Fabrication Technology Of The Wheel With Controlled Abrasive Cluster And Its Grinding Performance

With grinding technology developing toward high speed, high efficiency and high accuracy, and grinding needs from booming new materials, challenges are posed to the conventional grinding wheels. On the one hand, on the traditional fixed abrasive wheel, especially for precision grinding, the grain is so little and the chip clearance is so small that the tool surface are prone to be loaded, causing the tool invalid and the workpiece burned even the normal machining process unable to continue. On the other hand, the accuracy of traditional single layer superabrasive wheel depends on the accuracy of wheel substrate significantly. To solve these problems in traditional grinding wheel, a wheel with controlled abrasive cluster is proposed in this paper, on which the distance between the grits or abrasive clusters and the distribution pattern are set suitably with practice. Monolayer or multilayer abrasives are feasible and the chip clearance is ensured properly.Firstly, the wheel with controlled abrasive cluster is characterized by parameters and the relationship of the abrasive-cluster's main parameters is analyzed. Also the effect of the main parameters of the wheel surface on the grinding performance is studied at the point of view of grinding theory and grit kinematic analysis. A characterization and evaluation system was established, which contains such as diameter of abrasive cluster, the effective abrasive index, the kinematic tracks of the abrasive clusters and so on. The density of grinding tracks of cluster on the wheel with different distribution patterns, with different distance between the clusters and different rotation speed of wheel, are calculated and analyzed. They provide a basis for choosing the parameters of the wheel design and machining.An economical and easy fabrication process of selective composited electro-deposition is proposed and the main processes are studied. The method and processes of mask fabrication are explored and their available ranges are given based on the following three aspects:the screen printing technology, the photolithography technology and the laser drilling. The main parameters of pulse plating of Nickel-Cobalt alloy are optimized and chosen by orthogonal experiments. The process specification for the wheel fabrication is set and a semi-automatic electroplating equipment fulfilling for small batch experiment and production is developed. Some samples of the wheel with controlled abrasive cluster are fabricated successfully.To reduce or eliminate the run-out error of the wheel working surface after it to be assembled, the multi-layer abrasive electroplated Ni-Co wheel with controlled abrasive cluster is developed. And then, the process of electrolytic dressing is proposed for the Ni-Co electroplated wheel based on electrolytic machining. By analyzing the standard electrode potential and testing the polarization curve, the removal feasibility of electroplated Ni-Co alloy by electrolytic dressing is studied. In the experiment of electrolytic dressing on a straight wheel, the surface run-out error after assembled on the grinder spindle has a reduction by 61.5% compared with dressed before, which improve the wheel use accuracy significantly. In the experiment of electrolytic dressing on multi-layer abrasive wheels, the Ni-Co alloy bonding of the wheel is removed uniformly and the average protrusion height is up to 42.9% of the grain size.In order to fulfill with the needs of machining of carbon fiber reinforced plastics (CFRP) and solve the difficulties of dry grinding of CFRP, grinding experiments by using the wheel with controlled abrasive cluster are conducted. The results show that the grinding temperature is dramatically reduced. The steady axial force and good surface integrity are obtained by using the wheel with controlled abrasive cluster, and the surface roughness Ra of the workpiece keeps in a range from 0.8 to 1.3μm. There is no soften resin and chips because the grinding temperature is lower than the soften temperature of the epoxy resin. The space among the clusters serve as room and access for grinding chips accommodation and removal, which avoids wheel loading effectively. Due to the excellent performance of the new wheel on grinding of CFRP, the wheel with controlled abrasive cluster is equipped on the high speed drilling and grinding CNC machine typed ZM1000 and applied in grinding of a certain cylindraceous composites part.