纵-扭复合振动超声深滚加工工艺试验

采用正交试验法对Q235钢端面进行了纵-扭复合振动超声深滚加工,探索了工艺参数对表面粗糙度和显微硬度的影响,并基于试验结果构建了表面粗糙度和显微硬度的预测模型。试验结果表明：经纵-扭复合振动超声深滚加工后,工件表面粗糙度值显著减小,而显微硬度有大幅提高;表面粗糙度值随静压力增大先增后减,随进给量的增大而急剧增大,而随滚压速度的增大变化不明显,且进给量对表面粗糙度的影响最显著;显微硬度随静压力的增大而提高,随进给量和滚压速度的增大有微小波动,且静压力对显微硬度的影响最显著;基于t-检验与相关系数计算结果发现,进给量与静压力的交互作用对表面粗糙度的影响最大,而静压力与滚压速度的交互作用对显微硬度的影响最大。基于正交试验结果和预测模型获得了最优工艺参数,两者的结果接近,表明预测模型可靠。     

无心车床车削钛合金棒材工艺参数与表面粗糙度关系研究

采用无心车床对钛合金棒料进行表面处理,以去除其表面缺陷,降低表面粗糙度,研究车削工艺参数主轴转速V、进给速度F、吃刀量a_p对表面粗糙度的影响规律。利用响应曲面法来设计实验,通过对实验数据的回归分析,建立基于加工工艺参数(主轴转速、切削深度、进给速度)表面粗糙度预测模型;分析车削工艺参数及其交互作用对表面粗糙度的影响规律,获得了车削最优工艺参数区间。研究结果表明:车削工艺参数对工艺指标表面粗糙度的影响次序为:a_pfV。在工艺参数交互作用中,f-a_p的交互作用对表面粗糙度影响最大;在最优车削工艺参数区间确定的工艺参数组合可满足表面粗糙度R_a小于0.8μm的生产要求。     

车削参数对A100钢表面粗糙度的影响

为研究车削参数对A100钢表面粗糙度的影响规律,采用硬质合金刀具对A100钢进行了正交车削试验,分析了各车削参数对表面粗糙度的影响规律及显著程度,并构建了表面粗糙度的多元线性回归模型。结果表明:表面粗糙度随进给量和切削深度的增大而增大,随主轴转速的增大而减小。其车削参数对表面粗糙度的影响主次顺序为:f ap n,并通过回归模型显著性分析验证了回归模型的准确性。     

GH4169高速车削参数对加工表面完整性影响研究

使用PVD-TiAlN涂层硬质合金刀片进行高温合金GH4169的高速车削正交试验,建立了表面完整性特征中表面粗糙度、表面残余应力、显微硬度的经验公式,分析了车削参数对表面完整性各特征量的影响规律,并观测了高速车削加工的表面形貌。结果表明:表面粗糙度随车削速度的增加而减小,随进给量和切削深度的增加而增大,进给量是影响表面粗糙度的最主要因素;随着进给量的增加,表面形貌变差;轴向残余应力表现为压应力,切向残余应力表现为拉应力,减小进给量,降低车削速度可减小车削加工的残余应力,轴向残余应力对进给量最敏感,切向残余应力对切削深度最敏感;显微硬度随车削速度的增大而增加,车削速度是影响显微硬度的主要因素。     

车削参数对难加工材料表面粗糙度的影响及参数优化

为了研究车削参数对难加工材料(300M钢、A100钢及TC18钛合金)表面粗糙度的影响规律以及优化车削参数,首先采用硬质合金刀具对难加工材料进行正交车削试验,依据试验结果分析车削参数对表面粗糙度的影响规律及显著性;然后构建表面粗糙度的多元线性回归模型;最后以材料最大去除率和最小表面粗糙度为评价指标,对车削参数进行多目标函数优化分析.结果 表明:难加工材料的表面粗糙度随切削速度的增加而减小,随进给量的增加而增加,随背吃刀量的增加而增加,且A100钢的表面粗糙度远大于300M钢的表面粗糙度,TC18钛合金的表面粗糙度与300M钢的表面粗糙度相差较小;进给量对难加工材料表面粗糙度的影响程度最大,背吃刀量次之,切削速度对其影响程度最小.获得了难加工材料在满足不同工艺要求下的最优车削参数组合.     

车削参数对难加工材料表面粗糙度的影响及参数优化

为了研究车削参数对难加工材料(300M钢、A100钢及TC18钛合金)表面粗糙度的影响规律以及优化车削参数,首先采用硬质合金刀具对难加工材料进行正交车削试验,依据试验结果分析车削参数对表面粗糙度的影响规律及显著性;然后构建表面粗糙度的多元线性回归模型;最后以材料最大去除率和最小表面粗糙度为评价指标,对车削参数进行多目标函数优化分析.结果 表明:难加工材料的表面粗糙度随切削速度的增加而减小,随进给量的增加而增加,随背吃刀量的增加而增加,且A100钢的表面粗糙度远大于300M钢的表面粗糙度,TC18钛合金的表面粗糙度与300M钢的表面粗糙度相差较小;进给量对难加工材料表面粗糙度的影响程度最大,背吃刀量次之,切削速度对其影响程度最小.获得了难加工材料在满足不同工艺要求下的最优车削参数组合.     

CBN刀具车削淬硬钢表面粗糙度的试验与预测

利用正交设计方法,对立方氮化硼(CBN)刀具硬态干式车削淬硬钢Cr12Mo V时,切削用量三要素(切削速度、进给量和切削深度)对加工表面粗糙度的影响进行了分析,运用响应曲面法(RSM)建立了加工表面粗糙度的预测模型。研究结果表明:CBN刀具车削淬硬钢Cr12Mo V时对加工表面粗糙度影响最大的加工参数是切削速度,其次是进给量,切削深度对加工表面粗糙度的影响较小;预测模型能够高精度地对表面粗糙度进行预测,平均误差不超过9.7%。     

滚挤压方法在孔精加工中的应用

正滚挤压加工是一种对工件表面进行光整和强化的无切屑加工工艺,具有显著降低工件表面粗糙度值和改善工件质量的作用。其加工原理是利用金属在常态下的冷塑性特点,应用特制滚、挤压工具(刀具)对工件表面施加一定的压力,使金属表面产生塑性变形,修正工件表面微观不平度,降低工件表面粗糙度值,改善表面金相组织,形成有利的残余应力分布,从而提高零件的机械性能和使用寿命。滚挤压加工工艺特点为:(1)加工表面粗糙度值低,可达0.08~0.32μm,加工精度可达IT5~IT6级公差。     

EA4T车轴车削表面完整性研究

基于EA4T车轴车削正交试验,研究了车削加工工艺参数对车轴表面粗糙度、残余应力分布等表面质量完整性的影响规律,并进行了工艺参数优选。研究结果表明:工艺参数对加工表面粗糙度、轴向与周向残余应力产生较显著影响,且工艺参数对表面粗糙度和残余应力具有相似的影响规律,其中进给量是对加工表面完整性影响最显著的因素。     

切削参数对高强铝合金干切削加工表面形貌的影响

为在高强铝合金干切削加工工艺制定时提供参考,设计了正交试验,并选用YBG102纳米涂层细颗粒合金刀具干式切削高强度铝合金7075-T6,分析了不同切削参数条件对已加工表面形貌的影响规律。结果表明:进给量是影响表面粗糙度的主要因素,其次是切削深度,最后是切削速度;在保障切削效率条件下,获得较好表面粗糙度的最佳工艺参数组合为较高切削速度、中等切削深度、较小进给量;三维表面轮廓高度较难通过切削三要素调控,但表面峰值占最大高度百分比受进给量和切削深度的影响较为明显。     

Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel

The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.     

Ball burnishing of tool steel

In place of the traditional methods of finishing a surface, the ball-burnishing process was investigated. Experimental work was conducted on a vertical machining center to establish the effects of various burnishing parameters on the surface finish of ASSAB XW-5 steel (high-carbon, high-chrome steel), including burnishing speed, ball material, lubricant, burnishing forces (depth of penetration), and feed. Within the parameter space explored, it was found that the burnishing speed affects the surface finish, with a burnishing speed of 1,200 mm/min giving the worst surface finish. WC (Tungsten carbide) ball gave the best and most consistent surface finish. Grease was a better lubricant than cutting oil. By varying the burnishing speed, the burnishing forces varied also, and these forces showed no obvious relationship to the surface finish of the burnished workpiece.     

Prediction of surface characteristics obtained by burnishing

To reduce the irregularities of machined surface, burnishing is used as a finishing process by plastic deformation. This process does not only improve surface finish but also generates compressive residual stresses throughout the surface. In this work, an analytical study and a finite element modelling were performed to provide a fundamental understanding of the burnishing on an AISI 1042 workpiece. The analytical results were concentrated on the surface roughness and on some burnishing parameter effects. The simulations were devoted to the study of the surface profile, the residual stresses and the influence of burnishing parameters (penetration depth, feed rates, diameter of the ball of burnishing tool and initial surface quality) on surface roughness and the residual stress distribution. It has been noted that burnishing improves surface quality and introduces compressive residual stresses. These results were successfully compared to experimental data obtained in previous works.     

Analysis and optimization of the ball burnishing process through the Taguchi technique

In the present study, the analysis and optimization of the ball burnishing process has been studied. The Taguchi technique is employed to identify the effect of burnishing parameters, i.e., burnishing speed, burnishing feed, burnishing force and number of passes, on surface roughness, surface micro-hardness, improvement ratio of surface roughness, and improvement ratio of surface micro-hardness. Taguchi tools such as analysis of variance (ANOVA), signal-to-noise (S/N) ratio and additive model have been used to analyse, obtain the significant parameters and evaluate the optimum combination levels of ball burnishing process parameters. The analysis of results shows that the burnishing force with a contribution percent of 39.87% for surface roughness and 42.85% for surface micro-hardness had the dominant effect on both surface roughness and micro-hardness followed by burnishing feed, burnishing speed and then by number of passes.     

Investigation of the burnishing process with PCD tool on non-ferrous metals

It is well known that the no-chip machining process, burnishing, can easily improve surface roughness, waviness and hardness. To get the practical useful parameters, the effects of various burnishing parameters (spindle speed, depth, feed, burnishing radius and lathe) on surface roughness and waviness of the non-ferrous components were studied experimentally with a theoretical analysis. The experiments were conducted with a simply designed cylindrical surfaced polycrystalline diamond tool developed by us. It was found that smaller parameters do not mean lower surface roughness or waviness and different optimum burnishing parameters can be got under different burnishing conditions.     

The use of D-optimal design for modeling and analyzing the vibration and surface roughness in the precision turning with a diamond cutting tool

Using a diamond cutting tool in the precision turning process, the vibration of tool-tip has an undesirable effect on the machined surface??s quality. The objective of this paper is to present the mathematical models for modeling and analyzing the vibration and surface roughness in the precision turning with a diamond cutting tool. Machining parameters including the spindle speed, feed rate and cutting depth were chosen as numerical factor, and the status of lubrication was regarded as the categorical factor. An experimental plan of a four-factor??s (three numerical plus one categorical) D-optimal design based on the response surface methodology was employed to carry out the experimental study. A micro-cutting test is conducted to visualize the effect of vibration of tool-tip on the performance of surface roughness. With the experimental values up to a 95% confidence interval, it is fairly well for the experimental results to present the mathematical models of the vibration and surface roughness. Results show that the spindle speed and the feed rate have the greatest influence on the longitudinal vibration amplitude, and the feed rate and the cutting depth play major roles for the transverse vibration amplitude. As the spindle speed increases, the overall vibration of tool-tip tends to more stable condition which leads to the results of the best machined surface. The effects of the feed rate and cutting depth provide the reinforcement on the overall vibration to cause the unstability of cutting process and exhibit the result of the worst machined surface.     

Influence of burnishing process on surface roughness,hardness, and microstructure of some non-ferrous metals

Burnishing is a cold working process, which easily produces a smooth and work-hardened surface by plastic deformation of surface irregularities. In the present work, the influence of the main burnishing parameters (speed, feed, force, number of tool passes, and ball diameter) on the surface roughness and the hardness of two different non-ferrous metals were studied. Furthermore, subsurface hardness and microstructure under specific conditions were also studied. It was found that the burnishing forces and the number of tool passes are the most pronounced parameters, which have great effects on the workpiece's surface during the burnishing process. A simple, inexpensive and newly designed ball-burnishing tool, with interchangeable adapter for using different ball diameters, was used throughout the experimental work presented in this paper.     

Analysis and prediction of tool wear, surface roughness and cutting forces in hard turning with CBN tool

The main of the present study is to investigate the effects of process parameters (cutting speed, feed rate and depth of cut) on performance characteristics (tool life, surface roughness and cutting forces) in finish hard turning of AISI 52100 bearing steel with CBN tool. The cutting forces and surface roughness are measured at the end of useful tool life. The combined effects of the process parameters on performance characteristics are investigated using ANOVA. The composite desirability optimization technique associated with the RSM quadratic models is used as multi-objective optimization approach. The results show that feed rate and cutting speed strongly influence surface roughness and tool life. However, the depth of cut exhibits maximum influence on cutting forces. The proposed experimental and statistical approaches bring reliable methodologies to model, to optimize and to improve the hard turning process. They can be extended efficiently to study other machining processes.     

Using specially designed high-stiffness burnishing tool to achieve high-quality surface finish

This paper is focused on the process of ball burnishing. The influence of tool stiffness on surface roughness parameters was considered theoretically, while experimental investigation was conducted to establish the influence of initial surface roughness (previous machining) on the effects of ball burnishing as the finishing process. Experimental investigations were conducted over a wide interval of most influential process parameters (burnishing forces, burnishing feed, and number of burnishing passes). The material used in the experiments was aluminum alloy EN AW-6082 (AlMgSi1) T651. Burnishing was performed using a specially designed tool of high stiffness. Statistical analysis of experimental data revealed strong correlation between roughness, R _a, and burnishing force, burnishing feed, and number of passes for the three surfaces, each with different roughness parameters. Particular combinations of process parameters yielded very low surface roughness, R _a, equivalent to polishing. It is worth noting that high surface quality can be achieved with relatively small burnishing forces, which differs from the investigations published so far. Contrary to conventional approaches, which are based on elastic tool systems, the authors propose the burnishing process to be conducted with high-stiffness tools. Further investigation shall be focused on optimization of burnishing process parameters in order to achieve surface finish equivalent to high polish.     

Influence of machining parameters on the machinability of particulate reinforced Al/SiC–MMC

The paper presents the result of an experimental investigation on the machinability of silicon carbide particulate aluminium metal matrix composite during turning using a rhombic uncoated carbide tool. The influence of machining parameters, e.g. cutting speed, feed and depth of cut on the cutting force has been investigated. The influence of the length of machining and cutting time on the tool wear and the influence of various machining parameters, e.g. cutting speed, feed, depth of cut on the surface finish criteria has been analyzed through the various graphical representations. The combined effect of cutting speed and feed on the flank wear has also been investigated. The influence of cutting speed, feed and depth of cut on the tool wears and built-up edge is analyzed graphically. The job surface condition and wear of the cutting tool edge for the different sets of experiments have been examined and compared for searching out the suitable cutting condition for effective machining performance during turning of Al/SiC-MMC. Test results show that no built-up edge is formed during machining of Al/SiC-MMC at high speed and low depth of cut. From the test results and different SEM micrographs, suitable range of cutting speed, feed and depth of cut can be selected for proper machining of Al/SiC-MMC.