Abstract: The profile accuracy of the workpiece is mainly determined by the accuracy of abrasive wheel in the form-grinding process. Thus, the shaped wheel dressing becomes one of the key points in the form-grinding process. In order to grind the revolving curved surfaces grooves whose cross-sectional profiles are steep and smooth, a new NC dresser with three NC axes is developed by adding a swing axis on the basis of NC external cylindrical grinding machine. A wheel of any desired convex profile can be dressed when using the Diaform single-diamond dresser and the possible geometrical interference between the single-diamond dresser and wheel can be eliminated. By analyzing the influence of installation accuracy on the profile accuracy, a method of comprehensive error compensation is presented. The comprehensive errors can be diminished greatly to improve the profile accuracy by means of error compensation. It is proved in the experiments that the precision requirements of grinding the formed surfaces grooves can be met.
Abstract: Improvement in grinding efficiency is very important to economically produce precision parts. This paper proposes a new table-motion control system for reducing non-machining time in the surface-grinding process and describes the results of performance tests of the system. The table-motion is adaptively controlled so that the table stroke is shifted along a workpiece shape. That is, an AE signal is emitted from the contact zone between a grinding wheel and a workpiece and is diminished when the wheel leaves the workpiece. When the signal level becomes less than a preset trigger level, a command is sent to a table controller to reverse the table-motion. By using the proposed system, unnecessary table over-travel is successfully eliminated and total machining time is reduced by 22 to 38 percent.
Abstract: In order to eliminate unnecessary table-over-travel of a surface grinding machine, the
authors previously developed an adaptive table-reciprocation-control system using a hydrophone. The system eliminated the over-travel and reduced grinding time by 20-40%. However, during the stage of the grinding-wheel approach to a workpiece the system did not work. In order to improve the efficiency and reliability of the system, a fluid-flow stabilizer and a new coolant-supply nozzle have been developed and their performances were experimentally investigated. By using these devices, the reciprocation-control system showed its capability even during the stage of the grinding-wheel approach and this ability improved the system efficiency and reliability.
Abstract: Single-crystal diamond tools can be used for cutting high precise parts with high efficiency, but it is very difficult to abrade it, which is one of study purposes in this paper. This project can be done on the high precise machine tools by using a diamond abrasive wheel with super fine grain size. In this paper, the abrading mechanism is represented, an efficient abrasive method is invented, the major factors which have an important effect on abrasive efficiency and accuracy are discussed, such as abrasive wheel grain size, bonding agent, hardness, speed, pressure and feeding speed etc and some results raising abrasive efficiency and accuracy are obtained. By using the single-crystal diamond tool abraded by author, the degree of roughness of the parts can come up to Ra0.05.
Abstract: Effects of TiH2 on the mechanical properties and microstructures of Fe-based diamond composites as well as the performance of diamond segments in circular sawing of granites are presented in this paper. Experimental results reveal that the addition of 2%TiH2 into the Fe-based matrix leads to decreases in the mechanical properties of both matrix and diamond composites. The wear resistance of the saw-blade segments decreases by 7.3%. Microscope observations reveal that the specimen without TiH2 shows fewer pores and denser structures in the base matrix. The fracture surfaces of the bending test specimens exhibit ductile cup and cone behavior and strong bonding between the matrix and diamond. SEM micrographs indicate that there are much more pull-outs of diamond grits, much more serious wear of diamond particles and erosion of metal matrix on the worn surface of saw-blades segments with 2% TiH2 in the matrix.
Abstract: This paper describes an experimental investigation of the effect of ultrasonic elliptic
vibration of the shoe on the friction between the shoe and the workpiece in ultrasonic
elliptic-vibration shoe centerless grinding, a new centerless grinding technique proposed previously by the present authors. In the new technique, an ultrasonic elliptic-vibration shoe is employed to control the workpiece rotational speed as a regulating wheel does in conventional centerless grinding. The grinding accuracy is affected significantly by the workpiece rotation stability, which is dependent on the frictional force between the workpiece and the ultrasonic elliptic-vibration shoe. The issue relating to the friction between the workpiece and the shoe is therefore very important in the complete establishment of the new centerless grinding technique. In the present work, in order to clarify the effect of ultrasonic elliptic vibration of the shoe on the frictional coefficient and to determine the appropriate ultrasonic elliptic vibration conditions, a measurement apparatus was built up in-house and used to measure the frictional coefficient under the presence and absence of the ultrasonic elliptic vibration. The measurement results indicated that the frictional coefficient decreases with increase in the size of the ultrasonic elliptic motion, and a shape of the elliptic motion, in which the frictional coefficient reaches maximum, exists.
Abstract: Eco-efficiency of manufacturing processes is increasingly important. Here grinding is
supposed to be unfavorable because of the need for coolant and a high energy consumption per removed material volume. Nevertheless, it can be not be substituted by an alternative process due to the superior quality of ground parts. The overall eco-efficiency of grinding can be improved by different approaches. A better understanding of grinding processes and a modified setup of the process chain minimizes the material to be removed by grinding. Design changes of the machine tool can significantly reduce the energy consumption of additional devices as coolant supply units without a loss of flexibility. Adapted process parameters increase eco-efficiency and can also improve cost effectiveness while maintaining part quality.
Abstract: Nano ceramics possessed ascendant mechanical property and physical characteristics contrast with engineering ceramics, so it has extensive application prospect in various industries. On the basis of applying the indentation fracture mechanics to analyze the removal mechanics of ceramic material, this paper analyzed the critical ductile grinding depth of the nano ZrO2 ceramics. Adopting ultrasonic composite processing we describe the influence of different processing
parameters and grain size of diamond wheel on the grinding forces and surface roughness. Based on the grinding forces and surface roughness the grinding process with and without vibration is analyzed. By means of SEM and AFM the surface character and critical ductile grinding depth of nano ZrO2 ceramics are also discussed. The paper supplied the theoretical and experimental basis for the grinding of the large-sized ultraprecision plate structure of nano ZrO2 ceramics (nm).
Abstract: Aspherical parts are installed in various optical instruments. At present, a higher form
accuracy is required for aspherical parts to improve the resolution of the optical instruments. To meet this demand, an arc envelope grinding method has been developed. In the arc envelope grinding process, a spherical shaped grinding wheel is used and the form error of the cross-sectional profile of the grinding wheel is transcribed to the workpiece profile. Therefore, the grinding wheel should be trued previously. However, the form error of the grinding wheel cannot be removed perfectly. To reduce the affect of the form error of the grinding wheel, compensation grinding must be carried out. In this work, the wheel path of a new compensation grinding method is proposed for a high NA value of the workpiece. Tests using the new compensation grinding method demonstrate the reduction in the form error of aspherical parts.
Abstract: Electrically conductive cutting edges diamond grinding wheels (EC-cutting edges D
wheels) have properties such as, 1) convenient precise forming by EDM, 2) realization of high cutting edge density, 3) sufficiently large chip pockets along with fine cutting edges on large diamond grits, 4) contact sensing of the cutting edges with workpiece due to electrical conductivity, 5) expected application to the grinding of various types of steels due to high thermal resistance. Until now, the
grinding ability of the sharp edges generated on the electrically conductive CVD diamond thick film wheel by electrodischarge trueing (ED trueing) was confirmed by grinding experiments using a small diameter lapping wheel and a small diameter disk wheel. In this research work, metal bonded diamond wheels containing boron doped electrically conductive diamond (EC diamond) grits, which possess high oxidation temperature, were trial manufactured. From the results of grinding test for an optical glass (BK7), it was found that the wear and grinding force for the EC diamond grits wheel were significantly low compared to a conventional diamond grits wheel. Furthermore, from the results of the investigation on ED trueing performance, a high trueing efficiency along with the possibility of cutting edge tip formation was confirmed.