Papers by Author: Shao Gang Liu

Abstract: The static EOQ (economic ordering quantity) model for manufacturing/remanufacturing hybrid system was improved from the point of view of time-value of system costs, and further considered the effect of time-value of money in inventory management of the hybrid system. A modified dynamic EOQ model based on time-value of system costs was proposed for a hybrid system. The main purpose of the dynamic EOQ model was to study how to determine optimal ordering quantity of the hybrid manufacturing/remanufacturing system. A numerical comparison analysis between the different models was given to illustrate the difference of the average cost and the optical ordering quantity. The results shown the modified EOQ model was often considered a more correct way in the hybrid manufacturing/remanufacturing system. The sensitivity analysis was also made to investigate the effects of main parameters on the modified EOQ model.

Abstract: Tolerance allocation have significant influence on the manufacturing cost and quality loss cost. In order to obtain optimal tolerance, Lagrange multiplier method is used to minimize the summation of manufacturing cost and quality loss cost subject to constraints on product functional requirement. The reciprocal power cost-tolerance model with different functional constraints is considered, and closed-form optimal tolerances are obtained. Using the model proposed in this paper, the optimal tolerance can be obtained quickly and accurately. One example is used to illustrate the method proposed in this paper.

Abstract: The asymmetric quality loss functions with the triangular distribution for determining the optimum process mean are studied. The condition of using the linear and quadratic asymmetric quality loss function in the model is considered. The eight mathematical models under an asymmetric quality loss function with the triangular distribution based on the analysis of the linear and quadratic asymmetric quality loss function are presented. Finally, the validity of models is verified by the examples.

Abstract: This paper presents a analytical method to calculate the minimum clamping force to prevent slippage between the workpiece and spherical-tipped fixture elements during milling process. After the contact deformation between the workpiece and spherical-tipped fixture element is determined, the relationships between the workpiece displacement and the contact deformations are obtained. Based on the static equilibrium equations, these equations are combined and linear equations are obtained to calculate the tangential contact forces between the workpiece and spherical-tipped fixture element. According to the maximum tangential contact force, the minimum clamping force to prevent slippage between the workpiece and spherical-tipped fixture elements is calculated. At last, this method is illustrated with a simulation example.

Abstract: Convolution method is studied to analyze statistical tolerance for linear dimension chain and nonlinear dimension chain. Hybrid convolution method is proposed, which is the integration of analytical convolution and numerical convolution. In order to reduce the algorithm errors, improved convolution method is proposed. Comparing with other statistical tolerance analysis methods, this method is faster and accurate. At last, an example is used to demonstrate the method proposed in this paper.

Abstract: The traditional manufacturing cost-tolerance function is improved from the point of view of the time value of money, and this makes manufacturing cost in tolerances design more actual. A comprehensive mathematic model is constructed for the concurrent tolerance optimal design based on the time value of manufacture-quality loss cost. Purpose of the establishment of the model is equivalent calculation for cost-tolerance function and quality loss function of different time points, so as to make them calculated in the same time point, and concurrent tolerance optimal design is achieved. This modified model’s validity is proven by an illustrative example.

Abstract: During manufacturing processes, firstly the raw materials are mined or recovered from ore. Then the raw materials are machined to obtain the qualified component. In this paper, energy consumption of manufacturing processes is calculated. During the manufacturing processes, usually several stages are needed, which are rough machining, semi-finish machining and finish machining. After each stage is finished, the components are inspected and classified into three groups: (1) those below the specification, (2) those within the specification, (3) those above the specification. For each category, the corresponding energy consumption is calculated. At last, the energy consumption of whole manufacturing processes is obtained.

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.