Laser Assisted Machining P. Mitchell, Prof. G. Byrne and R. Byrne Email: [email protected]
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University College Dubli n Mechanical Engineering Laser Assisted Machining P. Mitchell, Prof. G. Byrne and R. Byrne Email: [email protected] Abstract Laser Assisted Machining (LAM) allows difficult-to-cut materials to be machined by conventional cutting tools with greater ease. During LAM, a laser beam tracks ahead of the cutting tool selectively heating the workpiece material, reducing its shear strength in a localised region. The heated material is then removed in chip form by the tool. The most suitable LAM workpiece materials are hardened steels, titanium and nickel based alloys and ceramics. Benefits of the process include reduced cutting forces, increased material removal rates, machining without lubrication and the use of more economic cutting tools. Recent increases in the power capability of High-Power Diode Lasers (HPDL) have made them suitable for materials processing. The HPDL is compact, cost effective and efficient when compared to the traditional materials processing lasers (CO 2 and Nd:YAG). It also has a unique Top-Hat by Gaussian beam profile. An analytical 3D thermal model of the laser heating process has been developed. This model shows the temperature profile generated in the workpiece due to the laser beam. A 3kW HPDL has been integrated into an ultra precision CNC turning centre. The laser is mounted on a unique positioning system that allows the optimum LAM process parameters (laser-tool lead distance, laser power, beam profile orientation and dimensions and machining parameters) to be established. LAM experiments are being conducted on hardened steel (AISI 4340 at 53HRC) at a range of laser powers. Initial results show significant cutting force reduction for LAM compared to conventional machining of hardened steel (AISI4340 at 53 HRC). Laser Beam Tool Chip Heated Area Primary Shear Zone Vc Principle Thermal Model High Power Diode Laser Initial Results Cutting force reduction for LAM compared to conventional machining (CM) of Hardened Steel (AISI4340 at 53 HRC) Experimental Set Up HPDL Unit (Courtesy of Laserline) Top-hat Distribution Gaussian Distributi on HPDL Beam Profile (Courtesy of Laserline) dr e z r r y r x I T z y x T z r r U r a 2 2 0 2 0 2 2 ) , ( U 1 ) , , ( T(x,y,z) = Temperature at position (x,y,z) (K) T 0 = Initial Workpiece Temperature (K) = Thermal Conductivity (W/mK) = Thermal Diffusivity (W/m 2 ) U = Constant Velocity of Translation in X Direction (m/s) Machining Parameters: f = 0.15mm, a p = 0.2mm v c = 150 m/min Force (N) -100 0 100 200 300 400 500 10:50 10:50 10:51 10:52 10:53 10:53 10:54 Time (min) CM LAM Lase r Dynamometer Cuttin g Tool Workpiece Chuck
description
CM. LAM. Force (N). Time (min). Laser Assisted Machining P. Mitchell, Prof. G. Byrne and R. Byrne Email: [email protected] Abstract - PowerPoint PPT Presentation
Transcript of Laser Assisted Machining P. Mitchell, Prof. G. Byrne and R. Byrne Email: [email protected]
University College Dublin Mechanical Engineering
Laser Assisted MachiningP. Mitchell, Prof. G. Byrne and R. Byrne
Email: [email protected]
AbstractLaser Assisted Machining (LAM) allows difficult-to-cut materials to be machined by conventional cutting tools with greater ease. During LAM, a laser beam tracks ahead of the cutting tool selectively heating the workpiece material, reducing its shear strength in a localised region. The heated material is then removed in chip form by the tool. The most suitable LAM workpiece materials are hardened steels, titanium and nickel based alloys and ceramics. Benefits of the process include reduced cutting forces, increased material removal rates, machining without lubrication and the use of more economic cutting tools. Recent increases in the power capability of High-Power Diode Lasers (HPDL) have made them suitable for materials processing. The HPDL is compact, cost effective and efficient when compared to the traditional materials processing lasers (CO2 and Nd:YAG). It also has a unique Top-Hat by Gaussian beam profile. An analytical 3D thermal model of the laser heating process has been developed. This model shows the temperature profile generated in the workpiece due to the laser beam. A 3kW HPDL has been integrated into an ultra precision CNC turning centre. The laser is mounted on a unique positioning system that allows the optimum LAM process parameters (laser-tool lead distance, laser power, beam profile orientation and dimensions and machining parameters) to be established. LAM experiments are being conducted on hardened steel (AISI 4340 at 53HRC) at a range of laser powers. Initial results show significant cutting force reduction for LAM compared to conventional machining of hardened steel (AISI4340 at 53 HRC).
Laser Beam
ToolChip
Heated Area
Primary Shear Zone
Vc
Principle
Thermal Model
High Power Diode LaserInitial ResultsCutting force reduction for LAM compared to conventional machining (CM) of Hardened Steel (AISI4340 at 53 HRC)
Experimental Set Up
HPDL Unit (Courtesy of Laserline)
Top-hat Distribution
Gaussian Distribution
HPDL Beam Profile (Courtesy of Laserline)
drezr
ryrxITzyxT
zrrU
r a
22
02
0 22),(
U
1),,(
T(x,y,z) = Temperature at position (x,y,z) (K)
T0= Initial Workpiece Temperature (K)
= Thermal Conductivity (W/mK)
= Thermal Diffusivity (W/m2)
U = Constant Velocity of Translation in X Direction (m/s)
Machining Parameters: f = 0.15mm, ap= 0.2mm vc= 150 m/min
Forc
e (
N)
-100
0
100
200
300
400
500
10:50 10:50 10:51 10:52 10:53 10:53 10:54
Time (min)
CM
LAM
Laser
Dynamometer
Cutting Tool
Workpiece
Chuck
