Yiming Rong

Case-based agile fixture design

Abstract In this paper, the general situation of research on agile fixture design is summarized and the achievements and deficiencies in the field of case-based fixture design are pointed out. There are no correlative case bases and matching mechanisms during the period from establishing the fixture planning to designing the fixture in currently used case-based fixture design systems. Thus a great amount of experience of fixture design is wasted and cannot be re-used, which reduces design efficiency and violates the original intention of case-based reasoning methods. In order to realize agility of fixture design, including re-configurability, re-scalability and re-usability, in this paper, a re-configurable agile fixture element base and an element assembly relation base are established. Using these two bases, the fixture structure is function-based decomposed, which makes it easy for an agile fixture to be re-configured and modified. Furthermore, a whole case-based agile fixture design model is presented, in which three modules are introduced, including the evaluation of the similarity of fixture planning, conflict arbitration and the modification of an agile fixture case. The three modules can be used to solve a problem where experience and design results cannot be re-used in the process of fixture design. Against the agile fixture design model, the evaluation method is put forward to evaluate the similarity in various phases. However, a similar case in the base could not generally meet the actual requirement and resolve the conflict between the similar case and the actual condition. Thus three methods, including a local restriction-relaxed method, a function-based conflict arbitration method and a case-based conflict arbitration method, are presented to clear up the conflict and could be used to modify the case to obtain an approach to a design result. Finally, an agile fixture design example is presented. The result demonstrates that the case-based agile fixture design approach can improve re-usability and design efficiency.

FEM Modeling of Induction Hardening Processes in Steel

A modeling system for analyzing the integrated induction hardening processes was developed based on a general-purpose finite element program, with the capability to analyze the whole process from electromagnetic-induced thermal heating to final hardening. A coupled electromagnetic-thermal model was applied to study the induction heating process, which includes consideration of nonlinear material characteristics on temperature. Also, arrangement of AC current density distribution was conducted to simulate practical induction coil structure and magnetic concentrator effects to achieve desired heating patterns for later quenching and hardening analysis. Quenching analysis can provide cooling curve at any location in a heat-treated workpiece based on heat transfer principles. In hardening analysis, phase transformation was studied and an algorithm was developed to determine volumetric content of micro-structural constituents formed from austenitized phase in quenching process, based on analysis of the interaction between cooling curve and material time-temperature-transformation (TTT) diagram. Finally, hardness value was converted from martensite content based on a developed formulation. Validation was preliminary conducted based on comparison of hardening pattern of induction hardening of an automotive spindle with complex surface.

The effect of cutting fluids applied in metal cutting process

Due to the development of new engineering materials and high-speed cutting, cutting fluid plays an important role in machining. Commonly, the use of cutting fluid can decrease cutting temperature, reduce the friction between tool and workpiece, extend tool life, and improve machining efficiency and surface quality. These effects of cutting fluid were mainly obtained from its basic functions including cooling, lubrication, corrosion protection, and cleaning. According to the review of the researches in cutting fluids applied in metal cutting process, the available researches mainly focused on the application strategies and penetration capability, processing performance, new types of environmentally friendly cutting fluids, and preliminary machined surface quality. This article also suggests that the effect of cutting fluid on machined surface quality and performance will become an important research direction. There is a matching problem between the cutting fluids and the workpiece materials. Further research on effect of cutting fluids on machined surface should include physical and chemical mechanism of the cutting fluid, action mechanism on fresh machined surface during machining process, action mechanism in the period of long-term service, stability of the composition and physical and chemical properties, and evaluation method of the effective use of cutting fluid.

Applying an electromagnetism-like mechanism algorithm on parameter optimisation of a multi-pass milling process

Multi-pass milling is a common manufacturing process in practical production. Parameter optimisation is of great significance since the parameters largely affect the production time, quality, cost and some other process performance measures. However, the parameter optimisation of the multi-pass milling process is a nonlinear constrained optimisation problem. It is very difficult to obtain satisfactory results by the traditional optimisation methods. Therefore, in this paper, a new optimisation technique based on the electromagnetism-like mechanism (EM) algorithm is proposed to solve the parameter optimisation problem in a multi-pass milling process. The EM algorithm is a population based meta-heuristic algorithm for unconstrained optimisation problems. As the parameter optimisation problem is a constrained problem, the proposed approach handles the constraints of the problem by improving the charge calculation formula combined with the feasibility and dominance rules at the same time. This paper also puts forward flexible cutting strategies to simultaneously optimise the depth of cut for each pass, cutting speed and feed to improve solutions. A case study is presented to verify the effectiveness of the proposed approach. The results show that the proposed method is better than other algorithms and achieves significant improvement.

Intelligent disassembly planning: a review on its fundamental methodology

Purpose – The purpose of this paper is to review the fundamental methodology and its development of intelligent disassembly planning research.Design/methodology/approach – Following a brief introduction, this paper first discusses the fundamental problems associated with disassembly planning and analysis. And then considers the role of intelligent optimization methods in the disassembly planning field. This is followed by a summary and conclusion.Findings – Many advances have been made in computerized intelligent disassembly planning research, which is a natural evolutionary result of both traditional solving methodology and much research effort over past two decades. But as yet, some fundamental limitations are also rooted in this computational model‐based methodology.Originality/value – The paper provides a fundamental review on the development of computerized intelligent disassembly planning research.

A STUDY ON CHIP BREAKING LIMITS IN MACHINING

Prediction of chip breaking in machining is an important task for automated manufacturing. This paper presents a study on chip breaking limits. Based on the chip breaking curve, the critical feed-rate is modeled through an analysis of up-curl chip formation, and the critical depth-of-cut is formulated through a discussion of side-curl dominant chip formation processes. Factors affecting chip-breaking limits are also discussed. In order to predict the chip breaking limits, semi-empirical models are established. Although the coefficients that occur in the model are estimated through machining tests, the models are applicable to a broad range of machining conditions. The model parameters include machining conditions, tool geometry, and workpiece material properties.

A Finite Element Analysis For Stiffness of Fixture Units

This paper presents a systematic finite element model to predict the fixture unit stiffness by introducing nonlinear contact elements on the contact surface between fixture components. The contact element includes three independent springs: two in tangential directions and one in the normal direction of the contact surface. Strong nonlinearity is caused by possible separation and sliding between two fixture components. The problem is formulated by the penalty function method and is solved by the Newton-Raphson procedure. The model was validated by two cases of analysis of a linear cantilever beam and a simple fixture unit with two components. The results are in agreement with the corresponding analytical solution of beams and the previous experimental results for fixture in the literature.

Numerical Simulation of the Moving Induction Heating Process with Magnetic Flux Concentrator

The induction heating with ferromagnetic metal powder bonded magnetic flux concentrator (MPB-MFC) demonstrates more advantages in surface heating treatments of metal. However, the moving heating application is mostly applied in the industrial production. Therefore, the analytical understanding of the mechanism, efficiency, and controllability of the moving induction heating process becomes necessary for process design and optimization. This paper studies the mechanism of the moving induction heating with magnetic flux concentrator. The MPB-MFC assisted moving induction heating for Inconel 718 alloy is studied by establishing the finite element simulation model. The temperature field distribution is analyzed, and the factors influencing the temperature are studied. The conclusion demonstrates that the velocity of the workpiece should be controlled properly and the heat transfer coefficient (HTC) has little impact on the temperature development, compared with other input parameters. In addition, the validity of the static numerical model is verified by comparing the finite element simulation with experimental results on AISI 1045 steel. The numerical model established in this work can provide comprehensive understanding for the process control in production.

The Study of the Effect of Magnetic Flux Concentrator to the Induction Heating System Using Coupled Electromagnetic-Thermal Simulation Model

Induction heating is frequently used in the metalworking industry to heat metals for hardening, soldering, brazing, tempering and annealing. Due to its complexity, the using of simulation to analyze induction heating process could become very advantageous both in design and economic aspects. In this paper, an analytical model is established using commercial package Cedrat Flux® 10.3, and the model is verified by the experiments. After the establishment of analytical model, an analysis on the effect of magnetic flux concentrator was conducted.

A unified point-by-point planning algorithm of machining fixture layout for complex workpiece

Workpiece-fixturing is necessary to achieve the correct position of the workpiece with respect to the cutting tool. Therefore, a unified point-by-point planning algorithm of fixture layout is systematically created for a complex workpiece based on the discretization thought. Firstly, based on the inclusion of the theoretical Degrees of Freedom (DOFs) within the practical DOFs and the relationship between the locator number and the rank of Jacobian matrix, two necessary and sufficient conditions are suggested for the judgment criterion of locating determination. According to the variation of locating reference and locator number, a planning algorithm of locating layout is further established by iteratively analysing the locating determination. Secondly, the combination of the virtual work principle with the linear programming technology is employed to formulate a judgment criterion for fixturing stability. Consequently, with the discretization of clamping surfaces, a deterministic algorithm of clamping force is suggested by evaluating the fixturing stability at every node. Three typical examples are finally used to demonstrate the design procedure of fixture layout.