Abstract

The ability to predict the grinding force for hard and brittle materials is important to optimize and control the grinding process. However, it is a difficult task to establish a comprehensive grinding force model that takes into account the brittle fracture, grinding conditions, and random distribution of the grinding wheel topography. Therefore, this study developed a new grinding force model for micro-grinding of reaction-bonded silicon carbide (RB-SiC) ceramics. First, the grinding force components and grinding trajectory were analysed based on the critical depth of rubbing, ploughing, and brittle fracture. Afterwards, the corresponding individual grain force were established and the total grinding force was derived through incorporating the single grain force with dynamic cutting grains. Finally, a series of calibration and validation experiments were conducted to obtain the empirical coefficient and verify the accuracy of the model. It was found that ploughing and fracture were the dominate removal modes, which illustrate that the force components decomposed are correct. Furthermore, the values predicted according to the proposed model are consistent with the experimental data, with the average deviation of 6.793% and 8.926% for the normal and tangential force, respectively. This suggests that the proposed model is acceptable and can be used to simulate the grinding force for RB-SiC ceramics in practice.

Highlights

  • Reaction-bonded silicon carbide (RB-SiC) is a good candidate material for large space optical mirrors due to their high strength, high thermal conductivity, enhanced radiation stability, and thermal shock resistance characteristics [1,2,3]

  • Most of above-mentioned models concerned grinding of metallic materials, which just involved rubbing, ploughing, and chip formation stages, whereas brittle fracture is the most significant distinction removal mechanism between ceramics and metallic materials

  • In order to obtain a predictive model for ceramics, an improved theoretical force model was proposed in this paper, which takes the random distribution of abrasives, grinding trajectory, and different material deformation stages into consideration

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Summary

Introduction

Reaction-bonded silicon carbide (RB-SiC) is a good candidate material for large space optical mirrors due to their high strength, high thermal conductivity, enhanced radiation stability, and thermal shock resistance characteristics [1,2,3]. The adoption of them results in the prediction of hard and brittle materials having deviations This indicates that the transition from ductile deformation to the brittle fracture removal mode must be considered when modelling the grinding force for ceramics. It can be determined that, considering the brittle fracture characteristic while, at the same time, combining the random distribution of grinding wheel grains, is the major impediment to modelling the grinding force for RB-SiC ceramics. In order to obtain a predictive model for ceramics, an improved theoretical force model was proposed in this paper, which takes the random distribution of abrasives, grinding trajectory, and different material deformation stages into consideration.

The Critical Depth for the Elastic to Plastic Transition
The Critical Depth of Cut for Chip Formation
The Critical Depth for the Ductile to Brittle Transition
The Maximum Undeformed Chip Thickness in Micro-Grinding
Contact Force in the Brittle Zone
The Parameters of the Cutting Edge Radius and Cone Angle
Experimental Setup and Procedure for Model Validation
The Topography of GGrriinnddiinngg RRBB--SSiiCC
Force Model Calibration and Verification
Findings
Conclusions
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