Xun Lv

An Investigation to Semi-Fixed Abrasives Plate Characteristics

The most typical example of hard and brittle material is advanced ceramics, for its ultra-precision machining difficulty and wide applications, now it becomes a focus of attention. Semi-fixed abrasive plate (SFAP) is newly developed for preventing larger particles from doing workpiece surface damage in machining advanced ceramics, for larger particles from grain size dispersion or from outside of processing area could bring uneven load distribution on processing region of advanced ceramics. In this paper, Shearing strength, surface hardness and Young’s modulus as characteristics of SFAP are investigated. They were influenced by Grain size and abrasive weight ratio are analyzed and discussed, as well as the qualitative estimation of these influences on the characteristics of SFAP are deduced.

Experimental Study on New Bonding Materials for Developing Nano-Grinding Plates

This paper describes a method for experimental development of a novel fixed abrasive nano-grinding plate (FAG-plate) which is proposed for lapping some rigid brittle materials, such as quartz crystal and silicon. The FAG plate is developed with ultraviolet-cured resin by rapid prototyping technology. The analysis shows that such FAG-plate can keep its grinding ability constant and continuous and it can make the roughness of machined surface reach to nanometer level. Based on experimental comparisons with conventional free abrasive slurry lapping plates, the lapping process using FAG-plate has several distinct advantages. One is that the machining efficiency is significantly improved. The second is that it improves the surface roughness of machined work-pieces, although it decreases the flatness tolerance of materials. Furthermore, the fixed abrasive nano-grinding plate is made by the new bonding materials- ultraviolet curing resin and thus the fabrication of FAG-plate is convenient and economical.

An Approach to the Influence of Flotative Abrasive Balls on Polishing Process

Polishing with Flotative Abrasive Balls(FABs) is a kind of soft contact polishing means， and the conventional polishing plate and pad are not needed in this case. The pressure of polishing is the flotage which is the upward force that a fluid exerts on the FABs, but the movement of work piece is similar to that in conventional polishing, the removal rate and quality of polishing is influenced by FAB and its flotage. An experiment device is built up and two kinds of FAB are designed and produced. Some primary experiments are carried out in order to investigate the influences of the size of FABs on the removal rate and surface roughness in polishing with FABs. It is found from the experiments that the grain size and the layers of FAB may have great influence on the removal rate of polishing; the surface roughness is mainly decided by the ball diameter and the layers of FAB. The results of experiments are discussed and analyzed, it indicates that the efficiency and quality depend on flotage and the number of active grains when the velocity of workpiece is assigned.

Study on Ultra-Precise Machining of CLBO Crystal

Cesium Lithium Borate (CsLiB6O10 or CLBO) is the most effective non-linear crystal which generates ultraviolet harmonics of the Nd:YAG fundamental laser wavelength. In order to enhance the damage threshold, low CLBO surface roughness, by ultra-precision machining, is needed. Because the CLBO crystal has easy hydroscopic reaction and micro scratches in machining, ultra-precise machining of the CLBO crystal is a difficult technical problem. In this paper, the new lapping slurry and polishing slurry are introduced. And the deliquescence degree of CLBO is fallen to lowest. A new working technology is also adopted. After rough polishing, the concentration of ultra-precision polishing slurry is increased properly. So does the ultra-precision polishing speed, and the wiping speed is faster than the deliquescence speed. The CLBO crystal surface roughness can achieve 1nm and keep the surface quality well.

Analyze and Verify Cutting Depth Distribution of Different Grits Size SFAP

Semi-fixed abrasive plate (SFAP) lapping is an effective ultra-precision lapping method. It can efficiently obtain good surface quality in ductile regime machining. Probability density function of abrasive grains cutting depth is the key factor to control removing mode. This paper verified the function by analyzing and comparing simulation results and detection results. It showed the simulation results were consistent with the detection results. The more fine grits SFAP could result in the more consistent cutting depth on workpiece surface, and standard deviation of cutting depth distribution of 4000# SFAP was only 0.0754, compared with 1000# SFAP (0.1527).

Numerical Fitting of Processing Load and Downward Movement of Semi-Fixed Abrasive Plate

Semi-fixed abrasive plate (SFAP) lapping is an effective ultra-precision lapping method. It can efficiently obtain good surface quality in ductile regime machining. Probability density function of abrasive grains cutting depth is the key factor to control removing mode. This paper focused on the relationship between processing load and downward movement of the workpiece, which was important equation in probability density formula of abrasive grains cutting depth. By using loading test on pressure tester and numerical fitting method, the relationship can be expressed by different order polynomial formula, and the fitting curves were very close to experimental data.

Numerical Prediction of Manufacturing Error in Sliding Panel Structure

The present work focuses on the numerical prediction of the manufacture quality of a sliding panel structure, in which the mobile components are floating on the immobile components and the 0.002mm thickness oil-film clearance between the mobile and immobile components. The interaction between them is the interfacial coupling interaction. A single-point spring-damping supporting element is introduced to simulate this type of interaction traditionally, in which the torsion of the mobile components is increasing with the supporting element reduced. To analogy the interfacial coupling interaction, the finite centrality supporting method is introduced to study the thin oil-film effect between the mobile and immobile components. And the manufacturing quality is predicting through the numerical study. Compared with the results derived from the numerical and experiments, the manufacturing error is in accordance with each other.

Theoretical Research and Verification on the Porosity of Semi-Fixed Abrasive Tool

Semi-fixed abrasive tool is a new developed grinding wheel which can adjust abrasive grain near the workpiece-abrasive interface according to the situation of the hard and large grits, damaged surface layer generated by the scratch or crack could be decreased when using semi-fixed wheel. Porosity, one of the most important parameters to evaluate trap effect, was studied based on the analysis of uniform scratch and it’s effect on the polishing time, contact models between circle abrasive grain, line boundary and circle boundary were deduced to investigate the relations between engagement depth and the ratio of normal force to normal elastic stiffness. Theoretical research results show that semi-fixed grinding wheel should be conditioned after it’s compaction for the boundary between abrasive grain and line boundary is unstable, the contact status is stable for internal abrasive grain, predicted porosity value agree well with that measured in the experiment, the shear strength of semi-fixed abrasive tool can meet the demand of lapping and polishing processes.

Comparison of Processing Features between Semi Bonded Abrasive Lapping and Loose Abrasive Lapping

Semi bonded abrasive lapping is an effective ultra-precision lapping method. It can obtain good surface quality of workpiece in short time. This paper focused on the differences of processing features by comparing semi bonded abrasive lapping and loose abrasive lapping in several groups processing parameters. The results showed that the surface roughness of workpiece in semi bonded abrasive lapping was far superior to that of loose abrasive lapping in same processing parameters. And the MRR (material removal rate) of semi bonded abrasive lapping was slightly lower than that of loose abrasive lapping. For these features of semi bonded abrasive, a new processing flow would also be proposed in this paper.

Motion Analysis of Ball Grinder with Dual-Rotating Plates Lapping Mode

Dual-rotating plates lapping method is a new type of ball machining technology, in which the spin axis angle of the ball could wiggle up to 180°. An investigation was made to verify the motion model of the dual-rotating plates lapping. The ball motion parameters, such as revolution speed, spin speed and spin axis angle were detected experimentally. The results show that the calculated values and the measured ones of the ball motion parameters are almost identical. The motion model of the dual-rotating plates lapping method is thus verified valid.