GB2055491A - Automatic regulation of arc welding - Google Patents
Automatic regulation of arc welding Download PDFInfo
- Publication number
- GB2055491A GB2055491A GB7927282A GB7927282A GB2055491A GB 2055491 A GB2055491 A GB 2055491A GB 7927282 A GB7927282 A GB 7927282A GB 7927282 A GB7927282 A GB 7927282A GB 2055491 A GB2055491 A GB 2055491A
- Authority
- GB
- United Kingdom
- Prior art keywords
- welding
- voltage
- arc
- plant
- output voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/0061—Underwater arc welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Arc Welding Control (AREA)
Abstract
With underwater arc welding, long leads separating the arc from the welding plant produce a voltage drop, which on a constant voltage supply interferes with the arc voltage regulation. This regulation is restored by keeping the output voltage of the plant equal to the sum of a preset voltage and another voltage, proportional to the short circuit current. Upon starting (contactor 6 closed), circuit 9 memorises the short- circuit current as measured by saturable reactor 8 and adds this to the preset value. The welding plant is then supplied via contactor 5, rather than 6 and choke 7, and the regulation begins. <IMAGE>
Description
SPECIFICATION
Equipment for underwater arc welding
The invention refers to equipment for
underwater arc welding and welding in similar
conditions where the power source is installed a
considerable distance away from the welding arc,
e.g. at sea level, with the welding operator
working at the bottom of the sea, at a
considerable depth. When welding with
consumable electrodes in a shielding gas, the so
called MIG process, the power source is usually
expected to supply to the arc a constant voltage which together with an electrode fed into the arc
at a constant rate of feed results in stable arc
conditions.
My British patent specification 1540880
describes a method to overcome the difficulties
relating from the fact, that the voltage drop along
the cables may result in the requirement of a rising
output voltage of the power source in contrast to
the constant voltage required at the arc. According
to my patent specification pilot leads from the arc
to the power source permit the output voltage of
the plant being controlled by comparing the arc
voltage with the preset voltage of a potentiometer
installed in the power source.
Object of the invention is an equipment which
permits the described operation without the need
of pilot leads. On underwater arc welding
equipment according to the invention means are
provided for controlling the output voltage of the
welding plant so that it remains equal to the sum
of two voltages, one of these being preset on a
potentiometer at the plant, and the other a voltage
proportional to the current and determined by the
short circuit current at a measured voltage, as well
as means for changing the control of the output
voltage from said measured voltage to said sum of
two voltages.
An example of the invention is shown in the
drawing. The welding arc 1 to be operated at the
bottom of the sea, receives its supply over long
cables 2 from the welding plant 3 stationed above
sea level and connected to the mains 4 over a
contactor 5. Another contactor 6 connects the
welding plant 3 to the mains 4 over a choke 7.
Before starting the welding operation the welding
plane is connected to its supply over the choke 6,
with the aim to reduce the voltage at the point of
operation to a safe value. The current flowing
through the cable is sensed over the D.C. current
transformed 8, designed as a D.C. saturated
reactor. When the operator touches the workpiece
earth, the current through the cables as well as the
voltage are sensed and stored in the computing
circuit 9. After this storage has been completed
the computing circuit gives a signal to the
contactor 5 which then connects the plant
through the mains, it reconnects the control of the
output voltage, and it also starts operating the electrode feed not shown in the drawing.The control circuitry is preferably designed so that the values of voltage and current taken at the initial short circuit are recorded without delay, whereas the controlled output voltage on the plant during welding will receive its signal with a delay so as to avoid hunting of the controls.
A circuit similar to that shown in the drawing can be used where the welding plant is connected to the welding arc immediately at or near its full value i.e. without preliminary series connection of a choke. In that case the short circuit current will be measured and compared with the output voltage of the plant when the arc is struck and the signal for the start of the electrode feed is given.
For an operation described it will be preferable to use a welding equipment described in my British patent specification 947814 where the short circuit current is limited to a defined value by giving the plant a nearly rectangular characteristic.
It is known to compensate the voltage drop in power cables by compounding the supply voltage.
An application of such known methods for the control of welding plant has to account for the special conditions imposed by the characteristics of the arc. The invention makes use of the fact, that the arc produced with a consumable electrode is as a rule preceded by a short circuit current, either for striking the arc itself or for closing a pilot circuit connecting the power source. In both cases the output voltage feeding the welding cables will be equal or very nearly equal to the voltage drop along these cables.
1. An equipment for underwater arc welding over long welding leads with consumable electrodes supplied at a constant rate of feed, with means for controlling the output voltage of the welding plant so that it remains equal to the sum of two voltages, one of these being preset on a potentiometer at the plant, and the other a voltage proportional to the current and determined by the short circuit current at a measured voltage, as well as means for changing the control of the output voltage from said measured voltage to said sum of two voltages.
2. An equipment according to claim 1, where the output voltage is reduced until the operator produces a short circuit, with means for measuring the output voltage and short circuit current.
3. An equipment according to claim 1, incorporating a welding plant with constant or rising output voltage characteristic in the arc voltage range and static limitation of the short circuit current beyond that range.
4. An equipment according to claim 1 to 3, with fast response to the current and voltage signals under short circuit conditions, and delayed response afterwards.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (4)
1. An equipment for underwater arc welding over long welding leads with consumable electrodes supplied at a constant rate of feed, with means for controlling the output voltage of the welding plant so that it remains equal to the sum of two voltages, one of these being preset on a potentiometer at the plant, and the other a voltage proportional to the current and determined by the short circuit current at a measured voltage, as well as means for changing the control of the output voltage from said measured voltage to said sum of two voltages.
2. An equipment according to claim 1, where the output voltage is reduced until the operator produces a short circuit, with means for measuring the output voltage and short circuit current.
3. An equipment according to claim 1, incorporating a welding plant with constant or rising output voltage characteristic in the arc voltage range and static limitation of the short circuit current beyond that range.
4. An equipment according to claim 1 to 3, with fast response to the current and voltage signals under short circuit conditions, and delayed response afterwards.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7927282A GB2055491B (en) | 1979-08-06 | 1979-08-06 | Automatic regulation of arc welding |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7927282A GB2055491B (en) | 1979-08-06 | 1979-08-06 | Automatic regulation of arc welding |
Publications (2)
Publication Number | Publication Date |
---|---|
GB2055491A true GB2055491A (en) | 1981-03-04 |
GB2055491B GB2055491B (en) | 1983-04-27 |
Family
ID=10507009
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB7927282A Expired GB2055491B (en) | 1979-08-06 | 1979-08-06 | Automatic regulation of arc welding |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2055491B (en) |
-
1979
- 1979-08-06 GB GB7927282A patent/GB2055491B/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
GB2055491B (en) | 1983-04-27 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |