SiCp/Al composites are widely used in aerospace, optical devices, electronic devices and other fields due to their excellent properties such as wear resistance, high specific strength and low thermal expansion coefficient. Due to the difference between the constituent phases of SiCp/Al composites and the high hardness of SiC particles, conventional milling (CM) leads to problems such as poor processing quality and severe tool wear. Ultrasonic vibration-assisted milling (UVAM) can achieve high-quality cutting of SiCp/Al composites. However, the relationship between constituent phases (SiC particles, Al matrix) and tool under ultrasonic vibration is complex and the research depth is insufficient. This paper focuses on the study of the interaction between the constituent phase of SiCp/Al composites and the tool in UVAM. The formation process of residual cutting zone and material removal mechanism in ultrasonic machining were analyzed, and the influence of ultrasonic vibration on the removal mechanism of SiCp/Al composites was explored from the aspects of tool cutting speed and tool kinetic energy. A three-dimensional micro-cutting model of SiCp/Al composite multi-particles was established, and the interaction between constituent phases and tool during cutting under different ultrasonic amplitude conditions was analyzed by finite element method and combined with a series of experiments. The results show that the introduced ultrasonic vibration increases the kinetic energy of the tool and improves the tool's ability to damage SiC particles and Al matrix. Compared with CM, UVAM significantly reduces surface pits, scratches, and SiC particle crushing defects, and the surface roughness Sa is reduced by 32.33%. Tool wear is relieved, and the wear of the back tool face is reduced by 22.31% at most. At the same time, the resultant milling force is also decreased 32.76%. In short, the research in this paper is of great significance to improving the high-quality processing of SiCp/Al composites.

C/SiC composites have excellent mechanical properties such as high specific strength and high temperature resistance, and are widely used in aerospace fields. However, due to its special structure and material properties, the tool wear is severe when machining with conventional methods, and the processing quality is poor. The purpose of this paper is to reveal the progressive wear behavior, wear mechanism of the tool, and its effect on machining performance in conventional milling (CM) and ultrasonic vibration-assisted milling (UVM) of C/SiC composites under forward fiber cutting (FC) and reverse fiber cutting (RC). The material removal and heat transfer models were established, and the stress distribution characteristics of cutting -edge were analyzed by finite element method (FEM). Combined with the wear morphology, cutting heat, and cutting force, the tool wear behavior and mechanism in UVM and CM under FC and RC were studied, and their effects on machining quality were analyzed. The results show that there are great differences in heat transfer and removal process between FC and RC. In UVM, the introduction of ultrasonic vibration reduces the adhesion of fine chips, weakens the strong friction and scratching between the hard chips and the cutting -edge, and alleviates the tool wear. The flank wear VB and cutting -edge wear area WA in RC are larger than those in FC, the abrasive wear is intensified, the material even peeling under mechanical shock, and the adhesive wear is more serious. When the tool wear intensifies to a certain extent, the difference of the cutting process caused by mechanical anisotropy of C/SiC composites is weakened, and the surface micro-defects and surface roughness Sa change little under FC and RC. This research contributes to the realization of high-quality and low-cost processing of C/SiC composites.

浇注系统的流动平衡设计是一模异穴注塑模具设计的重点和难点,其设计多依据工程人员经验,易造成模具整体设计效率的低下,本文以某型充电宝(外观自主开发)塑料外壳为例,设计了充电宝塑料外壳组成的一模异穴布局的浇注系统,基于CAE分析技术,从浇注系统的充填时间、V/P切换点压力、注射位置处压力三个关键评价指标对初始浇注系统设计方案进行分析;以浇注系统中的各级流道的截面尺寸作为优化设计目标,基于Moldflow软件中的流道平衡分析技术对各级流道的尺寸进行迭代优化计算.优化后的浇注系统有效改善了熔体的充填不平衡.优化结果表明:一模异穴型腔充填的时间不平衡率3.51%,压力不平衡值为3.86 MPa,满足充填时间的不平衡率低于5%,压力不平衡值小于5 MPa的要求.通过实际的注塑生产验证,获得的注塑产品质量合格,可为一模异穴结构的模具浇注系统设计提供借鉴.

刀具磨损不仅影响工件加工表面质量和加工精度,而且频繁地换刀还会降低加工效率、增加生产成本,通过研究刀具磨损机理,影响刀具磨损的因素以及刀具磨损预测模型建模技术,为降低刀具磨损提供技术支持.对切削加工过程中刀具磨损及其预测建模技术的研究进展进行了综述.首先,基于近年来刀具磨损机理研究进展,分别对几种主要刀具磨损机理的表现形式及特征进行了分析.其次,重点论述了切削加工过程中切削参数、刀具几何参数、刀具和工件材料特性及加工方法等因素对刀具磨损影响规律,总结分析了刀具磨损预测建模方法和形式.最后,结合制造业绿色节能的发展理念和高速发展的计算机技术,指出降低刀具磨损的加工方法和刀具磨损预测建模技术的未来发展方向.

The roughness and material removal difference ofCr12MoV high strength structural steel under different process parameters during magnetic electrolytic milling were discussed by orthogonal test method. Principal component analysis and grey correlation algorithm were used to construct the grey correlation degree between roughness and material removal amount,so as to complete the multi-objective optimization in the way of single objective optimization. With the continuous improvement of grey correlation degree,the optimal process parameters were obtained:the number of abrasive mesh was 250 mesh,the speed of magnetic pole was 550r/min,and the mass ratio of two phases was 3:1.The predicted result of grey correlation degree is close to the experimental value,and the two show a similar trend. The fitting degree is 97.62%,which can meet the reliability requirements. The roughness Ra of the optimized treatment is reduced by 13.04% and the material removal amount Δm is increased by 11.34%. The accuracy of the results can be guaranteed by using the multi-objective optimization in this paper. The research has a very good practical guiding value for improving the machining accuracy of magnetic electrolysis milling and is easy to be popularized and applied.

刀面微织构改变了刀具与切屑之间的摩擦状态,表面微织构刀具在切削中能够降低刀具磨损、提高刀具寿命和切削性能,研究表面微织构刀具的切削加工技术具有重要意义.通过对表面微织构刀具切削加工技术进行综述,介绍了表面微织构刀具制备方法以及表面微织构刀具在切削加工过程中的切削力、切削温度、刀具磨损、工件加工表面粗糙度的影响规律,梳理了表面微织构在不同刀具上的应用,对表面微织构刀具切削加工技术的未来发展趋势进行了展望.

The anisotropy, heterogeneity, and high hardness of C-f/SiC composite bring great difficulties to its efficient and high-quality processing. Ultrasonic vibration-assisted milling (UVAM) has been shown to positively affect the machining quality of C-f/SiC. This work focuses on the effect of ultrasonic amplitude on 3D needle-punched C-f/SiC composites machining under different fiber cutting angles, and few related studies have been reported. By analyzing the simplified cutting model for both forward and reverse cutting, the influence of ultrasonic amplitude on tool-fiber contact characteristics was investigated. Under fiber cutting angles of 0(circle), 45(circle), 90(circle), and 135(circle), finite element simulations based on the orthogonal cutting model and UVAM experiments with different amplitudes were performed. The results showed that the alternating friction force caused by the harmonic vibration promoted the damaging effect of the tool on the fiber and SiC matrix. At 0(circle) and 135(circle), localized fiber failure occurred early. And at 45(circle) and 90(circle) the shear failure of the fiber was strengthened, which alleviated the damage to the low-strength matrix and the interface layer. Compared with conventional milling, the resultant force showed a downward trend, and typical defects such as pits, fiber pullout, matrix voids, and interface debonding on the machined surface were suppressed in UVAM. As the amplitude increased, the machined surface became smoother, and the surface roughness Sa at all angles decreased by more than 30%. According to the response surface method, the influence order of machining parameters on Sa was obtained: feed rate > amplitude > cutting speed. Sa predictive regression model with only a 5% deviation from the experimental value has good accuracy and reliability. This work shows that reasonable control of ultrasonic parameters and fiber cutting angle in UVAM significantly affects the machining quality improvement of 3D needle-punched C-f/SiC components.

In this paper, through a series of grinding experiments with different machining parameters on the surface of the workpiece, the surface roughness under different machining parameters are obtained The surface roughness prediction model is constructed by the response surface method. The effects of feed rate, amplitude, and spindle speed on the surface roughness are analyzed. The results show that the surface quality of ultrasonic-assisted grinding is better than that of conventional grinding. Amplitude has the most prominent effect on the improvement of surface quality, followed by the spindle speed. The feed rate has little effect on the surface roughness. The model can predict 93.71% of the experimental results and the prediction error of the model is lower than 5%.

高速切削加工参数选择不合理会导致切削振动,切削过程中振动引起的不稳定切削会产生一系列不良的影响,切削振动的预测将有助于优化高速切削加工过程,提高切削加工表面质量和加工效率.概述了高速切削加工过程中颤振产生的机理与类型,并分析了切削颤振的影响因素;对切削加工过程稳定性预测进行了报道,重点论述了切削稳定性的影响因素;对切削振动辨识与预测方面的研究成果进行了总结.指出了切削加工过程振动预测技术的未来发展趋势.

Cemented carbide has huge applications in industrial production, but its high mechanical properties also increase the difficulty of processing. In this work, ultrasonic vibration-assisted grinding technology is used for the precision manufacturing of cemented carbide. The influence of the dynamic trajectory of the grains on the material removal process is analyzed. The morphology and roughness of the processed surface are measured and studied. It was observed that in the conventional grinding, the blade pattern is obvious with some defects on the surface. While in the ultrasonic vibration-assisted grinding, the material surface is mainly distributed with pits and small protrusions, and there is no obvious blade pattern. According to the roughness test, the roughness of ultrasonic vibration-assisted grinding is better than that of conventional grinding, and the increase in amplitude has a significant effect on the improvement of roughness. When the amplitude increases from 3μm to 9μm, the surface roughness is improved about 38.1%. The research of ultrasonic vibration-assisted grinding should be of great importance for promote the high-efficiency and high-quality processing and special applications of cemented carbide.

7075 aluminum alloy is widely used due to its great performance, especially in aerospace area. In this paper, ultrasonic-assisted grinding technology is used to process 7075 aluminum alloy. The data is obtained through experiments, and the surface roughness and morphology of ultrasonic assisted grinding and conventional grinding under different spindle speeds, feed rates, and amplitudes are analyzed. Research has found that the increase in spindle speed and amplitude will improve the quality of the machined surface and reduce the surface roughness by 82.1% and 36%. However, with the increase of feed rate, the surface quality decreased significantly, and the surface roughness increased by 55.6%. The surface micro-morphology of the machined workpiece is observed, and the effects of different processing parameters on the surface micro-morphology are obtained.

切削加工表面存在的裂纹、凹坑等缺陷会降低零件的疲劳强度和耐腐蚀性,引起零件过早的损坏,研究缺陷的生成机理,提出有效的加工表面缺陷的预测方法,对提高产品的质量以及保证产品生产效率具有重要意义.阐述了加工表面缺陷的生成机理,分析了加工参数对表面缺陷的影响;总结了现有的缺陷统计分析与预测的研究成果,综述了表面缺陷对工件耐腐蚀性的影响.

表面粗糙度对零件的使用寿命有很大影响,正确、合理地选用表面粗糙度数值,可以减少零件的加工费用,提高零件的使用寿命.对表面粗糙度的评定参数及测量方法进行了介绍,重点阐述了表面粗糙度的产生机制和切削参数对表面粗糙度的影响;从回归分析法、响应曲面法和神经网络建模方法3个方面综述了表面粗糙度预测与建模的研究进展.指出用多参数表征表面粗糙度和建立加工表面粗糙度的预测、优化和工艺工况为一体的综合预测模型是未来发展方向.

The chatter in cutting process has a significant influence on production efficiency, processing quality, machining environment, costing and the lifetime of machine and cutting tools. The mathematical models of dynamic cutting force and cutting system dynamics in the cutting process were established by analytical method. The prediction of system stability limit in the multi-parameter hard turning process was made in the way of numerical simulation. The parameters taken into consideration include the spindle speed, the cutting width, the feed rate, the corner radius and the hardness of work-pieces. The critical conditions of the stable cutting in experimental high speed precision hard cutting system were computed. The results of predictions about stability limits were verified, which conform to actual measurement. The cutting chatter appears more easily, when the hardness of the workpieces is higher, the corner radius is bigger or the feed rate is smaller. [Submitted 25 December 2016; Accepted 29 August 2017]

培养高质量创新创业型人才,提升工程领域的竞争力已经成为高等教育领域的热门课题.对高校创新创业教育实践模式进行探讨,分析了我国目前创新创业教育存在问题;从政策支持、课程体系建设、教育形式改革、优化教育机制、 师资队伍建设和提高服务水平等几方面,提出了深化创新创业教育改革的途径.

针对硬币流通广泛,且流通过程中存在不易清点等特点,在原有的硬币清分计数装置基础上,设计开发了一种新型的动静筛板硬币清分计数机.利用不同币值硬币的直径大小不同,实现硬币的清分;然后通过光电传感器对硬币数量进行统计.

本文对应用型本科卓越工程师校企联合培养模式进行了探讨,分析了我国校企联合培养卓越工程师教育模式存在的问题,讨论了卓越工程师在西方国家的培养模式;并在策略与法律法规、企业积极性、课程改革和师资队伍建设等方面提出了相关对策建议.

Under some conditions, there are more serious plastic flow measurements, have a great effect on surface roughness, on the surface which is formed by hard cutting. A mathematical model, explained the relationship between surface plastic flow measurement and surface roughness, was established. The dependence of formed of surface plastic flow measurement on feed rate, corner radius and other factors was researched by finite element, simulation cutting test and observing the surface of workpiece microscopic. All the increase of the hardness of workpiece material, cutting temperature and cutting force, is vertical with the surface of workpiece, will reduce the height of plastic flow measurement. With the decrease of feed rate and the increase of corner radius, the surface roughness will decrease, meanwhile, the degree of plastic flow measurement aggravates. Effected by the plastic flow measurement, after the feed rate reduces to 0.036 mm/r, an increase trend will be shown.

加强校企合作是本科高校培养高素质应用型人才的重要方法和途径.文章介绍了校企合作模式培养应用型人才的特点、存在的问题及其原因分析和解决办法,并进行了校企合作应用型人才培养模式的实践与探索,校企合作模式有利于实现企业、学校和学生的三方共赢,符合地方本科院校的办学理念和应用型人才的培养目标.

Abstract: Corner radius as a non-main cutting parameters, study of corner radius about cutting vibration is relatively small.Turning experiments use PCBN tool in CAK4085 CNC lathe,cutting hardened steel HRC50-52 Cr12MoV and hardened steel HRC62-64 GCr15, eddy current sensor measure the tool vibration amplitude of each group parameters, analysis influence of the corner radius for tool vibration amplitude. With corner radius increases, tool vibration amplitude increases. Research will contribute to the development of high-speed machining of hardened steel.