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Estimation of Machining System Dynamic Properties - Measurement and Modelling
KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Machine and Process Technology.ORCID iD: 0000-0003-0155-127X
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dynamic characteristics of machining systems are analysed for improved understanding of both structural and process properties. The thesis stresses the use of testing methods under operational like conditions as these are more representative of closed loop systems, such as machining systems, as compared to conventional testing methods.

The test instrument proposed is a contactless excitation and response system, developed for testing of machine tool spindles under load and with rotating spindle. The instrument uses electromagnetic excitation and displacement sensors for analysis of rotating milling tools subject to load. A graphical tool for displaying and analysing rotor displacement was developed in conjunction with this.

A modelling procedure for both off-line and on-line estimation of dynamic properties of mechanical structure and process information is presented. The proposed auto-regressive moving average models enable calculation of operational dynamic parameters and they can be estimated in a recursive manner, thus enabling real-time monitoring. The discrimination between stable and unstable processes, both in turning and milling, was performed by analysing the damping obtained from the operational dynamic parameters.

Place, publisher, year, edition, pages
Stockholm: Kungliga Tekniska högskolan, 2017. , p. 57
Series
TRITA-IIP, ISSN 1650-1888 ; 17-02
Keywords [en]
Machining system, Operational dynamic parameters, Displacement map, Contactless excitation and response system
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
SRA - Production; Production Engineering
Identifiers
URN: urn:nbn:se:kth:diva-204579ISBN: 978-91-7729-323-1 (print)OAI: oai:DiVA.org:kth-204579DiVA, id: diva2:1085330
Public defence
2017-04-28, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
VINNOVA
Note

QC 20170330

Available from: 2017-03-30 Created: 2017-03-28 Last updated: 2017-03-30Bibliographically approved
List of papers
1. Evaluation of tool steel alloy performance in a milling operation through operational dynamic parameters
Open this publication in new window or tab >>Evaluation of tool steel alloy performance in a milling operation through operational dynamic parameters
2017 (English)In: International journal of machine tools & manufacture, ISSN 0890-6955, E-ISSN 1879-2170, Vol. 114, p. 54-59Article in journal (Refereed) Published
Abstract [en]

Dynamic characteristics of machine tools and cutting tools have gained much attention from researchers and industry as it is one of the major factors limiting productivity due to excessive vibrations such as chatter during the cutting process. Numerous factors have to be taken into consideration when selecting material of the cutter body. This paper presents a comparison between two cutter bodies with the same geometry but made out of different alloys. Pre-hardened steel and conventional tool steel were investigated in order to highlight the advantages of selecting correct material to achieve high performance tools with respect of chatter resistance. The experimental part of this paper consists of impact testing, machining tests and surface integrity measurements. Operational dynamic parameters obtained through auto-regressive moving average model estimates from machining tests under stable and unstable conditions was used to characterise the performance. The findings are in correlation with material damping research and chatter analysis, thus giving a strong coupling to material selection in tool holders for enhanced process stability. The research also shows that operational dynamic properties obtained through indirect measurements is a valuable tool for process stability characterisation.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Cutting stability, Machining performance, Pre-hardened steel
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Production Engineering; SRA - Production
Identifiers
urn:nbn:se:kth:diva-200743 (URN)10.1016/j.ijmachtools.2016.12.009 (DOI)000394072500005 ()2-s2.0-85007356254 (Scopus ID)
Projects
FFI COMPIT
Funder
VINNOVA
Note

QC 20170202

Available from: 2017-02-02 Created: 2017-02-02 Last updated: 2017-11-29Bibliographically approved
2. Analysis of stationary displacement patterns in rotating machinery subject to local harmonic excitation
Open this publication in new window or tab >>Analysis of stationary displacement patterns in rotating machinery subject to local harmonic excitation
2017 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 389, p. 224-235Article in journal (Refereed) Published
Abstract [en]

Rotor vibration and stationary displacement patterns observed in rotating machineries subject to local harmonic excitation are analysed for improved understanding and dynamic characterization. The analysis stresses the importance of coordinate transformation between rotating and stationary frame of reference for accurate results and estimation of dynamic properties. A generic method which can be used for various rotor applications such as machine tool spindle and turbo machinery vibration is presented. The phenomenon shares similarities with stationary waves in rotating disks though focuses on vibration in shafts. The paper further proposes a graphical tool, the displacement map, which can be used for selection of stable rotational speed for rotating machinery. The results are validated through simulation of dynamic response of a milling cutter, which is a typical example of a variable speed rotor operating under different load conditions.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Rotor dynamics, Displacement map, Milling
National Category
Applied Mechanics
Research subject
Engineering Mechanics; SRA - Production
Identifiers
urn:nbn:se:kth:diva-198179 (URN)10.1016/j.jsv.2016.11.017 (DOI)2-s2.0-85002535452 (Scopus ID)
Projects
VINNOVA - FFI COMPIT
Funder
VINNOVA, G62250
Note

QC 20161214

Available from: 2016-12-13 Created: 2016-12-13 Last updated: 2017-11-29Bibliographically approved
3. Control of milling process dynamics through a mechatronic tool holder with purposely designed Joint Interface
Open this publication in new window or tab >>Control of milling process dynamics through a mechatronic tool holder with purposely designed Joint Interface
2015 (English)In: 2015 10th International Symposium on Mechatronics and its Applications (ISMA), Institute of Electrical and Electronics Engineers (IEEE), 2015Conference paper, Published paper (Refereed)
Abstract [en]

Machine tool joints have significant influence on the dynamic characteristics of the machine tool and therefore on the response of the machining system to excitations from the cutting process. In cases of unstable response, generally described as chatter, surface quality of a machined workpiece and tool life deteriorate significantly. This paper presents a novel way of exploiting joints in order to control the dynamic response of the system, by integrating a mechatronic tool holder (Joint Interface Module - JIM) in the machine tool. This system has a purposely designed joint interface with controllable natural characteristics (stiffness and damping). These characteristics are controlled by altering the applied pre-load on the internal joint interface of the tool holder. The preload on the joint interface is controlled by pneumatic means. In doing so, a milling process during which the stability limit was exceeded became stable during the machining process, without alteration of the process parameters.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2015
Keywords
Cutting, Cutting tools, Machine tools, Milling (machining), Dynamic characteristics, Internal joints, Joint interfaces, Machining Process, Machining systems, Milling process, Process parameters, Stiffness and damping
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-191765 (URN)10.1109/ISMA.2015.7373475 (DOI)000380519100021 ()2-s2.0-84964923554 (Scopus ID)978-1-4673-7797-3 (ISBN)
External cooperation:
Conference
10th International Symposium on Mechatronics and its Applications, ISMA 2015; Sharjah; United Arab Emirates; 8 December 2015 through 10 December 2015
Note

QC 20160906

Available from: 2016-09-06 Created: 2016-09-02 Last updated: 2017-03-28Bibliographically approved
4. Suppressing tool chatter with novel multi-layered nanostructures of carbon based composite coatings
Open this publication in new window or tab >>Suppressing tool chatter with novel multi-layered nanostructures of carbon based composite coatings
Show others...
2015 (English)In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 223, p. 292-298Article in journal (Refereed) Published
Abstract [en]

Multi-layered nanostructured Cu and Cu-CNx composites synthesized by plasma-enhanced chemical vapour deposition were applied in the clamping area of a milling tool to suppress regenerative tool chatter. Scanning electron microscopy analysis showed a multi-layered nanostructure with excellent conformality, i.e. coating is not only uniform on planar surfaces but also around corners of the substrate. Cu:CuCNx nanostructured multilayers with thicknesses of approximately 0.5:1.6 mu m were obtained. With a diameter of 20 mm, the milling tool performed slotting processes at an overhang length of 120 mm. Modal analysis showed that a coating, with a thickness of approximately 300 mu m, can add sufficient damping without losing stiffness of the tool, to increase the critical stability limit by 50% or 100% depending on cutting direction.

Keywords
Milling, Tool regenerative chatter, Metal matrix composites, Nano-structures, Internal friction damping, Plasma enhanced chemical vapour deposition (PECVD)
National Category
Production Engineering, Human Work Science and Ergonomics Nano Technology Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-170666 (URN)10.1016/j.jmatprotec.2015.03.043 (DOI)000356106600031 ()2-s2.0-84929497633 (Scopus ID)
Funder
EU, European Research Council, 260048, 608800
Note

QC 20150707

Available from: 2015-07-07 Created: 2015-07-03 Last updated: 2017-12-04Bibliographically approved
5. Operational Modal Analysis During Milling Of Workpiece, Fixed On A Stiffness Controllable Joint
Open this publication in new window or tab >>Operational Modal Analysis During Milling Of Workpiece, Fixed On A Stiffness Controllable Joint
2013 (English)In: Journal of Machine Engineering, ISSN 1895-7595, Vol. 13, no 2, p. 69-78Article in journal (Refereed) Published
Abstract [en]

Vibration in metal cutting processes has been studied to a great extent resulting in for instance stability lobe diagrams under which stable machining parameters can be selected. One limitation of accurately estimated stability diagrams is the change in process and dynamic characteristics of the machine tool under operation. The machine tool dynamic response is often analysed with experimental modal analysis under off operational conditions. One drawback with this approach is the large number of measurements required to fully describe a machine tool and workpiece in different positions and time of machining. Another drawback is that the change of dynamic characteristics under operation is excluded. Operational modal analysis has been applied in machining under different conditions resulting in successfully improved stability lobe prediction. This research includes operational modal analysis of the workpiece, fixed on a stiffness controllable joint and stability prediction to stress the importance of various machining conditions.

Place, publisher, year, edition, pages
Wroclaw, Poland: Wroclawska Rada Federacji Stowarzyszen Naukowo-Technicznych NOT, 2013
Keywords
machine tool, operational modal analysis, machining stability
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-133565 (URN)
Funder
VinnovaXPRES - Initiative for excellence in production research
Note

QC 20140124

Available from: 2013-11-06 Created: 2013-11-06 Last updated: 2017-03-28Bibliographically approved
6. Extending stability limits by designed-in damping
Open this publication in new window or tab >>Extending stability limits by designed-in damping
2013 (English)In: Journal of Machine Engineering, ISSN 1895-7595, Vol. 13, no 1, p. 37-48Article in journal (Refereed) Published
Abstract [en]

With advances in material technology come challenges to productivity. New materials are, in fact, more difficult to machine with regards to tool wear and especially machine tool stability. This paper proposes to extend the stability limits of the machining system by enhancing the structure’s damping capability. The aim of the research work presented here is to introduce a unified concept based on the distribution of damping within the machining system components exploiting the dynamic properties of the existing joints. To maintain a high level of static stiffness, it was chosen to adapt hydrostatic clamping systems to the tools. Damping is designed in the structure via high damping interfaces (HDI), intentionally introduced interfaces where the damping ratio is enhanced by introduction of viscoelastic polymer metal composites between the two metallic surfaces composing the interface. In this paper HDI are introduced at two joints, between tool and turret and between turret and lathe. The tests show that the designed-in damping is effective and allows extending the stability limits of the machining system. The implementation of designed-in damping allows the end user to select the most suitable parameters in terms of productivity avoiding the hassle of tuning the devices, having to acquire a deep knowledge in structural dynamics or having to use additional control systems. In addition to this, the enhanced machine tool system becomes less sensitive to stability issues provoked by difficult-to-machine materials or even fluctuations of the work material properties that might occur in everyday production processes.

Place, publisher, year, edition, pages
Wroclaw: Editorial Institution of the Wroclaw Board of Scientific Technical Societies Federation NOT, 2013
Keywords
high damping interface, cutting stability, operational dynamic properties, machine tool design
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-120464 (URN)
Projects
FFI Robust MachiningFFI COMPIT – Capability of Machining Systems and Performance Improvement Technologies
Funder
XPRES - Initiative for excellence in production researchVinnova
Note

QC 20130814

Available from: 2013-04-08 Created: 2013-04-08 Last updated: 2017-03-28Bibliographically approved
7. Contactless excitation and response system for analysis of high precision rotor dynamic properties
Open this publication in new window or tab >>Contactless excitation and response system for analysis of high precision rotor dynamic properties
2013 (English)In: Laser Metrology and Machine Performance X: LAMDAMAP 2013 / [ed] Prof. Liam Blunt & Dr. Wolfgang Knapp, Bedfordshire, UK: euspen , 2013, p. 150-156Conference paper, Published paper (Refereed)
Abstract [en]

The spindle system is a critical part of a machine tool structure and its dynamic properties are important for the performance of the whole machining system. Currently the only way to extract the dynamic properties of a given structure is via experimental modal analysis. This approach, however, can only be employed on idle systems and is performed with the assumption that the dynamics of a system are independent of rotational speed. The latter assumption cannot be applied to spindle systems. This paper introduces a novel testing system for analysing machine tool spindles dynamic properties, consisting of real-time recursive estimation of modal and operational dynamic parameters, employed alongside a contactless excitation and response system. The presented approach allows analysing the spindle system condition and dynamic properties not only at discrete rotational speed intervals but also during continuous sweep of rotational speed.

Place, publisher, year, edition, pages
Bedfordshire, UK: euspen, 2013
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-120465 (URN)2-s2.0-84908266209 (Scopus ID)978-0-9566790-1-7 (ISBN)
Conference
Laser Metrology, Machine tool, CMM and Robotic Performance, Lamdamap 10th International Conference and Exhibition; Kavli Royal Society International Centre, Buckinghamshire, UK, March 20-21, 2013
Projects
FFI COMPIT – Capability of Machining Systems and Performance Improvement Technologies
Funder
XPRES - Initiative for excellence in production researchVinnova
Note

QC 20130823

Available from: 2013-04-08 Created: 2013-04-08 Last updated: 2017-03-28Bibliographically approved
8. Improvement of Gear Cutter Dynamics by Use of Acoustic Imaging and High Damping Interface
Open this publication in new window or tab >>Improvement of Gear Cutter Dynamics by Use of Acoustic Imaging and High Damping Interface
2012 (English)In: 3rd CIRP Conference on Process Machine Interactions / [ed] Shamoto, E, 2012, p. 17-21Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a study where acoustic imaging technology was employed for problem identification and high damping interfaces (HDI) were implemented in the machine tool structure to improve performance of process machine interaction, in bevel gear cutting, in terms of resistance to instability. Chatter marks at the gear root and tool fracturing represent a serious and widespread problem in the studied process. The acoustic image approach showed good agreement with modal analysis and also allowed to identify the chatter frequency. Once identified the problem, the paper also presents a novel approach for improving resistance to cutting instability by implementing HDI in the structure. The HDI consists of a viscoelastic composite material and is used to damp out the stick blade motion relative to the clamp block by transformation of vibratory energy, into heat. The primary contributions of this paper are the introduction of acoustic imaging for identification of chatter in gear cutting and employment of HDI for performance improvement for rotating tools.

Series
Procedia CIRP, ISSN 2212-8271 ; 4
Keywords
Gear cutter, Testing, High Damping Interface, Acoustic Imaging
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-119570 (URN)10.1016/j.procir.2012.10.004 (DOI)000315024500003 ()2-s2.0-84883854848 (Scopus ID)
Conference
3rd CIRP Conference on Process Machine Interactions (PMI), OCT 29-30, 2012, Nagoya, Japan
Funder
XPRES - Initiative for excellence in production research
Note

QC 20130318

Available from: 2013-03-18 Created: 2013-03-18 Last updated: 2017-03-28Bibliographically approved
9. Evaluation and Representation of Machine tool Deformations
Open this publication in new window or tab >>Evaluation and Representation of Machine tool Deformations
2011 (English)In: Journal of Machine Engineering, ISSN 1895-7595, Vol. 11, no 4, p. 118-129Article in journal (Refereed) Published
Abstract [en]

This paper presents a novel test concept for the evaluation of the accuracy of NC machine tools. The evaluation of machine tools deformations is performed by help of a device similar to the double ball bar (DBB) with the difference that an adjustable load generated by the device can be applied between spindle nose and machine tool table. This load eliminates the play existing in machine tool joints, thus reproducing the testing conditions that exist during machining. Collected data are used to plot diagrams displaying characteristic aspects of achine tool performance and a number of key figures such as static stiffness may be etermined. The data can also be used for trend analysis; to predict any accuracy deviations, and further to conduct preventive maintenance instead of emergency calls. The determined static behaviour could also be used to improve digital models for process simulations and compensation of errors that are caused by deflection.

Place, publisher, year, edition, pages
Wroclaw: Editorial Institution of the Wroclaw Board of Scientific Technical Societies Federation NOT, 2011
Keywords
machine tool, testing, deformation, static stiffness, circular test, loaded double ball bar
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-105190 (URN)
Funder
XPRES - Initiative for excellence in production research
Note

QC 20130123

Available from: 2012-11-18 Created: 2012-11-18 Last updated: 2017-03-30Bibliographically approved

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Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
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Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
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Output format
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