Contact Mechanism of Rail Grinding with Open-Structured Abrasive Belt Based on Pressure Grinding Plate

The current research of abrasive belt grinding rail mainly focuses on the contact mechanism and structural design.Compared with the closed structure abrasive belt grinding,open-structured abrasive belt grinding has excellent performance in dynamic stability,consistency of grinding quality,extension of grinding mileage and improvement of working efficiency.However,in the contact structure design,the open-structured abrasive belt grinding rail using a profiling pressure grinding plate and the closed structure abrasive belt using the contact wheel are different,and the contact mechanisms of the two are different.In this paper,based on the conformal contact and Hertz theory,the contact mechanism of the pressure grinding plate,abrasive belt and rail is analyzed.Through finite element simulation and static pressure experiment,the contact behavior of pressure grinding plate,abrasive belt and rail under single concentrated force,uniform force and multiple concentrated force was studied,and the distribution characteristics of contact stress on rail surface were observed.The results show that under the same external load,there are three contact areas under the three loading modes.The outer contour of the middle contact area is rectangular,and the inner contour is elliptical.In the contact area at both ends,the stress is extremely small under a single concentrated force,the internal stress is drop-shaped under a uniform force,and the internal stress under multiple concentration forces is elliptical.Compared with the three,the maximum stress is the smallest and the stress distribution is more uniform under multiple concentrated forces.Therefore,the multiple concentrated forces is the best grinding pressure loading mode.The research provides support for the application of rail grinding with open-structured abrasive belt based on pressure grinding plate,such as contact mechanism and grinding pressure mode selection.

Allowance Extraction Considering of Inner and Outer Contour and Experimental Research on Belt Grinding of Hollow Blade

Aero-engine fan blades of ten use a cavity structure to improve the thrust-to-weight ratio of the aircraft.However,the use of the cavity structure brings a series of difficulties to the manufacturing and processing of the blades.Due to the limitation of blade manufacturing technology,it is difficult for the internal cavity structure to achieve the designed contour shape,so the blade has uneven wall thickness and poor consistency,which affects the fatigue performance and airflow dynamic performance of the blade.In order to reduce the influence of uneven wall thickness,this paper proposes a grinding allowance extraction method considering the double dimension constraints(DDC)of the inner and outer contours of the hollow blade.Constrain the two dimensions of the inner and outer contours of the hollow blade.On the premise of satisfying the outer contour constraints,the machining model of the blade is modified according to the distribution of the inwall contour to obtain a more reasonable distribution of the grinding allowance.On the premise of satisfying the contour constraints,according to the distribution of the inwall contour,the machining model of the blade is modified to obtain a more reasonable distribution of the grinding allowance.Through the grinding experiment of the hollow blade,the surface roughness is below Ra0.4μm,and the contour accuracy is between-0.05~0.14 mm,which meets the processing requirements.Compared with the allowance extraction method that only considers the contour,the problem of poor wall thickness consistency can be effectively improved.It can be used to extract the allowance of aero-engine blades with hollow features,which lays a foundation for the study of hollow blade grinding methods with high service performance.

A Novel Approach for the Fabrication of Sharkskin Structured Bionic Surfaces with Hydrophobic Wettability:Laser Processing and Ordered Abrasive Belt Grinding

A new process for the fabrication of sharkskin bionic structures on metal surfaces is proposed.The sharkskin bionic surface was successfully machined on the surface of IN718 by laser sequencing of the abrasive belt surface,laser processing of the layered scale-like structure,and ribbed texture grinding.The flexible contact properties of belt grinding allow ribbed structures to be machined uniformly on a hierarchical,scale-like microstructure.Sharkskin bionic microstructures with radii greater than 75µm were prepared after parameter optimisation.The influence of processing parameters on the geometrical accuracy of the microstructure was investigated,the microstructure microform and elemental distribution were analyzed,and the relationship between the ribbed microstructure and chemical properties of the surface of the bionic sharkskin on wettability was revealed.The results indicate that reducing the laser power and increasing the laser scan rate can reduce the laser thermal effect and improve the microstructure processing accuracy.The laser ablation process is accompanied by a violent chemical reaction that introduces a large amount of oxygen and carbon elements and infiltrates them at a certain depth.The wettability of the surface undergoes a transition from hydrophilic(contact angle 69.72°)to hydrophobic(contact angle 131.56°)due to the adsorption of C-C/C-H and the reduction of C=O/O=C-O during the placement process.The ribbed microstructure changes the solid-liquid contact on the surface into a solid-liquid-gas contact,which has an enhanced effect on hydrophobicity.This study is a valuable guide to the processing of hydrophobic layered bionic microstructures.

Single-grain cutting based modeling of abrasive belt wear in cylindrical grinding

A systematic wear model of the cylindrical grinding process with an alumina abrasive belt from the perspective of single grain sliding wear was established in this study.The model consists of three parts:a single cutting force model derived by applying a stress integration method,a single grain wear height analysis based on the wear rate of alumina,and a grinding mileage prediction of multiple grains with Gaussian distributed protrusion heights.Cutting force,single grain wear height and full‐size grinding mileage verification experiments were conducted.The results indicated that the established model was in reasonable agreement with the experimental outcomes,which suggests that this model could be useful in the industry to predict the wear process of abrasive belts.

The Method and Experiment Research on Down-stroke Abrasive Belt Grinding under Micro Feeding for Noise Reduction Surface

This paper proposes a down-stroke abrasive belt grinding under micro feeding for noise reduction surface.Firstly,a physical model of processing under micro feeding for noise reduction structure was established.Based on the flexible contact characteristics of abrasive belt grinding and Hertz contact theory,a mathematical model suitable for this method was established,considering vibration and abrasive belt wear.Secondly,a simulation analysis was carried out.Then,an experimental platform was built to analyze the influence of process parameters on surface roughness and surface microstructure,with the model verified.Finally,the propeller with pit structure was simulated,and the noise reduction performance of the propeller under this method and general abrasive belt grinding was compared and analyzed.The results show that the maximum error of the model based on proposed method does not exceed 10%,and the coincidence degree of the minimum error point can reach 90%at lower feed speed and higher linear velocity of the abrasive belt.The noise reduction effect of the propeller with pit-shaped surfaces can reach 35%.Through the above analysis,the proposed method can be used for the processing of noise reduction surfaces.

A Path Planning Method for Robotic Belt Surface Grinding

The flexible contact and machining with wide strip are two prominent advantages for the robotic belt grinding system, which can be widely used to improve the surface quality and machining efficiency while finishing the workpieces with sculptured surfaces. There lacks research on grinding path planning with the constraint of curvature. With complicated contact between the contact wheel and the workpiece, the grinding paths for robot can be obtained by the theory of contact kinematics. The grinding process must satisfy the universal demands of the belt grinding technologies, and the most important thing is to make the contact wheel conform to the local geometrical features on the contact area. For the local surfaces with small curvature, the curve length between the neighboring cutting locations becomes longer to ensure processing efficiency. Otherwise, for the local areas with large curvature, the curve length becomes shorter to ensure machining accuracy. A series of planes are created to intersect with the target surface to be ground, and the corresponding sectional profile curves are obtained. For each curve, the curve length between the neighboring cutting points is optimized by inserting a cutter location at the local area with large curvatures. A method of generating the grinding paths including curve length spacing optimization is set up. The validity is completely approved by the off-line simulation, and during the grinding experiments with the method, the quality of surface is improved. The path planning method provides a theoretical support for the smooth and accuracy path of robotic surface grinding.