Presentation On Summer Training

Compiled & Presented By Ashutosh Singh 7th Semester B.Tech

B.H.E.L -A Brief Introduction 1st unit- Bhopal in August 1956 B.H.E.L. is the largest engineering and manufacturing

enterprise in India in the energy/infrastructure sector with strong man force of 82000 people. B.H.E.L. manufacture over 180 products under thirty major product groups and caters to core sectors of the Indian Economy viz., Power Generation and Transmission, Industry, Transportation, Telecommunication, Renewable Energy, etc.

Contd… Certification acquired by B.H.E.L are Systems- ISO

9001, Environmental Management Systems-ISO 14001 and Occupational Health and Safety Management Systems-OHSAS 18001 and has also adopted the concepts of Total Quality Management. B.H.E.L. has installed equipment for over 90,000 MW of power generation- for Utilities, Captive, and Industrial users.

MANUFACTURING UNITS OF B.H.E.L.                    

First Generation Units BHOPAL Heavy Electrical Plant HARDWAR Heavy Electrical Equipment Plant HYDERABAD Heavy Electrical Power Equipment Plant TIRUCHY High Pressure Boiler Plant   Second Generation Units JHANSI Transformer and Locomotive Plant HARDIWAR Central Foundry and Forge Plant TIRUCHY Seamless Steel Tube Plant   Unit Through Acquisition and Merger BANGALORE Electronic Division Electro Porcelain Division   New Manufacturing Units RANIPAT Boiler Auxiliaries Plant JAGDISHPUR Insulator Plant RUDRAPUR Component and Fabrication Plant BANGALORE Industrial System Group

Mission, Vision & Values of B.H.E.L VISION:

A world class engineering enterprise committed to enhancing stakeholder value. Mission: To be an Indian Multinational Engineering Enterprise providing total business solution through quality products, system and services in the fields of energy, industry, transportation, infrastructure and other potential areas.

Contd.. VALUES: Zeal to Excel Zest for change. Integrity and fairness in all matters. Respect for dignity and potential of every

individual. Strict adherence to commitments. Ensure speed of response. Faster learning, teamwork and creativity. Loyalty and Pride in the Company.

What Makes B.H.E.L So “Special” The quality and reliability of its products . The emphasis on design, engineering and

manufacturing to international standards . Quality Management Systems- ISO 9001. Environmental Management Systems-ISO 14001 . Occupational Health and Safety Management Systems-OHSAS 18001.

INTRODUCTION OF CNC MACHINE CNC machine tools have been widely accepted as time

proven manufacturing technique all over the globe. Numerical control turns machine tools into a flexible production unit with a multitude of possible application. Modern day computerized numerical control system (CNC) is the result of advancement and sky rocketing microelectronics . Flexibility as inherent feature of minicomputer and microcomputer gave new technology –“Software Oriented System”.

HISTORY OF CNC US Air Force asks MIT to develop a "numerically controlled" machine

(1949). Prototype NC machine demonstrated (punched tape input) (1952). CNC machines (computer used to link directly to controller) (1980). DNC: external computer “drip feeds” control programmer to machine tool controller (1990).

MOTIVATION To manufacture complex curved geometries

in 2D or 3D was extremely expensive by mechanical means (which usually would require complex jigs to control the cutter motions) Machining components with repeatable accuracy Unmanned machining operations

Conventional milling machines

Vertical milling machine

SPECIAL FEATURES OFFERED BY CNC MACHINE Thermal stabilization Axis calibration Lost machine compensation

WORKING PRINCIPLE OF CNC M/C Electronic industries association defines

numerical control as “A system in which action is controlled by direct insertion of numerical data. The system must automatically interpret at least some potion of data.” In NC machine tools the main function is to control the displacement and positioning of slides, spindle, speed, feed rate, selection of tool and many other auxiliary functions.

Contd… The major elements that comprises NC machine tools are :Control system – CNC The machine tool Servo drive units Feedback devices Operator control Electrical cabinet

Contd… Motion control is done by: servo-controlled motors T a b le L e a d s c re w A /C M o to r

E n c o d e r

~

S e r v o C o n tro lle r C o u n te r

C o m p a ra to r

In p u t(c o n v e rte d fr o m a n a lo g to d ig ita lv a lu e )

CNC terminology BLU: basic length unit  smallest programmable move of each axis.

Controller: (Machine Control Unit, MCU)  Electronic and computerized interface between operator and m/c Controller components: 1. Data Processing Unit (DPU) 2. Control-Loops Unit (CLU)

Controller components

Data Processing Unit: Input device [RS-232 port/ Tape Reader/ Punched Tape Reader] Data Reading Circuits and Parity Checking Circuits Decoders to distribute data to the axes controllers.

Control Loops Unit:

Interpolator to supply machine-motion commands between data poin Position control loop hardware for each axis of motion

Types of CNC machines Based on Motion Type: Point-to-Point or

Continuous path

Based on Control Loops: Open loop or

Closed loop

Based on Power Supply: Electric

or

Hydraulic

Based on Positioning System: Incremental or Absolute

or

Pneumati

Open Loop vs. Closed Loop controls

Open loop control of a Point-to-Point NC drilling mach NOTE: this machine uses stepper motor control

Components of Servo-motor controlled CNC Motor

lead screw rotation

Motor speed control

feedback

table moves

position sensed by encoder

Two types of encoder configurations

Motion Control and feedback Encoder outputs: electrical pulses (e.g. 500 pulses per revolution)

Rotation of the motor  linear motion of the table: by the leadscrew

The pitch of the leadscrew: horizontal distance between successive threads

One thread in a screw  single start screw: Dist moved in 1 rev = pitch

Two threads in screw  double start screw: Dist moved in 1 rev = 2* pitch

Manual NC programming Part program: A computer program to specify

- Which tool should be loaded on the machine spindle; - What are the cutting conditions (speed, feed, coolant ON/OFF etc) - The start point and end point of a motion segment - how to move the tool with respect to the machine.

Standard Part programming language: RS 274-D (Gerber, GN-code)

Contd… The RS274-D is a word address format Each line of program == 1 block Each block is composed of several instructions, or (words) Sequence and format of words: N3

G2

sequence no

X+1.4

Y+1.4

Z+1.4

I1.4

J1.4

K1.4

destination coordinates dist to center of circle

preparatory function

F3.2

S4

T4

M2

tool

feed ratespindle speed miscellaneous function

Manual Part Programming Example 5” 2.5” p3

p2

p4

p5

1”

Tool size = 0.25 inch, Feed rate = 6 inch per minute, Cutting speed = 300 rpm, Tool start position: 2.0, 2.0 Programming in inches

5”

45° (4, 4) p1 p0 (2, 2)

Motion of tool: p0  p1  p2  p3  p4  p5  p1  p0

1. Set up the programming parameters 5” 2.5” p3

p2

p4

p5

1”

Programming in inches 5”

Use absolute coordinates Feed in ipm 45°

N010 G70 G90 G94 G97 M04 (4, 4) p1 p0 (2, 2)

Spindle speed in rpm Spindle CCW

2. Set up the machining conditions 5” 2.5” p3

p2

p4

p5

1”

Machine moves in XY-plane Use full-circle interpolation

5”

Feed rate Spindle speed 45°

N020 G17 G75 F6.0 S300 T1001 M08 (4, 4) p1 p0 (2, 2)

Tool no. Flood coolant ON

3. Move tool from p0 to p1 in straight line 5” 2.5” p3

p2 1”

p4

p5

Linear interpolation target coordinates N030 G01 X3.875 Y3.698

5”

45° (4, 4) p1 p0 (2, 2)

4. Cut profile from p1 to p2 5” 2.5” p3

p2

p4

p5

1”

Linear interpolation 5”

target coordinates N040 G01 X3.875 Y9.125 45°

or

(4, 4) p1

N040 G01 Y9.125

p0 (2, 2)

X-coordinate does not change  no need to program it

5. Cut profile from p2 to p3 5” 2.5” p3

p2

p4

p5

Linear interpolation target coordinates

1”

N050 G01 X5.634 Y9.125 5” y = 9 + 0.125 = 9.125 (6.5 - x)2 + 0.1252 = (1 - 0.125)2 x = 5.634

45°

p3

(x, y)

(4, 4) p1

(6.5, 9)

.125

p0 (2, 2) 1”

6. Cut along circle from p3 to p4 5” 2.5” p3

p2

p4

p5

1”

circular interpolation, CCW motion 5”

target coordinates

45° (4, 4) p1 p0 (2, 2)

N060 G03 X7.366 Y9.125 I6.5 J9.0 coordinates of center of circle

7. Cut from p4 to p5 5” 2.5” p3

p2

p4

p5

1”

5”

Linear interpolation 45° (4, 4) p1 p0 (2, 2)

target coordinates (Y is unchanged) N070 G01 X9.302

8. Cut from p5 to p1 5” 2.5” p3

p2

p4

p5

1”

5”

Linear interpolation target coordinates (see step 3) 45°

N080 G01 X3.875 Y3.698 (4, 4) p1 p0 (2, 2)

9. Return to home position, stop program 5” 2.5” p3

p2

p4

p5

1”

Linear interpolation

target coordinates (see step 3)

5”

N090 G01 X2.0 Y2.0 M30 45° (4, 4) p1 p0 (2, 2)

end of data N100 M00 program stop

Automatic Part Programming Software programs can automatic generate CNC data Define Tool

CNC data Make 3D model Simulate cutting

Automatic part programming and DNC Very complex part shapes  very large NC program NC controller memory may not handle HUGE part program

computer feeds few blocks of NC program to controller

When almost all blocks executed, controller requests more blocks

ADVANTAGES OF CNC MACHINES Productivity Flexibility in design and production Inspection Floor space Inventory Material Handling  Tooling Operator’s Skill Scrap and Rework Costing Better Management Information and Control

THANK YOU !! Go Green….