Error Compensation of Thin Plate-shape Part with Prebending Method in Face Milling

Low weight and good toughness thin plate parts are widely used in modem industry, but its flexibility seriously impacts the machinability. Plenty of studies locus on the influence of machine tool and cutting tool on the machining errors. However, few researches focus on compensating machining errors through the fixture. In order to improve the machining accuracy of thin plate-shape part in face milling, this paper presents a novel method for compensating the surfacc errors by prebending the workpiece during the milling process. First, a machining error prediction model using finite element method is formulated, which simplifies the contacts between the workpiece and fixture with spring constraints. Milling fbrces calculated by the micro-unit cutting force model arc loaded on the error prediction model to predict the machining error. The error prediction results are substituted into the given formulas to obtain the prebending clamping forces and clamping positions. Consequently, the workpiece is prebent in terms of the calculated clamping forces and positions during the face milling operation to reduce the machining error. Finally, simulation and experimental tests are carried out to validate the correctness and efficiency of the proposed error compensation method. The experimental measured flatness results show that the flatness improves by approximately 30 percent through this error compensation method. The proposed mcthod not only predicts the machining errors in face milling thin plate-shape parts but also reduces the machining errors by taking full advantage of the workpiece prebending caused by fixture, meanwhile, it provides a novel idea and theoretical basis for reducing milling errors and improving the milling accuracy.

Effects of FDM-3D printing parameters on mechanical properties and microstructure of CF/PEEK and GF/PEEK

Fused deposition modeling(FDM)has unique advantages in the rapid prototyping of thermoplastics which have been developed in diverse fields.However,although great efforts have been made to optimize FDM process,the mechanical properties of printed parts are limited by the weak interlamination bonding as well as the poor performance of raw filaments used,such as acrylonitrile butadiene styrene(ABS),polylactic acid(PLA).Adding fibers into thermoplastic matrix and preparing high-performance filaments have been indicated to enhance the properties of fabricated parts.Recently,heat-resistant polyetheretherketone(PEEK)and its fiber reinforced composites were proposed for FDM process due to overcoming the limitation of equipment and process.However,few researches have been reported on the effects of FDM-3 D printing parameters on the mechanical properties of fiber reinforced PEEK composites.Therefore,5 wt%carbon fiber(CF)and glass fiber(GF)reinforced PEEK composite filaments were prepared respectively in this study.The effects of various printing parameters including nozzle temperature,platform temperature,printing speed and layer thickness on the mechanical properties(including tensile strength,flexural strength and impact strength)were surveyed.To analyze the microstructure and failure reasons of printed CF/PEEK and GF/PEEK samples,the tensile fractured surfaces were investigated via scanning electron microscope(SEM).