Stt wave shaping principles, Appendix b b-3 – Lincoln Electric IM649 Wave Designer User Manual

Page 57

Advertising
background image

Appendix B

B-3

STT WAVE SHAPING PRINCIPLES

WAVE DESIGNER

27850060

BACKGROUND AMPS

PI

NCH AMPS

PEAK

AMPS

TAILOUT

T

1

T

2

T

3

T

5

T

6

T

7

T

0

FIGURE B-2. WELD DROPLET TRANSFER.

From time T

0

to T

1

:

Background current is a steady-state current level, between 50 and

(Background Current) 100 Amps that maintains an arc to form a weld bead.

From time T

1

to T

2

:

An arc voltage detector indicates that the arc is shorted; background

(Ball Time)

current is reduced for approximately 0.75 milliseconds.

From time T

2

to T

3

:

High current is applied to speed the transfer of molten metal to the

(Pinch)

weld puddle. A dV/dt calculation indicates when fuse separation is
about to occur; current is reduced to 50 Amps.

Time T

4

:

Fuse separation occurs at low current. Time T

4

is a function of

(Fuse Separation)

voltage, and not indicated on the amperage waveform.

From time T

5

to T

6

:

A period of high arc current that melts the electrode back.

(Plasma Boost)

From time T

6

to T

7

:

Arc current is reduced from Peak Amps to the Background current

(Plasma)

level.

Advertising