Wire feeding control circuit and laser welding system

Abstract

The invention discloses a wire feeding control circuit and a laser welding system. A driving module of the circuit comprises H-bridge driving circuits in one-to-one correspondence with windings of a bipolar stepping motor; the H-bridge driving circuit comprises a plurality of bridge arms; each bridge arm comprises a corresponding switch element; a first node between the first upper bridge arm and the first lower bridge arm is connected with the first end of the corresponding winding; a second node between the second upper bridge arm and the second lower bridge arm is connected with a second end of the corresponding winding; the first end of the switching element of the first upper bridge arm is connected with a first power supply; the second end of the switch element of the first upper bridge arm is connected with the first end of the switch element of the first lower bridge arm; the second end of the switch element of the first lower bridge arm is connected with a first ground end through a sampling resistor. According to the technical scheme provided by the invention, reliable wire breaking of the welding wire can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a wire feeding control circuit and a laser welding system. Background Art

[0002] Laser welding is a highly efficient and precise welding method that utilizes a high-energy-density laser beam as a heat source. It is a key application of laser material processing technology. In the 1970s, it was primarily used for welding thin-walled materials and low-speed welding. The welding process is heat-conduction-based. Specifically, laser radiation heats the workpiece surface, which then diffuses into the interior through heat conduction. By controlling parameters such as the laser pulse width, energy, peak power, and repetition rate, the workpiece is melted, forming a specific molten pool.

[0003] In the wire feeding welding process of the existing technology, the automatic wire breaking operation of laser welding is achieved by reversely retracting the wire feeding wheel. Before the high energy density of the laser forms a molten pool and the molten pool quickly crystallizes and fuses, the wire feeding wheel is reversely retracted to quickly pull the welding wire out of the molten pool, avoiding the welding wire from remaining in the molten pool or fusing with the workpiece surface, thereby achieving the purpose of automatic wire breaking.

[0004] However, in the actual implementation process, users are prone to "deliberately" pushing the gun and other operations, which may cause the welding wire to not break normally, and dragging may occur on the outside of the weld, causing the welding material to stick, affecting the welding appearance, and also affecting the welding effect and the operator's operating efficiency, causing inconvenience in actual use. Summary of the Invention

[0005] The embodiments of the present invention provide a wire feeding control circuit and a laser welding system to achieve normal wire breaking and improve operation efficiency.

[0006] In a first aspect, an embodiment of the present invention provides a wire feeding control circuit, comprising: a bipolar stepping motor, a drive module, and a control chip;

[0007] The driving module includes an H-bridge driving circuit arranged in a one-to-one correspondence with the windings of the bipolar stepping motor; the H-bridge driving circuit includes a plurality of bridge arms; each of the bridge arms includes a corresponding switching element; a first upper bridge arm is electrically connected to a first lower bridge arm; a second upper bridge arm is electrically connected to a second lower bridge arm; a first node between the first upper bridge arm and the first lower bridge arm is connected to a first end of a corresponding winding; and a second node between the second upper bridge arm and the second lower bridge arm is connected to a second end of the corresponding winding;

[0008] The first end of the switching element of the first upper bridge arm is connected to the first power supply; the second end of the switching element of the first upper bridge arm is connected to the first end of the switching element of the first lower bridge arm; the second end of the switching element of the first lower bridge arm is connected to the first ground end through the sampling resistor.

[0009] In a second aspect, an embodiment of the present invention further provides a laser welding system, comprising a single chip microcomputer, a communication chip, a laser host, and a wire feeding control circuit provided by any embodiment of the present invention;

[0010] The single chip microcomputer is connected to the laser host through the communication chip and is used to write the rotation state of the bipolar stepping motor to the laser host;

[0011] The single chip microcomputer is electrically connected to the wire feeding control circuit and is used for sending an enable signal and a control signal to the wire feeding control circuit.

[0012] In the present invention, a bipolar stepper motor is used in the wire feeding control circuit to feed the welding wire and retract the broken wire. The wire feeding control circuit also includes a driving module and a control chip. The driving module includes an H-bridge driving circuit arranged in a one-to-one correspondence with the windings of the bipolar stepper motor. The H-bridge driving circuit includes a first upper bridge arm, a first node and a first lower bridge arm connected in sequence, and a second upper bridge arm, a second node and a second lower bridge arm connected in sequence. A corresponding winding is connected between the first node and the second node, and each bridge arm includes a corresponding switching element. The first end of the first upper bridge arm is connected to the first power supply, and the second end is connected to the first end of the first lower bridge arm; the second end of the first lower bridge arm is connected to the first ground end through a sampling resistor. This embodiment uses a bipolar stepper motor to realize wire feeding and wire drawing, so that the wire feeding and wire drawing speeds are stable, which facilitates the precise control of normal wire breakage of the welding wire, avoids the dragging phenomenon at the welding point, and improves operating efficiency. The sampling resistor is connected in series in the H-bridge drive circuit to detect the current driving the bipolar stepper motor, so as to adjust the output signal of the drive module, realize the smooth and precise stop of the bipolar stepper motor, and avoid the oscillation or stall of the bipolar stepper motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic structural diagram of a wire feeding control circuit provided by an embodiment of the invention;

[0014] Figure 2 A schematic structural diagram of another wire feeding control circuit provided by an embodiment of the present invention;

[0015] Figure 3 A schematic diagram of a standard pulse signal provided by an embodiment of the present invention;

[0016] Figure 4 Schematic diagram of output signals of a wire feeding control circuit in the prior art;

[0017] Figure 5 A schematic structural diagram of another wire feeding control circuit provided by an embodiment of the present invention;

[0018] Figure 6 A schematic structural diagram of a power supply module provided in an embodiment of the present invention;

[0019] Figure 7 A schematic structural diagram of a laser welding system provided in an embodiment of the present invention.

[0020] Explanation of the accompanying symbols: 11-bipolar stepper motor, 12-drive module, 121-H-bridge drive circuit, 122-control unit, 123-pull-down unit, 124-bootstrap unit, 13-control chip, 14-power supply module, 141-first upper bridge arm, 142-first lower bridge arm, 143-second upper bridge arm, 144-second lower bridge arm, 145-switching element, 15-filtering unit, 21-single-chip microcomputer, 22-communication chip, 23-laser host, 24-wire feeding control circuit. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0022] To quickly retract the welding wire from the molten pool and prevent wire breakage, a retraction speed of greater than 100 mm / s is required. This speed is sufficient for basic wire breakage. Existing handheld laser welding systems use a brushed DC motor as the drive motor for the wire feeder. The core of a brushed DC motor is to dynamically switch the current direction through brushes and a commutator, ensuring a continuous unidirectional electromagnetic force on the rotor winding, thereby achieving stable operation. Its simple structure and low cost make it widely used in many basic scenarios.

[0023] However, in the process of implementing this application, the inventors discovered that the use of a brushed DC motor as a drive motor in a handheld laser welding system presents the following problems: the brushes have a lifespan issue and require regular replacement, and sparks are easily generated at high speeds. Currently, when the speed of a brushed DC motor is increased, polarization occurs, and the motor is prone to unstable speed, resulting in inconsistent wire feeding and poor welding results. For example, when the wire feed speed is adjusted to 5-30 mm / s and the retraction speed is adjusted to 140 mm / s, if the wire feed speed is stable, the retraction speed will be unstable, varying between fast and slow; if the retraction speed is stable, the wire feed speed will be unstable, varying between fast and slow.

[0024] In order to solve the above problems, the embodiment of the present invention replaces the DC brushed motor with a bipolar stepper motor as the drive motor. A stepper motor is a special motor that converts an electrical pulse signal into angular displacement or linear displacement. Its characteristic is that the rotation angle and speed of the motor can be accurately controlled by controlling the number, frequency and direction of the input pulses. The gear sets differ by 1.8° and rotate the corresponding angle according to the number of pulses, which can accurately achieve wire feeding and high-speed wire breaking. Each winding of the bipolar stepper motor can be energized in two directions, so one end of each winding can be either the N pole or the S pole. The embodiment of the present invention uses a bipolar stepper motor as the drive motor of the wire feeder to increase the retraction speed to 160 mm / s, and the above-mentioned problem of unstable wire feeding or retraction speed will not occur.

[0025] Figure 1 A schematic diagram of a wire feeding control circuit according to an embodiment of the invention is provided. Figure 2 Schematic diagram of another wire feeding control circuit provided by an embodiment of the present invention. An embodiment of the present invention provides a wire feeding control circuit, such as Figure 1 As shown, it includes: a bipolar stepping motor 11, a driving module 12 and a control chip 13;

[0026] The driving module 12 includes an H-bridge driving circuit 121 arranged in a one-to-one correspondence with the windings of the bipolar stepper motor 11; the H-bridge driving circuit 121 includes multiple bridge arms; each bridge arm includes a corresponding switching element 145; the first upper bridge arm 141 and the first lower bridge arm 142 are electrically connected; the second upper bridge arm 143 and the second lower bridge arm 144 are electrically connected; the first node N1 between the first upper bridge arm 141 and the first lower bridge arm 142 is connected to the first end of the corresponding winding; the second node N2 between the second upper bridge arm 143 and the second lower bridge arm 144 is connected to the second end of the corresponding winding; the first end of the switching element 145 of the first upper bridge arm 141 is connected to the first power supply V1; the second end of the switching element 145 of the first upper bridge arm 141 is connected to the first end of the switching element 145 of the first lower bridge arm 142; the second end of the switching element 145 of the first lower bridge arm 144 is connected to the first ground terminal GNDM through the sampling resistor R50.

[0027] In an embodiment of the present invention, a bipolar stepper motor is used in a wire feeding control circuit to feed the welding wire and retract the wire to prevent wire breakage. The wire feeding control circuit also includes a drive module and a control chip. The drive module includes an H-bridge drive circuit that is arranged in a one-to-one correspondence with the windings of the bipolar stepper motor. The H-bridge drive circuit includes a first upper bridge arm, a first node, and a first lower bridge arm connected in sequence, and a second upper bridge arm, a second node, and a second lower bridge arm connected in sequence. A corresponding winding is connected between the first node and the second node, and each bridge arm includes a corresponding switching element. The first end of the first upper bridge arm is connected to the first power supply, and the second end is connected to the first end of the first lower bridge arm; the second end of the first lower bridge arm is connected to the first ground end through a sampling resistor. This embodiment uses a bipolar stepper motor to achieve wire feeding and wire retraction, so that the wire feeding and wire retraction speeds are stable, which facilitates the precise control of normal wire breakage of the welding wire, avoids dragging at the welding point, and improves operating efficiency. In addition, the sampling resistor is connected in series in the H-bridge drive circuit to detect the current driving the bipolar stepper motor, so as to adjust the output signal of the drive module, realize the smooth and precise stopping of the bipolar stepper motor, and avoid the oscillation or stall of the bipolar stepper motor.

[0028] The above is the core concept of the present invention. The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] like Figure 2 As shown, Figure 2This embodiment provides an H-bridge drive circuit 121 for a wire feeding control circuit. This embodiment uses a dual H-bridge drive circuit as an example for illustrating a bipolar stepper motor 11. Specifically, the H-bridge drive circuit 121 corresponds to each winding of the bipolar stepper motor 11. An H-bridge drive circuit 121 includes multiple bridge arms. For example, each H-bridge drive circuit 121 may include four bridge arms, with the multiple bridge arms including at least a first upper bridge arm 141, a first lower bridge arm 142, a second upper bridge arm 143, and a second lower bridge arm 144. In this embodiment, the first power supply V1, the first upper bridge arm 141, the first node N1, the first lower bridge arm 142, and the first ground terminal GNDM are electrically connected in sequence. The first power supply V1, the second upper bridge arm 143, the second node N2, the second lower bridge arm 144, and the first ground terminal GNDM are electrically connected in sequence. The first node N1 is electrically connected to the first end of the corresponding winding, and the second node N2 is electrically connected to the second end of the corresponding winding. Optionally, the first end of the switch element 145 of the first upper bridge arm 141 is connected to the first power supply V1; the second end of the switch element 145 of the first upper bridge arm 141 is connected to the first end of the switch element 145 of the first lower bridge arm 142; the second end of the switch element 145 of the first lower bridge arm 142 is connected to the first ground terminal GNDM via the sampling resistor R50. Similarly, the first end of the switch element 145 of the second upper bridge arm 143 is connected to the first power supply V1; the second end of the switch element 145 of the second upper bridge arm 143 is connected to the first end of the switch element 145 of the second lower bridge arm 144; and the second end of the switch element 145 of the second lower bridge arm 144 is connected to the first ground terminal GNDM. Exemplarily, the first power supply V1 can be 24V. Optionally, the second end of the switch element 145 of the first lower bridge arm 142 is connected to the second end of the switch element 145 of the second lower bridge arm 144. It should be noted that the sampling resistor R50 is connected in series in the H-bridge drive circuit 121, and can be set between the second end of the switching element 145 of the first lower bridge arm 142 and the first ground terminal GNDM, or between the second end of the switching element 145 of the second lower bridge arm 144 and the first ground terminal GNDM. This embodiment does not specifically limit this.

[0030] like Figure 2As shown, illustratively, the second end of the switch element 145 of the first lower bridge arm 142 is connected to the first ground terminal GNDM through the sampling resistor R50. In another example, the second end of the switch element 145 of the second lower bridge arm 144 can also be connected to the first ground terminal GNDM through the sampling resistor R50 to further protect the H-bridge drive circuit 121. That is, the sampling resistor R50 is connected in series in the motor circuit of the H-bridge drive circuit 121 to convert the current signal in the motor circuit into a voltage signal and sample it. Of course, in addition to setting the sampling resistor R50 between the switch element 145 of the first lower bridge arm 142 and the first ground terminal GNDM, the sampling resistor R50 can also be set between the first power supply V1 and the switch element 145 of the first upper bridge arm 141, as long as the sampling resistor R50 can collect the current signal. If the sampled voltage signal across sampling resistor R50 is too high, it can control the half-bridge driver chip to output a lower PWM control signal to switching element 145, thereby reducing the sampled voltage signal. Similarly, if the sampled voltage signal across sampling resistor R50 is too low, it can increase the PWM control signal output, thereby maintaining a stable sampled voltage signal and, consequently, a stable current in the motor circuit. Sampling resistor R50 effectively prevents oscillation or stalling of a bipolar stepper motor during stopping, ensuring a smooth and precise stop.

[0031] Building on the above embodiment, sampling resistor R50 also functions as a motor overcurrent detector. By monitoring the current signal flowing through the bipolar stepper motor, sampling resistor R50 ensures that the bipolar stepper motor operates within a safe range. When the motor current exceeds a set value, sampling resistor R50 feeds a sampled voltage signal back to the driver chip, thereby adjusting the motor's operating state and preventing overcurrent damage to the bipolar stepper motor or H-bridge driver circuit.

[0032] Continue to refer Figure 2 Optionally, the driving module 12 also includes a control unit 122 corresponding to each switching element 145; the control chip 13 is electrically connected to the control end of each switching element 145 of the driving module 12 through the control unit 122; wherein the control unit 122 includes a first resistor R1 and a first diode D1; the control signal output end of the control chip 13 is electrically connected to the first end of the first resistor R1 and the cathode of the first diode D1; the second end of the first resistor R1 and the anode of the first diode D1 are both electrically connected to the control end of the corresponding switching element 145; the control end of the switching element is electrically connected to the second end of the switching element through the second resistor; the output signal output by the driving module 12 to the bipolar stepping motor 11 tends to a standard pulse signal.

[0033] The driver module 12 also includes a control unit 122 corresponding one-to-one with each switching element 145. This control unit 122 is used to control the smoothness of the control signal transmitted from the control chip 13 to the control terminal of each switching element 145, thereby controlling the smoothness of the output signal of the bipolar stepper motor 11. The control unit 122 includes at least a first resistor R1 and a first diode D1. Specifically, the first resistor R1 and the first diode D1 are connected between the control signal output terminal of the control chip 13 and the control terminal of the corresponding switching element 145 to ensure that the output signal from the driver module 12 to the bipolar stepper motor 11 approaches a standard pulse signal.

[0034] The resistance parameters of the first resistor R1 can be controlled to reduce the overshoot burrs of the output signal, thereby further accelerating the switching speed of the switching element 145 and effectively suppressing the ringing burr phenomenon. In this embodiment, the resistance value of the first resistor R1 can be greater than the critical resistance value to ensure that the output signal output by the drive module 12 to the bipolar stepper motor 11 tends to be a standard pulse signal. For example, the critical resistance value does not exceed 100Ω. In this embodiment, the critical resistance value is set according to the specifications of the components in the bipolar stepper motor 11 and the drive module 12 to maintain the stability of the output signal of the drive module 12. There is no special limitation on the specific value of the critical resistance value. Specifically, as Figure 2 As shown, increasing the first resistor R1 reduces ringing but slows switching speed, while decreasing the resistor has the opposite effect. During design, it's important to consider both switching speed and ringing suppression. Multiple tests should be conducted to select the appropriate gate resistor and optimize the circuit layout.

[0035] The positive electrode of the first diode D1 is electrically connected to the control end of the corresponding switch element 145; the negative electrode of the first diode D1 is electrically connected to the second end of the corresponding first resistor R1; the control end of the switch element 145 is electrically connected to the second end of the switch element 145 through the second resistor R2. In order to further control the control signal of the control end of the switch element 145, the control unit 122 can also include a first diode D1, and the first diode D1 can control the switching speed of the switch element 145, so that the turn-off speed of the switch element 145 is faster, reducing the burrs of the output signal output by the drive module 12 to the bipolar stepper motor 11, thereby making the speed of the bipolar stepper motor 11 more stable and the wire feeding speed stable. Figure 2 As shown, by adjusting the gate drive resistance parameters of the switching element and adding the first diode D1, the first diode can make the switching element turn off faster, reduce the burrs in the output signal waveform, make the speed of the bipolar stepper motor 11 more stable, and stabilize the wire feeding speed. The existing output signal has overshoot burrs, increasing the resistance of the first resistor R1 can reduce the burr intensity. Figure 2As shown, the specific solution is to increase the first resistor R1 and influence the ringing glitch phenomenon by controlling the speed of the switching element 145. Increasing the first resistor can reduce the ringing but will reduce the switching speed of the switching element, while reducing the first resistor has the opposite effect.

[0036] like Figure 2 As shown, in a specific embodiment, according to the output waveform of the output signal, the resistance of the test resistor between the switching element 145 and the control chip 13 is adjusted so that the waveform of the output signal output by the drive module to the bipolar stepper motor approaches the standard pulse signal. At this time, the resistance of the resistor used for testing is determined. In actual production, another resistor R1 with the determined resistance in the warehouse is set between the switching element 145 and the control chip 13. In another specific embodiment, the specific adjustment test method is to increase the resistance of the test resistor, and affect the ringing glitch phenomenon by controlling the switching speed of the switching element 145. Increasing the test resistor can reduce the ringing but will reduce the switching speed of the switching element, while reducing the test resistor has the opposite effect. This embodiment can comprehensively consider the customer's requirements for switching speed and ringing suppression, select a suitable gate resistor through multiple tests, and optimize the circuit layout.

[0037] like Figure 3 As shown, Figure 3 This is a schematic diagram of a standard pulse signal provided by an embodiment of the present invention. Specifically, the output signal of the control drive module 12 in this embodiment approaches or infinitely approaches a square wave with no ringing or burring. This eliminates wire drag during feeding, achieving stable wire breaking and drawing. Figure 4 Schematic diagram of the output signal of the wire feeding control circuit in the prior art. Figure 4 As shown, because the output signal of the driving circuit to the DC motor in the prior art is prone to abnormal position A, there will be abnormal wire feeding such as dragging at the abnormal position A, causing the welding wire to be unable to break quickly, affecting the welding effect and the operator's operating efficiency.

[0038] In this embodiment, the control chip 13 may be a full-bridge driver chip that simultaneously controls the entire H-bridge driver circuit 121. Thus, each H-bridge driver circuit 121 requires a driver chip, which is not limited in this embodiment. Furthermore, the control chip 13 may optionally include: a first half-bridge driver chip U1 and a second half-bridge driver chip U2; the first half-bridge driver chip U1 is used to control the switching elements 145 (switching elements Q1 and Q2) of the first upper bridge arm 141 and the first lower bridge arm 142; and the second half-bridge driver chip U2 is used to control the switching elements 145 (switching elements Q1 and Q2) of the second upper bridge arm 143 and the second lower bridge arm 144. A single half-bridge driver chip can only be used to control the two switching elements 145 on one side of an H-bridge driver circuit 121. Therefore, using two half-bridge driver chips is necessary to control a single H-bridge driver circuit 121.

[0039] Continue to refer Figure 2 Optionally, the driving module 12 may further include: a pull-down unit 123; the pull-down unit 123 includes a third resistor R3; the first half-bridge driving chip U1 and the second half-bridge driving chip U2 may further include: an enable terminal; the enable terminal is electrically connected to the third ground terminal GND through the third resistor R3. A third resistor R3 may be set on the driving module 12 of the bipolar stepper motor 11. At the moment when the bipolar stepper motor 11 is powered on, there is a dead zone voltage in the first half-bridge driving chip U1, and the H-bridge driving circuit 121 may have the same-side switching elements turned on at the same time, causing the sampling resistor R50 or the switching element (Q1 / Q2) to burn out. By pulling down the enable terminal of the first half-bridge driving chip U1 through the third resistor R3, that is, inputting a low level to the enable terminal, it is effectively prevented that the same-side switching elements are turned on at the same time. When the laser welding system's single-chip microcomputer (master controller) controls the wire feed control circuit, the enable terminal can be connected to the microcontroller's common interface U3_IO, eliminating the need for the microcontroller to reuse the IO interface. This prevents dead-zone voltages and circuit burnout. Similarly, the second half-bridge driver chip U2 can also include an enable terminal electrically connected to the third ground terminal GND via a third resistor R3.

[0040] Continue to refer Figure 2 Optionally, both the first half-bridge driver chip U1 and the second half-bridge driver chip U2 may include an enable terminal. The enable terminal of the first half-bridge driver chip U1 is electrically connected to the first ground terminal GND via a first capacitor C1. The enable terminal of the second half-bridge driver chip U2 is electrically connected to the first ground terminal GND via a second capacitor C2. The first capacitor C1 and the second capacitor C2 help maintain a stable potential at the enable terminal, further improving the reliability of the half-bridge driver chip.

[0041] Continue to refer Figure 2Optionally, the first upper bridge arm 141 may include a first switching element Q1; the first lower bridge arm 142 may include a second switching element Q2; the first half-bridge driver chip U1 may include: an input control terminal, an enable terminal, a first control signal output terminal, and a second control signal output terminal; the first control signal output terminal is electrically connected to the control terminal of the first switching element Q1; the second control signal output terminal is electrically connected to the control terminal of the second switching element Q2; the first half-bridge driver chip U1 is further configured to control one of the first control signal output terminal and the second control signal output terminal to output an enable level based on an enable signal obtained from the enable terminal and a control signal obtained from the input control terminal, thereby regulating the rotation state of the bipolar stepper motor 11; the rotation state includes at least a direction and a speed. The input control terminal and the enable terminal serve as input controls and can jointly control the rotation state of the bipolar stepper motor 11, for example, controlling the direction, speed, and whether the bipolar stepper motor 11 is stopped. For example, if the high level of the enable terminal is valid, when the output terminal U3_IN3 of the single-chip microcomputer outputs a control signal to the first half-bridge driver chip U1, the first control signal output terminal and the second control signal output terminal alternately output the enable level (the high level is taken as an example in this embodiment), thereby controlling the switching elements of the first upper bridge arm 141 and the first lower bridge arm 142 to alternately turn on, and quickly and conveniently adjusting the rotation state of the bipolar stepper motor 11, ensuring normal wire breaking during laser welding, improving operating efficiency, and effectively solving the problem of welding material adhesion after laser welding is completed.

[0042] Similarly, the second upper bridge arm 143 may include a first switching element Q1; the second lower bridge arm 144 may include a second switching element Q2; the second half-bridge driver chip U2 includes: an input control terminal, an enable terminal, a first control signal output terminal, and a second control signal output terminal; the first control signal output terminal is electrically connected to the control terminal of the first switching element Q1; the second control signal output terminal is electrically connected to the control terminal of the second switching element Q2; the second half-bridge driver chip U2 is further configured to control the output of an enable level at one of the first control signal output terminal and the second control signal output terminal based on an enable signal received from the enable terminal and a control signal received from the input control terminal, thereby regulating the rotation state of the bipolar stepper motor 11; the rotation state includes at least direction and speed. The second half-bridge driver chip U2 controls the alternating conduction of the switching elements of the second upper bridge arm 143 and the second lower bridge arm 144, quickly and conveniently adjusting the rotation state of the bipolar stepper motor 11, ensuring normal wire breaking during laser welding, improving operational efficiency, and effectively resolving the problem of weld material adhesion after laser welding.

[0043] Continue to refer Figure 2Optionally, the driver module 12 may further include: a bootstrap unit 124; the bootstrap unit 124 includes: a third capacitor C3 and a second diode D2; the first half-bridge driver chip U1 may further include: a power input terminal, a high-side floating voltage input terminal, and a high-side floating voltage return terminal; the power input terminal is connected to the second power supply V2; the anode of the second diode D2 is electrically connected to the power input terminal; the cathode of the second diode D2 is electrically connected to the high-side floating voltage input terminal; the first terminal of the third capacitor C3 is electrically connected to the high-side floating voltage input terminal; the second terminal of the third capacitor C3 is electrically connected to the high-side floating voltage return terminal; the high-side floating voltage return terminal is electrically connected to the first node N1. In this embodiment, the second diode D2 is connected between the power input terminal and the high-side floating voltage input terminal, and the third capacitor C3 is connected between the high-side floating voltage input terminal and the high-side floating voltage return terminal. The above-mentioned third capacitor C3 and second diode D2 constitute a bootstrap circuit. Because the bipolar stepper motor 11 is positioned differently relative to the high-side floating voltage input and high-side floating voltage return terminals, and the switching element's turn-on condition requires a gate-source voltage difference (Vgs) greater than Vth (switching threshold voltage), a larger gate-to-ground voltage is required to turn on the first switching element Q1. The bootstrap circuit in the first half-bridge driver chip U1 provides a high voltage source to drive the first switching element Q1 in the H-bridge driver circuit 121. In the H-bridge driver circuit 121, the first switching element Q1 requires a voltage higher than the first power supply V1 to drive the first switching element Q1 (i.e., Vgs > Vth) to ensure that the first switching element Q1 is fully turned on. The bootstrap circuit utilizes the conduction of the second switching element Q2 to charge the first switching element Q1, raising the charged voltage to a level higher than the first power supply V1. This voltage is then supplied to the first switching element Q1 via the driver module 12, ensuring that the first switching element Q1 is fully turned on, thereby achieving effective H-bridge drive. Similarly, the second half-bridge driver chip U2 may further include: a power input, a high-side floating voltage input, and a high-side floating voltage return; the power input is connected to a second power source V2; the anode of a second diode D2 is electrically connected to the power input; the cathode of the second diode D2 is electrically connected to the high-side floating voltage input; a first terminal of a third capacitor C3 is electrically connected to the high-side floating voltage input; a second terminal of the third capacitor C3 is electrically connected to the high-side floating voltage return; and the high-side floating voltage return is electrically connected to the first node N1. Exemplarily, the second power source V2 may be 12V.

[0044] It should be noted that in this embodiment, the H-bridge drive circuit 121 is set in a one-to-one correspondence with the H-bridge drive circuit 121. This embodiment takes the H-bridge drive circuit 121 including two windings as an example, and thus this embodiment includes two H-bridge drive circuits 121. Correspondingly, two first half-bridge drive chips U1 and two second half-bridge drive chips U2 are required to drive the two H-bridge drive circuits 121 respectively. Figure 2The wire feeding control circuit shown in the figure can achieve a stable wire feeding speed of 160-200 mm / s. Furthermore, in the prior art, an encoder is required in the wire feeding control circuit as feedback for the wire feeding speed, which has high production costs and low production efficiency. Furthermore, the addition of the encoder increases the size of the DC motor assembly, which is not conducive to overall miniaturization and portable configuration. However, the bipolar stepper motor in this embodiment does not require an encoder. While meeting the high-precision requirements for wire feeding speed, the retraction speed can reach 160-200 mm / s. Furthermore, the motor is relatively small, making it easier for operators to meet the portability and high integration requirements of the wire feeding control assembly.

[0045] Figure 5 A schematic structural diagram of another wire feeding control circuit provided by an embodiment of the present invention, Figure 6 A schematic diagram of the structure of a power supply module provided in an embodiment of the present invention. Optionally, the wire feeding control circuit may further include: a power supply module 14; the power supply module 14 includes: a transient suppressor diode D3, a third diode D4, and a filter unit 15; the first end of the transient suppressor diode D3 is electrically connected to the first end of the external power supply CN1 and the anode of the third diode D4, respectively; the second end of the transient suppressor diode D3 is electrically connected to the second end of the external power supply CN1, the second input end of the filter unit 15, and the second ground terminal GNDE, respectively; and the cathode of the third diode D4 is electrically connected to the first input end of the filter unit 15. The external power supply CN1 includes a first end and a second end, which are used to input an external voltage to the terminals of the transient suppressor diode D3 of the power supply module 14 through the first and second ends. The transient suppressor diode D3 is used to prevent surges and improve external voltage stability. The external voltage then passes through the transient suppressor diode D3 to form the first power supply V1, which is supplied to the H-bridge drive circuit 121. The first power supply V1 then passes through the third diode D4 and the filter unit 15 to form the first auxiliary power supply V11. Afterwards, the first auxiliary power supply V11 can continue to be converted into 12V, 5V, and 3.3V through other voltage conversion modules to power the subsequent motor. During handheld laser welding, the switching between wire feeding and retraction generates a large reverse current, which affects the voltage of 24V11, causing the subsequent voltage fluctuation circuit to restart, and the single chip will re-enter the BOOT state, thereby affecting the normal wire feeding of the stepper motor. In order to solve this problem, a third diode D4 is set on the circuit connecting the two to prevent the subsequent power supply system from being affected by the reverse current of the stepper motor retraction. Optionally, Figure 6 As shown, the filtering unit 15 may include multiple filter components such as inductors and capacitors connected in parallel and / or in series, which is not particularly limited in this embodiment. It should be noted that the first ground terminal GNDM, the second ground terminal GND, and the third ground terminal GNDE are different ground terminals to maintain stability in different circuit environments.

[0046] Continue to refer Figure 6Optionally, the power supply module 14 may also include: a fuse F1; the fuse F1 is connected between the first end of the transient suppression diode D3 and the first end of the external power supply CN1. When the bipolar stepper motor 11 is operating normally, there may be abnormal conditions such as wire blockage in the wire feeding tube and wire winding in the wire feeding wheel, which may cause the bipolar stepper motor 11 to fail to operate normally, thereby causing the power supply circuit of the bipolar stepper motor 11 to have excessive current, causing the circuit and motor to heat up or even burn out. In order to solve this problem, a fuse F1 is designed in the power supply circuit. In the event of abnormal current, the power supply is cut off to protect the circuit and the bipolar stepper motor 11.

[0047] An embodiment of the present invention also provides a laser welding system. Figure 7 A schematic diagram of the structure of a laser welding system provided by an embodiment of the present invention is shown in FIG. Figure 7 As shown, the laser welding system provided by the embodiment of the present invention includes: a single chip microcomputer 21, a communication chip 22, a laser host 23 and a wire feeding control circuit 24 provided by any embodiment of the present invention;

[0048] The single chip microcomputer 21 is connected to the laser host 23 via the communication chip 22 and is used to write the rotation state of the bipolar stepper motor to the laser host 23; the rotation state includes at least the direction and speed;

[0049] The single chip microcomputer 21 is electrically connected to the wire feeding control circuit 24 and is used to send an enable signal and a control signal to the wire feeding control circuit 24 so that the wire feeding control circuit 24 transmits the welding wire through the bipolar stepping motor.

[0050] For example, the microcontroller can communicate with the laser host via a 232 chip, writing speed information to the laser host. The microcontroller then sends response instructions to the driver circuit, which is then executed by the stepper motor. The driver module consists of a dual H-bridge and eight MOSFETs. By combining microstepping and current setting with a control circuit, the bipolar stepper motor operates smoothly, with retraction and reversal speeds increased to 160 mm / s without lost steps, vibration, or abnormal noise. The system also operates smoothly even during low-speed wire feeding. Furthermore, the laser welding system can include a key circuit, which primarily includes manual wire feed and manual wire retraction functions, facilitating wire tube assembly and allowing for manual control of wire length. When using a handheld laser welding system, the operator controls the control button on the welding gun, which in turn controls wire feed and retraction via the key circuit. The improved wire feeder achieves a retraction speed of 160 mm / s, and stable wire feeding is achieved regardless of the driver circuit's low or high speed settings, improving welding quality. Automatic wire breakage and sticking prevention are achieved regardless of the operator's proficiency.

[0051] The laser welding system provided by the embodiment of the present invention includes the technical features of the wire feeding control circuit provided by any embodiment of the present invention, and has the beneficial effects of the corresponding technical features.

[0052] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A wire feeding control circuit, characterized in that: include: Bipolar stepper motor, driver module and control chip; The driving module includes an H-bridge driving circuit arranged in a one-to-one correspondence with the windings of the bipolar stepping motor; the H-bridge driving circuit includes a plurality of bridge arms; each of the bridge arms includes a corresponding switching element; a first upper bridge arm is electrically connected to a first lower bridge arm; a second upper bridge arm is electrically connected to a second lower bridge arm; a first node between the first upper bridge arm and the first lower bridge arm is connected to a first end of a corresponding winding; and a second node between the second upper bridge arm and the second lower bridge arm is connected to a second end of the corresponding winding; The first end of the switching element of the first upper bridge arm is connected to the first power supply; the second end of the switching element of the first upper bridge arm is connected to the first end of the switching element of the first lower bridge arm; the second end of the switching element of the first lower bridge arm is connected to the first ground end through the sampling resistor.

2. The wire feeding control circuit according to claim 1, characterized in that: The first end of the switching element of the second upper bridge arm is connected to the first power supply; the second end of the switching element of the second upper bridge arm is connected to the first end of the switching element of the second lower bridge arm; and the second end of the switching element of the second lower bridge arm is connected to the first ground.

3. The wire feeding control circuit according to claim 1, characterized in that: The control chip includes: a first half-bridge driver chip and a second half-bridge driver chip; the first half-bridge driver chip is used to control the switching elements of the first upper bridge arm and the first lower bridge arm; the second half-bridge driver chip is used to control the switching elements of the second upper bridge arm and the second lower bridge arm; The driving module also includes a control unit corresponding to each of the switching elements; the control chip is electrically connected to the control end of each switching element of the driving module through the control unit; wherein, the control unit includes a first resistor and a first diode; the control signal output end of the control chip is electrically connected to the first end of the first resistor and the cathode of the first diode; the second end of the first resistor and the anode of the first diode are both electrically connected to the control end of the corresponding switching element; the control end of the switching element is electrically connected to the second end of the switching element through a second resistor; the output signal output by the driving module to the bipolar stepper motor tends to a standard pulse signal.

4. The wire feeding control circuit according to claim 3, characterized in that: The driving module further includes: a pull-down unit; the pull-down unit includes a third resistor; The first half-bridge driver chip and the second half-bridge driver chip further include an enable terminal; the enable terminal is electrically connected to the third ground terminal through the third resistor.

5. The wire feeding control circuit according to claim 4, characterized in that: The first half-bridge driver chip and the second half-bridge driver chip each include: an enable terminal; The enable terminal of the first half-bridge driver chip is electrically connected to the third ground terminal through a first capacitor; the enable terminal of the second half-bridge driver chip is electrically connected to the third ground terminal through a second capacitor.

6. The wire feeding control circuit according to claim 3, characterized in that: The first upper bridge arm includes a first switching element; the first lower bridge arm includes a second switching element; The first half-bridge driver chip includes: an input control terminal, an enable terminal, a first control signal output terminal and a second control signal output terminal; The first control signal output terminal is electrically connected to the control terminal of the first switch element; the second control signal output terminal is electrically connected to the control terminal of the second switch element; The first half-bridge driver chip is also used to control the output enable level of one of the first control signal output terminal and the second control signal output terminal according to the enable signal obtained by the enable terminal and the control signal obtained by the input control terminal, so as to regulate the rotation state of the bipolar stepper motor; the rotation state includes at least direction and speed.

7. The wire feeding control circuit according to claim 3, characterized in that: The driving module further includes: a bootstrap unit; the bootstrap unit includes: a third capacitor and a second diode; The first half-bridge driver chip further includes: a power input terminal, a high-side floating voltage input terminal, and a high-side floating voltage return terminal; The power input terminal is connected to a second power supply; the anode of the second diode is electrically connected to the power input terminal; the cathode of the second diode is electrically connected to the high-side floating voltage input terminal; the first terminal of the third capacitor is electrically connected to the high-side floating voltage input terminal; the second terminal of the third capacitor is electrically connected to the high-side floating voltage return terminal; The high-side floating voltage return terminal is electrically connected to the first node.

8. The wire feeding control circuit according to claim 2, characterized in that: Also includes: Power supply module; The power supply module includes: a transient suppression diode, a third diode and a filtering unit; The first end of the transient suppression diode is electrically connected to the first end of the external power supply and the anode of the third diode respectively; the second end of the transient suppression diode is electrically connected to the second end of the external power supply, the second input end of the filter unit and the second ground end respectively; The cathode of the third diode is electrically connected to the first input terminal of the filter unit.

9. The wire feeding control circuit according to claim 8, characterized in that: The power supply module further includes: a fuse; the fuse is connected between the first end of the transient suppression diode and the first end of the external power supply.

10. A laser welding system, characterized in that: include: A single chip microcomputer, a communication chip, a laser host and a wire feeding control circuit according to any one of claims 1 to 9; The single chip microcomputer is connected to the laser host through the communication chip and is used to write the rotation state of the bipolar stepping motor to the laser host; The single chip microcomputer is electrically connected to the wire feeding control circuit and is used for sending an enable signal and a control signal to the wire feeding control circuit.

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