Advanced Materials Research Vols. 189-193

Abstract: The cold forging process of large module spur gear with four modules and 59mm breadth is performed by means of numerical simulation method. Two processes to forming such spur gears were compared by the simulation method, one is with the closed-die performing and extrusion in the finish-forging, the other is with divided-flow method in the finish-forging. Especially, the divided-flow method is analyzed in detail. The necessary reference and basis to realize practical cold precision forging process of spur gear with large modulus is provided eventually.

Abstract: For getting the higher quality,the paper analyses the punching order according to the part shape,then determines the die styles.The dies include blanking and bending steps,the bending dies are choosed carefully,from the part to its’extension size,then to cavity size and punch size,thus the general assembly drawing is tested whether it is right.

Abstract: For hot rolling of titanium alloy large rings, rolling force is very important for designing, choosing and optimizing of processing plan and rolling mill. In the paper, the average shape parameter of the deformation zone of ring rolling is presented first, and then a reliable coupled thermo-mechanical three-dimensional (3D) finite element (FE) model for the process is developed. Finally, influences of the blank outer radius R0 and inner radius r0 on rolling force are discussed and compared for exploring blank thickness effects. The main results show that decreasing the blank thickness by decreasing R0 or increasing r0 leads to a saving of rolling force, while R0 has a predominant effect than r0.

Abstract: For the bulging forming of sheet metal industry, two of the major disadvantages are large punch load and short bulging height, generally referring to the traditional process. In this present work, a new processing technique had been introduced for bulging forming based on bottom compression drawing method. The finite element method (FEM) with DEFORM-2D was used to investigate the bulging process. Besides, the mechanism of dimple defect occurred in bulging process was analysed with numerical simulation. The results showed that the dimple defect divided into four stages in the bulging process, where revealed an inverted cone-shape at the bottom part of the centre workpiece. Moreover, the laboratory experiments were carried out to validate the results of numerical simulation, which showed a good agreement with the FEM simulation results.

Abstract: The ordered nanochannel-array of anodic titanium oxide (ATO) is formed on the electro-polished titanium substrate. This reproducible procedure of long-range ordered nanochannel ATO retains 170 nm films in length. The process is deduced by electrochemically and thermodynamically; from high defect structure of porous ATO and small sizing of decomposing TiO₂ cluster on the surfaces. In this study, ATO with 68.2% porosity is discomposed at 581 °C under oxygen partial pressure of 4×10^-9 atm. The pore of ATO has wall thickness of 25 nm with density of 8×10⁹ per cm² under 1.2 vol.% hydrofluoric acid (HF) and 10 vol.% sulfuric acid (H₂SO₄) electrolyte for 90 seconds of 20 V of applied potential. The pore size is 100 nm in diameter and uniformly distributed with 120 nm pore-to pore distance in between.

Abstract: In order to diagnose the fault of the pump oil well, a fault diagnosis method based on the wavelet packet and the neural network is introduced. Firstly, the dynamometer card of the pumping well is gathered and normalized, then these data are decomposed by using three layers of wavelet packet. It makes up eight energy eigenvectors which are regarded as the input eigenvector of the RBF network. The experiment indicates that the method can not only detect the fault of the pumping oil well but also can recognize the fault type of it. It shows that the method is very effective for safety protection and fault diagnosis in the pumping oil well.

Abstract: Pilot cold rolling mill is the important tool for the cold rolling process researching and new steel grade development. According to the design of the new type direct pulling pilot cold rolling mill, based on the mass flow constant principle, strip exit thickness indirect measurement method is studied. During rolling, strip entry and exit speed can be calculated accurately according to the measured value of two sides’ clamps movement. Data filtering treatment is adopted and program flow chart is designed. Based on the material entry thickness measured manually, exit thickness of all passes can be measured indirectly. This thickness indirect measurement method has been applied successfully on the new type pilot cold rolling mill, and the measurement results show that this method has a good accuracy.

Abstract: Based on empirical analysis and FEA modeling of multi-stage sheet metal stamping, the optimal sheet metal stamping process can be supplied. Concurrently, the effects of process parameters on formability are found by numerical simulation. Taking an example of deep drawing part, the results got from the numerical simulation are compared with experimental results, which proves that finite element analysis (FEA) is effective and accurate in optimizing the process design of multi-stage sheet metal progressive stamping.

Abstract: Radial-axial ring rolling is a process widely used to produce large precise seamless rings. The regulation of rotation speeds between main roll and axial rolls and tangential slip between main roll and ring influence greatly the rolling process. In this paper, an equation governing regulation of rotation speeds is derived. Influences to rotation speeds from conic angle and contact position are analyzed. Equation of relative tangential slip speeds in both inner and outer diameters are established, which are employed to creat a condition of non tangential slip in radial-axial ring rolling process.

Abstract: To remove casting porosity and obtain smaller crystal grains, many large forgings need ingots to be upset axially with large ratio of height to diameter (H/D) greater than 3. But the ingots with large H/D are prone to buckling during upsetting process, and have non-uniform internal stress and strain distribution, cracks at barreling and other defects. A new axial upsetting process was proposed to handle these problems. Firstly, the research described deformation inhomogeneity and cracking tendency, and analyzed the causes of defects in the flat anvil upsetting process. Secondly, three two-stage upsetting processes were tried to improve the uneven deformation in the flat anvil upsetting, which applied symmetrical spherical convex die, conical convex die and multi-line sweeping concave die respectively in the first stage, and used flat anvils in the second stage. The effect of the die surfaces on constraining those defects was analyzed. Finally, three three-stage upsetting processes were suggested to take advantages of different die surfaces to stabilize the process. It was observed that the upsetting had better result from using conical convex die and multi-line sweeping concave die in the first stage, conical convex die and flat anvil in the second stage, two flat anvils in the third stage. The new axial upsetting process could improve the quality of the large forgings with more uniform deformation and less barreling.