smk project

7/30/2019 Smk Project

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PROJECT TITLE

MILLING MACHINE

CONTROL WITHAC DIGITAL SERVO DRIVE

SYSTEM



Name Reg No

MEGANATHAN. C - 5050910057

MOHAMMED HUSSAIN .M - 5050910059

MURALI KRISHNAN. S - 5050910061

MURUGANANDAM. D - 5050910063

Under the guidance of

Mr. C.SUBRAMANI M.E (Ph.d) (Asst. Professor, School of Electrical Engineering)



1. Project Objective

2. Introduction

3. Analysis of hydraulic & AC Digital Servo system

4. AC Digital Servo Drive System

5. Result

6. Conclusion

7. Reference

Overall View:



1.Project Objective

2. Introduction



5. Result

6. Conclusion

7. Reference



1. PROJECT OBJECTIVE:

To improve the following parameters of

existing milling machine by changing the

table movement control from Hydraulic to

AC DIGITAL SERVO DRIVE SYSTEM, to

Increase the availability

Reduce rejections Reduce power consumption




2.Introduction



5. Result

6. Conclusion

7. Reference



2.INTRODUCTION

- About the company

• Brakes India Ltd, a TVS Group company is a

leading automobile brake manufacturer in

India

•

Customers include Multi national companieslike Toyota, Nissan, Maruthi Suzuki,

Volkswagen, Daimler and Indian giants like

Tatas, Ashok Leyland, Mahindra & Mahindra



2.INTRODUCTION

- About the project•

The Milling machine has hydraulic system for controlling the tablemovement. Problems faced with hydraulics:

- Less reliability and repeatability

- More time taken for setting-up of machine

- Components scrapped during setting

- Needs skilled man power for setting and breakdown attending

- High power consumption

- Running of multiple parts not possible

• These problems are planned to beeliminated/ reduced by controlling

the table movement with

AC Digital Servo Drive system



2.INTRODUCTION

- Working of a Brake System

Our Project is onCaliper Disc Brake



2.INTRODUCTION

- Reason for Project Selection

• The caliper brake has housing and carrier• The carrier is mounted on the knuckle

• During braking, the entire vehicle inertia comes on the carrier• The dimension of carrier is highly critical

• Hence, this project is selected

Housing

Carrier

Brake Disc




2. Introduction

3.Comparison of hydraulic & Electrical Servo

systems


5. Result

6. Conclusion

7. Reference



3. COMPARISON of HYDRAULIC and

ELECTRICAL SERVO

- What is a Servo?



Motor – Hydraulic/

Electric

Position

feedback


ELECTRICAL SERVO

- Example of a Servo

Power sourcePosition

Input




ELECTRICAL SERVO

- Merits and DemeritsNo HYDRAULIC SERVO ELECTRIC SERVO

1 Positioning accuracy depends on

hydraulic oil viscosity, temperature

etc.

Accuracy is independent of the

environment. With closed loop control,

micro millimeter accuracy is possible

2 Changing the table position takes time Can be done by the touch of a button

3 Needs skilled man power for setting

and trouble shooting

Since control is through buttons and

alarm messages, can be operated easily.

4 Suitable for manufacturing one part

number in large volumes.

With easy positioning, can be used for

manufacturing multiple part nos.

5 High power consumption due to

continuous running of Hydraulicmotor

Servo motor gets power only when the

table movement is required. Hence lowpower consumption.

6 Constraints in hydraulic pressure

restricts the cutting parameters.

Hence less output and low

productivity.

Suitable for very high cutting parameters.

So productivity can be increased by many

times.

7 Low cost Cost is comparitively high




2. Introduction

3. Comparison of hydraulic & Electrical Servo

systems

4.AC Digital Servo Drive System

5. Result

6. Conclusion

7. Reference



4. AC DIGITAL SERVO DRIVE SYSTEM

- AC Servo System Concept

AC DigitalServo Drive

System

Servo Motor, Servo Drive and Encoder are

the important parts of an AC Servo System

Encoder

Servo

Motor

Servo

Drive




- Block Diagram

2

1

3

1. AC Servo Motor2. AC Digital Servo Drive3. Position Sensor

Servo Drive System




- Drive types




- Classification of Servo Motors

• AC Servo motor is AC synchronous motor, with 3phase winding in Stator and rare earth permanent

magnets in Rotor. It is generally called as AC SERVOmotor




- Comparison of Servo Motors

S.

noParameter DC Servo Motor AC Servo Motor Stepping motor

1 Capacity Less than 2 kW 100W to 10 kW Less than 100 W

2 Advantages

Smaller outside

dimensions.

Large Torque

Good Operationefficiency

Good controllability

Low cost

High Speed

High Torque

Good Operationefficiency

No maintenance

Compact

High output Cheap

3 Disadvantages

Out of step and magnet

noise at low speed

operations

Maintenanceintensive due to

brushes

Costlier, compared to

other models.

Out of step at low

speeds

Magnet noise at low

speeds

• AC Servo motor is more suitable for High Speed, Highresponse, faster acceleration and deceleration controls.

•

Since no brushes, no maintenance is required.




- Construction of AC Servo motor

Overallconstruction

• Very simple design, life determined by bearing life, nobrushes and winding in rotor.

•

Working principle same as AC Synchronous motor.




- Operation of AC Servo motor

• Vector Control or field oriented control

• Permanent magnetic field is shown as N-S• Field oriented control generates three phase statorcurrents in such a way that the resultant current vector Ir

is always perpendicular to the magnetic field vector B

Vector Diagram




- Working of AC Servo Drive

• AC input is converted and inverted, and fed to the motor.

• The control Circuit monitors the Voltage, current etc and

also has the “Lock-out” circuit to introduce delay in firingto compensate for the delay in OFF time of the IGBTs.

PWM Inverter

Control circuit

Input AC DC

Bus

Output Voltage

from PWM

Inverter




- Types of Feedback devices

Resolver Encoder




- Comparison of feedback devices

S.no Item Photo Type Encoder Magnetic type encoder Resolver

1 Features

Simple processing circuit

Durable against noise,

since Digital Signal

High resolution

Not suitable for hightemperature application

Simple processing circuit

Durable against noise

Strong against shock and

vibration

Not suitable for hightemperature application

Complex processing

circuit

Rugged

Strong against noise and

vibration

Available for high temp.

application

2Speed

Detection

By Frequency to Voltage

conversion

Usable as Digital data

By Frequency to Voltage

conversion

Usable as Digital data

Uses phase variation of

voltage as speed data

3Position

Detection

Uses incremental pulse

Easy to apply Zero

position pulse

Uses incremental pulse

Easy to apply Zero position

pulse

Needs processing

circuitry for getting

incremental data

• Photo type encoder is selected for our system, due toits High resolution




- Working of Photo Encoder

• Fall and raise of A&B are counted for position, speed anddirection

•

Marker pulse C is used for arriving at initial position

Encoder Schematic Pulses A,B and Marker Pulse - C




- System working

2

1

3

• AC Power flows from Drive to the motor

• Motor speed and position detected by Encoder and feedbackfirst given to drive. Based on the error value, the amplitude ofthe power signal varies

• Position feedback given to other controls for checking theposition and stopping the motor

Position

Input




- Schematic

Before - Hydraulic system

After – AC Servo Drive system



Adjust hyd.cylinderposition

Adjustcylinder

travel speed

Job checking

•Check the dimensionby trial & error

• If not ok repeat theabove process

AFTER –

AC SERVO DRIVE SYSTEM

BEFORE - HYDRAULIC SYSTEM

Hydraulic Cylinder

Hydraulic Valve


- Steps in changing part no

http://localhost/var/www/apps/conversion/releases/20121107221618/tmp/scratch_3/proj%20video.avi




2. Introduction


systems


5.Result

6. Conclusion

7. Reference



5. RESULT

- MTTR & MTBF

MTTR – Mean Time To Repair :- It is the average time required to repair a failed device- It reduced from 7 hours to 0.5 hours

MTBF – Mean Time Between Failures:- It is the time elapsed between two failures

- It increased from 100 hours to 350 hours

0

1

2

3

4

5

6

7

8

9

A v e r a g e R e p a i r t i m e i n H o u r s

Month

Mean Time To Repair

MT…

AC

Servo

System

Replaced

0

50

100

150

200

250

300

350

400

A v e r a g e R e p a i r t i m e i n H o u r s

Month

Mean Time Between Failures

M…

AC

Servo

System

Replaced



5. RESULT

- Cycle time per component

Cycle time:- It is the total time from beginning to the end of the

milling operation.- Lower cycle time will improve productivity and give

more no of components for the same time frame.

-Cycle time reduced from 60 secs to 30 secs due to:* Faster speed of servo motor, Higher rigidity during milling

Before - with Hydraulic systemS No Operation 1 2 3 4 5 6 7 8 9 10 11 1 2 1 3 14 15 16 17 18 19 20 2 1 22 2 3 2 4 2 5 2 6 2 7 2 8 2 9 30 3 1 32 3 3 3 4 3 5 3 6 3 7 3 8 3 9 40 4 1 42 4 3 4 4 4 5 4 6 4 7 4 8 4 9 50 5 1 52 5 3 5 4 5 5 56 57 5 8 5 9 60

1 Rapid forward

2 Spindle start

3 Feed start - Milling starts

4 Rapid return

5 Spindle stops

Cycle starts ---->

After - AC Digital Servo Drive System

S No Operation 1 2 3 4 5 6 7 8 9 1011 1 2 1 3 14 15 16 17 18 19

202 1 22 2 3 2 4 2 5 2 6 2 7 2 8 2 9

303 1 32 3 3 3 4 3 5 3 6 3 7 3 8 3 9

404 1 42 4 3 4 4 4 5 4 6 4 7 4 8 4 9

505 1 52 5 3 5 4 5 5 56 57 5 8 5 9

60

1 Rapid forward

2 Spindle start

3 Feed start - Milling starts

4 Rapid return

5 Spindle stops

Cycle starts ----> Cycle Ends ---->

Cycle Ends ---->

Operation Time - In seconds



5 RESULT



5. RESULT

- Power Consumption

Hydraulic Power pack • Motor capacity in kW – 5.0

• Running time/day in Hrs – 16

• Power consumed/ day – 60 Units

Servo Motor • Motor capacity in kW – 2.5

• Running time/day in Hrs – 16

• Power consumed/ day – 16 Units

Before After

Power cost saving – Rs 1 lakh per annum – 44 Units/day, Rs 8/ unit for 300 days

5 RESULT



5. RESULT

- Cost saving

Total cost saving working:

Reduction of MTTR: Rs 21,000 1,500

Setting time reduction Rs 12,000 1,500

Rejections Rs 1,500 -

Power consumption Rs 144,000 38,400

Total Rs 178,500 41,400

Net Cost saving Rs 137,100

Productivity increase Rs 200,000Total cost saving Rs 337,100

Cost of AC Digital Servo

Drive SystemRs 600,000

Return on investment 2 years

Before After



5. RESULT

No ParameterUnit of

Measure

Required

Trend

Before – Hydraulic

system

After – with AC

DIGITAL SERVO

DRIVE system

1Reliability – Mean Time To

Repair – MTTR

Time in

Hours7 .0 0.5

2Reliability – Mean time

between failures – MTBF

Time in

Hours100 350

3Repeatability – Process

capability Index - CPkIndex no 0.8 1.67

4 Average Setting time Hours 4.0 0.5

5 Components Rejection Nos 15 0

6 Productivity per shift Nos 480 960

7 Power consumptionkWh/

day60 16

8Need for Skilled man

powerNo - Required Not Required

9 Cost SavingRs in

lakhs-

3.37




2. Introduction


systems


5. Result

6.Conclusion

7. Reference



6. CONCLUSION

• All the project objectives are achieved:

- Availability increased by decreasing MTTR and

improving MTBF

- Rejections reduced to Zero- Power consumption reduced by 44 units/ day

• Cost saving of Rs 3 lakhs per annum achieved, with

return on investment of 2 years




2. Introduction


systems


5. Result

6. Conclusion

7.Reference



7. BIBLIOGRAPHY

1. Basics of Industrial Servo Drives -Marcel Dekker

2. Mechatronic Servo System – Nakamura

3. Servo Motors and Industrial Control Theory – Frederick F Ling

4. Electrical Technology – BL Theraja & AK Theraja

5. Basic Electronics for scientists and Engineers – Dennis Eggleston

6. A text book of Electrical Technology – AC & DC Machines – Theraja

7. Wikipedia

8. AC Servo Motors – Mecapion

9. Servo System Basics - Omron

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