Sheng Dun Zhao

A Novel Dimension Measurement System of Hot Large Open Die Forgings

In this paper, based on the analysis of the problem about manual measure for hot large open die forings and the significance for realizing noncontact online measure, a novel dimension measurement system of hot large open die forgings is presented. Laser ranging method is used for measuring axial dimension and binocular vision method is used for measuring radial dimension, so that the system characterized by large size, automated, fast response and high precision which benefits high efficiency and low material loss in open die forging process.

Research on Clinching with AC Servo Direct-Drive Device

The purpose of this paper is to develop clinching technology using AC servo direct-drive device. The control systems of AC servo direct-drive device are designed to control the clinching. It could accurately control the connection of aluminum alloy 6061 sheets with the round joint. The joint quality is evaluated by the tensile tests. The results of the tensile tests shown that fracture load satisfied the required joint strength. Meanwhile, AC servo direct-drive device also could ensure the efficiency and quality of clinching process.

Experiment Study on Novel Precision Cropping Machinery Using Rotary Striking Action

This paper illuminates a new type of precision cropping process method with rotary striking action. The new process makes use of a controllable circumferential strike on a metal bar with a V-shaped notch. The working principle of the machine is described. Different types of metal bars have been tested, and both bad results and successful results were stated in the paper. The most ideal control mode has been obtained. The experimental results show that the new cropping process can crop bars with different materials and diameters. In some cases, it can be directly used in the subsequent industrial production.

Completely Inelastic Collision to Confirm Maximum Punch Pressure Force of Cold Pressure Welding

The maximum punch pressure force (TMPPF) of cold welding pressure affects not only the performance of the welding bonding but also the amount of the area of welding bonding. If punch force is more bigger, it may be take place cracks, stress concentration and welding concave pits, which affect application of materials and increase incidence of faults. The process that punch pressure of cold welding pressure applied on sheet materials to attain welding bonding is simplified beam in cold pressure welding. Under normal circumstances it is an important method to TMPPF by the manner of experiment, but the method to attain TMPPF is limited. In the paper completely inelastic collision theory is applied to explain the process of cold welding pressure, the theory of completely inelastic collision offers principle theory to attain TMPPF. In this paper, two supposes are put forward, on the basis of two supposes the critical velocity is attained. At the same time, critical kinetic momentum or critical kinetic energy will be attained. On the basis of the law of conservation of energy, energy balance equation is attained, which will drop in calculating difficulty of the non-linear process of cold pressure welding and decrease calculated amount. In this paper on the basis of the process of collision all phases are analyzed. Indeed elastic-plastic deformation phase is completely inelastic collision phase, and from point of view of collision to calculate energy loss. At the same time, to suppose other plate is utter stiff can attain critical velocity, thus, to achieve the equation of TMPPF.

Numerical and Experimental Studies on Aerodynamic Characteristics of Pneumatic Exhaust with Perforated Panel Muffler

The expansion chamber mufflers compounding with the perforated panels are commonly used in the suppression of intermittent exhaust noise (IEN) generated by the exhaust air from the cylinder and ducts of pneumatic devices. The flow resistance and noise reduction performances of IEN are both important. A simplified aerodynamic model is presented to study the flow characteristics in the pneumatic cylinder and chambers of the muffler with perforated panels. The relationship between pressure and mass flow rate is established in the transient exhaust process. Validation experiments measuring the cylinder pressure and exhaust noise of the pneumatic friction clutch and brake (PFC/B) exhaust system installed a three-level perforated panel muffler which can be separated show that the calculated results are very close to that of the actual exhaust process.

Numerical Simulation on Thixocasting Process of Auto Box-Like

Semi-solid metal processing (thixoforming) is a potential forming technology, which can realize near-net-shape forming process with good quality in one forming step. In this study, semi-solid casting (thixocasting) was used to form the auto box-like. Based on Power Law Cut-Off (PLCO) model and finite element code Procast software, the thixocasting process was modeled and simulated. The impact of main process parameters such as initial billet temperature, ram speed as well as die temperature on the thixocasting process was studied. The results show that thixocasting process can be used in forming auto box-like.

Parameters Optimization of Semisolid Diecasting Process for Air-Conditioner’s Triple Valve in HPb59-1 Alloy

The disadvantages of air-conditioner’s triple valve in HPb59-1 alloy processed by traditional solid state hot forging, such as larger forming loads, lower material utilization, larger subsequent machining allowance, nonuniform microstructure, are put forward. However, semisolid diecasting forming which can overcome the above shortcomings is a fascinating technology. The process paremeters which had a larger influence on filling ability of semisolid slurry and casting quality, such as pouring temperature, shot velocity and preheated temperature of the die, were chosen. Furthermore, based on orthogonal test, the semisolid diecasting process of a certain type triple valve was simulated with FLOW-3D. According to the analysis of temperature field, pressure field and surface defect concentration, the optimal process parameters such as pouring temperature 897.25 °C, shot velocity 1.5 m/s and preheated temperature of the die 260 °C, were obtained, and the effectiveness of the technology was well demonstrated by numerical simulation.

Numerical Simulation of Double Rollers Clamping Spinning Process for Flanging

Double rollers clamping spinning (DRCS) is a new process to form thin-walled rotary shell parts with complex flange, which adopts two rollers to clamp the workpiece in the forming. Using FE simulation code ABAQUS/Explicit, the 3D simulation model of DRCS process for flanging is established, and the whole DRCS process and material deformation have been simulated. Distribution of equivalent stress, equivalent strain and wall thickness of flange in the DRCS process are obtained. And then, the effects of roller feed rate and flange length on the formed flange part are studied. Results show that equivalent stress, equivalent strain and reduction in wall thickness increase with the decrease of roller feed rate, while increase with the increase of flange length. The results obtained in this paper can provide the references to determine and optimize the new spinning process parameters.

Application of Radial Forging and Remelting Treatment to Prepare Semi-Solid Billet of AlMg0.7Si Alloy

Semi-solid AlMg0.7Si alloy was prepared by recrystallization and partial melting (RAP) method which including radial forging (RF) and remelting process. RF was carried out with different area reduction ratios (ARRs) to accumulate strains, effect of ARR and remelting time on microstructure was studied, mechanism of RAP preparing semi-solid AlMg0.7Si alloy was summarized. Results show that, compared with the large and irregular solid grains form remelting of starting material, solid grains of semi-solid alloy prepared by RAP are fine and globular, and the optimum microstructure can be obtained when alloy with 80% ARR is remelted at 630 °C for 10 min. With the increase of ARR, the solid grains are smaller and rounder. With the increase of remelting time, the average grain size is increased, and the spheroidization degree of solid grain is gradually improved. The main mechanism consists of pre-deformation, recovery and recrystallization, grains fragmentation, grains spheroidization and coarsening.

3D Numerical and Experimental Investigation on Semi-Solid AlSi9Mg Alloy Slurry Prepared by Electromagnetic Stirring

To prepare semi-solid AlSi9Mg alloy slurry, we simulated electromagnetic stirring (EMS) based on a coupled 3D model of electromagnetic field, temperature field, and flow field by sequentially coupling ANSOFT and FLUENT software. Results show that magnetic flux density and electromagnetic body force (EMF) decrease and exhibit non-uniform patterns as stirring frequency increases. However, magnetic flux density and EMF increase in proportion to the stirring current but become more inhomogeneous. As EMF increases, the flow velocity and the depth of vortex in the semi-solid slurry gradually increase; thus, slurry temperature decreases. The deviation in temperature is then reduced between the center and the edge. As a result, the microstructure of the slurry evolves from coarse rosette grains to fine and spheroidal ones. By comparison, turbulent flow is generated by excessive and more unevenly distributed EMF, which causes deterioration in microstructures, such as the formation of cavities in the semi-solid AlSi9Mg alloy slurry. Based on simulation and experimental results, our conclusion is that reasonable process parameters have been obtained and verified experimentally. These results also show the validity and reliability of EMS-prepared semi-solid AlSi9Mg alloy.