Advanced Materials Research Vols. 472-475

Abstract: An experimental method was developed to study the adherence properties of the oxide scale formed on microalloyed low carbon steel after hot strip rolling. The evolution of the oxide scale during laminar cooling was investigated using Gleeble 3500 Thermal-Mechanical Simulator connected with a humid air generator. After the sample cooled down to ambient temperature, the oxide scale was protected by lacquer to prevent the scale from losing. Physicochemical characteristics of the oxide scale were examined and the adherence mechanism was discussed. Decomposed wustite a mixture of α-iron and magnetite (Fe₃O₄), can substantially improve the integrity of oxide scale. However, large quantities of hematite (Fe₂O₃) or retained wustite (FeO) were found detrimental to the adhesion of the oxide scale. It is found that the adherence of oxide scales significantly depends on the phase composition of oxide scales with different thickness.

Abstract: Considering the nonlinear characteristic of ball screw, a Duffing equation with damping is used to model the nonlinear dynamics of feed system by employing the elastic displacement method. Then by using the tools of phase trajectory map, Poincare section and bifurcation diagram respectively, structure of the proposed model is identified, meanwhile, the properties of bifurcation and chaos are judged. Numerical results show that as the feed system works, the screw nonlinear vibrates. Therefore, the dynamics response of the system cannot be described by a linear dynamics model. In other words, a nonlinear dynamics model must be employed to analyze the dynamic properties of the system. The proposed model has an advantage over the model characterized by a linear dynamics with multiple degrees since the latter is only applied to the system with high stiffness. In addition, the dynamics properties of the feed system are revealed as the stiffness is low or the support at both ends in varied. A test in a NC machine tool verified the validity of the analytic results.

Abstract: The non-linear and time-varying natures of the process together with the large disturbances of several types are the key challenge for the control design. A controller based on multi- resolution decomposition using wavelets is presented in the paper. The wavelet is used to decompose the error signal into signals at different scales.These signals are then used to compensate for the uncertainties in the plant.The controller is similar to proportional integral derivative controller in principle and application. the output from this control system represents the cumulative effect of uncertainties such as measurement noise, frictional variations and external torque disturbances which manifest at different scales. This controller better solves the nonlinear and time-varying togetther with the great disturbance.

Abstract: The extremely poor sewage quality could make the sewage heat utilization difficult. The paper introduces the content and distribution property of the sewage dirt. For the dirt properties and project experience, it proposes the two basic points of the anti-blocking technique in sewage source heat pump system: filtering surface continuous regeneration and dirt continuous reduction and the request for filtering pore size parameters. It also describes the principle of filtering surface hydraulic continuous regenerative technique and establishes its mathematical model and design method of the device. The calculation and application result indicates that filtering surface hydraulic continuous regenerative technique can guarantee the filtering effect and operation flow stable.

Abstract: Bridge Fabricating System is one of the most widely used large-scale machinery equipment in construction fields like highway, railway both at home and abroad. Through structural analysis on the bridge fabricating system, and build a finite element model with ANSYS, we can form a found- ation for Static Analysis for it.

Abstract: On the basses of analyzing the defects of variable blank holder force hydraulic press on construction and its rigid being not enough,the realization of designing method,working principle,hydraulic and system for ne controlling w type upper multi-point deep drawing with variable blank—holding force controlled by computer was introduced.In order to verify the effect of application of this set up,the testing results of deep drawing a rectangular box and a cylindrical cup formed component was presented. The results show that the equipment has low cost, general in using and optimal efficient of controlling.

Abstract: This paper researched the mechanism and model of moisture transfer in the core material of VIP- glass fiber, and introduced the vacuum drying technology to enhance the gas molecules’ movement under vacuum, accelerate the speed of water vaporization and avoid voids adhesion to overcome the adsorption resistance. The article also designed the equipment to provide experimental possibilities for the theoretical study.

Abstract: Over the past decades, many kinds of double-sided pressure forming processes have been proposed to improve the formability of lightweight materials which exhibit distinctly poor forming capability. In the present study, the effects of double-sided pressure on the deformation behavior of AA5052-O aluminum alloy sheet metal under tension-compression deformation state are studied numerically using the finite element method based on the Gurson damage model. It is demonstrated that superimposed double-sided pressure significantly increases the left-side of the forming limit diagram and the formability increase value is sensitive to the strain path.

Abstract: This paper presents a rack-and-pinion pumping unit. A type of SRD (switched reluctance driver) motor is utilized as the driving unit of the pumping unit. The rotation direction of the output shaft of the motor can change automatically, without reversing mechanism，so it can directly dive the gear box and then drive the rack-and-pinion in which the rack connected with the suck rod. Additionally, a super capacitor unit and control unit of charge and discharge is used to design the balance of the pumping unit. Due to the special balance design and no crank-rocker mechanism in the rack-and-pinion pumping unit, it has features of simple structure, less floor area, well balanced and high running efficiency. The most important is that the stroke and number of punching can be adjusted in a wide range which can adapt to different oil wells.

Abstract: In sheet metal forming, the friction between tooling and workpiece is an important factor which affects not only the quality of products but also the service life of tooling. In order to consider the effects of friction accurately for the optimization of stamping process and simulation, the friction behavior under different forming speed was investigated via tensile strip experiments. A 10000N servo-press which forming speed is ranged from 0.1mm/s to 200mm/s was used to collect the experiment data. Based on these data, the law of friction between tooling and workpiece was derived, it will be very useful to help set up the displacement-force and forming speed curve for the optimization of stamping process when a servo-press is employed.