1. TECHNICAL FIELD
The preset invention relates to an arc welding device and, in particular, to an arc welding robot and a robot system including the arc welding robot.
2. Description of the Related Art
As shown in
Another conventional arc welding device includes a plurality of units each having a welding torch, a torch cable and a wire feeder and only the welding torch of each unit may be exchanged by a not shown tool exchanger. In such a welding device, for example, while the torch cable is connected to the wire feeder in each unit, the welding torch of a unit not in use is held by a holding means and the other welding torch of a unit in use is fixed to the wrist of the robot, whereby the two welding torches may be selectively used as needed.
In the conventional arc welding device, the configuration of peripheral equipment is often complicated, as the multi-electrode torch is fixed to the end of the robot and a plurality of torch cables are arranged. Further, as the multi-electrode torch is generally large, the torch may interfere with peripheral equipment or other structures.
An object of the present invention is to provide an arc welding device having a simple structure so as to resolve the above problems.
In order to resolve the above problems, there is provided an arc welding device comprising: one single-electrode welding torch; a plurality of wire feeders for feeding a welding wire to the welding torch; and a wire feeding path having a plurality of wire inlets for receiving a plurality of welding wires fed from the wire feeders and one wire outlet for feeding one of the welding wires to the welding torch; wherein one welding wire selectively fed from one of the wire feeders is fed to the welding torch for welding, through one of the wire inlets connected to the wire feeder and the wire outlets.
The wire feeding path may be arranged in the welding torch. In this case, the wire inlets are respectively connected to the wire feeders by a plurality of torch cables.
Alternatively, the wire feeding path may be arranged in one torch cable which connects each wire feeder to the welding torch.
According to another aspect of the invention, there is provided an arc welding robot system comprising: the above welding device of the invention; a robot mechanism for holding the welding torch; at least one welding power source for supplying welding current to the welding device; and a control part for controlling the at least one welding power source.
The wire feeders may be mounted on the robot mechanism. Alternatively, at least one of the wire feeders may be located at a place other than on the robot mechanism.
The above and other objects, features and advantages of the present invention will be made more apparent from the following description of the preferred embodiments thereof, with reference to the accompanying drawings, wherein:
a and 1b are front and side views, respectively, of a total configuration of an arc welding robot system according to a first embodiment of the invention;
a and 3b are front and side views, respectively, of a total configuration of an arc welding robot system according to a second embodiment of the invention;
a and 6b are front and side views of a total configuration of an arc welding robot system of the prior art.
Embodiments of the invention will be described with reference to the drawings.
a and 1b show a total configuration of an arc welding device 10 according to the invention. The arc welding device 10 includes a welding torch 12, first and second torch cables 14a and 14b connected to the welding torch 12, and first and second wire feeders 16a and 16b for feeding a welding wire to the welding torch 12 through the first and the torch cables 14a and 14b, respectively. The torch 12 and the wire feeders 16a and 16b are mounted on a robot mechanism 18. The robot mechanism 18 is preferably a type of unit including vertical multi-joint and has a wrist element 182 for holding the torch 12, a forearm 184 having the wrist element 182 at one end thereof for supporting the wire feeders 16a and 16b, an upper arm 186 connected to the other end of the forearm 184 and a turning body 188 for turning the upper arm 186. First and second welding power sources 20a and 20b are connected to the first and second wire feeders 16a and 16b, respectively. The power sources 20a and 20b are activated by a control part 22 configured to send a command to the power sources. In other words, the control part 22 controls the power sources 20a and 20b such that a welding current and a welding voltage, applied to power cables (described below with reference to
The welding torch 12 serves as a single-electrode welding torch. As schematically shown in
Although two welding power sources are used in the embodiment of
Next, the actual welding is described. In the above robot system, when a workpiece is welded, the workpiece is attached to a jig (not shown) arranged in the front of the robot mechanism 18. In accordance with a command from a system control panel 23 commanding the control part 22, the robot mechanism 18 checks the kind of the workpiece and carries out welding with a welding condition suitable for the workpiece. The welding current and voltage, welding speed, wire feeding speed, a kind of assist gas and the material of the welding wire, etc., are predetermined in relation to the kind of workpiece. At this point, a method of the invention for changing the material of the wire corresponding to the kind of workpiece is described below. It is assumed that welding wires 26a and 26b are assigned to workpieces A and B (not shown), respectively. When the robot mechanism 18 is commanded to weld the workpiece A by the system control panel 23, the robot mechanism 18 sends a command to the first power source 20a for feeding the welding wire 26a, as the wire 26a must be used for welding the workpiece A. Then, the first power source 20a sends a feeding command to the first wire feeder 16a for feeding the wire 26a. Although the feeding command may be sent to the first wire feeder 16a via the control cable for wire feeding, the command may also be sent via the output signal switcher. When the welding of the workpiece A is finished, the kind of next workpiece to be welded is outputted from the system control panel 23.
If the next workpiece is also the workpiece A, the next welding may be carried out in the same way as the above. However, when the next workpiece is the workpiece B, the kind of the wire fed to the welding torch 12 is changed before welding, as described below. First, the first power source 20a commands the first wire feeder 16a to retract the wire 26a from the torch 12. At this point, the first wire feeder 16a retracts the wire 26a such that the front end of the wire 26a is positioned before a junction 28d of the wire liner 28. Then, the second power source 20b commands the second wire feeder 16b to feed the wire 26b to the welding torch 12, whereby the second wire feeder 16b feeds the wire 26b such that the front end of the wire 26b extends from the torch 12 or the tip 28c of the liner 28 by a required length. As not shown, each wire feeder may include a feeding roller for feeding the wire, a motor for controlling the rotation of the roller and a feedback device for controlling the motor, whereby the wire may be precisely fed. In addition, when it is difficult to control the length of the wire extending from the tip 28c in the robot system, a wire cutter (not shown) may be arranged near the robot mechanism 18. The wire cutter may be configured to cut the wire when the wire is moved to a predetermined position of the wire cutter by the robot mechanism 18.
When a further next workpiece is the workpiece A, the wire 26b may be retracted such that the front end of the wire is positioned before the junction 28d and the wire 26a may be fed to the torch 12 for welding.
An arc welding device 30 according to a second embodiment of the invention, as shown in
The configuration of the wire liner of the second embodiment is described with reference to
The first and second wire liners and the first and second assist gas tube are connected to a junction part or a junction block 42 arranged in the torch cable 34. The junction block 42 includes a wire liner section 44 having first and second openings 44a and 44b configured to receive the wires extending through the wire liners 38a and 38b, respectively. The junction block 42 further includes a flow path 46 having first and second openings 46a and 46b configured such that the assist gas passing through the gas tubes 40a and 40b may flow into the openings 46a and 46b, respectively. As the wire liner section 44 has a Y-shape, the wire extending through the liner section 44 via the opening 44a or 44b may project from a third opening 44c of the liner section 44. Similarly, as the flow path 46 has a Y-shape or a junction, the assist gas flowing into the opening 46a or 46b may flow out from a third opening 46c of the flow path 46. The wire liners 38a and 38b and the block 42 are preferably detachable from the torch cable 34 so as to allow them to be exchanged when, for example, they are worn by contacting the wire.
As shown in
When it is preferable to change the kind of assist gas in changing the kind of the wire, the change of the assist gas may be carried out by the similar way used for the wire liners 38a and 38b. In other words, a solenoid valve (not shown) is mounted on each wire feeder and is controlled for changing the assist gas. The assist gas supplied to the solenoid valve via a gas pipe or the like flows in the assist gas tube 40a or 40b and the block 42 and, then, reaches the front end of the welding torch 12. If required, pre-flow may be carried out until old assist gas in the flow path is fully replaced with new assist gas. Although the solenoid valve may prevent the assist gas from reversely flowing, to make sure of preventing the reverse flow, a check valve (not shown) may be arranged on the side of the block 42 near the wire feeder. Also, the check valve allows the changing time of the assist gas to be reduced.
In the junction block 42, abraded powder or particles of the wire may deposit. In this case, the powder may be blown to the outside with the assist gas by means of another configuration in which the assist gas may flow into the wire liner section 44 in the block 42. However, in case that the abraded powder is required to be more positively removed or that the assist gas does not flow in the wire liner section as shown in
In the arc welding robot system of the invention, the motion of the torch cable during the welding operation may be stable by using an appropriate constitution, for example, described in Japanese Unexamined Patent Publication (Kokai) No. 2004-223576 or Japanese Patent Application No. 2004-71304 (assigned to the same applicant). In this constitution, a welding torch is rotatable about an axis apart from an axis of revolution of an output flange of a wrist element. Further, the constitution includes a slide mechanism arranged on a forearm of a robot and capable of movably supporting the torch cable, and a tension force generator for moving the slide mechanism away from a work tool. As the Y-shaped or two-way torch cable described above is relatively bulky, the torch cable may interfere with external equipments. However, due to the above constitution, even when the orientation of the welding torch is widely changed, the motion of the torch cable may be small. Therefore, the welding may be carried out without interference between the torch cable and the external equipments. Although the illustrated embodiments of the invention include the two wire feeders and the Y-shaped or two-way wire liner, the embodiments may include three or more wire feeders and a wire liner having three or more ways.
According to the arc welding device of the invention, as plurality kinds of welding wires may be fed to a single-electrode welding torch, one of the welding wires may be selected and used for welding but, nevertheless, the welding torch does not interfere with external equipment.
While the invention has been described with reference to specific embodiments chosen for the purpose of illustration, it should be apparent that numerous modifications could be made thereto, by one skilled in the art, without departing from the basic concept and scope of the invention.
Number | Date | Country | Kind |
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2004-293004 | Oct 2004 | JP | national |