WIA Weldmatic Synchro Pulse Owner's manual

MANUFACTURED BY WELDING INDUSTRIES

OF

AUSTRALIA PTY

LTD

NORTH

AMERICAN

/

CANADIAN DISTRIBUTOR:

CRC-EVANS AUTOMATIC WELDING

11601

North

Houston

-

Rosslyn

Road

Houston,

Texas

77086

Phone:

999

8920

Telex:

230

240714

CRC AWUR

WELDMATIC SYNCHRO-PULSE CDT

MODEL

NO.

CP34

(CP34-2

6OHz.

Multi

Voltage)

CAT.

12/87

THE INFORMATION CONTAINED

IN

THE FOLDER

IS

SET OUT TO

ENABLE

YOU

TO

PROPERLY MAINTAIN YOUR NEW EQUIPMENT AND ENSURE THAT

YOU

OBTAIN

MAXIMUM

OPERATING EFFICIENCY.

PLEASE

ENSURE

THAT

THIS FOLDER

IS

KEPT

IN

A

SAFE

PLACE

FOR

READY

REFERENCE

WHEN

REQUIRED.

WHEN REQUESTING SPARE PARTS, QUOTE THE MODEL

NO.

AND SERIAL NO.

OF

THE MACHINE AND PART NO.

OF

THE ITEM REQUIRED.

FAILURE

TO SUPPLY

THIS INFORMATION WILL RESULT

IN

UNNECESSARY DELAYS

IN

SUPPLYING THE

CORRECT PARTS.

-SAFETY-

Before

thls equipment

is

put

into

operation,

the

SAFETY PRACTICES

section

at

the

back

of

the Manual

MUST BE READ

COMPLETELY.

This

will

help

avoid

possible

injury

due

to

misuse

or

improper

welding

applications.

[

CONTENTS

I

1.

SPECIFICATIONS

1.1

Technical

1.2

Standard Package

1.3

Optional Accessories

1.4

Welding

schedules

2.

RECEIVING

3.

INSTALLATION

3.1

Machine Location

3.2

Connection to Electr

Mains

Supply

Page

2

Page

3

Page

3

ical

3.3

Cable

&

Hosk

Connections

4.

CONTROLS Page

7

5.

WELDING SET-UP Page

9

5.

I

Electrode Wire and

Shielding

Gas

5.2 Work Lead

5.3

Welding Current

Presetting Guide

5.4

Normal Welding Sequence

6.

GENERAL MAINTENANCE Page

12

6.1

Dust

6.2

Wire-feed

7.

TROUBLE

SHOOTING

Page

12

7.1

Unsatisfactory Welding

Cond

i

t

ions

7.2

No

Welding Current

7.3

Uncontrolled Welding

Current

8.

PRINCIPLE

OF

OPERATION

Page

16

8.1

Pulsed-arc Metal Transfer

8.2

High-Current Switch

8.3

Control Circuits

9.

PRINTED CIRCUIT BOARDS Page

20

9.1

Main Control

Board

9.2

Diagnostic

LED

Indicators

9.3

Diagnostic Test

Points

9.4

Wire-feeder Control

board

CP34-85

10.

SERVICE

INFORMATION

Page

27

10.1

Dis-assembly of the

Rectifler/Switch Unit

10.2

Parts list, CDT Power

Source

10.3

Parts

List,

10.4

Parts

List,

Bernard

E2

Gun

10.5

Parts List,

Rectifier/Switch

Assembly

Two Roll Drive Assembly

11.

PUSH-PULL OPTION

Page

37

11.1

Fitting

Instructions

for

Pull

Type

Welding

Gun

11.2

Parts

Lists

and

Assembl

y

Drawings

12.

SAFETY

PRACTICES

Fig.

1

2

3

4

5

6

7

8

9

IO

11

12

13

14

15

16

17

18

19

20

U

I,

m

n

U

H

Y

L(

U

H

U

H

n

Supply and Voltage Selection Terminals

Welding

Transformer

Voltage

Selection

Cable and

Hose

Connections

Power

Source

Controls

Arc

Sensing

Connections

Welding

Current

and Droplet Transfer

High Current Switch

Typical

Welding Current Waveform

Block Diagram

-

Control Circuits

Main

Control

Board

Overlay

Wire Feeder Control Board Overlay

Circuit

Diagram

CDT

Power-Source Assembly

Rectifier/Switch Assembly

Bernard

E2

400

Amp Gun Assembly

Two

Roll

Drive Assembly

Drive

Roll and

Wire

Guide Table

Hulftegger/WIA

Pull

Gun

&

Cable

Assembly

Hulftegger

Gun

Exploded View

Bernard/Hulftegger Torch Neck

Assembly

Page

43

SYNCHRO-PULSE

CDT

MANUAL

PAGE

2

J,

1

TECHNICAL

-

Output

:

40-350

Amps

k

-

Duty Cycle

:

350

Amps,

100%

-

Open

circuit

voltage

:

70

volts

-

Weight

:

530

lbs

-

Wire

Speed Range

:

40-630

Ingheslmin

-

Insulation

:

Class

'H'

-

225

F

rise

at

104'F

ambient

-

Enclosure

:

Drip-proof

(*

or

as

programmed)

1.2

STANDARD

PACKAGE

-

CP34

Synchro-Pulse

CDT

Welding Power Source

-

W21-5

Wire

Feeder

-

CP34-36

Remote

Control Pendant

-

AM167

Accessory

Lead

Kit

-

Bernard

Gun

Cable Assembly

-

K2

Gas

Regulator

&

Flow

Meter

-

K4

Argon

Gas

Elbow

1,3

OPTIONAL

ACCESSORIES

-

AM166

Push-pull

Gun

Cable

Assembly

and

Control

-

AM117

Mobile

Kit:

-

AM167-0/9

Thirty

Foot

Accessory Lead

Kit

I.

4

WELDING

SCHEDUM

Information

given

for

EPROM

#l0500

Schedule

Electrode

pre

-gas

ramp

(aec)

(sec)

A-

1

Mild

Steel

.035

"

.3

A-

2

Mild

Steel

045"

.3

A-

3

316

Stainless

.035"

.3

A-4

316

Stainless

.045"

.3

A-5

5356

Aluminium

.045"

.3

A-6

5356

Aluminium

,062"

.3 -3

B-

1

Si

1

icon Bronze

,030"

*3

.3

B-

2

Silicon Bronze

.035"

.3

B-

3

Mild

Steel

.05

2

"

.3

B-4

LINDE-95

,045

"

.3

R-5

316

Stainless

,030"

.3

B-6

5356

Aluminium

.035"

.3

fill

.6

0

.6

0

burnback

(sec)

.072

,072

.072

.07

2

.072

,072

.072

,072

.07

2

p05t-ga5

"

0.6

By

fitting

a

replacement

EPROM,

other weld schedules

and

other

selections of timed periods

are

available.

SYNCHRO-PULSE

CDT

MANUAL

PAGE

3

In

general

it

is

a

good practice to move the equipment to the

site

of installation before uncrating.

Use

care in uncrating

in

order

to avoid

damage.

Check the equipment received against the shipping invoice to make

sure the shipment

is

complete and undamaged.

If

any damage has occurred in transit immediately notify CRC Evans

Automatic Welding

or

their authorized agent.

For

all

requested information related

to

this equipment

give

the

correct Model

Identification

and Serial

Number. This

is

1ocated.on

a

name plate attached

to

the right-hand

lower front

of

the machine.

3.

INSTALLATION

3.1

MACHINE LOCATION

Where posslble, in

choosing

a

site

for any welding power-source,

consideration should

be given

to

the

following points:-

-

Availability

of

electrical and shielding

gas

supplies.

-

Accessibility for

the

replacement

of

consumables,

i.e.

weldlng

wire

and

gas

bottles,

and

for

any

future

maintenance

requirements.

-

The

power-source

must

be

positioned

so

that

the

free

flow

of

cool

iny

alr’.

through

the

machlt-le

is

not

Impeded,

such

as;

by

placing

the

rear

of

the

machine

too

close

to

a

wall.

-

Protection

from

wind and driven

rain

-

Breezes blowing through

an

open

doorway

can

result

in

degradation

of

the

weld

shielding

gas

coverage, which can cause weld porosity.

If

such a site

is

unavoidable, consider.ation should

be

given to the

use

of portable

welding screens of a suitable material, The outflow

of

cooling

air

from the welding power-source can

also

cause

similar

problems, and

the

machlne should

be

positioned with this in mind.

-

Airborne dust particles

will

always accumulate

in

vented

equipment, particularly that

wlth

forced

air

coollng and

excessive

buildup can often

be

the cause

of

premature machine failure.

At

all

times

endeavour

to

position the machine to

minimize

the

intake

of contaminated air, particularly that containing metal1

ic

particles

such

as

from

grinding

operations.

(See

also

the

GENERAL

MAINTENANCE section

of

this

Manual.)

3.2

CONNECTION

TO

ELECTRICAL MAINS

POWER

SUPPLY

All

electrical

work

shall

only

be

undertaken

by

a

qualified

electrician.

-CAUTION-

I

Ensure that the Power-source

is

disconnected

from

the Electrical

Malns before undertaking this procedure.

I

SYNCHRO-PULSE

CDT

MANUAL

PAGE

4

SUITABLE

MAINS

VOLTAGES

The Synchro-Pulse

CDT

is

designed

for

connection

to

a

3

Phase

60Hz

Electrical Mains

power

supply.

The

chart below lists the suitable

electrical mains voltages (phase

to

phase) and

the

appropriate

current demand.

NOTE:

It

is

mandatory that the correct Electrical Mains voltage taps

be selected before the equipment

is

operated.

Failure

to

do

so

may

void

warranty.

MAINS

VOLTAGE

I

CURRENT

DEMAND

PER

PHASE

240

460

480

510

575

44A

23A

22A

21A

18A

Access to the machine supply terminals and the combined welding

transformer and control transformer voltage selector

is

gained

by

removing the Power-source side panel adjacent to the front

panel meters. The location

of

each point

is

indicated below,.

FIGURE

1.

SUPPLY

AND

VOLTAGE SELECTION TERMINALS

When

making

connection to the Machine Supply terminals, ensure that

local

codes

are

adhered to, and that the

EARTH

connection

is

secure

1

y

made.

A

cable anchor

for

flexible

power

cables

is

supplied

with the machine.

WELDING

AND

CONTROL

TRANSFORMER

VOLTAGE

SELECTION

The

Welding and Control Transformer voltage

selection taps are

combined in one unit,

as

illustrated

in

figure

2

(following).

Install the links

(total

of

six)

in the manner shown in the figure.

NOTE:

In

this diagram, links

are

connected

for

575V.

STAR/DELTA CONNECTION

For

the mains voltages applicable

to

this

model

CDT,

DELTA

connection

is

required

for

240V

mains supply only,

For

all other supply

voltages

(460,

480,

510,

575)

use

STAR

(WYE)

connection.

SYNCHRO-PULSE

CDT

MANUAL

PAGE

5

VOLT#

IOHL

WELDIN0

TAANaFORMER

CONTROL

YRAN8.

240V

0

00

000

460v

0

00

000

480V

0

00

000

5lOV

0

00

Q0

000

ITAR

OELTA

CONNECTION6

DELTA

460

240

480

610

675

FIGURE

2.

WELDING

AND

CONTROL TRANSFORMER VOLTAGE SELECTION TAPS

3.3

CABLE

AND

HOSE

CONNECTIONS

All

welding

current, control

and

shielding

as

connections

are

shown

in

figure

3,

page

6.

The

complete

set

of

necessary

cables

and

hoses

are

contained in

the

standard

accessory

kit

AM167.

SHIELDING

GAS

HOSES:

The

accessory

kit contains two

gas

hoses.

The

shorter

length

Is

used

to

join

the

output

of

the

shielding

gas

regulator

/

flowmeter to the

gas

nipple on the

rear

panel

of

the Power-source.

The

second hose

is

used to make the

gas

connection

from

the power source front

panel

to the

rear

of

the

W21

wire

feeder.

CONTROL

CABLES:

Engage the remote control

and

the wire feeder control

cable plugs

into

their

respectively

marked

sockets

on

the

power

source

front

panel.

The

control cable connections

for

the wire feeder

are

shown

in figure

3.

Where

a

‘Hulftegger’ pull gun

is

to

be

used,

the

wire feeder

will

be

fitted

with

a

‘Cannon’

socket

and

a

gas

outlet,

via

which

the

necessary connections

to

the

welding gun

are

made.

For

field installation refer

to

chapter

11.

The

wiring associated with this socket is

shown

in

dashed lines

in

the

diagram.

r

SYNCHRO-PULSE CDT

MANUAL

PAGE

6

WELDING

CURRENT CABLES:

Pulsed arc

G.M.A.

welding

is

conducted

with

the electrode

polarity positive, and

the

workpiece negative.

The

positive output

of

the

power

source

is

connected

to

the

welding

gun

via

an adapter mounted with the wire drive

mechanism. Ensure that both

the

positive welding cable

AND

the

voltage

sensing wire

are

securely bolted to

this

adapter.

The

negative output

of

the

power

source

.is

connected

to

the

welding

cable

incorporating the

work

clamp. Both

leads

are

secured

at

the

power

source

by

inserting the

plug into

its

appropriate socket

and

rotating clockwise

to

1 ock

e

GAS

REGULHOR

REMOTE

CONTROL

t

+TO

GUN

CABLE

CONTROL

CABLE

CANNON

EP8

PLUG

9

CORE

FLEX

W21

WIRE

FEEDER

TO

FULb

GUN

Green

-

--

Whfte-<Gun Switch)

-

Red

Red-

(Motor)

Green/Yellow--- White-(Gun Switch)

-

Red/Black Black-(Motor)

White Grey-(Arc

Volts

Sense)

i

GUN

SWITCH)

Blue-

-

Blue

c

-

--

-

7

Brown

-

--

Brown-

- -

-

(MOTOR

1

B1 ue /White (Spare

)

CANNON

XLP

PLUG

3

CORE

FLEX

PEMOTE

CONTROL

2

Bluelx-/”’””rrent’ Brown

l“

3

Gree

ltArc

Length’

(both

1K

ohms)

FIGURE

3.

CABLE

AND

HOSE

CONNECTIONS

SYNCHRO-PULSE

CDT

MANUAL

PAGE

7

4.

CONTROLS

GROUP

CURRENT

CONTROL ARC

LENGYH

COMROL

-

REMOTE PENDANT

FIGURE

4.

CDT

WELDING

POWER

SOURCE

CONTROLS

POWER

OFF/ON:

Use

to

energise

or

de-energise

the

Power-source

and

wire feeder.

POWER

ON

INDICATOR:

Tbis

is

illuminated

when

the Power-source is energised,

indicating

that

the

power

control

circuits

are

activated.

FUSES

:

Upper

3

Amp

.slow-blow

type

3AG

-

Protects the

contactor

circuit.

Lower

-

10

Amp

standard action

type

3AG

-

Protects

the

wire

feeder

circuit.

SYNCHRQ-PULSE CDT

MANUAL

PAGE

8

INCII/PURGE SWITCH:

This

is

a

dual function switch, moving down operates the gas

solenoid valve and provides the

gas

PURGE

function.

This

function

enables

the

gas

lines to be purged

with

the selected shielding gas

and permits the

gas

flow

rate

to

be

adjusted

to

its

correct

operating condition, e.g.

20

to

30

cflhour.

Moving the

inch

purge switch up operates the wire

feed

motor,

feeding the wire into the gun cable system. The wire feed speed

during

INCH

is

determined

by

the setting on

the

current control

pendant.

PROGRAMME

SWITCH:

This

switch

must

be

set

according

to

the welding consumable

in

use.

The standard Synchro-Pulse CDT

is

supplied with

a

weld programme set

comprising

12

individual schedules

as

detailed

on

page

2.

Other

schedules are available from the manufacturer.

GROUP

SWITCH:

The

12

weld schedules referred to above are

accessed

in

two

groups

(A

and

B>

each of

six

schedules. The group switch is used to select

the desired group

of

schedules.

AMMETER:

The

Ammeter indicates the welding current (amp5

average).

VOLTMETER

:

The

Voltmeter

indicates

the

welding

voltage (volts

average).

CONTROL PENDANT:

Consisting

of

a

metal

box

and a flexible cord connected to the

Power

Source, this unit provides:-

Current control

Arc

length control.

‘CURRENT’

CONTROL

-

is

obtained via

a

10

turn vernier control.

This

one

control adjusts

all

the welding parameters

together,

eg.

wire-feed rate,

arc

voltage, pulse frequency and background

current.

‘ARC

LENGTH’

CONTROL

-

is

achieved by turning the potentiometer from

its

mid-point position. Turning towards

‘i”

increases arc

length and towards

‘-’

decreases

arc

length.

NOTE: The

most

ideal welding conditions

are

achieved when

the

arc

length

is

adjusted

to

be

a5

short

as

practicable whilst maintaining

a

stable spray mode

of

welding

arc.

(An occasional short

circuit

associated

with

a

crackle

sound

is

acceptable.)

Changes in weld preparation and/or

work

piece temperature

may

require

adjustment

of

the

arc

length in order to maintain the above

conditions.

SYNCHRO-PULSE

CDT

MANUAL

PAGE

9

5.

WELDING

SET-UP

5.1

ELECTRODE WIRE/SHIELDING

GAS

Select the desired consumable electrode wire and

fit

to

the wire

feeder. Ensure that the wire feeder

is

fitted with the

correct

drive rollers

-

see

page

36.

Connect

to

the

gas

regulator/flowmeter

a

supply

of

shielding

gas

appropriate

to

the welding consumable.

See

list below.

RECOMMENDED SHIELDING

GAS

MIXTURES

M

I

LD

STEEL

High Purity

Argon

t

5%

C02

STAINLESS

STEEL

High

Purity Argon

t

5%

C02

ALUMINIUM

Argon

S

I

LT

CON BRONZE

Argon

-i-

0.5%

Oxygen

LINDE

95

High Purity Argon

t

5%

CO2

Select the appropriate Synchro-Pulse

CDT

schedule.

Use

only the

correct Combination

of

consumable

/

shielding

gas

/

schedule.

Incorrect combinations

will

produce

unsatisfactory welding results.

Set

the

gas

flow

rate

to

suit

the

welding procedure. This

is

usually

in

the

range

of

20

to

30

cf/hour,

however

particularly

for

high

current welding of aluminium,

increased

flow

rates

may

he

required.

NOTE:-

Excessive

gas

flow

is

costly

and

may

adversely

affect

the

welding

conditions.

5.2

WORK

LEAD

Firmly

fix

the ‘work clamp’ to

the

work piece,

as

close

as

possible

to

the welding

zone.

Ideal welding conditions

will

only

be

achieved

if

all

connections are properly secured.

It

is

preferable

wherever possible to weld towards the

work

clamp,

SYNCHRO-PULSE

CDT

MANUAL

PAGE

10

5.3

AVERAGE WELDING CURRENT-PRESETTING GUIDE

The

chart

below

may

be

used

a5

a

guide

in

presetting

the

Synchro-

Pulse

CDT

to

deliver

a

given welding

current.

It

is

presented

as

a

guide

only,

as

the actual welding current can

be

influenced

by

other

factors,

such

as

the

electrode

wire

stickout.

GROUP

A

"Current"

Setting

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

GROUP

B

.035

M/Steel

45

65

85

105

125

145

170

190

210

230

.045

M/Steel

50

85

115

150

185

215

250

285

315

350

"Currentu/

.030

I

.035

Setting

S/Bronze

l

.o

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

35

40

50

55

65

70

80

85

95

100

50

G5

85

100

115

135

150

165

185

200

.035

S/Stee

1

40

55

75

95

110

130

145

.l

6

5

180

200

.045

S/Steel

50

80

110

145

175

205

2

35

270

300

330

60

90

125

155

190

220

255

285

320

350

x

M/Steel

LINDE-95

45

75

100

130

160

185

215

245

270

300

.045

35

60

85

110

130

160

180

205

230

255

30

45

55

70

85

95

110

I25

135

150

70

100

125

155

180

210

2

35

265

290

320

.030

.035

S/Steel

Aluminium

25

35

45

55

65

75

85

95

105

115

SYNCHRO-PULSE

CDT

MANUAL

PAGE

I1

5.4

NORMAL

WELDING

SEQUENCE:

Closing the welding gun switch

will

initiate

the

following sequence

of

events:

-

PRE-WELD

GAS

FLOW.

The

Power Source contactor

is

turned

on,

the

gas

valve

will

open

and shielding gas flows for

a

pr-e-set period.

-

ARC

INITIATION.

At

the

end

of

the

pre-gas

period,

the Power

Source welding output is turned on, and welding voltage is

applied

between the work-piece

and

the electrode wire. Simultaneously,

the

wire

drive motor

will

be started, and

will

begin to

feed

electrode

wire

at

a

slow

rate.

During this phase, the

Power-source

is

set to produce welding

current

pulses

at

a

relatively high frequency to facilitate

arc

initiation.

-

RAMP

UP.

Following the electrode

wire

making contact with the the

work-piece, and the establishment

of

the

arc, the

pulse

frequency

immediately

drops

to a low frequency consistent with the

wire

feed

rate.

As

the

wire

feed

rate

ramps

up

to

the chosen

‘CURRENT’

setting,

so

also does the pulse frequency.

-

CRATER

FILL.

To

end welding, the gun switch

is

released. This

initiates

a

period

of

‘Crater

Fill’

during which the wire-feed

rate

ramps

down

to

a

fixed point over

a

set

period.

-

WELD

END.

At

the completion

of

the

Crater

Fill

period,

the

wire

drive motor

is

dynamically

braked

to

stop.

After

a

short,

pre-set

period, known

as

the

‘hurn-back’

time,

the

Power

Source

welding

output

is

turned

off.

This

period

ensures

that

the

electrode

wire

docs

not

‘freeze’

in

the

weld

pool.

-

POST-WELD

GAS

FLOW.

The gas

valve

will

remain open

for

a

pre-set

time,

providing shielding

gas

to

protect the cooling

weld

pool

from atmospheric contamination. The

contactor

is

turned off.

These

functions

are

represented in the diagram

below:

Gun

Sw

i

tch

Pre

Pos

t

Shielding

Gas

Welding Output

/Burn

Rack

4

Wire

Feed Rate

SYNCHRO-PULSE

CDT

MANUAL

PAGE

12

6.

GENERAL

MAINTENANCE

6.1

DUST

A5

mentioned

elsewhere

in

this Manual, care

should

be

taken to

prevent excessive build-up

of

dust

and

dirt within

the

welding

Power-source.

It

is recommended that at regular intervals,

according to the

prevailing

conditions,

the

machine

covers

be

removed and any dust accumulation be removed by the use of

dry,

low

pressure compressed

air,

or

a

vacuum

cleaner.

Ensure

that the

CDT

Power-source

is

disconnected

from

the

Mains

v01

tage

power

supply

before

any

covers

are

removed.

6.2

WIRE-FEED

A5

with

any

G.M.A.

welding process, in

order

to

obtain

the

most

satisfactory welding results, the wire feed should be smooth

and

constant.

It

is therefore important

to

observe the following

points:

-

Keep

the

gun cable liner clear

of

dust and

swarf

build-up. When

replacement becomes necessary,

fit

only the correct liner

to

suit

the

gun

cable

model,

and

electrode type and

size.

The build-up

of

dust in

a

cable

liner

can

be minimized by regular purging of

the liner with

dry

compressed air.

This

may

be

conveniently

done

each

time

the

wirc spool is

replaced.

-

Replace

the

welding

tip

as

it

becomes

worn

or

damagod.

-

Keep

the

wirc

drive

mechanisn

cI.eat1.

Periodically

check

the

drive

rollers

for

wear

and

for

free

rotation.

-

Check that the electrode wire spool holder rotates smooLhly

and

that

the

braking action is not excessive. This

also

may be

conveniently

done

each

time

the

wire

spool

is

replaced.

r

7.TROUBLE

SHOOTING

To

simplify the fault

procedure,

the following checklists have

been

arranged

under

three

separate headings.

When

fault-finding, refer

to

the

most

appropriate

section.

-

Machine

welds,

but with unsatisfactory

results

Refer

Section

7.1

-

Machine delivers

no

welding current Refer Section

7.2

-

Machine

delivers uncontrolled welding

current Refer Section

7.3

7.1

UNSATISFACTORY

RESULTS

BASIC

CHECKS

-

Check

shielding

gas

and schedule

selected

are

correct

for

the

electrode

wire

in

use;

SYNCHRO-PULSE

CDT

MANUAL

PAGE

13

-

Check for correct gas

flow

rate at the welding torch nozzle and

ensure there

are

no gas leaks,

as

porosity

and

arc

blow-out could

occur.

The

gas nozzle must be free from spatter and firmly attached

to the welding nozzle to ensure that atmosphere is not drawn into

the shielded area;

-

Check

for

good wire feed conditions, ie:

spool

holder brake

not

over-tightened, drive

rollers

not clogged with dust build-up, drive

rollers

the correct size and type to

suit

the welding wire, and the

drive

roll

pressure

is

adequate for consistent feeding. Check

also

that the gun

cable

liner

is

of

correct size and not blocked, and

that the welding tip

is

in

good condition and not excessively worn.

Any

of

the above can cause erratic welding conditions and

ARE

THE

MOST

LIKELY

CAUSES

OF

FAILURE

IN

ALL

GAS

METAL

ARC

WELDING.

They

should therefore be the

first

points checked when problems occur.

-

Ensure

that

the

work clamp

is

securely tightened onto the work-

piece

so

that good electrical contact

is

achieved;

-

Establish that the arc length is correctly set. An arc length

which is too short will

cause

excessive crackle, shorting

and

spatter, while an arc length too long may

result

in weld undercut

and/or

loss

of

arc 'direction';

-

If

the

arc length

is

excessively long and cannot

be

adjusted with

the arc length control,

check

that

the arc voltage

sensing wire

has

not become broken

or

disconnected (see figures

3

and

5).

Poor

wire

feed conditions can also

give

the same symptoms by

not

permitting

the

wire

to

approach

the

arc

at;

the selected speed.

Refar,

again

to

the earlier paragraphs.

-

Work-piece surface contamination

by

water, oil, grease,

galvanizing, paint

or

oxide layers can severely disturb the welding

arc

resulting

in

a

poor weldmet. Should this condition

occur,

surface cleaning

of

the work piece

will

be

necessary;

-

Magnetic arc blow may be encountered particularly when welding

ferrous metals. Magnetic fields which

result

from

the

welding

current being conducted through the work-piece can severely disturb

the welding arc.

This

problem

may

be

overcome by

re-positioning

the

'work'

clamp (welding current return)

so

as to weld towards

it,

welding

towards

a

heavy

tack

weld,

or

in

severe

cases

utilizing

the

'back

stepping' welding technique;

-

Lack

of

one

Mains supply phase can either completely

disable

the

CDT Power Source,

or

merely adversely affect welding conditions.

Have

a

qualified electrician

confirm

that

3

phase

Mains supply

is

available

at

the CDT Power Source, and that the primary voltage

taps

have been correctly selected

for

both the welding and control

transformers;

-

If

the above checks have failed

to

locate the cause

of

unsatisfactory welding conditions,

it

is possible that the

background current circuit

may

have failed.

Loss

of background

current is characterized by

a

weld which appears "dry", coupled with

an inability

to

establish correct operating arc

length.

In

this case, check for background current

with

the following test:

SYNCHRO-PULSE

CDT

MANUAL

PAGE

14

TEST

FOR BACKGROUND

CURRENT

1)

Select

"WIRE INCH" and feed about

40"

of welding wire from the

gun. This will be used

as

a

temporary load on the power source.

2)

With reference

to

figure

10

on

page

21,

remove

fuses

6

and

7

which

will

disable

the

welding pulse.

3)

Set

the "CURRENT" control

on

the remote pendant to

0.0,

disengage

the wire drive mechanism, and select *WIRE INCH".

4)

Close the gun switch with the end

of

the welding wire shorted to

the

work

lead.

5)

The Ammeter fitted to the power source should now indicate

approximately

15

amps.

Increasing the setting

of

the

"CURRENT-

control

should increase the current reading. (The exact minimum and

maximum background current levels are a function of the

weld

schedule in use).

NOTE:

If

"WIRE

INCH'

is

not selected, the background current will

not be adjustable

by

the setting

of

the "CURRENT" control.

6)

If

the above determine that there

is

no background current:

-

Check

LED

15

(refer figure

10).

If

LED

15

is

not

lit, there

has

been

a

failure of the power supply

to

the driver circuit

for

the

background current.

Check

and

replace

if

required, fuse

F5

(1.6

Amp>

and

confirm

15

volts

AC

between

pins

2

and

7

of

plug

P4;

-

Check

the

wiring

Prom

plug

P5

to

the

background

transistor

assembly

(item

2

in figure

14

on

page

30)

for continuity;

-

Replace printed

circuit

board

CP34-105.

7-2

MACHINE

DSIVRRS

NO

WELDING

CURRENT

BASIC

CHECKS

-

Check

that

Mains

Supply

is

available

at

the

CDT

Power

Source,

ie:

fan

running

and

indicator light on;

-

Check continuity

of

the welding current circuit, ie:

work

lead,

work

clamp

and

gun cable connections;

-

If

the

gas

valve

is 'clicking' repeatedly, the Power Source

has

detected a fault in either the shunt connection

or

the switching

assembly

-

see section

7.3

for

procedure.

As

a

safety measure, the

Power Source

will

not operate again until

it

has been turned

off;

-

Inspect the fuses on

the

CDT Power Source

front

panel, replacing

them

if

necessary;

-

Check operation

of

the welding gun switch, ie:

gas

valve

operates

and wire-feed motor

runs

when the gun

switch

is

closed.

If

not,

replace

the

gun

cable

assembly

and

re-test,

SYNCHRO-PULSE

CDT

MANUAL

PAGE

15

INTERNAL

CHECKS

With reference to figure

10

on

page

21,

check the following

diagnostic

LEDs:

-

All

of the following

must

be

lit

whenever the welding power source

is

on

..

.

LEDs

1,

2,

3,

15,

16,

17

and

18.

If

any

of

the

above

are

not

l

it,

check

the related

fuse

and

if

necessary,

AC

supply voltage (refer to section

9.2

on page

20).

NOTE

particularly

LEDs

16,

17

and

18,

also

LEDs

13

and

14:

LED

16

is

the indicator for the

Main

FET

driver

PSU

(ie,

high

current switch-off),

LED

17

is

the indicator for the

SCR

driver

PSU

(ie,

high current swltch-on) and

LED

18

is

the

indicator

for

the

current amplifier

PSU.

LEDs

13

and

14

indicate that the pendant

connection

is

intact.

If

any

of these

are

not

lit,

all

drivers

feeding

the

power semi-conductors in the rectifierlswitch assembly

are

disabled

to

prevent possible damage

to

these components.

-

One

of

the

following

must

be

lft

..

.

LEDs

4,

5,

6,

7,

8

or

9.

If

not, operate the programme

switch

through

all

positions.

If

none

of

the LEDs

are

lit by

this

procedure, check

the

wiring loom and

plug

and socket connection to

the

programme switch.

If

LEDs

are

lit

in

some

but

not

all

switch positions, the programme switch should be

replaced;

-

Check

that

operat

ion

of

the

gun

SW

i

tch

1

ights

LED

12,

and

that

the

INCH/PURGE

switch

lights

LEDs

11/19

when

operated.

7.3

MACHINE

DELIVERS

UNCONTROLLED

WELDING

CURRENT

-

Ensure that this arc voltage sensing

wire

is

correctly

terminated

at

the wire-feeder. Check

for

electrical continuity from the

Gull

Cable

connection

to

the

connector

S1

of

the

Main Control

Board,

(Very

long

arc-length)

CHECK

FOR

CONTINUITY

THESE POINTS\

I

GRAY

TO

INDUCTANCE

URRENT

SHUNT

REDf

TO

WORK

LEAD

-

It

is

now

necessary to establish whether the fault

is

in

the

control

circuitry

or

the

rectifieriswitch assembly:

Unplug the loom from

PCB

plug

P5.

Feed

out

approximately

a

foot

(12")

of

electrode wire from the welding gun. Short the

end

of this

wire

to

the

work-piece

and

close the

gun

switch.

SYNCHRO-PULSE

CDT

MANUAL

PAGE

16

If

no current flows in the welding circuit,

it

is

likely that the

fault lies in the control

of

the rectifieriswitch assembly:

-

Check

that

the wires connecting the current shunt to the

PCB

are

firmly

terminated

with

the

correct

polarity

(sec

figure

51,

and that

the contacting surface5

are

clean;

-

Replace the PCB

CP34-105

and the current shunt.

If

current does flow in the welding circuit, the

fault

lies

in

the

rectifieriswitch assembly. The two possibilities

are:

l.

The

main

SCR

has

failed short circuit;

2.

The

high

current

switch-off

power

mosfets

have failed.

Measure

the resistance

of

the

SCR

(ie, between the two large

heatsinks

in

the

middle

of

the switching assembly).

A

short-circuit

SCR

will

give

a

reading

of

near

0

ohms in both

directions.

Failure

of the high current switch-off

power

Mosfets

may

be

indicated

by

burnt-out resistors

on

the

CP34-11

PCB

or

by

visible

damage

to the individual devices.

Chapter

10

gives directions

for

the replacement

of

these devices.

8.

PRINCIPLE

OF

OPERATION

8.1

PULSED

ARC METAL TRANSFER

The

WIA

Synchro-Pulse

CDT

is

a

Pulsed

Gas

Metal Arc Welder, where

the

metal

transfer

is ideally

in

the

form

of

single droplets

of

electr-ode materiLL1, approximately

the

diameter

of

the

electrode

wire,

transferrcd

with

each

current

pulse.

This

is

achieved

by

the

CDT Power-source supplying

the

arc

with

a

DC

welding current: which

is

not

continuou~,

but;

wtlich

is modulated

between

two

distinct current levels. These are known

as:

1.

the Background current,

and

2.

the

Pulse

current,

as

represented in the figure below

-

L

TIME

”+

FIGURE

6.

WELDING

CURRENT

AND

DROPLET TRANSFER

SYNCHRO-PULSE

CDT

MANUAL

PAGE

17

The Background Current, which

is

normally a small proportion

of

the

peak Pulse Current value, serves mainly to keep the

arc

alight

between pulses.

It

is during the period

of

pulse current that

transfer of the molten weld metal

is

initiated, with ideally the

droplet travelling through the

arc

and arriving

at

the weld

pool

during

the quieter background period.

In

order to maintain

a

constant arc length,

it

is

necessary to

repeat the pulse

at

a

frequency which will Lransfer through the arc,

in

discrete metal droplets, the same metal volume of electrode wire

which

is

being fed into the arc from the wire feeder.

In

general terms,

a

low

wire feed

rate requires

a

low pulse

frequency, and

a

high wire feed rate

a

high pulse frequency.

8.2

HIGH

CURRENT

SWITCH

As

mentioned previously, the output current

of

the

CDT

Power-source

is

made

up

of

a

background current, upon which

is

superimposed high

current pulses. These pulse5 are formed by

a

"high current switch"

which

is

based around

a

large capacity

SCR

(Silicon Controlle$

Rectifier).

A

circuit

of

the switch unit

is

shown below.

The "high current; switch"

is

physically part

of

the Rectifier/Switcb

assembly

as

shown in figure

14,

page

30.

Welding

Arc

L1

SCRl

(PAIN

SWITCH

OFF

1

ON

1

FIGURE

7.

HIGH

CURRENT SWITCH

With reference

to

the diagram, the operation

of

the switch

is

as

follows:

SCRl

is

triggered

'ON'

by the application of

a

signal to its gatel

cathode junction

from

the pulse-on driver. Welding current; then

flows from the rectifier and capacitor bank combination Rl/Cl,

through

the

welding arc, the pulse shaping inductance

LI,

and

SCR1.

To turn SCRl

'OFF',

the transistor bank

S1

is

gated on momentarily

to

reverse

bias

SCRl with the power supply

comprising

R2 and

C2.

The

energy stored in

L1

is

now dissipated

by

causing

a

current

to

flow through

Dl

and the welding

arc.

L

SYNCHRO-PULSE CDT

MANUAL

PAGE

19

8.3

CONTROL

CIRCUITS

The

main

control circuits

of

the

Synchro-Pulse CDT

are

located on

the printed

circuit

board

(PCB)

CP34-105. These circuits respond to

information from the

operator

controls, eg:

the

programme selection

switch and the remote control pendant,

and

also

to current and

voltage feedback signals from

the

welding arc.

The

control

circuits

in turn output

drive

signals to the power

semiconductors which

...

-

Generate the welding Current

Pulses;

-

Control the Background current;

-

Set the Wire-feed rate;

-

Control

the

shielding

gas soleno

id

valve.

l

I

Gun

switch

FIGURE

9.

BLOCK

DIAGRAM

.-

CONTROL

CIRCUITS

SYNCHRO-PULSE

CDT

MANUAL

PAGE

20

19.

PRINTED

CIRCUIT

BOARDS

I

9.1

MAIN

CONTROL

BOARD

CP34-105

The

PCB

CP34-105 incorporates the following circuit

blocks.

-

Regulated power supplies

5V,

t15V

/

-15.36V,

+15V

/

-15V;

-

Unregulated power

supplies:

20V

(3

Off);

-

Constant current

supplies

to remote control pendant:

IOmA

(2

Off);

-

Welding

current

signal

amplifier;

-

Micro-processor

based

control

incorporating

EPROM

data

storage;

-

Output drivers

to

power semiconductors for:

-

Background current (power mosfets);

-

High

current switch-on

(SCR

trigger);

-

High current switch-off (power mosfets).

-

Additional output drivers for:

-

Gas

solenoid

operation;

-

Wire-feed motor run/brake control

command;

-

Analog

output

for

wire-feed

motor

speed control circuit.

A

number

of

test pins and diagnostic

LED

indicators

are

provided

on

this

printed circuit

board.

See

Figure

10

for

the

location

of

these

points,

and

the

following

lists

for

explanation of

the

function

of

each.

9.2

DIAGNOSTIC

LED

INDICATORS

ON-BOARD

POWER

SUPPLIES.

LED

#

15~

AC

P1/3

-

P114

P2<1,6A)

-15.36~

DC

reg.

LED

2

8.5~

AC

P1/6

-

P118

F3(1.6A)

t5v

DC

regulated

LED

1

AC

SUPPLY

ACROSS

PINS

FUSE

#

INDICATOR

FOR

PSU

LED

3

15~

AC

P1/1

-

P113

Fl(1.6A)

+15v

DC

reg.

LED

t5

LED

16

LED

17

LED

18

+20v

DC

Unreg.

(Background)

+20v

DC

Unreg.

~

+20v

DC

Unreg.

l

(Pulse-off)

('Pulse-on)

+15/-15v

DC

reg.

(Shunt

Amp.)

F5<

1.6A)

F6(

1.6A)

F7(

1.6A)

F4(

1.6A)

15~

AC

P412

-

P417

15~

AC

P4/3

-

P4/6

15~

AC

P414

-

P4/5

15~

AC

P4/1

-

P4/8

All

of

the

above

L,EDs

should

be

lit

whenever

the

welding

power

source

is

energ

i

sed.

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WIA Weldmatic Synchro Pulse Owner's manual

WIA Weldmatic Synchro Pulse Owner's manual

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