1. VOCATIONAL TRAINING
PROJECT
SUBJECT-STUDY OF CNC MACHINE CONTROL
SYSTEM
BY:
PRASHANT KUMAR
GANDHI ENGINEERING COLLEGE BHUBANESWAR
VT20170179
GUIDED BY:
Mr SEKHAR CHAKRABORTY
Sr. Manager, MUEM
Spare Manufacturing Department
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2. ACKNOWLEDGEMENT
I, Prashant Kumar studying in Gandhi Engineering College would like to extend my
heartiest gratitude to the entire TATA STEEL family for having extended their full
support during the course of my training. Everyone at the works were very helpful in
giving me inputs which included information regarding not only my project but also any
other job that I came across during the training.
Thus I have got a lot of exposure and knowledge as to how the largest iron and steel
company, TATA STEEL works.
The employees around the workplace were very friendly and would clarify any doubts
that I had.
I would like to thank:
Mr Sekhar Chakraborty
Mr T.K. Jha
And all the other employees at the IEM office. Without their support this project would
not have been possible.
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3. CONTENTS
ACKNOWLEDGEMENT------------------------------------------------------------------ 1
TATA STEEL------------------------------------------------------------------------------- 4
SMD------------------------------------------------------------------------------------------- 9
NUMERIC CONTROL--------------------------------------------------------------------- 11
CNC-------------------------------------------------------------------------------------------- 12
CNC PLANO MILLER--------------------------------------------------------------------- 16
TECHNICAL DATA OF MACHINE---------------------------------------------------- 18
ELECTRONIC MODULE------------------------------------------------------------------ 27
SERVO MOTOR----------------------------------------------------------------------------- 31
PLC--------------------------------------------------------------------------------------------- 33
POWER SUPPLY CIRCUIT--------------------------------------------------------------- 38
SENSOR-------------------------------------------------------------------------------------- 41
APPLICATION OF CNC------------------------------------------------------------------- 42
ADVANTAGES------------------------------------------------------------------------------ 43
FUTURE OF CNC--------------------------------------------------------------------------- 45
BIBLIOGRAPHY--------------------------------------------------------------------------- 48
WELCOME
TO
TATA STEEL JAMSHEDPUR
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6. HISTORY:
TATA STEEL was the first integrated steel company established in INDIA in 1907.
Its founder was Mr. Jamshedji Nausherwanji Tata. He was a man of honors. He
always strived to bring new ideas to India. It was established in a village named
SAKCHI at that time. The railway station name was KALIMATI. Now that small
village has been changed to a very beautiful steel city known for its cleanliness,
greenery, and of course The TATA STEEL. The village was named JAMSHEDPUR
and the station was TATANAGAR on the name of Mr. J.N.TATA. The main product
of TATA STEEL is iron and steel. It is not very long ago that TATA STEEL was
producing steel about 3 million ton but in current year it’s production is about 9 to
10 million tons of steel out of which 9 million tons is sold. It is due to its well
management and the working skills of its workers. This company has got the best
steel company in the world three times in which two times in adjacent years. A
magazine named World Steel Dynamics declares this.
MILESTONES OF TATA STEEL
1907-Tata Iron& Steel co. was floated
1911-First steel bar made.
1937-Reasarch lab opened
1955-Agreement with Kaiser engineering. For 2MT expansion program.
1973-Amalgamation with west Bokaro LTD. For coal mines
2000-Inauguration of CRM.
2002-VISSION-2007 launched.
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7. 2004-JUSCO formed
2004- First major overseas investment in NatSteel, Singapore.
2005-Capacity increased from 4MT to 5MT. Investment in Millennium Steel, Thailand
2007-Tata Steel acquired the UK-based steel maker Corus.
2008- SAIL and Tata Steel form JV for coal mining in India.
2009- Tata Ryerson and HMPCL merges with Tata Steel.
2010 - Brand migration of CORUS to Tata Steel.
2011 – Construction work begins for first phase of MTPA Greenfield steel project at
Kalinganagar, Odisha.
2012- Facilities setup to increase the capacity of Jamshedpur Steel works to 9.7 MTPA
have been completed.
2013 –Production capacity of Tata Steel ramps up to 9.7 MnTPA.
2014 - Tata Steel launches Ferro Manganese and Ferro Chrome brands.
DEPARTMENTS OF TATA STEEL
From raw material to the final product many units work upon the material. These units
are:-
- Blast furnace
- LD1
- LD2
- CRM
- HSM MILLS
- SINTER PLANT 1,2,3
- MERCHANT MILL
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8. - SM & SPOS
Products:
Tata Steel's products include
1. Hot and cold rolled coils and sheets,
2. galvanized sheets,
3. tubes, wire rods,
4. Construction re-bars rings and bearings.
In an attempt to 'discommodities' steel, the company has introduced
Brands like Tata Steel (the world's first branded Cold Rolled Steel)
Tata Shaktee (Galvanized Corrugated Sheets)
Tata Tiscon (re-bars)
Tata Pipes
Tata Bearings
Tata Agrico (hand tools an implements)
Tata Wiron (galvanized wire products).
The Construction Solution Group explores new avenues for steel utilization by
techniques that are economical, use less natural resources and energy. Tata Steel has
also developed "galvannealed" cold rolled steel with technical assistance from
Nippon steel & Arcelor for high-end auto applications.
In addition to steel, the Company is in the business of diverse products, such as
bearings, capital steel plant equipment and spares, cement, tubes, etc. The captive
mines and collieries located mainly in Bihar and Orissa, supply the finest grades of
feedstock to the steel plant. Customer satisfaction at Tata Steel begins with raw
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9. materials preparations and is meticulously inter-linked by a quality chain at every stage
of its operations.
Tata Steel Safety Rules & Regulation:
Safety Violation inside the works of Tata Steel at Jamshedpur is divided into five parts
as given below:
- Violation of Training & Personal Protective Equipment (PPE).
- Violation of Procedure / Rules.
- Violation of Road Safety.
- Accident / Dangerous Occurrence caused due to negligence.
- Violation of Major Safety / Environmental Standards.
Environment Management:
Jamshedpur was India's first planned industrial township. In more recent times, Tata
Steel has received ISO 14000 certification for environment management for its steel
works. Most of its other, mines and collieries also have been accredited with ISO
certification.
Bearings Divisions: Manufactures ball bearings, double row self-aligning bearings,
clutch release bearings and tapped roller bearing for two wheelers, fans, water
pumps, etc. Ferro Alloys and Minerals Division: Operates chrome mines and has unit
for making Ferro chrome and Ferro manganese. It is one of the largest players in the
global Ferro chrome market.
Rings and Agrico Division: The ring plants manufactures forged and rolled rings for
bearings and automotive components .Tata Agrico is the first organized manufacturer
in India of hand tools and implements for application in agriculture.
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10. Tata Growth Shop (TGS): Has designed, developed, manufacture, erected and
commissioned thousands of tons of equipment ranging from overhead cranes to high
precision components, including a rocket launch pad for the Indian Space and
Research Organization.
Tubes Division: The biggest steel tube manufacturer with the largest market share in
the country, it aspires to strengthen its market presence by expanding and
modernizing its commercial and precision tube manufacturing capacity.
Wire Division: A pioneer in the manufacture of steel wires in India, it produces
coated and uncoated wires, branded as Tata Wiron. The division also operates a
wholly owned subsidiary in Sri Lanka.
VISION OF TATA STEEL:
Managing a global workforce and setting global benchmarks is primarily about
managing diversity. The ability to maximize business opportunities and meet challenges
so that value can be created for stakeholders is something that can be achieved
through a process of inclusive growth, one in which every person contributes to the
blueprint for the future and is truly committed to the stated objectives. And one of the
key requisites for successful diversity management is a shared vision.
The Vision 2012 for the Tata Steel Group was co-created by its people across its various
locations – from Jamshedpur in India, to the United Kingdom, to South East Asia, to the
Netherlands. Driven as much by its commitment to society as by its performance and
profits, the Tata Steel Vision aspires to make the Group the global industry benchmark
for both Value Creation and Corporate Citizenship. The key drivers of the Group Vision
will manifest themselves in the goals and objectives the Group sets for itself in the
coming years. This shared Vision is a call to action for Tata Steel’s people, to work
together to a future that holds a promise of tremendous growth for all its constituents
and the world at large.
SPARES AND MANUFACTURING
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11. DEPARTMENT
This department provides quality spares to the Tata Steel. Some spares are
manufactured & some are out sourced. Other important activities of this department are
assembly of heavy machines & re-conditioning of old &wear out machines. It acts as a
vital unit for other departments of the steel plant for their efficient performance.
This department consists of various sections as listed below:
- Machine Shop
- Welding Shop
- Fabrication Shop
- Forging Shop
- Heat Treatment Section
- Segment Repair Shop
- Planning & Outsourcing section
Machine Shop
- It consists basically lathe ,boring ,milling machine etc
Welding Shop
- It involves the process of reconstructing the worn out rolls by increasing the
diameter of the roll slightly more than the required diameter to make it reusable.
Fabrication Shop
- In fabrication shop bending, straightening of sheets are performed. Cutting of
desired shapes of large iron sheets by LPG and oxygen is also performed by
programming techniques.
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12. Heat Treatment Shop
- It involves heating or chilling normally to extreme temperature to achieve
hardening and softening of material. Basically property of material is altered.
Some of the machines available in the shops are:
Machine shop
- Skoda conventional horizontal boring machine- M/C #249, #253, #254, #257,
#259
- Skoda CNC horizontal boring machine - M/C #252, #255, #256, #258, #260
- CNC Plano miller - M/C #449
- CNC Grinding machine - M/C #347
- Conventional lathe machine
- Without turret
- With turret- M/C #172, #180
- CNC lathe machine - M/C #89, #94, #97, #106
- CNC Vertical boring machine - M/C #178
Welding shop
- Gas Arc Welding machine
- Submerged Arc Welding machine
- Fabrication shop
- Sheet Bending machine
- Sheet Straight machine
- Sheet Shearing machine
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13. - CNC based Profile Gas Cutting machine
- Perforating machine
Forging shop
- Davy Press
- Steam Hammer
- Pneumatic Hammer
- Gear Turning machine
- Furnace
Heat Treatment Shop
- Gas furnace (BOFCO #1, #2; NSR; WESMAN #1, #2)
- Electrical furnace (BOFCO Tempering, NGC)
WHAT IS NUMERIC CONTROL?
Numerical control has been defined by the Electronic industries association (EIA) as a
system in which the actions are controlled by the direct insertion of numerical data at
some point. Numerical control can be considered as a versatile form of programmable
automation in which the machine tool is controlled by a series of coded instructions
consisting of letters, numbers, punctuation marks, and others symbol .These codes are
converted into two types of control signals; pulses of electric output signals and on/off
control signals.
TYPES OF NUMERIC CONTROL
- DIRECT NUMERIC CONTROL (DNC)
- COMPUTER NUMERIC CONTROL (CNC)
DIRECT NUMERIC CONTROL
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14. - In mid-1960’s Cincinnati Milaron and GE independently proved the feasibility
of the concept of DNC, in which machine are operated directly from remote
computer. A computer located at about 3000 feet from hard wired NC milling
machine successfully transmitted instructions to the MCU via a telephone line.
The DNC systems were primarily used to download part programs to NC
machines.
COMPUTER NUMERIC CONTROL
- In contrast to remote controlled concept of DNC, the idea of CNC is to position
a computer right at machine .The emergence of integrated –circuit
minicomputers and lower cost CRT’s brought the CNC concept into reality. A
dedicated computer is built into the MCU to control one machine tool. Nearly
all NC machine tools are of type CNC type. Today’s computer technology
provides CNC system with a higher level of stored intelligence right at machine
with a convenient editing capability and memory capacity for part programs
storage.
COMPUTER NUMERIC CONTROL
Computer Numerical Control (CNC) is one in which the functions and motions of a
machine tool are controlled by means of a prepared program containing coded
alphanumeric data. CNC can control the motions of the work piece or tool, the input
parameters such as feed, depth of cut, speed, and the functions such as turning spindle
on/off, turning coolant on/off.
HISTORY OF CNC
- First concept was given by Mr John T Parson in 1942
- 1949 US Air Force asks MIT to develop a "numerically controlled" machine
- 1952 Prototype NC machine demonstrated (punched tape input)
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15. - 1980-CNC machines (computer used to link directly to controller)
- 1990-DNC: external computer “drip feeds” control programmer to machine tool
controller
CLASSIFICATION OF CNC
A large variety of components are manufactured in industries and every component has
its own geometric parameters and hence different machining requirements. For meeting
the machine requirements of different components, a single CNC system cannot give
optimum results. So, the CNC machines are designed to meet specific requirements to
make them cost effective.
BASED ON FEEDBACK CONTROL
- Open Loop Control System
- Closed Loop Control System
BASED ON CONTROL SYSTEM FEATURES
- Point to Point Control System
- Straight Line Control System
- Continuous path control system
OPEN LOOP CONTROL SYSTEM
- The open-loop control means that there is no feedback and uses stepping motors.
A stepping motor is a device whose output shaft rotates through a fixed angle in
response to an input pulse. In the open-loop system, the electric motor continues
to run until the absence of power, from input command signal, indicating that
the programmed location has been attained. There is no monitoring of the actual
displacement of the machine slide
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16. CLOSED LOOP CONTROL SYSTEM
- The closed-loop systems are characterized by the presence of feedback devices
in the system. In a closed-loop control system, the actual output from the system
i.e., actual displacement of the machine slide, is compared with the input signal.
Encoder is used as a feedback element that gives the information about the
distance travelled by the device .Encoder is mounted on the motor.
POINT TO POINT CONTROL SYSTEM
- Point-to-point control is one where accurate positional control is required only
to place the machine slides in fixed position and the machine tool slide is
required to reach a particular fixed coordinate point in the shortest possible
time. The machining operations are performed at specific points and there is no
machining while the machine slides move from one point to the next. Point-to-
point system is suitable for drilling, boring, tapping, punch presses and jig
boring machines.
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17. STRAIGHT LINE CONTROL SYSTEM
- Straight line or straight cut CNC system is an extension of point-to-point control
system with the provision of machining along a straight line as in the case of
milling and turning operations. This is obtained by providing movement at
controlled feed rate along the axis in the line of motion.
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18. CONTINOUS PATH CONTROL SYSTEM
- The contouring system is a high technology and most versatile control systems.
The contouring system generates a continuously controlled motion of the tool
and work piece along different coordinate axes. This control system enables the
machining of profiles, contours and curved surface. In contouring system, the
movement of several machine slides has to be controlled simultaneously so that
their relative positions and velocities are established at every point and
continuously throughout the operation.
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19. WORKING OF CNC
- In CNC applications, both position and velocity must be controlled.
The tachometer an analog type transducer, is normally used to measure the
velocity. Resolvers and encoders are employed to measure position and
sometime velocity. Resolvers are analog where encoders are digital.
A comparator compares the reference and feedback signals for each axis and
then sends an error signal to the drive amplifier. The drive amplifier is used
because the command error signal to drive error signal itself is not large enough
to drive a servo motor .The amount of command signal magnification is called
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20. gain loop or loop gain. The velocity feedback loop consists of a comparator an
amplifier, a tachometer attached to either lead screw or the servomotor, and a
tachometer interface including signal filter & amplifier. This can be regarded as
a sub loop within the position feedback loop.
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25. FRONT VIEW OF THE MACHINE
TECHNICAL DATA OF MACHINE
Dimension of mould broad face water jackets
- 5500mm x 1100mm x 1100mm
Dimension of narrow face including support plate
- 1100mm x 100mm x 400mm
Dimension of the machine
- Total length-7000mm
- Total height above floor-3500mm
- Total width-3100 mm
- length of machine table-5500 mm
- Width of machine table-2000mm
Load of the machine-10 ton
Milling accuracy- 0.02mm (3 axis)
Driving power of main motor - 18.5KW
Speed range of milling spindle - 40-3200/min (step less)
Tool clamping - automatically
Tool changing - pick up, 2 tools
Spray cooling device
- Medium- water –oil emulsion
- Consumption- 0-269 g/min
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27. COPPER MOULD
Job related information:-
In machine#449 machining of copper couplings are done. Machining of copper
couplings are required because copper being a soft metal wears out and does not
meet the contact requirements. Thus it is brought back to the machine where a slight
machining is done to bring the copper back in the open so that the coupling can
work properly. One would say that this could be done in any other machine too, why
use such a big, high cost machine. The machining that is needed to be done on the
machine requires a tolerance level of not more than 0.005mm. This kind of accuracy
can only be provided with this kind of machine
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28. Machine table design in T-slotted fixed plate:
Length of machine plate 5500mm
Width of machine plate 2000 mm
Machine portal:
Traverse motion of the portal on the machine in x axis 4000mm
Electrical equipment:
Including cables between operating desk (with integrated switch cabinet)
And machine
Size of operating desk 1200 x 900 x 1300 mm
Speed power and feed displays
Diagnosis display of the machine in plain text
1complete 3-axis CNC control
Product: Siemens SINUMERIK 840 D in basic design
Functional description:
- The machine is set in to operation by actuating the main switch provided at the
operator’s desk. After actuation of main switch, the machine can be ready for by
means of key operated switch and the luminous push button located in the CNC
operating panel. The line should be stopped via emergency switch in emergency
situation, in this case main switch is taken out.
The emergency switch are positioned
- On the operating panel of control desk
- On the left and right of the machine portal
- On the operator pendant
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29. When the procedures described above have been carried out, the machine is” ready for
operation. The operation of CNC milling machine is affected by means of the operating
elements provided in the CNC operating panel and the manually operated desk.
OPERATING PANEL
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30. MACHINE #449
COMPONENT AND DETAILS
1. ZK2-A11 Active Interface Module 36kw 3AC 380-480V 58A 50/60Hz
2. M01- all SINUMERIK CPU
3. K2-A21 Active Line Module
Input-3AC 380-480V 50/60Hz
Output-DC 600V 60A 36KW
4. K2-A31 Single Motor Module
Input-DC 600V
Output-3AC 400V 60A
5. K2-A51 Single Motor Module
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31. MACHINE #449
COMPONENT AND DETAILS
1. ZK2-A11 Active Interface Module 36kw 3AC 380-480V 58A 50/60Hz
2. M01- all SINUMERIK CPU
3. K2-A21 Active Line Module
Input-3AC 380-480V 50/60Hz
Output-DC 600V 60A 36KW
4. K2-A31 Single Motor Module
Input-DC 600V
Output-3AC 400V 60A
5. K2-A51 Single Motor Module
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32. Input- DC 600Vigat
Output- 3AC 400V 60A
6. K2-A71 Double Motor Module
Input-Dc 600V
Output-3AC 400V 9A
7. Relays
Siemens-SIRIUS AC15-230V 3A DC13-24V 1A
A1/A2-AC/DC 24V 0.75W
No. of axes in the machine- 3
- X-axis
- Y-axis
- Z-axis
- A fixed spindle
Connection module- Basic PN
- Operating Temperature – 0-55degrees Celsius
- Supply – 24V DC 4.4A
- Digital Output- 24V DC 0.5A
Protective Device – M21, F324
- AC Rated Voltage- 230V 50Hz
- Rated current- 5.4A
- Starting Current-12A
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34. - 230V/3A
- 24V/1A
FUSE
- SIEMENS
- 80A
- 500V
- 120Ka
Motor Lubrication
- X,Y,Z axis -3ph AC 70 W 400V
Motor Hydraulics
- 3ph AC 400V 180W
Motor Fan Spindle
- 3ph AC 400V 0.37A
Limit SWS
- XYZ 24V DC
Wiring colour
400V AC Rated Power -BLACK
230V AC Basic Control -RED
24V DC Basic Control -BLUE
Measuring Values - GRAY
Pre Main Switch -VIOLET
Interlock - ORANGE
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35. CNC controlled special milling machine
Type double column milling machine
This double-column milling machine is if special design for the re-machining of CSP
mould copper plates.
The double-column milling machine consist of following units:-
- Machine table in design of T-slotted fixed plates with guide ways and telescopic
covers.
- Machine portal with feed gears.
- Milling carriage in slide design
- Complete electrical equipment
- CNC- control , type SINUMERIK 840 D sl
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36. REAR PANEL VIEW {Diagram}:
ELECTRONIC MODULE
- Active Interface Module 36KW
- Single Motor Module 60 Amp for Spindle Drive
- Single Motor Module 18Amp for Y Axis
- Double Motor Module 2x 9Amp for X & Z Axis
- Active line Module 36KW
- Siemens HT2 Interface Module
Active Interface Module
The input to active interface module is a 440 V, 3 phase raw AC .Output obtained is
also AC after filtering the harmonics from the power supply. As a result sinusoidal
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37. current is drawn from the feeding mains and hence causing no harm to the feeding
circuit. The output voltage is given to active line module.
NC Unit
It is the numeric control unit that are operated by precisely programmed commands. It
is meant to control the motion along multiple axes acting as the CPU.
Active Line Module
The 3 phase output AC voltage from the active interface module acts as input to it and
produces a regulated DC output voltage that is finally given to all the spindle and motor
modules.
Single Motor Module
The Single Motor Module is the Drive for Spindle Motor.
Single Motor Module
The Single Motor Module is the Drive for Y–Axis Motor.
Double Motor Module
The Double Motor Module is the Drive for X-Axis and Z-Axis Motor.
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39. SCHEMATIC DIAGRAM OF CONNECTIONS OF DRIVE AND
AXES
DRIVE TOPOLOGY
- NCU 710
- INFEED 1
- Spindle
- Y axis
- X Axis
- Z Axis
MOTOR DETAILS
- Spindle : Asynchronous Motor 22 KW, 4500 rpm, 57A, 140.1 NM
- Y Axis : Synchronous Motor 4.55 KW, 3000 rpm, 8.5A, 20 NM
- X Axis : Synchronous Motor 3.24 KW, 3000 rpm , 6.6A, 13 NM
- Z Axis : Synchronous Motor 2.39 KW 3000 rpm, 5.2A, 9 NM
OTHER MOTORS
- Lubrication Unit : 70W
- Hydraulic Unit : 180W
- Spindle Fan : 37A
ENCODER
An encoder is a sensor of mechanical motion that generates digital signals in response
to motion. There are two different types of encoder: linear and rotary. A linear encoder
responds to motion along the path but rotary encoder responds to rotational motion.
CNC used in machine #449 uses absolute rotary encoder. They act as feedback device.
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40. Nowadays encoder are mounted on the motor itself to give precise value. It gives both
velocity and position feedback.
BLOCK DIAGRAM OF CNC CONTROL
WORKING OF ENCODER
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41. In an encoder is used to check the movement of the motor. The light source is used as a
reference and a photovoltaic cell is used to generate square wave pulses. The output is
directly given to the CNC which then contacts the drive to either increase or decrease
the speed of the motor. The motors used in this machine are servo motor
SERVO MOTOR
Servo implies an error sensing feedback control which is utilized to correct the
performance of a system. It also requires a generally sophisticated controller, often a
dedicated module designed particularly for use with servomotors. Servo motors are DC
motors that allows precise control of angular position. The servo motors have a
revolution cut-off of 90 to 180 degrees. But servo motors do not rotate continuously.
Their rotation is limited between angles.
A servo motor is an assembly of four things
- A normal DC motor
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42. - A gear reduction unit
- A position sensing device(tachometer or encoder)
- Control circuit
The DC motor is connected with a gear mechanism which provides feedback to a
position sensor which is mostly a potentiometer. From this e gear box, the output of the
motor is delivered via servo spline to the servo arm. For standard servo motors, the
gear is normally made up of plastic whereas for high power servos, the gear is made up
of metal.
A servo motor consists of three wires:
- a black wire connected to ground
- a white/yellow wire connected to control unit
- a red wire connected to power supply
Working of Servo Motor
The DC motor gets powered from a battery and run at high speed and low torque. The
gear and shaft assembly connected to the DC motors lowers this speed into sufficient
speed and higher torque. The position sensor senses the position of the shaft from its
definite position and feeds the information to the control circuit. The control circuit
accordingly decodes the signal from the position sensor and compares the actual
position of the motors with the desired position and accordingly controls the direction
of rotation of the DC motor to get the required position. The servo motor generally
requires DC supply of 4.8V to 6V
Controlling of a Servo Motor
42
43. - A servo motor is controlled by controlling its position using Pulse Width
Modulation Technique (PWM) the width of the pulse applied to the motor is
varied and send for fixed amount of time. The pulse width determines the
angular position of the servo motor.
OVERVIEW OF SIEMENS SERVODRIVE
- SIMODRIVE is a family of drives, including servo and spindle converters and
motors, designed to meet the needs of modern Machine Tools and Production
Machines. Siemens' SIMODRIVE modular converters and rotary and linear
motors can be combined to form complete drive solutions. SIMODRIVE range of
drives has been designed especially to be combined with the SINUMERIK CNC
controls. Such combination will guarantee you high contour precision and short
downtimes. The SIMODRIVE 611 drive is a transistor pulse converter with
compact modular system with a digital link in a 50mm grid system. SIMODRIVE
611 us compact in size but with a high power density. SIMODRIVE and
SINUMERIK have a longstanding reputation for top quality workpiece
machining to live up to. These two products have been in use almost everywhere
in industry for more than 30 years. Machine Tools and Production Machines
can be equipped with feed motors, closed loop control main spindle motors and
standard asynchronous motors. Siemens range of servomotors have a low of
moment inertia and therefore operate with high dynamics and always produce
maximum torque even at zero speed.
The 1FT6, 1FK6/1FK7 three-phase feed motors, the 1FN3 linear motors and the
1PH7 three-phase main spindle motors are tailored perfectly to the
SIMODRIVE 611
ADVANTAGES
- HIGHLY EFFICIENT
- RESERVES POWER FOR EMERGENCIES
- RESERVES TORQUE
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44. - MOTOR REMAINS COOL AS CURRENT DRAWN IS PROPORTIONAL TO
LOAD
- NO NOISE EVEN AT HIGH SPEED
- FREE OF VIBRATIONS AND RESONANCE
DISADVANTAGES
- SAFETY CIRCUITS REQUIRED
- OVERLOAD DAMAGES MOTOR
- COOLING IS REQUIRED
PLC
Many control technologies are available for control. Early control systems relied upon
mechanisms and electronics to build controlled system. Most modern controllers use
a computer to achieve control. The most flexible of these controllers is the PLC
(Programmable Logic Controller). Designing software for control systems is difficult.
Experienced control engineers have learned many techniques that allow them to solve
problems. This study material helps to understand present methods for designing
controls software using Programmable Logic Controllers (PLCs).
Participants will be able to quickly write controls programs that work as expected (and
avoid having to learn by costly mistakes.)
PROGRAMMABLE LOGIC CONTROLLERS:
INTRODUCTION
A PLC (i.e. Programmable Logic Controller) is a device that was invented to replace
the necessary sequential relay circuits for machine control. The PLC works by looking
at its inputs and depending upon their state, turning on/off its outputs. The user enters a
program, usually via software, that gives the desired results. PLCs are used in many
"real world" applications. If there is industry present, chances are good that there is a
plc. present. If you are involved in machining, packaging, material handling,
automated assembly or countless other industries you are probably already using them.
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45. If you are not, you are wasting money and time. Almost any application that needs some
type of electrical control has a need for a plc.
For example, let's assume that when a switch turns on we want to turn a solenoid on for
5 seconds and then turn it off regardless of how long the switch is on for. We can do this
with a simple external timer. But what if the process included 10 switches and
solenoids? We would need 10 external timers. What if the process also needed to count
how many times the switches individually turned on?
We need a lot of external counters. As you can see the bigger the process the more of a
need we have for a PLC. We can simply program the PLC to count its inputs and turn
the solenoids on for the specified time. PLCs have been gaining popularity on the
factory floor and will probably remain predominant for some time to come. Most of this
is because of the advantages they offer.
• Cost effective for controlling complex systems.
• Flexible and can be reapplied to control other systems quickly and easily.
• Computational abilities allow more sophisticated control.
• Trouble shooting aids make programming easier and reduce downtime.
• Reliable components make these likely to operate for years before failure.
Ladder Logic:
- Ladder logic is the main programming method used for PLCs. As mentioned
before, ladder logic has been developed to mimic relay logic. Modern control
systems still include relays, but these are rarely used for logic. A relay is a
simple device that uses a magnetic field to control a switch. Modern
control systems still include relays, but these are rarely used for logic. A relay is
a simple device that uses a magnetic field to control a switch, as pictured in
following figure. When a voltage is applied to the input coil, the resulting
current creates a magnetic field. The magnetic field pulls a metal switch (or
reed) towards it and the contacts touch, closing the switch. The contact that
closes when the coil is energized is called normally open. The normally closed
contacts touch when the input coil is not energized. Relays are normally drawn
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46. in schematic form using a circle to represent the input coil. The output contacts
are shown with two parallel lines. Normally open contacts are shown as two
lines, and will be open (non-conducting) when the input is not energized.
Normally closed contacts are shown with two lines with a diagonal line through
them. When the input coil is not energized the normally closed contacts will be
closed (conducting).
Relays
- Now that we understand how the PLC processes inputs, outputs, and the
actual program we are almost ready to start writing a program. But first let’s
see how a relay actually works. After all, the main purpose of a plc. is to replace
"real-world" relays. We can think of a relay as an electromagnetic switch. Apply
a voltage to the coil and a magnetic field is generated. This magnetic field sucks
the contacts of the relay in, causing them to make a connection. These contacts
can be considered to be a switch. They allow current to flow between 2 points
thereby closing the circuit.
A DC relay can be used to control an AC circuit. That's the fun of relays!
Replacing Relays
- Next, let’s use a plc. in place of the relay. (Note that this might not be very
cost effective for this application but it does demonstrate the basics we need.)
The first thing that's necessary is to create what's called a ladder diagram. After
seeing a few of these it will become obvious why it’s called a ladder diagram.
We have to create one of these because, unfortunately, a plc. doesn't
understand a schematic diagram. It only recognizes code. Fortunately most
PLCs have software which convert ladder diagrams into code. This shields us
from actually learning the plc.’s code.
First step- We have to translate all of the items we're using into symbols the plc
understands. The plc doesn’t understand terms like switch, relay, bell, etc. It prefers
input, output, coil, contact, etc. It doesn’t care what the actual input or output device
actually is. It only cares that it’s an input or an output. The PLC mainly consists of a
CPU, memory areas, and appropriate circuits to receive input/output data. We can
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47. actually consider the PLC to be a box full of hundreds or thousands of separate relays,
counters, timers and data storage locations. Do these counters, timers, etc. really exist?
No, they don't "physically" exist but rather they are simulated and can be considered
software counters, timers, etc. These internal relays are simulated through bit locations
in registers.
INPUT RELAYS-(contacts) these are connected to the outside world. They physically
exist and receive signals from switches, sensors, etc. Typically they are not relays but
rather they are transistors.
INTERNAL UTILITY RELAYS-(contacts) These do not receive signals from the
outside world nor do they physically exist. They are simulated relays and are what
enables a PLC to eliminate external relays. There are also some special relays that are
dedicated to performing only one task. Some are always on while some are always off.
Some are on only once during power-on and are typically used for initializing data that
was stored.
COUNTERS-These again do not physically exist. They are simulated counters and they
can be programmed to count pulses. Typically these counters can count up, down or
both up and down. Since they are simulated they are limited in their counting speed.
Some manufacturers also include high-speed counters that are hardware based. We can
think of these as physically existing. Most times these counters can count up, down or up
and down.
TIMERS-These also do not physically exist. They come in many varieties and
increments. The most common type is an on-delay type. Others include off-delay and
both retentive and non-retentive types. Increments vary from 1ms through 1s.
OUTPUT RELAYS-(coils) these are connected to the outside world. They physically
exist and send on/off signals to solenoids, lights, etc. They can be transistors, relays, or
trials depending upon the model chosen.
DATA STORAGE-Typically there are registers assigned to simply store data. They
are usually used as temporary storage for math or data manipulation. They can also
typically be used to store data when power is removed from the PLC. Upon power-up
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48. they will still have the same contents as before power was removed. Very convenient
and necessary!!
PLC Hardware modules/cards
The most essential hardware module/cards/components are:
- Power Supply: This can be built into the PLC or be an external unit. Common
voltage levels required by the PLC (with and without the power supply) are
24Vdc, 120Vac, 220Vac.
CPU (Central Processing Unit) - This is a computer where ladder logic is
stored and processed.
I/O (Input/Output) - A number of input/output terminals must be provided so that the
PLC can monitor the process and initiate actions.
INPUTS AND OUTPUTS:
Inputs to, and Outputs from, a PLC are necessary to monitor and control a process.
Both inputs and outputs can be categorized into two basic types: logical or continuous.
Consider the example of a light bulb. If it can only be turned on or off, it is
logical control. If the light can be dimmed to different levels, it is continuous.
Continuous values seem more intuitive, but logical values are preferred because they
allow more certainty, and simplify control. As a result most controls
applications (and PLCs) use logical inputs and outputs for most applications. Outputs
from PLCs are often relays, but they can also be solid state electronics such as
transistors for DC outputs or Triacs for AC outputs. Continuous outputs require special
output cards with digital to analog converters. Outputs to actuators allow a PLC to
cause something to happen in a process.
Solenoid Valves - logical outputs that can switch a hydraulic or pneumatic flow.
Motor Starters - motors often draw a large amount of current when started, so they
require motor starters, which are basically large relays.
Servo Motors - a continuous output from the PLC can command a variable speed or
position.
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49. Inputs come from sensors that translate physical phenomena into electrical
signals. Typical examples of sensors are listed below in relative order of popularity.
- Lights - logical outputs that can often be powered directly from PLC output
boards.
- Indicator lights: These indicate the status of the PLC including power on,
program running, and a fault. These are essential when diagnosing problems.
- Proximity Switches - use inductance, capacitance or light to detect an object
logically.
- Switches - mechanical mechanisms will open or close electrical contacts for a
logical signal.
- Potentiometer - measures angular positions continuously, using resistance.
- LVDT (linear variable differential transformer) - measures linear displacement
continuously using magnetic coupling.
Inputs for a PLC come in a few basic varieties, the simplest are AC and DC inputs.
Sourcing and sinking inputs are also popular. This output method dictates that a device
does not supply any power. Instead, the device only switches current on or off, like a
simple switch. In smaller PLCs the inputs are normally built in and are specified
when purchasing the PLC. For larger PLCs the inputs are purchased as modules, or
cards, with 8 or 16 inputs of the same type on each card. For discussion purposes we
will discuss all inputs as if they have been purchased as cards. The list below shows
typical ranges for input voltages, and is roughly in order of popularity.
12-24 DC, 100-120 Vac. 10-60 DC, 12-24 Vac/dc, 5 DC (TTL), 200-240 Vac, 24 DC.
POWER SUPPLY CIRCUIT
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50. Power supply of:
- Panel
- Fault lamp
- Sinamics S7
- Digital input
- 24 V conventional
- Sinamics (drive)
- Digital output
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52. PLC DETAILS
- CPU
- Power Supply
- Profisafe
- DI(digital input) Card
- AI(analog input) Card
- DO(digital output) Card
- I/F Module (standard and high feature
- CPU –Central Processing Unit
Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually
one of the microcontrollers. CPU also takes care of communication, interconnectedness
among other parts of PLC controller, program execution, memory operation,
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53. overseeing input and setting up of an output. CPU unit makes a great number of check-
ups of the PLC controller itself so eventual errors would be discovered early.
Power Supply
- Mostly PLC controllers work either at 24V DC or 220 V AC. On some PLC find
electrical supply is given as a separate module. User has to determine how much
current to take from I/O module to ensure that electrical supply provides
appropriate amount of current. Different types of modules use different amounts
of electrical current.
Profisafe: Secure communication
- It was the first communication standard that provides both standard and safety-
related communication on one bus line. Saving potential property.
Axis Monitoring Functions
Comprehensive monitoring functions are present in the control for protection of people
and machines
- Contour monitoring
- Position monitoring
- Zero Speed monitoring
- Clamping monitoring
- Speed set point monitoring
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54. - Actual velocity monitoring
- Limit switches monitoring
- Monitoring of working area limitations(Protection Zones)
SENSORS
- INDUCTIVE SENSOR
There are six no. of inductive sensors in machine which are grouped in two
categories:
Spindle stop Reference x-axis
Tool clamp Reference y-axis
Tool unclamp Reference z-axis
- PREMIERE SWITCH
- Lubrication switch for x,y,z axis
- Hydraulic switch
- LEVEL SWITCH
- Level switch cool lubrication
- TEMPERATURE SENSOR
OVERVIEW ABOUT THE TECHNOLOGY
- Drive- based modular CNC
- Multi-technology CNC
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55. - Up to 93 axes/spindles
- Up to 30 machining channels
- Modular panel concept
- Up to 19” colour display
- SINMATIC S7 -300 PLC
BENEFITS OF 840DSL
Modular and scalable. It can be ideally adjusted to operator’s philosophy applied by
state of art premium machine concept. It is a benchmark in open architecture. Its open
system architecture is unique. CNC can be optimally adjusted to machine technology
and shows high degree of performance in production automation. Communication at all
levels. With PROFINET, the 840D SL performs excellent communication from
production to manufacturing and execution level.
ADVANTAGES
- Easier to program
- Easy storage of existing programs
- Easy to change a program
- Avoids human errors
- NC machines are safer to operate
- Complex geometry is produced as cheaply as simple ones
- Usually generates closer tolerances than manual machines
LIMITATIONS
- High initial investment
- High maintenance requirement
- Not cost effective for low production levels
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56. APPLICATIONS OF CNC
- Chip Removal
- Fabrication
- Grinding
- Unconventional Machining
- Special Purpose Applications
FUTURE OF CNC TECH
Processors. Today CNC use fast processor and multiprocessor systems. The CNC’s use
64-bit processor and coprocessor with a 64-bit communication bus. The use of faster
processors provides high clock frequency Up to 60 MHz for executing instruction. The
use of zero wait RAM permits stored part programs and data to be transmitted in a
single tick of the microprocessor clock. Multifunction CNC machine have gradually
gained popularity. This feature allows a complicated work piece requiring both turning
and milling operation to be produced in one machine set up. Communication is the key
element in connecting CNC to manufacturing system. New CNC control should have the
capabilities of distributive numerical control, status reporting, tool management, work
scheduling and I/O communication. Small size and affordability .Many manufacture
plants are beginning to use small CNC machine tool to produce the small work pieces.
These CNC machines are less expensive and are affordable to manufactures.
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57. BIBLIOGRAPHY:
• www.tatasteel.com
• Google.com
I am very great full for my project help without you help sir I wouldn’t
complete my project thankyou Mr Sekhar Chakraborty and Mr T. K. Jha
sir.
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