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Dynamics of Torsional and Axial Vibrations in Indexable Drills
Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser. (PTW)ORCID-id: 0000-0002-0390-9194
2015 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Drilling is widely used in manufacturing of products which need holes, for example for fluid channels, screws or pins. Depending on application, workpiece material, cutting parameters and economic considerations, different types of drills are employed. Indexable insert drills are types of drills which facilitate inserts to make holes. These types of drills can make high pitch noises due to vibrations. The focus of this thesis is to investigate the mechanism behind these vibrations in order to help reducing the generated noise in the future designs. Primary investigations show that the main mechanism which results the mentioned noise is regenerative chatter vibrations due to axial and torsional flexibilities. There is a gap in modeling of chatter vibrations in indexable drills where loadings and geometries are asymmetrical and due to torsional vibrations, delay terms are variable. The first step of simulating regenerative chatter vibrations in the drill is to model static cutting forces in a reliable way. In this thesis, a model is proposed which is capable of predicting static cutting forces through segmentation of cutting edges. Since, using this model, forces can be calculated separately on each insert, it is possible to consider differences of inserts in estimationof the cutting loads. The obtained loads are used in the chatter simulation.A model is proposed to simulate chatter vibrations by considering axialand angular deflections and the coupling between them. The resulted model isa system of delay differential equations with variable delays. Variations in timedelays, tool jump-outs and backward motions of inserts have been included inthe proposed time-domain simulation. A set of experiments is conducted toverify the model.

sted, utgiver, år, opplag, sider
Trollhättan: University West , 2015. , s. 54
Serie
Licentiate Thesis: University West ; 6
Emneord [en]
Drilling Dynamics, Chatter Vibrations, Indexable Drills, Simulation
HSV kategori
Forskningsprogram
Produktionsteknik
Identifikatorer
URN: urn:nbn:se:hv:diva-8736ISBN: 978-91-87531-23-1 (tryckt)ISBN: 978-91-87531-22-4 (tryckt)OAI: oai:DiVA.org:hv-8736DiVA, id: diva2:875498
Presentation
(engelsk)
Veileder
Tilgjengelig fra: 2015-12-01 Laget: 2015-12-01 Sist oppdatert: 2016-01-11bibliografisk kontrollert
Delarbeid
1. Time-Domain Modeling of Torsional-Axial Chatter Vibrations in Indexable Drills with Low Damping
Åpne denne publikasjonen i ny fane eller vindu >>Time-Domain Modeling of Torsional-Axial Chatter Vibrations in Indexable Drills with Low Damping
2015 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Vancouver: , 2015
Emneord
Drills, chatter vibrations
HSV kategori
Forskningsprogram
Produktionsteknik; TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-8733 (URN)
Konferanse
The 4th International Conference on Virtual Machining Process Technology (VMPT 2015)
Merknad

Ingår i avhandling

Tilgjengelig fra: 2015-12-01 Laget: 2015-12-01 Sist oppdatert: 2019-03-13bibliografisk kontrollert
2. Time Domain Simulation of Chatter Vibrations in Indexable Drills
Åpne denne publikasjonen i ny fane eller vindu >>Time Domain Simulation of Chatter Vibrations in Indexable Drills
2017 (engelsk)Inngår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 89, nr 1-4, s. 1209-1221Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Regenerative chatter vibrations are common in drilling processes. These unwanted vibrations lead to considerable noise levels, damage the quality of the workpiece, and reduce tool life. The aim of this study is to simulate torsional and axial chatter vibrations as they play important roles in dynamic behavior of indexable insert drills with helical chip flutes. While asymmetric indexable drills are not the focal points in most of previous researches, this paper proposes a simulation routine which is adapted for indexable drills. Based on the theory of regenerative chatter vibration, a model is developed to include the asymmetric geometries and loadings that are inherent in the design of many indexable insert drills. Most indexable insert drills have two inserts located at different radial distances, namely central and peripheral inserts. Since the positions of the central and peripheral inserts are different, the displacement and thereby the change in chip thickness differs between the inserts. Additionally, the inserts have different geometries and cutting conditions, e.g., rake angle, coating, and cutting speed, which result in different cutting forces. This paper presents a time-domain simulation of torsional and axial vibrations by considering the differences in dynamics, cutting conditions, and cutting resistance for the central and peripheral inserts on the drill. The time-domain approach is chosen to be able to include nonlinearities in the model arising from the inserts jumping out of cut, multiple delays, backward motions of edges, and variable time delays in the system. The model is used to simulate cutting forces produced by each insert and responses of the system, in the form of displacements, to these forces. It is shown that displacements induced by dynamic torques are larger than those induced by dynamic axial forces. Finally, the vibration of a measurement point is simulated which is favorably comparable to the measurement results.

Emneord
Chatter, Indexable insert drill, Time-domain
HSV kategori
Forskningsprogram
Produktionsteknik; TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-8734 (URN)10.1007/s00170-016-9137-8 (DOI)000394500300097 ()2-s2.0-84979508770 (Scopus ID)
Forskningsfinansiär
Knowledge Foundation
Merknad

Ingår i avhandling från 2015

Funders: Sandvik Coromant

Tilgjengelig fra: 2015-12-01 Laget: 2015-12-01 Sist oppdatert: 2019-05-23bibliografisk kontrollert
3. A Mechanistic Approach to Model Cutting Forces in Drilling with Indexable Inserts
Åpne denne publikasjonen i ny fane eller vindu >>A Mechanistic Approach to Model Cutting Forces in Drilling with Indexable Inserts
2014 (engelsk)Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 24, nr 0, s. 74-79Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Holes are made in many industrial parts that need screws, pins or channels for passing fluids. The general method to produce holes in metal cutting is by drilling operations. Indexable insert drills are often used to make short holes at a low cost. However, indexable drills are prone to vibrate under certain circumstances, causing vibrations that affect tool life. Therefore, a good prediction of cutting-forces in drilling is important to get a good description of the cutting process for optimization of tool body and insert design. Reliable simulations of dynamic forces also aid in prediction of chatter vibrations that have significant effects on the quality of the manufactured parts as well as the tool life. In this paper, a mechanistic approach is used to model the cutting-forces. Cutting-force coefficients are identified from measured instantaneous forces in drilling operations. These coefficients are used for simulating torque around drill-axis, axial force and cutting-forces in the plane perpendicular to drill-axis. The forces are modeled separately for peripheral and central insert, which results in a detailed description of the cutting-forces acting on each insert. The forces acting on each insert are estimated by dividing the cutting edges into small segments and the cutting-forces acting on each segment are calculated. The total forces are predicted by summation of the forces acting on each segment. Simulated torque and forces are compared to measured cutting-forces for two different feeds. A good agreement between predicted and experimental results, especially in torque and axial-force, is observed.

Emneord
Indexable insert drill, Cutting-forces, Mechanistic force model.
HSV kategori
Forskningsprogram
TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-7025 (URN)10.1016/j.procir.2014.07.138 (DOI)2-s2.0-84923168435 (Scopus ID)
Forskningsfinansiär
Knowledge Foundation
Merknad

New Production Technologies in Aerospace Industry - 5th Machining Innovations Conference (MIC 2014)

Tilgjengelig fra: 2014-11-24 Laget: 2014-11-24 Sist oppdatert: 2017-12-05bibliografisk kontrollert

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