KDP晶体表面质量主要影响因素的研究

针对KDP晶体超精密加工过程中出现的表面波纹度和粗糙度问题,采用二次通用回归旋转组合优化设计法及单点金刚石飞刀切削(SPDT)技术,对KDP晶体进行切削实验,对加工过程进行在线监测,利用多因素交互作用分析KDP晶体表面波纹度和粗糙度的影响规律。最后利用偏最小二乘法及lingo软件获得最佳加工工艺参数组合,即当刀具圆弧半径为9mm;转速为800 r/min;进给量为9.184μm/r;背吃刀量为21μm时,加工出KDP晶体的表面波纹度值为0.020μm,表面粗糙度值为0.017μm,对后续能够加工出更大口径(400×400)mm的高质量KDP晶体以满足航空航天领域应用具有重要的实际意义。     

KDP晶体单点金刚石超精密切削加工的发展

总结了KDP晶体材料优异的光学性能及其难加工的机械物理特性,并回顾了KDP晶体单点金刚石切削(SPDT)加工的起源,特别对KDP晶体SPDT加工技术的国内外发展状况做了着重介绍,最后展望了KDP晶体SPDT加工的未来发展趋势。     

KDP晶体塑性域切削技术研究

通过对KDP晶体等脆性材料压痕实验中的塑性行为分析,说明了实现KDP晶体等脆性材料塑性域切削的可行性.通过对脆性材料的切削模型进行分析,阐明了刀具几何尺寸以及切削用量对KDP晶体切削过程的影响.分析已有模型的不足,同时提出了从微观角度建立材料脆性断裂判据,以完善KDP晶体塑性域切削机理的研究思路.     

KDP晶体表面波纹度的分析与研究

针对工艺参数对KDP晶体表面波纹度值的影响问题,基于二次通用回归旋转组合方法优化KDP晶体单点金刚石飞刀切削工艺参数组合,采用单因素和多因素法分析各因素对表面波纹度的影响规律,并以此为基础优化工艺参数,进行KDP晶体切削实验。试验表明:各因素对表面波纹度的影响程度大小顺序为:进给量二次项、进给量、转速、转速与进给量的交互作用。优化出表面波纹度值最小时的加工工艺参数组合:刀具圆弧半径为9mm;转速为633r/min;进给量为11.8μm/r;背吃刀量为21μm,利用此组工艺参数加工出KDP晶体的表面波纹度为0.02μm。     

KDP晶体超精密加工切削力的实验研究

KDP晶体是一种常用的非线性光学材料,广泛应用于激光变频、电光调试和光快速开关等高技术领域。文中通过实验研究了KDP晶体超精密切削加工的切削力特性,分析了切削深度、进给量对切削力的影响,并对KDP晶体和铝合金的切削力进行了比较。研究结果表明,立轴平面铣削KDP晶体的切削力Fz、Fy随着切削深度和进给量的增加而增加,但增加的速度远小于铝合金的切削力Fz、Fy增加速度。实验证明了在生产实际中加工KDP晶体时,在不影响加工表面质量的前提下,可以适当加大切削深度和进给量,从而提高切削效率。     

飞刀加工蜗轮的切削干涉

文章对飞刀加工蜗轮过程中,飞刀实际切削后角的变化进行了分析,找出产生切削干涉的原因,并提出解决方法.     

高速加工切削参数对零件表面质量影响的工艺分析

通过对硬铝合金试件的高速铣削加工,研究了各种铣削参数的变化对加工表面质量的影响,以分析表面质量的形成机理,为今后高速铣削工艺研究提供一定的实践基础。     

KDP晶体微塑性域增强金刚石切削方法研究

针对KDP在SPDT切削过程中容易产生凹坑、划痕、裂纹等表面缺陷问题,提出利用热激励的方式增大KDP晶体塑性切削域深度,降低各向异性、机床运动误差、环境振动等因素对加工过程的影响,进而提高SPDT切削加工过程稳定性的方法。通过纳米压痕试验获得了KDP晶体表面在不同温度状态下的硬度和脆塑性转变深度变化规律,并在SPDT机床上采用金刚石刀具开展了KDP晶体飞切划痕实验,进一步验证了适当提高KDP晶体温度可以增大KDP晶体脆塑性转变临界切削深度。在此基础上,对KDP晶体开展了不同温度状态下的切削实验,实验结果表明在相同工艺参数下,随着温度的升高,表面粗糙度Sa值从3.2nm降低至1.6nm。     

KDP晶体超精密加工技术的研究

通过对KDP晶体等脆性材料的塑性域切削进行理论分析，研究实现脆性材料塑性域切削的条件。激光核聚变KDP晶体的3项主要技术指标是：表面粗糙度、波纹度和透射波前。通过分析影响这3项技术指标的因素。提出了实现KDP晶体精密加工的超精密机床和工艺参数。通过理论分析与实验。研究了晶向、刀具前角、刀具圆弧半径和进给量等参数对表面粗糙度的影响，最终给出KDP晶体精密加工的最佳工艺参数。     

切削参数对粗精铣合体刀具铣削加工表面质量的影响

采用硬质合金刀具,通过单因素实验对铸铝材料的表面铣削加工过程进行研究,获得最佳的切削参数,提高加工表面质量。实验以粗精铣一次完成工艺代替粗加工—精加工分步完成的加工工艺,研究粗精铣合体刀具加工中最佳的切削参数组合。实验结果表明,对于铸铝零件,切削加工的最佳切削参数组合为:切削速度v=3000r/min、进给量f=1000mm/min、背吃刀量a p=0.3mm。通过比较不同工艺下切削参数与表面质量之间的关系,得出在相同表面质量的要求下,粗精铣合体刀具在铣削过程可简化加工工艺,缩短加工时间。     

影响切削工件表面质量的因素分析及要因的检测系统设计

采用因果分析图等质量分析工具分析了影响切削加工工件表面质量的原因,并找出了影响表面粗糙度的主要因素是切削力、切削温度和机械设备振动.针对切削力和切削温度影响因素,将薄膜热电偶技术引入切削温度检测,设计了一套切削力和切削温度的完整检测系统.试验表明,该检测系统人机交互作用强,操作简单,使用方便.     

KDP晶体表面残留颗粒的机器视觉检测方法研究

KDP晶体是一种优质的非线性光学材料,广泛应用于激光核聚变等军工、国防领域。KDP晶体材质特殊,需采用超精密加工技术进行加工,加工过程中的杂质和抛光清洗液中的纳米级羰基颗粒容易吸附在其表面,对其光学特性影响很大。采用机器视觉技术检测晶体抛光清洗后表面残留颗粒,使用光学显微镜获取表面微观图像,经过图像存储、图像增强、边缘检测和图像分割等操作,将残留颗粒特征提取出来,然后进行图像标定、图像测量得到残留颗粒分布状态,对于评价KDP晶体清洗结果、指导清洗过程和保证晶体表面质量有重要作用。     

The design and optimization of micro polycrystalline diamond ball end mill for repairing micro-defects on the surface of KDP crystal

Micro-milling is a promising approach to repair the micro-defects on the surface of KH₂PO₄ (KDP) crystal. The geometrical parameters of micro ball end mill will greatly influence the repairing process as a result of the soft brittle properties of KDP crystal. Two types of double-edged micro ball end mills were designed and a three-dimensional finite element (FE) model was established to simulate the micro milling process of KDP crystal, which was validated by the milling experiments. The rake angle of −45°, the relief angle of 45° and the cutting edge radius of 1.5–2 μm were suggested to be the optimal geometrical parameters, whereas the rake angle of −25° and the relief angle of 9° were optimal just for micro ball end mill of Type I, the configuration with the rake angles ranging from 0° to 35°, by fully considering the cutting force, and the stress–strain distribution over the entire tool and the cutting zone in the simulation. Moreover, the micro polycrystalline diamond (PCD) ball end mills adopting the obtained optimal parameters were fabricated by wire electro-discharge machining (WEDM) and grinding techniques, with the average surface roughness Ra of tool rake face and tool flank face ∼0.10 μm, and the cutting edge radius of the tool ∼1.6 μm. The influence of tool's geometrical parameters on the finished surface quality was verified by the cutting experiments, and the tool with symmetric structure was found to have a better cutting performance. The repairing outlines with Ra of 31.3 nm were processed by the self-fabricated tool, which could successfully hold the growth of unstable damage sites on KDP crystal.     

ELID镜面磨削硬质合金的工艺参数实验研究

随着国防尖端技术的迅速发展,许多具有独特性能的新材料得到了日益广泛的应用,如光学玻璃、硬质合金。但采用传统磨削工艺加工这些材料很难得到良好的表面质量。在线电解砂轮修整(ELID)磨削技术是一项新的、高效的磨削方法,它有效地实现了许多难加工材料的超精密加工和高效加工。针对硬质合金的特性,用ELID磨削方法应用于硬质合金的精密加工,通过实验研究ELID磨削中工艺参数对加工表面的影响规律,找到了在一定条件下优化的工艺参数。     

A study on ultra–high-speed cutting of aluminium alloy:: Formation of welded metal on the secondary cutting edge of the tool and its effects on the quality of finished surface

To investigate the mechanism of ultra–high-speed cutting for aluminium alloy, cutting experiments by using a machine tool equipped with an active magnetic bearing spindle were performed over a range of cutting speeds from 20 to 260 m/s. On the whole, the finished surface tends to improve with an increase in cutting speed. However, the formation of welded metal on the tool edge in the speed range from 100 to 200 m/s promotes the material side flow on the finished surface, which causes the surface roughness to increase.     

Cutting surface quality analysis in micro ball end-milling of KDP crystal considering size effect and minimum undeformed chip thickness

Potassium dihydrogen phosphate (KH₂PO₄ or KDP) crystal is a typical soft-brittle optical crystal, and the size effect and brittle cutting mode are easy to appear in micro ball end-milling of KDP crystal. In this paper, micro-grooving experiments are conducted to study the size effect and brittle cutting in micro ball end-milling of KDP crystal with different feed rate and depth of cut. The cutting force, machined groove base quality and chip morphology are collected and analyzed carefully. The size effect is discovered by the phenomena of the existence of oscillations and relaxations in cutting force and hyper-proportional increase of specific cutting force, when the ratio of feed per tooth to cutting edge radius f_t/r_e is less than 1. While the brittle cutting mode is detected through the existence of sharp fluctuations in cutting force and cracks on the groove base when the ratio f_t/r_e is larger than 2. From the further comprehensive analysis of cutting force, specific cutting force, machined groove base quality and chip morphology, the cutting parameters with ratios of the maximum undeformed chip thickness in one cutting circle to cutting edge radius h_max/r_e around 0.14, 0.2 and 0.4 are regarded as size effect, optimal and brittle cutting points, respectively. The size effect, ductile cutting and brittle cutting zones are divided by the size effect and brittle cutting boundaries (points). Among the optimal points, the depth of cut of 2 μm with the ratio f_t/r_e of 1 is the optimal cutting parameter for micro ball end-milling of KDP crystal.     

切削参数对切削力影响的实验分析

通过切削试验。分析了切削速度、背吃刀量以及切削液等参数改变时，对切削力及表面质量的影响。     

难加工材料干切削表面粗糙度试验研究

针对难加工材料干切削的加工质量问题,应用正交试验法,找出了影响难加工材料干切削表面粗糙度的主要因素。同时,初步探讨了加工前表面粗糙度和加工后表面粗糙度的关系。试验证明:该方法能够保证难加工材料的切削质量和达到切削参数优选的目的,对实际生产具有指导意义。     

Effects of cutting edge geometry, workpiece hardness, feed rate and cutting speed on surface roughness and forces in finish turning of hardened AISI H13 steel

In this study, the effects of cutting edge geometry, workpiece hardness, feed rate and cutting speed on surface roughness and resultant forces in the finish hard turning of AISI H13 steel were experimentally investigated. Cubic boron nitrite inserts with two distinct edge preparations and through-hardened AISI H13 steel bars were used. Four-factor (hardness, edge geometry, feed rate and cutting speed) two-level fractional experiments were conducted and statistical analysis of variance was performed. During hard turning experiments, three components of tool forces and roughness of the machined surface were measured. This study shows that the effects of workpiece hardness, cutting edge geometry, feed rate and cutting speed on surface roughness are statistically significant. The effects of two-factor interactions of the edge geometry and the workpiece hardness, the edge geometry and the feed rate, and the cutting speed and feed rate also appeared to be important. Especially honed edge geometry and lower workpiece surface hardness resulted in better surface roughness. Cutting-edge geometry, workpiece hardness and cutting speed are found to be affecting force components. The lower workpiece surface hardness and honed edge geometry resulted in lower tangential and radial forces.     

Study of cutting force and surface roughness in the turning of polytetrafluoroethylene composites with a polycrystalline diamond tool

Despite the importance of the polytetrafluoroethylene (PTFE) composites in many industrial applications, especially for space industry, very little is known about the machinability of these composites. This paper presents an investigation into the turning of PTFE composites using a polycrystalline diamond tool in order to analyze the effect of the cutting parameters and insert radius on the cutting force and surface roughness. A strain gauge based dynamometer for the main cutting force measurement in turning was constructed. The force signals were captured and processed using a strain data acquisition system based on the Sider8 and CATMAN software. Cutting force and surface roughness were measured through longitudinal turning, according to the experimental plan developed based on the Taguchi methodology. The signal-to-noise ratio and the analysis of variance were applied to the experimental data in order to determine the effect of the process variables on the surface roughness and cutting force, and predictive models have been derived.