WO2024116477A1

WO2024116477A1 - Welding device and welding method

Info

Publication number: WO2024116477A1
Application number: PCT/JP2023/028997
Authority: WO
Inventors: 紀典本宮; 昌良植田
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2022-11-30
Filing date: 2023-08-08
Publication date: 2024-06-06

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

Welding equipment and welding method

This disclosure relates to a welding device and a welding method.

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 feeding device. In the semi-automatic welding method, prior to the start of welding, the welding wire is run in reverse and the welding wire protruding from the welding tip of the welding torch is pulled toward the welding tip until its tip reaches a reference position, and then feeding of the welding wire begins. The semi-automatic welding method is characterized in that the feeding of the welding wire is temporarily stopped when the amount of welding wire protruding from the welding tip reaches a dimension suitable for starting welding.

JP 2000-202629 A

The purpose of this disclosure is to stably feed welding wire and improve the workability and quality of welding.

The present disclosure provides a welding device that is a non-consumable electrode arc welding device and a consumable electrode arc welding device, and includes a wire feeder that feeds a welding wire to a welding torch or rewinds the welding wire from the welding torch by rotating 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 of either positive or negative polarity to the DC motor to feed or rewind the welding wire, and then supplies a second power of opposite polarity to the first power to the DC motor when the DC motor is stopped or the feeding speed of the welding wire is slowed down.

The present disclosure also provides a welding method performed by a welding system in a non-consumable electrode arc welding device and a consumable electrode arc welding device, the welding system including a wire feeder that feeds or rewinds a welding wire to a welding torch by rotating a DC motor, and a control unit that supplies power to the DC motor to drive the DC motor, the welding method including supplying a first power of either positive or negative polarity to the DC motor to feed or rewind the welding wire, and then supplying a second power of a different polarity to the first power to the DC motor when the DC motor is stopped or the feeding speed of the welding wire is reduced.

These comprehensive or specific aspects may be realized as a system, device, method, integrated circuit, computer program, or recording medium, or as any combination of a system, device, method, integrated circuit, computer program, and recording medium.

According to the present disclosure, the welding wire can be fed stably, improving the workability and quality of welding.

A configuration diagram of a welding system according to the present embodiment. FIG. 1 is a diagram showing an example of a feeding mode of a welding wire according to an embodiment of the present invention; FIG. 1 is a diagram showing an example of a feeding mode of a welding wire according to an embodiment of the present invention; FIG. 1 is a diagram showing an example of a feeding mode of a welding wire according to an embodiment of the present invention; FIG. 1 is a diagram showing an example of a feeding mode of a welding wire according to an embodiment of the present invention; FIG. 1 is a diagram showing an example of control of a current flowing through a DC motor according to a conventional technique. FIG. 1 is a diagram showing an example of control of a current flowing through a DC motor according to an embodiment of the present invention;

(Background to the present embodiment)
Semi-automatic TIG (Tungsten Inert Gas) welding is one type of arc welding in which a feeder feeds a welding wire through a feed path to a welding point to perform welding. In semi-automatic TIG welding, it is important for improving the workability and quality of welding that the welding wire protrusion amount before welding is appropriate and that the welding wire is stably fed during welding.

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

Below, with appropriate reference to the drawings, a detailed description will be given of an embodiment specifically disclosing the welding apparatus and 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 duplicate descriptions of substantially identical configurations may be omitted. This is to avoid the following description becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the attached 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.

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.

The welding system 100 according to this embodiment includes a welding power source 10, a wire feeder 20, a welding torch 50, and a switch 60.

The welding power supply 10, which is an example of a power supply, 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 supply 10 is, for example, a dual-purpose AC/DC power supply that can supply both AC and DC current. Note that the welding power supply 10 is not limited to being a dual-purpose AC/DC source, and may be capable of supplying only DC or only AC. The welding power supply 10 outputs, for example, approximately 200 A of DC or AC current as an example of the necessary power supply. Note that the current value output by the welding power supply 10 is only an example and is not limited to 200 A.

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

The control unit 21 functions as a controller that manages the overall operation of the wire feeder 20. The control unit 21 may be a semiconductor chip in which at least one of electronic devices such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), a GPU (Graphical Processing Unit), and an FPGA (Field Programmable Gate Array) is mounted on a control board (see above). The wire feeder 20 has a memory, which is not shown in FIG. 1, and the control unit 21 uses the RAM (Random Access Memory) of the memory (not shown) during operation, and temporarily stores data generated or acquired by the control unit 21 in the RAM of the memory. 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. The control unit 21 also controls the power supplied to drive the DC motor of the welding wire feeder 22 based on the pulse synchronization signal output from the welding power source 10 in the pulse synchronization mode (see FIG. 4).

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 electromagnetic field type DC motor. Note that the welding wire feeder 22 is not limited to a DC motor and may also have an AC (Alternating Current) motor that is driven by an AC 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.

While welding is being performed, the welding wire feeder 22 uses a DC motor to feed (supply) the welding wire 40 forward toward the tip of the welding torch 50, or to feed (retract) the welding wire 40 backward from the tip of the welding torch 50.

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

The welding wire 40 is, for example, a filler wire such as stainless steel. Note that the welding wire 40 is not limited to a filler wire such as stainless steel. The welding wire 40 is fed from the wire feeder 20 through the wire feed path 30 to the tip of the welding torch 50.

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

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

The base material cable 70 is a welding cable that connects the terminal of the welding power source 10 to the welding point PL.

Next, a "continuous feed mode" which is an example of a welding wire feed mode according to this embodiment will be described with reference to FIG. 2. FIG. 2 is a diagram showing an example of a welding wire feed mode according to this embodiment.

In the graph shown in FIG. 2, the horizontal axis represents time, and the vertical axis represents the feed speed of the welding wire 40 at each time. Hereinafter, the feed speed of the welding wire 40 will be referred to as the wire feed speed.

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

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. 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.

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

At time t3, the control unit 21 stops the supply of the fourth power to the DC motor, and the wire feed speed becomes v0 again. When the control unit 21 stops the supply of the fourth power to the DC motor, it 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. The second power supply time is not limited to a fixed value, and may change, 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. Since the time in FIG. 2 is on the order of several seconds, the time for supplying the second power is too short and is not shown in the graph in FIG. 2. Note that the second power and the second power supply time will be described in detail in FIG. 7. The time for which the second power is supplied is also not shown in FIG. 3, FIG. 4, and FIG. 5 for the same reason.

When the wire feed is stopped, if the power supplied to the DC motor by the control unit 21 is set to 0 (zero), the DC motor continues to move for a short time (hereinafter referred to as the inertia time) due to the inertia of the DC motor (for example, the inertia generated when the DC motor rotates). Here, the inertia time is, for example, several hundred milliseconds, which 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) when the welding wire 40 is being rewound, the rewinding of the welding wire 40 does not stop instantly and continues for the inertia time due to the inertia of the DC motor. Therefore, the amount of rewinding of the welding wire 40 becomes large and unstable. In order to suppress the occurrence of excess rewinding of the welding wire 40 due to the inertia of the DC motor, the 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, the wire feeder 20 feeds (supplies) the welding wire 40 forward to the tip of the welding torch 50 for the second power supply time. This allows the wire feeder 20 to suppress the occurrence of excess rewinding of the welding wire 40 due to the inertia of the DC motor. Note that the triangular marks in Figures 2, 3, 4, and 5 indicate the timing when the second power is applied.

Next, with reference to Figure 3, we will explain "intermittent feed mode 1," which is an example of a welding wire feed mode according to this embodiment. Figure 3 is a diagram showing an example of a welding wire feed mode according to this embodiment.

In the graph shown in Figure 3, the horizontal axis represents time and the vertical axis represents the wire feed speed at each time.

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

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.

At time t4, the 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. 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. The fifth power is a positive value less than the third power.

When the wire feeder 20 feeds the welding wire 40 toward the tip of the 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 the welding wire 40 in the wire feed path 30. In order to suppress this variation, when the control unit 21 slows down the wire feed speed while feeding the welding wire 40, it supplies power having the opposite polarity to the power currently being supplied to the DC motor for an extremely short time. This allows the wire feeder 20 to suppress variations that occur while feeding the welding wire 40. In other words, at time t4, the 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.

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

At time t5, the 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, the wire feeder 20 again feeds the welding wire 40 at speed v1.

Here, the 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, the wire feeder 20 executes a speed change of the welding wire 40 similar to speed change 1. Note that the number of times that the wire feeder 20 repeats speed change 1 is not limited to five times, and may be at least once (including multiple times).

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, the control unit simultaneously supplies the second power when changing the power supplied to the DC motor from the third power to the fifth power.

From time t14 to time t15, the wire feeder 20 feeds the welding wire 40 at a speed v3.

At time t15, the control unit 21 supplies the DC motor with a fourth power, which has the opposite polarity to the fifth power, and sets the wire feed speed to speed v2. From time t15 to time t16, the wire feeder 20 rewinds the welding wire 40 at speed v2. The fourth power may have the opposite polarity to the fifth power, or may simply be a negative value with a different polarity from the fifth power.

At time t16, the 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 the control unit 21 stops the supply of power to the DC motor at time t16, it supplies the second power for the second power supply time. As a result of the second power being supplied to the DC motor, the wire feeder 20 feeds (supplies) the welding wire 40 in the forward direction to the tip of the welding torch 50 for the second power supply time. This allows the wire feeder 20 to suppress the occurrence of excess rewinding of the welding wire 40 due to the inertia of the DC motor.

Next, the "pulse synchronous mode", which is an example of a welding wire feed mode according to this embodiment, will be described with reference to FIG. 4. FIG. 4 is a diagram showing an example of a welding wire feed mode according to this embodiment.

The pulse synchronization mode shown in FIG. 4 is a mode in which the output of the welding power supply 10 and changes in the wire feed speed are synchronized. The vertical axis of graph F1 represents the strength of the power output from the welding power supply 10 (hereinafter referred to as the 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 times on the horizontal axes of graphs F1 and F2 represent the same times at the same positions.

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 being supplied to the DC motor of the welding wire feeder 22. In other words, from time t0 to time t1, the wire feeder 20 is not feeding the welding wire 40.

At time t1, when the welding power supply output becomes output w2, the control unit 21 supplies a 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 becomes speed v1.

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

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

At time t21, the welding power supply 10 changes the welding power output back from output w1 to output w2. At the timing when the welding power supply 10 changes the welding power output back to output w2, the 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, the series of changes in the welding power output and wire feed speed from time t1 to time t21 is referred to as speed change 2.

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, the wire feeder 20 executes a speed change of the welding wire 40 similar to speed change 2 in synchronization with the output signal of the welding power source 10. Note that the number of times that the wire feeder 20 repeats speed change 1 is not limited to five times, and may be at least once multiple times.

At time t30, the welding power output of the welding power source 10 changes from output w2 to output w0. When the welding power output becomes output w0, the control unit 21 changes the power supplied to the DC motor from the third power to the fourth power, which is the opposite polarity of the third power. The wire feed speed becomes speed v2. From time t30 to time t31, the control unit 21 supplies the fourth power to the DC motor and rewinds the welding wire 40 at speed v2. The fourth power may be the opposite polarity of the third power, or may simply be a negative value with a different polarity from the third power.

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

In this way, in the pulse synchronization mode, the control unit 21 of the wire feeder 20 can be synchronized with the output of the welding power source 10 to change the feed speed of the welding wire 40.

Next, with reference to FIG. 5, an example of a welding wire feeding mode according to this embodiment, "intermittent feeding mode 2", will be described. FIG. 5 is a diagram showing an example of a welding wire feeding mode according to this embodiment.

Intermittent feed mode 2 shown in FIG. 5 is a mode in which the wire feed speed is changed in synchronization with the switch 60 being manually turned on/off by the worker performing the welding, or the switch 60 being automatically turned on/off at a time preset by the manager of the wire feeder 20.

In graph F3, the vertical axis represents the magnitude of the switch voltage. The switch voltage is the voltage sent to control unit 21 when switch 60 is operated. In graph F3, voltage k0 represents the state when switch 60 is off, and voltage k1 represents the state when 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. Graphs F3 and F4 represent the same time at the same position.

From time t0 to time t1, the switch voltage is k0 and the 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 the welding wire feeder 22. In other words, from time t0 to time t1, the wire feeder 20 is not feeding the welding wire 40.

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

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 the second power supply time.

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.

At time t41, when the switch 60 is turned on again, the switch voltage changes from voltage k0 to voltage k1. When the switch voltage becomes voltage k1, the 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. From time t41 to time t42, the switch voltage remains at voltage k1, and the wire feed speed also remains at speed v1.

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 the power applied to the DC motor is changed 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 t42 to time t43, the wire feed speed is speed v3.

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 the fifth power to the 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.

When the switch 60 turns 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.

At time t46, the control unit 21 obtains a signal from the switch 60 to stop feeding the welding wire 40. The signal to stop feeding the welding wire 40 is, for example, a signal that switches the switch 60 on and off at time intervals shorter than a predetermined time. In the example of FIG. 5, if the time from when the switch 60 is turned on at time t45 to when the switch 60 is turned off at time t46 is shorter than a time predetermined by the user, the switch 60 transmits a signal to the control unit 21 to stop feeding the welding wire 40. Note that the above-mentioned example of the signal to stop feeding the welding wire 40 is one example and is not limited to this.

At time t46, the control unit 21 receives a signal to stop feeding the 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, the control unit 21 supplies the fourth power to the DC motor and rewinds the welding wire 40 at speed v2.

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

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

When the control unit 21 supplies the second power to the DC motor, the positive or negative polarity (e.g., the third or fourth power in this embodiment) that was previously supplied to the DC motor is defined as the first power.

Next, an example of controlling the current flowing through a DC motor according to the conventional technology will be described with reference to FIG. 6. FIG. 6 is a diagram showing an example of controlling the current flowing through a DC motor according to the conventional technology.

The vertical axis of the graph shown in Figure 6 represents the value of the current flowing through the DC motor (hereinafter referred to as the motor current). The horizontal axis of the graph shown in Figure 6 represents time.

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 indicate positive values, and currents less than A0 indicate 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 given the same symbols.

From time TI0 to time TI1, the motor current is A1. The motor current value fluctuates due to the control ripple that occurs when the DC motor's speed is controlled by PWM control.

At time TI1, the motor current becomes current A0 (i.e., current 0 (zero)), and then becomes a constant value at current A0.

Next, an example of controlling 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 controlling the current flowing through the DC motor according to this embodiment.

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.

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 changes 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.

Furthermore, for example, the delay time PE varies depending on the rotation speed of the DC motor and the state of the 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 following: when the rotation speed of the DC motor is fast, the delay time PE is long, and when the rotation speed of the DC motor is slow, the delay time PE is short; and when the current of the DC motor is low, the delay time PE is long, and when the current of the DC motor is high, the delay time PE is short.

As described above, the welding device (e.g., welding system 100) according to this embodiment is a non-consumable electrode arc welding device and a consumable electrode arc welding device, 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 rewinds 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. The control unit supplies a first power, which is either positive or negative polarity, to the DC motor to feed or rewind the welding wire, and then supplies a second power having the opposite polarity to the first power to the DC motor when the DC motor is stopped or the welding wire feed speed is slowed down.

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

The control unit of the welding device according to this embodiment also supplies a 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 a second power that is 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 amount of welding wire protrusion that occur when the DC motor is stopped (i.e., the feeding of the welding wire is stopped) or variations in the amount of wire fed to the welding torch that occur when the feeding speed of the welding wire is slowed down. This allows the welding device to stably feed the welding wire, improving the workability and quality of welding.

In addition, the second power of the welding device according to this embodiment has the opposite polarity to the power that was previously supplied constantly by the control unit. This allows the welding device to suppress the effects of inertia generated in the DC motor, and to stably feed the welding wire, improving the workability and quality of welding.

The control unit of the welding device according to this embodiment also 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 to rewind the welding wire to an appropriate length when finally stopping the DC motor and ending the feeding of the welding wire. This allows the welding device to assist the operator in starting welding with an appropriate welding wire protrusion amount.

In addition, when the control unit of the welding device according to this embodiment changes the power supplied to the DC motor from the third power, which is positive, to the fifth power, which is less positive than the third power, the control unit supplies the second power to the DC motor for the first time. This allows the welding device to suppress variations in the feed amount that occur when changing the feed speed of the welding wire.

The control unit of the welding device according to this embodiment also executes the first control at least once, which changes the power supplied to the DC motor from the third power to the fifth power and then back to the third power. This allows the welding device to change the welding wire feed speed when feeding the welding wire to the welding torch, thereby feeding the welding wire in a manner appropriate to the welding conditions.

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 is 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 the feeding of the welding wire is stopped, and allows the welding wire to be fed stably, improving the workability and quality of welding.

The control unit of the welding device according to this embodiment supplies a third power to the DC motor when the worker turns on a switch (e.g., switch 60) related to the feeding of the welding wire of the wire feeder, and changes the power supplied to the DC motor to a fifth power when the worker turns off the switch. When the worker 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 control unit supplies a first power to the DC motor to rewind the welding wire, and after rewinding the welding wire, supplies a second power to the DC motor for the second power supply time when stopping the DC motor. This allows the welding device to change the amount of welding wire fed in response to the on/off switching of the switch. The welding device can support flexible feeding of the welding wire according to the welding work content or situation. The welding device can also suppress the effect of inertia generated in the DC motor when the feeding of the welding wire is stopped, and can stably feed the welding wire and improve the workability and quality of welding.

The control unit of the welding device according to this embodiment also 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, supporting flexible and efficient welding wire feeding.

　Although the embodiments have been described above with reference to the attached 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, amendments, 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 as long as it does not deviate from the spirit of the invention.

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

REFERENCE SIGNS LIST 10 Welding power source 20 Wire feeder 21 Control unit 22 Welding wire feeder 30 Wire feed path 40 Welding wire 50 Welding torch 60 Switch 70 Base metal cable 100 Welding system PL Welding point 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 Time v0, v1, v2, v3 Speed w0, w1, w2 Output k0, k1 Voltage F1, F2, F3, F4 Graph A0, A1, A2 Current

Claims

In the non-consumable electrode type arc welding apparatus and the consumable electrode type arc welding apparatus, a wire feeder 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 feed speed of the welding wire, supplies a second power having a polarity opposite to that of the first power to the DC motor.
Welding equipment.
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.
2. The welding apparatus of claim 1.
The second power has a polarity opposite to that of the first power or the power previously supplied constantly by the control unit.
2. The welding apparatus of claim 1.
The control unit is
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;
3. The welding apparatus of claim 2.
the control unit, 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, supplies the second power to the DC motor for the second power supply time.
3. The welding apparatus of claim 2.
The control unit executes a first control at least once in which the power supplied to the DC motor is changed from the third power to the fifth power and then returned to the third power.
6. The welding apparatus of claim 5.
the control unit supplies the third power or the fifth power to the DC motor to feed the welding wire, and 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.
7. The welding apparatus of claim 6.
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 the welding wire is rewinded, the second power is supplied to the DC motor for the second power supply time when the DC motor is stopped.
6. The welding apparatus of claim 5.
the control unit changes the power supplied to the DC motor in synchronization with a pulse signal output from a welding power source in pulse welding in which a first welding current and a second welding current smaller than the first welding current are repeated.
A welding device according to any one of claims 1 to 8.
A welding method performed by a welding system in a non-consumable electrode arc welding apparatus and a consumable electrode arc welding apparatus, the welding system including a wire feeder that feeds or rewinds a welding wire to a welding torch by rotation of a DC motor, and a control unit that supplies power to the DC motor to drive the DC motor,
a first power having either a positive polarity or a negative polarity is supplied to the DC motor to feed or rewind the welding wire, and then, when the DC motor is stopped or the feed speed of the welding wire is reduced, a second power having a polarity different from that of the first power is supplied to the DC motor.
Welding method.