Key Engineering Materials Vols. 389-390

Abstract: This study aims to develop an ultrasonically assisted grinding technology for precision internal grinding of a small hole measuring several millimeters in diameter, such as those formed in a fuel injector for an automotive engine. In a previous work, an experimental apparatus mainly composed of an ultrasonic vibration spindle was designed and constructed, and grinding experiments were carried out. The purpose of this paper is to examine the effect of ultrasonic vibration on grinding force and surface roughness when the grain size and concentration of small cBN grinding wheel are changed. The experimental results indicate that applying ultrasonic vibration to the wheel decreases the normal and tangential grinding forces by more than 50% and 78%, respectively, and improves the surface roughness by as much as 10% when the wheel grain size and concentration are changed. In addition, over the range of grinding conditions employed in this paper, the grain size as small as 5μm can be used in ultrasonically assisted grinding.

Abstract: In order to realize electrochemical finishing in tap water, an ultrasonic vibration using a transducer enabling three kinds of vibration modes, i.e., axial, bending, and complex, was given to the electrode. During the test finishing, it was observed that with electrode without ultrasonic vibration, the workpiece surface was simply covered with the rust. On the contrary, by applying the ultrasonic vibration of bending vibration mode or complex vibration mode with an appropriate amplitude, the material removal rate was increased and the surface roughness was improved.

Abstract: The current study using ultrasonic energy transmitted into the electrolyte to assist in discharging of electrolytic product and cuttings out of the machining gap in the synchronous finish processes of grinding and electrochemical finishing on hole-wall surface beyond traditional process of holes machining instead of conventional hand or machine polishing. The design finish-tool includes a grinding-tool and an electrode as a hole-wall surface finish improvement that goes beyond traditional rough boring. In the experiment, the finish-tool is completely inserted to the hole; the electrode is used with continuous or pulsed direct current. The electrode form and the machining process are obviously different from electrochemical grinding (ECG). The experimental results show that the large supply of current density is effectively to reach the amount of the material removal and is advantageous to the finish processes. The finish effect is better with a high rotational speed of the finish-tool because the dregs and cuttings discharge of electrochemical finishing and grinding becomes easier and is also advantageous to the finish. The average effect of the ultrasonics is more better than the pulsed current while the machining time needs not to be prolonged by the off-time. The synchronous processes of grinding and ultrasonic electrochemical finishing just require a short time to make the hole-wall surface smooth and bright.

Abstract: A prototype three-dimensional tool oscillation system for finishing metal molds, which can oscillate a tool in a figure-8 motion, has been developed. When such a tool motion is used, the lapping direction alternatively changes and consequently a very smooth surface might be achieved in a relatively short time in the presence of a very fine abrasive compound. The developed tool oscillation system consists of three multilayer piezoelectric transducers. The orientation of the tool motion can be changed in three dimensional space. This paper describes the structure of the tool oscillation system, the driving method of the three piezoelectric transducers for oscillating a tool in a figure-8 motion and the measurement results for the tool motions.

Abstract: There are few water-based fluids, on the market, designed specifically for grinding and abrasive machining processes. Fluid manufacturers, caught up in serving the “non-cutting” functions, have neglected the prime reasons for using a grinding fluid. This paper begins to assess water-based fluid chemistries and observe the cause and effect relationship with respect to grinding power and wheel life. The end result will be not only be a next generation grinding fluid, but also a better understanding of the role of the grinding fluid in a grinding or abrasive machining operation.

Abstract: Grinding tests and trials on production equipment is a most expensive proposition. The expense is not only with respect to the monetary cost, but also the down time associated with interrupting a production line to make special runs and set-ups. That high cost is generally the reason given why not to conduct production grinding tests. Testing is more easily justified in a laboratory environment, however the testing can become “clinical” such that it is far removed from the real world of production grinding and the results are often unrealistic. It has been the object of this project to target an industry and simulate, as closely as possible, a production grinding environment, in the laboratory, to encompass all of the realism of bearing production but with quick-changeover features that allow frequent and accurate adjustments to the process with respect to the set-up but moreover, the grinding fluid. The end result is test data that is meaningful, directly relevant, acceptable and understandable to the industry. It has also provided a platform for further investigative work with respect to the surface texture produced by certain fluid chemistries.

Abstract: With the correlation in stochastic process applied to the experimental results, the surface during grinding and further lapping with abrasive jet finishing (AJF) restricted by grinding wheel was investigated with respect to auto correlation function (ACF) , cross correlation function (CCF) and power spectral density (PSD) analysis. The results indicated that AJF made the surface contour formed periodicity in a small range and removed fluctuation of the surface contour in low frequency greatly. The average spacing of the surface contour decreased and the machined surfaces changed from continuous parallel micro-groove and plough to randomly distributed discontinuous micro-pit with the increase of machining circles. The surface texture became fine and surface roughness was obviously improved. Furthermore, the isotropy surface and uniformity veins both parallel and perpendicular machining direction was attained by the finishing process to improve greatly the wearable capability of the workpiece.

Abstract: In order to apply the floating nozzle method to an angular grinding on the external cylindrical grinding, basic experiments on V-groove grinding with the wheel edge were performed on the surface-grinding machine. The results showed that the floating nozzle method could maintain a good control of the wheel edge wear, leading to improved surface roughness compared with a conventional nozzle.

Abstract: Adopting the method of PIV, systematical theory analysis and experiment research were made on the airflow field distribution of super-high speed pectination grinding wheel, as well as experiment design and data acquisition, the data processing was carried out through the software of FlowMap, Tecplot, and Matlab. By analysis and discussion focused on experiment results, the general rules of airflow field distribution in super-high speed pectination grinding wheel were preliminary drawn, which provides the research foundation with a view to find a new method for the effective supply of super-high speed grinding coolant.

Abstract: An actively cooled and activated cooling approach is proposed and examined in this project in order to deal with the problems associated with methods such as the cryogenic cooling method. It is also aimed to further improve the surface quality of the workpiece after grinding by combining the advantages of the existing cooling methods. Both computational and experimental studies were conducted for grinding the brittle materials with the proposed approach. Optical examinations were used to study the surface morphology. The experimental results show that the surface quality can be improved by up to 23.75% on average in terms of surface roughness Ra. The computational test reveals that the heat can be taken away more effectively by the proposed approach.