A. Sadek 2 1 and Helmi Attia 1,2 - P · PDF fileA. Sadek 2, M. Meshreki 1 and Helmi Attia 1,2...

Advanced Material Removal Program

Wiener Produktionstechnik KongressVienna, May 7-8, 2014

A. Sadek2, M. Meshreki1 and Helmi Attia1,2

1Aerospace Structures, Materials and Manufacturing, National Research Council of Canada (NRC)

2Department of Mechanical Engineering, McGill UniversityMontreal, Quebec, Canada

Email: [email protected] / [email protected]

McGill

Advanced Material Removal Program McGill

Outline

o Introduction.o Research objectives. o Mechanics of the vibration-assisted Drilling (VAD) process.

Mechanism of drilling force reduction. Cutting energy generation and dissipation.

o Experimental work: set-up and test matrix.o Characterization and optimization of the VAD process:

Axial drilling forces and torques. Cutting temperature. Quality attributes and machinabilty maps.

o VAD force prediction model.o Concluding Remarks.

McGill


DelaminationMost Serious Damage Type

DelaminationMost Serious Damage Type

Thermal DamageMatrix Burnout

Thermal DamageMatrix Burnout

Low Productivity

Low Productivity

Poor Cutting(Fiber Fuzziness)

Poor Cutting(Fiber Fuzziness)

Tool rotate around its axis at an eccentric distance from the axis of the hole

Eliminate Dwell of Stationary Drilling

Tool Center

Eliminate Dwell of Stationary Drilling

Tool Center

Cyclic Engagement and Disengagement

of Tool

Cyclic Engagement and Disengagement

of Tool

Reduce Thrust Forces

Reduce Thrust Forces

Orbital DrillingOrbital Drilling

Vibration Assisted Drilling (VAD)

Vibration Assisted Drilling (VAD)

Superimposed axial vibratory motion over the conventional feed motion

Eliminate / minimize

Delamination

Eliminate / minimize

Delamination

Reduce Temperature

Reduce Temperature

Low ProductivityLow Productivity

Reduce axial Feed

Reduce axial Feed

Cutting/ Friction Temperature RiseCutting/ Friction Temperature Rise

Excessive Drilling Forces

Excessive Drilling Forces Intermittent

Cutting Techniques

Intermittent Cutting

Techniques Cooling EffectCooling Effect

Reduce Cutting Speed

Reduce Cutting Speed

Introduction

• Aerospace, automotive, marine, and construction applications. • Drilling for mechanical fastening of of hybrid material stacks,

and for weight reduction.• Machining-induced defects of CFRP (delamination, thermal

damage, fiber pull-out, geometric errors, roughness).

LF/HA: Frequency < 100 HzAmplitude:25<A<800 mm

HF/LA (with IFT): Frequency > 1000 HzAmplitude: A < 20 mm


Objectives

The main objectives of this investigation are: Analyzing the mechanics of force and temperature reduction

during the vibration assisted drilling (VAD) of FRPs. Developing machinability hole quality maps to characterize and

optimize the multi-dimensional VAD process parameters, for a given tool/workpiece materials.

Conceptual development of a VAD predictive force model that can deal with different process variables.


P1: Max separation(initial axial step)

Feed

E2 E1

Tool-workpiece interaction

P3: Max separation

(new axial step)

p-p Amplitude

P2: Max engagement

DOC: Depth of Cut

E1 mean path

E2 mean path

Surface formed by E2


Max DOCCylindrical Hole (Conventional)

Inst DOC d(t)

Min DOC

Hole opened (Vibrating Tool)



-0.07

-0.06

-0.05

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

-1E-15

0.1

0.2

5 7 9 11 13 15

DO

C (m

m)

Posi

tion

(mm

)

Angular position (x π)

E2 E1 DOC

0.0

Engagement

Separation



DOC

Axi

al P

ositi

on (m

m)

Angular Position (x p)

DO

C (m

m)

P1 P3P2

Amplitude, Frequency ratio DOC Frequency Engagement period. (wm / wT) phase difference f.

-0.07

-0.06

-0.05

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

-1E-15

0.1

0.2

5 7 9 11 13 15

DO

C (m

m)

Posi

tion

(mm

)

Angular position (x π)

E2 E1 DOC

0.0



DOC

Axi

al P

ositi

on (m

m)

Angular Position (x p)

DO

C (m

m)

P1 P3P2

Heat Generation

Heat Dissipation

Mechanics of VAD- Effect of A and wT


-0.4

-0.2

0

0.2

0 5 10

Position(m

m)

Angularposition (xπ)

D2 D1 DOC

-0.4

-0.2

0

0.2

0 5 10

Position(m

m)


D2 D1 DOC

-0.4

-0.2

0

0.2

0 5 10

Position(m

m)


D2 D1 DOC

-0.4

-0.2

0

0.2

0 5 10

Position(mm)


D2 D1 DOC

φ

Mechanics of VAD- Effect of A and wm

-0.4

-0.2

0

0.2

0 5 10

Position(m

m)


D2 D1 DOC

-0.4

-0.2

0

0.2

0 5 10

Position(m

m)


D2 D1 DOC

φ

Frequency A

mpl

itude

Formed chip profile

φ

DOC

Engagement Period (t) As Frequency

Phase shift “φ”Period (t) DOC

D Frequency Phase shift “φ” Period (t) DOC


Cutting Energy Generation and Dissipation w

As `n` and `g` increase, Re reaches a critical value; 3Dlaminar flow Taylor vortices.Recr can be achieved in LFHA-VAD.

Conical gaps formed by the drill (2q ~ 120o) has the same flow pattern as that between flat discs.

Taylor vortices


Re, n

0 50 100 150 200 250

0

25

50

75

100

125

150

0

5

10

15

20

0 0,05 0,1 0,15

Air gap width g (mm)

Coef

ficie

nt o

f hea

t tra

nsfe

r in

the

gap

h g(W

/m2 K

Normalized air gap width G (G=g/r)

Re=5.49 E2(n=12,000 rpm)

Re=4.58 E2(n=10,000 rpm)

Re=3.66 E2(n=8,000 rpm)

Re=2.75 E2(n=6,000 rpm)

Nus

selt

Num

ber N

u

Cutting Energy Generation and Dissipation

Re = wR2/n=2p n r2/60 n

Nu = hg R/ka = f{Re,G}

w As `n` and `g`

increase, Re reaches a critical value; 3Dlaminar flow Taylor vortices.Recr can be achieved in LFHA-VAD.

Conical gaps formed by the drill (2q ~ 120o) has the same flow pattern as that between flat discs.

These vortices enhance the CHT hg.

Taylor vortices Min. CHT: G~0.02 (g~ 35 mm); less mass of cooling air. Maxi. CHT: G~ 0.06 (g ~ 115 mm). CHT is reduced for G > 0.06 , due to decoupling effect. Enhancement in CHT with low frequency vibration in the

range of 40-120 Hz.


Heat Transfer-Sensitivity Analysis (FDM)

Cutting Energy Generation and Dissipation

A simple axi-symmetrical FD transient HT model. Boundary conditions:• Cutting energy and heat dissipation

during half of the vibration cycle.• hg= f {Re,G}.

0

100

200

300

400

500

600

0 0,05 0,1 0,15 0,2 0,25 0,3

Tem

pera

ture

Tb

(oC

)

Time (s)

VAD

Conventional

In VAD: Cooling effect of hg + not enough time for the cutting energy to propagate into the tool and the workpiece materials.

The cooling of the tool by the air flow in the conical gap causes the fluctuation in ‘Tb’ in VAD by >100 K.

The maximum temperature of the tool base ‘Tb’ in VAD is less than conventional drilling by more than 100 K.

The rotational speed has a strong effect on the heat dissipation.


Tool tip

Mid-point of the cutting edge

600

650

700

750

800

850

900

1,7 1,75 1,8 1,85

Tem

pera

ture

(°C)

Time (s)

CONV-edgeCONV-tip

VAD-edge

VAD-tip

Temperature variation in VAD ~ 20 K (tool tip) and ~120 K (mid-point of the edge).

Tool tip temperature at exit in VAD is ~ 100 K less than conventional drilling.

The maximum temperature at the mid-point of the edge, in VAD is ~ 20-80 K less than conventional drilling.

VAD: freq = 30 Hz, A = 400 mm, n=2,500 rpm, f=150 mm/min.

Drilling of Ti6Al4V using carbide tool; m=0.3,

Cutting Energy Generation and Dissipation 3D HT FEM of VAD and Conventional Drilling of Ti

Conventional drilling

VAD


Experimental Set-upMachining center: Makino A88

Spindle speed: 18,000 rpm, max feed rate: 50 m/min, power: 50kW.

Force measurement: 6-component Kistler dynamometer (model: 9255B).

A FLIR ThermoVision A20M Infrared camera at the hole exits (εtool=0.34), (error=± 5%).

The LF/HD VAD modulation was provided by a Brüel & Kjaer (B&K) 4805 electro-magnetic shaker, and controlled by a (B&K) 1050 vibration exciter control unit.


Experimental Set-upMachining center: Makino A88

Spindle speed: 18,000 rpm, max feed rate: 50 m/min, power: 50kW.

Force measurement: 6-component Kistler dynamometer (model: 9255B).

A FLIR ThermoVision A20M Infrared camera at the hole exits (εtool=0.34), (error=± 5%).

The LF/HD VAD modulation was provided by a Brüel & Kjaer (B&K) 4805 electro-magnetic shaker, and controlled by a (B&K) 1050 vibration exciter control unit.

The measured force signals were rectified via a dynamic model of the VAD system to filter signal distortions introduced by the system dynamics. (error ± 12.5%).

M1

K1

C1

M2

K2

C2

M3

K3

C3

M4

K4

C4

Work- Shaker

External Force

X1

Dynobaseplate

Dynofaceplate

X2X3X4

piece

-80

-40

0

40

80

0 0,1 0,2 0,3

Axi

al F

orce

(N)

Time (sec)

Rectified Known Dynamometer


Experimental Set-up

Top view for ConventionalDrilling of Ti6Al4V

Exit

EntranceTi plate

Tool

Feed direction

Temperature measurement

Top view forVAD of Ti6Al4V

Exit

EntranceTi plate

Tool

Feed direction

Temperature measurement

Modulation

IR Camera

Tool

Conventional; Tmax = 813 ˚C VAD; Tmax = 469 ˚C

Material: TiAl6V4Rotating speed =2,500 rpmFeed fr=0.06 mm/revAmplitude (p-to-p)= 400 mm Frequency= 30 HzTool: 2-Flute 6 mm WC drill bitLubrication mode: Dry


Full factorial VAD experiments (3N x 3fr x 3 freq x 3 axial speed ratio ASR).

At least 2 replicates for each condition.

Each VAD case has been compared to a corresponding reference conventional drilling.

Test MatrixVAD Conditions

Workpiece Material: Cross-ply laminate, 42 plies of graphite epoxy prepregs. Final cured thickness of 8.0 ± 0.02 mm.

Tool: Two flute 6.0 mm WC drill with a total length of 63 mm. No pilot holes.A new tool was used after 9 holes.

ASR = Aω / (2n fr) , ASR >1

Feed (mm/rev) 0.025 (mm/rev) 0.05 (mm/rev) 0.075 (mm/rev)

Freq. (Hz) 30 45 60 30 45 60 30 45 60RPM ASR Amplitude Peak-to-Peak (μm)

60003.3 45 30 25 90 60 45 135 90 706.7 90 60 45 180 120 90 270 180 13510 135 90 70 270 180 135 400 270 200

90003.3 70 45 35 135 90 70 200 135 1006.7 135 90 70 270 180 135 400 270 20010 200 135 100 400 270 200 600 400 300

120003.3 90 60 45 180 120 90 270 180 1356.7 180 120 90 360 240 180 535 360 27010 270 180 135 535 360 270 800 535 400


Is the dimensionless variable ASR an intrinsic property that uniquely captures the combined effect of different process variables?Tests were conducted for the same value of ASR, but at different combinations of A, ω, f r , and n.

Test Matrix

Workpiece Material: Cross-ply laminate, 42 plies of graphite epoxy prepregs. Final cured thickness of 8.0 ± 0.02 mm.

Tool: Two flute 6.0 mm WC drill with a total length of 63 mm. No pilot holes.A new tool was used after 9 holes.

ASR =Aω / (2n fr), ASR > 1

Feed (mm/rev) 0.025 (mm/rev) 0.05 (mm/rev) 0.075 (mm/rev)

Freq. (Hz) 30 45 60 30 45 60 30 45 60RPM ASR Amplitude Peak-to-Peak (μm)

60003.3 45 30 25 90 60 45 135 90 706.7 90 60 45 180 120 90 270 180 13510 135 90 70 270 180 135 400 270 200

90003.3 70 45 35 135 90 70 200 135 1006.7 135 90 70 270 180 135 400 270 20010 200 135 100 400 270 200 600 400 300

120003.3 90 60 45 180 120 90 270 180 1356.7 180 120 90 360 240 180 535 360 27010 270 180 135 535 360 270 800 535 400

VAD Conditions


Axial forces “FA”: Feed has the most significant

effect on FA (+): Feed chip thickness and FA.

Rotational speed ‘n’ has the least effect on FA (-).

ASR causes FA

Different force levels obtained for the same ASR value; ASR is notan intrinsic property that can uniquely control the VAD forces.

Results: Drilling Forces

0

50

100

150

200

250

0.02

5

0.05

0.07

5

0.02

5

0.05

0.07

5

0.02

5

0.05

0.07

5

6000 9000 12000

Axia

l For

ce (N

)

ASR=3.3

ASR=6.7

ASR=10.0

0 0.5 1.0 1.5 2.0 2.5

200

160

120

80

40

0

Forc

e (N

)

Time (s)

Frequency = 30 Hz

Feed:

n (rpm):

n =12,000

f = 0.075

ASR = 10

��

f ( DoC) = f { wm / wT}


Axial forces “FA”:

For a given ASR, moving horizontally: (amplitude + frequency ): DOC ,engagement time , FA.

Increasing ASR, moving down: (amplitude + same frequency and engagement time): DOC, FA

Compared to conventional drilling, FA (45% at min. ASR; gradual cutting; smaller A). FA (60% at max. ASR; higher A + maximum engagement).

0.025 mm/rev 0.05 mm/rev 0.075 mm/revFrequency (Hz)

30 60 30 60 30 603.3 -10.0 -19.7 -0.2 -11.7 -0.4 -10.66.7 0.8 -22.0 22.4 -10.7 21.5 -10.710.0 12.6 -18.5 39.0 -6.8 47.6 -2.13.3 0.2 -4.5 8.4 -1.7 9.6 -5.76.7 29.2 2.3 19.6 5.0 30.4 8.710.0 17.7 -8.6 28.9 -3.6 32.7 5.13.3 -37.7 -43.1 -11.7 -17.2 -6.4 -13.56.7 4.9 -27.9 11.5 -1.0 16.5 8.310.0 42.1 14.4 59.7 20.1 27.7 34.8

6000

9000

12000

Feed

rpm ASR

30 60 30 60 30 603.3 76.0 67.7 106.5 94.2 135.9 122.06.7 85.0 65.8 130.5 95.2 165.7 121.910.0 95.0 68.8 148.2 99.4 201.3 133.53.3 75.6 72.1 115.7 104.9 148.9 128.16.7 97.5 74.0 127.7 112.1 177.1 147.610.0 88.9 69.0 137.6 102.9 180.3 142.83.3 46.4 42.4 98.0 92.0 131.7 121.76.7 78.2 53.7 123.7 109.9 163.9 152.210.0 105.9 85.2 177.3 133.4 179.6 189.6

6000

9000

12000

Feed 0.025 mm/rev 0.05 mm/rev 0.075 mm/rev

rpm ASR Frequency (Hz)

< - 20%

>20%

>20%>20%

±10%

±10%±10%

±10%

125-200 N

75-125 N

75 –125 N

<75 N>125 N

150- 200 N

75 –125 N

125-200 N

125-200 N

125-200 N

125-200 N

<75 N<75 N

<75 N

Comparative axial force (VAD vs Conventional)

Absolute maximum axial force

Results: Drilling Forces

ASR = Aω / (2n f)

�� 2��

6000 6.7 90 45 180 90 270 135

60003.3 45 25 90 45 135 706.7 90 45 180 90 270 13510.0 135 70 270 135 400 200


Comparative max Temp. (VAD vs Conventional)

Results: Cutting Temperatures

o Generally, feed tool temperature (temperature build up )

Feed

30 60 30 60 30 603.3 -2.4 1.1 -3.9 -13.4 -5.9 -21.76.7 0.1 4.1 0.9 -0.4 3.0 -5.210.0 -0.6 3.5 2.2 3.2 6.7 6.03.3 5.2 -0.3 8.5 11.0 10.0 18.86.7 13.1 14.6 18.1 9.3 7.6 1.710.0 4.9 5.9 9.8 13.4 2.3 -0.43.3 -49.4 -47.1 0.4 0.4 -8.0 -6.16.7 -20.5 -39.7 2.6 3.9 -10.0 0.510.0 2.8 -2.5 6.0 7.3 -15.5 -0.8

rpm0.025 mm/rev 0.05 mm/rev 0.075 mm/rev

ASR Frequency (Hz)

6000

9000

12000 < -20%

5-20%

± 5%

± 5%

± 5%-20% to -5%

- 20% to - 5% <-20%

±5%

>20%

Feed

30 60 30 60 30 603.3 313.8 328.9 293.2 270.1 262.8 213.56.7 311.9 323.4 299.4 285.2 273.8 248.210.0 306.3 322.6 293.6 291.0 259.5 270.83.3 333.6 329.2 308.6 312.8 276.0 300.06.7 362.1 377.3 331.2 310.6 282.9 286.210.0 308.3 342.9 300.1 306.0 266.5 257.93.3 171.8 184.8 290.3 292.6 268.7 265.96.7 289.1 183.9 292.2 299.0 260.0 277.510.0 329.8 356.3 299.5 307.9 252.5 275.5

rpm0.025 mm/rev 0.05 mm/rev 0.075 mm/rev

ASR Frequency (Hz)

6000

9000

12000<200 °C

320 -360°C

280 -320°C

280 - 320°C

240 - 280°C

240 -280°C

200 -240°C

320 -360°C

Absolute maximum temperature

ASR = Aω / (2n fr)

o Best Condition (T<200°C): Low feed, high speed and low ASR:

Q generation : lower A.Q dissipation : high n and lower air gap (optimum range): high hg.

o Worse condition T=360°C: Low feed, high speed and high ASR:

Q generation : n, A are high, feed is low allowing heat accumulation. Q dissipation : higher A and air gap that produces lower hg.

o Complexity of the HT process: Competition between Qin and Qout ; n

(Ec vs hg), fr (Ec vs tconductn), Non-monotonic effect; A (or g), wm/wT.


Results: Delamination and thermal damage In all conventional drilling tests: Exit delamination + certain

degree of thermal damage observed. In all VAD tests: No noticeable thermal damage

Although 360oC was reached on the tool (not the wp); DT reduction during interrupted cutting > 100K. Upon re-engagement, Tc is further reduced < 280oC.

In VAD at low feeds: Delamination totally eliminated. Increase in delamination in the range of high feed, and low/

medium speeds.

Conventional Drilling Rotational speed 6,000 rpm

and f= 0.025 mm/rev

Matrix burnout

Uncut fibers

Feed

30 60 30 60 30 603.3 -0.1 -0.1 0.2 0.3 0.4 0.36.7 -0.1 -0.1 -0.1 0.1 0.3 0.3

10.0 -0.1 -0.1 0.1 0.1 0.1 0.33.3 -0.1 -0.1 0.1 -0.1 0.3 0.36.7 -0.1 -0.1 0.0 0.1 0.3 0.4

10.0 -0.1 -0.1 0.2 0.1 0.3 0.43.3 -0.1 -0.1 0.2 -0.1 0.1 0.06.7 -0.1 -0.1 -0.1 0.1 -0.1 0.2

10.0 -0.1 -0.1 0.0 0.2 0.1 0.2

0.025 mm/rev 0.05 mm/rev

9000

12000

rpm0.075 mm/rev

ASR Frequency (Hz)

6000

Delamination-free

Up to 20%

20% to 40%

Up to 20%

Up to 20%

Comparative exit delamination factor f VAD vs Conventional:

Dd

Dn

(f = (Dd - Dn)/ Dn


30 45 60 30 45 60 30 45 60 30 45 60 30 45 60 30 45 60

3.3 0.0 0.0 0.0 0.3 0.3 0.4 0.6 0.5 0.5 1.5 1.5 1.7 1.6 2.1 1.4 1.5 1.7 1.66.7 0.0 0.0 0.0 0.0 0.2 0.3 0.5 0.6 0.6 2.2 2.4 2.4 1.7 1.9 1.6 1.7 2.1 1.910.0 0.0 0.0 0.0 0.3 0.3 0.3 0.3 0.6 0.5 2.4 2.7 2.7 2.2 2.1 1.9 3.3 3.0 3.63.3 0.0 0.0 0.0 0.2 0.0 0.0 0.5 0.6 0.5 2.7 2.6 2.4 2.2 2.2 1.9 2.2 2.4 2.46.7 0.0 0.0 0.0 0.1 0.3 0.3 0.5 0.6 0.5 4.0 4.0 4.1 2.9 2.8 3.0 2.0 2.0 2.110.0 0.0 0.0 0.0 0.4 0.1 0.2 0.4 0.6 0.6 4.8 5.0 5.0 4.3 4.4 4.8 2.0 2.1 2.13.3 0.0 0.0 0.0 0.3 0.3 0.2 3.9 3.5 2.8 3.3 3.2 3.56.7 0.0 0.0 0.0 0.0 0.0 0.6 3.6 3.9 2.4 3.1 3.1 3.010.0 0.0 0.0 0.0 0.2 0.0 0.4 0.4 0.6 0.5 6.3 5.9 6.2 4.4 4.7 4.5 4.6 4.0 4.1

3.3 ### ### ### ### ### ### ### ### ### 0.0 0.0 0.0 -0.1 -0.1 -0.1 -0.1 -0.1 -0.16.7 ### ### ### ### ### ### ### ### ### 0.0 0.0 0.0 -0.1 -0.1 -0.1 -0.1 -0.2 -0.210.0 ### ### ### ### ### ### ### ### ### 0.0 0.0 0.0 0.0 -0.1 -0.1 -0.1 -0.2 -0.13.3 ### ### ### ### ### ### ### ### ### 0.0 0.0 0.0 -0.1 -0.1 -0.1 -0.2 -0.2 -0.26.7 ### ### ### ### ### ### ### ### ### 0.0 0.0 -0.1 -0.1 -0.1 -0.1 -0.1 -0.1 -0.110.0 ### ### ### ### ### ### ### ### ### 0.1 0.0 0.0 -0.1 0.0 0.0 -0.1 -0.1 -0.13.3 ### ### ### ### ### ### 6.3 6.2 6.4 0.3 0.3 0.36.7 ### ### ### ### ### ### 2.7 1.4 5.8 0.3 0.4 0.410.0 ### ### ### ### ### ### ### ### ### 0.6 0.4 2.9 0.2 0.6 0.6 0.3 0.5 0.5

Allowable range (a) Exit delamination<0.5, (b) Ra<3µm, (c) Circularity <0.02 mm and (d) -0.7%<Hole size error<0.4%Out of Tolerance range

9000

12000

6000

9000

12000

(c) Hole Circularity (mm) (a) Hole size error %

6000

0.075 mm/rev

rpm ASR Frequency (Hz) Frequency (Hz)

(a) Exit delamination factor (b) Surface roughness (Ra)

Feed 0.025 mm/rev 0.05 mm/rev 0.075 mm/rev 0.025 mm/rev 0.05 mm/rev

Optimum operating range

Objectives: Max. Productivity

(Max. ‘n‘ and ‘fr‘) Allowable hole

quality

Optimum conditions fr=0.05 mm/rev, n=12,000 rpm, m=30, 45, 60 Hz, ASR = 3.3, 6.7

Results: Hole Quality Optimization

Exit Delamination Factor Surface Rougness Ra (mm)

Hole Circularity Error Hole Size Error %


VAD Parameters(n,fr,�m,Am)

Tool geometry

Material layup configuration

Inputs

VAD Force Prediction Model

ii�1n


Process kinematics formulation


Tool geometry


Inputs


-0.4

-0.2

0

0.2

0 5 10

Position(mm)


D2 D1 DOC




Tool geometry


Inputs

Formed chip dynamic geometry

Cutting edge sections


ni

I +1

Tool-workpiece interaction

12 3

Relative tool –workpieceposition qe

eee


0.050.1

0.150.2

0100

200300

0

200

400

600

Cut

ting

Pres

sure

(N/m

m2 )

feed (mm/rev)qe (deg)

Output:Predicted forces

and torques


Hybrid mechanistic model formulation


Tool geometry


Inputs

Formed chip dynamic geometry

Cutting edge sections

Tool-workpiece interaction Experimentally

defined Material Properties


0.050.1

0.150.2

0100

200300

0

200

400

600

Cut

ting

Pres

sure

(N/m

m2 )

feed (mm/rev)qe (deg)

Axial cutting pressures of (a) the primary and (b) chisel cutting edges for all frand qe at N= 6000 rpm.

(a) (b)

Relative tool –workpieceposition qe


00,10,20,30,40,50,6

1,50

1,52

1,55

1,58

1,61

1,64

1,66

1,69

1,72

1,75

1,78

1,80

Torq

ue (N

.m)

Time (s)

Measured Predicted

0,020,040,060,080,0

100,0120,0

1,50

1,52

1,55

1,58

1,61

1,64

1,66

1,69

1,72

1,75

1,78

1,80

Axia

l For

ce (N

)

Time (s)

Measured Predicted

Model Validation

fr=0.05 mm/rev, n=12,000 rpm,�m=30 Hz, Am= 0.09 mm

-25

-15

-5

5

15

25

30 60 30 60

0.090 0.135

Max

imum

forc

e er

ror %

Frequency (Hz)Amplitude (mm)

Steady State Entrance Exit

-25

-15

-5

5

15

25

30 60 30 60

0.090 0.135

Max

imum

torq

ue e

rror

%

Frequency (Hz)Amplitude (mm)


1. The force reduction in the Intermittent cutting in VAD is achieved through the progressive removal of the formed chip, provided that A is moderate w.r.t. DOC.

2. The thermal performance of the VAD process is enhanced by the formation of vortices in the air gap created by the tool separation.

3. The axial speed ratio ASR is not intrinsic property and cannot uniquely define the cutting temperature and force in VAD.

4. The VAD process can eliminate exit delamination and thermal damage (al low/ medium feeds).

5. Generally, the optimum range of LFHA-VAD is defined by the combination of high speed with low-to-medium feed, low ASR and high frequency.

6. A novel semi analytical model was developed to accurately predict the transient features of the forces in conventional and VAD, considering the effects of: Process variables. Material layup configurations (on the chip formation mechanism). Material deformation during drilling. Tool geometry ad rake angle variation along the primary cutting edge.

Concluding Remarks

Advanced Material Removal Program

Vielen Dank für Ihere Aufmerksamkeit!

A. Sadek 2 1 and Helmi Attia 1,2 - P · PDF fileA. Sadek 2, M. Meshreki 1 and Helmi Attia 1,2...

Documents

Transcript of A. Sadek 2 1 and Helmi Attia 1,2 - P · PDF fileA. Sadek 2, M. Meshreki 1 and Helmi Attia 1,2...