Electric heating – Metal heating – By arc
Reexamination Certificate
2001-01-30
2003-04-29
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
C219S125100, C901S042000
Reexamination Certificate
active
06555786
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a welding machine of which welding tool, such as a welding torch, is moved by automated equipment such as a robot. More particularly, it relates to a welding machine manipulated by the automated equipment and performing arc welding using a consumable electrode.
BACKGROUND OF THE INVENTION
In arc welding, it is important to move a welding torch maintaining a relative position between a work-piece and the welding torch. Welding by a robot has an advantage of higher speed over welding by holding a torch with a worker's hand (hereinafter referred to as “manual welding”). Reproducibility in repeating operations is also important in welding. Regarding high-speed-welding in particular, which allows little tolerance for disperse of relative positional relation between the work-piece and the welding torch, the manual welding cannot deal with it but a robot welding can do it. As a result, welding machines manipulated by automated equipment expand their application extensively.
A case of gas shielded metal arc welding, which uses a dc power source having a constant voltage characteristic as a welding power source, and also uses a consumable electrode as a welding electrode, is described hereinafter.
A voltage at an electrode is dependent both on an arc voltage and a weld-electrode-resistance, so that an amount of heat given to the welding electrode is controlled by a welding current. Heat generated melts metal, so that supply quantity of depositing metal is determined with respect to the current. In other words, when an arc voltage and a wire extension remain constant, the welding current is determined by a supply quantity of the depositing metal (=welding wire). A voltage supplied to the electrode is referred to as a welding voltage. This welding voltage and the welding current are controlled by a welding controller. The welding manipulated by automated equipment such as a robot has been controlled basically in the same way as the manual welding.
If the heat amount generated is constantly used for melting the depositing metal, uniform welding is always expected. However, there are the following abnormal cases: a work-piece has a gap and the gap is uneven, or a thickness of the material constituting the work-piece varies depending on spots, or a member of greater heat capacity is disposed near a groove and thus the heat is absorbed unevenly. For these cases, an amount of depositing metal supplied should be finely controlled responsive to the heat amount generated depending on spots along a weld line.
FIG. 3
shows a depositing metal feeder. In
FIG. 3
, welding wire
12
wound on spool
11
is pulled out, then fed to a welding torch (not shown) by wire feeder
14
driven by motor
13
. Motor
13
is powered through cable
15
, which also couples motor
13
to a controller (not shown). Cable
15
transmits a control signal, e.g., an armature voltage signal in addition to powering motor
13
. Spool
11
is held by base
17
, and wire feeder
14
as well as driving motor
13
is held by base
18
.
FIG. 6
shows a control system of a conventional depositing metal feeder. Depositing metal feeder
21
, detailed in
FIG. 3
, is controlled its feeding of the depositing metal by feeder controller
22
via cable
15
. Feeder controller
22
follows a signal transmitted via cable
25
from welding controller
24
built in welding power source
23
, and controls feeder
21
. In other words, feeder
21
is controlled by welding controller
24
built in power source
23
. Welding wire
12
is fed to the welding torch (not shown) to be welded. Power cable
16
supplies a welding current and a welding voltage from welding power source
23
to the welding torch. In general, power cable
16
transits wire feeder
14
and is led to the torch by a torch cable (not shown). Welding power source
23
is powered from outside via input cable
26
.
As discussed above, in the conventional control system of the depositing metal, welding power source
23
powers the torch, while welding controller
24
built in power source
23
controls the wire feeding. Therefore, fine control, such as varying the supplying amount of the depositing metal responsive to the heat amount generated depending on spots along the weld line, could not be expected.
SUMMARY OF THE INVENTION
A welding machine is manipulated by automated equipment, where the automated equipment can control a supplying amount of depositing metal while a welding controller controls a welding current and a welding voltage during the welding. A welding machine in an exemplary embodiment of the present invention comprises the following elements:
(a) automated equipment for moving a welding tool relative to a work-piece;
(b) an equipment controller for controlling the automated equipment;
(c) a depositing metal feeder for feeding the depositing metal to a weld point nearby the welding tool; and
(d) a depositing metal feeder controller for controlling the depositing metal feeder.
In the construction discussed above, the equipment controller is coupled to the feeder controller so that a signal related to feeding the depositing metal is transmitted from the equipment controller to the feeder controller.
This structure allows a feeding amount of the depositing metal to be controlled by the information of a fed amount of the depositing metal on the equipment controller side in addition to the information about a welding current and a welding voltage supplied from a welding controller on a welding power source side. Therefore, an optimum welding condition for respective weld points along a weld line is obtainable. As a result, quality welding can be achieved.
REFERENCES:
patent: 2525657 (1950-10-01), Diller
patent: 3267251 (1966-08-01), Anderson
patent: 4163886 (1979-08-01), Omae et la.
patent: 4647753 (1987-03-01), Nakashima et al.
patent: 5148000 (1992-09-01), Tews
patent: 5510596 (1996-04-01), Xu et al.
patent: 5614116 (1997-03-01), Austin et al.
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
Shaw Clifford C.
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