Welding equipment and welding method

Abstract

This welding device comprises: a wire feed device that, by rotation of a DC motor, feeds a welding wire to a welding torch or rewinds the welding wire from the welding torch in a non-consumable electrode type arc welding device and a consumable electrode type arc welding device; and a control unit that supplies power to the DC motor to drive the DC motor. The control unit, when stopping the DC motor or decreasing the feed speed of the welding wire after having supplied first power which has either a positive polarity or a negative polarity to the DC motor to feed or rewind the welding wire, supplies second power which has a polarity opposite to that of the first power to the DC motor.

Description

[Technical Field]

[0001] The present disclosure relates to welding devices and methods. [Background technology]

[0002] Patent Document 1 discloses a semi-automatic welding method in which welding is performed while a welding wire is continuously fed to a welding torch by a feeder. In this method, prior to the start of welding, the welding wire is reversed and retracted toward the welding tip of the welding torch until its tip reaches a reference position, and then feeding of the welding wire begins. This semi-automatic welding method is characterized by temporarily stopping the feeding of the welding wire when the amount of welding wire protruding from the welding tip reaches a dimension suitable for starting welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-202629 Summary of the Invention

[0004] An object of the present disclosure is to stably feed a welding wire and improve the workability and quality of welding.

[0005] The present disclosure relates to a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, each of which includes a wire feeder that feeds a welding wire to a welding torch or rewinds the welding wire from the welding torch by rotation of a DC motor, and a control unit that supplies power to the DC motor to drive the DC motor, and the control unit supplies a first power having either a positive polarity or a negative polarity to the DC motor to feed or rewind the welding wire, and then, when the DC motor is stopped or the feeding speed of the welding wire is reduced, supplies a second power having a polarity opposite to that of the first power to the DC motor. the control unit supplies the second power to the DC motor for a second power supply time that is shorter than the time for which the first power was supplied to the DC motor; when changing the power supplied to the DC motor from a third power having a positive polarity to a fifth power having a positive polarity that is smaller than the third power, the control unit supplies the second power to the DC motor for the second power supply time; the control unit executes at least once a first control that changes the power supplied to the DC motor from the third power to the fifth power and then returns the power supplied to the DC motor to the third power again; the control unit supplies the third power or the fifth power to the DC motor and feeds the welding wire, and then supplies a fourth power having a negative polarity to the DC motor to rewind the welding wire, and when stopping the DC motor after rewinding the welding wire, supplies the second power to the DC motor for the second power supply time. To provide a welding device. The present disclosure also provides a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, each comprising: a wire feeder that feeds a welding wire to a welding torch or rewinds the welding wire from the welding torch by rotation of a DC motor; and a control unit that supplies power to the DC motor to drive the DC motor, wherein the control unit supplies a first power having either positive polarity or negative polarity to the DC motor to feed or rewind the welding wire, and then, when stopping the DC motor or slowing down the feeding speed of the welding wire, supplies a second power having a polarity opposite to that of the first power to the DC motor; the control unit supplies the second power to the DC motor for a second power supply time that is shorter than the time for which the first power was supplied to the DC motor; when changing the power supplied to the DC motor from a third power that is positive to a fifth power that is positive and less than the third power, the control unit supplies the second power to the DC motor for the second power supply time; when an operator turns on a switch of the wire feeder related to feeding of the welding wire, the control unit supplies the third power to the DC motor for the second power supply time; when the operator turns off the switch, the control unit changes the power supplied to the DC motor to the fifth power; when the operator turns on the switch after an inertia time that is longer than the second power supply time has elapsed since turning off the switch and then turns off the switch again, the control unit supplies the first power to the DC motor to rewind the welding wire; and when the DC motor is stopped after rewinding the welding wire, the control unit supplies the second power to the DC motor for the second power supply time.

[0006] The present disclosure also provides a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, each including a wire feeder that feeds welding wire to a welding torch or rewinds the welding wire from the welding torch by rotation of a DC motor, and a control unit that supplies power to the DC motor to drive the DC motor, wherein the control unit supplies a first power of either positive polarity or negative polarity to the DC motor to feed or rewind the welding wire, and then, when stopping the DC motor or slowing down the welding wire feed speed, supplies a second power of opposite polarity to the first power to the DC motor, and the control unit changes the power supplied to the DC motor in synchronization with a pulse signal output from a welding power source during pulse welding that alternates between a first welding current and a second welding current smaller than the first welding current.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0008] According to the present disclosure, the welding wire can be fed stably, and the workability and quality of welding can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of a welding system according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing an example of a welding wire feeding mode according to the present embodiment. [Figure 3] FIG. 10 is a diagram showing an example of a welding wire feeding mode according to the present embodiment. [Figure 4] FIG. 10 is a diagram showing an example of a welding wire feeding mode according to the present embodiment. [Figure 5] FIG. 10 is a diagram showing an example of a welding wire feeding mode according to the present embodiment. [Figure 6] FIG. 1 is a diagram showing an example of control of a current flowing through a DC motor according to a conventional technique. [Figure 7] FIG. 10 is a diagram showing an example of control of a current flowing through a DC motor according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Background to this embodiment) Semi-automatic Tungsten Inert Gas (TIG) welding is a type of arc welding in which a welding wire is fed to the welding point via a wire feed path by a wire feeder. In semi-automatic TIG welding, it is important to ensure that the welding wire protrusion length before welding is appropriate and that the welding wire is fed stably during welding in order to improve the workability and quality of the welding.

[0011] Patent Document 1 discloses a semi-automatic welding method in which, when a switch related to starting a welding torch is turned on to start welding, the feeder controls the welding wire to feed in the reverse direction, and the wire end contacts the end of the welding tip. After this contact is detected, the wire is fed in the forward direction, and the length of the welding wire protruding from the welding tip (i.e., the protrusion amount) is adjusted to an appropriate length before welding begins. However, to improve the workability and quality of welding, it is necessary to consider the effects of the inertia of the feeder (e.g., inertia associated with the rotation of the motor used for feeding control) that occurs when the feeder feeds the welding wire in the forward direction, and the variation in the feed amount that occurs due to slack in the welding wire within the feed path.

[0012] Hereinafter, with appropriate reference to the drawings, a detailed description will be given of embodiments specifically disclosing a welding apparatus and a welding method according to the present disclosure. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0013] First, a configuration diagram of a welding system according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a configuration diagram of a welding system according to this embodiment.

[0014] Welding system 100 according to this embodiment includes welding power source 10, wire feeder 20, welding torch 50, and switch 60.

[0015] A welding power source 10, which is an example of a power source, is connected to the wire feeder 20 and the welding torch 50 via power lines, and supplies the necessary power to the wire feeder 20 and the welding torch 50. The welding power source 10 is, for example, a dual-purpose AC / DC power source that can supply both AC and DC current. Note that the welding power source 10 is not limited to a dual-purpose AC / DC power source, and may be capable of supplying only DC or only AC. The welding power source 10 outputs, for example, approximately 200 A of DC or AC current, as an example of the necessary power. Note that the current value output by the welding power source 10 is merely an example and is not limited to 200 A.

[0016] Wire feeder 20 is connected to welding power source 10 and is driven by power (voltage) supplied from welding power source 10. Wire feeder 20 feeds welding wire 40 toward the tip of welding torch 50 via wire feed path 30 based on the power from welding power source 10. Note that welding power source 10 is not limited to being an external device of wire feeder 20, but may be built into wire feeder 20. A switch 60 related to the feeding of welding wire 40 is connected to wire feeder 20. Wire feeder 20 includes a control unit 21 and a welding wire feeder 22.

[0017] The control unit 21 functions as a controller that controls the overall operation of the wire feeder 20. The control unit 21 may be a semiconductor chip having at least one of electronic devices, such as a central processing unit (CPU), a digital signal processor (DSP), a graphical processing unit (GPU), or a field programmable gate array (FPGA), mounted on a control board (see above). The wire feeder 20 has a memory (not shown in FIG. 1 ), and the control unit 21 uses a random access memory (RAM) of the memory (not shown) during operation to temporarily store data generated or acquired by the control unit 21 in the RAM. The control unit 21 uses the power output from the welding power source 10 to control the power supplied to drive the DC motor of the welding wire feeder 22. In addition, the control unit 21 controls the power supplied to drive the DC motor of the welding wire feeder 22 based on a pulse synchronization signal output from the welding power source 10 in a pulse synchronization mode (see FIG. 4 ).

[0018] The welding wire feeder 22 has a direct current motor (hereinafter referred to as a DC (Direct Current) motor) that feeds the welding wire 40. The DC motor is, for example, a permanent magnet field type DC motor or an electromagnet field type DC motor. Note that the welding wire feeder 22 is not limited to a DC motor and may also have an alternating current (AC) motor that is driven by an alternating current power source. The welding wire feeder 22 supplies power to the DC motor based on instructions from the control unit 21 to drive the DC motor.

[0019] While welding is being performed, welding wire feeder 22 uses a DC motor to perform an operation of feeding (supplying) welding wire 40 in the forward direction toward the tip of welding torch 50 or an operation of feeding (retrieving) welding wire 40 in the reverse direction from the tip of welding torch 50.

[0020] One end of wire feed path 30 is connected to wire feeder 20, and the other end is connected to welding torch 50. Wire feed path 30 is, for example, a tube or cable through which welding wire 40 can be smoothly inserted. Wire feed path 30 is made of a material that can deform in accordance with the movement of welding torch 50. Wire feed path 30 is, for example, a flexible conduit. Note that wire feed path 30 is not limited to a flexible conduit.

[0021] The welding wire 40 is, for example, a filler wire made of stainless steel or the like. However, the welding wire 40 is not limited to a filler wire made of stainless steel or the like. The welding wire 40 is fed from the wire feeder 20 to the tip of the welding torch 50 through the wire feed path 30.

[0022] Welding torch 50 arc-welds welding point PL by supplying power output from welding power source 10 to an electrode disposed at the tip of welding torch 50. The electrode used in welding torch 50 is, for example, a tungsten electrode. Note that the electrode used in welding torch 50 is not limited to a tungsten electrode, and may be either a non-consumable electrode or a consumable electrode.

[0023] Switch 60 may output to the control unit a signal to change the feed speed of welding wire 40 by switching on and off, or may output to the control unit a signal to switch between starting and stopping the feed of welding wire 40. The signal to change the feed speed and the signal to switch between starting and stopping the feed are output to the control unit by switching on and off switch 60. The signal to change the feed speed and the signal to switch between starting and stopping the feed may be automatically switched by control unit 21.

[0024] Base metal cable 70 is a welding cable that connects the terminal of welding power source 10 to the welding point PL.

[0025] Next, a "continuous feeding mode" which is an example of a welding wire feeding mode according to the present embodiment will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of a welding wire feeding mode according to the present embodiment.

[0026] 2, the horizontal axis represents time, and the vertical axis represents the feed speed at each time of welding wire 40. Hereinafter, the feed speed of welding wire 40 will be referred to as the wire feed speed.

[0027] From time t0 to time t1, the wire feed speed is v0. Speed ​​v0 is 0 (zero), which means that no power is supplied to the DC motor of welding wire feeder 22. In other words, from time t0 to time t1, wire feeder 20 is not feeding welding wire 40.

[0028] At time t1, the wire feed speed becomes speed v1, which is greater than speed v0 in the positive direction. Speed ​​v1 is a finite positive speed. The positive speed represents the speed at which wire feeder 20 feeds the welding wire toward the tip of welding torch 50. At time t1, control unit 21 supplies a third power of positive polarity to the DC motor to change the wire feed speed from speed v0 to speed v1. This enables wire feeder 20 to feed welding wire 40 from welding wire feeder 22 at speed v1. From time t1 to time t2, wire feeder 20 feeds welding wire 40 to the tip of welding torch 50 at speed v1.

[0029] At time t2, control unit 21 supplies a fourth power having the opposite polarity to the third power, and sets the wire feed speed to a finite negative speed v2. Note that the fourth power may have the opposite polarity to the third power, or may simply have a negative polarity different from the polarity of the third power. The negative speed represents the speed at which wire feeder 20 reversely feeds (i.e., rewinds) welding wire 40 from welding torch 50 to wire feeder 20. Between time t2 and time t3, wire feeder 20 rewinds welding wire 40 to adjust the extension length from the tip of welding torch 50 to an appropriate length. In other words, wire feeder 20 adjusts the extension length of welding wire 40 to an appropriate length before starting the next welding.

[0030] At time t3, the control unit 21 stops supplying the fourth power to the DC motor, and the wire feed speed returns to v0. When stopping the supply of the fourth power to the DC motor, the control unit 21 supplies a second power having the opposite polarity to the fourth power for an extremely short time (hereinafter referred to as the second power supply time). The second power supply time is, for example, several tens of milliseconds. Note that the extremely short time is not limited to several tens of milliseconds. Furthermore, the second power supply time is not limited to a fixed value and may vary, for example, depending on the state of the DC motor's rotation speed and current immediately before the second power is supplied to the DC motor. Because the time shown in FIG. 2 is on the order of several seconds, the time during which the second power is supplied is too short and is therefore not shown in the graph of FIG. 2. The second power and the second power supply time will be described in detail in FIG. 7. The time during which the second power is supplied is also not shown in FIGS. 3, 4, and 5 for the same reason.

[0031] When wire feeding is stopped, if the power supplied to the DC motor by control unit 21 is set to 0 (zero), the DC motor continues to operate for a short time (hereinafter referred to as the inertia time) due to the inertia of the DC motor (e.g., the inertia generated when the DC motor rotates). Here, the inertia time is, for example, several hundred milliseconds, which is a time that is sufficiently longer than the second power supply time. In other words, even if the power supplied to the DC motor is set to 0 (zero) during unwinding of welding wire 40, the unwinding of welding wire 40 does not stop instantly but continues for the inertia time due to the inertia of the DC motor. As a result, the unwinding amount of welding wire 40 becomes large and unstable. In order to suppress the occurrence of excessive unwinding of welding wire 40 due to the inertia of the DC motor, control unit 21 supplies the second power to the DC motor for the second power supply time at time t3. With the second power supplied to the DC motor, wire feeder 20 feeds (supplies) welding wire 40 forward to the tip of welding torch 50 for the second power supply time. This allows wire feeder 20 to suppress the occurrence of excess unwinding of welding wire 40 due to inertia of the DC motor. Note that the triangular marks in Figures 2, 3, 4, and 5 indicate the timing at which the second power is applied.

[0032] Next, an "intermittent feed mode 1," which is an example of a welding wire feed mode according to the present embodiment, will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of a welding wire feed mode according to the present embodiment.

[0033] In the graph shown in FIG. 3, the horizontal axis represents time, and the vertical axis represents the wire feed speed at each time.

[0034] In intermittent feed mode 1 shown in the graph of FIG. 3, when welding wire 40 is fed to the tip of welding torch 50, wire feeder 20 feeds welding wire 40 by changing the wire feed speed at least once.

[0035] From time t0 to time t1, the wire feed speed is speed v0. Speed ​​v0 is 0 (zero), which means that no power is supplied to the DC motor of welding wire feeder 22. In other words, from time t0 to time t1, wire feeder 20 is not feeding welding wire 40.

[0036] At time t1, the wire feed speed becomes speed v1, which is greater than speed v0 in the positive direction. Speed ​​v1 is a finite positive speed. At time t1, control unit 21 supplies a third power of positive polarity to the DC motor to change the wire feed speed from speed v0 to speed v1. This enables wire feeder 20 to feed welding wire 40 from welding wire feeder 22 at speed v1. From time t1 to time t4, wire feeder 20 feeds welding wire 40 to the tip of welding torch 50 at speed v1.

[0037] At time t4, control unit 21 changes the wire feed speed from speed v1 to speed v3. Speed ​​v3 is a positive speed greater than or equal to speed v0 (i.e., zero speed) and less than speed v1. Control unit 21 changes the power supplied to the DC motor from third power to fifth power, setting the wire feed speed to speed v3. The fifth power is a positive value smaller than the third power.

[0038] Here, when wire feeder 20 feeds welding wire 40 toward the tip of welding torch 50, if the wire feed speed is changed, there is a possibility that variations in the feed amount will occur due to distortion or bending of welding wire 40 in wire feed path 30. In order to suppress this variation, when control unit 21 slows down the wire feed speed while feeding welding wire 40, it supplies power having a polarity opposite to that of the power currently being supplied to the DC motor for an extremely short time. This allows wire feeder 20 to suppress variations that occur during the feeding of welding wire 40. In other words, at time t4, control unit 21 changes the power supplied to the DC motor from the third power to the fifth power and simultaneously supplies the second power for the second power supply time.

[0039] From time t4 to time t5, wire feeder 20 feeds welding wire 40 to the tip of welding torch 50 at speed v3.

[0040] At time t5, control unit 21 changes the power supplied to the DC motor from the fifth power to the third power and changes the wire feed speed from speed v3 to speed v1. From time t5 to time t6, wire feeder 20 again feeds welding wire 40 at speed v1.

[0041] Here, a series of changes in the wire feed speed from time t1 to time t5 is referred to as speed change 1. In the period from time t5 to time t7, the period from time t7 to time t9, the period from time t9 to time t11, and the period from time t11 to time t13, wire feeder 20 performs the same speed change of welding wire 40 as speed change 1. Note that the number of times that wire feeder 20 repeats speed change 1 is not limited to five times, and may be at least once (including multiple times).

[0042] At time t14, the control unit 21 changes the power supplied to the DC motor from the third power to the fifth power, and sets the wire feed speed to speed v3. Also at time t14, when the control unit changes the power supplied to the DC motor from the third power to the fifth power, it also supplies the second power.

[0043] From time t14 to time t15, wire feeder 20 feeds welding wire 40 at speed v3.

[0044] At time t15, control unit 21 supplies a fourth power, which has the opposite polarity to the fifth power, to the DC motor, and sets the wire feeding speed to speed v2. From time t15 to time t16, wire feeder 20 rewinds welding wire 40 at speed v2. Note that the fourth power may have the opposite polarity to the fifth power, or may simply be a negative value having a polarity opposite to that of the fifth power.

[0045] At time t16, control unit 21 stops supplying power to the DC motor and sets the wire feed speed to speed v0 (i.e., speed 0 (zero)). When control unit 21 stops supplying power to the DC motor at time t16, it supplies second power for a second power supply time. With the second power supplied to the DC motor, wire feeder 20 feeds (supplies) welding wire 40 in the forward direction relative to the tip of welding torch 50 for the second power supply time. This allows wire feeder 20 to suppress the occurrence of excess unwinding of welding wire 40 due to the inertia of the DC motor.

[0046] Next, a "pulse synchronization mode" which is an example of a welding wire feeding mode according to the present embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of a welding wire feeding mode according to the present embodiment.

[0047] The pulse synchronization mode shown in Figure 4 is a mode in which the output of welding power source 10 and changes in the wire feed speed are synchronized. The vertical axis of graph F1 represents the strength of the power output from welding power source 10 (hereinafter referred to as welding power supply output), and the horizontal axis represents time. The vertical axis of graph F2 represents the wire feed speed, and the horizontal axis represents time. The time on the horizontal axis of graphs F1 and F2 represents the same time at the same position.

[0048] From time t0 to time t1, the welding power supply output is output w0 and the power is 0 (zero). At this time, the wire feed speed is v0. Speed ​​v0 is 0 (zero), and no power is supplied to the DC motor of welding wire feeder 22. In other words, from time t0 to time t1, wire feeder 20 is not feeding welding wire 40.

[0049] At time t1, when the welding power supply output becomes output w2, control unit 21 supplies third power to the DC motor and the wire feed speed becomes speed v1. From time t1 to time t20, the welding power supply output is output w2 and the wire feed speed is speed v1.

[0050] At time t20, welding power supply 10 changes the welding power output from output w2 to output w1. Here, output w1 is equal to or less than output w2. At the same time that welding power supply 10 changes the welding power output to output w1, control unit 21 changes the power supplied to the DC motor from third power to fifth power. When changing the power supplied to the DC motor from third power to fifth power, control unit 21 supplies second power to the DC motor for a second power supply time.

[0051] From time t20 to time t21, welding power source 10 sets the welding power output to output w1, and control unit 21 keeps the wire feed speed at speed v3 in accordance with the welding power output.

[0052] At time t21, welding power supply 10 returns the welding power output from output w1 to output w2. At the timing when welding power supply 10 returns the welding power output to output w2, control unit 21 changes the power supplied to the DC motor from the fifth power to the third power, and sets the wire feed speed to speed v1. Here, a series of changes in the welding power output and the wire feed speed from time t1 to time t21 is referred to as speed change 2.

[0053] In the periods from time t21 to time t23, from time t23 to time t25, from time t25 to time t27, and from time t27 to time t29, wire feeder 20 executes a speed change of welding wire 40 similar to speed change 2 in synchronization with the output signal of welding power source 10. Note that the number of times that wire feeder 20 repeats speed change 1 is not limited to five times, and may be at least once multiple times.

[0054] At time t30, the welding power output of welding power supply 10 changes from output w2 to output w0. When the welding power output reaches output w0, control unit 21 changes the power supplied to the DC motor from third power to fourth power, which has the opposite polarity to the third power. The wire feed speed becomes speed v2. From time t30 to time t31, control unit 21 supplies fourth power to the DC motor and rewinds welding wire 40 at speed v2. Note that the fourth power may have the opposite polarity to the third power, or may simply be a negative value having a polarity opposite to that of the third power.

[0055] At time t31, control unit 21 sets the power supplied to the DC motor to 0 (zero), which causes control unit 21 to stop feeding of welding wire 40 to the tip of welding torch 50. When control unit 21 stops feeding of welding wire 40 to the tip of welding torch 50 at time t31, it supplies the second power for a second power supply time.

[0056] In this way, in the pulse synchronization mode, the feed speed of welding wire 40 can be changed by synchronizing control unit 21 of wire feeder 20 with the output of welding power source 10.

[0057] Next, an "intermittent feed mode 2," which is an example of a welding wire feed mode according to the present embodiment, will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of a welding wire feed mode according to the present embodiment.

[0058] Intermittent feeding mode 2 shown in FIG. 5 is a mode in which the wire feeding speed is changed in synchronization with the manual on / off switching of switch 60 by the welding worker or the automatic on / off switching of switch 60 at a time predetermined by the manager of wire feeding device 20.

[0059] In graph F3, the vertical axis represents the magnitude of the switch voltage. The switch voltage is the voltage sent to the control unit 21 when the switch 60 is operated. In graph F3, voltage k0 represents the state when the switch 60 is off, and voltage k1 represents the state when the switch 60 is on. The horizontal axis of graph F3 represents time. In graph F4, the vertical axis represents the wire feed speed, and the horizontal axis represents time. The times in graphs F3 and F4 are the same at the same positions.

[0060] From time t0 to time t1, the switch voltage is voltage k0 and switch 60 is in the OFF state. At this time, the wire feed speed v0 is 0 (zero), and no voltage is applied to the DC motor of welding wire feeder 22. In other words, from time t0 to time t1, wire feeder 20 is not feeding welding wire 40.

[0061] At time t1, when the switch voltage reaches voltage k1 (i.e., when switch 60 is turned on), control unit 21 applies third power to the DC motor, and the wire feed speed becomes speed v1. From time t1 to time t40, switch 60 remains on, and the wire feed speed becomes speed v1.

[0062] At time t40, the switch voltage becomes voltage k0 (i.e., the switch 60 is in an OFF state). When the switch voltage changes from voltage k1 to voltage k0, the control unit changes the power supplied to the DC motor from the third power to the fifth power. When changing the power supplied to the DC motor from the third power to the fifth power, the control unit 21 supplies the second power to the DC motor for a second power supply time.

[0063] From time t40 to time t41, the switch voltage is voltage k0, and the control unit 21 keeps the wire feed speed at speed v3.

[0064] At time t41, switch 60 is turned on again, and the switch voltage changes from voltage k0 to voltage k1. At the timing when the switch voltage becomes voltage k1, control unit 21 changes the power supplied to the DC motor from fifth power to third power and sets the wire feed speed to speed v1. From time t41 to time t42, the switch voltage remains at voltage k1, and the wire feed speed also remains at speed v1.

[0065] When the switch 60 is turned off again at time t42, the switch voltage changes from voltage k1 to voltage k0. The control unit 21 changes the power supplied to the DC motor from the third power to the fifth power in synchronization with the change in the switch voltage. When changing the power applied to the DC motor from the third power to the fifth power, the control unit 21 supplies the second power to the DC motor for a second power supply time. From time t42 to time t43, the wire feed speed is speed v3.

[0066] At time t43, when switch 60 is turned on again, the switch voltage changes from voltage k0 to voltage k1. At the timing when the switch voltage becomes voltage k1, control unit 21 changes the power supplied to the DC motor from fifth power to third power and sets the wire feed speed to speed v1. From time t43 to time t44, the switch voltage remains at voltage k1, and the wire feed speed also remains at speed v1.

[0067] When the switch 60 is turned off again at time t44, the switch voltage changes from voltage k1 to voltage k0. The control unit 21 changes the power supplied to the DC motor from the third power to the fifth power in synchronization with the change in the switch voltage. When changing the power supplied to the DC motor from the third power to the fifth power, the control unit 21 supplies the second power to the DC motor for the second power supply time. From time t44 to time t46, the wire feed speed is speed v3.

[0068] At time t46, control unit 21 receives a signal from switch 60 indicating that the feed of welding wire 40 is to be stopped. The signal indicating that the feed of welding wire 40 is to be stopped is, for example, a signal that switches switch 60 on and off at time intervals shorter than a predetermined time. In the example shown in FIG. 5 , if the time from when switch 60 is turned on at time t45 to when switch 60 is turned off at time t46 is shorter than the time predetermined by the user, switch 60 transmits a signal to control unit 21 to stop the feed of welding wire 40. Note that the above-described example of the signal indicating that the feed of welding wire 40 is to be stopped is merely an example and is not limited thereto.

[0069] At time t46, control unit 21 receives a signal to stop feeding of welding wire 40 and changes the power supplied to the DC motor from the fifth power to the fourth power. The wire feeding speed becomes speed v2. From time t46 to time t47, control unit 21 supplies the fourth power to the DC motor and rewinds welding wire 40 at speed v2.

[0070] At time t47, control unit 21 sets the power supplied to the DC motor to 0 (zero), thereby causing control unit 21 to stop feeding of welding wire 40 to the tip of welding torch 50. When control unit 21 stops feeding of welding wire 40 to the tip of welding torch 50 at time t47, it supplies the second power for a second power supply time.

[0071] As a result, in intermittent feed mode 2, wire feeder 20 can manually or automatically control the feeding of welding wire 40 in synchronization with the switching operation of switch 60. In other words, wire feeder 20 can support flexible and efficient feeding of welding wire 40 in accordance with the content of the welding work performed by the worker.

[0072] When the control unit 21 supplies the second power to the DC motor, the positive or negative polarity (for example, the third or fourth power in this embodiment) that was supplied to the DC motor immediately before is defined as the first power.

[0073] Next, an example of control of current flowing through a DC motor according to a conventional technique will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of control of current flowing through a DC motor according to a conventional technique.

[0074] The vertical axis of the graph shown in Fig. 6 represents the value of the current flowing through the DC motor (hereinafter referred to as the motor current), and the horizontal axis of the graph shown in Fig. 6 represents time.

[0075] Current A0 represents a state in which the motor current is 0. In the graph shown in Figure 6, currents equal to or greater than A0 are positive values, and currents less than A0 are negative values. As the value moves in the direction of the arrow on the vertical axis, the motor current value increases in the positive direction. Below, the vertical and horizontal axes of the graphs shown in Figure 7 are the same as those in the graph of Figure 6, and similar values ​​are denoted with the same symbols.

[0076] The motor current is A1 from time TI0 to time TI1. The motor current value fluctuates due to control ripples that occur when the DC motor speed is controlled by PWM control.

[0077] At time TI1, the motor current becomes current A0 (that is, current 0 (zero)), and thereafter remains constant at current A0.

[0078] Next, an example of control of the current flowing through the DC motor according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of control of the current flowing through the DC motor according to this embodiment.

[0079] At time TI1, under the control of the control unit 21, the motor current changes from current A1 to current A2 over a delay time PE. Here, the power supplied to the DC motor when the current is A2 is the second power, and the delay time PE is the second power supply time. The delay time PE is, for example, several tens of milliseconds. Note that the length of the delay time PE is not limited to several tens of milliseconds. After the motor current becomes current A2 under the control of the control unit 21, it quickly becomes current A0 (i.e., 0 (zero)) at time TI2.

[0080] The delay time PE, which is the second power supply time, is not limited to a fixed value and may be a variable value. For example, the delay time PE varies depending on the rotation speed of the DC motor immediately before the second power is supplied to the DC motor. For example, the delay time PE is longer when the rotation speed of the DC motor is fast and shorter when the rotation speed is slow.

[0081] Furthermore, for example, the delay time PE varies depending on the state of the rotation speed and current of the DC motor immediately before the second power is supplied to the DC motor. For example, the delay time PE may be set by the control unit 21 by combining the fact that the delay time PE is long when the rotation speed of the DC motor is fast and short when the rotation speed is slow, and the fact that the delay time PE is long when the current of the DC motor is low and short when the current is high.

[0082] As described above, a welding apparatus (e.g., welding system 100) according to this embodiment is a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, and includes a wire feeder (e.g., wire feeder 20) that feeds a welding wire (e.g., welding wire 40) to a welding torch (e.g., welding torch 50) or unwinds the welding wire from the welding torch by rotating a DC motor, and a control unit (e.g., control unit 21) that supplies power to the DC motor to drive the DC motor. After the control unit supplies a first power of either positive or negative polarity to the DC motor to feed or unwind the welding wire, the control unit supplies a second power of opposite polarity to the first power to the DC motor when the DC motor is to be stopped or the welding wire feed speed is to be slowed down.

[0083] As a result, the welding device according to this embodiment can suppress variations in the welding wire protrusion amount that occur when the DC motor is stopped (i.e., when the feeding of the welding wire is stopped) or variations in the feeding amount to the welding torch that occur when the feeding speed of the welding wire is slowed down. As a result, the welding device can stably feed the welding wire, improving the workability and quality of welding.

[0084] Furthermore, the control unit of the welding device according to this embodiment supplies the second power to the DC motor for a second power supply time that is shorter than the time for which the first power is supplied to the DC motor. This allows the welding device to supply the second power, which has the opposite polarity to the first power, for a very short time. The welding device can use the second power to reduce variations in the welding wire protrusion amount that occur when the DC motor is stopped (i.e., when the feeding of the welding wire is stopped) or variations in the amount of welding wire fed to the welding torch that occur when the feeding speed of the welding wire is slowed. This allows the welding device to stably feed the welding wire and improve the workability and quality of welding.

[0085] Furthermore, the second power of the welding device according to this embodiment has a polarity opposite to that of the power previously supplied by the control unit, which allows the welding device to suppress the effects of inertia generated in the DC motor, ensure stable feeding of the welding wire, and improve the workability and quality of welding.

[0086] Furthermore, the control unit of the welding device according to this embodiment supplies a third power of positive polarity to the DC motor to feed the welding wire, and after feeding the welding wire, supplies a fourth power of negative polarity to the DC motor to rewind the welding wire. After rewinding the welding wire, the control unit supplies a second power to the DC motor for a second power supply time when stopping the DC motor. This allows the welding device to continuously feed the welding wire and finally stop the DC motor to rewind the welding wire to an appropriate length when ending the welding wire feeding. This allows the welding device to assist the operator in starting welding with an appropriate welding wire protrusion.

[0087] Furthermore, the control unit of the welding device according to this embodiment supplies the second power to the DC motor for the first time when changing the power supplied to the DC motor from the third power, which is positive, to the fifth power, which is positive and less than the third power, thereby enabling the welding device to suppress variations in the feed amount that occur when changing the feed speed of the welding wire.

[0088] Furthermore, the control unit of the welding device according to this embodiment executes at least once a first control in which the power supplied to the DC motor is changed from the third power to the fifth power and then changed back to the third power, thereby enabling the welding device to change the welding wire feed speed when feeding the welding wire to the welding torch and feed the welding wire in a manner appropriate for the welding situation.

[0089] Furthermore, the control unit of the welding device according to this embodiment supplies the third power or the fifth power to the DC motor to feed the welding wire, then supplies the fourth power, which has negative polarity, to the DC motor to rewind the welding wire, and after rewinding the welding wire, supplies the second power to the DC motor for the second power supply time when stopping the DC motor. This allows the welding device to suppress the effects of inertia that occur in the DC motor when stopping the feeding of the welding wire, thereby enabling stable feeding of the welding wire and improving the workability and quality of welding.

[0090] Furthermore, the control unit of the welding apparatus according to this embodiment supplies a third power to the DC motor when the operator turns on a switch (e.g., switch 60) related to welding wire feeding of the wire feeder, and changes the power supplied to the DC motor to a fifth power when the operator turns off the switch. When the operator turns on the switch after an inertia time longer than the second power supply time has elapsed since turning off the switch and then turns it off again, the control unit supplies a first power to the DC motor to rewind the welding wire, and when the DC motor is stopped after rewinding the welding wire, the control unit supplies a second power to the DC motor for the second power supply time. This allows the welding apparatus to change the welding wire feed rate in response to the on / off switching of the switch. The welding apparatus can support flexible welding wire feeding according to the welding work content or situation. Furthermore, the welding apparatus can suppress the influence of inertia generated in the DC motor when welding wire feeding is stopped, thereby stably feeding the welding wire and improving welding workability and quality.

[0091] Furthermore, the control unit of the welding device according to this embodiment changes the power supplied to the DC motor in synchronization with the pulse signal output from the welding power source during pulse welding, which alternates between a first welding current and a second welding current smaller than the first welding current. This allows the welding device to feed the welding wire based on the pulse signal output from the welding power source during pulse welding, thereby supporting flexible and efficient welding wire feeding.

[0092] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, alterations, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also fall within the technical scope of the present disclosure. Furthermore, the components in the above-described embodiments may be combined in any manner without departing from the spirit of the invention. [Industrial Applicability]

[0093] The technology disclosed herein is useful as a welding device and a welding method that stably feeds a welding wire and improves the workability and quality of welding. [Explanation of symbols]

[0094] 10 Welding power source 20 Wire feeder 21 Control section 22 Welding wire feeder 30 Wire feeding path 40 welding wire 50 Welding Torch 60 Switch 70 Base Cable 100 Welding System PL welding points t0,t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16,t20,t21,t22,t23, t24,t25,t26,t27,t28,t29,t30,t31,t40,t41,t42,t43,t44,t45,t46,t47,TI0,TI1,TI2 moment v0, v1, v2, v3 speed w0,w1,w2 output k0,k1 electric pressure F1,F2,F3,F4 グラフ Currents at A0, A1, and A2

Claims

1. In the non-consumable electrode arc welding apparatus and the consumable electrode arc welding apparatus, a wire feeder is provided which feeds a welding wire to a welding torch or unwinds the welding wire from the welding torch by rotation of a DC motor; a control unit that supplies power to the DC motor to drive the DC motor, the control unit supplies a first power having either a positive polarity or a negative polarity to the DC motor to feed or rewind the welding wire, and then, when stopping the DC motor or slowing down the feeding speed of the welding wire, supplies a second power having a polarity opposite to that of the first power to the DC motor; the control unit supplies the second power to the DC motor for a second power supply time that is shorter than a time for which the first power is supplied to the DC motor; the control unit supplies the second power to the DC motor for the second power supply time when changing the power supplied to the DC motor from a third power having a positive polarity to a fifth power having a positive polarity smaller than the third power; the control unit executes at least once a first control in which the power supplied to the DC motor is changed from the third power to the fifth power and then changed back to the third power; the control unit supplies the third power or the fifth power to the DC motor to feed the welding wire, then supplies a fourth power having a negative polarity to the DC motor to rewind the welding wire, and after rewinding the welding wire, supplies the second power to the DC motor for the second power supply time when stopping the DC motor. Welding equipment.

2. In a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, a wire feeding device that feeds welding wire to a welding torch or rewinds the welding wire from the welding torch by rotation of a DC motor; a control unit that supplies power to the DC motor to drive the DC motor, the control unit supplies a first power having either a positive polarity or a negative polarity to the DC motor to feed or rewind the welding wire, and then, when stopping the DC motor or slowing down the feeding speed of the welding wire, supplies a second power having a polarity opposite to that of the first power to the DC motor; the control unit supplies the second power to the DC motor for a second power supply time that is shorter than a time for which the first power is supplied to the DC motor; the control unit supplies the second power to the DC motor for the second power supply time when changing the power supplied to the DC motor from a third power having a positive polarity to a fifth power having a positive polarity smaller than the third power; the control unit supplies the third power to the DC motor when an operator turns on a switch related to feeding of the welding wire of the wire feeder, and changes the power supplied to the DC motor to the fifth power when the operator turns off the switch; When the operator turns on the switch after an inertia time longer than the second power supply time has elapsed since turning off the switch and then turns off the switch again, the first power is supplied to the DC motor to rewind the welding wire, and after rewinding the welding wire, the second power is supplied to the DC motor for the second power supply time when the DC motor is stopped. Welding equipment.

3. In a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, a wire feeding device that feeds welding wire to a welding torch or rewinds the welding wire from the welding torch by rotation of a DC motor; a control unit that supplies power to the DC motor to drive the DC motor, the control unit supplies a first power having either a positive polarity or a negative polarity to the DC motor to feed or rewind the welding wire, and then, when stopping the DC motor or slowing down the feeding speed of the welding wire, supplies a second power having a polarity opposite to that of the first power to the DC motor; the control unit changes the power supplied to the DC motor in synchronization with a pulse signal output from a welding power source during pulse welding in which a first welding current and a second welding current smaller than the first welding current are repeated. Welding equipment.

4. the control unit supplies the second power to the DC motor for a second power supply time that is shorter than the time for which the first power is supplied to the DC motor.

4. The welding device of claim 3.

5. The second power has a polarity opposite to that of the first power or the power previously supplied constantly by the control unit. The welding device according to any one of claims 1 to 4.

6. The control unit supplying a third power having a positive polarity to the DC motor to feed the welding wire; after feeding the welding wire, supplying a fourth power having a negative polarity to the DC motor to rewind the welding wire; supplying the second power to the DC motor for the second power supply period when the DC motor is stopped after the welding wire is rewound; The welding device according to claim 1, claim 2 or claim 4.

7. the control unit supplies the second power to the DC motor for the second power supply time when changing the power supplied to the DC motor from a third power having a positive polarity to a fifth power having a positive polarity smaller than the third power.

4. The welding device of claim 3.

8. the control unit executes a first control at least once to change the power supplied to the DC motor from the third power to the fifth power and then change the power back to the third power.

8. The welding device according to claim 2 or 7.

9. the control unit supplies the third power or the fifth power to the DC motor to feed the welding wire, then supplies a fourth power having a negative polarity to the DC motor to rewind the welding wire, and after rewinding the welding wire, supplies the second power to the DC motor for the second power supply time when stopping the DC motor.

9. The welding apparatus of claim 8.

10. the control unit supplies the third power to the DC motor when an operator turns on a switch related to feeding of the welding wire of the wire feeder, and changes the power supplied to the DC motor to the fifth power when the operator turns off the switch; When the operator turns on the switch after an inertia time longer than the second power supply time has elapsed since turning off the switch and then turns off the switch again, the first power is supplied to the DC motor to rewind the welding wire, and after rewinding the welding wire, the second power is supplied to the DC motor for the second power supply time when the DC motor is stopped.

8. The welding apparatus of claim 7.

11. In pulse welding in which a first welding current and a second welding current smaller than the first welding current are repeated, the control unit synchronizes with a pulse signal output from a welding power source and changes the power supplied to the DC motor.

3. The welding device according to claim 1 or 2.

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