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Constructive methods to reduce thermal influences on the accuracy of industrial robots

Procedia Manufacturing 2019年 33卷 19-26页

作者： Christian Mohnke Sascha Reinkober Eckart Uhlmann Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstraße 8-9 10587 Berlin Germany Institute of Machine Tools and Factory Management Pascalstraße 8-9 10587 Berlin Germany

Due to their kinematics and their mobility, industrial robot systems offer a flexible, adaptable basis. An influencing variable, which is particularly relevant for processes with long process times, is the thermal heating and the associated thermal drift of the tool center point. The maximum deviation from the actual nominal position can reach up to 1.5 mm. To counteract these displacements, a cooling strategy or a targeted preheating can be installed. Both possibilities were evaluated under constructive, energetic and economic aspects and implemented on at least one axis of an industrial robot. Furthermore, a structural thermal decoupling and optimized design of the respective components were carried out. The results can help to reduce the influence of thermal heating and the associated thermal drift of the TCP by structural support without using cost-intensive measures with additional hardware and software on external computers for compensating the errors.

关键词： Robot Thermal Error Machining

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Verification of a novel measuring method for determining pre- and postoperative leg length in the context of total hip arthroplasty: a technical feasibility study

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Journal of Medical Engineering and technology 2018年第8期42卷 588-594页

作者： Schmidt, Michael Prietzel, Torsten Wendler, Toni Möbius, Robert Schleifenbaum, Stefan Hammer, Niels Grunert, Ronny ZESBO - Center for Research on Musculoskeletal Systems University of Leipzig Leipzig Germany Department of Orthopaedic Trauma and Plastic Surgery University of Leipzig Leipzig Germany Department of Orthopaedic and Trauma Surgery HELIOS Clinic Blankenhain Blankenhain Germany Department of Anatomy University of Otago Dunedin New Zealand Fraunhofer Institute for Machine Tools and Forming Technology Fraunhofer IWU Dresden Germany

Following total hip arthroplasty (THA), leg length can easily be modified, for example by different-sized endoprosthetic components. Currently, precise reconstruction depends mainly on the assessment of the surgeon. The aim of this study was to determine the accuracy of a new optical measuring system (OMS) using a novel measuring method capable of determining changes in leg length. Measurements with different investigators on an artificial leg and under clinical conditions were carried out. Measurements under clinical conditions were accomplished with a human body donor before and following prosthetic hip implantation. Furthermore, computed tomography (CT) was used to compare the function and the precision of the OMS relating to established measuring methods. The following results were achieved. The overall mean result of preoperative leg length determination by the OMS was 775.3 ± 5.8 mm (CT: 786.4 mm). The overall mean result of postoperative leg length determination by the OMS was 776.9 ± 10.8 mm (CT: 795.0mm). Measurements carried out showed that the novel measuring method works in principle. However, the viable prototype based on it has a lower accuracy compared to CT-based reference measurements, indicating the necessity of integrating more precise hardware. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

关键词： Arthroplasty

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Study on the Influence of the Processing Speed in the Generation of Complex Geometries in Aluminium Matrix Composites by Electrochemical Precision Machining

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Procedia CIRP 2018年 68卷 713-718页

作者： Norbert Lehnert Gunnar Meichsner Matthias Hackert-Oschätzchen André Martin Andreas Schubert Professorship Micromanufacturing Technology Chemnitz University of Technology 09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

Currently, an increasing demand for lightweight materials with a high strength can be observed. Potential materials, which fulfil these requirements, are particle reinforced aluminium matrix composites (AMCs). AMCs consist of an aluminium matrix, which is reinforced by ceramic particles. In a consequence, AMCs offer a strength, which is comparable to steel, along with a density, which is comparable to light metals. In the Collaborative Research Centre SFB 692 at Chemnitz University of technology, AMCs are analysed under different research aspects. One of these aspects is the generation of complex geometries by Electrochemical Precision Machining (PECM). The investigated AMC consists of ENAW 2017, which is reinforced by 10% of SiC-particles. To achieve the desired complex geometry, the dissolution characteristic of the specific AMC was analysed. Furthermore, the achievable surface quality was characterised. Based on these fundamental results, processing strategies for generating complex geometries in AMCs by PECM were derived. In this study, the influence of the PECM processing speed on the resulting complex geometry is investigated. For that purpose, a model geometry based on a retarder was selected and realized. The resulting side gap and the front gap as a function of an increasing processing voltage and an increasing feed rate are presented. It can be stated that the side gap can be reduced by an increase in feed rate.

关键词： Electro chemical machining (ECM) Metal matrix composite Aluminium Silicon carbide

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Derivation of Guidelines for Reliable Finishing of Aluminium Matrix Composites by Jet Electrochemical Machining

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Procedia CIRP 2018年 68卷 471-476页

作者： Norbert Lehnert Matthias Hackert-Oschätzchen André Martin Andreas Schubert Professorship Micromanufacturing Technology Chemnitz University of Technology 09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

The Collaborative Research Centre SFB 692 at Chemnitz University of technology is focused on aluminium-based light-weight materials in safety-related parts and components. One field of activity are aluminium matrix composites (AMCs). Thereby, the manufacturing, the mechanical properties, the economic opportunities and challenges as well as the machinability are investigated. One of the research focusses is the finish-machining of AMCs by Jet Electrochemical Machining (Jet-ECM). Therefore, one objective is to achieve guidelines for reliable machining of AMCs by Jet-ECM. In a first step the dissolution characteristic of EN AW 2017 with 10% of SiC particles, which was manufactured within the SFB 692, was analysed by help of a microcapillary cell, applying a sodium nitrate electrolyte. Furthermore, Jet-ECM was used to generate point erosions using different pH-neutral electrolytes, namely NaNO 3 and NaCl. AMCs made of the aluminium alloy EN AW 2017 with 0%, 5% and 10% SiC particles were machined with a maximal voltage of 25 V. In the current study the parameter field is extended further. The dissolution characteristic by using the pH-neutral electrolyte sodium-bromide is analysed and the voltage range is set to 60 V. Those experiments show, that each electrolyte causes a specific dissolution characteristic. Based on the experimental data, guidelines for a reliable finishing of AMCs by Jet-ECM are derived. The resulting guidelines can be used to predict the depth of the point erosions as function of particle fraction, the applied voltage and the machining time, with respect to the used electrolyte. The statistical evaluation of the guidelines show, that the applied voltage and the machining time are the dominant factors to control the dimensions of the point erosions. Whereas the particle fraction has a minor effect on depth and width.

关键词： Electro chemical machining (ECM) Metal matrix composite Aluminium Silicon carbide

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Ontology-based microservices architecture for industrial assistant systems 12

Ontology-based microservices architecture for industrial ass...

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Smart Systems Integration 2018 - 12th International Conference and Exhibition on Integration Issues of Miniaturized Systems

作者： Singer, Adrian Wenzel, Ken Müller, Jan Langer, Tino Putz, Matthias Digitalization in Production Germany Department Digitalization in Production Germany Automation and Monitoring Germany Head of Division Smart Factory - Digitalization and Automation Germany Institute Scientific Field Machine Tools Production Systems and Machining Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 Chemnitz09126 Germany

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Bio-Intelligent Selective Laser Melting System based on Convolutional Neural Networks for In-Process Fault Identification

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Procedia CIRP 2020年 88卷 612-617页

作者： Roberta Angelone Alessandra Caggiano Roberto Teti Adriaan Spierings Alexandre Staub Konrad Wegener Department of Chemical Materials and Industrial Production Engineering University of Naples Federico II Italy Fraunhofer Joint Laboratory of Excellence on Advanced Production Technology (Fh-J_LEAPT UniNaples) Italy Department of Industrial Engineering University of Naples Federico II Italy inspire AG Innovation centre for additive manufacturing Switzerland Institute of Machine Tools and Manufacturing ETH Zurich Switzerland

This research work focuses on the development of a bio-intelligent additive manufacturing system based on Selective Laser Melting (SLM) technology in the framework of the Biological Transformation in Manufacturing. With the objective to provide the SLM system with cognition, decision making and self-learning capabilities inspired by human intelligence and cognitive skills, a machine learning approach using convolutional neural networks for in-process fault identification based on automatic image processing is presented. An in-process sensor monitoring system based on a camera installed on the SLM machine tool is employed to acquire images of the scanned layers with the final aim to timely identify possible faults and realize an adaptive layer-by-layer control loop in which the process is self-adjusted based on learning.

关键词： Additive manufacturing Selective laser melting Bio-intelligence Convolutional neural networks machine learning Image processing

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Enhancement and analysis of multidimensional characteristic diagrams for correction of TCP-displacements caused by thermal tool displacement

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Procedia CIRP 2018年 77卷 553-556页

作者： Matthias Putz Christian Oppermann Michael Bräunig Fraunhofer-Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Chemnitz University of Technology 09010 Chemnitz Germany

In the present paper former developed characteristic diagram approaches for the correction of thermo-elastic TCP-displacements during cutting processes are extended. Input variables linked with the resulting deformations are estimated by Design of Experiments (DoE). Deformations are computed by means of FEA via the estimation of heat fluxes in the system workpiece – chip – tool – clamping device and the temperature field in tool and clamping device. Multidimensional characteristic diagrams are derived to enable real-time correction of tool paths within the machine tool control. These correction approaches are of crucial importance especially in the field of precision machining and difficult-to-cut material generating large heat amounts. With the obtained correction values the effect of the different cutting parameters on the TCP-displacement is investigated in a sensitivity analysis.

关键词： TCP-displacement Thermal error Characteristic diagramm machine Tool Sensitivity analysis Design of Experiments

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A new simulation and optimization tool for calculating the attenuation of airborne and structure-borne sound of maritime silencers 47

A new simulation and optimization tool for calculating the a...

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47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering, INTER-NOISE 2018

作者： Lindner, Paul Schulze, Christian Hübelt, Jörn Georgi, Tom Troge, Jan Gesellschaft für Akustikforschung Dresden mbH Blumenstraße 80 Dresden01307 Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden01187 Germany

The acoustical impact of silencers is restricted by the influence of structure-borne sound. Thereby, excitation and radiation of structure-borne sound play an important role, as well as its transmission along the silencer system. In the design process of a silencer the influence of structure-borne sound on the damping effect is mostly considered by empirical estimations, which can cause an oversized construction. For calculating structure-borne sound in maritime silencers with their typical large dimensions, the application of statistical methods is a possible problem-solving approach. In this contribution, a new simulation and optimization tool is presented, considering the decreased damping effect of silencers due to structure-borne sound. The tool is based on Statistical Energy Analysis (SEA). Results of analytical and experimental SEA are compared. These results were obtained on downscaled silencers and have been transferred to real maritime silencers. Especially the SEA-parameters loss factor and coupling loss factor, airborne and structure-borne sound energies and the number of relevant modes are considered. Based on the measured damping of a silencer compared with numerical and statistical calculations, the capability for optimizing the design process of large silencers is shown. © INTER-NOISE 2018 - 47th International Congress and Exposition on Noise Control Engineering: Impact of Noise Control Engineering. All rights reserved.

关键词： Damping

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Development of a classification and generation approach for innovative technologies

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Procedia Manufacturing 2018年 21卷 798-805页

作者： A.P. Kuznetsov H.-J. Koriath Moscow State University of Technology “STANKIN” 127055 Moscow Russia Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany

This paper considers the state of the art and analyses five existing classification principles for technological and manufacturing processes aiming at the part and product formation. The proposed energetic-information model describes the generation of technological schemes and processes, based on the system description for structural conversion, transfer and interaction of material, energy and information. Classification principles for technological processes and their structural description generate classes, types and procedures (methods). A generation procedure and mechanism for innovative technological processes is developed. Approved classification of manufacturing processes for DIN8580, NISTIR 7913, according to Todd, Paul De Garmo, by Ashby are particular cases of the proposed classification approach. The proposed approach and process classification system is forming an image of DIN8580. The classification, generation and analysis approach for manufacturing technologies applies for the creation of innovative procedures, manufacturing equipment and systems.

关键词： methods manufacturing processes technology classification

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Target-oriented Analysis of Resource Consumption in Manufacturing Process Chains

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Procedia Manufacturing 2018年 21卷 462-467页

作者： A. Demmer N. Klingbeil F. Klocke M. Putz R. Schmitt T. Vollmer Fraunhofer-Institute for Production Technology IPT Steinbachstrasse 17 Aachen 52074 Germany Fraunhofer-Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 Chemnitz 09126 Germany

Nowadays, manufacturing companies have to view their resource consumption as a cost driver in order to identify efficient and economical processes. Methodologies for investigating, assessing and comparing process chains are vital in order to gain an accurate insight into cost drivers over the course of the entire process chain [1]. Scrutiny of this nature enables cost drivers to be identified via the parameters process time, machine and staff costs in addition to costs related to energy, material and consumables. A review of the usage phase permits elevated costs during manufacture to be justified by reduced costs during operation. The allocation of costs to resources within individual cost-driving process steps ensures target-oriented derivation of improvement measures. The methodology has been designed to serve as basis for production planning, for example, with regard to (energy and resource) efficiency and applied to low-pressure turbine blades made of nickel-base alloys and titanium aluminide. A dedicated analysis of process chain costs provides an insight into the development of individual production costs. This information forms a basis on which to make decisions regarding output quantity or the most appropriate time for investment in new machines. In conjunction with the process chain comparison, this serves as a basis for the integration of the results obtained into a data base which allows the user to select a goal-oriented process chain selection. The data base can provide information regarding the organization of production chains in order to ensure that the product is manufactured accordingly to reduce resources, energy consumption, process times or overall costs.

关键词： Energy efficiency Manufacturing process Production planning

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