DESCRIPTION

WIRE FEEDING DEVICE

TECHNICAL FIELD

The present invention relates to an arc welding device. Having a startup switch, a wire feeding device, and an arc-welding power source, the arc welding device carries out arc welding by feeding wire and generating arc. In particular, the present invention relates to a wire feeding device having a sequence controller that controls sequence operation of welding start and welding end through the operation of a startup switch.

BACKGROUND ART
An arc welding device generally has a startup switch for giving instructions on welding start and welding end, a wire feeding device for feeding a welding wire, and an arc-welding power source for supplying electric power between a welding wire and a work to be welded.

Through the operation of the startup switch, the arc welding device carries out following two sequence operations: a normal operation and a self-holding operation. According to the sequence operation in the normal operation, when the startup switch is in the on state (for example, a torch switch is remained on), the device performs a sequence operation of welding start. When the startup switch is in the off state (for example, the torch switch is remained off), the device performs a sequence operation of welding end.

According to the sequence operation in the self-holding operation, when the startup switch is in the first-time on state (for example, a torch switch is remained on), the device performs welding under conditions of a beginning stage of the welding. When the startup switch is in the first-time off state (for example, the torch switch is remained off), the device performs welding under conditions of normal welding (steady-stage welding). After that, when the startup switch is in the second-time on state (for example, the torch switch is remained on), the device performs welding under conditions of an ending stage until the startup switch is turned in the second-time off state (for example, the torch switch is remained off).

The self-holding operation is controlled by a sequence control circuit, and such a sequence control circuit has been put into practical use in various forms (for example, see patent literature PTL 1). The sequence control circuit is mounted on an arc-welding power source or on a wire feeding device.

Fig. 3 schematically shows the structure of a conventional arc welding device. The arc welding device has startup switch 1, wire feeding device 18, and arc-welding power source 19. Fig. 3 shows the example in which the sequence control circuit (i.e. first sequence controller 13) is mounted on arc-welding power source 19.

In Fig. 3, the startup switch for giving instructions on welding start and welding end, which is disposed on an arc-welding torch or on a peripheral device (not shown), is connected to wire feeding device 18.
Wire feeding device 18 has electromagnetic valve 2, motor 3, first setup section 5, startup signal input section 9, startup signal output section 10, setup value output section 11, and electromagnetic-valve driving power input section 12. Electromagnetic valve 2 supplies the arc welding site with shielding gas or stops the gas supply. Motor 3 feeds a welding wire (not shown). First setup section 5 determines a first welding-current setup value and a first welding-voltage setup value, which are the welding conditions of normal welding (steady-stage welding). Startup signal input section 9 receives a startup signal from startup switch 1. Startup signal output section 10 outputs the startup signal to arc-welding power source 19. Receiving the setup values determined in first setup section 5, setup value output section 11 outputs them to arc-welding power source 19. Electromagnetic-valve driving power input section 12 receives electric power from electromagnetic valve controller 14 of arc-welding power source 19 so as to drive electromagnetic valve 2.

Arc-welding power source 19 has first sequence controller 13 for sequence control, electromagnetic valve controller 14, wire feeding controller 15, first operation setting section 16, and third setup section 17. Electromagnetic valve controller 14 supplies electric power or stops the power supply to electromagnetic valve 2 of wire feeding device 18 according to signal Vg fed from first sequence controller 13. Similarly, wire feeding controller 15 supplies electric power or stops the power supply to motor 3 of wire feeding device 18 according to signal Vm fed from first sequence controller 13. First operation setting section 16 determines whether first sequence controller 13 performs the self-holding operation or not. Third setup section 17 determines a third welding-current setup value and a third welding-voltage setup value, which are the welding conditions of the beginning-stage welding before the normal welding (steady-stage welding) and the ending-stage welding after the normal welding.

As described above, first operation setting section 16 determines presence or absence of the self-holding operation performed by first sequence controller 13. According to the setup signal from the setup switch, first sequence controller 13 controls the following so as to be suitable for the self-holding operation: welding output; open/close of electromagnetic valve 2; and operation/non-operation of motor 3.

The workings of such structured arc-welding power source, particularly, of wire feeding device 18 will be described.

First, the working described hereinafter is the case where first operation setting section 16 of arc-welding power source 19 determines that first sequence controller 13 performs the self-holding operation.
To start welding, startup switch 1 is turned in the on state (i.e. first-time on). The output signal from startup switch 1 is transmitted to startup signal input section 9 of wire feeding device 18 and then to startup signal output section 10. Further, the output signal from startup switch 1 is transmitted, as a startup signal, to startup signal input section TS3 of first sequence controller 13 of arc-welding power source 19.

Receiving the startup signal, first sequence controller 13 outputs an instruction signal for opening electromagnetic valve 2 to electromagnetic valve controller 14 so as to supply shielding gas.

Electromagnetic valve controller 14 applies DC voltage (electric power) to electromagnetic valve 2 of wire feeding device 18 via electromagnetic-valve driving power input section 12 of wire feeding device 18.

First sequence controller 13 outputs the setup values determined in third setup section 17 to welding output section 20. Receiving the setup values, welding output section 20 supplies welding power to a welding wire (not shown) and a work.

Besides, first sequence controller 13 outputs an instruction signal for starting wire feeding to wire feeding controller 15. Wire feeding controller 15 supplies motor 3 of wire feeding device 18 with electric power to feed the welding wire. Through the procedures above, the welding starts.

The description below is on the case where startup switch 1 is turned off (first-time off), not waiting for arc generation between the welding wire and the work after the start of welding.

In response to turned-off startup switch 1, first sequence controller 13 outputs signal Vm for stopping wire feeding to wire feeding controller 15. Receiving the signal, wire feeding controller 15 stops the power supply to motor 3 of wire feeding controller 18. First sequence controller 13 outputs instruction signal Vo to welding output section 20 so as to stop the supply of welding power to the welding wire and the work. At the same time, first sequence controller 13 outputs signal Vg for closing electromagnetic valve 2 to electromagnetic valve controller 14. Receiving the signal, electromagnetic valve controller 14 stops the DC voltage supply to electromagnetic valve 2 that is provided through electromagnetic-valve driving power input section 12 of wire feeding device 18. Through the procedures above, the feeding of welding wire, welding output, and the shielding gas supply stop, so that the welding is completed.

Next, the description below is on the case where startup switch 1 is turned off (first-time off) after arc generation between the welding wire and the work in the welding.

First sequence controller 13 controls welding output based on the setup values determined in first setup section 5. Upon detecting the turn-on (second-time on) of startup switch 1, first sequence controller 13 controls welding output based on the setup values determined in third setup section 17 until startup switch 1 is turned off again (second-time off).

When startup switch 1 is turned off (second-time off), first sequence controller 13 outputs signal Vm for stopping wire feeding to wire feeding controller 15. Receiving the signal, wire feeding controller 15 stops the power supply to motor 3. First sequence controller 13 stops the supply of welding power to the welding wire and the work. At the same time, first sequence controller 13 outputs signal Vg for closing electromagnetic valve 2 to electromagnetic valve controller 14. Receiving the signal, electromagnetic
valve controller 14 stops the DC voltage supply to electromagnetic valve 2 via electromagnetic-valve driving power input section 12. Through the procedures above, the feeding of welding wire, welding output, and the shielding gas supply stop, so that the welding is completed.

Next, the working described below is the case where first operation setting section 16 of arc-welding power source 19 determines that first sequence controller 13 performs the normal operation.

The output signal from startup switch 1 is transmitted to startup signal input section 9 of wire feeding device 18 and then to startup signal output section 10. Further, the signal is transmitted to first sequence controller 13 of arc-welding power source 19 as a startup signal.

When startup switch 1 is in the on state (for example, a torch switch is remained on), first sequence controller 13 outputs an instruction signal for opening electromagnetic valve 2 to electromagnetic valve controller 14 so as to supply shielding gas. Electromagnetic valve controller 14 applies DC voltage to electromagnetic valve 2 via electromagnetic-valve driving power input section 12. Further, first sequence controller 13 outputs the setup values determined in first setup section 5 as welding conditions to welding output section 20. Receiving the setup values, welding output section 20 supplies the welding wire and the work with welding power. Besides, first sequence controller 13 outputs an instruction signal for starting wire feeding to wire feeding controller 15. Wire feeding controller 15 supplies motor 3 of wire feeding device 18 with electric power to feed the welding wire. Through the procedures above, the welding starts.

The working described below is the case where startup switch 1 is turned off (for example, a torch switch is remained off) after the start of welding in the normal operation. Upon detecting the turned-off of startup switch 1, first sequence controller 13 outputs signal Vm for stopping wire feeding to wire feeding controller 15. Receiving the signal, wire feeding controller 15 stops the power supply to motor 3 of wire feeding controller 18. First sequence controller 13 outputs instruction signal Vo to welding output section 20 so as to stop the supply of welding power to the welding wire and the work. At the same time, first sequence controller 13 outputs signal Vg for closing electromagnetic valve 2 to electromagnetic valve controller 14. Receiving the signal, electromagnetic valve controller 14 stops the DC voltage supply to electromagnetic valve 2 via electromagnetic-valve driving power input section 12. Through the procedures above, the feeding of welding wire, welding output, and the shielding gas supply stop, so that the welding is completed.

In a conventional arc welding device, to determine the presence or absence of the self-holding operation (i.e., to switch between the normal operation and the self-holding operation) and to determine a welding-current setup value and a welding-voltage setup value employed for the beginning and the ending stages of the welding, a welding worker has to operate first operation setting section 16 and third setup section 17 of arc-welding power source 19. Usually, wire feeding device 18 is disposed in the periphery of the welding site, whereas arc-welding power source 19 is fixed in a place; and in most cases, the place is distant from the welding worker and wire feeding device 18. Particularly, in the welding work in shipbuilding, arc-welding power source 19 is located far from the welding site.

In such a case having a great distance between the welding worker (and wire feeding device 18) and arc-welding power source 19, the welding work has difficulties in setting sequence operation and controlling welding current or other values. Each time switching between the normal operation and the self-holding operation so as to be suitable for welding positions or each time controlling the setup values of the third welding current and the third welding voltage, the welding worker has to leave the site to change the setting, for example, of the sequence operation and the setup value of welding current of arc-welding power source 19 situated at a place far from the site. The conventional structure, as described above, has hampered on-the-spot control of sequence operation and setup values at the welding site.

If first operation setting section 16 (for determining the sequence operation) and third setup section 17 (for controlling the welding current and other setup values) are formed in wire feeding device 18—not in arc-welding power source 19, the inconveniency can be eliminated. To form sections 17 and 18 in wire feeding device 18, an additional connection line is needed between the two devices so that a switching signal of the sequence operation is transmitted from wire feeding device 18 to arc-welding power source 19. However, the conventional wiring structure has difficulty in additionally forming the connection line described above.

That is, the problem above has not been addressed without change in the structure of arc-welding power source 19. Citation List Patent Literature PTL1

Japanese Unexamined Patent Application Publication No. 57-81966

SUMMARY OF THE INVENTION

To address the problem above, the present invention provides a wire feeding device capable of switching between the self-holding operation and the normal operation and adjusting the setup values of welding current and welding voltage. In addition, the structure of the present invention has no increase in connection lines between the arc-welding power source and the wire feeding device, compared to the number of the lines in a conventional structure. The wire feeding device of the present invention is connected to a startup switch to give instruction on starting/ending the welding and to an arc-welding power source for welding output. The wire feeding device of the present invention has a current detector, a startup signal input section, a startup signal output section, an electromagnetic valve, an electromagnetic-valve driving power input section, a first setup section, a second setup section, and a sequence controller. Detecting arc generation between a welding wire and a work, the current detector outputs an on-state current detection signal. The startup signal input section receives a startup signal from the startup switch. The startup signal output section outputs the startup signal to the arc-welding power source. The electromagnetic valve supplies shielding gas. The electromagnetic-valve driving power input section receives driving power from the arc-welding power source and drives the electromagnetic valve. The first setup section determines a first welding-current setup value and a first welding-voltage setup value as the welding conditions. The second setup section determines a second welding-current setup value and a second welding-voltage setup value as the welding conditions.

According to the outputs received from the startup signal input section, the first setup section, the second setup section, and the current detector, the sequence controller outputs an on/off signal of welding output, a welding-current setup value, and a welding-voltage setup value. The wire feeding device of the present invention further contains an operation setting section, a first transmission path, and a second transmission path. The self-holding operation is a sequence operation in which the on/off signal and the setup values of welding current and welding voltage are transmitted to the arc-welding power source.

The operation setting section determines whether the sequence controller performs the self-holding operation or not. The first transmission path transmits the startup signal of the startup switch from the startup signal input section to the startup signal output section, bypassing the sequence controller. The second transmission path transmits the startup signal of the startup switch as an on/off signal from the startup signal input section to the startup signal output section via the sequence controller. According to the wire feeding device, a driving power line to supply driving power to the sequence controller is connected parallel to a driving power line for the electromagnetic valve. The driving power for the sequence controller is fed from the arc-welding power source via the electromagnetic-valve driving power input section.

According to the structure above, when the electromagnetic valve of the wire feeding device is driven by electric power supplied from the arc-welding power source to the wire feeding device, the electric power is also fed to the sequence controller so as to control the self-holding operation. The present invention provides a structure in which a startup signal fed from the startup switch and a startup signal fed from the sequence controller are transmitted through circuits connected in parallel to the arc-welding power source. The circuit structure above allows the wire feeding device to determine the presence or absence of the self-holding operation and to control setup values of welding current and welding voltage, without adding change to conventional wiring connection between the wire feeding device and the arc-welding power source. That is, the wire feeding device of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 schematically shows the structure of the wire feeding device and the arc-welding power source, which form the arc welding device in accordance with a first exemplary embodiment of the present invention.

Fig. 2 is a timing chart illustrating output signals fed from the wire feeding device and the arc-welding power source and the workings of the signals in accordance with the first exemplary embodiment.

Fig. 3 schematically shows a wire feeding device and an arc-welding power source, which form a conventional arc welding device.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described as follows with reference to the accompanied drawings. In the second and third embodiments, like components are labeled with like reference numerals with respect to the preceding embodiments, and hence, the description thereof will be omitted.

FIRST EXEMPLARY EMBODIMENT

Fig. 1 schematically shows the structure of the wire feeding device and the arc-welding power source, which form the arc welding device in accordance with the first exemplary embodiment of the present invention. Fig. 2 is a timing chart illustrating output signals fed from the wire feeding device and the arc-welding power source and the workings of the signals in accordance with the embodiment.

As shown in Fig. 1, startup switch 1, which gives instruction of welding start and welding end, is connected to wire feeding device 18. Startup switch 1 is disposed, for example, in an arc welding torch or in a peripheral device (not shown).

Wire feeding device 18 has electromagnetic valve 2, motor 3, second operation setting section 4, first setup section 5, second setup section 6, second sequence controller 7, current detector 8, startup signal input section 9, startup signal output section 10, setup-value output section 11, and electromagnetic-valve driving power input section 12. Electromagnetic valve 2 supplies the arc welding site with shielding gas or stops the gas supply. Motor 3 feeds a welding wire (not shown). Second operation setting section 4 determines whether second sequence controller 7 performs the self-holding operation or not (i.e., second sequence controller 7 performs the self-holding operation or the normal operation). First setup section 5 determines a first welding-current setup value and a first welding-voltage setup value, which are the welding conditions of normal welding (steady-stage welding). Second setup section 6 determines a second welding-current setup value and a second welding-voltage setup value, which are the welding conditions of the beginning-stage welding before the normal welding and the ending-stage welding after the normal welding. Second sequence controller 7 performs sequence control. Current detector 8 detects welding current. Startup signal input section 9 receives a startup signal from startup switch 1. Startup signal output section 10 outputs the startup signal to arc-welding power source 19. Receiving the setup values determined in first setup section 5 or in second setup section 6, setup value output section 11 outputs them to arc-welding power source 19. Electromagnetic-valve driving power input section 12 receives electric power from electromagnetic valve controller 14 of arc-welding power source 19 so as to drive electromagnetic valve 2.

As described above, second operation setting section 4 determines presence or absence of the self-holding operation by second sequence controller 7. According to the setting of the self-holding operation and an operating state of startup switch 1, second sequence controller 7 controls not only output of the startup signal transmitted to first sequence controller 13 but also output of the setup values determined in first setup section 5 and second setup section 6.

Arc-welding power source 19 has first sequence controller 13, electromagnetic valve controller 14, wire feeding controller 15, first operation setting section 16, third setup section 17, and welding output section 20. First sequence controller 13 performs sequence control. Electromagnetic valve controller 14 supplies electric power to electromagnetic valve 2 of wire feeding device 18 or stops the power supply. Wire feeding controller 15 supplies electric power to motor 3 of wire feeding device 18 or stops the power source. First operation setting section 16 determines whether first sequence controller 13 performs the self-holding operation or not. Third setup section 17 determines a third welding-current setup value and a third welding-voltage setup value, which are the welding conditions of the beginning-stage welding before the normal welding and the ending-stage welding after the normal welding. According to the presence or absence of the self-holding operation and an operating state of startup switch 1, first sequence controller 13 controls the followings: welding output of welding output section 20; open/close of electromagnetic valve 2; and operation/non-operation of motor 3.

Although Fig. 1 does not show, one end of welding output of arc-welding power source 19 is electrically connected to the welding wire and the other end of the welding output is electrically connected to the work to be welded. Generating an arc by supplying electric power between the welding wire and the work, the welding is carried out.

As shown in Fig. 1, startup switch 1 is connected to startup signal input section 9 of wire feeding device 18. The startup signal from startup switch 1 is fed to startup signal input section 7a of second sequence controller 7 via startup signal input section 9. Wire feeding device 18 has a signal transmission path through which the startup signal fed from startup switch 1 is transmitted, via startup signal input section 9, to startup signal output section 10. The transmission path (hereinafter referred to as the first transmission path) bypasses second sequence controller 7.

First setup section 5 and second setup section 6 of wire feeding device 18 are connected to current/voltage setup input CVSI of second sequence controller 7. Current/voltage setup output CVSO of second sequence controller 7 is connected to current/voltage setup input Ws of first sequence controller 13 of arc-welding power source 19. Current detection output CDO of current detector 8 is connected to current detection input CD of second sequence controller 7. Second operation setting section 4 is connected to setup signal input SI of second sequence controller 7. Startup signal output section TS2 of second sequence controller 7 is connected, via startup signal output section 10, to startup signal input section TS3 of first sequence controller 13 of arc-welding power source 19. That is, signal TS from startup switch 1 is fed to startup signal input section 7a of second sequence controller 7 via startup signal input section 9. Further, the signal is transmitted as an on/off signal from startup signal output section TS2 of second sequence controller 7 to startup signal output section 10 (hereinafter, the transmission path—through which signal TS is transmitted from startup signal input section 9 to startup signal output section 10 via second sequence controller 7—is referred to as the second transmission path).

In arc-welding power source 19, first operation setting section 16 is connected to setup signal input SI2 of first sequence controller 13. The output from first sequence controller 13 is connected to electromagnetic valve controller 14, wire feeding controller 15, and welding output section 20. The output of electromagnetic valve controller 14 is connected to electromagnetic valve 2 via electromagnetic-valve driving power input section 12 of wire feeding device 18. The output of electromagnetic valve controller 14 is also connected to driving power source Vcc of second sequence controller 7 of wire feeding device 18.

The output of wire feeding controller 15 is connected to motor 3 of wire feeding device 18.

In a case where second operation setting section 4 determines that second sequence controller 7 of wire feeding device 18 performs the self-holding operation, the device works as follows. After a startup signal is turned in the on state (first-time on), a current detection signal detects welding current and turns in the on state. Receiving the startup signal and current detection signal both in the on state, second sequence controller 7 effects control of startup signal output section TS2 so as to output a turned-on startup signal. Current/voltage setup input CVSI of second sequence controller 7 receives setup values from second setup section 6 and outputs them to current/voltage setup output CVSO. Upon detecting an off-state (first-time off) startup signal after setting the output signal of startup signal output section TS2 to the on state, second sequence controller 7 outputs a setup value received from first setup section 5 to current/voltage setup output CVSO, while maintaining the on state of the output signal from startup signal output section TS2. After that, upon detecting an on-state (second-time on) startup signal, second sequence controller 7 outputs a setup value received from second setup section 6 to current/voltage setup output CVSO, while maintaining the on state of the output signal from startup signal output section TS2. Further, upon detecting an off-state (second-time off) startup signal, second sequence controller 7 switches the on state of the output signal from startup signal output section TS2 into the off state and outputs the setup value received from first setup section 5 to current/voltage setup output CVSO.

When startup signal input section 7a receives an off-state (first-time off) startup signal after the first-time on state, (where, the current detection signal is maintained in the off state), the output signal from startup signal output section TS2 is turned in the off state and current/voltage setup output CVSO outputs the setup values from first setup section 5.

When second operation setting section 4 determines the absence of the self-holding operation (i.e. second sequence controller 7 performs the normal operation), the output signal of startup signal output section TS2 of second sequence controller 7 is turned into the off state and current/voltage setup output CVSO outputs the setup values from first setup section 5.

Hereinafter, the workings of wire feeding device 18 that constitutes the arc welding device of the embodiment will be described with reference to Fig. 1 and Fig. 2.

First, the description below is on the same workings between the self-holding operation and the normal operation in second sequence controller 7 of wire feeding device 18.

Suppose that first operation setting section 16 of arc-welding power source 19 determines the absence of the self-holding operation. In response to an on-state signal fed into startup signal input section TS3 of first sequence controller 13 of arc-welding power source 19, first sequence controller 13 effects control of electromagnetic valve controller 14 so as to open electromagnetic valve 2 of wire feeding device 18. Further, according to welding conditions (i.e. a welding-current setup value and a welding-voltage setup value) fed into current/voltage setup input Ws, controller 13 effects control of welding output section 20 so as to supply welding current to the welding wire and the work. At the same time, first sequence controller 13 effects control of wire feeding controller 15 so as to drive motor 3 of wire feeding device 18.

In this way, the welding device starts to feed shielding gas, welding output, and a welding wire. Welding thus starts. After the start of welding, upon receiving an off-state signal at startup signal input section TS3, first sequence controller 13 stops welding output and closes electromagnetic valve 2, and stops motor 3 to complete the welding.

Next, the description below is on a case where second operation setting section 4 of wire feeding device 18 is switched to the self-holding operation mode by a welding worker.

To start welding, startup switch 1 is turned in the on state (that corresponds to time A of timing chart TS in Fig. 2).

The output signal of startup switch 1 is fed into startup signal input section 9 and directly transmitted to startup signal output section 10. At this time, the signal passes through the first transmission path, bypassing second sequence controller 7. Further, the signal is fed into startup signal input section TS3 of first sequence controller 13 of arc-welding power source 19 as a startup signal. To supply shielding gas, first sequence controller 13 outputs an instruction signal for opening electromagnetic valve 2 to electromagnetic valve controller 14 (at time A of timing chart Vg in Fig. 2). Receiving the signal, electromagnetic valve controller 14 applies DC voltage (electric power), via electromagnetic-valve driving power input section 12, to electromagnetic valve 2 of wire feeding device 18. The procedures above allow shielding gas to be supplied.

First sequence controller 13 outputs a control signal so that welding output section 20 determines welding output according to the welding-current setup value and the welding-voltage setup value obtained at current/voltage setup input Ws. Receiving the control signal, welding output section 20 supplies the welding wire and the work with welding power. Further, first sequence controller 13 outputs an instruction signal for starting wire feeding to wire feeding controller 15 (at time A of timing chart Vm in Fig. 2). Wire feeding controller 15 supplies electric power to motor 3 of wire feeding device 18, starting the wire feeding.

In this way, the welding device starts to feed shielding gas, welding output, and a welding wire. Welding thus starts.

As shown in Fig. 1, electromagnetic valve controller 14 of arc-welding power source 19 supplies DC voltage (electric power) not only to electromagnetic valve 2 of wire feeding device 18 but also to driving power source Vcc of second sequence controller 7 (at time A of timing chart Vcc in Fig. 2), allowing second sequence controller 7 to get into operation.

The description below shows the workings of the device when second sequence controller 7 is not in operation, i.e., the DC voltage (electric power) from electromagnetic valve controller 14 of arc-welding power source 19 is not applied to driving power source Vcc.

In that case, the output signal from startup signal output section TS2 of second sequence controller 7 is in the off state, and current/voltage setup output CVSO outputs the setup value of first setup section 5 received at current/voltage setup output CVSI (as shown at time A of timing chart Ws in Fig. 2). When second sequence controller 7 gets into an operating state, current/voltage setup output CVSO outputs the setup value of second setup section 6 received at current/voltage setup input CVSI, while the output signal of startup signal output section TS2 of second sequence controller 7 is maintained in the off state.
Welding output section 20 supplies a welding wire and a work with electric power to generate an arc between them. In response to arc generation, the output signal of current detection output CDO of current detector 8 is turned into the on state (as shown at time B of timing chart CD in Fig. 2). When the output signal of current detection output CDO of current detector 8 and the output signal of startup switch 1 are both in the on state, startup signal output section TS2 of second sequence controller 7 outputs a turned-on signal (, which corresponds to time B of timing chart TS2 in Fig. 2).

The description below is on the case where startup switch 1 is turned off before arc generation between the welding wire and the work, i.e., while the output signal of welding detection output CDO of current detector 8 is maintained in the off state (, which corresponds to time F of timing chart TS in Fig. 2).
At this time, the output signal of startup signal output section TS2 of second sequence controller 7 in the off state, and the startup signal of startup switch 1 is in the off state, too. Therefore, startup signal output section 10 has off-state output. In response to the off-state signal from startup signal output section 10 (i.e., the off-state input signal of startup signal input section TS3), first sequence controller 13 outputs an instruction signal for stopping wire feeding to wire feeding controller 15. Receiving the signal, wire feeding controller 15 stops power supply to motor 3 of wire feeding device 18. Further, first sequence controller 13 outputs a signal for stopping welding output to welding output section 20, so that welding output section 20 stops the supply of welding power between the welding wire and the work. In addition, first sequence controller 13 outputs a signal for closing electromagnetic valve 2 to electromagnetic valve controller 14. Receiving the signal, electromagnetic valve controller 14 stops the DC voltage supply not only to electromagnetic valve 2 via electromagnetic-valve driving power input section 12 but also to driving power source Vcc of second sequence controller 7.

Through the procedures above, the supply of welding output, wire feeding, and shielding gas stops. Welding is thus completed.

Next, the output signal of current detection output CDO of current detector 8 is turned in the on state, and after that, startup switch 1 is turned in the off state (first-time off). The timing above corresponds to time C of timing chart TS in Fig. 2. The output signal of startup switch 1 is fed into second sequence controller 7 via startup signal input section 9. Startup signal output section TS2 of second sequence controller 7 is determined in the state of the self-holding operation. Therefore, startup signal output section TS2 is kept in the on state. Accordingly, current/voltage setup output CVSO outputs the setup value of first setup section 5 obtained at current/voltage setup input CVSI.

In the period between the first-time off and the second-time on of startup switch 1 (corresponding to between time C and time D of timing chart TS in Fig. 2), the startup signal of startup switch 1 is in the off state, but the output signal from second sequence controller 7, which is connected in parallel to startup switch 1, is in the on state (see timing chart TS2 in Fig. 2). Therefore, the startup signal input of first sequence controller 13 of arc-welding power source 19 is maintained in welding start condition. During the period above—between the first-time off and the second-time on of startup switch 1, current/voltage setup output CVSO outputs the setup value of first setup section 5 obtained at current/voltage setup input CVSI.

Further, during the period between the second-time on and the second-time off of startup switch 1 (corresponding to between time D and time E of timing chart TS in Fig. 2), the startup signal output of second sequence controller 7 is set in the state of the self-holding operation. Therefore, the startup signal output of second sequence controller 7 is maintained in the on state, and current/voltage setup output CVSO outputs the setup value of second setup section 6 obtained at current/voltage setup input CVSI, thereby changing welding condition (at time D of timing chart Ws in Fig. 2).

After that, startup switch 1 is turned in the off state (second-time off), which corresponds to time E of timing chart TS in Fig. 2. In response to the second-time off, current/voltage setup output CVSO of second sequence controller 7 outputs the setup value of first setup section 5 obtained at current/voltage setup input CVSI, and the output signal of the startup signal output of second sequence controller 7 is turned in the off state (at time E of timing chart TS2 in Fig. 2). Both of startup switch 1 and startup signal output TS2 have off-state output, accordingly, the output of startup signal output section 10 is turned in the off state.

In response to the turned-off startup signal input (at time E of timing chart TS3 in Fig. 2), first sequence controller 13 outputs a signal for stopping welding output to welding output section 20, so that welding output section 20 stops the supply of welding power between the welding wire and the work. Further, first sequence controller 13 outputs an instruction signal for stopping wire feeding to wire feeding controller 15. Receiving the signal, wire feeding controller 15 stops power supply to motor 3 of wire feeding device 18. In addition, first sequence controller 13 outputs a signal for closing electromagnetic valve 2 to electromagnetic valve controller 14. Through the procedures above, the supply of welding output, wire feeding, and shielding gas stops. Welding is thus completed.

In a case where first operation setting section 16 of arc-welding power source 19 determines that first sequence controller 13 performs the normal operation (i.e., the state having no self-holding operation), the device works as follows.

The output signal of startup switch 1 is transmitted from startup signal input section 9 to startup signal output section 10. At this time, the signal passes the first transmission path, bypassing second sequence controller 7. Whenever second operation setting section 4 is set in the normal operation, startup signal output section TS2 of second sequence controller 7 is in the off state. In this case, first sequence controller 13 of arc-welding power source 19 receives the output signal of startup switch 1 as startup signal input. Specifically, when startup switch 1 is turned into the on state (e.g., the state in which a torch switch is remained on), welding starts. On the other hand, when startup switch 1 is turned into the off state (e.g., the state in which a torch switch is remained off), welding completes.

As described above, when second operation setting section 4 is set in the normal operation mode, the welding device performs the normal operation in welding start and welding end.

Whenever second operation setting section 4 is set in the normal operation mode, current/voltage setup output CVSO of second sequence controller 7 outputs the setup value of first setup section 5 obtained at current/voltage setup input CVSI.

As described above, wire feeding device 18 of the present invention is connected to startup switch 1 to give instruction signal on welding start and welding end and to arc-welding power source 19 to provide welding output. Wire feeding device 18 of the present invention has current detector 8, startup signal input section 9, startup signal output section 10, electromagnetic valve 2, electromagnetic-valve driving power input section 12, first setup section 5, second setup section 6, sequence controller 7, operation setting section 4, a first transmission path, and a second transmission path. According to wire feeding device 18, the driving power line to supply driving power to sequence controller 7 is connected parallel to the driving power line for electromagnetic valve 2. The driving power for sequence controller 7 is fed from arc-welding power source 19 via electromagnetic-valve driving power input section 12. Detecting arc generation between the welding wire and the work, current detector 8 outputs a turned-on current detection signal. Startup signal input section 9 receives a startup signal from startup switch 1. Startup signal output section 10 outputs the startup signal to arc-welding power source 19. Electromagnetic valve 2 supplies shielding gas. Electromagnetic-valve driving power input section 12 receives driving power to drive electromagnetic valve 2 from arc-welding power source 19. First setup section 5 determines a first welding-current setup value and a first welding-voltage setup value as the welding conditions. Second setup section 6 determines a second welding-current setup value and a second welding-voltage setup value as the welding conditions. According to the outputs received from startup signal input section 9, first setup section 5, second setup section 6, and current detector 8, sequence controller 7 outputs an on/off signal of welding output, a welding-current setup value, and a welding-voltage setup value. The self-holding operation is a sequence operation in which the on/off signal and the setup values of welding current and welding voltage are transmitted to arc-welding power source 19. Operation setting section 4 determines whether sequence controller 7 performs the self-holding operation or not. The first transmission path transmits the signal of startup switch 1 from startup signal input section 9 to startup signal output section 10, bypassing sequence controller 7. The second transmission path transmits the startup signal of startup switch 1 as an on/off signal from the startup signal input 9 section to the startup signal output section 10 via sequence controller 7.

In the structure above, when electromagnetic valve 2 of wire feeding device 18 is driven by electric power supplied from arc-welding power source 19 to wire feeding device 18, the electric power is also fed to sequence controller 7 of wire feeding device 18 so as to control the self-holding operation. The present invention provides a structure in which a startup signal fed from startup switch 1 and a startup signal fed from sequence controller 7 are transmitted from wire feeding device 18 through circuits connected in parallel to arc-welding power source 19. The circuit structure above allows wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change (i.e. increase in number of connection lines) to conventional wiring connection between wire feeding device 18 and arc-welding power source 19. That is, wire feeding device 18 of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

That is, when electromagnetic valve 2 is driven by electric power fed from electromagnetic valve controller 14 of arc-welding power source 19, the electric power fed from electromagnetic valve controller 14 also drives second sequence controller 7 of wire feeding device 18, allowing controller 7 to start operation. In the structure above, a startup signal of startup switch 1 and a startup signal (on/off signal) fed from second sequence controller 7 are transmitted to the startup signal input section of arc-welding power source 19 through the circuits connected in parallel. The circuit structure above enables wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control the setup values of welding current and welding voltage employed in the beginning stage and the ending stage of welding. Besides, the additional function of the wire feeding device is obtained, as described above, without increase in number of lines to conventional wiring connection.

As described above, wire feeding device 18 having aforementioned functions—switching between the self-holding operation and the normal operation, and controlling the welding current setup value and the welding voltage setup value of welding in the beginning and the ending stages of welding—eliminates the conventional inconvenience. That is, such structured wire feeding device enables the welding worker to have on-the-spot operation, such as switching the sequence operation and controlling the setup values of welding current and welding voltage, with no need to move over the location of arc-welding power source 19. Particularly, it is greatly useful for the welding operation in which arc-welding power source 19 is located far from wire feeding device 18.

Sequence controller 7 receives an output signal from startup switch 1 and an output signal from current detector 8. Upon detecting an on-state output signal from startup switch 1 and an on-state output signal from current detector 8, sequence controller 7 gets into the operation mode. When operation setting section 4 is set in the self-holding operation mode, the output signal of setup switch 1 is turned in the on state, and in response to the turned-on output signal fed from current detector 8, the output signal of startup switch 1 is turned in the off state. During the period from the time on which the output signal of current detector 8 is turned on successive to the first-time on of startup switch 1 until the time on which the second-time off of startup switch 1 after the first-time off and then the second-time on, sequence controller 7 outputs on-state welding output to arc-welding power source 19. On the other hand, sequence controller 7 outputs off-state welding output to arc-welding power source 19 in a period other than the aforementioned period and in the non-operating state of sequence controller 7. In a case where operation setting section 4 determines that sequence controller 7 has no self-holding operation, in response to an on-state output signal from startup switch 1, sequence controller 7 outputs a startup signal that turns on welding output to arc-welding power source 19 through the first transmission path. At the same time, sequence controller 7 may output the first welding-current setup value and the first welding-voltage setup value of first setup section 5 to arc-welding power source 19. The structure above allows wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change to conventional wiring connection between wire feeding device 18 and arc-welding power source 19. As a result, wire feeding device 18 of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

In the structure above, first setup section 5 may determine the first welding-current setup value and the first welding-voltage setup value so as to be used for the welding conditions of the steady-stage welding and the beginning-stage welding before the steady-stage welding. Second setup section 6 may determine the second welding-current setup value and the second welding-voltage setup value so as to be used for the welding conditions of the ending-stage welding after the steady-stage welding.

The structure above allows wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change to conventional wiring connection between wire feeding device 18 and arc-welding power source 19. As a result, wire feeding device 18 of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

During the period from the second-time on (that follows the first-time on and the first-time off) of startup switch 1 until the second-time off, sequence controller 7 may output setup values of welding current and welding voltage determined in second setup section 6 to arc-welding power source 19. In that case, in a period except for the aforementioned period and, in the non-operating state of sequence controller 7, first welding-current setup value and first welding-voltage setup value determined in first setup section 5 are transmitted to arc-welding power source 19.

The structure above allows wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change to conventional wiring connection between wire feeding device 18 and arc-welding power source 19. As a result, wire feeding device 18 of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

Further, in the structure of the present invention, first setup section 5 may determine the first welding-current setup value and the first welding-voltage setup value, which are employed for the welding conditions of the steady-stage welding. Second setup section 6 may determine the second welding-current setup value and the second welding-voltage setup value, which are employed for the welding conditions of the beginning-stage welding before the steady-stage welding and the ending-stage welding after the steady-stage welding.

The structure above allows wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change to conventional wiring connection between wire feeding device 18 and arc-welding power source 19. As a result, wire feeding device 18 of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

Further, the following output control is another possible structure. The setup values of welding current and welding voltage determined in second setup section are transmitted to arc-welding power source 19 during the following two periods: the period between the first-time on and the first-time off of the output signal of startup switch 1; and the period between the second-time on and the second-time off of the output signal of startup switch 1. On the other hand, in a period other than the aforementioned two periods and in the non-operating mode of sequence controller 7, first setup values of welding current and welding voltage determined in second setup section 6 are transmitted to arc-welding power source 19.
The structure above allows wire feeding device 18 not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change to conventional wiring connection between wire feeding device 18 and arc-welding power source 19. As a result, wire feeding device 18 of the present invention enables the welding worker at the welding site to have on-the-spot setting and change of welding operation and setup values used for welding.

Suppose that wire feeding device 18 has the following functions: switching between the self-holding operation mode and the non self-holding operation mode; and controlling the setup values of welding current and welding voltage employed in the beginning stage and the ending stage of welding. In this case, too, the connection wiring between wire feeding device 18 and arc-welding power source 19 has no increase in number of connection lines, and accordingly, arc-welding power source 19 has no need to have additional change for the increase in number of connection lines.

Although Fig. 1 shows the example where electromagnetic valve controller 14 supplies electromagnetic valve 2 with DC driving voltage, AC voltage may be employed. In that case, a rectifying circuit is formed in second sequence controller 7 so that the AC power fed from electromagnetic valve controller 14 is rectified to obtain DC power as driving power source of second sequence controller 7.

In the self-holding operation described above, each of the welding-current setup value and the welding-voltage setup value is the same between the beginning stage and the ending stage but is different from that employed in the steady stage. However, it is not limited to. In some cases, each of the welding-current setup value and the welding-voltage setup value is the same between the beginning stage and the steady stage and is different from that in the ending stage. In that case, in the beginning stage and the steady stage of welding, second sequence controller 7 receives the setup values of first setup section 5 through current/voltage setup input CVSI and outputs them through current/voltage setup output CVSO. In the ending stage of welding, second sequence controller 7 receives the setup values of second setup section 6 through current/voltage setup input CVSI and outputs them through current/voltage setup output CVSO.

In the description above, the period between the time on which startup switch 1 is turned on (first-time on) and the time on which startup switch 1 is turned off (first-time off) corresponds to the beginning stage of welding. The successive period between the first-time off and the time on which startup switch 1 is turned on again (second-time on) corresponds to the steady stage of welding. Further, the successive period between the second-time on and the time on which startup switch 1 is turned off again (second-time off) corresponds to the ending stage of welding.

INDUSTRIAL APPLICABILITY

The structure of the present invention, as described above, allows the wire feeding device not only to switch between the self-holding operation and the normal operation but also to control setup values of welding current and welding voltage, without additional change to conventional wiring connection between the wire feeding device and a conventional arc-welding power source. The present invention is thus useful for the wire feeding device of an arc welding device that offers welding work by wire feeding and arc generation.

REFERENCE MARKS IN THE DRAWINGS

1 startup switch
2 electromagnetic valve
3 motor
4 second operation setting section
5 first setup section
6 second setup section
7 second sequence controller 7a,
9 startup signal input section
8 current detector
10 startup signal output section
11 setup value output section
12 electromagnetic-valve driving power input section
13 first sequence controller
14 electromagnetic valve controller
15 wire feeding controller
16 first operation setting section
17 third setup section
18 wire feeding device
19 arc-welding power source
20 welding output section

CLAIMS

1. A wire feeding device to be connected to a startup switch to give instruction on welding start and welding end and to an arc-welding power source for welding output, the device comprising:

a current detector to output an on-state current detection signal when detecting arc generation between a welding wire and a work;

a startup signal input section to receive a startup signal from the startup switch;

a startup signal output section to output the startup signal to the arc-welding power source;

an electromagnetic valve to supply shielding gas;

an electromagnetic-valve driving power input section to receive driving power for driving the electromagnetic valve from the arc-welding power source;

a first setup section to determine a first welding-current setup value and a first welding-voltage setup value of welding conditions;

a second setup section to determine a second welding-current setup value and a second welding-voltage setup value of the welding conditions;

a sequence controller to output an on/off signal of welding output, a welding-current setup value, and a welding-voltage setup value according to outputs received from the startup signal input section, the first setup section, the second setup section, and the current detector;

an operation setting section to determine whether or not the sequence controller performs a self-holding operation as sequence operation in which the on/off signal of welding output and the welding-current setup value and the welding-voltage setup value are transmitted to the arc-welding power source;

a first transmission path to transmit a signal of the startup switch from the startup signal input section to the startup signal output section, bypassing the sequence controller; and

a second transmission path to transmit a signal of the startup switch from the startup signal input section, via the sequence controller, to the startup signal output section,

wherein, a driving power line to supply driving power to the sequence controller is connected parallel to a driving power line for the electromagnetic valve so that driving power for the sequence controller is fed from the arc-welding power source via the electromagnetic-valve driving power input section.

2. The wire feeding device of claim 1, wherein the sequence controller receives an output signal from the startup switch and an output signal from the current detector and gets into operation upon receiving turned-on output signals from the startup switch and the current detector;

in a case where the operation setting section is set in a self-holding operation mode, in a period from a time on which the output signal of the current detector is turned on successive to first-time on of the output signal of the startup switch until a time on which the output signal of the startup switch is turned second-time off after first-time off and then second-time on, the sequence controller outputs an on/off signal indicating on-state welding output to the arc-welding power source, whereas in a period except for the period from the time on which the output signal of the current detector is turned on successive to the first-time on of the output signal of the startup switch until the second-time off of the startup switch and, when the sequence controller is not in operation, an on/off signal indicating off-state welding output is transmitted to the arc-welding power source; and

in a case where the operation setting section is set in a non-self-holding operation mode, in response to a turned-on output signal of the startup switch, the sequence controller outputs a startup signal indicating on-state welding output to the arc-welding power source via the first transmission path, at the same time, the sequence controller outputs the first welding-current setup value and the first welding-voltage setup value determined in the first setup section to the arc-welding power source.

3. The wire feeding device of claim 1 or 2, wherein the first setup section determines the first welding-current setup value and the first welding-voltage setup value used for welding conditions of a steady stage of welding and a beginning stage of welding before the steady stage of welding, and the second setup section determines the second welding-current setup value and the second welding-voltage setup value used for welding conditions of an ending stage of welding after the steady stage of welding.

4. The wire feeding device of claim 3, wherein, in a period from the second-time on of the startup switch after the first-time on and the first-time off until the second-time off, the second welding-current setup value and the second welding-voltage setup value determined in the second setup section are transmitted to the arc-welding power source; and

in a period except for the period between the second-time on and the second-time off of the startup switch and, when the sequence controller is not in operation, the first welding-current setup value and the first welding-voltage setup value determined in the first setup section are transmitted to the arc-welding power source.

5. The wire feeding device of claim 1 or 2, wherein the first setup section determines the first welding-current setup value and the first welding-voltage setup value used for welding conditions of a steady stage of welding, and the second setup section determines the second welding-current setup value and the second welding-voltage setup value used for welding conditions of a beginning stage of welding before the steady stage of welding and an ending stage of welding after the steady stage of welding.

6. The wire feeding device of claim 5, wherein, during two periods of a period between the first-time on and the first-time off of the startup switch and a period between the second-time on and the second-time off of the startup switch, the second welding-current setup value and the second welding-voltage setup value determined in the second setup section are transmitted to the arc-welding power source; and
in a period except for the two periods and, when the sequence controller is not in operation, the first welding-current setup value and the first welding-voltage setup value determined in the first setup section are transmitted to the arc-welding power source.