Projeect Report

8/3/2019 Projeect Report

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PROJEECT REPORT

Project Development of PLC program for a lathemachine

Name-Amit Kumar

Section-RE28T3B41

Regd.No.-10800433


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CONTENT

BHEL- AN Overview

Introduction to manual lathe

Operation of a lathe

Disadvantage of hard wired logic

CNC machine

Introduction to PLC

I/O devices


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BHELAN OVERVIEW

BHEL is the largest engineering and manufacturing enterprise in India in the energy related

infrastructure sector today. BHEL was established more than 40 years ago when its first plant

was setup in Bhopal ushering in the indigenous Heavy Electrical Equipment Industry in India a

dream which has been more than realized with a well recognized track record of performance it

has been earning profits continuously since 1971-72.

BHEL caters to core sectors of the Indian Economy viz., Power Generation's & Transmission,

Industry, Transportation, Telecommunication, Renewable Energy, Defense, etc. The wide

network of BHEL's 14 manufacturing division, four power Sector regional centres, over 150

project sites, eight service centres and 18 regional offices, enables the Company to promptly

serve its customers and provide them with suitable products, systems and services efficiently

and at competitive prices. BHEL has already attained ISO 9000 certification for quality

management, and ISO 14001 certification for environment management.

POWER GENERATION

Power generation sector comprises thermal, gas, hydro and nuclear power plant business as of

31.03.2001, BHEL supplied sets account for nearly 64737 MW or 65% of the total installed

capacity of 99,146 MW in the country, as against nil till 1969-70.

BHEL has proven turnkey capabilities for executing power projects from concept to

commissioning, it possesses the technology and capability to produce thermal sets with super

critical parameters up to 1000 MW unit rating and gas turbine generator sets of up to 240 MW

unit rating. Co-generation and combined-cycle plants have been introduced to achievehigher plant efficiencies. to make efficient use of the high-ash-content coal available

in India, BHEL supplies circulating fluidized bed combustion boilers to both thermal and

combined cycle power plants.

The company manufactures 235 MW nuclear turbine generator sets and has commenced


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production of 500 MW nuclear turbine generator sets.

Custom made hydro sets of Francis, Pelton and Kapian types for different head discharge

combination are also engineering and manufactured by BHEL.

In all, orders for more than 700 utility sets of thermal, hydro, gas and nuclear have been placed

on the Company as on date. The power plant equipment manufactured by BHEL is based on

contemporary technology comparable to the best in the world and is also internationally

competitive.

The Company has proven expertise in Plant Performance Improvement through renovation

modernisation and uprating of a variety of power plant equipment besides specialised know how

of residual life assessment, health diagnostics and life extension of plants.

POWER TRANSMISSION & DISTRIBUTION (T & D)

BHEL offer wide ranging products and systems for T & D applications. Products manufactured

include power transformers, instrument transformers, dry type transformers, series and stunt

reactor, capacitor tanks, vacuum and SF circuit breakers gas insulated switch gears and

insulators.

A strong engineering base enables the Company to undertake turnkey delivery of electric

substances up to 400 kV level series compensation systems (for increasing power transfer

capacity of transmission lines and improving system stability and voltage regulation), shunt

compensation systems (for power factor and voltage improvement) and HVDC systems (for

economic transfer of bulk power). BHEL has indigenously developed the state-of-the-art

controlled shunt reactor (for reactive power management on long transmission lines). Presently a

400 kV Facts (Flexible AC Transmission System) project under execution.

INDUSTRIES

BHEL is a major contributor of equipment and systems to industries, cement, sugar, fertilizer,

refinances, petrochemicals, paper, oil and gas, metallurgical and other process industries. The

range of system & equipment supplied includes: captive power plants, co-generation plants DG

power plants, industrial steam turbines, industrial boilers and auxiliaries. Wate heat recovery


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boilers, gas turbines, heat exchangers and pressure vessels, centrifugal compressors, electrical

machines, pumps, valves, seamless steel tubes, electrostatic precipitators, fabric filters, reactors,

fluidized bed combustion boilers, chemical recovery boilers and process controls.

The Company is a major producer of large-size thruster devices. It also supplies digitaldistributed control systems for process industries, and control & instrumentation systems for

power plant and industrial applications. BHEL is the only company in India with the capability

to make simulators for power plants, defense and other applications.

The Company has commenced manufacture of large desalination plants to help augment the

supply of drinking water to people.

TELECOMMUNICATIONBHEL also caters to Telecommunication sector by way of small, medium and large switching

systems.

RENEWABLE ENERGY

Technologies that can be offered by BHEL for exploiting non-conventional and renewable

sources of energy include: wind electric generators, solar photovoltaic systems, solar lanterns

and battery-powered road vehicles. The Company has taken up R&D efforts for development ofmulti-junction amorphous silicon solar cells and fuel based systems.

INTERNATIONAL OPERATIONS

BHEL has, over the years, established its references in around 60 countries of the world, ranging

for the United States in the West to New Zealand in the Far East. These references encompass

almost the entire product range of BHEL, covering turnkey power projects of thermal, hydro

and gas-based types, substation projects, rehabilitation projects, besides a wide variety of

products, like transformers, insulators, switchgears, heat exchangers, castings and forgings,

valves, well-head equipment, centrifugal compressors, photo-voltaic equipment etc. Apart from

over 1110MW of boiler capacity contributed in Malaysia, and execution of four prestigious

power projects in Oman, Some of the other major successes achieved by the Company have been

in Australia, Saudi Arabia, Libya, Greece, Cyprus, Malta, Egypt, Bangladesh, Azerbaijan, Sri


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Lanka, Iraq etc.

The Company has been successful in meeting demanding customer's requirements in terms of

complexity of the works as well as technological, quality and other requirements viz extended

warrantees, associated O&M, financing packages etc. BHEL has proved its capability toundertake projects on fast-track basis. The company has been successful in meeting varying

needs of the industry, be it captive power plants, utility power generation or for the oil sector

requirements. Executing of Overseas projects has also provided BHEL the experience of

working with world renowned Consulting Organisations and inspection Agencies.

In addition to demonstrated capability to undertake turnkey projects on its own, BHEL possesses

the requisite flexibility to interface and complement with International companies for large

projects by supplying complementary equipment and meeting their production needs for

intermediate as well as finished products.

The success in the area of rehabilitation and life extension of power projects has established

BHEL as a comparable alternative to the original equipment manufactures (OEMs) for such

plants.

TECHNOLOGY UPGRADATION AND RESEARCH & DEVELOPMENT

To remain competitive and meet customers' expectations, BHEL lays great emphasis on the

continuous upgradation of products and related technologies, and development of new products.

The Company has upgraded its products to contemporary levels through continuous in house

efforts as well as through acquisition of new technologies from leading engineering

organizations of the world.

The Corporate R&D Division at Hyderabad, spread over a 140 acre complex, leads BHEL's

research efforts in a number of areas of importance to BHEL's product range. Research and

product development centers at each of the manufacturing divisions play a complementary role.

BHEL's Investment in R&D is amongst the largest in the corporate sector in India. Products

developed in-house during the last five years contributed about 8.6% to the revenues in 2000-

2001.


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BHEL has introduced, in the recent past, several state-of-the-art products developed in-house:

low-NQx oil / gas burners, circulating fluidized bed combustion boilers, high-efficiency Pelton

hydro turbines, petroleum depot automation systems, 36 kV gas-insulated sub-stations, etc. The

Company has also transferred a few technologies developed in-house to other Indian companies

for commercialisation.

Some of the on-going development & demonstration projects include: Smant wall blowing

system for cleaning boiler soot deposits, and micro-controller based governor for diesel-electric

locomotives. The company is also engaged in research in futuristic areas, such as application of

super conducting materials in power generations and industry, and fuel cells for distributed,

environment-friendly power generation.

POWER TRANSMISSION & DISTRIBUTION

In the T&D sector, BHEL is both a leading equipment-manufacturer and a system-

integrator. BHEL-manufactured T&D products have a proven track record in India and

abroad.

In the area of T&D systems, BHEL provides turnkey solutions to utilities. Substations and shunt

compensation installations set up by BHEL are in operation all over the country. EHV level

series compensation schemes have been installed in KSEB, MSEB, SMPSEB and POWERGRID

networks. Complete HVDC systems can be delivered by BHEL. The technology for state-of-the-

art Flexible AC Transmission Systems (FACTS) is being developed.


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TRANSPORTATION

In the transportation filed, product range covers: AC locomotives, AC/DC dual-voltage

locomotives, diesel-electric shunting locomotives, traction motors and transformers, traction

elections and controls for AC, DC and dual voltage EMUs, diesel-electric multiple units, diesel

power car and diesel electric locomotives, battery-powered vehicles.

A high percentage of the trains operated by Indian Railways are equipped with traction

equipment and controls manufactured and supplied by BHEL.

TURBINE AND AUXILIARY BLOCK-III

1.0 GENERAL

1.1 Block-III manufactures Steam Turbines, Hydro Turbines, Gas Turbines and Turbines

Blades. Special Toolings for all products are also manufactured in the Tool Room located

in the same block. Equipment layout plan is a per Drawing appended in Section III.

Details of facilities are given in Section II.

1.2 The Block consists of four Bays, namely, Bay-I and II of size 36x378 metres and 36x400

metres respectively and Bay-III and IV of size 24x402 metres and 24x381 metres

respectively. The Block is equipped with the facilities of EOT Cranes, compressed air,

Steam, Overspeed Balancing Tunnel, indicating stands for steam turbine, rotors, one Test

stand for testing 210 MW steam turbines Russian Design, one Test Stand for Hydro

Turbine Guide Apparatus and two separate Test Stands for the testing of Governing

Assemblies of Steam and Hydro Turbines.

1.3 All the parts are conserved, painted and packed before dispatch.


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2.0 MANUFACTURING FACILITIES2.1 HYDRO TURBINES

Formanufacturing of Hydro Turbines, Bay-I has the following sections:

(a) Circular Components Machining Section This section is equipped with a

number of large/ heavy size Horizontal and Vertical Boring Machines, Drilling

Machines, Centre Lathes, Marking Table and Assembly Bed. The major components

machined in this section are Spiral Casing with Stay Ring, Spherical and Disc Valve

bodies and Rotors.

(b) Runner and Servo Motor Housing Machining Section This section is

equipped with NC/CNC and conventional machines comprising Heavy and Medium size

vertical and Horizontal Boring Machines, Centre Lathes, Grinding machines and Drilling

Machines, Marking Table, Assembly Bed, Assembly Stands for Steam Turbine and Gas

Turbine assemblies and Wooden Platform for overturning heavy components. Hydro

Turbine Runners Servomotors, cylinders, Labyrinth Ring, Regulating Ring, Stay Ring,

Turbine Cover, Lower Ring, Kaplan Turbine Runner Body and Blades are machined

here.

(c) Guide Vanes and Shaft Machining Section This section is equipped with

Heavy duty Lathe machines upto 16 metres bed, CNC turning machines, Horizontal

Boring Machine, Heavy planer, Deep Drilling Machine, Boring Machines, marking

Table, Marking Machines and Assembly Beds. Turbine shafts, Guide Vanes, Journals

and Rotors of Spherical and Disc Valves are machined here. Rotors of Steam Turbines

are also machined in this section.

(d) Assembly Section In this section, assembly and testing of Guide Apparatus, Disc

Valve, Spherical Valves, Servo motor shaft and combined Boring of coupling holes are


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done.

(e) Preservation and Packing Section Final preservation and packing of all the

Hydro Turbine components / assemblies is done here.

(f) Small components Machining Section This is equipped with Planetary Grinding

Machine, Cylindrical Grinding Machines, small size Lathes, Planers, Vertical and

Horizontal Boring Machines. Small components like Bushes, Levers, Flanges etc. and

Governing assemblies and machines here.

(g) Governing Elements Assembly and Test Stand Section This section is

equipped with facilities like oil Pumping Unit, Pressure Receiver, Servomotors etc. for

assembly and Testing of Governing Elements.

2.2 STEAM TURBINES

The facilities and parts manufactured in the various sections of Steam Turbine manufacture are

as follows:

(a) Turbine casing Machining Section It is equipped with large size Planer, Drilling,

Horizontal Boring, Vertical Boring, CNC Horizontal and Vertical Boring machines etc.

Fabrication work like casings, Pedestals etc. are received from Fabrication Block-II.

(b) Rotor Machining Section It is equipped with large size machining tools like

Turning Lathe, CNC Lathes, Horizontal Boring Machines, special purpose Fir tree

Groove Milling Machine etc. Some rotor forgings are imported from Russia and

Germany and some are indigenously manufactured at CFFP, BHEL, Hardwar.

(c) Rotor Assembly Section This is equipped with Indicating Stand, Small size

Grinding, Milling, Drilling, machines, Press and other devices for fitting Rotors andDiscs. Machined Rotor, Discs and Blades are assembled here. Balancing and over

speeding of Rotor is done on the dynamic balancing machine.

(d) Turbine casing Assembly Section Machined casings are assembled and

hydraulically tested by Reciprocating Pumps at two times the operating pressure.


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Introduction to manual lathe

A lathe is a machine tool which rotates the workpiece on its axis to perform various operations

such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the

workpiece to create an object which has symmetry about an axis of rotation. It depend on hard

wired logic.

Lathes are used in woodturning, metalworking, metal spinning, and glass working. Lathes can be

used to shape pottery, the best-known design being the potter's wheel. Most suitably equipped

metalworking lathes can also be used to produce most solids of revolution, plane surfaces and

screw threads or helices. Ornamental lathes can produce three-dimensional solids of incredible

complexity. The material can be held in place by either one or two centers, at least one of which

can be moved horizontally to accommodate varying material lengths. Other work holding

methods include clamping the work about the axis of rotation using a chuck or collet, or to a

faceplate, using clamps.

Operations of lathe

Turning:

This is most basic and important lathe operation. It can be said that, Turning is the

operation which has brought lathe into existence. Job is held at chuck and rotates at

particular RPM. Tool held at tool post. With carriage assembly tool is fed into job

parallel to axis of rotation of job. This operation is used to make job circular and to

reduce the diameter of the job as per need.


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Taper Turning:

This is similar to turning. Apart from turning, tool path cuts the axis of rotation of tool at a

particular angle. This motion of tool is achieved through combined motions of carriage assembly

and cross slide.

Facing Operation

Facing is the process of removing metal from the end of a workpiece to produce a flat surface.

Most often, the workpiece is cylindrical, but using a 4-jaw chuck you can face rectangular or

odd-shaped work to form cubes and other non-cylindrical shapes.

When a lathe cutting tool removes metal it applies considerable tangential (i.e. lateral or

sideways) force to the workpiece. To safely perform a facing operation the end of the workpiece

must be positioned close to the jaws of the chuck. The workpiece should not extend more than 2-

3 times its diameter from the chuck jaws unless a steady rest is used to support the free end.

Knurling

Knurling is not a cutting operation. Knurling is achieved using knurling tool. This tool has two

wheels with slashed lines on it. This tool is pressed against rotating job to get knurled part.

Knurling is achieved using plastic deformation of job material.

Drilling

Drilling at the lathe machine is achieved in bit different way than other lathe operations. Drillingtool is held in the tail stock and fed into job using handle on tailstock.


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Threading

For threading operations to be done accurately, tool must be fed into job with constant

speed. This constant motion is achieved by attaching carriage assembly with lead screw.

Lead screw is connected to the driving mechanism through gear trains. So, for particularrpm of job there is constant rpm of lead screw. Threading is of two types viz. External

Threading, Internal Threading.

a.External ThreadingExternal threading is done by V shaped tool. It is easier than internal threading.

b. Internal Threading

Internal threading is also done by V shaped tool. But in this case tool is mounted on thin

bar which can be able to go into bore of the workpiece where threading is to be done.

Shaping tool for this operation is work of skilled worker.

ChamferingChamfering is slash cutting of the edges of the workpiece. It can be called as very small

taper turning but still taper turning needs a lot more accuracy and skill than chamfering.

Also, both have very different sets of uses.

Grooving

Grooving is generally needed to be done before external threading. In this, grooving tool

is fed perpendicular to axis of rotation of job.

Parting

Parting is like that of grooving. Parting is done for cutting of job into part.


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Disadvantage of hard wired logic

There are too many wiring work in the control panel.

Modification can be quite difficult.

Troubleshooting can be quite troublesome as you reauire a skillful person.

Power consumption can be quite high as coils consume power.

Machine downtime is usually long when problem occur, as it take the long time to

troubleshoot the problem.

INTRODUCTION OF CNC

Development of computer numerically controlled (CNC) machines is an outstanding contribution

to the manufacturing industries. It has made possible the automation of the machining process

with flexibility to handle small to medium batch of quantities in part production.

Initially, the CNC technology was applied on basic metal cutting machine like lathes, milling

machines, etc. Later, to increase the flexibility of the machines in handling a variety of

components and to finish them in a single setup on the same machine, CNC machines capable of

performing multiple operations were developed. To start with, this concept was applied to

develop a CNC machining centre for machining prismatic components combining operations like


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milling, drilling, boring and taping. Further, the concept of multi-operations was also extended

for machining cylindrical components, which led to the development of turning centers.

ADVANTAGE OF CNC MACHINES

Higher flexibility Increased productivity Consistent quality Reduced scrap rate Reliable operation Reduced non productive time Reduced manpower Shorter cycle time High accuracy Reduced lead time Just in time (JIT) manufacture Automatic material handling Lesser floor space Increased operation safety Machining of advanced material

CNC SYSTEMS

INTRODUCTION

Numerical control (NC) is a method employed for controlling the motions of a machine tool

slide and its auxiliary functions with input in the form of numerical data. A computer numerical

control (CNC) is a microprocessor-based system to store and process the data for the control of

slide motions and auxiliary functions of the machine tools. The CNC system is the heart and

brain of a CNC machine which enables the operation of various machine members such as slides,spindles, etc. as per the sequence programmed into it, depending on the machining operations.

The main advantage of a CNC system lies in the fact that the skills of the operator hitherto

required in the operation of a conventional machine is removed and the part production is made

automatic.


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The CNC systems are constructed with a NC unit integrated with a programmable logic

controller (PLC) and some times with an additional external PLC (non-integrated). The NC

controls the spindle movement and the speeds and feeds in machining. It calculates the traversing

path of the axes as defined by the inputs. The PLC controls the peripheral actuating elements of

the machine such as solenoids, relay coils, etc. Working together, the NC and PLC enable the

machine tool to operate automatically. Positioning and part accuracy depend on the CNC

system's computer control algorithms, the system resolution and the basic mechanical machine

accuracy. Control algorithm may cause errors while computing, which will reflect during

contouring, but they are very negligible. Though this does not cause point to point positioning

error, but when mechanical machine inaccuracy are present, it will result in poorer part accuracy.

This chapter gives an overview of the configuration of the CNC system, interfacing and

introduction to PLC programming.

CONFIGURATION OF THE CNC SYSTEM

CNC system SpindleServoServo

EncodeCommand

valueP

LC

N

C

Lead

ScrewTacho

GeneratorWork

pieceVelocity

Feedback

Tape Reader

Tape Punch

Other Devices

Position

Feedback

Proximityswitches

Limit switches Relay coils Pressure

InputsMachine

ElementsOutpu


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Central Processing Unit (CPU)

The CPU is the heart and brain of a CNC system. It accepts the information stored in the

memory as part program. This data is decoded and transformed into specific position control and

velocity control signals. It also oversees the movement of the control axis or spindle whenever

this does not match the programmed values, a corrective action is taken.

All the compensations required for machine accuracy (like lead screw pitch error, tool wear out,

backlash, etc.) are calculated by the CPU depending upon the corresponding inputs made

available to the system. The same will be taken care of during the generation of control signals

for the axis movement. Also, some safety checks are built into the system through this unit and

the CPU unit will provide continuous necessary corrective actions. Whenever the situation goes

beyond control of the CPU, it takes the final action of shutting down the system in turn the

machine.

Speed Control Unit

This unit acts in unison with the CPU for the movement of the machine axes. The CPU sends the

control signals generated for the movement of the axis to the servo control unit and the servo

control unit convert these signals into the suitable digital or analog signal to be fed to the

machine tool axis movement. This also checks whether machine tool axis movement is at thesame speed as directed by the CPU. In case any safety conditions related to the axis are overruled

during movement or otherwise they are reported to the CPU for corrective action.

Servo-Control Unit

The decoded position and velocity control signals, generated by the CPU for the axis movement

forms the input to the servo-control unit. This unit in turn generates suitable signals as command

values. The servo-drive unit converts the command values, which are interfaced with the axis

and the spindle motors

The servo-control unit receives the position feedback signals for actual movement of the

machine tool axes from the feedback devices (like linear scales, rotary encoders, resolves, etc.).

The velocity feedback is generally obtained through tacho generators. The feedback signals are


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passed on to the CPU for further processing. Thus the servo-control unit performs the data

communication between the machine tool and the CPU.

As explained earlier, the actual movements of the slides on the machine tool is achieved

through servo drives. The amount of movement and the rate of movement are controlled by the

CNC system depending upon the type of feedback system used, i.e. closed-loop or open-loop

system

Closed-loop System

The closed-loop system is characterized by the presence of feedback. In this system, the CNC

system send out commands for movement and the result is continuously monitored by the system

through various feedback devices. There are generally two types of feedback to a CNC system --

position feedback and velocity feedback.

DIFERENT CNC MACHINES USED AT BHEL FOR MILLING,

TURNING, FACING, BORING, DRILLING AND OTHER

MANUFACTURING TECHNIQUES OF THEIR PRODUTS.

1) CNC MILLING MACHINES

Item Description : CNC Horz. Milling M/c (6 Nos.)

Model : BFH-15

Supplier : BATLIBOI, INDIA

CNC Control System : SINUMERIK 810 M

Table : 1500 x 400 mm

Traverse : X=1170 mm

Y=420 mm

Z=420 mm


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Spindle Speed : 45 to 2000 RPM

Power Rating : 11 KW

Max. Load Capacity : 630 Kg

Weight of the m/c : 4200 Kg

2) CNC HORIZONTAL BORERS:

Item Description : CNC Horz. Borer

Model : RAPID 6C

Supplier : WOTN, GERMANY

CNC Control System : FANUC 12M

Spindle Dia. : 200mm

Table : 4000 x 4000 mm

Max. Load on Table : 100 T

Travers : X=20000, Y=5000, X=1400mm

Ram traverse : W = 1000 mm

Swing Over Bed : 2400 mm

Spindle Speed : 0125 RPM


Weight of the Job : 110 TON

Weight of the m/c : 124 TON

3) CNC SURFACE BROACHING M/C

Make : Marbaix Lapointe, UK


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Model : Champion 32 /10, 300

CNC System : SINUMERIC 850 M

Broaching capacity (pulling force) : 320 KN

Broaching slide stroke : 10.3 mm

Broaching slide width : 1500 mm

Max tool length (continuous /row) : 9650 mm

Broaching Speed (cutting stroke) : 1-25 M/min

Broaching Speed (return stroke) : 60 M/min

Drive power rating : 135 KW

4) CNC VERTICAL BORERS

Item Description : CNC Vertical Borer

Model : TMD40 / 50

Supplier : OSAKA MACHINES, JAPAN

CNC Control System : FANUC 6TB, 3TC

Table dia : 4000 mm

Turning dia : 5000 mm

Turning Height : 4200 mm

Spindle Speed : 0.23-30 RPM

No. of Ram : 2


Max. Load Capacity : 70T

Machine Weight : 100 T

Max. Ram Travel (Vertical) : 2200 mm


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5) CNC LATHES

Items Description : CNC Centre Lathe

Model : D-1800 NYF

Supplier : HOESCH MFD, GERMANY

CNC Control System : SINUMERIK 3T

Centre Distance : 8000 mm

Swing Over Carriage : 1800 mm

Swing Over Bed : 2400 mm

Spindle Speed : 0125 RPM


Programmable Logic Controller (PLC)

A PLC matches the NC to the machine. PLCs were basically introduced as replacement for hard

wired relay control panels. They were developed to be reprogrammed without hardware changes

when requirements were altered and thus are reusable. PLCs are now available with incresed

functions, more memory and large input/output capabilities.

In the CPU, all the decisions are made relative to controlling a machine or a process. The CPU

receives input data, performs logical decisions based upon stored programs and drives the

outputs. Connections to a computer for hierarchical control are done via the CPU.

The I/O structure of the PLCs is one of their major strengths. The inputs can be push buttons,

limit switches, relay contacts, analog sensor, selector switches, proximity switches, float

switches, etc. The outputs can be motor starters, solenoid valves, position valves, relay coils,

indicator lights, LED displays, etc.

The field devices are typically selected, supplied and installed by the machine tool builder or the

end user. The voltage level of the field devices thus normally determines the type of I/O. So,

power to actuate these devices must also be supplied external to the PLC. The PLC power supply

is designated and rated only to operate the


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internal portions of the I/O structures, and not the field devices. A wide variety of voltages,

current capacities and types of I/O modules are available.


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I/O Devices

Input Devices

PROXIMITY SWITCH--A proximity switch is a sensor that can detect objects withoutmaking physical contact.

In order to effectively sense such objects, the switch must be in close proximity to the object.

PUSH BUTTON--A manual control device that opens or closes a circuit when pressed.Pushbuttons can be normally open or normally closed.

KEY OPERATED SWITCH-- A key switch is a switch that can be activated only by

a key.

Key switches are usually used in situations where access needs to be restricted to the switch's

functions.

FLOW SWITCH--A type of switch that detects the movement of air or liquid in a ductor pipe. The flow switch symbol has a flag or paddle shape that represents either an air flow

switch or a liquid flow switch.

FLOAT SWITCH-- A type of switch that controls the action of a pump as it relates to the

level of liquid in a tank. The float switch symbol has a circle connected to a line that represents a

ball float

PRESSURE SWITCH-- A type of switch that senses the pressure in a pneumatic or

hydraulic system. The pressure switch symbol has a semi-circle connected to a line that

represents the diaphragm.


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SELECTOR SWITCH-- A type of switch that can be turned to different positions to

make a connection with the contacts in that particular position.

LATCHING SWITCH-- A latching switch is a switch that maintains its state after being

activated. A push-to-make, push-to-break switch would therefore be a latching switch - each

time you actuate it, whichever state the switch is left in will persist until the switch is actuated

again.

NON LATCHING SWITCH-- A non-latching switch returns to the original state after

being pressed

Output Devices

RELAY-- A relay is an electrically operated switch. Many relays use an electromagnet to

operate a switching mechanism mechanically, but other operating principles are also used.

Relays are used where it is necessary to control a circuit by a low-power signal (with complete

electrical isolation between control and controlled circuits), or where several circuits must be

controlled by one signal.

CONTACTOR-- A contactor is an electrically controlled switch used for switching

a power circuit, similar to a relay except with higher current ratings.A contactor is controlled by

a circuit which has a much lower power level than the switched circuit.

SOLENOID-- A solenoidis a coil wound into a tightly packed helix. In physics, the term

solenoid refers to a long, thin loop of wire, often wrapped around a metallic core, which

produces a magnetic field when an electric current is passed through it. Solenoids are important

because they can create controlled magnetic fields and can be used as electromagnets.


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PLC Programming

The principle of operation of a PLC is determined essentially by the PLC program memory,

processor, inputs and outputs.

The program that determines PLC operation is stored in the internal PLC program memory. The

PLC operates cyclically, i.e. when a complete program has been scanned, it starts again at the

beginning of the program. At the beginning of each cycle, the processor examines the signal

status at all inputs as well as the external timers and counters and are stored in a process image

input (PII). During subsequent program scanning, the processor the accesses this process image.

To execute the program, the processor fetches one statement after another from the

programming memory and executes it. The results are constantly stored in the process image

output (PIO) during the cycle. At the end of a scanning cycle, i.e. program completion, the

processor transfers the contents of the process image output to the output modules and to the

external timers and counters. The processor then begins a new program scan.

STEP 5 programming language is used for writing user programs for SIMATIC S5

programmable controllers. The program can be written and entered into the programmable

controller as in:

Statement list (STL), Fig.A (a) Control system flowchart (CSF), Fig.A (b) Ladder diagram (LAD), Fig.A (c)

(a)

Statement list

STL

A I 2.3A I 4.1O I 3.2

A I 2.3

AN

D

OR

I 2.3

I 4.1

I 3.2 Q 1.6

Statement

(b) Control system

flow chart CSF

(c) Ladder diagram

I 2.3 I 4.1


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A I 2.3I 2.

3

OperandOperatio

Paramet

I 3.2

Projeect Report

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Transcript of Projeect Report