金属薄板激光弯曲成形的工艺参数研究

以不锈钢薄板的激光弯曲成形为研究对象,研究其成形的工艺过程及影响因素;介绍实验设备和激光调焦方法。通过实验研究了激光能量因素、扫描速度因素、激光光斑大小和扫描次数等因素对弯曲成形角度的影响。     

管材激光弯曲成形的试验研究

进行了管材激光弯曲的试验研究,确定了工艺参数范围及扫描方式。通过单因素试验法研究了不同的激光参数(激光功率、扫描速度、离焦量和扫描包角)、扫描次数和管径对弯曲角度的影响规律,从而得到了单因素条件下的最佳工艺参数,为激光弯曲成形零件提供了应用基础。     

板料激光弯曲成形技术的研究现状及展望

综述了近年来国内外对激光弯曲成形技术的研究现状,概述了激光工艺参数、板料几何参数及材料性能等因素对弯曲成形的影响,分析了扫描轨迹对成形结果的影响以及激光成形闭环控制系统的应用,并对板料激光弯曲成形的应用和发展前景作了展望。     

板料激光弯曲成形技术的研究现状及展望

综述了近年来国内外对激光弯曲成形技术的研究现状，概述了激光工艺参数、板料几何参数及材料性能等因素对弯曲成形的影响，分析了扫描轨迹对成形结果的影响以及激光成形闭环控制系统的应用，并对板料激光弯曲成形的应用和发展前景作了展望。     

约束对板材激光直线扫描成形的影响

板材激光弯曲成形是利用激光成形工件的柔性成形技术。以板材激光单次扫描成形过程为研究对象,对板材激光直线扫描成形过程进行了有限元模拟,分析了有约束和无约束情况下板材的变形行为。     

不锈钢钢板热应力成形试验研究及其工艺参数评价

以不锈钢钢板为研究对象,通过改变激光光束能量、光斑直径、机床扫描速度、扫描次数以及扫描路径对不锈钢钢板进行弯曲试验,研究了厚度一定的不锈钢钢板弯曲成形时的工艺参数对弯曲角度的影响,并对热应力弯曲成形的工艺参数进行评估。     

铝合金交叉筋壁板激光多道扫描成形研究

本文利用激光诱导热成形技术对5A06铝合金交叉筋壁板进行圆柱面弯曲成型的过程中,根据交叉筋分布位置,对边缘区、筋部及网格区扫描时壁板的多道扫描变形进行实验研究,讨论扫描方式对壁板成形的影响。针对多道扫描过程中非期望变形的累积效应,提出一种扫描纵向加强筋的方法来减小自由端的纵向弯曲程度,并对交叉筋壁板圆柱面弯曲成型的多道扫描流程和扫描策略进行规划,通过成形试验检验策略的有效性。     

金属层合板激光圆弧扫描弯曲成形试验研究

采用激光圆弧扫描弯曲策略,针对矩形层合板主要分析激光功率P、离焦量H、激光扫描速度v以及层合板厚度h对层合板弯曲角度及曲面变形量的变化规律及其影响作用。研究结果表明:激光功率P增大,层合板弯曲角度及曲面变形量随之增大;离焦量H、激光扫描速度v以及层合板厚度h增大,层合板弯曲角度及曲面变形量随之减小;通过激光圆弧扫描弯曲,层合板呈显著三维曲面特征,激光圆弧扫描弯曲成形时层合板长度方向中线处弯曲角度小于层合板两侧边线弯曲角度,且激光扫描线处曲面变形量最大。基于矩形层合板曲面变形特征,为实现圆顶形激光弯曲三维曲面成形,最终利用圆形层合板,采用激光径向+轴向扫描策略弯曲成形圆顶形结构,其最外侧圆周测量线z向最大位移增量达到2. 23 mm。     

板料激光曲线弯曲成形温度场的数值研究

板料激光弯曲成形是一种利用激光成形构件的柔性成形技术。以矩形板激光单次扫描成形的过程为研究对象，通过对有限元分析软件ANSYS进行二次开发，建立了基于扫描路径的动热源模型，并系统研究了各技术参数下激光弯曲温度场的动态变化。分析发现：（1）曲线扫描准稳态过程的温度峰值要小于同工况下直线扫描情况，且持续时间短暂，温度峰值不断跳跃；（2）相同工艺参数下，随着扫描路径曲率的增大，温度峰值及加热区温度梯度均减小，当扫描路径曲率继续增大时，温度峰值及加热区温度梯度却随之增大；（3）提高激光功率，降低扫描速度以及在恒定线能量密度下增大扫描速度，均使板料温度梯度增大，而增大光斑直径，温度梯度减小。     

厚钢板激光多次扫描弯曲成形的研究

采用数值模拟和实验研究分析了厚钢板激光多次扫描弯曲成形过程中弯曲角度与激光扫描次数之间的关系。建立三维热力耦合有限元模型计算了成形过程的温度场、应力场和弯曲角度的变化,对不同厚度钢板的激光多次扫描弯曲成形过程进行了实验研究,模拟结果与实验结果符合较好。在相同的工艺参数条件下,钢板越厚,弯曲角度越小。钢板弯曲角度随激光扫描次数的增加而增大,但对不同厚度钢板,它们的变化规律不同。钢板下表面的应变强化是多次扫描过程中随扫描次数增加而弯曲角度增量减小的主要原因。     

激光板料成形技术的研究及应用

金属板料激光成形技术是近年来出现的一种先进柔性加工技术.分别介绍了激光热应力成形、激光冲击成形(LSF)和激光喷丸成形(LPF)的成形机理,分析了成形的主要影响因素.影响这三种激光成形方式的因素主要有:激光参数、扫描轨迹、材料性质、板料几何参数和约束边界条件等.分别从机理、工艺参数、成形工艺等方面分析了这三种板料激光成形的技术特点.最后,对这三种激光板料成形技术的应用前景进行了展望,并指出激光板料成形技术在成形的精确控制及成形复杂件方面存在的一些尚待解决的关键问题.     

先进激光制造技术研究新进展

介绍了激光板与管无模成形、激光表面强化处理、激光微细加工和激光直接沉积成形等四种激光制造前沿研究技术。阐述了基本作用原理、影响建模分析的因素和测试验证的方法。指出了各自的关键技术及研究焦点。介绍了国内外的相关研究进展。指出了在小批量多品种难加工材料成形与快速承载构件成形、复杂形面构件表面强化处理和微细构件高效加工方面的潜在用途。     

Effect of heating paths on strain distribution of plate in laser forming

In laser forming, a desired shape for a metal plate can be obtained by controlling a laser scan path and process parameters. The distance planned between parallel scan paths is larger in current laser path planning in order to avoid interference between them, and thus a continuous strain field cannot be formed. In addition, crossed heating lines are also adopted for forming complicated parts. The effects of the parallel and crossed scanning paths on the deformation field were investigated in this paper. The results show that for parallel heating lines, plastic strain fields produced by adjacent scans do not affect each other when the path spacing is greater than the laser spot diameter, but the plastic strain fields produced by the adjacent scans affect each other when the paths spacing is less than the laser spot diameter. A desirable continuous plastic strain field can be achieved by choosing appropriate path spacing and process parameters. For the crossed heating lines, the plastic strain field is different when adopting vertical and diagonal crossings. The influence between the different heating lines must be considered for high-precision laser forming.     

Error Compensation for Three-Dimensional Line Laser Scanning Data

In this paper, the problem of compensation of 3D line laser scanning data for improved inspection accuracy is addressed. This problem is important, as a 3D line laser scanner is about one order less accurate than a touch probe. The approach taken is to compensate through error characterisation. In other words, a software compensation is performed, instead of a hardware compensation, which is probably more expensive. To do so, the errors associated with a 3D line laser scanning system are first characterised. With error characterisation, an empirical formula is obtained relating the errors to the influencing factors including the projected angle and the scan depth. This empirical formula is used to compensate for the digitised surface data obtained by the corresponding laser scanning system. The results show that the proposed approach effectively improves inspection accuracy.     

Research on the forming process of three-dimensional metal parts fabricated by laser direct metal forming

To improve the forming quality of parts fabricated by laser direct metal forming (LDMF), the forming process of three-dimensional parts under open-loop LDMF system was studied in this paper. The influencing rule of scanning space on the forming quality was studied, and the optimal scanning space was derived. The software of control system about scanning style is also optimized, and thus, the forming quality of parts is improved. During fabricating three-dimensional parts, uneven heat distribution caused by multi-overlapping is one of the main factors affecting the sidewall forming quality. To solve the uneven heat distribution, the strategy of changing scanning speed was put forward. The influence of the standoff distance on the height of single-trace cladding layer was studied, and it was suggested that uneven surface of parts was caused by instability of process parameters, which could be compensated automatically in the condition of suitable standoff distance in the process of LDMF. Thus a so-called self-regulation effect is reached. Typical multi-overlapped parts with good forming quality are fabricated using the above-mentioned methods.     

激光工艺参数对改善编织摩擦材料性能的研究

利用激光扫描编织摩擦材料能明显提高其摩擦性能。采用正交试验设计的方法优化激光工艺参数,以激光电流、扫描速度、离焦量和扫描轨迹为试验因素。试验结果表明,影响编织摩擦材料的摩擦性能最主要因素是温度,激光扫描编织摩擦材料的最佳试验参数:激光电流为13.5 A、扫描速度为700 mm/m in、离焦量为2 mm、扫描轨迹是间距为0.5 mm的矩形波。揭示了激光扫描后编织摩擦材料热衰退机理。     

Experimental analysis and computer simulation of a methodology for laser focusing in the solar cell characterization by laser beam induced current

This paper presents a quick methodology for focusing a laser beam on a photoactive surface based on performing a single line scan while simultaneously modifying the laser's position over the surface and the distance between the focusing lens and the active surface. The methodology was tested using the computer simulation technique. Several configurations were computer simulated by programming different experimental situations to discover the situations in which this focusing methodology would provide optimum results. The conclusions obtained from computer simulation methodology were checked by means of experimental tests using several solar cells, such as a thin-film amorphous silicon solar cell, a monocrystalline silicon solar cell, and a polycrystalline silicon solar cell. From the tests performed, we concluded that optimum focusing is achieved in systems in which the laser beam induced current signal generated by the photoactive surface has no large heterogeneities (e.g., fingers or grain boundaries), artefacts, or defects. Thus, the best results are achieved in systems where the surface of the photovoltaic device has a certain degree of homogeneity.     

1Cr13不锈钢板激光弯曲数值模拟

在综合分析了材料的热物理性能和力学性能随温度变化影响的基础上,建立了板料激光弯曲成形的三维热力耦合模型.对1Cr13不锈钢钢板的激光单次扫描弯曲过程进行了数值模拟,得到了形变场、温度场以及应力场模拟结果,并对其变形过程和变形机理进行了分析.     

An experimental investigation on passive water cooling in laser forming process

The effect of passive water cooling in laser forming of thin sheets made of AISI 304 stainless steel is experimentally investigated. Indeed, since each laser scan can produce only small bending angles, multiple laser scans are required to produce a given deformation with a significant increase of production time due to cooling between consecutive scans. Therefore, passive water cooling is tested to verify its influence on minimum time between consecutive scans (cooling time), bending angle, and surface quality. A parametric approach is involved in the investigation and main process parameters are changed among the experiments by varying laser scanning speed, laser beam power, sheet thickness, and cooling media among several levels. It was discovered that the employment of passive water cooling in laser forming of thin sheets would be beneficial since the capability to dramatically reduce the cooling time and oxidation of both irradiated and cooled surfaces. In addition, the bending angle is only marginally affected by employment of water cooling. The effect of water cooling on stress and deformations are discussed by developing a numerical model based on finite element model.