Papers by Keyword: Grinding Force

Abstract: In this paper, plunge grinding experiment was conducted on 20CrMnTi with monolayer brazed cubic boron nitride (CBN) wheel. Surface integrity was evaluated through morphology observing and roughness testing. It is found that surface roughness Ra is lower than 0.8μm. Grinding forces were measured and the effects of process parameters (i.e. workpiece speed and depth of cut) on grinding forces were studied. The changing regulation of specific grinding energy with the increase of equivalent chip thickness was revealed. The result shows that both grinding force and specific energy are lower comparing with white fused alumina (WA) wheels. In general, monolayer brazed CBN wheels perform better in grinding of 20CrMnTi than WA wheels.

Abstract: Grinding test was carried out to study the grinding of granite with single diamond grain. Forces were measured to investigate the mean normal and tangential forces acted on the diamond grain. The relationship between the forces and either spindle speed or the maximum thickness of the undeformed chip produced by a diamond grain was discussed. The digital models of granite were constructed by discrete element method. Based on the model, two-dimensional and 3-D analysis was carried out to simulate the grinding process with the single diamond grain. The simulation results were compared with experimental data, and some useful conclusions were obtained: the 3-D results agree well with the experiment data at the sameand largeas well as the sameand large; the 3-D and 2-D results are comparable to the experiment data at other machining parameters..

Abstract: Ultrasonic assisted grinding experiments were carried out to evaluate the effects of the ultrasonic vibration (UV) on the face grinding characteristics of nickel based superalloy of Rene77. In experiments, an electroplated cBN grinding wheel was ultrasonically vibrated dominantly along its axis. The experimental results indicated that the X-axis and Y-axis components of grinding forces with UV were smaller by 44.5% and 31.6%, respectively, than those without UV. The usual fractures and debris on the surface of workpiece disappeared and the work-surface roughness Ra was decreased by 42.3% once the UV was applied. The abrasion of the grinding wheel without UV is more serious than that with UV.

Abstract: In this paper, experiments are conducted to study the characters of Ultrasonic Assisted Grinding (UAG) and Conventional Grinding (CG), diamond grinding wheel is used in experiments, grinding forces and surface roughness are measured in both UAG and CG. The effects of different parameters on grinding force, surface roughness and force ratio are discussed. The results show that the grinding force and surface roughness in UAG is smaller than those in CG. The force ratio in UAG is lower than that in CG, which reveals that the grinding wheel has a good wear-resistant property in UAG process.

Abstract: Based on the orderly distribution alumina bubbles in working layer the porous composite-bonded CBN wheels were fabricated and grinding experiments of nickel-based alloy were carried out in comparison of the vitrified counterpart. Results show that the grinding force decreases and increases respectively with the increasing wheel velocity and depth of cut. The specific grinding energy reduces graduately from 465 to 93 J/mm³ when the maximun underformed chip thickness increases from 0.4 to 1.7 μm. Compared to the vitrified CBN wheel, the grinding forces, temperatures and specific grinding energy of the porous composite-bonded CBN wheel are always lower than that of the vitrified one. Its attributed to the graphite lubricating and alumina bubbles pore-forming effects. The larger chip storage space, sharper grit edge and less adhesion on the wheel surface surpport the advantages of the porous CBN wheel.

Abstract: In the low-speed grinding process, the force generated when the wheel grinding the workpiece is the result of sliding friction, plough and cutting. While in the actual study, the cutting process has attracted extensive attention. Impact effect to the entire grinding process on the contact is ignored so that the error exists between the calculation grinding force and the measured grinding force. Basing on the shock effect to the grinding process, the paper divides the contact area into impact area and cutting area. And the model of impact load generated from single grit is built. Moreover, the grinding force theoretical calculation model and total grinding force mathematical model is also constructed by analyzing the impact load affecting on the grinding force mechanism. Finally experimental study verifies the correctness of theoretical analysis.

Abstract: Grinding forces characteristics in elliptical ultrasonic assisted grinding (EUAG) of sapphire are investigated experimentally. The EUAG is a new grinding method proposed by the present authors in which an elliptical ultrasonic vibration is imposed on the workpiece by using an elliptical ultrasonic vibrator. In this paper, grinding experiments under the presence/absence of ultrasonic vibration assistance are performed. The effects of the vibration amplitude and grinding parameters such as the depth of cut, the grinding wheel speed on the grinding forces, grinding force ratio F_n/F_t are clarified. The obtained conclusions are as follows: the grinding forces during EUAG lowers to 50% and grinding forces ratio becomes reduced by 33% compared that during conventional grinding (CG); the grinding forces during EUAG have the less variation rate than those during CG as grinding parameters change; higher grinding wheel speed causes the larger grinding forces in CG, but has little effect on the variation of grinding forces in EUAG. By using EUAG method, the grinding forces and force ratio are greatly decreased, and surface quality is better, meaning that grindability of sapphire material is improved.

Abstract: High speed grinding technology has great help about high speed grinding in application to the grinding of titanium alloy. In order to search the efficiency way to grinding the difficult to grinding material, the high speed grinding tests of titanium alloy Ti6Al4V were systematically conducted by using three wheels: brazed CBN wheel, ceramic bond CBN wheel and electroplated CBN wheel. Different equations of the maximum undeformed chip thickness a_gmax are adopted for different wheels based on their topography. The experiment results revealed that the grinding forces are increasing following the increasing of a_gmax, and the forces decrease slightly while the grinding speed v_s rise, the specific energy decrease with an increase in undeformed chip thickness firstly then reduce slightly. Particllarly, the removal rate is highest for brazed CBN wheel when the same specific energy is consumed. These phenomena indicate that with adopting the reasonable a_gmax, high speed grinding with brazed CBN grinding wheel can improve the grinding efficiency and reduce the energy.

Abstract: In order to reveal the theoretical nature of ultrasonic ELID composite grinding which is an efficient grinding technology, this paper theoretically analyzes a single grains motion characteristics in the process of internal cylindrical grinding under axial vibration and established a single grits kinematic equation. Then the grits trajectory is draw by matlab, and the contact length of the grinding wheel and the workpiece is achieved. At the same time the electrolysis parameters are introduced into the dynamic number of effective grits with analysis its electrochemical action. Thereby a force model for the ultrasonic ELID composite internal cylindrical grinding is established. Through analysis the model it is easy to find the force is fluctuated periodically with electrical current changing.

Abstract: An experimental study of quartz glass grinding with ultrasonic torsional vibration assistance is presented. The grinding forces and surface roughness are measured. The results show that the grinding force and surface roughness with ultrasonic torsional vibration assistance are much less than those in conventional grinding. The grinding force increases with the feed rate of workpiece and the depth of grinding, and decreases with the speed of wheel spindle. This research indicates that the ultrasonic torsional vibration-assisted grinding can enhance grinding performance and be an effective method for the machining of hard and brittle materials.