05 computer numerical control - Teknik Industri UMS

05
COMPUTER NUMERICAL
CONTROL
Dosen : Much Djunaidi
Presentasi Kuliah
TKI-313 Sistem Produksi
Jurusan Teknik Universitas Muhammadiyah Surakarta
Types of Automation
Manufacturing
Automation
Hard/ Rigid/ Mechanized
Automation
Copy milling machines
Automats
Special purpose machines
Soft/ Flexible/ Programmable
Automation
CNC Machines
Robots
Automatically Guided Vehicles (AGVs)
Reconfigurable conveyors
Unlimited muscle power
Speed
Advantages of Soft
Accuracy
Automation
Unmanned operation
Flexibility
Simplified generic tooling even for the most complex jobs
CNC - Pengantar
Secara konvensional, operator menentukan dan mengatur
berbagai parameter mesin, seperti kecepatan pemakanan
(feed), kedalaman (depth of cut), dsb, tergantung jenis
pekerjaannya, dan mengendalikan pergerakan dengan
tangan.
Pada CNC Machine, fungsi dan pergerakan dikendalikan
dengan motor menggunakan computer programs.
Fungsi dasar dari CNC machine adalah pengendalian
gerakan secara automatic, precise, dan consistent.
Dua jenis sumbu yang biasa digunakan adalah linear
(driven along a straight path) dan rotary (driven along a
circular path).
Why CNC is Accurate?
Light but rigid
construction
Hollow design with ribs to have less deflection and low
nat. freq., Design improvement using mode shape
analysis
Low inertia
Keep weight of moving elements low
Low friction and play
Guide way elements, Ball lead screws, Pre-loading
Good damping
Appropriate material selection
Minimization of thermal
effects
Control of ambient temperature (humidity and
suspended dust too), Use of thermally stable material,
Thermal compensation
Advanced electrical and Advanced drives, Accurate sensors for position,
electronics and
velocity, force, vibration, temp. etc., Sophisticated
computing
feedback control loops, Interpolators
Error compensations
Axis calibration & pitch error compensation, Diameter
and length compensations, Adaptive control
Accurate manufacture
Use of accurate manufacturing processes
Defining Axes
Primary
Secondary
Tertiary
X
U
P
Y
V
Q
Z
W
R
Spindle is Z axis
Moving away is ‚+‘
Imagine table stationary
Take longest as X axis
Defining Axes
Lathe
Vertical Machining Center
Important G Codes
G00 Rapid Transverse
G01 Linear Interpolation
G02 Circular Interpolation, CW
G03 Circular Interpolation, CCW
G17 XY Plane,G18 XZ Plane,G19 YZ Plane
G20/G70 Inch units
G21/G71 Metric Units
G40 Cutter compensation cancel
G41 Cutter compensation left
G42 Cutter compensation right
G43 Tool length compensation (plus)
G43 Tool length compensation (plus)
G44 Tool length compensation (minus)
G49 Tool length compensation cancel
G80 Cancel canned cycles
G81 Drilling cycle
G82 Counter boring cycle
G83 Deep hole drilling cycle
G90 Absolute positioning
G91 Incremental positioning
Important M Codes
M00 Program stop
M01 Optional program stop
M02 Program end
M03 Spindle on clockwise
M04 Spindle on counterclockwise
M05 Spindle stop
M06 Tool change
M08 Coolant on
M09 Coolant off
M10 Clamps on
M11 Clamps off
M30 Program stop, reset to start
Modal and Non-Modal Commands
Modal commands: Commands issued in the NC
program that will stay in effect until it is changed by
some other command, like, feed rate selection, coolant
selection, etc.
Non-modal commands: Commands that are effective
only when issued and whose effects are lost for
subsequent commands, like, a dwell command which
instructs the tool to remain in a given configuration for a
given amount of time.
Open Loop and Closed Loop System
Tape Preparation
Punch holes in channels 6
and 7 pulse numeric value
Punch holes in channels 7
pulse numeric value
Punch holes in channels 6
pulse numeric value
1= a
2= b
3=c
4=d
5=e
6=f
7=g
8=h
9=i
1= j
2= k
3=l
4=m
5=n
6=o
7=p
8=q
9=r
2= s
3=t
4=u
5=v
6=w
7=x
8=y
9=z
Programming : Absolute and Incremental
5 – Parity check
6 – Zero
7- Minus
8 – End of info
EIA
ASCII
Features of a CNC Systems
The tool or material moves.
Tools can operate in 1-5 axes.
Larger machines have a machine control unit (MCU)
which manages operations.
Movement is controlled by a motors (actuators).
Feedback is provided by sensors (transducers)
Tool magazines are used to change tools
automatically.
Types of Interpolations
Point to Point - No contouring capability
Straight cut control - one axis motion at a time is
controlled for machining
Contouring - multiple axis’s controlled simultaneously
Sample Programming
Preparatory Information: units, incremental or absolute positioning
Coordinates: X,Y,Z, RX,RY,RZ
Machining Parameters: Feed rate and spindle speed
Coolant Control: On/Off, Flood, Mist
Tool Control: Tool and tool parameters
Cycle Functions: Type of action required
Miscellaneous Control: Spindle on/off, direction of rotation, stops for
part movement
This information is conveyed to the machine through a set of
instructions arranged in a desired sequence – Program
Sample Programming
Manual Part Programming: Manual programming of the
machines
Computer Aided Programming (CAP): Programming
done by a computer
Manual Data Input (MDI): A manual program is entered
into the machine’s controller via its own keyboard
Sample Programming
5”
2.5”
p3
p2
p4
p5
1”
Tool size = 0.25 inch,
Feed rate = 6 inch per minute,
Cutting speed = 300 rpm,
Tool start position: 2.0, 2.0
Programming in inches
5”
45°
(4, 4)
p1
p0 (2, 2)
Motion of tool:
p0  p1  p2  p3  p4  p5  p1  p0
Sample Programming
5”
2.5”
p3
p2
p4
p5
Set up the programming
parameters
1”
Programming in inches
5”
Use absolute coordinates
Feed in ipm
45°
N010 G70 G90 G94 G97 M04
(4, 4)
p1
p0 (2, 2)
Spindle speed in rpm
Spindle CCW
Sample Programming
5”
2.5”
p3
p2
p4
p5
Set up the machining
conditions
1”
Machine moves in XY-plane
Use full-circle interpolation
5”
Feed rate
Spindle speed
45°
N020 G17 G75 F6.0 S300 T1001 M08
(4, 4)
p1
p0 (2, 2)
Tool no.
Flood coolant ON
Sample Programming
Move tool from p0 to
p1 in straight line
5”
2.5”
p3
p2
1”
p4
p5
Linear interpolation
target coordinates
N030 G01 X3.875 Y3.698
5”
45°
(4, 4)
p1
p0 (2, 2)
Sample Programming
Cut profile from p1 to p2
5”
2.5”
p3
p2
p4
p5
1”
Linear interpolation
5”
target coordinates
N040 G01 X3.875 Y9.125
45°
or
(4, 4)
p1
N040 G01 Y9.125
p0 (2, 2)
X-coordinate does not change  no need to program it
Sample Programming
Cut profile from p2 to p3
5”
2.5”
p3
p2
p4
p5
Linear interpolation
target coordinates
1”
N050 G01 X5.634 Y9.125
5”
y = 9 + 0.125 = 9.125
(6.5 - x)2 + 0.1252 = (1 - 0.125)2
x = 5.634
45°
p3
(x, y)
(4, 4)
p1
(6.5, 9)
.125
p0 (2, 2)
1”
Sample Programming
5”
2.5”
p3
p2
p4
Cut along circle from p3 to
p4
p5
1”
circular interpolation, CCW motion
5”
target coordinates
45°
(4, 4)
p1
p0 (2, 2)
N060 G03 X7.366 Y9.125 I0.866 J-0.125
coordinates of center of circle
(always in incremental )
Sample Programming
Complete Programming
N010 G70 G90 G94 G97 M04
N020 G17 G75 F6.0 S300 T1001 M08
N030 G01 X3.875 Y3.698
N040 G01 X3.875 Y9.125
N050 G01 X5.634 Y9.125
N060 G03 X7.366 Y9.125 I0.866 J-0.125
N070 G01 X9.302
N080 G01 X3.875 Y3.698
N090 G01 X2.0 Y2.0 M30
Adaptive Control
1. Adaptive control with constraints
2. Adaptive control with optimization
Advantage of NC
Increased productivity
Reduced tool/fixture storage and cost
Faster setup time
Reduced parts inventory
Flexibility that speeds changes in design
Better accuracy of parts
Reduction in parts handling
Better uniformity of parts
Better quality control
Improvement in manufacturing control
Disadvantages
Increase in electrical maintenance
High initial investment
Higher per-hour operating cost than traditional machine
tools
Retraining of existing personnel
NC is a general term used for Numerical Control. CNC
refers specifically to COMPUTER NUMERICAL CONTROL.
CNC machines are all NC machines but not all NC
machines are CNC machine.
Applications
• Traditional machining
– Turning, boring, milling, grinding etc.
• Sheet metal manufacture
– Turret punch press, pipe bending, flow forming etc.
• Non-traditional machining
– Wire-EDM, water-jet cutting, electron beam machining, laser
beam machining, plasma cutting etc.
•
•
•
•
Coordinate Measuring Machines
Drafting machines
Robots
Rapid Prototyping (RP) machines
NC is a control technique; not a process
END