Automation of machine tools programming
Ing. Jan Tomíček
Course description
Course is focused fundamental possibilities of automatization of machine tools and automatization of programme preparation for CNC machine tools.
1+2, CA – classified assessment - 3 credits
Presentations Exercises
› common tasks› individual work
Presentations
1+2, 1 hour of presentation, 2 of exercise => 13 + 13 weeks (13+26) => 4 + 9 approx.
(12+27)presentation explain the work on exercise =>
presentation will be together on the beginning
and then you will have time to make the task and individual work!
Lesson 1 – Automation overview
longer presentationno exercise or task
Introduction
Work on conventional machines is replaced by automated work on automatic machines. These machines are working without human control with higher speed, precision, safer and more productivly than humans.
But where did it start?
Automation of machining
Is connected with the rising demands of society and industry development.
Is the way to intensification of manufacturing – increasing productivity, improving quality and lowering costs
Is the way to improvements in manufacturing technology, spreading the technological possibilities and way to make the inovation cycle faster.
What we need to automate?
Tool management Tool change Tool movements Spindle start, devices start Material loading Finished piece remove
AUTOMATION OF MACHINING
Machine tools: general-purpose, manually operated
(conventional);
- The leading power is the worker
AUTOMATION OF MACHINING
Machine tools: automated:
a) fixed automation – mechanisms: cams,gear wheels, links, levers, arms; mechanical stops, limit switches, etc.b) flexible automation – program control, numerical control
Fixed automation elements
Cam
Is a disc or cylinder with a curve shaped path. A boss in support is in the path and as the cam turns the support moves. Cam are connected together to provide complex movement of support, feed, rotation and other.
Cylindrical cam use – automatic lathe carriage
Fixed automation machine tools
automatic general-purpose machinee.g. a semiautomatic or an automatic lathe
single-purpose machine (usually unit-built)workpiece oriented function design
transfer lineintegrated workpiece transport system
Unit-built machine
Modular units design
Single purpose machine
Just one operation, of op. Step is done. Sometimes a batch of operation steps Special machine designed to maximize
the production:› Multiple spindles› High feed drives› Multiple clamping› Automatic part in feed› Special tooling usage
Single-purpose machine efficiency
Transfer line – a concept
Transfer line – a schema
Block machining transfer line
Video – Transfer line
Transfer line station – an example
2) Flexible automation
(soft, programable automation) is aimed at piece and small batch production due to easy reprogramming.
Two basic forms Program sequence control Numerical control
Program sequence control
The sequence of motions and switchings is controlled by relays, timers, switches, perforated tape, programable cylinders, plugboards and other controllers.
Easier reprogramming, limited program options, almost no adjustments
Perforated tapeEach line presents a different movement or switch. It has to be printed correctly, no error control.
FYI:8 line perforated paper tape can contain one byte of information in one column of holes. Normal pitch of columns is 2,54 mm. That means you need 2,6 m of tape to store 1kB of data. A dual-layer DVD is then approx. 22100 km of perforated tape.
Numerical control
The most important type of automation. Almost all of new machines are numerically controlled.
Priciple:Machine and all of its movements are controlled by a program. Program is a list of instructions written is specific syntax and having specific format.
Mechanical vs. numerical
Limitations – speed, length of program, possible motions on cams.
FLEXIBLE AUTOMATION1. Conventional machine tool
FLEXIBLE AUTOMATION2. NC machine tool (stand-alone)
FLEXIBLE AUTOMATION3. NC machine tool with tool magazine
FLEXIBLE AUTOMATION4. CNC machine tool
Mechanization vs. automation
Mechanization – human power is replaced by machines, drives, hydraulic or mechanic devices
Automation – human control is replaced by sequentional machine, cams, computer, PLC controller
Automation degree
Semiautomatic run – tools are changed automatically, blank or finished workpiece is renowed by operator
Automatic run – both the tool and pieces are placed and removed automatically by robot (line, tables)
What we need to automate?
Tool management Tool change Tool movements Spindle start, devices start Material loading Finished piece remove
Sem
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NC / CNC definition
Originaly only NC control was used. Program was stored on tape or disc and read one line after another. Influence of rapid development of computers resulted to CNC control (Computer numerical control). Now the program is loaded into computers memory and executed from here.
CNC advantagesOption NC control CNC control
Program length Limited by data storage capacity (tape)
Unlimited (limited by data storage capacity – HDD drives over 1TB)
Program sequence One line after another Allows jump forward, backward, subprograms.
Jump to other programs N/A Yes
Canned cycles N/A Yes
Coordinates correction Manually only Yes, automatically
Tool length compensation Manually only Yes, programable
Tool diameter compensation
N/A Yes, programable
Reading in advance N/A Yes, continual mode
Start after breakdown N/A Yes
Basic principles of CNC machines
NC/CNC machine consist of 3 basic elements.List of instructions – NC code – a mix of alphabecial and
numerical information. Contaion information about movements, feed, speed, tool change and other machine functions (cooling, measuring)
Control unit - control system – converts the program into signal for machine and send them to machine (PLC controller)
Control unit
(system)
MachineNC
code
Sensing device
Drive motor
Basic principles of CNC machines
NC/CNC machine consist of 3 basic elements.Machine tool – fitted with drive motor to operate
slides, support and spindle. Also with switches to start/stop specific functions
Sensing device – optional(closed circuit)- sensing device control if a specific demand was fullfilled. Support feed, Table position etc.
Control unit
(system)
MachineNC
code
Sensing device
Drive motor
CNC machine tool
Motions
Three types of motion1) point-to-point motion – tool is moved to
specific location, path or speed of move between location is not controlled. (drilling)
2) Linear control – movement along one of the axes of the machine.
3) Contouring control – movement can be made in two or more axes simultaneously.
MotionsPoint-to-point control Linear control Contouring control (continual)
drilling milling machines, lathes machining c.(milling, turning)
CNC machining centre(MC)
MC combine a number of different machining processes in one operation
Modular tool set
Modular tool set – tooling system
All manufacturers around the worldBasic concept:1) Holder with standadized conecting
part – ISO, BSK cone, CAPTO system etc.
2) Extension bar – active (vibration elimination) adujstable and balanced
3) Quick change tooltip/insert
SECO - Combimaster
Tool exchange
Tool exchange
Flexible cell – a concept
Flexible manufacturing system
Conveyors
Device used for transportation of blank and semiproduct in production
Types:Belt conveyorPulley(rolls) conveyorCradle conveyor
Conveyors – Belt conveyor
Used for small parts and loose material Endless belt made of rubber, plastic
particles, short boards (grids)
Conveyors – pulley(roller) conveyor
For large solid parts and products Low force needed (gravity slide ways) Use of pallets
Video – conveyor
PalletBoard used for
transportationEquiped with jigs and
other positioning elements
Together with pallete changer is used for automatic blank material loading and parts unloading
Pallet changeraka Switch table2-4 pallets in one machine
Loading of blank/semiproducts
- Manual- Accumulation conveyor
- Accumulating pieces to balance production- Robot loading
- For single standing, large production usage (common machine tools)
- Line(conveyor) loading- For FMS and large batch production
(special machine tools)
Loading
Flexible manufacturing system
Flexible manufacturing system for 4 types of automobile cylinder heads
(GM 3801 – 3811)
BZ 400 BZ 500 Other Reserve
Flexible to suit various part variants
9 Flexible transfer machines (some incorporating BZ 400 machining centers),
and 16 high-dynamic BZ 500 machining centers
Completely automated
Approximately 500,000 parts p.a.
Process automation and integration levels
AUTOMATION OF MACHINING
Effects of automation- Cost reducing
(per piece)- Higher
investments- Speed
improvement- Productivity
improvement- Repeatability
improvementC
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CN
C t
ools
FMS
Cam
‘s
Mach
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cost
s (K
c/p
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Productivity (pcs/hour)
Flexibility
next part…
Programming of machine tools
Programming of machines
Machining on CNC machines is controled by a NC code.
NC code is a list of instructions for the machine and also for the operator. Instruction are executed in time order.
NC code must have a specific format so that the control system of machine is able to read it.
Coordinate systems
The tool in machine is moving in workspace.
The position of the tool is given by coordinates.
We are using different coordinate systems.
If we set some coordinates in NC code, the machine moves the tool to the specified place.
Coordinate systems Basic is orthogonal system
X
Y
Z
Coordinate systems - millsZ axis is usually axis of spindle a X axis is
the working axis, or the longest!
XY
Z
Coordinate systems - latheZ axis is usually axis of spindle a X axis is
the working axis – diameter!!!
X
Z
Coordinate systems - multiaxis
To set the position we can add rotation along the axes.
X
Y
Z
A
B
C
Second set of coordinatesU,V,W resp. P,Q,R etc.
Coordinate systém - origin
Refernce point – a specific point on machine with given coordinates. Not always in the workspace of machine.
A special commang G98
Coordinate systems
Ways how to define a movementa) Absolute programing – position is in all
point expressed as a distance from zero-point
b) Incremental programing – position is expressed as a change from last postion
AbsolutG90 X0 Y0 Z50G0 X15 Y70 Z50G1 X15 Y70 Z0G1 X25 Y70 Z0G0 X25 Y70 Z50G0 X0 Y0 Z50
IncrementalG91G0 X15 Y70 Z0G1 X0 Y0 Z-50G1 X25 Y0 Z0G1 X0 Y0 Z50G1 X-45 Y-70 Z0
1.
2.
3.
2.
3.
1.
NC code form
Structure and form of NC code is standardized by international standard - ISO 6983 – Numeric control programs formating
Differences between different control system manufacturers and differences between versions.
NC code structure
Lines (blocks)WordsWord has a meaning and value part
S 1500
ISO nc code and the others
ISO is standardized code (G – code)Some manufacturers devoloped their own
standard for NC code – native standard
Mazak – MazatrolHeidenhein – iTNCSiemens - Sinumeric
NC code structure II.
Heading linesDefinition of relation between coordinate
system of CNC machine and program, type of programing, work mode, working conditions
Program bodyCutting and non-cuting moves, main program
and subprograms, tool changes Ending linesTool return to home point, change to first tool,
coordinates reconstruction
Program sequenceSubprograms A link to another then
the following line is entered into main programm.
This subprogram is executed.
After finishing this program we return to main program a we contiue until end of main program(M30)
Ways of programing
Manual/Hand programing Shopfloor programming Automated programing
Manual programing Editors are used. Program is written
manually (by hand) line after line. Used for simple parts (but complex too) Toolpath is exactly
defined Program can be adjusted
to save time Can use canned cyles Can be parametrized Used in mass production
Manual programingWe need to know the functions: (many more function exist)
Movement functions:G00 rapid movementG01 linear interpolation/movementG02/03 circular interpolation
G40 diameter compensation offG41 diameter compensation on /right handedG42 diameter compensation on /left handed
Support and help functions:M06 tool changeM03/04 spindle start CW/CCWM05 program stopM30 program end
Manual programming
Specilzed editorsPredator G-code editor
G Wizard
Mikronex
Shopfloor programing Somewhere in between manual and
automated Uses cycles with parameters We have to edit these
parameters manually But the NC code
is generated automatically
No postprocessing
Shopfloor programming
Control system use – programming on machine
- No costs (together with machine)- Fast use (macros)- Time waste (program x work)- Comfort (on machine x in office with
PC)- Shape limitations
Heidenhein
Automated programming
Work with the „sequential NC code preparation“
Uses CAM (Computer Aided Manufacturing) software
For all parts including complex shapes We dont need to compute the toolpath We need correct postprocessor
Sequential NC code preparation
Partprogram – workpiece, material, cutting conditions, tools…
Procesor – according to technology
CL data – virtual toolpaths on virtual machine
Postprocesor – „translator“ for the specific CAM-control systém-machine combination
NC code – toolpaths of a real tool on a real machine
Partprogram
Procesor
Postprocesor
CL-data
NC-kód
CAM software
is Computer Aided Manufacturing (machining)
From simple 2-axis turning up to multiaxis machining
Feature or technologically oriented Special types of CAM for special purpose
Live presentation
xD software
2D – just in two axis - turning2,5D – two axis, but in layers – not
simultaneously3D – three axes simultaneouslymultiaxis4D – four axis - one rotary axis (rotary
table)5D – five axis - maching (two rotary axes)
Tool movement programming
CAM software uses „Strategies“Strategy – is a general plan how to
move the tool durign machining
Continual developmentRoughing – offset, raster (Zig-Zag
method) plunging Finishing strategies – pencil milling,
streaming, rest material maching
CAM software developers
NX (Siemens PLM software) Catia (Dassault systémes) – both 10% market share
PowerMill, FeatureCAM, ArtCAM (Delcam company) ,InventorCAM (Autodesk) Wildfire – Pro/Ingineer (PTC) – 5%
EdgeCAM, SurfCAM, SolidCAM, MasterCAM, OneCNC, ESPRIT, GibbsCAM
Simulaton and verification
Simulation is used to control generated toolpaths for following reasons:- Colisions- Undercuts (or rest material)- Postprocesing check
Verification
NX
Automated programing - review
We can do complex shapes, no need to calculate control points
We can use simulation and verification We can change the tool easilyBut We need postprocessor Expensive (SW, computer, learning…) Program is always longer (again
expensive)
What software we will use? ArtCAM
FeatureCAM
Course
Projects- Common – same tasks for all- Individual – own selection of part and
individual work on it. Evaluated.
Test – from theory of automation and programming