Patent Description:
A welding device that is disclosed in PTL <NUM> includes: a high frequency voltage application unit that applies a high frequency voltage between a tungsten electrode and a welding target; a current detection unit that detects a welding current; and a controller that acquires, at a time of performing a start operation for starting applying of the high frequency voltage to the high frequency voltage application unit, a delay time from starting of the start operation to the detection of the welding current by the current detection unit, and performs a processing at an abnormal time such as allowing a warning device to output warning when the delay time is more than or equal to a predetermined time.

However, in above-mentioned PTL <NUM>, even when the delay time at the time of performing the start operation exceeds the predetermined time only one time, the controller performs the processing at an abnormal time. Accordingly, the processing at an abnormal time is likely to be performed due to a temporary factor other than wear of a tungsten electrode or the formation of smear on the tungsten electrode.

The present disclosure has been made in view of the above-mentioned circumstance, and it is an object of the present disclosure to provide a welding device that can suppress the performing of the processing at an abnormal time due to a temporary factor other than wear of a tungsten electrode or the formation of smear on the tungsten electrode.

According to an aspect of the present invention, there is provided a welding device according to claim <NUM>.

According to this aspect, the controller determines whether or not the processing at an abnormal time is performed based on the delay times at the plurality of previous points of time at which the start operation is performed. Accordingly, compared with the case where whether or not the processing at an abnormal time is performed is determined based on the delay time at the time of performing the start operation one time as described in PTL <NUM>, the processing at an abnormal time is minimally performed due to a temporary factor other than the wear of the tungsten electrode and the formation of smear on the tungsten electrode.

According to this disclosure, the welding device can suppress the performing of the processing at an abnormal time due to a temporary factor other than wear of a tungsten electrode or the formation of smear on the tungsten electrode.

<FIG> illustrates welding device <NUM> according to an example of the present disclosure. Welding device <NUM> performs tungsten inert gas (TIG) welding by generating arc A between tungsten electrode <NUM> mounted on welding torch <NUM> and base material <NUM> that forms a welding target. Specifically, welding device <NUM> includes input circuit unit <NUM>, gas control device <NUM>, high frequency voltage application unit <NUM>, welding output circuit unit <NUM>, current detection unit <NUM>, display data storage unit <NUM>, display unit <NUM> that forms an output unit, controller <NUM>, and delay time storage unit <NUM>.

Input circuit unit <NUM> outputs welding instruction signal S1 indicating an ON/OFF state of switch <NUM> mounted on welding torch <NUM>.

When controller <NUM> starts outputting gas supply signal S2 to gas control device <NUM>, gas control device <NUM> makes welding torch <NUM> start jetting of a shielding gas to base material <NUM>. As the shield gas, for example, an argon gas or the like is used. Gas control device <NUM> is connected to welding torch <NUM> by way of gas hose <NUM>.

When controller <NUM> outputs high frequency voltage application signal S3 to high frequency voltage application unit <NUM>, high frequency voltage application unit <NUM> applies a high frequency high voltage between tungsten electrode <NUM> and base material <NUM>.

Welding output circuit unit <NUM> controls a welding voltage and a welding current based on welding control signal S4 output from controller <NUM>. Welding output circuit unit <NUM> is electrically connected to welding torch <NUM> via welding output cable <NUM>.

Current detection unit <NUM> detects a welding current more than or equal to a predetermined current threshold. As a specific operation, current detection unit <NUM> outputs current detection signal S5 when a welding current exceeds the current threshold.

Display data storage unit <NUM> stores image data of an image to be output and displayed on display unit <NUM>. The image data to be stored includes image data of first to fourth warning images as an output. The first warning image displays a message that "The electrode is getting smeared. ", the second warning image displays a message that "The electrode is worn so that there is a possibility that the generation of an arc does not start. ", and the third warning image displays a message that "The electrode is largely worn and smeared. Polishing of the electrode is recommended". The fourth warning image displays a message that "Please polish or exchange the electrode.

Display unit <NUM> is, for example, a display. Display unit <NUM> outputs and displays an image based on image data stored in display data storage unit <NUM>.

Controller <NUM> selectively performs a control between a control in an AC output mode where welding control signal S4 is outputted to welding output circuit unit <NUM> in such a manner that a welding voltage and a welding current become an alternating current voltage and an alternating current respectively, and a control in a DC output mode where welding control signal S4 is output to welding output circuit unit <NUM> in such a manner that a welding voltage and a welding current become a direct current voltage and a direct current respectively.

Controller <NUM> starts outputting of gas supply signal S2 when switch <NUM> of welding torch <NUM> is switched from an OFF state to an ON state so that welding instruction signal S1 output from input circuit unit <NUM> is switched from a signal indicating an OFF state to a signal indicating an ON state.

In addition, when predetermined preflow time Tp has elapsed from a point of time that outputting of gas supply signal S2 is started, controller <NUM> outputs high frequency voltage application signal S3 at timing t2 so as to perform a start operation where high frequency voltage application unit <NUM> is made to start application of a high frequency high voltage. Then, at this point of time that the voltage applying operation is started, controller <NUM> acquires delay time Tl (see <FIG>) from a point of time that the start operation is started to a point of time that the detection of a welding current more than or equal to the current threshold by current detection unit <NUM> is started, and stores delay time Tl in delay time storage unit <NUM>. Then, controller <NUM> references delay times Tl at a plurality of points of time at which the start operation is performed including a current point of time at which the start operation is performed that are stored in delay time storage unit <NUM>, and determines whether or not delay times Tl at the plurality of points of time at each of which the start operation is performed satisfy a predetermined time condition. Then, controller <NUM> performs processing at an abnormal time in a case where delay times Tl satisfy the predetermined time condition.

The time condition is that the first number N1 (being <NUM> or more) of times of delay times Tl each of which exceeds a predetermined time threshold are included in delay times Tl at a plurality of recent number of points of time at which the start operation is performed. The time condition is stored in controller <NUM>. Controller <NUM> changes the time condition by changing the time threshold in accordance with predetermined setting conditions. The setting conditions are an instruction value of a welding current, a flow rate of a shielding gas, a tip angle of tungsten electrode <NUM>, the dopant concentration in tungsten electrode <NUM>, a diameter of tungsten electrode <NUM>, and a mode that is either an AC output mode or a DC output mode.

The processing at an abnormal time is processing where controller <NUM> makes display unit <NUM> output and display any one of first to fourth warning images based on image data stored in display data storage unit <NUM>. Specifically, in a case where the number LN of delay times Tl each of which exceeds the predetermined time threshold is more than or equal to the first number N1 and less than a predetermined second number N2 among delay times Tl at a plurality of recently-set number of points of time that the start operation is performed, the processing to be performed at an abnormal time becomes a process where controller <NUM> makes display unit <NUM> output and display the first warning image. The second number N2 is a value larger than the first number N1. Specifically, in a case where the number LN of delay times Tl each of which exceeds the predetermined time threshold is more than or equal to the second number N2 and less than a predetermined third number N3 among delay times Tl at the plurality of recently-set number of points of time that the start operation is performed, the processing at an abnormal time becomes a process where controller <NUM> makes display unit <NUM> output and display the second warning image. The third number N3 is a value larger than the second number N2. In a case where the number of delay times Tl each of which exceeds the predetermined time threshold is more than or equal to the third number N3 and less than a predetermined fourth number N4 among delay times Tl at a plurality of recently-set number of points of time that the start operation is performed, the processing at an abnormal time becomes a process where controller <NUM> makes display unit <NUM> output and display the third warning image. The fourth number N4 is a value larger than the third number N3. In a case where the number of delay times Tl each of which exceeds the predetermined time threshold is more than or equal to the fourth number N4 among delay times Tl at a plurality of recently-set number of points of time that the start operation is performed, the processing at an abnormal time becomes a process where controller <NUM> makes display unit <NUM> output and display the fourth warning image. The time thresholds and the first to fourth numbers N1 to N4 are set to appropriate values by experiments in advance.

In the exemplary embodiment, the above-mentioned set number of points of time that the start operation is performed is set to <NUM>, and the numbers of the first to fourth numbers N1 to N4 are set to <NUM>, <NUM>, <NUM> and <NUM> in this order. However, provided that the set number of points of time that the start operation is performed is larger than the first to fourth numbers N1 to N4, the set number of points of time may be set to the number other than <NUM>. Further, the numbers of first to fourth numbers N1 to N4 may also be set to other numbers provided that a relationship described in the following expression <NUM> is established.

Further, controller <NUM> controls welding output circuit unit <NUM> based on welding control signal S4 in such a manner that, from a point of time that a welding current that is more than or equal to the current threshold is detected by current detection unit <NUM> to a point of time that predetermined hot start period Th (see <FIG>) has elapsed, the welding current assumes a predetermined hot start set current value.

The functions of controller <NUM> are implemented by a central processing unit (CPU) and a storage device.

Delay time storage unit <NUM> stores delay time Tl from a point of time that the start operation is started to a point of time that the detection of a welding current that is more than or equal to the above-described current threshold is performed by current detection unit <NUM>.

Hereinafter, an example of the operation of welding device <NUM> when a switch is switched from an OFF state to an ON state is described with reference to a timing chart illustrated in <FIG>.

First, when an operator turns on switch <NUM> of welding torch <NUM> at timing t1, input circuit unit <NUM> outputs welding instruction signal S1 that indicates that input circuit unit <NUM> is in an ON state. In response to welding instruction signal S1, controller <NUM> starts outputting of gas supply signal S2, and gas control device <NUM> makes welding torch <NUM> start jetting of a shield gas to base material <NUM>. Thereafter, when predetermined preflow time Tp has elapsed from a point of time that outputting of gas supply signal S2 by controller <NUM> is started, controller <NUM> outputs high frequency voltage application signal S3 at timing t2 so as to perform a start operation where high frequency voltage application unit <NUM> is made to start application of the high frequency high voltage. Thereafter, an insulation between tungsten electrode <NUM> and base material <NUM> is broken by a high frequency voltage applied by high frequency voltage application unit <NUM>. Accordingly, arc A is generated so that a welding current flows, and current detection unit <NUM> detects a welding current more than or equal to a predetermined current threshold at timing t3. Then, controller <NUM> acquires delay time Tl from a point of time that the start operation is started to a point of time that current detection unit <NUM> detects a welding current more than or equal to the current threshold, and stores acquired delay time Tl. Further, controller <NUM> controls welding output circuit unit <NUM> in such a manner that, from a point of time that a welding current that is more than or equal to the current threshold is detected by current detection unit <NUM> to a point of time that predetermined hot start period Th has elapsed, the welding current assumes a predetermined hot start set current value.

<FIG> is a flowchart for describing detailed processing performed by controller <NUM> when switch <NUM> is switched from an OFF state to an ON state.

When switch <NUM> is switched from an OFF state to an ON state so that welding instruction signal S1 output from input circuit unit <NUM> is switched from a signal indicating an OFF state to a signal indicating an ON state, controller <NUM> starts outputting of gas supply signal S2 in S101.

Next, in S102, controller <NUM> waits for a lapse of predetermined preflow time Tp from a point of time that outputting of gas supply signal S2 is started in S101. Then, when predetermined preflow time Tp has elapsed from a point of time that the outputting of gas supply signal S2 is started in S101, in S103, controller <NUM> performs a start operation by outputting high frequency voltage application signal S3 so as to make high frequency voltage application unit <NUM> start application of a high frequency high voltage.

Next, in S104, controller <NUM> acquires delay time Tl from a point of time that the start operation is started in S103 to a point of time that a welding current more than or equal to the current threshold is detected by current detection unit <NUM>, and controller <NUM> stores delay time Tl in delay time storage unit <NUM>.

Then, in S105, controller <NUM> refers to delay times Tl at recent <NUM> points of time at which the start operation is performed that are stored in delay time storage unit <NUM>, and determines whether or not the time condition that the first number N1, that is, <NUM> or more delay times Tl each of which exceeds the predetermined time threshold are included in the recent <NUM> points of time at which the start operation is performed. In a case where the first number N1 or more of delay times Tl that exceeds the predetermined time threshold are not included so that the time condition is not satisfied, the processing advances to S106. On the other hand, in a case where the first number N1 or more of delay times Tl that exceeds the predetermined time threshold are included so that the time condition is satisfied, the processing advances to S107.

In S106, controller <NUM> does not perform the processing at an abnormal time.

Then, in S107, controller <NUM> refers to delay times Tl at recent <NUM> points of time at which the start operation is performed that are stored in delay time storage unit <NUM>, and determines whether or not the number LN of delay times Tl that exceeds the predetermined time threshold is the second number N2, that is, less than <NUM> among delay times Tl at the recent <NUM> points of time at which the start operation is performed. When the number LN of the delay times Tl that exceeds the predetermined time threshold is less than the second number N2, the processing advances to S108. On the other hand, when the number LN of the delay times exceeding the predetermined time threshold is more than or equal to the second number N2, the processing advances to S109.

In S108, controller <NUM> performs processing of outputting and displaying a first warning image that displays a message that "The electrode is getting smeared. " on display unit <NUM> as the processing at an abnormal time.

Then, in S109, controller <NUM> refers to delay times Tl at recent <NUM> points of time at which the start operation is performed that are stored in delay time storage unit <NUM>, and determines whether or not the number LN of delay times Tl that exceeds the predetermined times threshold is the third number N3, that is, less than <NUM> among delay times Tl at the recent <NUM> points of time at which the start operation is performed. When the number LN of delay times Tl exceeding the predetermined time threshold is less than the third number N3, the processing advances to S110. On the other hand, when the number LN of delay times Tl exceeding the predetermined time threshold is more than or equal to the third number N3, the processing advances to S111.

In S110, controller <NUM> performs processing of outputting and displaying a second warning image that "The electrode is worn so that there is a possibility that the generation of an arc does not start. " on the display unit <NUM> as the processing at an abnormal time.

In S111, controller <NUM> refers to delay times Tl at recent <NUM> points of time at which the start operation is performed that are stored in delay time storage unit <NUM>, and determines whether or not the number LN of delay times Tl that exceeds the predetermined time threshold is the fourth number N4, that is, less than <NUM> among delay times Tl at the recent <NUM> points of time at which the start operation is performed. When the number LN of delay times Tl exceeding the predetermined time threshold is less than the fourth number N4, the processing advances to S112. On the other hand, when the number LN of delay times Tl exceeding the predetermined time threshold is more than or equal to the fourth number N4, the processing advances to S113.

In S112, controller <NUM> performs processing of making the display unit <NUM> output and display a third warning image "Wear of the electrode is large and smear on the electrode is large. Polishing of the electrode is recommended. " as the processing at an abnormal time.

In S113, controller <NUM> performs processing of making display unit <NUM> output and display the fourth warning image that "Please polish or exchange the electrode. " as the processing at an abnormal time.

In general, when tungsten electrode <NUM> is worn or smeared, it becomes difficult to shift an operation state to an arc discharge state, and the time from the generation of the high frequency voltage to the start of the flow of the welding current, that is, the delay time Tl becomes long. In the exemplary embodiment, when the frequency at which the delay time Tl exceeds the time threshold becomes high, controller <NUM> performs the processing at an abnormal time, and display unit <NUM> displays the first to fourth warning images. Accordingly, an operator can recognize the consumption or a smear on tungsten electrode <NUM>, and can take a measure such as polishing tungsten electrode <NUM> or exchanging tungsten electrode <NUM>. Therefore, it is possible to suppress the occurrence of a state where starting of an arc takes an excessively long time or starting of an arc cannot be performed due to consumption or smear on tungsten electrode <NUM>.

The controller determines whether or not the processing at an abnormal time should be performed based on the delay times Tl at a plurality of points of time at which the start operation is performed. Accordingly, compared with the case where the controller determines whether or not the processing at an abnormal time should be performed based on the delay time at a point of time at which the start operation is performed one time as described in PTL <NUM>, the processing at an abnormal time is minimally performed due to a temporary factor other than the consumption and the smear on tungsten electrode <NUM>. Therefore, unnecessary polishing or exchange of tungsten electrode <NUM> can be suppressed.

In a first modification of the present exemplary embodiment, the time condition is that delay time Tl in the current start operation exceeds predetermined threshold TH (see <FIG>), and the number of times of the start operation performed between the current start operation and the previous start operation in which the delay time Tl exceeds the threshold TH is less than a predetermined reference number of times. In the first modification, the reference number of times is set to <NUM> times. However, the reference number of times may be set to another number of times. In addition, the processing at an abnormal time may be always processing in which the first warning image is output to and displayed on display unit <NUM>.

For example, in an example illustrated in <FIG>, delay time Tl exceeds threshold TH in the S1-th start operation, the S2 (= S1 + <NUM>)-th start operation, and the S3 (= S2 + <NUM>)-th start operation. In this case, at the point of time that the S2-th start operation is performed, the number of times NU1 of the start operations performed between the current start operation and the previous start operation in which the delay time Tl exceeds the threshold TH, that is, the S1-th start operation is <NUM> times or more, that is, <NUM> times, and the time condition is not satisfied. Therefore, controller <NUM> does not make the display unit <NUM> output and display the first warning image.

On the other hand, at the point of time that the S3-th start operation is performed, the number of times NU2 of the start operations performed between the current start operation and the previous start operation in which the delay time Tl exceeds threshold TH, that is, the S2-th start operation is less than <NUM> times, that is, <NUM> times, and the time condition is satisfied. Therefore, controller <NUM> makes display unit <NUM> output and display the first warning image.

Other configurations and operations are the same as the configurations and the operations in the above exemplary embodiment and hence, the detailed description thereof will be omitted.

Also in a second modification of the exemplary embodiment, the processing at an abnormal time is always processing in which the first warning image is output and displayed on display unit <NUM>.

In addition, the time condition satisfies at least one among a first condition that the delay time Tl in the current start operation exceeds the predetermined first time threshold, a second condition that the number of delay times Tl that exceed the predetermined second time threshold is included in delay times Tl at a plurality of recently-set points of time including the present time at which the start operation is performed, and the number of such delay times Tl is more than or equal to a predetermined reference number, and a third condition that delay time Tl at the current start operation exceeds the predetermined third time threshold and the number of the start operations performed between the current start operation and the previous start operation in which delay time Tl exceeds a third time threshold becomes less than a predetermined reference number of times. The first to third time thresholds are set so as to satisfy the following expression <NUM>.

Also in a third modification of the exemplary embodiment, the processing at an abnormal time always is processing where controller <NUM> makes display unit <NUM> output and display the first warning image.

Further, the time condition is that the variance of delay times Tl that are acquired at a plurality of recently-set number of points of time at which the start operation is performed becomes more than or equal to a predetermined value. The set number of times is, for example, <NUM> times. When the wear and the smear on tungsten electrode <NUM> are small, delay time Tl is relatively constant. Accordingly, the variance becomes small. However, along with the increase of wear and smear on tungsten electrode <NUM>, the variance is increased. Accordingly, the wear and the smear on tungsten electrode <NUM> can be estimated based on the variance.

The processing at an abnormal time may be processing where any one of the first to fourth warning images is selected, and is output and displayed corresponding to a value of the variance.

In a fourth modification of the exemplary embodiment, controller <NUM> performs processing where a hot start set current value is changed to a larger current value as a processing at an abnormal time (according to the claimed invention) in place of the processing where any one of the first to fourth warning images is output to and is displayed on display unit <NUM> (not according to the claimed invention). As a result, tungsten electrode <NUM> can be warmed faster. The hot start set current value is increased to such an extent that tungsten electrode <NUM> is not excessively consumed.

The time condition is not limited to the conditions described in the above-described exemplary embodiment and the first to fourth modifications of the exemplary embodiment. Other appropriate conditions may be set by experiments. In the above-described exemplary embodiment and the first to fourth modifications, the time condition is set in such a manner that when delay times at a plurality of previous points of time at which the start operation is performed before the current time are input to a predetermined function, an output value of the function satisfies a predetermined numerical value condition. However, the time condition may be set in such a manner that when delay times at a plurality of previous points of time of start operation before the current time are input to artificial intelligence (AI), an output of the AI satisfies a predetermined condition.

Further, in the fourth modification of the above-described exemplary embodiment, the processing at an abnormal time is set to the processing where a hot start set current value is increased. However, the processing at an abnormal time may be set to processing where an after-flow time during which a shielding gas is continuously released after finishing of welding is prolonged (not according to the claimed invention). Further, the processing at an abnormal time may be set to processing where other parameters such as a frequency of an output during an operation in an AC output mode are changed.

Further, as the processing at an abnormal time, controller <NUM> may perform both the processing where a hot start set current value is increased and the processing where controller <NUM> makes display unit <NUM> output and display the warning image.

Further, the processing at an abnormal time is not limited to the processing where controller <NUM> makes display unit <NUM> output an image, and may make a voice output device output a voice.

In the above-described exemplary embodiment, controller <NUM> changes the time condition in accordance with six setting conditions consisting of: an instruction value of a welding current, a flow rate of a shielding gas, a tip end angle of tungsten electrode <NUM>, the dopant concentration in tungsten electrode <NUM>, a diameter of tungsten electrode <NUM>, and whether the mode is an alternating current (AC) output mode or a direct current (DC) output mode. However, the time condition may be changed in accordance with only a part of at least one of the six setting conditions. The time condition may not be changed.

Claim 1:
A welding device (<NUM>) that is configured to perform welding by generating an arc (A) between a tungsten electrode (<NUM>) and a welding target (<NUM>), the welding device (<NUM>) comprising:
a high frequency voltage application unit (<NUM>) configured to apply a high frequency voltage between the tungsten electrode (<NUM>) and the welding target (<NUM>);
a welding output circuit unit (<NUM>) configured to control a welding current;
a current detection unit (<NUM>) configured to detect the welding current that is more than or equal to a predetermined current threshold; and
a controller (<NUM>) configured, at a time of performing a start operation for making the high frequency voltage application unit (<NUM>) start applying of the high frequency voltage, to acquire a delay time (T1) from a point of time that the start operation is performed to a point of time that the welding current is detected by the current detection unit (<NUM>),
characterized in that the controller (<NUM>) is further configured to determine whether or not delay times corresponding to the delay time that are acquired at a plurality of previous points of time at which the start operation is performed satisfy a predetermined time condition, and to perform predetermined abnormality processing in a case where the delay times satisfy the predetermined time condition, and
in that the time condition is that the delay time at the start operation of the present time exceeds a predetermined threshold, and the number of times of the start operations performed between the start operation of the present time and the start operation of a previous time where the delay time exceeds the predetermined threshold is less than a predetermined reference number of times.