Electric heating – Metal heating – By arc
Reexamination Certificate
2001-10-10
2003-09-30
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
C219S1370PS
Reexamination Certificate
active
06627850
ABSTRACT:
TECHNICAL FIELD
This invention relates to a consumable electrode type arc welding apparatus.
BACKGROUND ART
In order to carry out a welding operation by a gas shielded arc welding method, a welding apparatus shown in
FIG. 1
has heretofore been used. Referring to the drawing, a reference numeral
1
denotes a base metal,
2
a welding power source,
3
a welding torch,
4
a tip of the welding torch,
5
a welding wire,
6
a welding arc,
11
wire feed rollers,
10
a motor for driving the wire feed rollers,
9
a wire wound spool,
7
an arm to which the welding torch
3
is fixed of a simplified carriage (not shown), or an arm of a welding robot, and
8
a conduit cable for feeding the wire
5
to the welding torch
3
.
In order to carry out a welding operation by such a welding apparatus; first, a suitable voltage is supplied from the welding power source
2
. Consequently, a welding arc
6
occurs between a free end of the welding wire
5
and the base metal
1
, and the welding wire
5
is melted to form a droplet
22
as shown in FIG.
2
. During this time, the welding arc
6
can be generated stably between the base metal
1
and the free end of the welding wire
5
by feeding the welding wire
5
by rotating the wire feed rollers
11
having the motor
10
as a driving power source therefor, by an amount sufficient enough to cause the droplet
22
to be transferred to the base metal
1
.
Thus, in the welding operation which has heretofore been carried out, a feed speed of the welding wire supplied from the tip
4
to a weld zone is set so that the feed speed becomes constant at all times during the welding operation. For example, when a solid wire of 1.2 mm in diameter is used as the welding wire
5
with a welding current supplied at 200~300 ampere and with a carbon dioxide gas as a shielding gas supplied at 25 liters/min., the feed speed of the welding wire
5
is set to a constant level between 5~12 m/min.
On the other hand, the condition observed of the droplet
22
formed at the free end of the welding wire
5
and transferred to the base metal
1
with, for example, a carbon dioxide gas used as a shielding gas is as shown in FIG.
2
. Namely, the droplet
22
starts being formed on a stage shown in
FIG. 2A
, and grows with the lapse of time on stages shown in FIG.
2
B and
FIG. 2C
in order.
As is understood from
FIG. 2
, in a stage in which the droplet
22
starts being formed and grows, the droplet
22
is lifted up by an arc force since the arc occurs on a lower surface of the droplet
22
. Therefore, the droplet
22
cannot be transferred easily to the base metal
1
, i.e., the droplet
22
grows until it turns into the condition shown in FIG.
2
C. The droplet
22
is transferred in an enlarged state to the base metal
1
as if it flew thereto as shown in FIG.
2
D. When the enlarged droplet
22
thus transferred is taken in a molten pool in the base metal
1
, it turns into a molten metal to contribute to the welding but, when the enlarged droplet
22
falls in a position other than the molten pool, it turns into a spatter, which does not contribute to the welding.
Thus, the related art gas shielded arc welding using a carbon dioxide gas as a shielding gas has the following inconveniences.
(1) Since a droplet
22
transferred from the free end of a welding wire
5
to the base metal
1
grows large, the droplet
22
is transferred to a position other than a molten pool to turn into a large-sized spatter in some cases.
(
2
) Since spatters occurring grow large, much time is needed to carry out an operation for removing the spatters deposited on the base metal
1
. Moreover, an efficiency of deposition of droplets from a welding wire
5
to a weld zone lowers to cause a welding efficiency to decrease.
In order to eliminate these inconveniences, the following measures are employed in the methods disclosed in Japanese Patent Laid-Open No. 229682/1996 and Japanese Patent Laid-Open No. 85439/1997.
Japanese Patent Laid-Open No. 229682/1996 proposes welding method and apparatus rarely encountering the occurrence of a spatter, and having a high welding efficiency, which include varying the length of a passage for a welding wire in a welding torch by swinging a wire feed nozzle, which is provided in an inner portion of the welding torch, by an electromagnetic effect; and transferring a droplet, which occurs at a free end of the welding wire, to a base metal in a short-circuiting manner by changing a feed speed of the welding wire, which is sent out from a tip of the welding torch to a weld zone, from a predetermined level to a high level momentarily in a suitable cycle.
Japanese Patent Laid-Open No. 85439/1997 proposes welding method and apparatus rarely encountering the occurrence of spatters, which enable a droplet constituting a primary factor of the occurrence of a spatter to be transferred to a base metal regularly and reliably by varying a welding pule current synchronously with the changing of a feed speed of a welding wire, which is proposed in Japanese Patent Laid-Open No. 229682/1966, from a predetermined level to a high level momentarily in a suitable cycle.
FIG. 3
shows the construction of a welding torch of the apparatus disclosed in Japanese Patent Laid-Open No. 85439/1997. Referring to the drawings, a reference numeral
3
denotes a welding torch,
4
a tip,
5
a welding wire,
8
a conduit cable,
12
a base portion of the torch,
13
a shielding gas supply pipe,
14
a shielding gas injection port,
15
a spring,
16
a wire feeding nozzle,
17
a tip fixing member,
18
A and
18
B magnetic cores,
19
A and
19
B electromagnetic coils,
20
A,
20
B DC voltage generators, and
21
a voltage generator regulating unit.
As shown in
FIG. 3
, in the apparatus disclosed in Japanese Patent Laid-Open No. 85439/1997, the welding torch
3
has a special construction, and the voltage generator regulating unit
21
for swinging the wire feed nozzle
16
, which is provided in an inner portion of the welding torch
3
, by an electromagnetic effect is required. This apparatus was complicated and expensive. Moreover, a feed speed of the welding wire
5
can be varied only in a limited range corresponding to the swinging of the wire feed nozzle
16
in the inner portion of the welding torch
3
.
In the related art welding apparatus, the techniques for suppressing the occurrence of a large sized spatter in a region (not higher than substantially 1.5 m/min) of a low welding speed are attained. However, in a welding operation carried out at a welding speed of not lower than substantially 2 m/min, a welding current is as high as 300A~400A, so that a wire melting speed becomes high to cause a large quantity of droplets to be formed, and an arc to become unstable.
DISCLOSURE OF INVENTION
The present invention has been made in view of the above-mentioned circumstances, and provides simple and inexpensive welding method and apparatus adapted to extremely reduce spatters occurring and scattering even during a welding operation carried out at a speed of not lower than substantially 2 m/min.
According to an aspect of the present invention, the consumable electrode type arc welding method has the steps of feeding a welding wire to a material to be welded, and carrying out a welding operation by generating an arc between the material to be welded and welding wire, the method including the steps, which are used during a welding operation, of reducing after the short-circuiting of the welding wire and material to be welded a wire feeding speed to a low level not higher than that of a wire feeding speed in a regular welding operation, and increasing the wire feeding speed to a level not lower than that of the wire feeding speed in a regular welding operation.
According to another aspect of the present invention, the consumable electrode type arc welding method has the step of carrying out a welding operation by using a consumable electrode type arc welding apparatus provided with a welding power source for canceling short-circuiting when short-circuiting occurs, by raising a
Hirayama Takahide
Koga Yasuhiro
Mita Tsuneo
Nakashima Haruki
Nio Satoru
Jordan and Hamburg LLP
Kabushiki Kaisha Yaskawa Denki
Shaw Clifford C.
LandOfFree
Consumable electrode type arc welding method and device... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Consumable electrode type arc welding method and device..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Consumable electrode type arc welding method and device... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3109587