Experimental and theoretical investigation on critical cutting force in rotary ultrasonic drilling of brittle materials and composites

2018 ◽  
Vol 135 ◽  
pp. 555-564 ◽  
Author(s):  
Jianjian Wang ◽  
Jianfu Zhang ◽  
Pingfa Feng ◽  
Ping Guo
2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Liping Liu ◽  
Bin Lin ◽  
Fengzhou Fang

A novel air bearing workbench used in rotary ultrasonic drilling of advanced ceramics was designed to constantly and sensitively control the cutting force. Compared with traditional feed systems, the novel air bearing workbench features an aerostatic guide and a pneumatic actuator, so that it only overcomes the air damping when the cutting force is balanced. Thus, it can sensitively and constantly control the cutting force for rotary ultrasonic drilling of advanced ceramics. The aerostatic guide, which determines the eccentric bearing capacity and stiffness of the workbench, is the most important part. The forces applied on the aerostatic guide faces were analyzed to calculate the bearing capacity and stiffness of the workbench using varying gas film thicknesses with finite element method (FEM). Based on the result of the analysis, the best gas film thickness of the aerostatic guide was designed to be 30 μm. The real eccentric bearing capacity and stiffness of the workbench were measured. The error between experimental results and the FEM results was within 12%.


2012 ◽  
Vol 433-440 ◽  
pp. 2034-2041 ◽  
Author(s):  
Cheng Long Zhang ◽  
Ping Fa Feng ◽  
Zhi Jun Wu ◽  
Ding Wen Yu

Rotary ultrasonic machining is a hybrid machining process that combines diamond grinding and ultrasonic machining. The mathematical predictive material removal rate models have been developed in rotary ultrasonic machining with a constant pressure. However, there is no report on mathematical predictive cutting force model in rotary ultrasonic drilling at a constant feedrate presently. Since cutting force can not only reflect the processing state, but also affect the machined surface quality, it is necessary to develop a mathematical model for predicting cutting force which can forecast the machining results. This paper presents a mathematical model to predict the cutting force in rotary ultrasonic machining. On the basis of this model, the relations between cutting force and controllable machining parameters are researched by numerical computation method. This paper also researches the influences of spindle speed and feedrate on cutting force by experiments. The results observed through the experiments agree well with the relations generated from the mathematical model, which verify the developed model.


2011 ◽  
Vol 230-232 ◽  
pp. 221-225 ◽  
Author(s):  
Cheng Long Zhang ◽  
Ping Fa Feng ◽  
Zhi Jun Wu ◽  
Ding Wen Yu

Rotary ultrasonic machining process, regarded as one of the effective processing methods for hard-brittle materials, is introduced into drilling K9 glass in this paper. The effective cutting velocity, cutting depth, and cutting length of single diamond particle are determined by analyzing the kinematics characteristic of diamond tool in rotary ultrasonic drilling (RUD). Experiments are conducted to study the influences of process variables (spindle speed, feedrate) on cutting force, chipping size, and surface roughness in RUD. As comparison study, the processing performances between RUD and diamond drilling are also discussed. The experimental results show that the RUD process can significantly reduce cutting force and the value of chippings size, which inferred that RUD process can improve machining efficiency and make the machining cost lower. It is also concluded that the effective cutting depth of diamond particles is the main factor for surface roughness in RUD of K9 glass.


Author(s):  
Miloš Pjević ◽  
Ljubodrag Tanović ◽  
Goran Mladenović ◽  
Biljana Marković

The paper presents experimental results of microcutting brittle materials (granite). The analysis was conceived on the observed interaction between the workpiece and two tools of different shapes. Experiment was based on scratching the workpiece surface with diamond tools. Applied tools had tip radius R0.2 and R0.15 mm. The experiment determined the changes in the value of perpendicular and tangential components of the cutting force based on the geometric properties of tools, as well as the changes of the specific energy of microcutting granite (Jošanica and Bukovik types). The experiment has shown that reduction of tool radius causes reduction of the cutting force intensity and specific cutting energy. Because of its physical/mechanical properties, more energy is required for micromachining granite “Jošanica” than “Bukovik.” Based on the topography of the surface, the value of critical tool penetration depth was established, after which the brittle fracture is no longer present. For granite “Jošanica” values of critical penetration depth are 6 and 5 μm when micromachining with tools R0.2 and R0.15 mm, while for Bukovik those values are 6.5 and 5.5 μm. The paper should form the basis for understanding the phenomena which occur during microcutting brittle materials.


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