Papers by Author: Ping Wang

Abstract: Usually the gearbox casing of twin screw pulping extruder was designed by experience and greater weight. In order to reduce the casing weight under the premise of ensuring its stiffness and strength, firstly the casting lower box and the weakest axle in the casing were analyzed with finite element method by ANSYS software. And then the optimum design was carried out to take the minimum volume as an objective function. Finally, the welding casing has been designed as considering the manufacturing cost. The results show that the weight of the casting lower box after optimization is 22.95% lower than that of the experience design, and the weight of the welding part is 19.09% lower than that. The work has certain significance for optimum design of gearbox casing.

Abstract: In order to select rational screw parameters for improving the pulping quality, efficiency and reducing specific energy, the paper studied the effects of the rotational speed of screw, lead number of reverse thread and slot width of reverse flight of the twin screw pulping extruder (TSPE) on specific energy, flux and pulping quality (reject rate, fiber length and fine component content) in the processes of extrusion mechanical pulping. The experimental results show that synthetically considering and pulping quality the efficiency, the screw rotational speed of 300 r/min–400 r/min is more appropriate. For poplar chips, the lead number should be greater than or equal to six. And for cotton stalks and wheat straws, the lead number should be no less than seven. For the combination screws of multiple extrusion zones, the slot width of the ultimate extrusion zone plays a decisive role on the fiber length. In addition, the slot width can also adjust the barrel pressure and the axial force of the screws. The work of the paper is significant for optimum design of the TSPE.

Abstract: In order to reduce the energy consumption and gear’s weight of drive system, based on electromechanical driving dynamics, the paper discussed the influence on rotary inertia of motor shaft caused by drive system of multi-shaft varying speed and its actuator, analyzed the influence on energy consumption and cycle of the motor’s startup or brake by sum rotary inertia (SRI), and explained the problems related to rotational speed of the motor and drive system design, also brought forward methods on weight reduction design (WRD) of drive system. Case studies show that in multi-shaft reduction drive, the ratio of the drive system rotary inertia on the SRI of the motor shaft is from 5.377% to 18.567%. Therefore, weight reduction of the drive system has obvious effect on lessening the energy consumption and cycle of the motor’s startup or brake. And the work of the paper offers theoretical gist for WRD of drive system.

Abstract: Formulas of flux and power consumption of twin screw pulping extruder (TSPE) based on extrusion model deal with nearly all of geometrical and mechanical parameters of the twin screw and the material processed, they are not convenient for estimation and initial design of the machine. Adopting dimensional analysis based on similarity theory and considering the most important factors, such as outer diameter of screw, rotational speed of screw and average pressure between barrel and material processed, estimation equations of flux and power consumption of the TSPE are deduced in the paper, and the correction coefficients are determined by experiment data. The estimation results show that the estimation and theoretical results have similar changeable trend although there are some errors. The work is easy to apply in the estimation and initial design of the TSPE, and complement the design theory and method of the TSPE.

Abstract: In order to meet the requirements of high torque and small center distance of the twin screw pulping extruder, an improved design method of the crown gear coupling (CGC) was studied. Based on the preliminary structural design, the paper selected parameters of tooth form of the crown gear firstly, and according to the contact strength solved the tooth width, then the discussed influences of radius of displacement circle and unilateral thinning amount on tooth thickness, finally through the finite element analysis verified the design results. The results show that under the condition of radial restriction the most effective ways to increase load-bearing capability of the CGC are to improve the tooth stiffness and increase the tooth width, and the increasing of tooth width should consider the tip strength of the crown gear and avoid over-cutting. The CGC design method of the paper can meet the requirements of the twin screw extruder.

Abstract: In order to enhance design reliability of a co-rotating twin screw pulping extruder (TSPE), optimum design on screw parameters of the TSPE was studied based on the extrusion model. The maximum shear flux or the minimum power consumption, or the two synchronous optimizations were taken as objective functions, and constraint conditions, such as thread lead, depth of thread, screw rotational speed, number of reverse thread lead, actual top width of the flight, torsional strength and stiffness of the screw mandrel, and so on were confirmed base on actual requirements of the TSPE manufacture and application. The optimizing results show that two-objective optimum design results split the difference of the two single-objective optimum design, and it is the most economical in reducing manufacture cost of the equipment and pulping expenses.

Abstract: . For a medium or large-sized gear drive, in order to achieve the optimum weight reduction effect, an approach of weight reduction design is proposed that multi-objective optimization of gear parameters is carried out firstly, and then structural optimization is adopted to design the gear former. The rational design parameters of a gear drive are determined by the multi-objective optimization with minimizing the sum of gear volumes and the equivalent moment of inertia of input shaft (EMI) synchronously. Conceptual design of the former is given by structural topology optimization of the gear, and the reasonability of topology optimization can be demonstrated by static and dynamic analysis. The results indicate that for a double-reduction gearbox of 500KW co-rotating twin screw pulping extruder, the EMI of the gear drive reduces by 20.88% through the multi-objective optimization of gear parameters, and the moment of inertia of a bull gear reduces by 38.86% through structural topology optimization.

Abstract: The dynamic seal mechanism of hydrodynamic reciprocating sealing is discussed. TRIZ S-Field model and standard solutions is proposed. The reliability and effectivity S-Field models of hydrodynamic reciprocating sealing are constructed according to typical hydrodynamic reciprocating sealing configuration shapes, such as O-ring sealing, Y-ring sealing and polymer sealing. The leakage and failure problems solutions of hydrodynamic reciprocating sealing as well as their configuration realization are studied based on TRIZ S-Field analysis and standard solutions, which offer powerful theoretic guides for efficiency-reinforcement technology of hydrodynamic reciprocating sealing.

Abstract: In order to design trapezoidal thread parameters of co-rotating twin screw extruder that is used in non-fused materials processing, based on geometry of fully wiped co-rotating twin screw extruder by M. L. Booy, the paper adopts tangential approximation method to determine the parameters of trapezoidal thread choosing tangent of especial point of normal section curve. And reasonable spans of oblique angle, actual top width of flight, channel depth and thread lead are determined by the optimum design with objective function of maximal theoretical flux. Experiments show that a co-rotating twin screw pulping extruder of trapezoidal thread designed by the method is easier to machine and measure, and pulp processed by the twin screw pulping extruder can meet the quality requirements. Thus, twin screw designed by the method reserves the main strongpoint of the fully wiped co-rotating twin screw extruder.

Abstract: In order to calculate important design parameters, screw axial force and power consumption of twin screw pulping extruder (TSPE), considering actions of the solid material plug in reverse thread of the TSPE and according to static balance principle, an extrusion model including plug flowing and shearing in reverse thread is proposed in the paper. Based on the model, screw axial force, screw torque, power consumption and flow rate can be derived. When changing thread lead numbers or slot width on the flight of the reverse thread, theoretical calculating results and testing results are better consistent.