Zhanjiang Yu

Superhydrophobic surface prepared by micromilling and grinding on aluminium alloy

An efficient method for processing superhydrophobic surface is presented in this paper, which can realise the microstructure machining on a large area. First, the microgroove arrays were processed by high speed precision micromilling machine on the surface of the aluminium alloy. Then, the surface of the microgroove was ground by 1000 # electrostatic sand alumina water resistant abrasive belt. The machined surface topography was observed by SEM, which showed that the microgroove arrays were uniform. The contact angles of the water on the microgroove arrays were measured in different directions. In the parallel direction, the contact angle of microgroove arrays is 142±0·5°, whereas in the vertical direction, it arrives 160±0·6°. The above values of contact angle mean that a stable superhydrophobic metallic surface was prepared by the micromilling and grinding.

Nanosecond Laser-Induced Underwater Superoleophobic and Underoil Superhydrophobic Mesh for Oil/Water Separation

Materials with special wettability have drawn considerable attention especially in the practical application for the separation and recovery of the oily wastewater, whereas there still remain challenges of the high-cost materials, significant time, and complicated production equipment. Here, a simple method to fabricate the underwater superoleophobic and underoil superhydrophobic brass mesh via the nanosecond laser ablation is reported for the first time, which provided the micro-/nanoscale hierarchical structures. This mesh is superhydrophilic and superoleophilic in air but superoleophobic under water and superhydrophobic under oil. On the basis of the special wettability of the as-fabricated mesh, we demonstrate a proof of the light or heavy oil/water separation, and the excellent separation efficiencies (>96%) and the superior water/oil breakthrough pressure coupled with the high water/oil flux are achieved. Moreover, the nanosecond laser technique is simple and economical, and it is advisable for the large-area and mass fabrication of the underwater superoleophobic and underoil superhydrophobic mesh in the large-scale oil/water separation.

Research on the post-processing method for CNC program oriented to miniature five-axis machining system

In this paper, an approach of converting the APT file generated by the CAM software to the CNC machining program, executed by the CNC system based on the UMAC control platform for the self-developed 5-axis micro-milling system, is presented. The transformation of the cutter location coordinate between workpiece coordinate system and machine coordinate system during processing is obtained by analyzing the motion topological structure of the micro-milling system. And the flow of writing the CNC program is also proposed according to the features of the CNC system. Then, the conversion of APT file to UMAC file is established and the auto-generation of the CNC milling program is realized through using the text processing functions in Matlab and the display of the tool-path is also realized by Matlabs functions.

Study on hardness and tribological properties of high-speed wire electrical discharge machining surface

The recast and the carbon layers were fabricated on AZ91D Magnesium (Mg) alloy surface by the high-speed wire electrical discharge machining (WEDM-HS) technology with various working parameters. The mechanical properties and friction behaviors of the layers were investigated by RETC micro-friction, wear tester and Agilent Technologies G200 nano indentation instruments. Results show that compared with the substrate, WEDM-HS samples with double-layer structure exhibited superior excellent mechanical properties and tribological performance. The hardness of recast layer was improved. And this method can enhance durability of AZ91D Mg alloy effectively.

High voltage transmission lines remote distance inspection system

In order to meet the demand of automation in high voltage transmission lines inspection and improve its precision, a remote distance inspection system is developed which is based on laser ranging and image processing technology. This system is used to detect the secure distance between transmission lines and object below it and scale of objects. Remote distance inspection system includes upper position computer and lower position machine. The lower position machine consisted of high revolution camera, two laser rangers, digital compass and GPS, these devices sent images, distance, attitude and location information to upper position computer. Measurement formulas derived from imaging principle. Upper position computer completes image process, measurement and other information management automatically. System structure is designed with light weight feature and total mass is 4kg, it is available on vehicle and unmanned aerial vehicle. System control software is developed with C++ language, inspection image and datum are recorded for the automated management. The system have been tested over a distance of 52m, 89m and 132m from objects, results show that the percent relative error is +1.9%, -2.2%, +2.9%, respectively. The high accuracy performance of this system is proved.

Tool wear inspection method for small lathe

This paper represents the method for tool wear area inspection for small lathe. Based on the machine vision technology, combined with the features of the cutting tool, tool wear area inspection system is designed. Facet model is used for Sub-pixel extraction of tool edge, then the main and minor cutting edge is fitted, and the wear area of tool tip zone is calculated. Tool wear experiments are done with PCD tool and #45 steel. Results show the tool wear inspection method could calculate the tool tip angle and the wear area of the tool tip precisely and rapidly. This method could monitor the tool wear in the cutting process for the small lathe.

Research on surface defect inspection for small magnetic rings

Surface defect characters of the small magnetic ring is diversiform and the diameter of surface defect is usually about 0.1mm, thus the magnetic ring existing defects used in industrial production is great security risks. However, currently the disadvantages of artificial visual method are cost high, efficiency low and etc. Therefore, a new method is needed to detect small magnetic ring automatically. In this paper, the design of the automatic inspection system is illustrated, the modified BHPF filter is used for de-noising and eventually the defect is located and recognized.

Research on Homogenization and Surface Integrity of Ti-6Al-4V Alloy by Longitudinal-Torsional Coupled Ultrasonic Vibration Ball-End Milling

This paper aims to study the surface homogenization and integrity of Ti-6Al4V alloy by longitudinal-torsional coupled ultrasonic vibration assisted ball-end milling. A method of continuous processing between the flat surface and freeform surface connection is proposed by using ultrasonic vibration assisted ball-end precision milling, during this process, it is not necessary to exchange the cutting tool. The way has been explored for changing the homogenization of surface on Ti-6Al-4V by ultrasonic vibration-assisted milling (UVAM). Cutting experiments employing three parameters, cutting speed, feed rate and depth of cut and two types of machining forms using ballend milling with UVAM and conventional milling (CM) respectively. The high frequency cutting force, finished surface roughness, topography and residual stresses on the surface and tool wear have been measured by advanced instruments. Particularly, adopting the high frequency cutting force measurement system, it is concluded cutting force in ball-end milling decreased significantly using UVAM as against CM. Moreover, the surface roughness by UVAM with ball-end milling is much better than the CM at a high cutting speed. However, an opposite trend is observed at a low cutting speed. Especially, there is a steep decrease from Ra 0.828 μm average value at 4000 rpm to Ra 0.129 μm average value at 5000 rpm. At the same time, the homogenization of surface roughness and residual stresses decrease significantly in UVAM as compared to which in CM when taking the transversal-longitudinal ratio into consideration. Cutting experiments and measuring results are demonstrated the validity and feasibility of UVAM with ball-end milling, and this method enjoys significant advantages compared to CM process.

The reference plane by BEMD for 3D roughness evaluation of micromilling surface

Surface roughness evaluation of a micro-milling surface using a 3D method can compensate for the deficiencies of the traditional 2D evaluation method, and improve the consistency and unity of the surface topography analysis. In order to obtain the reference plane for 3D roughness evaluation of a micro-milling surface, this study investigated the use of a bidimensional empirical mode decomposition algorithm (BEMD) to process the original surface data, and then use the frequency and energy information obtained by the data decomposition to determine the threshold for the evaluation criterion method. The simulation results showed that the method can effectively extract the reference plane, so that this approach can be extended to the evaluation of other machined surfaces.

A study on the micro machining characteristics in micro cutting of polycrystalline metals

In this study, experiments are carried out to evaluate the characteristics of micro cutting of polycrystalline metals material using a high speed machine tool with cubic boron nitride (CBN) tool inserts. The cutting forces were measured using a three-component dynamometer, the machined workpiece surfaces and the chip formation were examined using a scanning electron microscope (SEM). Experimental results indicate that Depth of cut and feed rate almost have significant effect on the main-cutting-force. The SEM observations on the machined surfaces and chip indicates that a significant ductile tearing and plowing phenomenon in the machined surface and chip.