Wire feeding control circuit and laser welding system

Abstract

The utility model discloses a wire feeding control circuit and a laser welding system. A driving module of the circuit comprises H-bridge driving circuits which are 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 utility model, the welding wire can be reliably broken.

Description

Technical Field

[0001] This utility model relates to the field of laser welding technology, and in particular to a wire feeding control circuit and a laser welding system. Background Technology

[0002] Laser welding is a highly efficient and precise welding method that uses a high-energy-density laser beam as a heat source. It is an important application of laser materials processing technology. In the 1970s, it was mainly used for welding thin-walled materials and low-speed welding. The welding process is heat conduction type; specifically, laser radiation heats the surface of the workpiece, and the surface heat diffuses inward through heat conduction. By controlling parameters such as the width, energy, peak power, and repetition frequency of the laser pulse, the workpiece is melted, forming a specific molten pool.

[0003] In the existing wire feeding welding process, the automatic wire breakage operation of laser welding is achieved by reversing the wire feeding wheel and pulling it back. Before the high energy density of the laser forms a molten pool and the molten pool rapidly crystallizes and fuses, the wire feeding wheel is pulled back in reverse to quickly remove the welding wire from the molten pool, thus avoiding the welding wire from being stuck in the molten pool or fusing with the workpiece surface, and achieving the purpose of automatic wire breakage.

[0004] However, in actual implementation, users may "intentionally" push the torch, which may cause the welding wire to fail to break properly, resulting in dragging of the welding material, adhesion of the welding material, and affecting the appearance of the weld. This also affects the welding effect and the operator's efficiency, causing inconvenience in actual use. Utility Model Content

[0005] This utility model provides a wire feeding control circuit and a laser welding system to achieve normal wire breakage and improve operating efficiency.

[0006] In a first aspect, this utility model embodiment provides a wire feeding control circuit, including: a bipolar stepper motor, a drive module, and a control chip;

[0007] The drive module includes an H-bridge drive circuit that corresponds one-to-one with the windings of the bipolar stepper motor; the H-bridge drive circuit includes multiple bridge arms; each bridge arm includes a corresponding switching element; a first upper bridge arm and a first lower bridge arm are electrically connected; a second upper bridge arm and a second lower bridge arm are electrically connected; a first node between the first upper bridge arm and the first lower bridge arm is connected to the first end of the corresponding winding; a second node between the second upper bridge arm and the second lower bridge arm is connected to the 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 terminal through a sampling resistor.

[0009] Secondly, this utility model embodiment also provides a laser welding system, including a microcontroller, a communication chip, a laser host, and a wire feeding control circuit provided in any embodiment of this utility model;

[0010] The microcontroller is connected to the laser host via the communication chip and is used to write the rotation state of the bipolar stepper motor to the laser host.

[0011] The microcontroller is electrically connected to the wire feeding control circuit and is used to send enable signals and control signals to the wire feeding control circuit.

[0012] In this invention, a bipolar stepper motor is used in the wire feeding control circuit to feed and retract the welding wire for 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 with each winding of the bipolar stepper motor corresponding to its winding. 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. Corresponding windings connect the first node and the second node. Each bridge arm includes a corresponding switching element. The first end of the first upper bridge arm is connected to a 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 a first ground terminal via a sampling resistor. This embodiment uses a bipolar stepper motor to achieve wire feeding and retraction, thereby stabilizing the wire feeding and retraction speeds, facilitating precise control of normal wire breakage, avoiding dragging at the welding point, and improving operational 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 and achieve smooth and precise stopping of the bipolar stepper motor, avoiding oscillation or stalling of the bipolar stepper motor. Attached Figure Description

[0013] Figure 1 A schematic diagram of a wire feeding control circuit provided in an embodiment of this utility model;

[0014] Figure 2 A schematic diagram of another wire feeding control circuit provided in an embodiment of this utility model;

[0015] Figure 3 A schematic diagram of a standard pulse signal provided for an embodiment of this utility model;

[0016] Figure 4This is a schematic diagram of the output signal of a wire feeding control circuit in the prior art;

[0017] Figure 5 A schematic diagram of another wire feeding control circuit provided in an embodiment of this utility model;

[0018] Figure 6 A schematic diagram of the structure of a power supply module provided in an embodiment of this utility model;

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

[0020] Explanation of reference numerals in the attached figures: 11-Bipolar stepper motor, 12-Drive module, 121-H-bridge drive circuit, 122-Control unit, 123-Pull-down unit, 124-Booting 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-Microcontroller, 22-Communication chip, 23-Laser main unit, 24-Wire feeding control circuit. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0022] To enable rapid retraction of the welding wire in contact with the molten pool and achieve wire breakage, a retraction speed greater than 100 mm / s is required. This speed is sufficient for basic wire breakage operations. Existing handheld laser welding systems use DC brushed motors as the drive motor for the wire feeder. The core of a DC brushed motor is to dynamically switch the current direction through brushes and a commutator, ensuring that the rotor windings are continuously subjected to a unidirectional electromagnetic force, thereby achieving stable operation. Its simple structure and low cost continue to make it widely used in many basic applications.

[0023] However, in the process of developing this application, the inventors discovered the following problems with using a DC brushed motor as the drive motor in a handheld laser welding system: the brushes have a limited lifespan and require periodic replacement, and high speeds can easily generate sparks; currently, when the speed of the DC brushed motor is increased, a polarization phenomenon occurs, with the motor speed easily becoming unstable, resulting in inconsistent wire feeding speeds and poor welding results. For example, when the wire feeding speed is adjusted to 5-30 mm / s and the retraction speed to 140 mm / s, if the wire feeding speed is stable, the retraction speed will be unstable, fluctuating between fast and slow; conversely, if the retraction speed is stable, the wire feeding speed will be unstable, fluctuating between fast and slow.

[0024] To address the aforementioned issues, this embodiment replaces the DC brushed motor with a bipolar stepper motor as the drive motor. A stepper motor is a special type of motor that converts electrical pulse signals into angular or linear displacement. Its key feature is the ability to precisely control the motor's rotation angle and speed by controlling the number, frequency, and direction of the input pulses. With gears differing by 1.8°, the motor rotates at the corresponding angle based on the number of pulses, enabling precise wire feeding and high-speed wire breakage. Each winding of a bipolar stepper motor can be energized in two directions, so one end of each winding can be either the N (north) or S (south) pole. This embodiment, using a bipolar stepper motor as the drive motor for the wire feeder, can increase the retraction speed to 160 mm / s without encountering the aforementioned problems of unstable wire feeding or retraction speeds.

[0025] Figure 1 This is a schematic diagram of the structure of a wire feeding control circuit provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of another wire feeding control circuit provided in an embodiment of the present invention. The present invention provides a wire feeding control circuit, such as... Figure 1 As shown, it includes: a bipolar stepper motor 11, a drive module 12, and a control chip 13;

[0026] The drive module 12 includes an H-bridge drive circuit 121 that corresponds one-to-one with the windings of the bipolar stepper motor 11. The H-bridge drive 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 a sampling resistor R50.

[0027] In this embodiment of the invention, a bipolar stepper motor is used in the wire feeding control circuit to feed and retract the welding wire for 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 with each winding of the bipolar stepper motor corresponding to the other winding. 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. Corresponding windings connect the first node and the second node. Each bridge arm includes a corresponding switching element. The first end of the first upper bridge arm is connected to a 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 a first ground terminal via a sampling resistor. This embodiment uses a bipolar stepper motor to achieve wire feeding and retraction, thereby stabilizing the wire feeding and retraction speeds, facilitating precise control of normal wire breakage, avoiding dragging at the welding point, and improving operational efficiency. In addition, the sampling resistor connected in series in the H-bridge drive circuit can 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 bipolar stepper motor from oscillating or stalling.

[0028] The above is the core idea of ​​this utility model. The technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0029] like Figure 2 As shown, Figure 2This embodiment provides an H-bridge drive circuit 121 for a wire feeding control circuit. The bipolar stepper motor 11 in this embodiment uses a dual H-bridge drive circuit as an example. Specifically, the H-bridge drive circuit 121 is configured to correspond one-to-one with the windings 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, and the multiple bridge arms include 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 sequentially electrically connected; 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 sequentially electrically connected. 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 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 142 is connected to the first ground terminal GNDM through a sampling resistor R50; similarly, the first end of the switching element 145 of the second upper bridge arm 143 is connected to the first power supply V1; the second end of the switching element 145 of the second upper bridge arm 143 is connected to the first end of the switching element 145 of the second lower bridge arm 144; the second end of the switching element 145 of the second lower bridge arm 144 is connected to the first ground terminal GNDM. For example, the first power supply V1 can be 24V. Optionally, the second end of the switching element 145 of the first lower bridge arm 142 is connected to the second end of the switching 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. It can be set between the second terminal of the switching element 145 of the first lower bridge arm 142 and the first ground terminal GNDM, or it can be set between the second terminal of the switching element 145 of the second lower bridge arm 144 and the first ground terminal GNDM. This embodiment does not impose any special limitations on this.

[0030] like Figure 2As shown, for example, the second end of the switching element 145 of the first lower bridge arm 142 is connected to the first ground terminal GNDM through a sampling resistor R50. In another example, the second end of the switching element 145 of the second lower bridge arm 144 can also be connected to the first ground terminal GNDM through a 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 switching 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 switching element 145 of the first upper bridge arm 141, as long as the sampling resistor R50 can collect the current signal. If the sampling voltage signal of the sampling resistor R50 is too high, the sampling voltage signal can control the PWM control signal output from the half-bridge driver chip to the switching element 145 to decrease, thereby reducing the sampling voltage signal. Similarly, if the sampling voltage signal of the sampling resistor R50 is too low, the sampling voltage signal will cause the PWM control signal output to increase, thereby maintaining the stability of the sampling voltage signal and thus maintaining the stability of the current in the motor circuit. The sampling resistor R50 can effectively prevent the bipolar stepper motor from oscillating or stalling when stopping, achieving a smooth and precise stop for the bipolar stepper motor.

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

[0032] Continue to refer to Figure 2 Optionally, the drive module 12 further includes a control unit 122 corresponding to each of the switching elements 145; the control chip 13 is electrically connected to the control terminals of each switching element 145 of the drive 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 terminal of the control chip 13 is electrically connected to the first terminal of the first resistor R1 and the negative terminal of the first diode D1; the second terminal of the first resistor R1 and the positive terminal of the first diode D1 are both electrically connected to the control terminal of the corresponding switching element 145; the control terminal of the switching element is electrically connected to the second terminal of the switching element through a second resistor; the output signal of the drive module 12 to the bipolar stepper motor 11 tends to be a standard pulse signal.

[0033] The drive module 12 also includes a control unit 122 corresponding to each of the switching elements 145. The control unit 122 is used to control the stability of the control signals transmitted from the control chip 13 to the control terminals of each switching element 145, thereby controlling the stability 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 of the drive module 12 to the bipolar stepper motor 11 tends to a standard pulse signal.

[0034] By controlling the resistance parameter of the first resistor R1, overshoot glitches in the output signal can be reduced, thereby further accelerating the switching speed of the switching element 145 and effectively suppressing ringing glitches. In this embodiment, the resistance value of the first resistor R1 can be greater than a critical resistance value to ensure that the output signal from the drive module 12 to the bipolar stepper motor 11 tends to 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 devices in the bipolar stepper motor 11 and the drive module 12, just enough to keep the output signal of the drive module 12 stable. There is no special limitation on the specific value of the critical resistance value. Specifically, as shown in the example... Figure 2 As shown, increasing the first resistor R1 reduces ringing but decreases switching speed, while decreasing the resistor has the opposite effect. During design, switching speed and ringing suppression must be considered holistically, and a suitable gate resistor should be selected through multiple tests, with optimized circuit layout.

[0035] The anode of the first diode D1 is electrically connected to the control terminal of the corresponding switching element 145; the cathode of the first diode D1 is electrically connected to the second terminal of the corresponding first resistor R1; the control terminal of the switching element 145 is electrically connected to the second terminal of the switching element 145 through the second resistor R2. To further control the control signal of the control terminal of the switching element 145, the control unit 122 may also include the first diode D1. The first diode D1 can control the switching speed of the switching element 145, making the switching speed of the switching element 145 faster, reducing glitches in the output signal from the drive module 12 to the bipolar stepper motor 11, thereby making the bipolar stepper motor 11 rotate more smoothly and the wire feeding speed more stable. Figure 2 As shown, by adjusting the gate drive resistor parameters of the switching element and adding the first diode D1, the first diode enables the switching element to turn off faster, reduces glitches in the output signal waveform, and makes the bipolar stepper motor 11 rotate more smoothly and the wire feeding speed more stable. The existing output signal has overshoot glitches; increasing the resistance value of the first resistor R1 reduces the glitches. For example... Figure 2As shown, the specific solution is to increase the first resistor R1. By controlling the speed of the switching element 145, the ringing glitches can be affected. Increasing the first resistor can reduce ringing but will reduce the switching speed of the switching element. Decreasing the first resistor will have the opposite effect.

[0036] like Figure 2 As shown, in one specific embodiment, the resistance value of the test resistor between the switching element 145 and the control chip 13 is adjusted according to the output waveform of the output signal, so that the waveform of the output signal from the drive module to the bipolar stepper motor tends to a standard pulse signal. At this point, the resistance value of the test resistor is determined. In actual production, another resistor R1 with the determined resistance value is used and positioned between the switching element 145 and the control chip 13. In another specific embodiment, the specific adjustment test method is to increase the resistance value of the test resistor. By controlling the switching speed of the switching element 145, the ringing glitches are affected. Increasing the test resistor reduces ringing but decreases the switching speed of the switching element, while decreasing the test resistor has the opposite effect. This embodiment can comprehensively consider the customer's requirements for switching speed and ringing suppression, selecting a suitable gate resistor and optimizing the circuit layout through multiple tests.

[0037] like Figure 3 As shown, Figure 3 This is a schematic diagram of the standard pulse signal provided in this embodiment of the present invention. That is, the output signal of the control drive module 12 in this embodiment tends towards or infinitely tends towards a square wave without ringing or glitches. At this time, the wire feeding will not experience dragging or other phenomena, and stable wire breakage and pulling can be achieved. Figure 4 This is a schematic diagram of the output signal of a wire feeding control circuit in the prior art. For example... Figure 4 As shown, because the output signal from the drive circuit to the DC motor in the existing technology is prone to abnormal position A, there will be abnormal wire feeding conditions such as dragging at abnormal position A, which will cause the welding wire to fail to break quickly, affecting the welding effect and the operator's operating efficiency.

[0038] In this embodiment, the control chip 13 can be a full-bridge driver chip that simultaneously controls the entire H-bridge drive circuit 121. Therefore, each H-bridge drive circuit 121 requires one driver chip, but this embodiment does not limit this. Alternatively, the control chip 13 may include: a first half-bridge driver chip U1 and a second half-bridge driver chip U2; the first half-bridge driver chip U1 controls the switching elements 145 (switching elements Q1 and Q2) of the first upper bridge arm 141 and the first lower bridge arm 142; the second half-bridge driver chip U2 controls the switching elements 145 (switching elements Q1 and Q2) of the second upper bridge arm 143 and the second lower bridge arm 144. Since one half-bridge driver chip can only control two switching elements 145 on one side of the H-bridge drive circuit 121, using half-bridge driver chips requires two chips to control one H-bridge drive circuit 121.

[0039] Continue to refer to Figure 2 Optionally, the drive module 12 may further include: a pull-down unit 123; the pull-down unit 123 includes a third resistor R3; the first half-bridge drive chip U1 and the second half-bridge drive 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 can be set on the drive module 12 of the bipolar stepper motor 11. At the instant the bipolar stepper motor 11 is powered on, the first half-bridge drive chip U1 has a dead-zone voltage, and the H-bridge drive circuit 121 may experience simultaneous conduction of switching elements on the same side, leading to the burning out of the sampling resistor R50 or the switching elements (Q1 / Q2). By setting the enable terminal of the first half-bridge drive chip U1 to be pulled down through the third resistor R3, that is, by setting the enable terminal to input a low level, the simultaneous conduction of switching elements on the same side is effectively prevented. When the microcontroller (main controller) in the laser welding system controls the wire feeding control circuit, the enable terminal can be connected to the microcontroller's ordinary interface U3_IO, eliminating the need for the microcontroller to use multiplexed IO interfaces and avoiding dead-zone voltage, thus preventing circuit burnout. Similarly, the second half-bridge driver chip U2 can also include: an enable terminal; the enable terminal is electrically connected to the third ground terminal GND through a third resistor R3.

[0040] Continue to refer to 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 through a first capacitor C1; the enable terminal of the second half-bridge driver chip U2 is electrically connected to the first ground terminal GND through a second capacitor C2. The first capacitor C1 and the second capacitor C2 help maintain the potential stability of the enable terminal, further improving the reliability of the half-bridge driver chip.

[0041] Continue to refer to 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 also used to control one of the first control signal output terminal and the second control signal output terminal to output an enable level according to the enable signal obtained by the enable terminal and the regulation signal obtained by the input control terminal, so as to regulate the rotation state of the bipolar stepper motor 11; the rotation state includes at least direction and speed. The input control terminal and the enable terminal serve as input control 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 enable terminal is high, when the output terminal U3_IN3 of the microcontroller 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 enable levels (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 conduct alternately, quickly and conveniently adjusting the rotation state of the bipolar stepper motor 11, ensuring normal wire breakage in laser welding, improving operating efficiency, and effectively solving the problem of welding material adhesion after laser welding.

[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 also used to control one of the first control signal output terminal and the second control signal output terminal to output an enable level 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 11; the rotation state includes at least direction and speed. The second half-bridge driver chip U2 controls the switching elements of the second upper bridge arm 143 and the second lower bridge arm 144 to conduct alternately, quickly and conveniently adjusting the rotation state of the bipolar stepper motor 11, ensuring normal wire breakage during laser welding, improving operating efficiency, and effectively solving the problem of weld material adhesion after laser welding.

[0043] Continue to refer to Figure 2Optionally, the driving 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 driving 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 a 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 third capacitor C3 and the second diode D2 constitute a bootstrap circuit. Because the bipolar stepper motor 11 is positioned differently relative to the high-side floating voltage input terminal and the high-side floating voltage return terminal, and the switching element's turn-on condition is that the gate-source voltage difference Vgs > Vth (switching threshold voltage), a relatively large gate-to-ground voltage is required for the first switching element Q1 to conduct. 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 needs a voltage higher than the first power supply V1 to drive it (i.e., Vgs > Vth) to ensure that the first switching element Q1 can be fully turned on. The bootstrap circuit charges by utilizing the conduction of the second switching element Q2 and raises the charging voltage to a level higher than the first power supply V1, then provides it to the first switching element Q1 through the driver module 12. This ensures that the first switching element Q1 can be fully turned on, thereby achieving effective H-bridge driving. Similarly, the second half-bridge driver chip U2 may also 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; and the high-side floating voltage return terminal is electrically connected to the first node N1. For example, the second power supply V2 can be 12V.

[0044] It should be noted that in this embodiment, the H-bridge drive circuits 121 are configured in a one-to-one correspondence. This embodiment illustrates an H-bridge drive circuit 121 with two windings as an example, thus including two H-bridge drive circuits 121. Correspondingly, two first half-bridge drive chips U1 and two second half-bridge drive chips U2 are needed to drive the two H-bridge drive circuits 121 respectively. Figure 2The wire feeding control circuit shown can achieve a stable wire feeding speed of 160-200 mm / s. However, existing wire feeding control circuits require an encoder for wire feeding speed feedback, which is costly, inefficient, and increases the size of the DC motor assembly, hindering miniaturization and portability. In contrast, the bipolar stepper motor in this embodiment does not require an encoder, meeting the high precision requirements for wire feeding speed while achieving a retraction speed of 160-200 mm / s. Its smaller size also facilitates portability and high integration for operators.

[0045] Figure 5 A schematic diagram of another wire feeding control circuit provided in an embodiment of this utility model. Figure 6 This is a schematic diagram 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 suppression diode D3, a third diode D4, and a filter unit 15; the first terminal of the transient suppression diode D3 is electrically connected to the first terminal of the external power supply CN1 and the positive terminal of the third diode D4, respectively; the second terminal of the transient suppression diode D3 is electrically connected to the second terminal of the external power supply CN1, the second input terminal of the filter unit 15, and the second ground terminal GNDE, respectively; the negative terminal of the third diode D4 is electrically connected to the first input terminal of the filter unit 15. The external power supply CN1 includes a first terminal and a second terminal, used to input external voltage to the two ends of the transient suppression diode D3 of the power supply module 14 through the first terminal and the second terminal. The transient suppression diode D3 is used to prevent surges and improve the stability of the external voltage. Then, the external voltage passes through the transient suppression diode D3 to form a first power supply V1 to supply the H-bridge drive circuit 121. Then, the first power supply V1 continues to pass through the third diode D4 and the filter unit 15 to form a first auxiliary power supply V11. Subsequently, the first auxiliary power supply V11 can be further converted to 12V, 5V, and 3.3V through other voltage conversion modules to power the subsequent motors. During handheld laser welding, the switching between wire feeding and retraction generates a large reverse current, which affects the voltage of 24V11, causing the voltage fluctuation circuit of the subsequent stage to restart. The microcontroller will then re-enter the BOOT state, thus affecting the normal wire feeding operation of the stepper motor. To solve this problem, a third diode D4 is placed on the circuit connecting the two, so that the subsequent power supply system is not affected by the reverse current of the stepper motor's retraction. Optional, such as Figure 6 As shown, the filter unit 15 may include multiple inductors, capacitors, and other filter devices connected in parallel and / or in series; this embodiment does not impose any special limitations on this. 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 to Figure 6Optionally, the power supply module 14 may also include a fuse F1; the fuse F1 is connected between the first terminal of the transient suppression diode D3 and the first terminal of the external power supply CN1. Under normal operating conditions, abnormalities such as wire blockage in the wire feed tube or wire winding on the wire feed wheel may cause the bipolar stepper motor 11 to malfunction, resulting in excessive current in the power supply circuit of the bipolar stepper motor 11, causing the circuit and motor to overheat or even burn out. To solve this problem, a fuse F1 is designed into the power supply circuit. In the event of abnormal current, the power supply is cut off, protecting the circuit and the bipolar stepper motor 11.

[0047] This utility model embodiment also provides a laser welding system. Figure 7 A schematic diagram of a laser welding system provided for an embodiment of this utility model is shown below. Figure 7 As shown, the laser welding system provided in this embodiment of the present invention includes: a microcontroller 21, a communication chip 22, a laser host 23, and a wire feeding control circuit 24 provided in any embodiment of the present invention;

[0048] The microcontroller 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 of rotation and the rotation speed.

[0049] The microcontroller 21 is electrically connected to the wire feeding control circuit 24 and is used to send enable signals and control signals to the wire feeding control circuit 24 so that the wire feeding control circuit 24 can feed the welding wire through the bipolar stepper motor.

[0050] For example, the microcontroller can communicate with the laser host via a RS-232 chip, writing speed information onto the laser host. The microcontroller sends response commands to the drive circuit, and the stepper motor executes them. The drive module consists of dual H-bridges and eight MOSFETs. By combining with the control circuit for micro-stepping and current settings, it achieves stable operation of the bipolar stepper motor, increasing the retraction and reversal speed to 160mm / s without step loss, vibration, or abnormal noise, and ensuring stable operation even at low wire feeding speeds. Furthermore, the laser welding system can also include a button circuit, which mainly includes manual wire feeding and manual wire retraction functions, facilitating wire tube assembly and allowing for manual control of the wire length. When using a handheld laser welding system, the operator controls the control buttons on the welding gun, thereby controlling the wire feeding and retraction via the button circuit. The improved wire feeder achieves a retraction speed of 160mm / s, and regardless of whether the drive circuit is in low-speed or high-speed mode, it can achieve stable wire delivery, thereby improving welding quality. It also automatically cuts wire and prevents sticking, regardless of the operator's skill level.

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

[0052] Note that the above description is merely a preferred embodiment 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 various obvious changes, readjustments, and substitutions can be made 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, drive module, and control chip; The drive module includes an H-bridge drive circuit that corresponds one-to-one with the windings of the bipolar stepper motor; the H-bridge drive circuit includes multiple bridge arms; each bridge arm includes a corresponding switching element; a first upper bridge arm and a first lower bridge arm are electrically connected; a second upper bridge arm and a second lower bridge arm are electrically connected; a first node between the first upper bridge arm and the first lower bridge arm is connected to the first end of the corresponding winding; a second node between the second upper bridge arm and the second lower bridge arm is connected to the 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 terminal through a 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; the second end of the switching element of the second lower bridge arm is connected to the first ground terminal.

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 drive module further includes a control unit corresponding to each of the switching elements; the control chip is electrically connected to the control terminals of each switching element of the drive module through the control unit; wherein, the control unit includes a first resistor and a first diode; the control signal output terminal of the control chip is electrically connected to the first terminal of the first resistor and the negative terminal of the first diode; the second terminal of the first resistor and the positive terminal of the first diode are both electrically connected to the control terminal of the corresponding switching element; the control terminal of the switching element is electrically connected to the second terminal of the switching element through a second resistor; the output signal of the drive 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 a third ground terminal through the third resistor.

5. The wire feeding control circuit according to claim 4, characterized in that, Both the first half-bridge driver chip and the second half-bridge driver chip 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 switching element; the second control signal output terminal is electrically connected to the control terminal of the second switching element. The first half-bridge driver chip is also used to control one of the first control signal output terminal and the second control signal output terminal to output an enable level according to the enable signal obtained by the enable terminal and the regulation 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 of rotation 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 also 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 source; 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; and 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 filter unit; The first terminal of the transient suppression diode is electrically connected to the first terminal of the external power supply and the positive terminal of the third diode, respectively; the second terminal of the transient suppression diode is electrically connected to the second terminal of the external power supply, the second input terminal of the filter unit, and the second ground terminal, respectively. The negative terminal 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 terminal of the transient suppression diode and the first terminal of the external power supply.

10. A laser welding system, characterized in that, include: The microcontroller, the communication chip, the laser host, and the wire feeding control circuit as described in any one of claims 1-9; The microcontroller is connected to the laser host via the communication chip and is used to write the rotation state of the bipolar stepper motor to the laser host. The microcontroller is electrically connected to the wire feeding control circuit and is used to send enable signals and control signals to the wire feeding control circuit.

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