288 research outputs found

    Process simulation for 5-axis machining using generalized milling tool geometries

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    Multi-axis machining (especially 5-axis machining) is widely used in precision machining for automotive, aerospace and die-mold manufacturing. The goal in precision machining is to increase production while meeting high part quality needs which can be achieved through decision of appropriate process parameters considering machine tool constraints (such as power and torque), chatter-free operations and part quality. In order to predict and decide on optimal process parameters, simulation models are used. In the literature, individual tool geometries for multi-axis machining are examined in detailed with different modeling approaches to simulate cutting forces. In this study, a general numerical model for 5-axis machining is proposed covering all possible tool geometries. Tool envelope is extracted from CAD data, and helical flutes points are represented in cylindrical coordinates. Equal parallel slicing method is utilized to find cutter engagement boundaries (CEB) determining cutting region of the tool surface. for each axial level in the tool axis direction. For each level uncut chip thickness value is found and total forces are calculated by summing force values for each point along the cutting flutes. For arbitrary cases forces are simulated and obtained results are experimentally verified

    Reliability Analysis of On-Demand High-Speed Machining

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    Current trends in high-speed machining aim to increase manufacturing efficiency by maximizing material removal rates and minimizing part cycle times. This project explores three related technologies and presents a system design for rapid production of custom machined parts. First a reliability analysis in high-speed machining of thin wall features is put forth with experimental results. Second an implementation of on-demand manufacturing is presented with emphasis on flexibility and automation. Finally innovative manufacturing cell design is used to drive costs down by optimizing material and information flow. The resulting high-speed on-demand machining cell design employs effective techniques to reduce production time, meet changing customer needs, and drive down costs

    A digital twin study for immediate design / redesign of impellers and blades: part 1: CAD modelling and tool path simulation.

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    This paper presents a digital twining study conducted for an immediate design / redesign and manufacturing of on impellers and blades. It is by accomplished by developing (i) CAD automation methods, based on the standard modelling procedures and (ii) Manufacturing automation based on the 3/3 + 1/3 + 2/5 axis milling process. Initially, the CAD model of impeller / blade is created by utilizing the dimensional parameters obtained through standard design calculations / data. It is then parametrized and converted to an automated model through simple dimensional rules and geometric algorithms developed for the purpose. After this stage, the CAD model is analyzed for manufacturing automation where the process planning data comprising cutting tools, process parameters and setups are selected. Here, the tool paths are generated for 3/3 + 1/3 + 2/5 axis milling considering a CNC Vertical Machining Center (VMC) to digitally twin milling process. Both the CAD modelling and manufacturing process plans including tool path generation are captured through journaling and customized / improved using the Application Programmable Interface's (API's) to suit the present scope. In this paper, the first part on CAD modelling and manufacturing simulation methodologies are discussed through validating the digital twining concept in a virtual environment. The work is developed with the focus to help industries moving towards Industry 4.0 and requiring a constant design improvement in their products. It is by emphasizing the importance of digital twinning concept where a concurrent verification of design and manufacturing process can be achieved

    Mechanical and dynamical process model for general milling tools in multi-axis machining

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    Multi-axis milling operations are widely used in many industries such as aerospace, automotive and die-mold for machining intricate sculptured surfaces. The most important aspects in machining operations are the dimensional integrity, surface quality and productivity. Process models are employed in order to predict feasible and proper process conditions without relying on empirical methods based on trial and error cutting and adaptation of previous experiences. However, previously developed process models are often case specific where the model can only be employed for some particular milling tools or they are not applicable for multi-axis operations. In many cases, custom tools with intricate profile geometries are compatible with the surface profile to be machined. On the other hand, for more robust and stable cutting operations, tools with wavy cutting edge profiles and varying geometric edge distributions are utilized. In this thesis, a complete numerical mechanic and dynamic process model is proposed where the tool is modeled as a point cloud in the cylindrical coordinates along the tool axis. The tool geometry is extracted from CAD data enabling to form a model for any custom tool. In addition, the variation in the cutting edge geometry, where serrated and variable helix/pitch cutting edges can be adapted for any milling tool is taken into account. The cutting engagement boundaries are identified numerically using a Boolean intersection scheme. Moreover, a Z-mapping algorithm is integrated in the proposed multi-axis mechanistic force model to predict cutting forces for a continuous process. As for the multi-axis milling dynamics, previous single-frequency stability models are extended to encompass all possible tool geometries taking the time delay variation introduced by irregular cutting edge geometries. The proposed model is experimentally verified with different tool geometries investigating cutting forces and also predicting the stable cutting conditions

    Virtual machining considering dimensional, geometrical and tool deflection errors in three-axis CNC milling machines

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    Virtual manufacturing systems can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased. There are different error sources in machine tools such as tool deflection, geometrical deviations of moving axis and thermal distortions of machine tool structures. Some of these errors can be decreased by controlling the machining process and environmental parameters. However other errors like tool deflection and geometrical errors which have a big portion of the total error, need more attention. This paper presents a virtual machining system in order to enforce dimensional, geometrical and tool deflection errors in three-axis milling operations. The system receives 21 dimensional and geometrical errors of a machine tool and machining codes of a specific part as input. The output of the system is the modified codes which will produce actual machined part in the virtual environment

    Virtual machining considering dimensional, geometrical and tool deflection errors in three-axis CNC milling machines

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    Virtual manufacturing systems can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased. There are different error sources in machine tools such as tool deflection, geometrical deviations of moving axis and thermal distortions of machine tool structures. Some of these errors can be decreased by controlling the machining process and environmental parameters. However other errors like tool deflection and geometrical errors which have a big portion of the total error, need more attention. This paper presents a virtual machining system in order to enforce dimensional, geometrical and tool deflection errors in three-axis milling operations. The system receives 21 dimensional and geometrical errors of a machine tool and machining codes of a specific part as input. The output of the system is the modified codes which will produce actual machined part in the virtual environment

    A CAD/CAM concept for High Speed Cutting compatible rough machining in die, mould and pattern manufacturing

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    Die, mould and pattern manufacturing plays a central role in the production of capital and consumer goods. Ever-shorter product life cycles and the expanding diversity of features require continued cuts in production lead times. Recently, these developments in the market, accompanied by a simultaneous demand for improved quality at a lower cost, are becoming clearly noticeable. Along with the streamlining of organizational structures and advanced technological developments, it is above all the introduction of CAD/CAM software that offers great potential for reducing lead times for components with free surfaces. The role of milling in the integrated process chain of die, mould and pattern manufacturing is steadily gaining importance. This is due to the ongoing further development of milling-machine technology, the cutting tools and their coatings, and of the CAD /CAM systems themselves. Generally speaking, the milling process is divided into the operations of roughing and finishing. For rough milling, efficient machining means high stock-removal rates together with close contour approximation and low tool wear. Rough milling is normally carried out layer by layer, i.e. in a 2.SD machining operation with constant depth per cut because the rate of material removal and process reliability are usually highest when this method is used. High-speed cutting (HSC), which has been the subject of extensive university research for far more than ten years, has meanwhile become established as a finishing process in many companies. However, the application of HSC demands the observance of geometric and, above all, technological constraints. A considerable degree of optimization can be achieved when these constraints are applied to rough milling. In the integrated process chain, the CAD/CAM system performs the task of calculating NC programs based on CAD data which meet the requirements posed by rough and finish machining operations. While general interest was focused on the development of CAM strategies for HSC finish machining, advanced development of technology-oriented CAM modules for upstream roughing operations was neglected. The paper at hand deals with the development of a CAM module for rough-machining complex components in die, mould and pattern manufacturing. It provides an insight into the process-technological demands made on HSC operations and their application in rough machining, from which guidelines and requirements on technologically oriented NC functions for CAM software were derived. These encompass both the complete development of an interactive, dialogue-based user guidance function and the algorithmic conversion of the calculation routines. The concept at hand was almost entirely implemented and integrated in the CAD/CAM system developed by Tebis AG, Germany, which was conceived especially for die, mould and pattern manufacturing and is scheduled for introduction to the free market starting in April 2001

    Parametric modelling of APT cutters and accurate calculation of their area moments of inertia

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    Due to cutting forces and the flexibility of the tool and its holder, the tool (or end-mill) deflects when it is engaging with the workpiece; unfortunately, large deflections can cost part accuracy, even break the tool. To produce high-precision parts, it is important to predict the deflections with high fidelity and then greatly reduce them through compensation in CNC tool paths. For this purpose, many research works have been successfully conducted on cutting forces prediction; however, another critical factor, the area moment of inertia of the tool, is always approximated, significantly reducing the accuracy of estimated deflections. The main reason for this is that the 3-D geometric model of end-mills is difficult to construct. To find the moment of inertia, in this work, first, a parametric model of APT cutters has been established and implemented in the CATIA CAD/CAM system by using its API. Then, a system of calculating the area moment of inertia for end-mills is built. Finally, a detailed discussion on the moment of inertia of end-mills is provided, along with comparison of this work with the existing methods. The major contributions of this work include the parametric end-mill modeling, which can automatically render the 3-D geometric model of an end-mill in seconds, and accurate calculation of the moments of inertia of end-mills. This work can be used, together with an existing cutting force calculation method, to accurately predict cutter deflections during milling in order to compensate them in CNC tool paths. It can also provide more precise 3-D solid models of end-mills for machining simulation by using finite element analysis

    Implementation of hierarchical design for manufacture rules in manufacturing processes

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    In order to shorten the product development cycle time, minimise overall cost and smooth transition into production, early consideration of manufacturing processes is important. Design for Manufacture (DFM) is the practice of designing products with manufacturing issues using an intelligent system, which translates 3D solid models into manufacturable features. Many existing and potential applications, particularly in the field of manufacturing, require various aspects of features technology. In all engineering fields geometric modelling wluch accurately represents the shape of a whole engineering component has become accepted for a wide range of applications. To apply DFM rules or guidelines in manufacturing processes, they have to be systematised and organised into a hierarchical rule system. Rules at the higher level of the hierarchical system are applied to more generic manufacturing features, and specific rules are applied to more detailed features. This enables the number of rules and amount of repetition to be minimsed. Violation of the design for manufacture rules in the features, their characteristics and manufacturing capabilities are further examined in this hierarchical system. Manufacturabillty analysis, such as production type, materials, tolerances, surface finish, feature characteristics and accessibility, are also taken into consideration. Consideration of process capabilities and limitations during the design process is necessary in order to minimise production time and as a result, rnanufactunng cost. The correct selection of manufacturing processes is also important as it is related to the overal cost. As a result of this research, a hierarchical design for manufacture rule system is proposed which would aid designers in avoiding designs that would lead to costly manufacturing processes

    Tool path generation for roughing integrally bladed rotors using cup mill cutters

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    Machining of sculptured surfaces -- Manufacturing of integrally bladed rotors -- Motivation -- Objectives and approach -- Thesis structure -- Actual IBR roughing method -- Definition of integrally bladed rotors (IBRs) -- Current IBR roughing tools -- Productivity & cost of actual method -- Point milling -- Flank milling -- New IBRs roughing method -- Compressors machining using annular cutters -- Tool development of IBRs machining with cup mill -- Tool designs -- Sandvik tool performance evaluation -- Productivity and cost evaluation -- Inconel 718 tests -- Program development for IBR machining with cup mill -- Software used (Catia V5 -- VB6) -- Algorithm -- Program -- Smoothing out the tool path -- Complete tool path -- Test & Result for IBR machining with cup mill -- Program simulation in CATIA V5 -- Machining test with the cup mill -- Optimization algorithms
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