Advanced Materials Research Vols. 189-193

Abstract: A new method of determining the coefficient of friction (COF) in expansion zone of tube hydroforming (THF) is proposed. The measuring method features that a round tube is hydro-formed into a square one by a radial compression accompanying a constant internal hydraulic pressure p, and the difference ΔL of the two diagonal lengths of the square section of deformed tube is taken as measuring index for COF. The relationships between the ΔL and the p, COF, relative displacement S/S0 of moving punches are established by the finite element (FE) simulation of the forming process. The COF can be determined by matching the indexes ΔL from experiments and simulation. The FE simulation results show that the measuring index ΔL is in exponent proportion to COF and the internal pressure p, it is extremely sensitive to the friction force or COF and conveniently measured and especially under a higher internal pressure.

Abstract: In this paper, we introduce a new test method for friction performance of wind turbine pitch bearing. Four loading devices are used to put on load on the pitch bearing from different directions through load board. It can accurately simulate the axial force, radial force and overturning moment of wind turbine pitch bearing. The data acquisition device can measure the value of speed, torque and actual output load of loading hydraulic cylinder. After analysis and calculation, the influence of additional friction torque produced by loading device can be obviated, the friction torque of wind turbine pitch bearing under different loads can be test accurately in the laboratory. The research shows that the structure of test bed is compact, mechanical rigidity is good, the replacement of bearing model is expedient. It puts on load easily and can measure the frictional torque of wind turbine pitch bearing under different loads more accurately. It can provide data for performance analysis of wind turbine pitch bearing and ensure the pitch bearing satisfying the application requirements.

Abstract: The paper focuses on the research of using the coupled thermo mechanical analysis method of rigid viscoplastic finite element and the evolution of dynamic recrystallization to establish the calculation model coupling factors of deformation, heat conduction, dynamic recrystallization in the DEFORM, and on the hot-forging simulation of AISI4140. Through the simulation, it makes a valid prediction of dynamic recrystallization volume fraction and the grain size of recrystallized during the metal hot-forging process.

Abstract: It is widely known that the continuous extrusion forming (CONFORM) process can produce ultra-long seamless products of various cross-sections for aluminum, copper and their alloys. In this paper, the continuous extrusion of AZ31 magnesium alloy is achieved. The effect of extrusion wheel velocity on microstructure of extrusions is investigated. The results indicate that grain refinement is realized during CONFORM process. As the extrusion wheel velocity increases, the grain size at the center of a cross section perpendicular to the extrusion direction of an extrusion increases, and the grain structure tends to become uniform in the surface region.

Abstract: Struvite (MgNH4PO4∙6H2O) is an insoluble double salt. It can precipitate in places such as pipes, aerators and pumps, which could lead to substantial problems influencing the normal operation of wastewater treatment equipments. At present, removal of ammonium nitrogen from various wastewaters by the formation of struvite has been widely investigated. This paper reviewed the research and application efforts concerning the treatment of ammonium nitrogen by struvite precipitation, which were obtained at home and abroad in recent years. The mechanism and influence factors of struvite precipitation for ammonium nitrogen removal were discussed. Additionally, the problems that still should be resolved and the research directions in future were pointed out.

Abstract: Mining from the equipment/technology process historical data can find diagnosis knowledge. Real-time analysis and evaluation on the status of equipment can be realized based on its current state parameters and historical information, which detect the potential fault rapidly and protect equipment to avoid failures further. This paper did an in-depth study in real-time data-based fault diagnosis system, built a real-time data integration platform and accomplished intelligent diagnosis method by ANFIS networks with the mined historical data. The production process was diagnosed and evaluated online with this diagnosis method. Combined with actual production system, its prototype system was developed.

Abstract: High-speed sheet metal stamping is popular because it is economical and quick means of producing intricate, accurate and durable components in large quantities. Scrap jumping up is one problem which usually occurs in high-speed stamping manufacturing processes. In this paper, the relevant factors are analyzed and studied such as the press tool, the shape and size of the stamping pieces, the structure and rigidity of pressing die, the clearance between punch and die, material properties of the blank, etc. Then ten cases are summarized that lead to scrap jumping up. For each case, corresponding solution is presented to avoid the scrap jumping up.

Abstract: Paper analyzed diagnosis technologies that were applied to manufacturing equipment, and researched the unidirectional mesh data structure of the fault essence. Then the integrated diagnosis method was proposed. The method was based on structure-fault tree, which has a good capability in knowledge management and maintenance. Diagnosis knowledge representation and organization model was expatiated, at same time the integrated reasoning process was accomplished. Finally, a prototype system for the CNC machine was developed that has verified the method’s correctness and feasibility.

Abstract: Forming conical parts is one of the complex and difficult fields in sheet metal forming processes; because of the low contact area of the sheet with the punch in the initial stages of forming, too much tension is applied to the sheet causing burst occurrence. Furthermore, since the major part of the sheet surface between the blank holder and punch tip is free, wrinkles appear on the wall of the drawn parts. Therefore, these parts are normally formed in the industry by spinning, explosive forming or multi-stage deep drawing processes. In this paper, the parameters in the process of hydroforming conical parts along with using finite element simulation and experimental procedures have been studied. The punch radiuses parameters (the punch tip radius and the radius between the conical and cylinder section and their effects on the bursting and thickness distribution were investigated.

Abstract: Super steel has the same chemical composition as plain carbon steel, but its yield strength is higher than plain carbon steel because it has finer grain size. The products of super steel sheet have been used in automobile parts, which not only improves the quality of the automobiles, but also reduces the cost and weight of automobiles, decreases energy consumption and environmental pollution. At present, several automobile manufacturers have applied the super steel products to their parts, such as Across Beam and Longitude Beam, Automotive wheel, et al. This paper introduces the tensile test, cold bending test and metallographic examination for 500MPa grade super steel sheet that have been done. The hardening index, value of plastic strain ratio, yield strength, tensile strength, even percentage elongation and other mechanical performances have been studied. The press forming performance of 500MPa grade super steel has been analyzed too. It can be used for guidance of stamping production.