An investigation into the influence of helix angle on the torque-thrust coupling effect in twist drills

Narasimha, K. Rama; Osman, M. O. M.; Chandrashekhar, S.; Frazão, João

doi:10.1007/bf02601495

Cited by 17 publications

(12 citation statements)

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“…Natali and colleagues suggested the optimal helix angle for surgical drill-bits to be approximately 36° (Natali, Ingle et al 1996), actually rendering it a fast helix. The helix angle of a drill-bit has implications for both rake angle and torsional rigidity (Narasimha, Osman et al 1987) but has little effect on the maximal temperature elevation (Davidson and James 2003). Narasimha and co-workers (Narasimha, Osman et al 1987) demonstrated that torsional rigidity varies parabolically with helix angle, reaching a maximum at approximately 28˚.…”

Section: Anatomy Of a Drill-bitmentioning

confidence: 99%

“…The helix angle of a drill-bit has implications for both rake angle and torsional rigidity (Narasimha, Osman et al 1987) but has little effect on the maximal temperature elevation (Davidson and James 2003). Narasimha and co-workers (Narasimha, Osman et al 1987) demonstrated that torsional rigidity varies parabolically with helix angle, reaching a maximum at approximately 28˚. They suggested that this may be the reason for the choice of this angle across a wide range of drills used for a multitude of purposes.…”

Section: Anatomy Of a Drill-bitmentioning

confidence: 99%

“…The grinding of flutes into a solid rod (known in machining terms as a blank) to produce a drill-bit significantly alters both the rotational and bending stiffness properties. In the presence of excessive driving torques a drill bit can unravel (Narasimha, Osman et al 1987), but this is rarely reported complication in the orthopaedic literature. Drill-bits are routinely subjected to bending loads, such as those depicted in Figure 6.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

See 2 more Smart Citations

Drilling of Bone: Practicality, Limitations and Complications Associated with Surgical Drill-Bits

Bertollo¹,

Walsh²

2011

Biomechanics in Applications

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Section: Anatomy Of a Drill-bitmentioning

confidence: 99%

Section: Anatomy Of a Drill-bitmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Drilling of Bone: Practicality, Limitations and Complications Associated with Surgical Drill-Bits

Bertollo¹,

Walsh²

2011

Biomechanics in Applications

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“…It is important to a drill designer/user to understand to what extent this compensation take place and how the design parameters of a twist drill affect this compensation. Narasimha et al [4] proposed to assess torque/thrust coupling using the following coupling matrix:…”

Section: Axial Force (Thrust)-torque Couplingmentioning

confidence: 99%

Straight Flute and Twist Drills

2010

Springer Series in Advanced Manufacturing

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This chapter discusses classification, geometry, and design of straight flute and twist drills. It argues that the design, manufacturing, and implementation practices of drills are lagging behind the achievements in the tool materials, powerful high-speed-spindles rigid machines, and high-pressure MWF (coolant) supply. Although the wide availability CAD design tool and CNC precision grinding machines make it possible to reproduce any drill geometry, have not many new drill designs become available recently. The chapter points out that the prime objective of the drilling system is an increase in the drill penetration rate, i.e., in drilling productivity as the prime source for potential cost savings. As the major problem is in understanding particularities of drill geometry and its components, this chapter walks the reader from simple concepts starting from the basic terminology in drill design and geometry to the most complicated concepts in the field, keeping the context to the simplest possible fashion and providing practical examples. It provides an overview of important results concerning drill geometry and synthesizes the most relevant findings in the field with the practice of tool design. Geometry of Single-point Turning Tools and DrillsChisel edge angle -the angle included between the chisel edge and the cutting lip, as viewed from the end of the drill. Clearance -the space provided to eliminate undesirable contact (interference) between the drill and the workpiece. Cutter sweep -the section formed by the tool used to generate the flute in leaving the flute. Cutting tooth -a part of the body bounded by the rake and flank surfaces and by the land. Double margin drill -a drill whose body diameter clearance is produced to leave two margins on each land and is normally made with margins on the leading edge and on the heel of the land. Drill diameter -The diameter over the margins of the drill measured at the periphery corners. Flute length -the length from the periphery corner of the lips to the extreme back end of the flutes. It includes the sweep of the tool used to generate the flutes and, therefore, does not indicate the usable length of flutes. Flutes -helical or straight grooves cut or formed in the body of the drill to provide cutting lips, to permit removal of chips, and to allow cutting fluid to reach the cutting lips.Galling -an adhering deposit of nascent work material on the margin adjacent to the periphery corned of the cutting edge. Hill -the trailing edge of the land. Helix angle -the angle made by the leading edge of the land with the plane containing the axis of the drill. Land -the peripheral portion of the cutting tooth and drill body between adjacent flutes. Land clearance -see preferred term body diameter clearance. Land width -the distance between the leading edge and the heel of the land measured at right angles to the leading edge.

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“…Chatter can happen due to torsional, axial, and bending deflections of the drill body, and the mechanism of these chatter vibrations has been investigated in the past by several researchers. While the variation of the thrust force changes the length of the drill, torque variations also change the length of the drill due to helical geometry of chip flutes [15]. Changes in the length of the drill affect the chip thickness and thus the forces acting on the drill [16,17].…”

Section: Introductionmentioning

confidence: 99%

Time domain simulation of chatter vibrations in indexable drills

Parsian

Magnevall

Eynian

et al. 2016

Int J Adv Manuf Technol

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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.

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An investigation into the influence of helix angle on the torque-thrust coupling effect in twist drills

Cited by 17 publications

References 1 publication

Drilling of Bone: Practicality, Limitations and Complications Associated with Surgical Drill-Bits

Drilling of Bone: Practicality, Limitations and Complications Associated with Surgical Drill-Bits

Straight Flute and Twist Drills

Time domain simulation of chatter vibrations in indexable drills

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