材件加工轨迹生成

为实现切口板材件的五轴数控渐进成形与五轴激光切割的集成制造,提出一种基于Parasolid建模核心的五轴数控渐进成形与五轴激光切割集成的切口板材件加工轨迹生成算法及实现方法。给出了切口特征识别与提取、切口特征填补与曲面重建等算法;在研究曲线离散、曲面偏置等算法的基础上,考虑五轴数控渐进成形与五轴激光切割工艺的特点,给出了数控渐进成形刀位点、激光束半径补偿、挤压工具姿态和激光束姿态计算的方法;同时利用Parasolid建模核心和OpenGL完成了上述算法的系统实现。算法应用实例表明,依据该算法所开发的软件系统能够很好地实现上述功能,运行稳定可靠。     

基于VC和OpenGL的STL文件的分层和显示

STL文件是快速成型系统的标准文件类型,广泛应用于数控加工、逆向工程和有限元分析等.详细介绍了STL文件的读取和分层算法,并利用VC＋＋6.0平台结合OpenGL编程技术,实现了STL文件格式的读取、分层算法以及STL模型的三维显示、视角变换、缩放、平移和分层显示等功能.为进一步实现数控系统直接使用STL文件进行加工奠定了基础.     

激光板材下料利用率控制与分析

组织开展激光板材切割套裁监控活动,对激光板材切割过程进行分析,通过对激光切割机板材套裁技术进行研究,找出了影响原材料利用率的主要因素,对不同材料、不同板厚以及不同形状的零件进行了优化排版。通过采取措施,最大限度地提高了原材料利用率,达到了成本控制的目的。     

带有装配定位系统的STL模型直接生成算法研究

提出了在分割STL模型上直接添加装配定位系统的方法。分析了分割后各子零件STL文件中三角面片的特点，建立了有效的带有装配定位系统的STL模型直接生成算法，保证了完整原型的尺寸和形状精度。     

激光切割板材切口波纹和挂渣研究综述

综述激光切割表面质量内容及其影响因素和激光切割板材切口波纹和挂渣研究进展。     

基于激光切割的液压支架结构件工艺优化

在简要介绍激光切割的原理和激光切割特点的基础上,分析了传统液压支架结构件经火焰、等离子切割机切割后无法有效保证切割面质量和切割尺寸精度从而对后续加工工序所造成的一系列影响。激光切割是利用高密度的能量汇聚到微小的空间通过激光束加热工件,使金属或非金属的工件温度迅速上升,在非常短的时间内达到材料的熔点和沸点,并且依靠辅助气体的动力学作用把熔化的熔渣从切口中吹出去,从而在材料上形成切口。经激光切割的板材零件,切割外形尺寸精度高,能有效满足图纸尺寸精度要求,且切割面质量好能够满足工艺平面度、直线度的要求。激光切割后的板材零件,热变形量小、垂直度高,外形和内孔均有良好的切割质量。结合激光切割割优势和传统切割下料质量差对后续加工工序的影响,有效优化了35%左右的机械矫正和机械加工工序,降低了液压支架结构件零件、组件的加工成本,符合节能、高效的制造业生产模式,是目前最可靠、最有效的切割下料方案。同时激光切割也向着智能化、产线化的方向发展,实现了物流自动化、切割自动化、套料程序下发自动化的智能生产切割模式,完成了液压支架结构件的全自动智能切割工作。     

激光切割金属板材的建模与仿真研究进展

激光切割具有切割速度快、切缝质量好、加工效率高等优点,是材料加工领域中一种先进的热切割技术。阐述了激光切割的优势及应用,综述了激光切割金属板材建模与仿真的国内外研究进展,总结了激光切割金属板材过程中温度场、应力场和气体动力学的数值模拟方法。通过对比和分析不同建模方法,建立在材料激光切割切割过程中相关特性的数学模型,描述激光切割过程中发生的物理过程,预测金属板材的切割质量,为激光切割金属材料技术的进一步探索和研究提出可行性思路。     

基于DMC1856的五轴激光切割机控制系统研究

针对大功率、高精度、三维立体激光切割技术的控制问题,对多轴联动激光切割技术的轨迹插补和速度控制等问题进行了研究,提出了一种基于DMC1856运动控制器的五轴激光切割控制方案。激光切割主机采用了龙门倒挂式,其具有驱动激光头沿空间运动的X、Y、Z轴,以及激光头摆动的A、C轴共5个坐标轴。控制系统采用了NC嵌入PC的双CPU方式,在PC的Windows 7操作系统环境下,以.NET Framework为框架,开发了控制系统的后台管理程序、非均匀有理B样条曲线(NURBS)插补预处理算法等;NC部分以GALIL运动控制器DMC1856为核心,完成了NURBS插补的实时部分、位置控制、外围逻辑控制(PLC)等。在Matlab环境下对控制系统的NURBS插补算法与速度控制算法进行了仿真实验。研究结果表明,该控制系统适用于复杂自由空间曲面的激光切割,满足现代加工的高速、高精度要求。     

基于模糊控制的激光加工间隙控制设计分析

Z轴激光头的随动功能(焦位控制)是激光板材切割工艺的关键技术。为了满足激光板材加工适应复杂条件并具有快速性与稳定性的要求。针对Z轴随动功能,提出了基于模糊控制和前馈补偿相结合的控制方法,提高了激光切割头Z轴随动的动态响应性能与鲁棒性。以某数控激光切割随动系统为对象,进行仿真研究,并与普通PID控制器对比分析。结果表明:设计的模糊前馈控制器,响应特性优于普通PID控制器,具有更快的响应速度与更高的稳态精度,并能很好的消除扰动,为实际的系统优化设计提供了依据。     

中厚板激光切割技术应用与研究

着重就激光切割技术在碳钢中厚板加工中的应用进行研究探讨,通过对几种热切割技术的比较,分析激光切割技术对于中厚板加工的优劣势,总结在企业实际工作中,如何有效选择和均衡各种碳钢板材切割技术在企业生产中的高效运用。     

STL file generation from digitised data points based on triangulation of 3D parametric surfaces

For the current generation of rapid-prototyping models, laser scanners are currently being used more frequently due to rapid first measuring speed and high precision. Direct generation of an STL file from the digitised points has a great of advantage in that it can reduce time and error during the modelling process. A reduction in the number of point data is important while generating the STL file directly from the measured point data and maintaining precision. A new approach is developed in this paper to generate an STL file directly from point clouds by indicating a tolerance ε to maintain precision. The STL file can be generated directly from scattered points using a new algorithm that reduces and triangulates digitised point data based on triangulation of 3D parametric surfaces. Two experimental examples are presented to demonstrate the effectiveness and efficiency of the proposed algorithm.     

Re-triangulation in STL meshes for rapid prototyping and manufacture

The main objective of this research is to identify ways to simplify the STL meshes, while simultaneously maintaining the accuracy of the STL file. It demonstrates a technique to simplify large and complex STL triangular meshes and to optimise STL shape for rapid prototyping and manufacture. STL mesh re-triangulation can be separated into two processes, i.e., mesh deletion and mesh rearrangement. In the mesh deletion process, two kinds of weighted-value ratio algorithms can be chosen for determining the suitable value of STL mesh deletion. A genetic algorithm that incorporated fitness functions was used for the optimisation of the rearranged STL meshes. Two case studies of STL mesh reconstruction, which examine the effects of the algorithms, are presented. These studies show that optimisation of the shape of the STL file reduces its size, resulting in a reduction of the fabrication time and improvement of the rapid prototyping process.     

ADAPTIVE LAYERED CARTESIAN CUT CELL METHOD FOR THE UNSTRUCTURED HEXAHEDRAL GRIDS GENERATION

Adaptive layered Cartesian cut cell method is presented to solve the difficulty of the unstructured hexahedral anisotropic Cartesian grids generation from the complex CAD model. Vertex merging algorithm based on relaxed AVL tree is investigated to construct topological structure for stereo lithography (STL) files,and a topology-based self-adaptive layered slicing algorithm with special features control strategy is brought forward. With the help of convex hull,a new points-in-polygon method is employed to improve the Cartesian cut cell method. By integrating the self-adaptive layered slicing algorithm and the improved Cartesian cut cell method,the adaptive layered Cartesian cut cell method gains the volume data of the complex CAD model in STL file and generates the unstructured hexahedral anisotropic Cartesian grids.     

基于STL文件的实体分割算法研究

由于快速成型机加工尺寸的限制,难于制造尺寸较大的零件。针对这一问题本文提出一种基于STL文件格 式的实体分割算法,对STL文件分割过程中的关键问题进行了详细地论述,包括:截面轮廓的生成,截交三角面片的 处理和截面轮廓的三角化算法;通过对STL文件的分割处理,提高了快速成型系统对大尺寸零件的制造能力。     

A study on the effect of rectangular cut out on laser forming of AISI 304 plates

Laser bending of a rectangular AISI 304 plate with a rectangular cut out is investigated in the present work. In particular, effects of process parameters: laser power, scanning speed, and geometric parameters: dimensions of the cut out of sheet metal on temperature distribution and bending angle are explored with the help of numerical simulation. Analyses are carried out through a coupled thermo-mechanical formulation with finite element method using COMSOL MULTIPHYSICS. The temperature distribution and deformation of sheet metal have been obtained from numerical simulations. The bending angle is affected by process parameters, namely, laser power, scanning speed, and width of the cut out of the sheet metal. Position of the cut out vis-à-vis the scanning path and length of the cut out have very little effect on the bending angle.     

The effect of continuous and pulsed beam modes on cut path deviation in diode laser cutting of glass

During laser cleaving of brittle materials, with the controlled fracture technique, thermal stresses are generated which induce the crack and extend it along the cutting path, subsequently causing material separation. One of the problems in laser cutting of glass with this technique is the cut path deviation at the leading and the trailing edges of the glass sheet. Previous work with a continuous beam diode laser has shown the deviation to be partly due the high magnitudes of thermal stresses generated near the edges of the sheet. This paper reports on the effects of using a pulsed diode laser to cut soda lime glass. The effect of pulse parameters and cutting speed on the quality output variables such as cut deviation angle and surface finish are studied. Finite element modelling is also used to simulate the effects of the moving beam on stress generations to facilitate the understanding of the process mechanisms, and the results are compared with the experimental data. This work shows how to minimise the cut path deviation at the edges by reducing thermal stresses using optimum pulsed diode laser parameters and providing additional flexibility to the process.     

Modeling of vapor-to-melt ratio in laser cutting aluminum alloy sheet

To study the regular pattern of vapor-to-melt ratio in laser cutting sheet metal, a physical model of vapor-to-melt ratio is developed to demonstrate the material remove forms of vaporization-melt in cutting area and the state of energy and mass flow in the molten layer. Variation of vapor-to-melt ratio with laser power and cutting velocity is obtained by laser cutting of 6063 aluminum alloy sheet. The 0.5-mm sheet thickness is carried out on a JK701H Nd:YAG pulse laser cutting system by simulating under the regression correction of cut radius. Observation on the cut samples with different parameters (65 W, 85 W, 105 W varied with laser power increasing, and 2.2 mm/s, 2.0 mm/s, 1.8 mm/s with decreasing of beam cutting speed) and the calculations show that vapor-to-melt ratio increases (0.595–1.995, 0.672–2.631, 0.787–4.171) with laser power (65 W–110 W) and decreases with cutting velocity (1.8 mm/s–2.4 mm/s). At the same time, the laser cutting quality increases with vapor-to-melt ratio and the decrease with thickness of residual molten layer. The results show good agreement between vapor-to-melt ratio model and experiments. The analysis verifies that this model is feasible and it makes contribution to laser precision cutting.     

Sheet metal dieless forming and its tool path generation based on STL files

This paper introduces a new sheet metal dieless forming technology. This technology adopts the principle of “layered manufacture” in rapid prototyping technology; it can form sheet metal parts without dies. A new method of tool-path generation based on STL file for sheet metal dieless forming is proposed.     

不锈钢板的CO2激光切割工艺研究

实验用CO2激光切割厚0.8mm的1Cr18Ni9Ti不锈钢板。研究了激光功率、辅助气体类型及压力、切割速度对切割质量的影响。实验显示提高切割速度能降低切缝宽度和切口横截面的表面粗糙度;而提高激光功率和氧气压力,切缝宽度也会随之提高,切口横截面更粗糙。功率650~700W、氧气压力0.3~0.5MPa、切割速度3.5~4.5m/min时切割质量最好。另外发现功率在780~1450W,氮气压力低于0.8MPa不能得到良好的切割质量。