基于旋转超声振动的氧化锆陶瓷小孔磨削加工质量研究

针对陶瓷材料小孔加工质量较差以及加工成本较高等问题,设计一种基于旋转超声辅助的氧化锆陶瓷小孔磨削加工工艺。首先分析旋转超声加工原理,然后在超声振动条件下利用金刚石刀具对氧化锆陶瓷小孔进行单因素磨削加工试验,并对小孔的内壁进行形貌分析和粗糙度检测,最后研究主轴转速、超声功率以及进给速度对小孔表面粗糙度的影响规律。研究结果表明:与普通磨削方式相比,在旋转超声辅助加工条件下,小孔表面质量和残余应力都得到较大改善,当超声功率达到300 W时,加工后的小孔表面粗糙度下降了52%,加工精度明显提高。      

超声辅助电解磨削GH625微小孔工艺研究

超声振动辅助电解磨削加工技术是一种以超声振动作为辅助、电解磨削为主要加工方式实现零件精加工的新型加工技术.为获得更高表面质量的管电极微孔,首先利用单因素法对GH625材料进行管电极打孔,初步得到最小平均锥度0.043°的微小孔,然后通过正交试验研究脉冲电压、电解液浓度、主轴进给速度、阴极转速对加工微小孔锥度和表面质量的...     

电解研磨复合加工技术在孔后处理中的应用

电解研磨复合加工方法是把电解加工和研磨加工结合起来，利用中性电解液通以适当的电流，在磨料研磨和电解溶解共同作用下，对零件进行快速、高效的精密加工。把这一加工技术运用于孔后处理中，对该技术的工艺原理、表面粗糙度的影响因素、加工精度及金刚石磨头的使用寿命等方面进行了研究分析。试验结果表明，该技术能有效去除孔加工后的变质层（如再铸层等），降低表面粗糙度值，降低或消除残余应力，提高表面质量。     

电解研磨扩孔新技术研究

电解研磨扩孔是在吸收电解磨削、电解珩磨和金刚石类磨具研磨等技术优点的基础上开发的一种能浮动定心的高效、低成本的孔后处理加工技术。对该技术的工艺原理、表面粗糙度的影响因素、加工精度及磨具电极的使用寿命等方面进行了研究分析。试验结果和初步应用表明，该技术能有效去除孔加工后的变质层(如再铸层等)，改善表面粗糙度，降低或消除残余应力，提高表面质量。     

Tube electrode high-speed electrochemical discharge drilling using low-conductivity salt solution

Film cooling holes are widely used in the aerospace industry, and their fabrication requires high machining speed and accuracy, as well as good surface quality. Tube electrode high-speed electrochemical discharge drilling (TSECDD) is a promising hybrid machining method for the fabrication of film cooling holes in difficult-to-machine superalloys. An electrochemical reaction can occur if a low-conductivity salt solution is used in the drilling. Materials can also be removed at a high speed using electrical discharge machining (EDM). Thus, TSECDD and electrochemical machining (ECM) can be combined into a unique machining process using a low-conductivity salt solution. This machining process achieves both a high machining speed and good surface finish. In this study, the material removal mechanism of TSECDD was studied using a low-conductivity salt solution, and comparisons with high-speed electrical discharge drilling were made. The performance of the process was investigated using salt solutions of various conductivities. The results show that there are different material removal mechanisms in the frontal gap and the lateral gap and that, in the latter, there is a transition from EDM to ECM. Experiments conducted using TSECDD confirm that the use of this process with a low-conductivity salt solution can improve the machining surface and machining efficiency achieved. The results also show that the use of a low-conductivity solution improves the material removal rate, the hole diameter, and the taper angle.     

型孔电解加工阴极优化试验研究

为解决电解加工型孔的加工稳定性和形状精度等问题,建立了异形孔电解加工稳定过程中加工间隙数学模型,分析了工具阴极结构对加工区域和非加工区域的电场及其均匀性以及其对电流密度与加工效果的影响,通过优化工件结构改善了加工间隙内的电场分布,使工件形状精度显著提高,并进行相关试验对仿真结果进行验证。得出结论:在相同的电解加工参数下,工具电极的结构对工件的形状精度有着显著的影响,通过优化工具电极结构,改善加工间隙内的电场分布与电流密度,让加工间隙内的流场更为稳定,使工件侧壁垂直度提高,提高了电解加工的形状精度与加工稳定性。     

Electrochemical deburring system using electroplated CBN wheels

Deburring and edge finishing technology as the final process of machining operation is required for manufacturing of advanced precise components. Fitting a deburring process into FMS (flexible manufacturing system) with high efficiency and full automation is a difficult problem. There is no standardized procedure for the removal of burrs of various shapes, dimensions and properties and currently manual methods are used. In particular, deburring of internal cross holes which are perpendicular to a main hole is more difficult and the electrochemical method is a potential solution. Therefore, it is needed to develop the electrochemical deburring technology for internal deburring in a cross hole shape.In this study, the mechanism of electrochemical deburring by using electroplated cubic boron nitride (CBN) wheels is described and its deburring performance is investigated in an internal cross hole. Also, deburring efficiency for internal cross holes is examined with electrolytic currents and other electrochemical conditions. The optimum range of deburring the internal cross hole corresponding to the acquired edge quality is determined.     

磨削对氧化膜去除质量影响的稳定性与敏感性

目的研究磨削参数对电化学加工氧化膜去除质量的影响规律,以及各参数对氧化膜去除质量影响的稳定性和敏感性。方法在试件表面形成均匀一致,无缺陷电化学加工氧化膜的前提下,借助自主搭建的机械磨削实验平台,分别研究磨粒尺寸、工件速度、磨削压强和加工时间对氧化膜去除质量的影响,使用精密电子天平和扫描电子显微镜对实验前后的试件进行测量,结合稳定性与敏感性分析理论对实验结果进行分析。结果不同的加工参数对氧化膜去除程度的影响不尽相同,氧化膜既存在不完全去除的现象,也存在完全去除的现象。扫描电子显微镜结果也显示,不同尺寸的磨粒对氧化膜的破坏程度不同,其表面氧化膜的沟槽深浅不同。结论受氧化膜硬度低、容易去除和基体金属硬度高、不容易去除的影响,氧化膜去除质量随着工件速度和加工时间的增加呈现三次曲线的规律增加,随磨削压强和磨粒尺寸的增大呈线性增加趋势。磨削参数对氧化膜去除质量影响的稳定性与敏感性不同,而且在电化学机械加工生产应用中不改变磨削工具,所以在磨削参数相对值较低的区间,其对去除质量影响的稳定性由大到小(敏感性由小到大)为:磨粒尺寸、加工时间、磨削压强、工件速度。在磨削参数相对值较高的区间,稳定性由大到小(敏感性由小到大)为:磨粒尺寸、磨削压强、工件速度、加工时间。加工中优先选择稳定性高(敏感性低)的参数作为调整电化学机械加工效果的主要因素,可在提升经济性的同时,提高加工精度。     

20CrMnTi高速外圆磨削试验研究及参数优化

为改善20Cr Mn Ti渗碳合金钢的表面磨削效果,对20Cr Mn Ti合金钢进行了高速外圆磨削试验,分析了磨削工艺参数对表面粗糙度的影响规律。基于高速磨削试验,利用最小二乘多元线性回归方法,推导并求解出了20Cr Mn Ti合金钢的磨削粗糙度预测模型。利用最优化设计方法和MATLAB优化工具箱,以加工效率为目标函数和以粗糙度预测模型为约束条件,针对企业实际的磨削问题优选了工艺参数。优化的工艺参数在保证表面加工质量的基础上可提高加工效率,这为加工企业降低生产成本提供了重要的理论依据和案例参考。     

MA956高温合金活动模板电解加工小孔技术研究

对采用活动模板电解加工技术在MA956铁基高温合金薄板上加工小孔的工艺方法进行了讨论。研究了电解液温度、加工电压、电源占空比和脉冲频率等参数对小孔加工结果的影响。研究表明:采用10%w.t.NaNO_3电解液,在电解液温度为30℃、加工电压为40 V、电源占空比为30%、电源脉冲频率为400 Hz时,能在MA956高温合金薄板上加工获得锥度小的小孔。     

Precision shaping of small diameter wheels using micro electric discharge truing (MEDT) and hole-machining of Al2O3 material

There still exist many problems and difficulties in the precision hole-machining of advanced ceramics, composite materials, ultra hard alloys, reinforced plastics, etc., especially, for very small diameter holes. The process is usually unstable, and its efficiency is very low. In this paper, a new method is put forward, to fabricate and prepare a small sintered grinding wheel for the grinding of small holes. This method is a combination of sintering and on-machine non-contact truing. It can shape wheels to various forms, and to a very small diameter. In addition, a novel on-machine micro electric discharge truing technique has been proposed, its truing efficiency and some other process phenomena have also been analyzed in detail. The system configuration is simple, however it can be used to true and dress grinding wheels of very fine abrasives and small diameters. The real mechanism of the novel truing method with AFG-M as the working agent is first elucidated as a compound process, in which electrolytic action, electric erosion, and electric discharge removal of the oxide layer are incorporated together. Finally, through hole machining tests of Al₂O₃ ceramics, the difficulty of small hole machining has been identified, and the prerequisites of stable process have been given. The results of comparison test of two kinds of wheels show the effectiveness of proper wheel shape.     

Combination of capacitance and conductive working fluid to speed up the fabrication of a narrow, deep hole in electrical discharge machining using a dielectric-encased wire electrode

An attempt was made to increase the machining speed of a new electrical discharge machining system for fabricating narrow, deep holes in metal. The method employs a wire encased in a dielectric jacket as the tool electrode, in contrast with the conventional pipe electrode. The role of the dielectric jacket is to completely suppress unnecessary secondary discharges occurring between the sidewalls of the wire and the fabricated hole. In the present study, the effectiveness of the combination of conductive working fluid and a capacitor connected to the work piece and the tool electrode was examined. Although electrode wear was severe, machining speed with this combination (saline water at 150–250 μS/cm and capacitance at 8 μF) was twice as fast compared with fabricating a hole ( 0.8–0.9 mm) without a capacitor and saline water in a 20-mm thick carbon steel block. The mechanisms involved are discussed based on electrical circuit theory and electrochemical corrosion.     

MQ6820插齿刀刃磨机床的设计

介绍了插齿刀加工过程中表面磨损的特点,分析了插齿刀刃磨机设计的必要性和可能性,提出了大直径插齿刀刃磨机床的设计方案,并确定了砂轮直径及磨削用量。实际运行情况表明,该插齿刀刃磨机床刃磨质量和效率能够满足生产要求。     

Micro hole machining by conventional penetration electrical discharge machine

This work aims to study the parameters that affect the micro hole machining process (diameter smaller than 0.1 mm and thickness/diameter relation bigger than 20), by electro-erosion penetration process in sheets. To make the execution of the micro holes in conventional machines possible, the construction of two devices is proposed, a mechanical and an optical one. From results experimentally obtained, the process proved to be technically and economically viable, mainly if compared with mechanic drilling, as it presents advantages when cost per tool, number of holes per tool, drilling length, and precision of the holed dimension are considered. The circularity deviation provided by the experiment was smaller than 0.01 for 0.1 mm diameter holes made in 2.4 mm thick SAE 1010 steel sheets. It was also concluded that the quality of the hole directly depends on the cleaning process.     

挤压油膜阻尼器在深孔磨削中的应用研究

基于挤压油膜阻尼理论，设计了带挤压油膜阻尼器（SFD）的深孔内圆磨削刀杆，并在高精度内圆磨床上进行了与静压支撑刀杆的磨削性能对比实验，实验表明，参数设计合理的SFD开杆较静压支撑刀杆具有更优良的磨削性能和减振效果，而且SFD刀杆较静压支撑刀杆结构简单，拆装方便，稳定性高，因此SFD在机械加工领域具有十分重要的研究价值和广泛的应用前景。     

Speed Stroke Grinding of γ-Titanium Aluminides

This paper describes the developments to implement the innovative technology of speed stroke grinding for machining γ-titanium aluminides. These are difficult to cut materials with high application potential in the aeronautics industry. In a first step, a holistic process model is developed, which considers the tool wear and the mechanical and thermal energy balances at high table speeds as well as the crack formation mechanisms. In a second step, the theoretical process model of speed stroke grinding is verified and extended by experimental investigations. In addition to the analysis of the tool wear mechanisms crucial points of the grinding investigations are the analysis of the grinding temperatures and the structure of the workpiece surfaces with special regard to crack and residual stress formation.     

Wear reduction at double face grinding with planetary kinematics

To machine high performance materials efficient and process safe, innovative tool concepts are required. Double face grinding with planetary kinematics is a process, which can be used to machine workpieces with high demands on flatness. Especially the kinematic of this process leads to an unequal wear shaping, which has a negative effect on the quality of the workpieces. Fulfilling the sophisticated task of ceramic machining, it is necessary to consider the chip formation and the associated wear of grinding tool based on existing approaches under consideration of the radius dependent speed gradient and significantly increased grinding wheel speeds as well. The research is the basis for the development of a tool, which allows predicting wear on the tool for double face grinding with planetary kinematics. Based on the knowledge about the wear, it is possible to design tools with requirements and customized for special processing task.     

金刚石钻磨头超声振动钻磨硬脆材料表面质量的试验研究

硬脆材料以其优良的性能在生产实践中得到了广泛应用，但其低塑性、易脆性及不导电性等使得加工十分困难，尤其是超精密表面制作更加困难。为此，本文将超声振动引入普通钻磨中，介绍了超声振动切削原理，通过超声与普通两种方式下的表面粗糙度试验和微观形貌观察得出以下结沦：1）不同加工参数时，超声振动钻磨时的工件表面粗糙度值均低于普通钻磨时的表面粗糙度值；2）随着进给量、工件转速和输入功率的增加，超声和普通钻磨时的表面粗糙度均呈上升趋势；3）普通钻磨加工后孔壁表面有宽度和间距不均匀的沟槽，并且沟槽较宽，而超声钻磨加工后表面沟槽（划痕）较浅且均匀。     

小直径磨棒磨削加工TiC颗粒增强钢基复合材料GT35

为探究TiC颗粒增强钢基复合材料GT35合理的加工参数和冷却润滑条件,研究其对切削力、表面质量及刀具磨损的影响规律,采用小直径磨棒以侧面磨削方式开展试验。结果表明：干磨削会引起磨棒烧伤,极压磨削油的润滑效果优于水基合成磨削液的;磨棒在极压磨削油润滑下,磨削工件12 min后进入稳定磨损状态,其主要磨损形式为磨粒破碎、磨粒磨耗和磨粒脱落;主轴转速对切削力的影响大于进给速度的,且转速越高,切削力越小;工件表面粗糙度主要与磨棒磨粒出露高度的平整度有关,受加工参数的影响较小。用小直径磨棒磨削加工GT35材料时,应选择极压磨削油润滑,高主轴转速、中速进给的加工方式,以获得良好的刀具寿命、工件加工表面质量及适当的加工效率。     

复合进给对锥形孔电解加工过程的影响

为提高锥形孔加工精度,采用圆锥阴极复合进给的电解加工工艺方案,首先分析了阴极复合进给对加工间隙流场的影响,从促进加工间隙电解产物的排出及优化间隙流场的角度证明了复合进给能有效提高电解加工精度。基于自主研制的复合进给电解加工装置系统进行了工艺试验,研究了复合进给参数对锥形孔孔径及锥度的影响。最后,采用优选的工艺参数加工出的锥形孔能满足现有喷油嘴锥形孔的加工要求,且加工过程稳定。