Applied Mechanics and Materials Vols. 10-12

Abstract: Virtual manufacturing (VM) is an emerging technology that provides a digital tool for the optimization of the production efficiency through simulations prior to the start of actual production. A NC program translator is one of the crucial components for virtual machining which allows the simulation and verification of NC tool path before actual machining. In this paper, a framework of a NC program translator for diamond turning of precision optics is presented.

Abstract: Many research show that in metal cutting process wear rate is dependent on the cutting process variables such as temperature at tool face, contact pressure (normal stress) and relative sliding velocity at tool/chip and tool/work interface; their relationship is described by “differential” wear rate model. Based on this “differential” wear rate model, a method to estimate tool wear in milling operation is proposed and the cutting process variables are predicted by performing chip formation analysis with FEM code ABAQUS/Explicit and heat transfer analysis with ABAQUS/Standard. The implementation is exemplified by estimating tool wear of carbide tools in milling of Ck45 work. Both progressive flank wear and crater wear profile are estimated.

Abstract: When using the formed milling cutter to machine workpiece, the formed parts are cut by the milling with formed shape, so forms correspond to workpiece outline. In the 3D design software--SolidWorks, the relation of position of the workpiece profile and the milling each other is simulated. This project uses the function of 3D-shape of software to complete the 3D-entity-design of formed milling cutter profile and the drawing of rake face, thus designing the rake face profile directly, with the results of a great improvement on the design and machining quality and effectiveness.

Abstract: The prediction accuracy of the simulation of cutting process is related with the description of the nonlinear behavior of material at extremely high strain, strain rate and temperature in machining. In this paper, an integral Johnson-Cook model is presented to characterize the mechanical behavior of work materials in machining, and the parameters in the model are determined by fitting the data from both quasi-static compression and cutting tests. Then the material equation of 2Cr13 stainless steel is derived with this method and used in the finite element model of orthogonal cutting with carbide tools. At last, the simulation result is verified with experimental data.

Abstract: Computer-aided design tolerances (CADT) technology got far behind the CAD, CAPP, CAM etc, although there are many commercial tolerance software, but the tolerance optimal design still can’t be completed, which seriously affects the CAX technology's integral roles. Based on the tolerance computation function of the UG Quick Stack module, this paper accomplishes the product assembly relation modeling, tolerance distribution, locked circle calculation and so on, achieves the optimal design tolerance of whole product.

Abstract: In this paper the model of special metal cutting NC machine Tool is presented, which consists of a base module, an overall control module, particular functional modules as well as a relation module. Each module involved in aforementioned model will be composed by software, hardware and mechanical parts, so as to combine the convergence of the ideas of modularization and mechanical-electrical integration into current understanding of special NC machine tool through the proposed model. Specially, the relation module is introduced to deal with the linking among all the other modules. The presented model aims to broaden the perspective of machine designers intending to increase the efficiency in machine design. By giving the so-called function unit model a novel modeling approach is delivered to carry out control research of special metal cutting NC machine, which is followed by the formalization description method presented as a possible abstraction methodology towards the efficient description and identification of special metal cutting NC machine tool.

Abstract: This paper deals with an on-line mismachining error measurement for curve grinding based on digital image processing. Using CCD camera, the contour of the workpiece’s finished surface is captured and the image is preprocessed for denoising and edge detecting. The worktable is guided by the image of the finished workpiece to follow the path of the finished contour and then the real curve of the finished workpiece is measured by fitting a curve according to the moving path of the worktable. Finally, the machining error is obtained by comparing the measured curve with the theoretical curve of the workpiece. This method is applied to a CNC curve grinding machine MD9040. A measurement experiment is given. The experiment results show that the measurement method offers high detection precision and can be used in wide fields, especially for measuring the parts with complex curve.

Abstract: The combination of metal cutting theory, computer technology and expert knowledge was used to study the use of knowledge-based engineering (KBE) for cutting large containers. This report includes information on the acquirement, expression, and inference and management of KBE. The structure of the KBE system was established by selecting the principles of processing parameters and optimizing the model of machining data and by using the method of expressing knowledge of combining producing type with frame type and by using the software SQL server 2000. The inferential mechanism of every functional module in the system was realized by applying the software, VC++ 6.0. The KBE technology will help technicians to share expert knowledge and experience, and to optimize cutting parameters to intellectualize cutting design and machining.

Abstract: The realistic dynamic image of virtual milling process is important in the field of virtual manufacturing technology. However, it is difficult to realize virtual 3-D workpiece model removing process. Material removal algorithm model based on an adaptive dynamic quadtrees algorithm is proposed in this paper. Based on mathematical model of virtual material removal, the 3D model of virtual CNC milling process was developed. The real-time simulation of material removal process was realized in the virtual reality environment.

Abstract: For the measurement of ultra smooth surface topography, a surface image scanning device measurement head mechanism based on the principle of atomic force microscope (AFM) was designed. It uses coarse adjustment, semi-delicate adjustment, delicate adjustment triple-stage adjustment mechanism, and tests the atomic force between the sample and the probe by using laser generator, position sensitive detector (PSD), cantilever and probe. This mechanism has high setting accuracy and resetting accuracy, combined with two-dimension movable table, can scan the surface topography of samples.