Hai Guang Zhang

Study on Processing and Model Building of Composite Structure Forming for 3-D Regenerative Bone Scaffold

Based on the analyzing for strengths and weaknesses of the rapid prototyping (RP) and electrospinning technique in the manufacturing of three-dimensional bone scaffold, the defects including RP’s low precision and electrospinning’ low intensity has been found. Accordingly, composite structure forming (CSF) has been proposed. This approach integrates the advantage of rapid prototyping and electrospinning. Furthermore, the modeling method of Scaffold for composition forming has been proposed .At the end, the method of controlling process has been given.

Bubble Image Processing Algorithm and Application in Vacuum Casting Equipment

Bubbles in the manufacturing process are common. The bubbles often lead to the decrease of the product’s surface quality and internal performance. This paper summarized the published researches and applications of the detection and processing for bubble images, of which the advantages and disadvantages were also presented. Based on the above mentioned results, this paper then proposed a new bubble image processing algorithm for vacuum casting process, in which the characteristics of the bubbles in vacuum casting process and the problems possibly caused in detail were analyzed. According to the characteristics of bubbles in vacuum casting process, an image processing algorithms was designed using Matlab. The simulation result showed the efficiency of the proposed algorithm.

Studying on Auxiliary Gradient Rings for the Collecting Area of Electrospinning

When electrospinning has been used as a special technology of regenerative bone scaffold, for raising the efficiency of electrospinning and decreasing collecting area, the mechanism of bending instability was analyzed and concluded that the force of electric field is a key factor. Auxiliary gradient rings have been added to electric field, which changed the environment of electric filed. Then, it was verified that additive gradient rings could reduce the collecting area. On the other hand, Maxwell was used to analyze the strength and structure of electric field. The maximum intensity of electric field existed in the position of nozzle. The farther apart from nozzle, the rapidly intensity decreased. When auxiliary gradient rings had been added, the intensity of instability stage showed increased trend. Mechanism analysis and experimental result were confirmed by the simulation effectively.

Process Parameter Prediction of Differential Pressure Vacuum Casting Based on Support Vector Machine

To reduce warpage deformation of the differential pressure vacuum casting (DPVC) products and to improve product quality, One prediction method for process parameters based on support vector machine (SVM) and artificial fish-swarm algorithm (AFSA) is proposed.Firstly sample test data is abtained by using orthogonal experimental design and numerical simulation to construct models to forecast warpage of DPVC product based on SVM. Simultaneously to improve the predictive accuracy of the model, AFSA is introduced to optimize the SVM model. And then using this model recommends and adjusts the DPVC process in order to achieve quality control. Finally , through the analysis of a mouse shell , the validity of the method proposed is verified, providing a feasible method for DPVC product quality control

Fuzzy Self-Tuning PID Controller for Pressure Control in VCM

Owing to nonlinearity, time-delay and complexity of pressure control system in vacuum casting (VC) process, the traditional pressure tuning method can’t guarantee the good performance and thus high quality product nowadays. In this paper, a novel pressure control strategy for vacuum casting process, combining fuzzy PID and neural network methods, is proposed to solve this problem. The proposed strategy can on-line regulate pressure difference between low and upper chambers of VCM to meet the pressure requirement in VC process, thus ensuring high quality part. With the aid of Matlab and configuration software – Forcecontrol, the proposed fuzzy self-tuning controller is implemented in a sample machine. The experiment result shows that the presented pressure controller can track the pressure profile accurately and thus can further improve the product quality.

ABAQUS-Based Numerical Computation and Experiment Research on Silicon Rubber Mould’s Deformation during DPVC Process

Aiming at exploiting the impact of filling rate and pressure difference on thin-wall product during filling stage of differential pressure vacuum casting (DPVC) process and based on Yeoh model, a finite element mathematical structure model of silicon rubber is proposed. Employing nonlinear Finite Element Method (FEM), the impact of soft moulds deformation on products dimensional precision during different pressure difference is studied. Finally, the experiment carried out on a sample machine verifies that the solution of established finite element mathematical structure model of silicon rubber is very close to experiment result and thus provides an effective method for optimizing the pressure difference and mould optimized design.

The Research on Two-Component Materials Mixed Method for Vacuum Casting

To solve vacuum casting process exist two-component polyurethane difficult to uniform mixing problems. A non-symmetric eccentric large blade agitator was proposed and the speed was period changed to strengthen the mixed effects. A fluid dynamics of variable speed agitator tank was proposed to numerical simulation flow behacior with Euler - Euler two-fluid model and the dynamic mesh (SM) method. Though numerical simulate to study flow field characteristics of variable speed agitator tank.. The experiment results show that the proposed method can not only achieve high viscosity polyurethane resin with uniform mixing, and shorten the processing time. Effectively solve the polyurethane resin materials difficult to uniform mixing problems.

The Optimization of Vacuum Casting Filling Velocity Based on Numerical Simulation

In the process of vacuum casting, non-uniform flow front velocity about pouring material will lead to casting non-uniform shrinkage and warping deformation. Ideal filling pattern should make pouring material fill into the mold cavity with uniform flow front velocity. Give an optimization method of vacuum casting process, optimize the filling velocity in the filling process by combining numerical simulation and optimization method, and make the flow front velocity of pouring material uniform in the filling process, further reduce the warping deformation of casting. The example shows that the optimal model and the given solution algorithm is feasible.

Hybrid Intelligence Process Parameters Setting and Optimization on Differential Pressure Vacuum Casting

Considering that the problem of traditional process parameters setting in vacuum casting machine is of long period, high cost and inferior quality stability, a kind of hybrid intelligent decision model which combined with case-based reasoning, neural network and fuzzy reasoning were established. First, use the case-based reasoning technology to extract the similar case from the case database. Then, use the initial parameters to run the mould trial. Finally, use the fuzzy reasoning technology to optimize the initial parameters according to the product defects. Based on the above-mentioned intelligence model, the related hardware and software system was established. The actual practice proved that the system is effective and can be used in practical production.

Study on Regulated Pressure Vacuum Casting Method for Larger & Thin-Wall Castings

Aiming at the problem that current vacuum casting method lack of the filling ability in filling large & thin-wall castings. Therefore, a regulated pressure vacuum casting method is proposed, which using regulated pressure to improve the filling ability. The process and mechanism for regulated pressure vacuum casting method is presented and proved it through the home-made V450N-VD vacuum casting prototype. The results show that the regulated pressure vacuum casting method has higher filling capacity and can provide higher negative pressure during the whole filling process. So regulated pressure vacuum casting method has profound development potential.