Applied Mechanics and Materials Vols. 229-231

Abstract: The harmonic gear cold rolling process is an effective method to solve mass production. However, tooth profile quality problems greatly hinder the development of the process. Based on engagement theory, the dynamic characteristics of the rolling process and flexible wheel rolling tooth profile errors caused by the changes of the number of contact points were analyzed and studied, and the process methods were put forward to eliminate or reduce tooth profile errors in this paper, which has an important significance in analysis of rolling tooth profile errors, modification shape of the rolling wheel, optimization of process parameters and improvement of gear rolling quality.

Abstract: According to the alternation of the exterior situation of adhering sand casing, the exterior asperity should be developed, and the fluid drag force between the casing and the cement mantle should be increased, then the cementing strength and the cement job quality between interfaces could be increased. The cementing strength between the adhering sand casing and the interface of cement mantle is related to sand grain diameter, distribution density and the thickness of adhering sand agent, according to the results of in-house experiment, by using gray correlative analysis method the degree of association between the cementing strength and the preceding effects has been separately calculated to be 0.436, 0.246 and 0.318.

Abstract: Coal particles cleanout which is regarded as the key technology in the operation of coal bed methane (CBM) wells, play an important part in making steady production. In oil wells, Sand cleanout is operated by circulating a liquid or a multiphase fluid into the wellbore to bring sand particles to the surface. Although the sand cleanout operations have been applied successfully in most wells with high efficiency and negligible leakage, it would leak working fluid into coal bed formation, destroy the structure of coal bed and jam the formed channel of gas production. In this paper, a new continuous vacuum cleanout technology has been developed to effectively remove coal particles in CBM wells by employing a jet pump. The Concentric Tubing String (CTS) which is assembled by 3.5 inch tubing and 1.5 inch tubing is also introduced in, because there is no CCT technology in China at the moment. Detailed structure and principle of the coal particles cleanout technology system are described, while a theoretical model is formulated to optimally design the system based on the coal particles settling experimental data and jet pumping theory. It has been shown from field applications that the coal particles cleanout technology makes significant improvements in achieving high efficiency and preventing leakage in CBM wells. Moreover, the new technology reduces the skin damage and increase the production compared to non-vacuum CBM wells.

Abstract: This paper studies the influence of machine slideway precision on the overall accuracy of machine tools, and puts forward the root causes of the decline in accuracy of machine tool guide is rail wear, the decline of rail accuracy will impact on the adjacent unit cell, thus decline the accuracy of the machined parts; Finally takes floor-type milling & boring machine as research object, bases on geometric error models of the theory of multi-body system to describe the spindle box rail wear trends and establish relationship between the spindle box rail wear and the machine precision.

Abstract: In this paper, the tidal stream turbine blade is designed by using blade element momentum (BEM) theory. The bidirectional airfoil is created derived from NACA airfoil. Ansys-CFX is used to predict the hydrodynamic performance of this bidirectional airfoil, and it turns out that the bidirectional airfoil works well at both of the tidal current directions. A test turbine named rotor 2 is used, and a comparison is made between experimental results of the test turbine and numerical prediction results to prove the correctness of the numerical method. The power coefficient of bidirectional tidal stream turbine obtained by CFD method is 39.36% at the design tip speed ratio.

Abstract: This paper analyzed the disadvantages in current heating sink, which includes the waste of water and electric power, and hazardous elements to the staff. This paper proposed a new water and electricity separation energy-saving heating sink. This kind of heating sink could improve the water and electric power efficiency, as well as safety performance. The heating system of sink was improved by analyzing the electromagnetic heating method, the bottom structure of the sink, and the dirt discharge method.

Abstract: Focused on transformer silicon steel cutting line feeding drive system which is made of permanent magnet linear synchronous motor, this paper proposes and designs a new kind model about friction exists in the system, viz. within a little speed range the model prescribes a little static friction interval, in where speed is prescribed for zero. Not in this small speed range, it is prescribed for sliding friction interval. So that the model divides the whole sphere of action of the friction into two sections, then the paper discusses each part respectively, finds out the model parameters of each parts, basing on these, friction compensation is used to control the impact of friction on system performance. Afterwards, the paper uses recursive least squares (RLS) to estimate the total mass of mover and its load, and viscous friction coefficient, then the paper uses the estimated values to amend the corresponding parameters in the friction model, and improves the friction compensation effect. Finally, simulations were carried out, the results show the impact of various part on the system performance, and also prove the validity of the friction compensation in the transformer silicon steel cutting line feeding drive system, which is made up of permanent magnet linear synchronous motor.

Abstract: The microwave-induced hydrogen peroxide oxidation process was used for the treatment of synthetic imidacloprid pesticide wastewater, which the initial concentration of COD was 268mg/L. The results showed that COD removal rate could reach 50.06% with the following working conditions: imidacloprid pesticide wastewater 100mL, H2O2 concentration 26.52g/L, microwave power 119W, irradiation time 1min, pH value 6. It provides an effective technology for the removal of imidacloprid pesticide wastewater.

Abstract: At present, most studies on magnesium alloy sheet forming were carried under hydraulic press. In this paper, differential temperature forming of AZ31B magnesium alloy sheet under the J23-63 mechanical press were carried out. Through an orthogonal test about studying the influence of process parameters on AZ31B magnesium alloy sheet drawing, some conclusions were drawn, which are: the influence of drawing temperature on sheet forming is the biggest, then the drawing die clearance, and lubricant respectively; the optimal process parameters combination is drawing temperature of 310°C, 1.10t die clearance, and 8mm die radius in this test.

Abstract: The drawability of ME20 and ZE10 magnesium alloys sheets under mechanical press were investigated. The deep drawing experiment was tried out based on research production of AZ31 sheet forming. The forming temperature range of two sheets was obtained, and the ZE10 magnesium alloys sheets were formed well at lower temperature than ME20 alloy. The microstructures of ME20 consisted of fine grains and precipitates did not change evidently during the drawing process. The equiaxed grains of ZE10 included a great deal of twinning were refined obviously. The drawability was related with alloy compositions and grain size. The fractures were observed through SEM to probe the fracture mechanism of two sheets.