An experimental study on machining techniques of cutting composite armors

The machining of laminated composite components or armors consisting of engineering ceramics, fiber-reinforced plastic, and even aluminum or titanium alloy is a great challenge to manufacturing engineers. So far, quite limited literatures can be found concerning the machining of laminated composite components, and the quite limited studies are mainly focused on the stacks consisting of metal plates and composite materials. Also, there is hardly any report concerning the cutting techniques of laminated composite components or armors. In this work, the cutting techniques of three types of composite armors such as the Kevlar fiber-reinforced plastic (KFRP) protection inner lineplate, the ceramic composite armor (ceramics/glass fiber-reinforced plastics/aluminum alloy laminate), and the double-plate composite armor (ceramics/KFRP laminate) were studied experimentally on a desktop cutting machine, using a sintering diamond saw. Two types of machining processes such as cocurrent cutting and reverse cutting were discussed, and finally, reverse cutting is recommended for better cutting quality. Cutting tests indicated that under proper processing conditions, high-quality cutting of composite armors can be carried out by using a sintering diamond saw.     

陶瓷/KFRP双板复合构件的孔加工

工程陶瓷和Kevlar纤维增强复合材料(简称KFRP)都是难加工材料,陶瓷/KFRP双板复合构件的孔加工比较困难。在分析双板复合构件组成材料的加工技术现状的基础上,采用专门研制的烧结金刚石钻头对其进行加工试验研究,探讨了其工艺特点,分析了影响加工效率的主要因素。     

陶瓷复合构件的高效钻孔技术研究

针对陶瓷复合构件组成材料的物理机械性能及加工特性,探讨了其加工技术,考虑加工的经济性、实用性和易操作性,采用专门研制的烧结金刚石套钻进行孔加工技术研究,讨论了影响加工效率的主要参数。根据复合构件加工中的各种缺陷,分析了采用预压应力钻削对改善表面加工质量的重要性。以加工效率为指标,通过正交试验对钻头的磨料粒度、浓度、水槽数和壁厚等因素进行了优化分析,确定了适宜的刀具参数。试验证明,采用优化参数的套钻可高效地对陶瓷复合构件进行钻孔加工,质量完全满足技术要求。该套钻同样适合于其他硬脆材料及其复合构件的加工,具有较强的推广应用价值。     

工程陶瓷材料孔加工技术的试验

立足于传统加工方法 ,考虑加工的经济性、实用性和易操作性 ,采用新研制的单层高温钎焊金刚石套料钻及专用钻套夹具对工程陶瓷材料进行了钻孔加工试验 ,试验结果表明 ,该工艺方法可高效、简便地加工出高质量的陶瓷孔 ,具有实用和推广价值。     

陶瓷加工专用套料钻的研制

简要介绍了工程陶瓷材料的性能;选择了加工方式和工具材料;分析了套料加工原理;讨论了金刚石套料钻的结构及制作工艺,给出了套料钻的主要性能参数。     

SiC陶瓷旋转超声振动套磨制孔有限元仿真及实验研究

为解决SiC陶瓷加工时容易出现崩边、裂纹等问题,结合仿真与实验对其进行旋转超声振动套磨制孔技术研究。根据SiC陶瓷宏观力学本构模型,建立SiC陶瓷制孔仿真有限元模型并进行加工过程仿真分析,相比常规制孔,超声振动制孔的仿真轴向力最大可减小26.1%。常规加工和超声振动加工的对比实验研究表明,旋转超声振动加工可减小轴向力达32.9%,可大幅减少陶瓷材料脆性断裂,显著改善孔壁表面质量。有限元仿真与实验研究所得的轴向力在超声振动下最大相差7.5%,常规条件下两者最大相差14%,验证了有限元模型的正确性。仿真和实验研究结果表明：超声振动加工可显著减小轴向力和刀具磨损、提高刀具耐用度、改善制孔质量、降低加工成本。     

陶瓷复合构件的钻削力试验研究

以典型的陶瓷复合构件(陶瓷/玻璃钢/铝合金)为例,通过烧结金刚石套料钻头定压加工试验,深入分析了孔加工过程中的钻削力变化规律。通过正交试验和多元回归分析,建立了综合考虑钻头参数和切削用量的工程陶瓷套孔加工钻削轴向力的经验公式,并分析了各参数对钻削轴向力的影响。研究成果为工程陶瓷及陶瓷复合构件套孔加工时钻头参数和切削用量的优化选择提供了参考依据,对专用机床的开发也具有一定的指导意义。     

钎焊金刚石薄壁钻加工工程陶瓷的试验研究

通过用钎焊金刚石薄壁钻加工Al2O3工程陶瓷的钻削试验,测量和分析了在不同加工参数下钻削轴向力和扭矩的变化,并与电镀钻头的加工性能进行了对比。结果表明,用钎焊金刚石薄壁钻加工工程陶瓷材料的设想可行,与电镀钻头相比,钎焊钻头钻削过程更稳定,加工质量更好,尤其在高转速、大进给加工条件下具有明显优势。     

烧结金刚石套料钻钻削凯芙拉纤维增强复合材料的研究

介绍凯芙拉纤维增强聚合物基复合材料的结构和性能特点,针对复合材料在钻孔加工过程中产生各种加工缺陷的原因,采用烧结金刚石套料钻和专用的工艺装置进行加工试验,分析加工机理,给出合适的工艺参数,为加工该类纤维复合材料提供一条新的途径,具有实用和推广价值。     

方舱用工程陶瓷材料孔加工技术的试验研究

从加工的经济性、实用性和易操作性考虑,立足于传统加工方法,采用了最新研制的单层高温钎焊金刚石套料钻,设计了专用夹具,对工程陶瓷进行了钻孔加工试验。试验结果表明,这种工艺方法可以高效简便地加工出较高质量的陶瓷孔,具有实用和推广价值。     

Investigation on drilling-grinding of CFRP

It is difficult to machine polymer matrix composites reinforced by carbon fibre, and the holemaking process is the most necessary machining process for composite plate products. Conventional drills have a very short life in the drilling of this kind of composites and the quality of the hole is very poor. In this paper, the cemented or plated diamond core tools are tested to make holes in carbon fibre/epoxy composite plates. The effects of machining parameters, cooling and chip removal on the tool life, and the hole quality are investigated. The results indicate that the material removal mechanism of the two kinds of diamond tools is not like the cutting effect of the conventional drilling but similar to that of grinding. Satisfactory effects in making holes in the composites are obtained—quite acceptable machined hole quality, low costs, and long wear-resistant endurance.     

Analysis on profile accuracy for ultrasonic machining of alumina ceramics

Ultrasonic machining (USM) is a mechanical material removal process which has great potential for machining hard and brittle materials such as ceramics, semiconductors, glasses, etc. The accuracy of the job profile generated by USM can be improved by optimal control of the process parameters. This paper presents the study on the influences of ultrasonic machining process parameters such as abrasive grit size, slurry concentration, power rating, tool feed rate and slurry flow rate on generated hexagonal hole profile. The angular deviations at corner angles, dimensional deviations across flat surfaces and dimensional deviation across corners of the hexagonal hole profile have been studied. Based on experimental results, the influences of abrasive grit size, slurry concentration, power rating and tool feed rate were analysed. From the analysis of parametric influences based on various test results, the best parametric combination was found as grit number of 600, slurry concentration of 30 %, power rating of 50 % and feed rate of 1.08 mm/min for achieving better profile accuracy during machining of Al₂O₃ ceramics. The experimental investigations carried out for determining the influence of USM process parameters will provide effective guideline to select parametric settings for achieving desired job profile accuracy on non-circular holes during ultrasonic drilling of alumina.     

特种金刚石钻头的研制

介绍一种新研制的能把超声振动和金刚石磨粒磨削结合在一起的特种金刚石钻头。阐述了该钻头的钻削机理及设计制作过程。试验表明，该钻头是钻削工程陶瓷、宝石等硬脆材料的理想工具。     

一种陶瓷材料磨削加工性的综合评判方法

磨削是目前工程陶瓷的主要加工方法 ,本文以陶瓷材料的物理、力学性能为依据 ,应用模糊数学中的模糊综合评判原理 ,建立了工程陶瓷材料磨削加工性的二级模糊综合评判模型 ,提出了一种对工程陶瓷材料磨削加工性进行综合评判的新方法。选择陶瓷材料的 3个力学性能参数构成因素集合 ,根据提出的评判方法 ,对 4种典型工程陶瓷材料的磨削加工性进行评价 ,并根据综合评价指标进行排序。结果表明 ,该方法的评判结果合理 ,评价方法易于运用计算机来处理 ,简单实用。此方法将工程陶瓷材料的可加工性的评价建立在材料性能参数分析的基础上 ,在磨削加工之前确定材料的磨削加工性。评价结果对工程陶瓷材料的加工过程中工具和工艺参数的确定具有重要指导作用。     

Chipping minimization in drilling ceramic materials with rotary ultrasonic machining

Ultrasonic machining (USM) has been considered as a new cutting technology that does not rely on the conductance of the workpiece. USM presents no heating or electrochemical effects, with low surface damage and small residual stresses on workpiece material, such as glass, ceramics, and others; therefore, it is used to drill microholes in brittle materials. However, this process is very slow and tool wear dependent, so the entire process has low efficiency. Therefore, to increase microhole drilling productivity or hole quality, rotary ultrasonic machining (RUM) is considered as a strong alternative to USM. RUM, which presents ultrasonic axial vibration with tool rotation, is an effective solution for improving cutting speed, precision, tool wear, and other machining responses beyond those of the USM. This study aims to reduce the microchipping or cracking at the exit of the hole, which inevitably occurs when brittle materials are drilled, with consideration of tool wear. To this end, response surface analysis and desirability functions are used for experimental optimization. The experimental results showed that the proposed RUM scheme is suitable for microhole drilling.     

CFRP/TC4叠层材料低频振动钻削试验研究

低频振动辅助切削技术是基于传统切削给刀具加上有规律并可控的振动,从而达到减小切削力、提高加工精度和延长刀具寿命的目的。将低频振动辅助切削技术应用到CFRP/钛合金叠层材料制孔中,在孔径、孔壁粗糙度和入口质量等制孔质量方面与传统钻削进行对比试验研究。结果表明,振动钻削在制孔质量上具有明显的优势。     

An estimation of ballistic limit for ceramic-FRP composite armor

An analytic method is proposed to estimate ballistic limits of ceramic-FRP composite armors. In this method the ballistic limit is evaluated using energy balance approach, that is, the kinetic energy of a projectile just before striking against the armor is assumed to be equal to the sum of energies absorbed during the penetration. The absorbed energies are divided into three parts as follows: the ones absorbed during the penetration into the ceramic facing and the FRP backing, respectively, and the elastic deformation energy of FRP backing. Through comparisons with Wilkins' experimental results this method is shown to be effective to estimate the ballistic limit of composite armors which consist of 4.064mm to 8.635mm thick AD85 ceramic plate and 4.445mm to 9.525mm thick glass FRP plate.     

异质多元多层印制电路板精密孔机械加工

孔是实现印制电路板层间互联及电子元器件装配的核心组成单元,机械钻孔是印制电路板制孔的主要方法。要在印制电路板上进行高密集度孔群的连续可靠、高质量、高一致性和高稳定性加工非常困难,涉及的异质多元多层复合材料机械加工理论复杂,也对加工刀具、加工技术提出了严峻挑战。从机械加工的角度归纳了典型印制电路板分类、组成结构与热力学特性,并提出其机械钻孔加工面临的难点;从材料变形与断裂、钻削热、钻削力与扭矩、孔创成机理、刀具失效机制五个方面,总结了典型印制电路板钻削理论的最新进展,综述了印制电路板用钻头设计、钻孔加工工艺和钻削过程检测技术的研究现状,从印制电路板微孔钻削加工理论、微细刀具优化设计、低温介质辅助钻削加工与孔质量无损检测方面指出了现有研究存在的问题,并结合新一代高端印制电路板发展趋势与孔制造需求,提出了未来印制电路板孔加工研究应重点关注的方向。     

旋转超声加工机理的有限元分析

旋转超声加工是加工玻璃、工程陶瓷和宝石等硬脆材料的有效方法,具有较高的生产率、良好的加工精度和表面质量。在对其加工机理的研究过程中,选用金刚石磨粒和玻璃工件进行建模,运用LS—DYNA软件对工件在加工中的应力变化情况和裂纹的产生与发展进行模拟,结合试验结果,对其加工机理进行研究,并对加工表面质量进行分析。     

变进给量振动钻削提高微小孔加工质量的分析

应用压电陶瓷振动台振动钻削装置,采用变进给量振动钻削法加工微小孔,并用工具显微镜对入钻定位误差和出口毛刺进行测量。采用最小二乘法对所得试验数据进行处理,从而得到进给量与出口毛刺之间的关系,通过对两种条件下(变进给量振动钻削和普通钻削)所得试验数据的比较可知,变进给量振动钻削能使加工质量得到很大提高。