Search

In order to reduce the defects of investment casting and improve its casting quality, vibration technology and casting technology are combined effectively and the effect of vibration degree of freedom, frequency and amplitude on the filling ability of liquid metal are studied by means of EDEM-FLUENT solid liquid coupling visualization. With the use of orthogonal test method, the sensitivity of the particles towards each parameter index is obtained. Optimal vibration parameters are chosen and then the best variable cell vibration casting solution is obtained.

To meet the need of modernized coal dressing, topology theory was used to build a kind of hybrid mechanism 2PRRR-R which can work as a main excitation mechanism of three freedom degree hybrid vibration screen with two-translation and one-rotation. Next, D′Alembert’s principle was introduced to establish a kinetic model of vibration screen frame and surface, and kinematic equations of directions of vibration screen frame and surface was achieved. Then, ADAMS was used to perform kinetic simulation of vibration screen, and kinetic parameters of the hybrid vibration screen was finally tested on multi-dimensional vibration screening test bench. The research shows that kinetic parameters’ numerical simulation of hybrid vibration screen with two-translation and one-rotation basically agrees with spot test value, which verifies the feasibility of the mechanism design, that the screen frame is of two motion freedom, that screen surface is of three motion freedom degree, that the rotation of the screen surface is relatively independent and controllable. The research provides further study of kinetic properties and development of hybrid vibration screen with two-translation and one-rotation with workable reference.

To analyze liquid metal flow in mold under multidimensional vibration condition, discrete element method (DEM) is taken to approximately stimulate liquid metal flow and to simulate numerically liquid metal flow filling process in casting technique under multidimensional vibration. The orthogonal experiment design is taken to study vibration dimension, frequency as well as amplitude influence on liquid metal filling capacity; Through EDEM platform, numerical simulation research in each test scheme can be carried out to get influence of filling time upon sensitivity degree of each parameter index so as to select the optimal test scheme. Casting experiment results in the self-made solidification test-bed under multidimensional vibration match the numerical simulation, showing that multidimensional vibration could significantly improve filling capacity of castings.

In order to reduce the false alarm rate in coal mine fire warning system, we apply information fusion technology to the system and propose a fire forecast algorithm based on Rough Set Support Vector Machine ( RS-SVM ). Firstly, we map the feature description of coal mine fires to the knowledge representation system described by rough set; Secondly, we discrete the continuous attributes and eliminate the redundant information for attribute reduction to form a rule set of this knowledge representation system; At last, we use the above rule set as the training sample to optimize the parameters for the fire warning support vector machine. The experimental results show that the accuracy of the algorithm is very high. It can make timely and accurate prediction of coal mine fire.

In order to simplify the structure of switching valve groups and reduce the failure rate in the high pressure abrasive jet mixing system, a combined switch valve for the system has been designed. The combined switching valve can implement a motor to drive four spools for two open and two closed electric control switch of high pressure abrasive jet mixing system, which has the advantages of compact structure, small space occupation, convenient control and high reliability.

At present, pulley produced in China has been able to meet the demand of domestic and international markets. But there are many problem of the pulley industry in our country, such as too many production enterprises and the low level of export products. And as components of drive system are light weight and raw material price of pulley casting are rising, manufacturing requirements of the pulley are also more and more high. Aiming at the casting defects of pulley that enterprise current product, pulley casting blank model of common material HT250 be made by three-dimension software, numerical simulation of filling and solidification process for pulley sand casting by the casting simulation software Procast, the size and location of the various casting defects were forecasted and analyzed, reflecting the pulley filling and solidification process of the actual situation, due to the thicker pulley rim and less heat dissipation, position of shrinkage is close to the middle of rim [, a method of eliminating defects is proposed to realize sequential solidification, and thus to minimize porosity shrinkage and improve casting performance and reduce casting time and reduce production costs.

Using three-dimensional discrete element method (DEM) to simulate the vibration of the evaporated pattern casting molding process, accordingly summary the influence law of vibration direction effecting on dry sand filling. The results show that the 3DOF vibration filling effect is best, 2DOF takes second place, 1DOF is the worst. In the 2DOF vibration the YZ direction is best, XY direction worst. Meanwhile Y direction vibration works best in 1DOF vibration, second is X direction, and Z direction gets worst.

In order to reduce casting defects and improve casting quality, the author has developed a three-dimensional parallel vibration casting machine based on parallel mechanism. The paper introduces the three-dimensional parallel vibration casting machine in structure composition and functional properties, the casting machine degree of freedom of excitation mechanism is calculated, its motion performance is analyzed, and the kinematics equations are established. The designed casting machine achieves support and excitation functional separation of moving parts which takes complete decoupling of hybrid mechanism 2PRRR-P (2R ) as excitation mechanism, realizing flask vibration along the X, Y, Z three directions. Test results show that, the casting machine can significantly improve casting quality, raise labor productivity, save casting raw materials, and reduce the production costs.

On the requirement of the obstacle negotiating robot in unstructured environment, a new type attitude-adjusting track mobile robot adapting to unstructured environment has been presented. This paper introduced the structure of the autonomous obstacle negotiating robot, the robot motion characteristics under typical terrain, and the side tumbling attitude-adjusting and automatic reset. This kind of mobile robot has the characteristics of simple structure and practical operation and has strong ability of environment adaption and obstacle negotiating walking.

Basing on the basic principle of the mechanical movement, the movement and dynamic performance analysis of Opposed Reciprocating Ten-Plunger Pump are done. The equations about position, velocity and acceleration of the 10 plungers are deduced. The motion characteristics of each plunger are calculated. Thus, the calculation model of the equivalent resistance torque of the-plunger is simplified. The drag torques on the crankshaft is gotten. So the equivalent torque and equivalent power on the crankshaft are analyzed. At the same time, the efficiency of the selected motor is analyzed in order to achieve good power save control.