CNC Turning Centre.pptx

7/29/2019 CNC Turning Centre.pptx

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Reference for Viva and practical Exam

CNC Turning Centre


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CYCLESTART

FEEDHOLD

EDIT

AUTO

MDI JOG

HANDLE

ZERORETURNMODE

0%

100%

200%

FEEDRATEOVERRIDE

10%

25% 50%

100%

RAPIDOVERRIDE

1

12

TURRET INDEX2

3

4

5

67

89 10 11

SLOW FAST

EMERGENCYSTOP

FANUC 10TPOWER

ON

OFF

O N G P AX Y Z Q B

I J K R C

F D H L #M S T /EOB

U V W

Sp

E ? @ @,

[ ] ( ) *

PAGE CURSOR

SHIFT

7 8 9

4 5 6

1 2 3- 0+ = CAN

RESET

START

CALC

INPUT

NC/PC

AUX

X00.0000Z00.0000

X Z

X1X10

X100

0

ON

OFFDRYRUN

SINGLEBLOCK

MACHINELOCK

OPTIONALSTOP

BLOCKDELETE

X+

X-

Z-

JOYSTICK

Z+

ON OFF

SPINDLE

ORIGIN

X Z

0%100%

130%

SPINDLE LOAD

0%100%

130%

AXIS LOAD

X Z

OD ID

CLAMPDIRECTION

OFF ON

MEMORYPROTECT

CHUCK TAILSTOCK

Key concept #1

From programmers viewpointFrom operators viewpoint

Key concept #2

In key concept #1 we look at the

machine from a programmers viewpoint

In key concept #2 we look at the

machine from an operators viewpoint


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Machining operations

Rough turning/finish turning

Rough boring/finish boringDrilling

Tapping

Threading

Grooving/neckingKnurling


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Universal slant bed Chucker slant bed Twin spindle horizontal Single spindle vertical

Twin spindle vertical Mill/turn machines Gang type Sliding headstock

There are many forms of CNC turning

centers

In all cases

X will be the diameter controlling axis

Z will be the length controlling axis


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Universal style slant bed turning center

Front view of machine


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Headstock& Spindle



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Work-holding

Device



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Tailstock

BodyQuill

Center



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Turret


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A universal slant bed turning center can perform all

types of turning applications:

Chucker workShaft workBar work

Thats why its called a universal style


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Z Axis- +



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X

Axis

-

+



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X

Axis

-

+


X is the diameter controlling axis


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X

Axis

-

+

3.000

X3.0


X is DIAMETER

If you want to turn a 3.0 inch diameter

X3.0 will be the commanding word


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X

Axis

-

+

3.000

X3.0


X is DIAMETER

Once again:X is always the diameter-controlling axis

Z is always the length controlling axis

Also:

X+: always gets bigger in

diameter

Z+: always away from the

spindleThough some machine tool builders

reverse the polarity of the X axis


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Advantages of CNC

- 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


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NC machines

Motion control is done by: servo-controlled motors

~

Servo Controller

Counter Comparator

EncoderA/C Motor

Input (converted from analog to digital value)

TableLeadscrew


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CNC terminology

BLU: basic length unitsmallest 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)


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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 or Pneumatic

Based on Positioning System

Incremental or Absolute


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Open Loop vs. Closed Loop controls


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Open loop control of a Point-to-Point NC drilling machine

NOTE: this machine uses stepper motor control


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Components of Servo-motor controlled CNC

Motor speed control

Two types of encoder configurations

Motor lead screw rotation table moves

position sensed by encoderfeedback


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Absolute Coordinate System Incremental Coordinate System


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CNC programming

Programming consists of a series of instructions in form of lettercodes

Preparatory Codes:

G codes- Initial machining setup and establishing operating

conditions

N codes- specify program line number to executed by the MCU

Axis Codes: X,Y,Z - Used to specify motion of the slide along X, Y, Zdirection

Feed and Speed Codes: F and S- Specify feed and spindle speed

Tool codes: T specify tool number


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NC | CNC

Numerical control is a system in which the actionsare controlled by the direct insertion of numerical

data at one point and the system must be in a

position to interpret at least a part of this data.

In numerical control the programme is fed to themachine by means of a punch tape and this

punch tape has to be recycled for each product of

that batch. It does't have any memory.

Where as in CNC (computer numerical control),

the machine is usually having an on board control

with memory to store the programme..


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Overview

By integrating a computer processor, computernumerical control, or CNC as it is now known,

allows part machining programs to be edited and

stored in the computer memory as well as

permitting diagnostics and quality control functionsduring the actual machining.

All CNC machining begins with a part program,

which is a sequential instructions or codedcommands that direct the specific machine

functions.

The part program may be manually generated or,

more commonly generated by computer aided part

Documents

CNC Turning Centre.pptx