Formation mechanism and modelling of exit edge-chipping during ultrasonic vibration grinding of deep-small holes of microcrystalline-mica ceramics

Crack extension is critical in determining surface forming process and machined surface quality of hard brittle materials. However, there is still a lack of research on this subject. In this work, the effect of crack extension on surface formation mechanism and surface morphology of silicon nitride ceramics was investigated via longitudinaltorsional composite ultrasonic-assisted mill-grinding, and reconstruction model of machined surface morphology considering crack extension was proposed. This model was quantitatively characterized and evaluated by the average roughness Sa and the kurtosis Sku. It is found that simulation results considering crack expansion were in good agreement with experimental results. Average relative errors in average roughness and kurtosis were found to be 7.95% and 9.46%, respectively. Primary effect analysis was performed to understand the influence of process parameters on machined surface morphology. It is found that ultrasonic vibration leads to changes in shear angle and shear velocity of abrasive grains, thereby changing machined surface morphology. Results presented here provide practical method for predicting and controlling machined surface quality during precision machining of ceramic materials.

Section: Introductionmentioning

confidence: 99%

Effect of crack propagation on surface formation mechanism and surface morphology evaluation of longitudinal–torsional composite ultrasonic mill grinding of Si3N4

Qiao²,

Zheng³

et al. 2023

“…Yang et al [10] established a model of the contact rate of abrasive particles and workpieces in the process of ultrasonic vibration assisted grinding. Dong et al [11] analyzed the edge-cutting mechanism of an ultrasonic vibration grinding hole exit through finite element simulation, provided theoretical guidance for the efficient and precise machining of small and deep holes in hard and brittle materials. Yu et al [12] proposed an axial ultrasonic vibration assisted polishing method.…”

Section: Introductionmentioning

confidence: 99%

Study on high-speed vibration cutting of titanium alloy considering cutting edge radii

Cheng

et al. 2022

Ultrasonic vibration cutting (UVC) is an advanced machining method used to improve machining performance and surface quality in the manufacturing industry. However, the separation characteristic disappears when the cutting speed exceeds the maximum vibration speed, limiting its use in low-speed machining. Therefore, this study used the finite element method (FEM) to study the high-speed vibration cutting (HVC) processing performance of titanium alloys.High-speed vibration cutting is a precision machining method with a smaller cutting depth and feed rate, so it is necessary to consider the influence of the cutting edge radii on the cutting process. The cutting edge radii on high-speed vibration cutting and the influence of the traditional cutting process is discussed. The results show that the change in the minimum uncut chip thickness caused by changing the cutting edge radii during precision cutting has a significant influence on the experimental results. In addition, a simulation model was established and a comprehensive numerical analysis and comparison of high-speed vibration cutting, ultrasonic vibration cutting and conventional cutting (CC) were performed with respect to tool wear, cutting temperature, cutting force and stress distribution. The simulation results indicate that the tool wear depth of traditional cutting during high-speed cutting is up to three times that of high-speed vibration cutting, and high-speed vibration cutting weakens the influence of the cutting edge radii.But this new vibration cutting method did not significantly reduce the cutting temperature under dry cutting conditions.

“…UAG is a hybrid process that combines diamond grinding with ultrasonic machining [3][4][5]. Over the last few decades, many studies have confirmed that UAG offers many advantages for the processing of hard and brittle materials such as low grinding force, high machining quality, and low surface/ subsurface breakage.…”

Section: Introductionmentioning

confidence: 99%

Experimental studies on material removal mechanisms in ultrasonic assisted grinding of SiC ceramics with a defined grain distribution brazed grinding wheel

Ding

Zhang

2021

Ultrasonic assisted grinding (UAG) is one of the most suitable methods for the processing of hard and brittle materials such as silicon carbide (SiC). During UAG of SiC, the machining quality is directly determined by the material removal mechanism. However, the research on the material removal mechanism for UAG of SiC is still not sufficiently developed. To achieve better comprehension of the material removal mechanism in UAG of SiC, this study conducted both UAG and conventional grinding (CG) tests with a brazed grinding wheel with defined grain distribution. The material removal mechanism in UAG of SiC was studied by comparing the ground surface/subsurface micro-morphology, surface roughness, grinding force, and specific grinding energy between both processes. The results showed that the material removal mechanism experienced a transition from ductile removal to brittle fracture with increasing undeformed chip thickness in both UAG and CG. In addition, the ground surface roughness, grinding force, and subsurface breakage size increased with increasing undeformed chip thickness, while the specific grinding energy first decreased rapidly and then stabilised. Compared with conventional grinding, UAG always resulted in lower surface/subsurface breakage, surface roughness grinding force, and specific grinding energy under identical operating conditions.