Argon arc welding pulling arc starting anti-sticking device and argon arc welding device

Abstract

The application is suitable for the technical field of welding machine, and provides an argon arc welding pulling arc sticking prevention device and an argon arc welding device.The argon arc welding pulling arc sticking prevention device comprises: an auxiliary voltage output circuit, which is used for outputting a preset direct current voltage to an output end of an argon arc welding body; a short circuit judgment circuit, which is used for detecting the voltage of the output end of the argon arc welding body to judge whether the tungsten needle of the argon arc welding body is in contact with a workpiece; and a current adjusting circuit, which is used for outputting no control signal when the tungsten needle of the argon arc welding body is not in contact with the workpiece, and outputting a control signal for making the current output by the output end of the argon arc welding body start from zero and gradually increase when the tungsten needle of the argon arc welding body is in contact with the workpiece, so that the overshoot of the short circuit current is avoided, the problem of the tungsten needle being burned due to the excessively large current caused by the short circuit current being a relatively large current value is avoided, and the problem of the tungsten needle being in contact with the workpiece is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of welding machines, and particularly relates to an argon arc welding pulling arc starting anti-sticking device and an argon arc welding device. BACKGROUND

[0002] The arc starting modes of argon arc welding mainly include high-frequency discharge arc starting and contact arc starting. In order to reduce the cost and resist high-frequency discharge interference, in a multi-functional inverter welding machine mainly without argon arc welding function, argon arc welding is usually simple argon arc welding and adopts the contact arc starting mode. In the contact arc starting mode, the tungsten needle of the argon arc welding gun needs to be in contact with the welding workpiece to pull up the welding gun to form an arc. As shown in FIG. 1, 101 represents a contact action and 102 represents a pulling action. Figure 1

[0003] The contact arc starting mode has certain disadvantages. When the tungsten needle is separated from the workpiece, the tungsten needle is stuck, that is, the welding gun needs to be pulled up with a certain force, and some workpiece metal is mixed on the tungsten needle, or a small amount of tungsten metal on the tungsten needle is mixed on the workpiece, which affects the welding operation and the welding quality of the workpiece. How to prevent the tungsten needle from being stuck with the workpiece is a technical problem to be solved by the present application. SUMMARY

[0004] Therefore, the present application provides an argon arc welding pulling arc starting anti-sticking device and an argon arc welding device to solve the problem of the tungsten needle being stuck with the workpiece.

[0005] The first aspect of the present application provides an argon arc welding pulling arc starting anti-sticking device, which comprises:

[0006] an auxiliary voltage output circuit, which is configured to output a preset direct current voltage to an output end of an argon arc welding body;

[0007] a short circuit judgment circuit, which is configured to detect the voltage of the output end of the argon arc welding body to determine whether the tungsten needle of the argon arc welding body is in contact with a workpiece; and

[0008] a current adjusting circuit, which is connected to the output end of the short circuit judgment circuit, and is configured to have no output when the tungsten needle of the argon arc welding body is not in contact with the workpiece, and output a control signal for gradually increasing the current output by the output end of the argon arc welding body from zero when the tungsten needle of the argon arc welding body is in contact with the workpiece.

[0009] In one embodiment, the auxiliary voltage output circuit comprises a rectifier, a power supply switch, a relay and a power supply circuit. The direct current side of the rectifier is connected to one end of the contact switch of the relay, the other end of the contact switch of the relay is configured to be connected to the output end of the argon arc welding body, and the power supply switch and the control coil of the relay are arranged in series in the power supply circuit.​

[0010] In one embodiment, the power supply switch is an electrically controlled electronic switch device.

[0011] In one embodiment, the short circuit judgment circuit comprises a first comparator, a non-inverting input terminal of the first comparator being connected to a preset reference voltage, an inverting input terminal of the first comparator being connected to an output terminal of the argon arc welding body, and an output terminal of the first comparator outputting a judgment signal, based on which it is determined whether the tungsten needle of the argon arc welding body is in contact with the workpiece.

[0012] In one embodiment, the short circuit judgment circuit further comprises a first operational amplifier and a second operational amplifier, an input terminal of the first operational amplifier being connected to the preset reference voltage, an output terminal of the first operational amplifier being connected to a non-inverting input terminal of the first comparator, and an input terminal of the second operational amplifier being connected to the output terminal of the argon arc welding body, an output terminal of the second operational amplifier being connected to an inverting input terminal of the first comparator.

[0013] In one embodiment, the current regulation circuit comprises a current regulator, a unidirectional conducting device and a PWM controller, the short circuit judgment circuit further comprises a charging capacitor and a pull-up resistor, an output terminal of the first comparator being connected to one end of the charging capacitor, the other end of the charging capacitor being grounded, the output terminal of the first comparator being connected to a power supply through the pull-up resistor, an output terminal of the current regulator being connected to an input terminal of the unidirectional conducting device and an input terminal of the PWM controller, an output terminal of the unidirectional conducting device being connected to the output terminal of the first comparator, and an output terminal of the PWM controller being used to output a corresponding PWM control signal.

[0014] In one embodiment, the current regulator is a current PI regulator.

[0015] In one embodiment, the current PI regulator comprises a second operational amplifier, an inverting input terminal of the second operational amplifier being connected to a current given signal and a current feedback signal, a non-inverting input terminal of the second operational amplifier being grounded, and an output terminal of the second operational amplifier being connected to an input terminal of the PWM controller.

[0016] In one embodiment, the current PI regulator further comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second capacitor, one end of the first resistor is connected to the inverting input terminal of the second operational amplifier, the other end of the first resistor is used to access the current given signal, one end of the second resistor is connected to the inverting input terminal of the second operational amplifier, the other end of the second resistor is used to access the current feedback signal, the third resistor and the first capacitor are connected in series to form a series branch, one end of the series branch is connected to the inverting input terminal of the second operational amplifier, the other end of the series branch is connected to the output terminal of the second operational amplifier; the output terminal of the second operational amplifier is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is grounded, the connection point of the fourth resistor and the fifth resistor is connected to the input terminal of the unidirectional conduction device and the input terminal of the PWM controller, and the fifth resistor is connected in parallel with the second capacitor.

[0017] The second aspect of the embodiment of the present application provides an argon arc welding device, comprising:

[0018] an argon arc welding body; and

[0019] The argon arc welding pulling arc sticking prevention device provided in the first aspect of the embodiment of the present application.

[0020] Compared with the prior art, the embodiment of the present application has the beneficial effects that: when the tungsten needle is not in contact with the workpiece, the voltage of the output end of the argon arc welding body is high, when the tungsten needle is in contact with the workpiece, the tungsten needle is short-circuited, the voltage of the output end of the argon arc welding body is reduced, and the voltage of the output end of the argon arc welding body is detected by the short-circuit judgment circuit to determine whether the tungsten needle is in contact with the workpiece; when the tungsten needle is not in contact with the workpiece, the current regulation circuit has no output, when the tungsten needle is in contact with the workpiece, the current regulation circuit starts to output, and an output control signal is output, so that the current output by the output end of the argon arc welding body starts from zero and gradually increases, the short-circuit current does not overshoot, the problem of the tungsten needle being burned due to the excessively large current caused by the short-circuit current directly being a relatively large current value is avoided, and the problem of the tungsten needle being stuck to the workpiece is solved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 is a pulling arc schematic diagram;

[0023] Figure 2 is a schematic diagram of a pull-arc current overshoot;

[0024] Figure 3 is a first structural schematic diagram of the argon arc welding pull-arc anti-sticking device provided by Embodiment One of the present application;

[0025] Figure 4 is a second structural schematic diagram of the argon arc welding pull-arc anti-sticking device provided by Embodiment One of the present application;

[0026] Figure 5 is a circuit diagram of an auxiliary voltage output circuit of the argon arc welding pull-arc anti-sticking device provided by Embodiment One of the present application;

[0027] Figure 6 is a circuit diagram of a short-circuit judgment circuit and a current regulator of the argon arc welding pull-arc anti-sticking device provided by Embodiment One of the present application;

[0028] Figure 7 is a circuit diagram of a PWM controller;

[0029] Figure 8 is a circuit diagram of a main circuit of the argon arc welding body;

[0030] Figure 9 is a schematic diagram of improved pull-arc related waveforms. DETAILED DESCRIPTION

[0031] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular sequences of steps, techniques, etc., in order to provide a thorough understanding of the present embodiments. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, and circuits are omitted so as not to obscure the description of the present application with unnecessary detail.

[0032] It is to be understood that the terminology "including," "includes," "has," and / or "have," when used in this specification, specifies the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] It is also to be understood that the terminology and phraseology used herein is solely used for the purpose of description and not of limitation. As used in this specification and the appended claims, the singular "a," "an," and "the" encompass the plural reference unless the context clearly indicates otherwise.

[0034] In order to illustrate the technical solutions described in the present application, the following will be described through specific embodiments.

[0035] First, briefly explain the reason for the adhesion of the tungsten needle and the workpiece:

[0036] Before welding, the main power supply of the argon arc welding body 304 is in an open state, that is, the argon arc welding body 304 has an idle voltage output when the tungsten needle is not in contact with the workpiece, Figure 2 201 is the voltage waveform of the pull-arc argon arc welding, 202 is the current waveform of the pull-arc argon arc welding, and the PWM drive of the switch tube controlling the current output is usually the maximum pulse width at this time. To avoid burning of the tungsten needle due to excessive current when in contact, the contact short-circuit current is generally set to 10-25A, 203 is the control voltage signal output by the current regulator, and 204 is the PWM control signal corresponding to the control voltage signal output by the current regulator. The PI regulation of the current regulator usually has a certain lag, and the response time of the short-circuit processing is generally 1-2ms, that is, the time for the PWM drive to change from the maximum pulse width to the pulse width corresponding to 10-25A is 1-2ms. In this period of time, since the current has not changed to 10-25A, the short-circuit current will be very large, sometimes reaching more than 150A, which is the current overshoot, as shown in the current waveform 205 in Figure 2 Such a large current generates a large amount of heat when short-circuiting, causing the tungsten needle and the workpiece to melt at the contact position. When the current decreases to 10-25A, the molten metal cools and solidifies, causing the tungsten needle and the workpiece to adhere.

[0037] Referring to Figure 3 is a first structure diagram of the argon arc welding pull-arc anti-adhesion device provided by Embodiment One of the present application. For ease of illustration, only the parts related to the present application are shown.

[0038] The argon arc welding pull-arc anti-adhesion device comprises an auxiliary voltage output circuit 301, a short-circuit judgment circuit 302, and a current regulation circuit 303.

[0039] The auxiliary voltage output circuit 301 outputs a preset direct current voltage. The specific value of the direct current voltage is set according to actual needs. To ensure the accuracy of the subsequent short-circuit judgment and prevent the short-circuit misjudgment caused by the direct current voltage being set too low, the direct current voltage should not be set too low. In the present embodiment, the value of the direct current voltage can be 15V. The voltage output end of the auxiliary voltage output circuit 301 is connected to the output end of the argon arc welding body 304 (i.e. the positive and negative output ends of the argon arc welding body 304), and outputs the direct current voltage to the output end of the argon arc welding body 304, so that the output end of the argon arc welding body 304 outputs the 15V direct current. The auxiliary voltage output circuit 301 can be a specific circuit structure or a power supply chip with a direct current voltage output function.

[0040] The short-circuit judgment circuit 302 is used for detecting the voltage of the output end of the argon arc welding body 304, and setting a voltage threshold value which is less than the direct current voltage output by the auxiliary voltage output circuit 301. The specific value of the voltage threshold value is set according to the actual situation. In the embodiment, the voltage threshold value can be set to 5V. The voltage threshold value is used for judging the size of the voltage of the output end of the argon arc welding body 304 and the voltage threshold value, and then judging whether the tungsten needle of the argon arc welding body 304 contacts the workpiece according to the voltage of the output end of the argon arc welding body 304. Specifically, when the tungsten needle of the argon arc welding body 304 does not contact the workpiece, the tungsten needle of the argon arc welding body 304 does not short-circuit with the workpiece, and the voltage of the output end of the argon arc welding body 304 is 15V, which is greater than the voltage threshold value 5V; when the tungsten needle of the argon arc welding body 304 contacts the workpiece, the tungsten needle of the argon arc welding body 304 short-circuits with the workpiece, and the voltage of the output end of the argon arc welding body 304 will be greatly reduced, which will be less than 5V. Therefore, when the short-circuit judgment circuit 302 detects that the voltage of the output end of the argon arc welding body 304 is greater than 5V, it is determined that the tungsten needle of the argon arc welding body 304 does not contact the workpiece; when the short-circuit judgment circuit 302 detects that the voltage of the output end of the argon arc welding body 304 is less than 5V, it is determined that the tungsten needle of the argon arc welding body 304 contacts the workpiece. The short-circuit judgment circuit 302 can include a comparator for comparing the voltage of the output end of the argon arc welding body 304 and the voltage threshold value, thereby outputting a corresponding signal; it can also be a specific comparison circuit or a data processing chip, which realizes voltage comparison through internal software programs corresponding to voltage comparison functions.

[0041] The current regulation circuit 303 is connected with the output end of the short-circuit judgment circuit 302. The current regulation circuit 303 controls the current output according to the judgment result of whether the tungsten needle of the argon arc welding body 304 contacts the workpiece judged by the short-circuit judgment circuit 302. Specifically, when the tungsten needle of the argon arc welding body 304 does not contact the workpiece, the current regulation circuit 303 has no output; when the tungsten needle of the argon arc welding body 304 contacts the workpiece, the current regulation circuit 303 outputs a control signal, which is used to make the current output by the output end of the argon arc welding body 304 start from zero and gradually increase, thereby avoiding overshoot. Therefore, the control signal can be output to the switching device in the main circuit of the argon arc welding body 304. The current regulation circuit 303 can be a conventional current regulator, which outputs a controllable control signal; it can also include a current regulator and a PWM controller; it can also be a control chip with regulation function.

[0042] Referring to Figure 4 , it is the second structure schematic diagram of the argon arc welding pulling arc and anti-sticking device provided by the embodiment one of the present application. For the convenience of description, only the parts related to the embodiment of the present application are shown.

[0043] The argon arc welding pulling arc sticking prevention device comprises an auxiliary voltage output circuit 401, a short circuit judgment circuit 402 and a current adjusting circuit. The current adjusting circuit comprises a current adjuster 403 and a PWM controller 404.

[0044] The auxiliary voltage output circuit 401 outputs a preset direct current voltage. The specific value of the direct current voltage is set according to actual needs. However, in order to ensure the accuracy of subsequent short circuit judgment and prevent short circuit misjudgment caused by setting the direct current voltage too low, the direct current voltage should not be set too low. In the embodiment, the value of the direct current voltage can be 15V. The voltage output end of the auxiliary voltage output circuit 401 is connected to the output end of the argon arc welding body 405 (i.e. the positive and negative output ends of the argon arc welding body 405), and outputs the direct current voltage to the output end of the argon arc welding body 405, so that the output end of the argon arc welding body 405 outputs the 15V direct current.

[0045] The short circuit judgment circuit 402 is used to detect the voltage of the output end of the argon arc welding body 405 and set a voltage threshold value. The voltage threshold value is less than the direct current voltage output by the auxiliary voltage output circuit 401. The specific value of the voltage threshold value is set according to actual conditions. In the embodiment, the voltage threshold value can be set to 5V. The voltage threshold value is used to judge the size of the voltage of the output end of the argon arc welding body 405 and the voltage threshold value, and then judge whether the tungsten needle of the argon arc welding body 405 is in contact with the workpiece according to the voltage of the output end of the argon arc welding body 405. Specifically, when the tungsten needle of the argon arc welding body 405 is not in contact with the workpiece, the tungsten needle of the argon arc welding body 405 is not short-circuited with the workpiece, and the voltage of the output end of the argon arc welding body 405 is 15V, which is greater than the voltage threshold value 5V. When the tungsten needle of the argon arc welding body 405 is in contact with the workpiece, the tungsten needle of the argon arc welding body 405 is short-circuited with the workpiece, and the voltage of the output end of the argon arc welding body 405 will be greatly reduced and will be less than 5V. Therefore, when the short circuit judgment circuit 402 detects that the voltage of the output end of the argon arc welding body 405 is greater than 5V, it is determined that the tungsten needle of the argon arc welding body 405 is not in contact with the workpiece. When the short circuit judgment circuit 402 detects that the voltage of the output end of the argon arc welding body 405 is less than 5V, it is determined that the tungsten needle of the argon arc welding body 405 is in contact with the workpiece.

[0046] The output end of the short circuit judgment circuit 402 is connected to the output end of the current adjuster 403, the output end of the current adjuster 403 is connected to the input end of the PWM controller 404, and the output end of the PWM controller 404 is connected to the argon arc welding body 405.

[0047] When the short-circuit judging circuit 402 judges that the argon arc welding body 405 is not in contact with the workpiece, the short-circuit judging circuit 402 controls the current regulator 403 to output nothing, so that the control voltage output by the current regulator 403 is 0V; when the short-circuit judging circuit 402 judges that the argon arc welding body 405 is in contact with the workpiece, the short-circuit judging circuit 402 controls the control voltage output by the current regulator 403 to gradually increase from 0V, and the control voltage increases to the normal output in about 5ms, and the current regulator 403 outputs the control voltage to the PWM controller 404, the PWM controller 404 outputs the PWM control signal, the duty cycle of the PWM control signal corresponds to the control voltage output by the current regulator 403, the higher the control voltage, the greater the duty cycle, so that the output current of the output end of the argon arc welding body 405 also gradually increases from 0A (up to about 10A), thereby avoiding overshoot.

[0048] Figure 5 A specific circuit structure of the auxiliary voltage output circuit 401 is given. As shown in Figure 5 , the auxiliary voltage output circuit 401 includes a rectifier 501, a relay, a power supply switch 502 and a power supply loop. The AC side of the rectifier 501 is used to connect an AC power supply, in this embodiment, the AC side of the rectifier 501 is connected to the power supply interface 505, and the power supply interface 505 is connected to the AC power supply. The DC side of the rectifier 501 is connected to one end of the contact switch 503 of the relay, and the other end of the contact switch 503 of the relay is the output end of the auxiliary voltage output circuit 401. One end of the power supply loop is connected to a power supply, in this embodiment, the power supply is taken as an example of +5V, and the other end is grounded. The power supply switch 502 and the control coil 504 of the relay are connected in series in the power supply loop. In this embodiment, the power supply switch 502 is an electrically controlled electronic switching device, such as a triode or a MOS tube. The control end of the power supply switch 502 is used to input a control instruction, such as connecting the IO port VRDCtrl of a single-chip microcomputer, and the single-chip microcomputer outputs the control instruction to control whether to output the auxiliary voltage. In order to protect the power supply switch 502, a resistor 506 is arranged at the control end of the power supply switch 502, and a resistor 507 is arranged between the control end of the power supply switch 502 and the ground. In order to protect the control coil 504 of the relay, the control coil 504 of the relay is connected in antiparallel with a diode 508. The DC side of the rectifier 501 is provided with a filter capacitor 509 and a resistor 510. The output end of the auxiliary voltage output circuit 401 is also provided with a resistor 512 and a resistor 513. The output end of the auxiliary voltage output circuit 401 is used to connect the output end of the argon arc welding body 405.

[0049] As Figure 6As shown, the short-circuit judging circuit 402 comprises a first comparator 601, a first operational amplifier 602 and a second operational amplifier 603. A preset reference voltage Us is input to the non-inverting input terminal of the first operational amplifier 602. In the embodiment, the preset reference voltage Us is input to the non-inverting input terminal of the first operational amplifier 602 through a resistor 604, and the non-inverting input terminal of the first operational amplifier 602 is grounded through a capacitor 605. The inverting input terminal of the first operational amplifier 602 is connected to the output terminal of the first operational amplifier 602, and the output terminal of the first operational amplifier 602 is connected to the non-inverting input terminal of the first comparator 601. In the embodiment, the output terminal of the first operational amplifier 602 is connected to the non-inverting input terminal of the first comparator 601 through a resistor 606. The non-inverting input terminal of the second operational amplifier 603 is used to connect the output terminal of the argon arc welding body 405 to input the actual voltage Uf (the actual voltage is the feedback voltage) of the output terminal of the argon arc welding body 405. In the embodiment, the actual voltage Uf is input to the non-inverting input terminal of the second operational amplifier 603 through a resistor 607, and the non-inverting input terminal of the second operational amplifier 603 is grounded through a capacitor 608. The inverting input terminal of the second operational amplifier 603 is connected to the output terminal of the second operational amplifier 603, and the output terminal of the second operational amplifier 603 is connected to the inverting input terminal of the first comparator 601. In the embodiment, the output terminal of the second operational amplifier 603 is connected to the inverting input terminal of the first comparator 601 through a resistor 609.

[0050] The short-circuit judging circuit 402 further comprises a charging capacitor 610 and a pull-up resistor 611. One end of the charging capacitor 610 is connected to the output terminal of the first comparator 601, and the other end of the charging capacitor 610 is grounded. The output terminal of the first comparator 601 is connected to a power supply VCC through the pull-up resistor 611. In the embodiment, the power supply VCC is taken as +15V as an example.

[0051] The power supply of the first comparator 601 is +15V, which is connected to the positive power supply terminal of the first comparator 601. The positive power supply terminal of the first comparator 601 is grounded through a capacitor 612, and the negative power supply terminal of the first comparator 601 is grounded. The power supplies of the first operational amplifier 602 and the second operational amplifier 603 are +15V and -15V. In the second operational amplifier 603 (the same as the first operational amplifier 602), +15V is connected to the positive power supply terminal of the second operational amplifier 603, the positive power supply terminal of the second operational amplifier 603 is grounded through a capacitor 614, -15V is connected to the negative power supply terminal of the second operational amplifier 603, and the negative power supply terminal of the second operational amplifier 603 is grounded through a capacitor 613. The output terminal of the first comparator 601 is the output terminal JTL of the short-circuit judging circuit 402, which is used to output a judging signal. According to the level of the judging signal, it is judged whether the tungsten needle of the argon arc welding body 405 is in contact with the workpiece.

[0052] In the above description, the first operational amplifier 602 is used to amplify the preset reference voltage Us, and the second operational amplifier 603 is used to amplify the actual voltage Uf. The amplified voltage signal can improve the reliability of the voltage comparison. Those skilled in the art should know that if it is not necessary to amplify the voltage signal, the first operational amplifier 602 and the second operational amplifier 603 may not be required.

[0053] In this embodiment, the current regulator 403 is a current PI regulator. Figure 6 As shown, the current PI regulator includes a second operational amplifier 620, a first resistor 621, a second resistor 622, a third resistor 623, a fourth resistor 626, a fifth resistor 627, a first capacitor 624, and a second capacitor 628. The current setpoint signal Is is input to the inverting input terminal of the second operational amplifier 620 through the first resistor 621. The current feedback signal If (i.e., the current at the output terminal of the main circuit of the argon arc welding body 405) is input to the inverting input terminal of the second operational amplifier 620 through the second resistor 622. The non-inverting input terminal of the second operational amplifier 620 is grounded. The third resistor 623 and the capacitor 624 are connected in series to form a series branch. One end of this series branch is connected to the inverting input terminal of the second operational amplifier 620, and the other end is connected to the output terminal of the second operational amplifier 620. The output terminal of the second operational amplifier 620 is connected to one end of the fourth resistor 626. The other end of the fourth resistor 626 is connected to one end of the fifth resistor 627. The other end of the fifth resistor 627 is grounded. The fifth resistor 627 and the second capacitor 628 are connected in parallel.

[0054] The current regulation circuit also includes a unidirectional conducting device 631. The unidirectional conducting device 631 can be a single diode, multiple diodes connected in parallel / series, or a combination circuit of diodes and other components. The connection point of the fourth resistor 626 and the fifth resistor 627 is connected to the input terminal of the unidirectional conducting device 631, i.e., the anode of the diode. The output terminal JTL of the short-circuit detection circuit 402 is connected to the output terminal of the unidirectional conducting device 631, i.e., the cathode of the diode. The connection point of the fourth resistor 626 and the fifth resistor 627 is the output terminal UT of the current regulator 403.

[0055] In this embodiment, as Figure 7As shown, the PWM controller 404 includes a current module PWM controller 701, which is a UC3846. The current module PWM controller 701 is a conventional chip, and the following briefly introduces the pins. Pin 1: current limiting signal / soft start input, which can be connected to a corresponding given signal; pin 2: reference power output, which outputs a reference voltage with excellent temperature characteristics; pin 3: current detection comparator inverting input, which can be connected to a current detection signal; pin 4: current detection comparator non-inverting input, which can be connected to a corresponding given signal; pin 5: error amplifier non-inverting input, which can be connected to a corresponding given signal in a closed loop or open loop system; pin 6: error amplifier inverting input, which is connected to an output feedback signal in a closed loop system, and a feedback network with different functions can be connected between the pin 6 and pin 7 according to needs, to form a proportional, integral, proportional integral or other type of closed loop regulator, and in a switching system, the pin 6 is directly connected to the pin 7 to form a follower; pin 7: error amplifier output; pin 8: oscillator timing capacitor input; pin 9: oscillator timing resistor input; pin 10: synchronization signal input, which inputs a square wave signal to realize external synchronization of the controller, and the pin 10 can also be used as a synchronization pulse signal output terminal to output a synchronization pulse signal to an external circuit; pin 11: output terminal A; pin 12: signal ground; pin 13: output stage bias voltage input; pin 14: output terminal B, the pin 14 and the pin 11 are two complementary output terminals; pin 15: bias power input; pin 16: external shutdown signal input.

[0056] The peripheral circuit of the current module PWM controller 701 is also conventional technology, Figure 7A specific circuit structure is given. Pin 1 is grounded through capacitor 702, capacitor 702 is connected in parallel with resistor 703, pin 1 is connected to one end of resistor 704, and the other end of resistor 704 is connected to pin 2. Pin 2 outputs a reference power supply VREF, and pin 2 is grounded through capacitor 705. Pin 3 is grounded. Pin 4 is grounded through capacitor 706. Pin 5 is grounded through resistor 707, and pin 5 is a control voltage input terminal of current module PWM controller 701, and is connected to the output terminal UT of current regulator 403. Pin 6 is connected to pin 7, and pin 7 is grounded through capacitor 708. Pin 8 is connected to the base of transistor 709 and one end of capacitor 712, the collector of transistor 709 is connected to reference power supply VREF, the emitter of transistor 709 is connected to one end of resistor 711 and one end of resistor 714, the other end of resistor 711 is connected to one end of resistor 710, the other end of resistor 710 is a current sampling terminal, used to input the transformer primary side current sampling value Ic of the main circuit of argon arc welding body 405, and pin 4 is connected to the connection point of resistor 711 and resistor 710. The other end of capacitor 712 and the other end of resistor 714 are grounded. Pin 9 is grounded through resistor 713. Pin 10 is left floating. Pins 11 and 14 are PWM control signal output terminals of current module PWM controller 701, used to output PWM control signals. Pin 12 is grounded. Pin 13 is connected to power supply +15V, pin 13 is connected to one end of capacitor 715 and one end of capacitor 716, and the other end of capacitor 715 and the other end of capacitor 716 are grounded. Pin 15 is connected to power supply +15V, pin 15 is connected to one end of capacitor 717, and the other end of capacitor 717 is grounded. Pin 16 is connected to one end of capacitor 718, and the other end of capacitor 718 is grounded.

[0057] Figure 8 A specific circuit diagram of the main circuit of argon arc welding body 405 is given, including full-bridge rectifier circuit 801, full-bridge inverter circuit 802, transformer 804, rectifier circuit 804 and filter inductor 805, the AC side of full-bridge rectifier circuit 801 is used to connect AC power, the DC side of full-bridge rectifier circuit 801 is connected to the DC side of full-bridge inverter circuit 802, the AC side of full-bridge inverter circuit 802 is connected to the primary winding of transformer 803, the secondary winding of transformer 803 is connected to the AC side of rectifier circuit 804, the DC side of rectifier circuit 804 is output through filter inductor 805, and is output to the output terminal of argon arc welding body 405. Full-bridge rectifier circuit 801 is a controllable full-bridge circuit or an uncontrollable full-bridge circuit, and full-bridge inverter circuit 802 is composed of four switching tubes. The switching tubes in full-bridge inverter circuit 802 of the main circuit of argon arc welding body 405 are driven by the PWM control signals output by the PWM control signal output terminal of current module PWM controller 701, and the duty ratio of the PWM control signals determines the current and voltage of the output terminal of argon arc welding body 405. The main circuit of argon arc welding body 405 belongs to a conventional circuit, and the present application is not limited to Figure 8The specific circuit structure is shown. Figure 8 Ic in the equation (1) is Figure 7 Ic in the equation (1) is Figure 8 If in the equation (1) is Figure 6 If in the equation (1) is

[0058] The maximum current of the output end of the argon arc welding body 405 is set to 10A.

[0059] The auxiliary voltage output circuit 401 outputs a 15V direct current voltage. When the output end of the first comparator 601 of the short circuit judgment circuit 402 is a low level signal, it indicates that the voltage of the output end of the argon arc welding body 405 is greater than 5V, and it is determined that the tungsten needle of the argon arc welding body 405 is not in contact with the workpiece. Since the output end of the first comparator 601 is a low level signal, the output end UT of the current regulator 403 does not output (i.e., the output control voltage is 0V), and the PWM control signal output end of the current module PWM controller 701 does not output the PWM control signal. At this time, the main circuit of the argon arc welding body 405 does not output. When the output end of the first comparator 601 of the short circuit judgment circuit 402 is a high level signal, it indicates that the voltage of the output end of the argon arc welding body 405 is less than 5V, and it is determined that the tungsten needle of the argon arc welding body 405 is in contact with the workpiece. Since the output end of the first comparator 601 is a high level signal, the output end UT of the current regulator 403 and +15V begin to charge the charging capacitor 610, and the output end UT of the current regulator 403 begins to output. Since the charging capacitor 610 has a certain charging time, the control voltage output by the output end UT of the current regulator 403 gradually increases from 0V to the normal output. The time is about 5ms, and the control voltage increases to the normal output, indicating that the charging of the charging capacitor 610 is completed. The duty cycle of the PWM control signal output by the PWM control signal output end of the current module PWM controller 701 gradually increases from 0 to the duty cycle corresponding to 10A. The time is greater than 2ms, and the current output by the main circuit of the argon arc welding body 405 to the output end gradually increases from 0A to 10A, so that overshoot does not occur. Figure 9 Figure 9 In the figure, 901 is the voltage waveform of the pull-arc argon arc welding, 902 is the current waveform of the pull-arc argon arc welding, 903 is the waveform of the control voltage output by the output end UT of the current regulator 403, 904 is the waveform of the PWM control signal output by the PWM control signal output end (PWM-A / B) of the current module PWM controller 701, and 905 is the output current waveform of the argon arc welding.

[0060] The first argon arc welding device is provided in the second embodiment, which comprises an argon arc welding body and an argon arc welding pull-arc anti-sticking device. The argon arc welding pull-arc anti-sticking device has been described in detail in the above-mentioned argon arc welding pull-arc anti-sticking device embodiment one, and will not be repeated here. ​

[0061] The second embodiment provides a second argon arc welding device, comprising: an argon arc welding body and an argon arc welding pulling arc starting anti-sticking device. Since the argon arc welding pulling arc starting anti-sticking device has been described in detail in the above-mentioned second embodiment of the argon arc welding pulling arc starting anti-sticking device, it will not be repeated here.

[0062] The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A device for preventing sticking during argon arc welding, characterized in that, The application relates to an auxiliary voltage output circuit for an argon arc welding body, a short circuit judging circuit and a current adjusting circuit. The auxiliary voltage output circuit is used for outputting a preset direct current voltage to an output end of the argon arc welding body. The short circuit judging circuit is used for detecting the voltage of the output end of the argon arc welding body to judge whether the tungsten needle of the argon arc welding body is in contact with a workpiece. The current adjusting circuit is connected with the output end of the short circuit judging circuit, and is used for outputting a control signal for increasing the current outputted by the output end of the argon arc welding body from zero when the tungsten needle of the argon arc welding body is not in contact with the workpiece. The short circuit judging circuit comprises a first comparator, the non-inverting input end of the first comparator is used for inputting a preset reference voltage, the inverting input end of the first comparator is connected with the output end of the argon arc welding body, and the output end of the first comparator outputs a judging signal used for judging whether the tungsten needle of the argon arc welding body is in contact with the workpiece according to the level of the judging signal. The current adjusting circuit comprises a current regulator, a unidirectional conducting device and a PWM controller, the short circuit judging circuit further comprises a charging capacitor and a pull-up resistor, one end of the charging capacitor is connected with the output end of the first comparator, the other end of the charging capacitor is grounded, the output end of the first comparator is connected with a power supply through the pull-up resistor, the output end of the current regulator is connected with the input end of the unidirectional conducting device and the input end of the PWM controller, the output end of the unidirectional conducting device is connected with the output end of the first comparator, and the output end of the PWM controller is used for outputting a corresponding PWM control signal. The auxiliary voltage output circuit comprises a rectifier, a power supply switch, a relay and a power supply circuit, the direct current side of the rectifier is connected with one end of the contact switch of the relay, the other end of the contact switch of the relay is used for connecting the output end of the argon arc welding body, and the power supply switch and the control coil of the relay are arranged in series in the power supply circuit.

2. The argon arc welding lift-off arc starting anti-sticking device according to claim 1, characterized in that, The power supply switch is an electrically-controlled electronic switch device.

3. The argon arc welding lift-off arc starting anti-sticking device according to claim 2, characterized in that, The short circuit judging circuit further comprises a first operational amplifier and a second operational amplifier, the input end of the first operational amplifier is used for inputting the preset reference voltage, and the output end of the first operational amplifier is connected with the non-inverting input end of the first comparator; the input end of the second operational amplifier is connected with the output end of the argon arc welding body, and the output end of the second operational amplifier is connected with the inverting input end of the first comparator.

4. The argon arc welding lift arc anti-stick device according to claim 1, characterized in that, The current regulator is a current PI regulator.

5. The argon arc welding lift arc anti-stick device of claim 1, wherein, The current PI regulator comprises a second operational amplifier, the inverting input end of the second operational amplifier is used for inputting a current given signal and a current feedback signal, the non-inverting input end of the second operational amplifier is grounded, and the output end of the second operational amplifier is connected with the input end of the PWM controller.

6. The argon arc welding lift arc stick prevention device of claim 5, wherein, ​ 7. The argon arc weld pull start anti-stick device of claim 6, wherein, The current PI regulator further comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second capacitor, one end of the first resistor is connected to the inverting input terminal of the second operational amplifier, the other end of the first resistor is used to access the current given signal, one end of the second resistor is connected to the inverting input terminal of the second operational amplifier, the other end of the second resistor is used to access the current feedback signal, the third resistor and the first capacitor are connected in series to form a series branch, one end of the series branch is connected to the inverting input terminal of the second operational amplifier, the other end of the series branch is connected to the output terminal of the second operational amplifier; the output terminal of the second operational amplifier is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is grounded, the connection point of the fourth resistor and the fifth resistor is connected to the input terminal of the unidirectional conduction device and the input terminal of the PWM controller, and the fifth resistor is connected in parallel with the second capacitor.

8. An argon arc welding apparatus characterized by comprising: It comprises: an argon arc welding body; and the argon arc welding pulling arc starting anti-sticking device according to any one of claims 1-7. ​

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