Papers by Author: Lin Hua

Abstract: Ring parts with small-hole and deep groove such as duplicate gear and double-side flange, are widely used in various engineering machineries. Three-roll cross rolling (TRCR) is a new advanced plastic forming technology for the processing of rings with small-hole and deep groove. In this paper, a 3D coupled thermo-mechanical FE model for TRCR of ring with small-hole and deep groove is established under ABAQUS software environment. By simulation and analysis, the evolution and distribution laws of strain and temperature in the forming process are revealed, and the effects of the key process parameters on the deformation uniformity are explored. The results provide valuable guideline for the technological parameter design and optimization.

Abstract: Ring parts of duplicate gear, double-side flange, high pressure value body, are widely used in engineering machinery, have the common geometrical characteristic of thick-wall, small-hole and deep-groove on the surface. High energy consumption, low material utilization, low productivity and poor quality exist in the current forging technology of this type of rings. In this paper, a new forming method for this type of rings named combined ring rolling (CRR) is proposed. The forming principle of CRR is introduced at first, then, a 3-D coupled thermo-mechanical FE model for the CRR process of a double-side flange ring is developed. By simulation and analysis, the feasibility of CRR technology is testified, and the evolution and distribution rules of stain, temperature, force and power in the rolling process are revealed. The results provide the guideline for the research and development of CRR technology.

Abstract: Cold ring rolling is a kind of advanced manufacturing technology. During rolling process the ring may be collapsed or deformed unexpectedly under the pressure of guide roll because the stiffness condition is not met. The force of guide roll to ring was obtained by analyzing the forces to ring. The stiffness condition expressions of ring during rolling were shown after constructing the mechanical model. According to the expressions, the effects of several parameters on the stiffness condition were discussed and analyzed in detail, such as position angle of guide roll, friction coefficient and feed rate, etc, which revealed essential reasons of some cases occurring in cold ring rolling. Then the ring blank dimension was deduced based on the ring stiffness condition. The dimensions of ring blank should meet a relationship to ensure the ring stiffness condition to be satisfied during rolling, which can conduct the practical manufacturing effectively. Finally the analysis and effect laws were proved by finite element simulation experiments. The researches could be helpful to control parameter in cold ring rolling effectively for high quality products.

Abstract: The influence of process conditions on the formability of injection-molded PX0034 (9% talc-filled PP) automobile B column mounting trim applied as a model has been studied in current work. This study has been focused on the interactive influence of melt temperature and mold temperature, the interactive influences of injection time and packing time and the influences of packing pressure. Weighting the effect of optimization is by formability including the values of pressure at V/P switchover, volumetric shrinkage differential at ejection, and maximum warpage. Aforementioned values were obtained by numerical simulation of the whole molding process using commercial dedicated code Moldflow. Results indicate that the combination of mold temperature at 25 °C, melt temperature at 220 °C, injection time at 2.2 s, packing time at 16 s and packing pressure at 90% of the filling pressure is the optimal setting for formability of this trim. The simulation results obtained under the optimized parameters are that the pressure at V/P switchover is 27.29 Mpa, the shrinkage differential at ejection is 6.55 %, and maximum warpage is 3.072 mm. Good correlation is highlighted between the experiments and the simulations by comparing effects of the global optimization in formability, which verifies the validity of the optimal combination.

Abstract: Special rolling is also called rotary forming process, which is an advanced manufacture technology of making workpiece generate deformation in a rotary state by continuous local plastic forming. Disk rotary parts with outer stepped cross-section, such as wheels, flanges, valves and so on, are widely used in engineering machinery. Traditionally, this kind of part is manufactured by forging and cutting, which consumes a lot of energy and materials especially to the large size part. In this paper, a new specific rolling technique called three rolls cross rolling is first presented to produce this kind of part, and the principle and characteristics of this technique are described in detail. Then, base on the principle of the three rolls cross rolling, a 3D coupled thermo-mechanical FE model is developed under ABAQUS software environment. As a result, under the simulation and analyses of a real example, the feasibility of this technique is verified, and the evolutional laws of the strain, temperature and rolling force and power parameters during the process are investigated as well. The obtained results provide valuable guidelines for the further investigation on the forming characteristic of the three rolls cross rolling technique.

Abstract: A novel metal plastic forming technology, cold rotary forging with double symmetry rolls, is presented on the basis of cold rotary forging with single roll. A reasonable 3D elastic-plastic dynamic explicit FE model of cold rotary forging with double symmetry rolls is developed under the ABAQUS software environment. Through simulation, the distributions and histories of different field-variables such as stress, strain and force and power parameters are investigated in detail. The research results not only provide an advanced and innovative technology for metal plastic forming, but also help to better understand cold rotary forging with double symmetry rolls.

Abstract: The Conical Ring with Inner Steps (CRIS) is a typical profile ring, which is hard to be formed by ring rolling. Less-profile-filling and shrinking-drawing are the two main defects formed in the rolling process. Through the study of the rolling formability of CRIS with different ratio of height to diameter with the combination of FEM simulation method and experimental method, the main factors that affect the CRIS rolling formability are determined. The CRIS forging is designed. And the FEM simulation and experimental results show that the design method is reasonable.

Abstract: An effective method was proposed to simulate and control the motion track of guide roller during radial-axial ring rolling in FE simulation. The 3-D finite element model was constructed according to the principle and feature of rolling technology. The rolling process was simulated and analyzed by using dynamic explicit finite element technology. The different rolling processes with different technology parameter were simulated. The width spreads and rolling forces under different parameters are compared and analyzed. The results indicated that high quality ring product could be obtained when rational parameters in radial and axial were assigned.