A Study of the Mirror-Like Grinding of Sintered Carbide with Optimum In-Process Electrolytic Dressing

Sintered carbide is widely used as the material for tools and die moulds, but it is difficult to grind because of its brittleness and hardness. A superabrasive diamond wheel is required for mirror-like grinding of this material. The completion of in-process dressing of a superabrasive wheel makes possible effective precision grinding of sintered carbide. This study proposes a new in-process electrolytic dressing system for this purpose. Using optimum in-process electrolytic dressing, the surface roughness is improved and the grinding force is very low. Optimum in-process electrolytic dressing has proved to be a good method for obtaining efficiency and mirror-like grinding of sintered carbide.     

A Study of the Development of an Ultraprecision Grinding System for Mirror-Like Grinding

In this study, a new system of optimum in-process electrolytic dressing and a microposition system are developed. This system can carry out optimum in-process dressing of superabrasive wheels, and gives effective control of the unstable dressing current and insulating layer. Therefore, ultraprecision grinding when using an optimum in-process electrolytic dressing system and microposition system is a good method for efficient mirror-like grinding of brittle materials.     

硬质合金ELID镜面磨削的试验研究

硬质合金具有硬度高、强度好、耐腐蚀和耐磨损的特点,采用传统方法难以满足精密及超精密加工的技术要求,而且工序多、效率低、成本高。本文采用在线电解修整（ELID）技术对硬质合金进行精密镜面加工。通过试验,分析了磨削深度、电极间隙、占空比、电解电压对硬质合金表面粗糙度的影响规律,并得到了优化的EI。ID磨削工艺参数。使用优化后的ELID磨削工艺参数加工硬质合金材料可获得较低的表面粗糙度。     

ELID镜面磨削砂轮氧化膜生成机理

采用铸铁结合剂微细超硬磨料砂轮进行在线电解修整磨削时,ＥＬＩＤ砂轮表面产生的氧化膜起着极其重要的作用。研究了ＥＬＩＤ砂轮电解氧化膜的粘附强度、硬度、致密性、导电性、生成速度与砂轮结合剂成分、磨削液成分和电解参数的关系。     

The Effect of Optimum In-Process Electrolytic Dressing in the Ultraprecision Grinding of Die Steel by a Superabrasive Wheel

In recent years, grinding techniques for precision machining of brittle materials used in dies, moulds and optical parts have been improved by using superabrasive wheels and precision grinding machines. Optimum dressing using a superabrasive wheel makes possible the effective ultraprecision grinding of die steel (STD-11). In this study, a new system and the grinding mechanism for optimum in-process electrolytic dressing are proposed. This method can carry out optimum in-process electrolytic dressing of a superabrasive wheel. Optimum in-process electrolytic dressing is a good method for obtaining efficiency and ultraprecision grinding of STD-11.     

微晶玻璃超精密磨削技术研究

分析实现微晶玻璃超精密磨削的技术条件和在线电解修整超精密磨削机理,并采用铸铁基金刚石砂轮结合在线电解的磨削方法对微晶玻璃进行了精密磨削,获得Ｒａ为２．３０８ｎｍ的超光滑表面。     

Grinding of aluminium silicon carbide metal matrix composite materials by electrolytic in-process dressing grinding

The grinding cost of metal matrix composite materials is more due to low removal rates and high rates of wear of super abrasive wheels. This electrolytic in-process dressing (ELID) technique uses a metal-bonded grinding wheel that is electrolytically dressed during the grinding process for abrasives that protrude continuously from super abrasive wheels. This research carries out ELID grinding using various current duty ratios and conventional grinding of 10% SiC_p reinforced 2,124 aluminium composite materials. Normal forces and tangential forces are monitored. Surface roughness of the ground surface, Vickers hardness numbers and metal removal rate (MRR) are measured. The results show that the cutting forces in the ELID grinding are unstable throughout the grinding process due to the breakage of an insulating layer formed on the surface of grinding wheel and are less than conventional grinding forces. A smoother surface can be obtained at high current duty ratio in ELID grinding. The micro-hardness is reduced at high current duty ratio. In ELID, the MRR increases at high current duty ratio. The results of this investigation are presented in this paper.     

A piezoelectric-drive table and its application to micro-grinding of ceramic materials

A micro-positioning table with a 0.005 μm resolution has been developed to enhance the performance of a conventional grinding machine in the fine grinding of ceramics. A piezoelectric actuator with high stiffness and resolution has been applied to drive the table and to provide small depths of cut for the workpiece. The performance of the table is investigated with both open and closed-loop operation to drive the actuator. The accuracy and stiffness of the positioning are improved by means of the closed-loop control. Grinding experiments with ceramics, such as partially stabilized zirconia (PSZ) and hot-pressed silicon nitride (Si₃N₄), were carried out to demonstrate the performance of the table. The actual resolution of depth-of-cut control was determined by measuring ground groove depths on the ceramic surface. A mirror-like surface on the ceramic was easily obtained by grinding at the small depth of cut of 0.1 μm with the aid of the table.     

超精密平面磨床关键技术的发展

随着硬脆材料应用领域的扩大以及砂轮电解在线修整技术的发展,超精密磨削技术在近年来得到了飞速发展,其中超精密平面磨削技术的应用最为广泛。本文介绍了国内外超精密平面磨床的关键技术,包括总体结构、砂轮主轴及驱动系统、导轨及驱动系统、温度及热变形控制等。     

Precision Grinding of Mn-Zn Ferrite with In-Process Electro-Discharge Dressing

Ferrite is widely used as a material for magnetic heads for hard disks, but it is difficult to grind because its high hardness and brittleness. Therefore, a superabrasive diamond wheel is used for precision surface grinding of this material. However, the conventional dressing method cannot be applied to a superabrasive diamond wheel. This study describes a new method for carrying out effective in-process electro-discharge dressing (IEDD) of a superabrasive diamond wheel. Using IEDD, the surface roughness of the Mn-Zn ferrite was improved, and the grinding force was reduced. IEDD is a good method for obtaining efficient surface grinding of ferrite.     

钢结硬质合金的精密镜面磨削技术的研究

入引了一种在线电解修整金属基超硬磨料砂办密镜面磨削新地钢结硬质合金进行了精密面磨削,得到了粗糙度为０．００３μｍ～０．０１１μｍ的镜面,一次磨削成形。效率高,可取代目前的多级研磨工艺。     

Experimental study of wheel wear in electrolytic in-process dressing and grinding

Profile accuracy of components ground with ultra-precision machine tools is primarily dependent on wheel wear. Quantitative analysis of wheel wear is therefore an important aspect for precision grinding with electrolytic in-process dressing (ELID). In this paper, wheel wear is measured from ELID grinding experiments with different dressing and machining parameters. The grinding forces and dressing current characteristics of the experiments are also compared. Based on the results, a benchmark function is defined for wheel wear rate. A relation for identifying insufficient dressing from sufficient dressing for particular machining conditions is also identified. It is found that insufficient dressing produces pitting and/or arcing on the wheel surface, and wheel wear can be linearly correlated to ELID grinding conditions when the wheels are sufficiently dressed.     

The effects of dynamic characteristics on the surface texture in mirror grinding

In order to make clear the effects of mirror grinding conditions on the ground surfaces in the surface mirror grinding of sintered carbide adopting an in-process electrolytic dressing method, experiments are conducted to measure the vibration signals of the workpiece during grinding and the profile of the ground surface. It is found that components with low frequency vibration signals have a very close relation to the undulation of a ground surface and components with high frequencies to the surface roughness .     

超精密平磨总体设计及关键件加工工艺的研究

介绍ＣＪＭ－１型龙门式超精密平面磨床的总体方案及指标的设计、若干关键部件如主轴、导轨等的加工工艺。     

Precision grinding of bearing steel based on active control of oxide layer state with electrolytic interval dressing

The oxide layer state directly relates to machining quality in electrolytic in-process dressing (ELID) grinding. In this paper, intermittent grinding control strategy was used to monitor and control the state of the oxide layer in interval ELID (ELID II) grinding. Some experiments were implemented based on active control of the oxide layer state. The influence of dressing current, wheel speeds, and grit size on surface roughness and waviness has been discussed in detail with ELID II grinding for bearing steel. The experimental results illustrate that the ELID II method can realize a stable grinding process based on active control of the oxide layer state. The surface roughness (Ra) and waviness (Wa) increase with increase of the dressing current. When the dressing current is constant, Ra and Wa reduce as wheel speed increases and decrease as grain size of wheel decreases. The experimental results also show that sufficient abrasive protrusion can be ensured in ELID II grinding, especially for grinding with a W2.5 super-abrasive wheel which may produce a very smooth surface quality, Ra 0.0166 μm and Wa 0.018 μm.     

Evaluation of surface characteristics of ground CVD-SiC using cast iron bond diamond wheels

The precision and efficient machining of CVD-SiC ceramic to required quality has not been well established yet. In this paper, a comparative study was conducted to investigate the special aspects in grinding of CVD-SiC ceramic, with ELID method or rotary dressing method. The stability of surface roughness, effects of material properties and dressing methods on grinding results, effects of material properties and dressing methods on surface stress state, and microscopic analysis of ground CVD ceramics by both methods were well analyzed. In addition, a wheel-workpiece interaction model was proposed for the two dressing methods.     

A future technology for silicon wafer processing for ULSI

Two types of current surface grinder methods used in the preparation of silicon wafers are compared (creep-fed and in-fed). The creep-fed method left deeper residual damage in the waters as compared to the in-fed method. Second- and third-generation grinder developments, also discussed, indicate the possible directions for future production processes. For the second generation, electrolytic dressing was used to achieve stable grinding with the very rigid metal-bond with fine diamond. The maximum damage depth obtained was about 1 μm. In the third generation, plastic-regime grinding was used. A method of stripping silicon layers analogous to wood shaving is proposed. With this technology, it is expected that the damage depth would be about 0.2–0.3 μm and the accuracy of surface flatness to be ± 0.01 μm. It is expected that even with this accuracy, high productivity grinders for larger diameter wafers ( 200 mm) will be available in the near future.     

激光与电火花复合修整粗粒度弧形金刚石砂轮试验研究

因受到激光高斯光束特性的影响,辐照在砂轮表面上的光斑大小和激光能量都跟随修整路径变化,难以实现高精度的弧形金刚石砂轮的修整,为此,提出采用激光粗修整和电火花精修整的复合修整方法。先用激光修整高效去除多余磨料层来得到弧形轮廓,再用一高精度弧形电极匹配该轮廓进行电火花修整,得到较高精度的弧形砂轮。在粒度为120的金刚石砂轮上试验修整半径为13 mm的弧形轮廓,最终修整出的弧形轮廓半径为13.006 mm,轮廓误差PV值为10.90 μm。最后,通过磨削氧化铝陶瓷验证了砂轮修整效果。检测磨削工件的弧形轮廓拟合半径为13.012 mm,轮廓误差PV值为11.33 μm。     

Development and Analysis of Foil Electrodes for High Speed Electrolytic In-Process Wheel Dressing

This paper discusses the development of an effective electrolytic in-process dressing technique for high speed grinding. An innovative foil electrode has been designed and tested. The performance of a hydrodynamic foil electrode is discussed. Experimental investigations confirm that foil electrodes show significant improvement on electrolytic in-process dressing even when the electrolyte supply rate is low.     

结合在线电解修锐高效磨削陶瓷密封件研究

本文通过设计制作金属结合剂金刚石磨具，结合电解修锐技术对Al2O3陶瓷密封进行了研磨式磨削实验在实验过程中通过检测磨具表面的磨粒出露高度及陶瓷材料的去除量，评价该磨削工艺在陶瓷材料密封件加工中的应用效果。结果表明，电解修锐可有效地修锐金属结合剂金刚石磨具，在加工过程中使磨具保持良好的切削能力，因此材料去除量较大，加大工时短，陶瓷密封件的加工成本得到控制。