CN115229309A

CN115229309A - TIG alternating current welding method with adjustable three frequencies

Info

Publication number: CN115229309A
Application number: CN202210826991.3A
Authority: CN
Inventors: 张建民; 王基尧; 赵克勇
Original assignee: Shanghai Duomu Industry Co ltd
Current assignee: Shanghai Duomu Industry Co ltd
Priority date: 2022-07-14
Filing date: 2022-07-14
Publication date: 2022-10-25
Anticipated expiration: 2042-07-14
Also published as: CN115229309B

Abstract

The invention discloses a TIG alternating current welding method with adjustable three frequencies, which is characterized in that before welding, a control panel of a TIG alternating current welding machine with adjustable three frequencies is used for independently adjusting or combining and adjusting main frequency, carrier frequency and ripple frequency; in the welding process, fine adjustment is carried out on the main frequency, the carrier frequency and the ripple frequency according to the welding waveform; before welding begins, firstly, sequentially selecting three frequencies on a control panel; secondly, setting and adjusting initial parameters of the selected frequency to be adjusted; and finally, after the initial parameters of the three frequencies are adjusted, starting a welding machine for welding. The three frequency-adjustable welding methods provided by the scheme enable the carrier frequency to be fully adjustable between 20KHZ and 200KHZ, enhance the fusion depth of aluminum welding, increase the stirring of a welding bead molten pool, reduce air holes, enhance welding bead cleaning and realize the performance improvement of aluminum welding.

Description

TIG alternating current welding method with adjustable three frequencies

Technical Field

The invention belongs to the field of alternating current TIG welding, and particularly relates to three frequency-adjustable TIG alternating current welding methods.

Background

When non-ferrous metals such as TIG aluminum and the like are welded, the following three difficulties always exist:

1. due to the low melting point of aluminum (the melting point is 660 ℃), the welding process is softened seriously;

2. the surface is wrapped with a high-melting-point oxide film (Al 2O3 with the melting point of 2060 ℃) and is difficult to melt;

3. air holes are easy to be generated in the welding process.

Although people adopt the method of alternating-current square wave welding, the problems are solved to a certain extent, and particularly, the problems of air holes, shallow welding fusion depth and the like exist on medium-thickness plate aluminum welding. The key to solve these problems is to control the output mode of the welding current, and then to control the shape of the arc, and to change the welding effect.

The current state of the welding equipment is as follows:

1, the common AC welding power supply can only adjust the main frequency and the duty ratio, and the main frequency 1/T1 frequency range of the graph 1 is 50-150HZ.

2, the individual high-end power supply can adjust 1/T2 of the carrier frequency diagram 1, the frequency range is 0.1-10KHZ, but the adjustment range is too wide when in use, the frequency ranges are difficult to independently adjust, the frequencies are mutually influenced, and the noise of the electric arc is too large when the frequency is high, so the use is influenced.

3, the current ripple frequency 1/T3 of the welding power supply is fixed.

In practical welding, it is significant to change the current ripple, which can effectively change the arc shape, and the inductance or the operating frequency of the power source should be changed in order to change the current ripple, but there are the following difficulties:

a, difficulty in changing the working frequency of a power supply: because the current welding current is determined by a primary inverter power supply, the working frequency of a high-power supply is generally fixed at a certain frequency, such as 20KHZ or 100KHZ, due to the limitation of a transformer and filter inductance. Once the operating frequency is changed, the transformer or inductor is newly designed. Which is not possible in practical use.

B. Difficulty in changing the inductance: the control difficulty of adjusting the inductance is very high, (the inductance is formed by winding a magnetic bar, the number of turns of a coil or an air gap of an iron core needs to be changed when the inductance is changed, but the two items are fixed after the inductance is formed and are difficult to adjust).

In summary, it is difficult to achieve the desired welding effect using the existing equipment.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the welding method is provided, and the problem that ripples of welding equipment in the prior art are not adjustable is solved.

The invention adopts the following technical scheme for solving the technical problems:

in the TIG alternating current welding method with adjustable frequency, the current output waveform of alternating current welding is a composite waveform and consists of main frequency, carrier frequency and ripple frequency; before welding, independently adjusting parameter setting or combined adjusting parameter setting is carried out on main frequency, carrier frequency and ripple frequency through a control system of three frequency-adjustable TIG (tungsten inert gas) alternating current welding machines; and in the welding process, the main frequency, the carrier frequency and the ripple frequency are finely adjusted according to the requirements of the welding state.

The output waveform of the welding current comprises three combinations of 'main frequency + carrier frequency + ripple frequency', 'main frequency + carrier frequency' and 'main frequency + ripple frequency'.

The specific adjustment method is as follows:

before welding starts, firstly, performing conventional function selection on a welding machine; then, setting welding parameters, including welding output frequency setting, and respectively selecting and setting parameters of the main frequency, the carrier frequency and the ripple frequency;

during welding, any one or combination of the three frequencies is selected and parameter adjusted according to welding state requirements.

Through different welding parameter combinations, the fusion depth change, the width change of a welding bead and the change of the oxide film breaking capacity of a welding machine are realized, and the welding forming effect is changed.

The frequency range of the main frequency is 100-250HZ.

The frequency range of the carrier frequency is 100-1000Hz.

The frequency range of the ripple frequency is 20KHZ-100KHZ.

And a control panel of the control system is provided with a combined knob which can respectively select and set corresponding frequency parameters.

The setting parameters of the three frequencies comprise frequency and duty ratio.

Compared with the prior art, the invention has the following beneficial effects:

1. the three frequency-adjustable welding methods provided by the scheme enable the carrier frequency to be fully adjustable between 20KHZ and 200KHZ, enhance the fusion depth of aluminum welding, increase the stirring of a welding bead molten pool, reduce air holes, enhance welding bead cleaning and realize the performance improvement of aluminum welding.

2. During TIG alternating current welding, the frequency (1/T2) and the proportion of the carrier frequency are adjusted, so that the stiffness of the electric arc can be changed, and the electric arc is more concentrated; and allows it to be independently tuned and used simultaneously with other pulses, such as using a carrier frequency on a low frequency pulse wave.

3. During TIG alternating current welding, the ripple frequency (1/T3) is adjusted, the fluidity of a metal welding bead can be increased, bubbles in the welding bead can be removed, and the welding quality is improved.

Drawings

Fig. 1 is a three-frequency waveform diagram of a welding device in the prior art.

Fig. 2 is a schematic diagram of waveforms for adjusting the main frequency and the carrier frequency according to the present invention.

Fig. 3 is a schematic diagram of the arc characteristic waveform for adjusting the ripple frequency according to the present invention.

FIG. 4 is a block diagram of the welding system components of the present invention.

Wherein the circles on the waveform diagram represent indicator lights.

Detailed Description

In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments.

All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort shall fall within the protection scope of the present application.

The purpose of the present application is to overcome the deficiencies of the prior art, and develop three welding methods with adjustable frequency, so that the ripple frequency in the welding method can be fully adjusted between 20KHZ and 100KHZ while the main ac frequency is adjusted, and the carrier frequency can be adjusted between 100 HZ and 1000HZ.

In order to allow the frequencies to be adjusted independently and not to be confused with each other, we newly define the range and name of the frequencies, separate the low frequency pulses from the carrier frequency, define the pulses of 0-10HZ as the base frequency and not discuss here, the frequency of the ac waveform is named as the main frequency 100-250HZ, the waveform variation added to the main frequency is named as the carrier frequency 100-1000HZ, and the frequency generated by the high frequency adjustment is named as the ripple frequency 20-100 KHZ.

The adjustment range of the carrier frequency is set to be in the range of 100-1000HZ in the present application, and can be used simultaneously with a lower frequency (i.e., low frequency pulse), and is separated for a low frequency portion which is not set in the adjustment range to be used independently, and is removed for a high frequency portion of 1-10KHZ, because the arc noise in this high frequency portion is very large during welding and welding cannot be performed.

In the welding process, the frequency is a very important adjusting parameter, different frequencies are needed during welding, particularly, alternating current welding is needed for welding aluminum, the main frequency range of the alternating current is 50-250HZ, the adjustment is needed, the fusion depth of an electric arc can be changed, and the positive and negative symmetry of the alternating current pulse width can be adjusted, so that the cleaning of an oxide film is facilitated.

Theories and practices prove that the stiffness of the current can be changed by adding the current carrier frequency of the pulse change of 200-1000HZ to the amplitude change of the welding current, so that the electric arc is more concentrated, and the melting characteristics of the electric arc are different due to the change of the frequency and the amplitude of the current ripple wave above 20KHZ, so that the welding of the thin plate is facilitated.

The frequency conversion technology is a difficult point in the field, and the traditional power supply does not need frequency conversion to adjust current ripples, because the traditional high-precision welding power supply has a plurality of power supplies, which are generally inverter power supplies, the inverter power supply has the advantages of good dynamic characteristic, high efficiency, small volume and light weight, but the working frequency of the inverter power supply is fixed, once the working frequency is changed, the transformer, the input filter capacitor, the output inductor and the power element of the inverter power supply are all changed, so that the pulse width modulation technology with fixed frequency can be generally used, and the change of carrier frequency can cause the current change of the inverted transformer to be severe, thereby easily causing the magnetic core of the transformer of the inverter power supply to be saturated, the current to be out of control and the efficiency to be reduced. Therefore, the frequency conversion of the welding power supply is very easy to say, the difficulty in making is very great, and the method is a difficult problem to be solved urgently in the field.

The solution, key technology and existing problems of the frequency conversion technology mainly include the following aspects:

in order to change the frequency of the current, direct control needs to be carried out on a welding load, intermediate links are reduced as much as possible, power elements which are needed generally need to be small in conduction voltage drop, high in switching frequency and strong in spike voltage resistance, the elements are difficult to drive, the cost is high, for example, the frequency of an IGBT is not enough, the loss is extremely large when the IGBT works at 100KHZ, and silicon carbide is expensive, especially large-current elements. However, when the current of the field effect transistor is large enough, the withstand voltage is significantly reduced, and the absorption circuit is extremely difficult to design. The parallel technology has high requirement.

Therefore, in order to solve the problem of the frequency conversion technology, the present application adopts a soft switching absorption technology, which is a regulation technology applied to a power switching tube in power electronics, and by using the technology, the power loss and the electromagnetic interference of a hard switching tube can be reduced. And reduces the voltage spike of the power tube.

The voltage spike can be reduced when the large current is cut off, the loss can be reduced, and the low-voltage field effect transistor can be used for operation.

In order to adjust the ripple current, a secondary control mode is adopted to directly adjust the current of the load instead of adjusting the welding current through the transformer in one time, so that the influence of transformer saturation can be removed.

In order to change the waveform rapidly, the main control panel carries out secondary alternating current sampling real-time control.

The scheme is a welding power supply control method, and welding quality is improved by adding three frequency modes for adjusting the current waveform of the welding power supply. For ease of explanation, the three frequencies are defined herein as the primary frequency, carrier frequency and ripple frequency. The key point of the invention is that 'main frequency + carrier frequency + ripple frequency' is independently adjustable and is combined for use.

In the TIG alternating current welding method with adjustable frequency, the current output waveform of alternating current welding is a composite waveform and consists of main frequency, carrier frequency and ripple frequency; before welding, independently adjusting or combining main frequency, carrier frequency and ripple frequency by a control system of three frequency-adjustable TIG alternating current welding machines; and in the welding process, the main frequency, the carrier frequency and the ripple frequency are finely adjusted according to the requirements of the welding state.

The specific adjustment method is as follows:

Specific embodiment, as shown in figures 2, 3 and 4,

the embodiment is described by taking the control panel as shown in the figure as an example, and the control panel can be various, as long as the control adjustment can be realized, and the control panel is not limited to the form described in the embodiment.

Before welding, independently adjusting or combining and adjusting main frequency, carrier frequency and ripple frequency through a control panel of a three-frequency adjustable TIG AC welding machine; in the welding process, fine adjustment is carried out on the main frequency, the carrier frequency and the ripple frequency according to the welding waveform; the control panel of the alternating current welding machine comprises a button and a knob which are arranged by an integral key, the frequency to be adjusted is selected through the button, and initial parameters and working parameters of the selected frequency are set and adjusted through the knob; the control panel is provided with two integrated keys, namely an integrated key A and an integrated key B, wherein the integrated key A is used for adjusting the main frequency and the carrier frequency, and the integrated key B is used for adjusting the high-frequency ripple.

The control panel comprises a three-frequency status indicator lamp, wherein the main frequency status indicator lamp comprises a main frequency indicator lamp and a main frequency duty ratio D1 indicator lamp; the carrier frequency state indicator lamp comprises a carrier frequency indicator lamp, an output current indicator lamp and a carrier frequency duty ratio D3 indicator lamp, and the output current indicator lamp comprises a welding current base value (or valley value) indicator lamp and a welding current peak value indicator lamp; the ripple frequency includes an arc characteristic indicator light;

the specific regulation method is as follows:

before welding begins, firstly, sequentially selecting three frequencies on a control panel; selection as main frequency regulation: pressing the button of the integral key A lights the main frequency duty ratio D1 indicator, rotating the knob to turn D1 to a preset value, then pressing the button of the integral key A lights the main frequency indicator, and rotating the knob to turn the main frequency to the preset value.

Carrier frequency adjustment is selected as follows: pressing the button of the integrated key A to turn on the welding current peak value IA indicator light, rotating the knob to turn IA to a preset value, then pressing the button of the integrated key A to turn on the welding current basic value IC indicator light, rotating the knob to turn IC to a preset value, (normally making IC < IA), then pressing the button of the integrated key A to turn on the carrier frequency duty ratio D3 indicator light, rotating the knob to turn carrier frequency duty ratio D3 to a preset value, then pressing the button of the integrated key A to turn on the carrier frequency indicator light, rotating the knob to turn the carrier frequency to a preset value (200-1000 HZ), if the arc stiffness is required to be large, the difference between IC and IA is larger, the carrier frequency duty ratio is below 50%, and the carrier frequency is higher.

High-frequency ripple regulation: pressing the button of the integral key B to turn on the arc characteristic indicator lamp and then rotating the integral key B can adjust the ripple output of the power supply, wherein 20 corresponds to 20KHZ and 200 corresponds to 200KHZ.

And finally, after the initial parameters of the three frequencies are adjusted, starting the welding machine to perform welding operation.

During welding, any one or any combination of the three frequencies is selected and parametrically adjusted on a control panel based on the results of the welding output.

The three frequencies are selectively adjusted by using independent buttons and knobs, or the buttons and the knobs are combined randomly to share time-sharing adjustment.

The dominant frequency is 1/T1, and the adjusting range is 50-150HZ; carrier frequency is 1/T2, and the adjusting range is 100-1000HZ; the ripple frequency is 1/T3, the adjusting range is 20KHZ-100KHZ, and in the same working period, T1 is more than T2 and more than T3.

The welder using this scheme includes seven units, respectively:

1. the voltage reduction system is used for reducing the three-phase 380V voltage to the no-load voltage of the welding power supply, and adopts two modes, namely a three-phase transformer and a rectifier bridge; one uses high frequency inverter. The unit does not regulate current and is not a key technical point of the power supply.

2. The low-voltage frequency conversion current regulating unit is a core component of the technology, adopts two high-frequency current converting modules, uses a soft absorption technology, and can work from low frequency to high frequency to realize high-current low-loss work within 400A.

3. A filtering arc striking unit: in the unit, the waveform modulated by the low-voltage frequency conversion current regulating unit is filtered and absorbed, and is synthesized with an arc stabilizing signal generated by an arc stabilizing plate, and finally the synthesized signal is output to a welding gun and a workpiece through an arc striking coil.

4. A drive circuit: the driving signal generated by the main control board is isolated and amplified, and then the two modules of the low-voltage frequency conversion current regulating unit are driven, and the unit can drive four 800A and 250V MOS devices to work under 100KHZ.

5. The working time sequence parameter setting system stores the parameters set on the panel and sends the parameters to the main control panel through the communication port, and the system consists of a digital display, a CPU, a dial switch, a key and a communication chip and is a display operation system of the power supply.

6. Main control board: the unit is the core of the whole power supply, a main control board CPU translates a time sequence parameter of a system into an executable signal after receiving the executable signal through a 485 communication port, the executable signal is transmitted to an operational circuit through a conversion circuit, the operational circuit transmits an operational result to a variable-frequency current regulation driving circuit through numerical values of the operational conversion circuit and a signal processing circuit, the variable-frequency current regulation driving circuit converts the signal and outputs the signal to a driving board, the other path of signal of a single chip microcomputer and the signal of the signal processing unit are synthesized through a signal synthesis circuit, then the signal is distributed to an arc stabilizing driving circuit, and then the signal is transmitted to an arc stabilizing board.

7. Arc stabilization control panel: the main board is controlled jointly according to the current feedback signal and the CPU setting signal to generate an arc stabilizing driving pulse, the arc stabilizing driving pulse is transmitted to the arc stabilizing board through the port, the arc stabilizing board amplifies the driving pulse to generate two groups of high-voltage heavy current pulses, and the two groups of high-voltage heavy current pulses are directly combined with the 70 inverter main power circuit to drive a welding load.

The working principle and the working process of the welding machine are as follows:

three-phase voltage is rectified and filtered by a transformer or an inverter power supply in a voltage reduction system unit, the voltage is reduced to about 70V direct current, then the current is regulated into three welding waveforms with adjustable frequencies by a power tube used for a low-voltage variable-frequency current regulation unit, and then the welding waveforms are output to a welding gun workpiece for welding by a circuit of a filtering arc stabilization unit, a setting parameter on a panel is transmitted to a main control panel unit by a working time sequence parameter setting system unit through 485 communication, the main control panel can generate a dynamic signal according to a feedback signal IF and communication data of the working time sequence parameter setting system and transmit the dynamic signal to a driving circuit, the driving circuit unit generates a driving signal to drive the low-voltage variable-frequency current regulation, and directly drives an arc stabilization control panel to generate an arc stabilization signal to enter welding through a filtering arc striking unit.

The method is applied to welding, the penetration of aluminum welding is enhanced, the stirring of a welding bead molten pool is increased, air holes are reduced, the welding bead cleaning is enhanced, and the performance improvement of the aluminum welding can be realized.

It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the description and claims of this application and the above-described drawings, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings. These terms are used primarily to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation.

Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meaning of these terms in this application will be understood by those of ordinary skill in the art as the case may be.

Furthermore, the terms "mounted," "disposed," "provided," "connected," and "coupled" are to be construed broadly. For example, it may be a fixed connection, a removable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict.

It is well within the skill of those in the art to implement, without further elaboration, the claimed subject matter contemplates improvements to tri-band tuning methods.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Three frequency-adjustable TIG alternating current welding methods are characterized in that: the current output waveform of the alternating current welding is a composite waveform and consists of a main frequency, a carrier frequency and a ripple frequency; before welding, independently adjusting or combining main frequency, carrier frequency and ripple frequency by a control system of three frequency-adjustable TIG alternating current welding machines; and in the welding process, the main frequency, the carrier frequency and the ripple frequency are finely adjusted according to the requirements of the welding state.

2. Three frequency-adjustable TIG alternating current welding methods of claim 1, wherein: the output waveform of the welding current comprises three combinations of 'main frequency + carrier frequency + ripple frequency', 'main frequency + carrier frequency' and 'main frequency + ripple frequency'.

3. A TIG alternating current welding method with three adjustable frequencies according to claim 2, characterized in that: the specific regulation method is as follows:

4. A TIG alternating current welding method with three adjustable frequencies according to claim 3, characterized in that: through different welding parameter combinations, the fusion depth change, the width change of a welding bead and the change of the oxide film breaking capacity of a welding machine are realized, and the welding forming effect is changed.

5. A TIG alternating current welding method with three adjustable frequencies according to claim 1, characterized in that: the frequency range of the main frequency is 100-250HZ.

6. A TIG alternating current welding method with three adjustable frequencies according to claim 1, characterized in that: the frequency range of the carrier frequency is 100-1000HZ.

7. A TIG alternating current welding method with three adjustable frequencies according to claim 1, characterized in that: the frequency range of the ripple frequency is 20KHZ-100KHZ.

8. A TIG alternating current welding method with three adjustable frequencies according to claim 1, characterized in that: and a control panel of the control system is provided with a combined knob which can respectively select and set corresponding frequency parameters.

9. Three frequency-adjustable TIG alternating current welding methods according to any of claims 1 to 8, characterized in that: the setting parameters of the three frequencies comprise frequency and duty ratio.