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2.
A STEP-compliant CNC machine tool that demonstrated a G-code free machining scenario is presented. The aim of this research is to showcase the advantages of, and evaluate, STEP-NC—a new NC data model—by implementing it in a legacy CNC system. The work consists of two parts: retrofitting an existing CNC machine and the development of a STEP-compliant NC Converter called STEPcNC. The CompuCam's motion control system is used for retrofitting the machine, which is programmable using its own motion control language—6K Motion Control language and capable of interfacing with other CAPP/CAM programs through languages such as Visual Basic, Visual C++ and Delphi. STEPcNC can understand and process STEP-NC codes, and interface with the CNC controller through a Human Machine Interface. It makes use of STEP-NC information such as “Workplan”, “Workingstep”, machining strategy, machining features and cutting tools that is present in a STEP-NC file. Hence, the system is truly feature-based. The Application Interpreted Model of STEP-NC has been used. 相似文献
3.
Inappropriate machining conditions such as cutting forces cause tool failures, poor surface quality and worst of all machine breakdowns. This may be avoided by using optimal machining parameters, e.g. feed-rate, and continuing to monitor it throughout the machining process. To optimize feed-rate, we propose a system that consists of an optimisation module, a process control module and a knowledge based evaluation module. STEP-NC is the underlying data model for optimisation. Given the nominal powers, the cutting force can be estimated based on the higher-level production information such as workpiece properties, tool materials and geometries, and machine capabilities. The main function of the Process Control module is process monitoring and control. The output is the desired actual feed-rate. Finally, the actual feed-rate is recorded and evaluated in the Knowledge Based Evaluation module. 相似文献
4.
In the paper a realistic approarh to fuzzy control of urban road traffic lights is described. Fuzzy application is encouraging since the design procedure of vehicle actuated traffic light systems is very transparently, and an adaptation to changing situations of traffic is easily to accomplish. The paper presents simulation results obtained for an intersection with 12 main direction traffic flows. The fuzzy controller proposed switches to a two-state, a three-state or a four-state control. The results with respect to the average loss of traveltime are very promising in comparison with other controllers applied to the same simulation example. 相似文献
5.
The computation of an optimal feedback controller characteristic for a non-linear stochastic system may be facilitated by the use of a stochastic automaton as a system model. A problem of particular interest is that of a long duration stationary Markov process in which the state is observable but the process dynamics and disturbance characteristics are initially unknown. The determination of a suitable control algorithm, in the form of an adaptive automation in the feedback loop, is considered in this paper for such a process. Since the algorithm is to be used on-line to perform simultaneously the functions of estimation and control, it must constitute an efficient convergent multi-stage dual control strategy. It is shown that an existing method for dual control of a repetitive single-stage stochastic process may be extended to apply to the present case. A method is introduced of calculating successive policy estimates recursively, so that the task of updating the estimated optimal feedback policy at each stage of the process is rendered feasible. The application of the automaton controller is illustrated by the simulated adaptive control of a non-linear conditionally stable heat treatment process disturbed by multiplicative noise. 相似文献
6.
In this paper, an hybrid system is proposed for setting machining parameters from experimental data. A symbolic regression alpha–beta is used to build mathematical models. Every model is validated using statistical analysis then evolutionary computation is used to minimize or maximize the generated model. Symbolic regression α– β is used to build mathematical models by estimation of distribution algorithms. A practical case considering measured data of two machining process on three materials are used to illustrate the utility of the expert system because generates a set of parameters that improve the machining process. 相似文献
7.
A key component of computer integrated manufacturing (CIM) is computer aided process planning (CAPP). Process planning in machining involves the determination of the cutting operations and sequences, the selection of machine tools and cutting tools, the calculation of machining parameters, and the generation of CNC part programs. Industrial structures in Norway are defined as small and medium-sized companies. The important fact is how well these companies use high technologies and resources in order to improve their production efficiency, product quality, and company competition in international markets. The concept of an integrated intelligent system (IIS) is created for this purpose. A prototype system, the integrated intelligent process planning system (IIPPS), is described for machining; it was developed on the basis of an IIS and constructed using three levels of effort: (1) AutoCAD, (2) dBASE III and (3) KnowledgePro. The system may be utilized not only by a process plann ing engineer in a company, but also by students of mechanical or industrial engineering. 相似文献
8.
The object-oriented STEP-NC data model provides a seamless and integrated programming interface for on-machine (or also known as on-line or in-line) inspections as well as interoperable manufacturing. This paper proposes a STEP-NC data model for on-line inspections. A framework of STEP-NC enabled closed-loop machining is also presented. The aim is to achieve a fully closed computer-aided design, process planning, machining and inspection chain. A new version of STEP-NC Interpreter has been developed to implement the proposed framework. A case study is included to demonstrate the implementation. 相似文献
9.
Fixture planning is an important part of computer-aided process planning (CAPP), which is the link between design and manufacturing in a CIM environment. This paper presents a rational approach to computer-assisted fixture planning (CAFP), emphasizing integration of fixture planning with process planning, an issue that has not been adequately addressed until very recently. A systematic approach to fixture selection is outlined for planning of modular fixtures. A prototype CAPP-CAFP system has been developed at UCLA and linked to a commercial CAD system, namely, CADAM. Part design information can be extracted from the CAD model and multiple-view engineering drawings of a part stored in the CADAM system. Modular fixture elements can be selected automatically by the CAPP-CAFP system and the generated fixture layout can be displayed on the screen. Included also in the system is a fixture analysis module for verification and rationalization of a fixturing scheme. The force analysis module has a built-in local optimization routine that can determine the clamping forces of more reasonable magnitudes. The friction forces between the fixture and the workpiece can also be considered for simple cases. 相似文献
10.
On-line manufacturing systems for continuous production are traditionally checked by constant time-based inspection and statistical process control processes. In the monitoring operation of large scale process plants, it is important to detect and locate process variables as they can significantly modify the operation and quality of the products involved. The present paper explores an alternative for monitoring these systems that uses the open loop control paradigm. The proposed method is defined and presented as an application for one particular industrial process—rubber die extrusion. The advantages of this method for this particular application, including its implementation throughout a multi-agent system, compatible with the HoloMAS paradigm for managing, modeling and supporting complex systems, are also discussed. 相似文献
12.
It is generally recognised that industrial processes depend heavily on sequential control. Paradoxically, this technique of control has received from control theorists, less attention than it deserves. In view of its logical basis, this class of control is an ideal candidate for rule-based expert systems. Features of one such expert system are presented in this paper, along with observations related to the development of expert systems for process control. 相似文献
13.
Manufacturing paradigms over the last 150 years have changed from craft production, to mass production and now to mass customisation. One further extension of mass customisation is personalised manufacture, which is the concept of providing bespoke products to the individual consumer. As a result this has brought about the need for a greater degree of sophistication in manufacturing practises and the technologies employed. This bespoke form of manufacture of consumer goods is now being pursued on CNC machining centres as opposed to the alternative of highly expensive rapid prototyping methods. The problem with this form of manufacture is that the products are generally free formed objects which require sophisticated setups and machining. Ball-end machining is a method used to create cusp-type geometry, which is employed on CNC machines to create sculptured surfaces. The objective of this research is to provide a predictive model using a design of experiments strategy to obtain optimised machining parameters for a specific surface roughness in ball-end machining of polypropylene. This paper reports on new manufacturing knowledge to machine polypropylene using ball-end tooling in order to generate personalised sculptured surface products. 相似文献
14.
This paper presents a real-time intelligent supervision system for IC ion implantation processes. A hardware interface is developed, to extract the features directly from the 2-D analog image signals of a beam map. A qualitative model for the beam scanning is then obtained, and the symptoms of abnormal operations can be analyzed to achieve on-line diagnosis. Furthermore, a fuzzy expert system is developed to advise operators on making appropriate adjustments for the beam scanning. This supervisory system has been implemented on Eaton NV-6200 A/AV ion implanters at the Taiwan Semiconductor Manufacturing Company. 相似文献
15.
With the development of manufacturing,numerical control(NC) machining simulation has become a modern tool to obtain safe and reliable machining operations.Although some research and commercial software about NC machining simulations is available,most of them is oriented for G&M code.It is a low-level data model for computer numerical control(CNC),which has inherent drawbacks such as incomplete data and lack of accuracy.These limitations hinder the development of a real simulation system.Whereas,standard for the exchange of product data-compliant numerical control(STEP-NC) is a new and high-level data model for CNC.It provides rich information for CNC machine tools,which creates the condition for an informative and real simulation.Therefore,this paper proposes STEP-NC based high-level NC machining simulations solution integrated with computer-aided design/computeraided process planning/computer-aided manufacturing(CAD/CAPP/CAM).It turned out that the research provides a better informed simulation environment and promotes the development of modern manufacturing. 相似文献
16.
Unconventional machining processes (communally named advanced or modern machining processes) are widely used by manufacturing industries. These advanced machining processes allow producing complex profiles and high quality-products. However, several process parameters should be optimized to achieve this end. In this paper, the optimization of process parameters of two conventional and four advanced machining processes is investigated: drilling process, grinding process, abrasive jet machining, abrasive water jet machining, ultrasonic machining, and water jet machining, respectively. This research employed two bio-inspired algorithms called the cuckoo optimization algorithm and the hoopoe heuristic to optimize the machining control parameters of these processes. The obtained results are compared with other optimization algorithms described and applied in the literature. 相似文献
17.
Continuous quality improvement calls for employing methodologies that assist in continual reduction of variations in process performance characteristics around their target values. The study considers a case in which some of the operations process parameters/inputs are required to take values in pre-specified ranges. To improve the process performance while accounting for these requirements, the study employs a neural network-based model-free controller along with the penalty function. Simultaneous perturbation stochastic gradient approximation method is used to iteratively estimate the weights of neural network and as a result to estimate the control values. Furthermore, the study uses a special cause control chart to monitor the performance of the controller in reducing the process variations and to signal the change in the process dynamics. Simulation findings indicate that the neural network model-free provides control values that result in fewer nonconforming outputs than when the requirements are not incorporated in optimization process 相似文献
18.
The present work proposes a systematic methodology for the optimal selection of controller parameters in the sense of minimizing a performance index, which is a quadratic function of the tracking error and the control effort. The performance index is calculated explicitly as an algebraic function of the controller parameters by solving Zubov's partial differential equation (PDE). Standard optimization techniques are then employed for the calculation of the optimal values of the controller parameters. The solution of Zubov's PDE is also used to estimate the closed-loop stability region for the chosen values of the controller parameters. The proposed approach is finally illustrated in a chemical reactor control problem. 相似文献
19.
The development of a more cost effective graphics controller, aiming at less analogue circuitary with fewer adjustments and an easier method to change drawing speed. 相似文献
20.
This paper deals with an automatic setup planning system for machining processes of prismatic parts. The proposed system concurrently implements both machining sequences of reference surfaces and machining sequences of features for the purpose of minimizing number of setups in setup planning. Experienced planners' knowledge are represented as rules and used for machining sequences of reference surfaces and they are implemented by using EXSYS. A case study is performed to evaluate the performance of the proposed system. 相似文献
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