Andreas Nestler

Complete swept volume generation, Part I: Swept volume of a piecewise C1-continuous cutter at five-axis milling via Gauss map

In this paper, we present a methodology to generate swept volume of prevailing cutting tools undergoing multi-axis motion and it is proved to be robust and amenable for practical purposes with the help of a series of tests. The exact and complete SV, which is closed from the tool bottom to the top of the shaft, is generated by stitching up envelope profiles calculated by Gauss map. The novel approach finds the swept volume boundary for five-axis milling by extending the basic idea behind Gauss map. It takes piecewise C^1-continuous tool shape into account. At first, the tool shape is transformed from Euclidean space into Tool map (T-Map) on the unit sphere and the velocity vector of a cutter is transformed into Contact map (C-Map) using Gauss map. Then, closed intersection curve is found between T-Map and C-Map on the Gaussian sphere. At last, the inverse Gauss map is exploited to get envelope profile in Euclidean space from the closed curve in the range. To demonstrate its validity, a cutting simulation kernel for five-axis machining has been implemented and applied to mold and die machining.

Use of agents and neural networks for acquisition and preparation of distributed NC information to support NC planning

SPEP-NC information offers new possibilities for object-oriented data management. A strong need for high information content and the increasing object-oriented CAM software requires a new information level for preparation and execution tasks in part manufacturing. This paper describes applications of different intelligent methods especially to support distributed technological data management. The problem of current technological databases will be solved with the help of agent technology and machine learning for distributed information on the shop floor and in planning departments. The authors introduce a combination of agent-based organization and self-learning of feature-based technological information. The prototype includes three components for coordination, data acquisition and preprocessing of technological information to assist human engineers in planning and manufacturing.

Mechanistic Model Based on the Actual Removal Volume during Simultaneous Five-Axis Milling

In this paper we present a novel mechanistic model of cutting process of the cylindrical tool by using the actual removal volume per tooth via NC simulation. The simulation kernel enables “virtually” cutting the workpiece in milling process per NC code, as well as calculating the removal volume per tooth which leads to predict the actual cutting force during simultaneous five-axis machining. Combined with the material removal simulation, the advanced mechanistic process model, which can enable the prediction of the cutting force and adjust the trajectory velocity of the cylindrical tools undergoing five-axis movement, is presented by applying the line integral along the cutting edge and taking the rake angle and cutting edge roundness into consideration. The novel methodology to adjust the cutting force by prevailing cutting tools undergoing multi-axis motion is to be validated by experiment and integrated into tool path planning systems.

Influence of Material and Constitutive Models on Friction Analysis for Modelling in Machining Cellular Metal Structures

The selection of an adequate friction model is an important aspect inthe finite element modeling of machining. Previously, different friction modelshave been compared, but the influence of the constitutive model or theworkpiece material have not been considered. This article focuses on theinfluence of the material and the constitutive model on the evaluation of thefriction model in machining. Numerical experiments are performed on threedifferent materials using different constitutive models. For every combinationof material and constitutive model, several simulations using different Coulombcoefficients, but the same cutting parameters, are performed. Several variablesare evaluated: cutting force, shear plane angle, chip-tool contact length,maximum temperature and maximum stress. The results reveal that the workpiecematerial plays an important role in the evaluation of the friction model. Theyalso show that there is significant influence from the constitutive models oncontact length, curvature ratio and chip thickness.

Process based analysis of manually controlled drilling processes for bone

The machining operation drilling is part of the standard repertoire for medical applications. This machining cycle, which is usually a multi-stage process, generates the geometric element for the subsequent integration of implants, which are screwed into the bone in subsequent processes. In addition to the form, shape and position of the generated drill hole, it is also necessary to use a technology that ensures an operation with minimal damage. A surface damaged by excessive mechanical and thermal energy input shows a deterioration in the healing capacity of implants and represents a structure with complications for inflammatory reactions. The resulting loads are influenced by the material properties of the bone, the used technology and the tool properties. An important aspect of the process analysis is the fact that machining of bone is in most of the cases a manual process that depends mainly on the skills of the operator. This includes, among other things, the machining time for the production of a dr...

Investigation of a carbon fibre-reinforced plastic grinding wheel for high-speed plunge-cut centreless grinding application

High-speed plunge-cut centreless grinding opens up enormous potential for the manufacturing of difficult-to-machine materials and to improve the surface quality while reducing the grinding forces. For this investigation, a new grinding wheel base body of carbon fibre-reinforced plastic (CFRP) was developed to achieve grinding wheel speeds up to 150 m/s in plunge-cut centreless grinding of hardened shafts. For evaluation of the performance characteristics, the grinding forces and the surface quality of different grinding tools were detected. These experiments were conducted using a newly developed measuring system to analyse the grinding forces in the workrest blade. The experimental results are described and discussed in this article.

Methodological Issues in Support of Selected Tasks of the Virtual Manufacturing Planning

For virtual production planning a wide variety of tools are already in use. These tools mainly focus at just one methodological aspect. To increase the scope and utility value for process planning, several methodological aspects need to be combined in one single tool. The technological representation of the different aspects usually requires the application of various simulation models beside common data models. In particular, the combination of discrete and continuous time and spatial variables is elaborated.

Neural network based application and data management for cutting values

The manufacturing processes have to guarantee a flexible, high quality production at low cost. In order to fulfil the demands, intelligent information systems are required with special respect to the technology data type. A central point of technological data is the cutting values, i.e. feed and speed. The high speed milling process is one of the newly established processes with the need to set the optimum cutting parameters. The rapid development of advanced materials, tools etc. the results of a recent project* to solve cutting parameter generation problems by means of neural network, mathematical model and technology database system.