Synchronous control method for double-machine linkage welding of ultrasonic generator

Abstract

The invention discloses an ultrasonic generator double-machine linkage welding synchronous control method, relates to the technical field of ultrasonic welding equipment, and solves the technical defects existing in an existing method for cooperatively controlling two ultrasonic generators during high-power ultrasonic welding. Signal transmission is carried out between the main ultrasonic generator and the slave ultrasonic generator through a synchronous expansion board and a communication cable; the master ultrasonic generator simultaneously generates a master drive signal and a phase-controllable slave drive signal during PWM (Pulse Width Modulation) processing, and the slave drive signal generated by the master ultrasonic generator is transmitted to the slave ultrasonic generator through the synchronous expansion board and the communication cable; after receiving the slave drive signal, the slave ultrasonic generator gives up the control right of the own drive signal, drives the slave transducer according to the slave drive signal, and only retains the protection monitoring function. Cooperative control of the two ultrasonic generators is achieved, a balun transformer is avoided, a high-power generator does not need to be specially designed, and the research and development, production and inventory cost is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultrasonic welding equipment, in particular to the improvement of the method for the coordinated control of two ultrasonic generators during high-power ultrasonic welding. BACKGROUND

[0002] In the application of high-power ultrasonic welding, especially in the case of welding difficult-to-weld materials or shortening the welding cycle, it is usually necessary to use two transducers for push-pull driving to provide more vibration energy. The ultrasonic generator driving two transducers requires that the two driving signals have the same frequency and a phase difference of 180°.

[0003] In the prior art, a single power supply is usually used in combination with a balun transformer (balanced transformer) to achieve double-transducer driving. This scheme uses two identical transformer secondary coils, but their like-named ends are opposite, thereby obtaining two driving signals with a phase difference of 180°. In order to prevent the problem of circulating current between the two transducers, it is necessary to connect the balun transformer in series in the circuit.

[0004] However, the prior art has the following defects: 1) A high-power generator needs to be specially designed, increasing the research and production costs; 2) The use of transformer reverse phase can only achieve a fixed 180° phase difference, and the phase cannot be adjusted, limiting the application range; 3) Balun transformers must be used to balance the current, increasing the complexity and cost of the system; 4) The two transducers are usually monitored as a whole, making it difficult to independently protect a single transducer. When the master-slave transducer characteristics deviate greatly, the lack of independent monitoring can easily cause the damage of a transducer with excessive amplitude; 5) Customized equipment is required, which complicates inventory management and increases maintenance costs. SUMMARY In summary, the present application aims to solve the above technical deficiencies in the prior art method for the coordinated control of two ultrasonic generators during high-power ultrasonic welding, and proposes a method for the synchronous control of ultrasonic generator double-machine linkage welding.

[0005]

[0006] ​The application discloses a synchronous control method for ultrasonic generator double-machine linkage welding, characterized in that two ultrasonic generators capable of independently driving transducers are respectively set as a master ultrasonic generator and a slave ultrasonic generator; the master ultrasonic generator and the slave ultrasonic generator are connected through a synchronous expansion board and a communication cable for signal transmission; the master ultrasonic generator simultaneously generates a master driving signal and a slave driving signal with controllable phase in PWM processing; the slave driving signal generated by the master ultrasonic generator is transmitted to the slave ultrasonic generator through the synchronous expansion board and the communication cable; the master ultrasonic generator drives a master transducer according to the master driving signal; after receiving the slave driving signal, the slave ultrasonic generator gives up the control of its own driving signal and drives a slave transducer according to the slave driving signal, and only retains a protection monitoring function.

[0007] The application further limits the technical scheme, and the features include: The communication cable is a network cable, four of the eight lines of the network cable form two pairs of differential signal lines for transmitting the slave driving signal generated by the master ultrasonic generator, two of the eight lines form a pair of differential lines for RS485 communication between the master ultrasonic generator and the slave ultrasonic generator, one line is used as an independent ground line, and one line is used as a start signal and an error synchronization line.

[0008] The synchronous expansion board comprises a differential signal conversion chip, a direction control circuit and a synchronous signal processing circuit. The differential signal conversion chip converts the PWM signal output by the master ultrasonic generator into a differential signal and transmits the differential signal to the slave ultrasonic generator through the communication cable, or converts the differential signal received by the slave ultrasonic generator into a PWM signal and provides the PWM signal to the MCU of the slave ultrasonic generator or directly drives the inverter circuit of the slave ultrasonic generator. The direction control circuit controls the differential signal conversion chip to switch between the receiving state and the transmitting state according to the direction switching signal output by the MCU of the master ultrasonic generator. The synchronous signal processing circuit comprises a resistor R16, a resistor R17, a capacitor C25 and a TVS tube D4, the resistor R16, the resistor R17 and the capacitor C25 are arranged between the synchronous signal line end of the communication cable interface and the MCU synchronous line end, the high level and the ground of the master ultrasonic generator and the slave ultrasonic generator to form an input protection circuit, and the TVS tube D4 is arranged between the synchronous signal line end of the communication cable interface and the ground to provide transient voltage protection.

[0009] In the start state of the slave ultrasonic generator, the slave ultrasonic generator monitors the synchronous signal, and when it is detected that the synchronous signal is pulled low, immediate shutdown protection is performed.

[0010] From the ultrasonic generator start state, periodically send real-time power and other measurement data to the master ultrasonic generator; when an anomaly is detected, pull down the synchronization signal for a period of time to notify the master ultrasonic generator to shut down.

[0011] The RS485 communication content includes: the master ultrasonic generator sends the working frequency information to the slave ultrasonic generator; and the slave ultrasonic generator replies to the master ultrasonic generator including but not limited to power, current, voltage, amplitude and impedance and other operating parameters.

[0012] The phase-controllable slave machine driving signal is 0°-360° phase control adjustment.

[0013] The beneficial effects of the present application are: 1) The present application uses the existing ultrasonic generator to increase the synchronization expansion board to realize the cooperative control of two ultrasonic generators, without the need for special design of high-power generator, which significantly reduces the research and development, production and inventory costs; 2) The driving signal of the two ultrasonic generators supports 0°-360° arbitrary phase adjustment, which is not only suitable for 180° push-pull driving, but also can be used for various applications requiring phase difference adjustment, such as ultrasonic processing, which expands the application range; 3) The two independent ultrasonic generators have independent loops, avoiding the use of balun transformers and reducing system cost and complexity; 4) The master-slave transducer can be independently and completely monitored and protected, improving system reliability and transducer service life; 5) The two ultrasonic generators are completely consistent in hardware, and are only distinguished by software settings, simplifying production, inventory management and maintenance; 6) Only one network cable is needed to realize all synchronization functions, including driving signal transmission, communication and error synchronization, and the wiring is simple; 7) Differential signal transmission is adopted, which has strong anti-interference ability and ensures signal transmission reliability. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The figure is a schematic diagram of the system framework structure of the present application; Figure 2 The figure is a schematic diagram of the synchronization signal circuit of the present application; Figure 3 The figure is a schematic diagram of the master-slave synchronization circuit of the single-channel PWM signal of the present application; Figure 4 The figure is a workflow diagram of the present application. DETAILED DESCRIPTION

[0015] The technical solutions of the present application will be further described in combination with the drawings and the preferred specific embodiments of the present application.

[0016] Referring toFigure 1 The application discloses a synchronous control method for ultrasonic generator double-machine linkage welding, as shown in the specification, the method sets two ultrasonic generators capable of independently driving transducers as a master ultrasonic generator and a slave ultrasonic generator; that is, the two ultrasonic generators are completely consistent in hardware, and are distinguished only by software setting, the master ultrasonic generator can independently drive a master transducer, the slave ultrasonic generator can independently drive a slave transducer, and the slave ultrasonic generator can also abandon self-control and cooperatively drive the slave transducer according to a phase-controllable slave driving signal provided by the master ultrasonic generator, so that the master transducer and the slave transducer can simultaneously control the respective transducers and perform linkage with a settable phase difference, and power superposition is realized.

[0017] To realize the cooperative control of the master ultrasonic generator on the slave ultrasonic generator, the application adds a synchronous expansion board in the master ultrasonic generator and the slave ultrasonic generator respectively, and signal transmission is performed through the synchronous expansion board and a communication cable; the master ultrasonic generator simultaneously generates a master driving signal and a phase-controllable slave driving signal in PWM processing, the slave driving signal generated by the master ultrasonic generator is transmitted to the slave ultrasonic generator through the synchronous expansion board and the communication cable; the master ultrasonic generator drives the master transducer according to the master driving signal; after receiving the slave driving signal, the slave ultrasonic generator abandons the control right of the self-driving signal and drives the slave transducer according to the slave driving signal, and only the protection monitoring function is reserved.

[0018] The slave driving signal serves as a synchronization signal for realizing the synchronous work of the slave ultrasonic generator and the master ultrasonic generator, the communication cable used in the transmission process can be a network cable, the synchronous expansion boards in the two ultrasonic generators are respectively provided with an RJ45 network port, and the network cable is inserted into the two RJ45 network ports at two ends to realize the signal transmission between the master ultrasonic generator and the slave ultrasonic generator.

[0019] Referring to Figure 2 Among the eight lines of the network cable, as shown in the specification, four lines form two pairs of differential signal lines and are used for transmitting the slave driving signal emitted by the master ultrasonic generator; for example, the fourth pin and the fifth pin of the RJ45 network port form a pair of differential signal lines, and the seventh pin and the eighth pin form another pair of differential signal lines; two lines form a pair of differential lines and are used for RS485 communication between the master ultrasonic generator and the slave ultrasonic generator; for example, the first pin and the second pin of the RJ45 network port form a pair of differential lines; one line serves as an independent ground line, for example, the third pin of the RJ45 network port; one line serves as a start signal and an error synchronization line, for example, the sixth pin of the RJ45 network port.

[0020] Referring to Figure 2 and Figure 3As shown in the figure, the synchronous expansion board comprises a differential signal conversion chip U2, a direction control circuit and a synchronous signal processing circuit. The differential signal conversion chip U2 converts the PWM signal output by the master ultrasonic generator into a differential signal and transmits the differential signal to the slave ultrasonic generator through a communication cable, or converts the differential signal received from the slave ultrasonic generator into a PWM signal and provides the PWM signal to the MCU of the slave ultrasonic generator or directly drives the inverter circuit of the slave ultrasonic generator; the PWM signal provided to the MCU of the slave ultrasonic generator is used as a phase-controllable slave driving signal, and the slave ultrasonic generator controls the power tube according to the PWM signal to drive the slave transducer to work. The direction control circuit controls the differential signal conversion chip to switch between the receiving and transmitting states according to the direction switching signal output by the MCU of the master ultrasonic generator; for example Figure 3 When the HRTIM_SYCN_DE end of the differential signal conversion chip U2 in the master ultrasonic generator is high, the differential signal conversion chip U2 is configured in an output mode, and when the HRTIM_SYCN_DE end is low, the differential signal conversion chip U2 is configured in an input mode.

[0021] The synchronous signal processing circuit comprises a resistor R16, a resistor R17, a capacitor C25 and a TVS tube D4, the resistor R16, the resistor R17 and the capacitor C25 are arranged in an input protection circuit between the synchronous signal line end of the communication cable interface and the MCU synchronous line end, the high level and the ground of the master ultrasonic generator\slave ultrasonic generator; the TVS tube D4 is arranged between the synchronous signal line end of the communication cable interface and the ground, and transient voltage protection is provided.

[0022] Referring to Figures 2 to 4 As shown in the figure, the working process of the master ultrasonic generator of the application comprises the following steps: When in standby mode, the synchronous signal output is low; When starting, the HRTIM_SYCN_DE signal output is high, so that the differential signal conversion chip U2 is in a signal output state; The PWM driving signal generated by the MCU of the master ultrasonic generator is converted into a differential signal by the differential signal conversion chip U2, and is transmitted to the slave ultrasonic generator through the network cable; At the same time, the open-drain output synchronous signal output is high, informing the slave ultrasonic generator to start; The master ultrasonic generator monitors the synchronous signal, and when it is detected that the synchronous signal is pulled low by the slave ultrasonic generator, immediate shutdown protection is performed.

[0023] The working process of the slave ultrasonic generator of the application comprises the following steps: After the synchronous function is started, the HRTIM_SYCN_DE signal output is low, so that the differential signal conversion chip U3 is in a signal input state; Receive the differential signal from the master ultrasonic wave generator, convert it into a PWM signal to directly control the power tube to drive the slave transducer; When the synchronization signal is detected to be high, the measurement monitoring function is started; Periodically send real-time power and other measurement data to the master ultrasonic wave generator; When an anomaly is detected, the synchronization signal is pulled low, such as pulling the synchronization signal low for 100ms, and the host computer is notified to shut down.

[0024] The RS485 communication content includes: the master ultrasonic wave generator sends the working frequency information to the slave ultrasonic wave generator; and the slave ultrasonic wave generator returns the operation parameters, including power, current, voltage, amplitude and impedance, to the master ultrasonic wave generator; the master ultrasonic wave generator integrates the data of the two machines, calculates the total power and energy consumption.

[0025] The phase-controllable slave drive signal of the application is a 0°-360° phase control adjustment, which is not only suitable for 180° push-pull driving, but also can be used for various applications requiring phase difference adjustment, such as ultrasonic processing.

[0026] Reference Figure 2 and Figure 3 As shown in the application, the slave ultrasonic wave generator receives the drive signal sent by the master ultrasonic wave generator, gives up the control right of the drive signal, and only retains the protection monitoring function. The HRTIM_SYCN_DE signal controls the signal input or output direction of the pins A and B of the differential signal conversion chip U2; The PWM drive signal is connected to the HRTIM_SYCN_1_TX pin through the resistor R12; The resistors R6 and R7 are pull-down resistors, and the impedance matching resistor R2 provides appropriate impedance to ensure signal stability. U9 is an AND gate chip, which ensures that the slave can only obtain the drive signal during the high level of the synchronization signal The differential signal is output to the network cable through OUT_SYCN_A and OUT_SYCN_B.

[0027] Embodiment 1: Master ultrasonic wave generator working process When the ultrasonic wave generator is set to the master mode: 1) Initialization stage: • Configure the synchronization signal GPIO as an open drain output mode; • Output low, indicating that the system is in standby state; • HRTIM_SYCN_DE outputs high, configuring the differential signal conversion chip U2 as an output mode.

[0028] 2) Start working stage: • The HRTIM timer of the host MCU (such as STM32G474) generates two PWM signals; • The first one is used to drive the host transducer; • The second one is sent to the slave ultrasonic generator through the synchronous expansion board after phase adjustment (such as 180°); • The synchronous signal configured in open-drain output mode outputs high level, informing the slave ultrasonic generator to start.

[0029] 3) Running monitoring phase: • Continuously monitor the state of the synchronous signal; • Receive the running parameters sent by the slave ultrasonic generator through RS485; • Integrate the data of the two machines and calculate the total power; • If the synchronous signal is detected to be pulled low, immediately stop the PWM output.

[0030] • Example 2: Working process of the slave ultrasonic generator When the ultrasonic generator is set to slave mode: 1) Initialization phase: • Configure the synchronous signal GPIO as input mode and enable interrupt; • HRTIM_SYCN_DE outputs low level, configure the differential chip as input mode; • Disable the PWM output function of the slave ultrasonic generator.

[0031] 2) Waiting for start phase: • Monitor the synchronous signal and wait for high level trigger; • Receive the frequency information sent by the master ultrasonic generator through RS485.

[0032] 3) Running working phase: • After detecting the high level of the synchronous signal, start the measurement protection function; • Receive the PWM signal sent by the master ultrasonic generator and directly drive the power tube; • Send measurement data to the master ultrasonic generator every 2ms; • Real-time monitor transducer parameters (voltage, current, amplitude, impedance, etc.).

[0033] 4) Abnormal protection phase: • When detecting parameter abnormalities, configure GPIO as output mode; • Output low level for 100ms to inform the host to stop; • Record abnormal information and wait for the master ultrasonic generator to query.

[0034] Example 3: Communication protocol RS485 communication adopts master-slave protocol: 1) Master regularly broadcasts: • Current working frequency (2 bytes); • Working status (1 byte); • Command word (1 byte).

[0035] 2) Slave responds: • Device status (1 byte); • Real-time power (2 bytes); • Current effective value (2 bytes); • Amplitude value (2 bytes); • Impedance value (2 bytes); • Error code (1 byte).

[0036] 3) Communication parameters: • Baud rate: 115200 bps; • Data format: 8-bit data bit, 1-bit stop bit, no check; • Communication period: 2ms in normal operation, 100ms in standby.

[0037] Example 4: Phase adjustment application The present application is not limited to 180° push-pull drive, and can realize any phase difference: 1) Ultrasonic processing application: • Set the phase difference to 90° to realize elliptical vibration; 2) Phase adjustment method: • In the master ultrasonic generator HRTIM configuration, the phase difference of two PWMs is set by modifying the comparator of the Master timer to synchronize to different sub-timers; • The phase resolution can reach 1°; • Supports dynamic adjustment without shutdown.

[0038] Example 5: System configuration System configuration is simple and flexible: 1) Hardware configuration: • The master ultrasonic generator and the slave ultrasonic generator use the same generator and synchronization board; • Connect through standard network cable (CAT5e or higher), and higher specification network cable should be used in high interference environment; • Use shielded network cable, and the length should not exceed 10 meters.

[0039] 2) Software configuration: • Select the working mode in the ultrasonic generator setting menu: o Master mode: sending synchronization signal; o Slave mode: receiving synchronization signal; o Off mode: working independently.

[0040] 3) Parameter setting: • Phase difference: 0°-359° adjustable; • Protection parameter: each protection threshold value can be independently set.

[0041] The application realizes the function of using standard equipment to complete high-power ultrasonic welding by the innovative double-machine synchronization method, which not only reduces the cost, but also improves the flexibility and reliability of the system. The method is especially suitable for metal welding and ultrasonic processing application fields which need high-power output.

[0042] The above only describes the preferred embodiments of the application and is not intended to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for synchronous control of ultrasonic generator double-machine linkage welding, characterized in that The method sets two independently drivable ultrasonic wave generators as a master ultrasonic wave generator and a slave ultrasonic wave generator, transmits signals between the master ultrasonic wave generator and the slave ultrasonic wave generator through a synchronous expansion board and a communication cable, generates a master driving signal and a phase-controllable slave driving signal in the master ultrasonic wave generator in PWM processing, transmits the slave driving signal to the slave ultrasonic wave generator through the synchronous expansion board and the communication cable, drives the master transducer according to the master driving signal in the master ultrasonic wave generator, and drives the slave transducer according to the slave driving signal in the slave ultrasonic wave generator after receiving the slave driving signal, only retaining a protection monitoring function.

2. The dual generator synchronization control method of claim 1, wherein: The communication cable is a network cable, four of the eight lines of the network cable form two pairs of differential signal lines for transmitting the slave driving signal from the master ultrasonic wave generator, two of the eight lines form a pair of differential lines for RS485 communication between the master ultrasonic wave generator and the slave ultrasonic wave generator, one line is an independent ground line, and one line is a start signal and error synchronization line.

3. The dual generator synchronization control method of claim 1, wherein: The synchronous expansion board comprises a differential signal conversion chip, a direction control circuit and a synchronous signal processing circuit. The differential signal conversion chip converts the PWM signal output by the MCU of the master ultrasonic wave generator into a differential signal and transmits the differential signal to the slave ultrasonic wave generator through the communication cable, or converts the differential signal received by the slave ultrasonic wave generator into a PWM signal and provides the PWM signal to the MCU of the slave ultrasonic wave generator. The direction control circuit controls the differential signal conversion chip to switch between receiving and transmitting states according to the direction switching signal output by the MCU of the master ultrasonic wave generator. The synchronous signal processing circuit comprises a resistor R16, a resistor R17, a capacitor C25 and a TVS tube D4, the resistor R16, the resistor R17 and the capacitor C25 are arranged between the synchronous signal line end of the communication cable interface and the MCU synchronous line end, the high level and the ground of the master ultrasonic wave generator\slave ultrasonic wave generator to form an input protection circuit, and the TVS tube D4 is arranged between the synchronous signal line end of the communication cable interface and the ground to provide transient voltage protection.

4. The dual generator synchronization control method of claim 1, wherein: In the slave ultrasonic wave generator start state, the slave ultrasonic wave generator monitors the synchronous signal, and when detecting that the synchronous signal is pulled low, executes immediate shutdown protection.

5. The dual generator synchronization control method of claim 4, wherein: In the slave ultrasonic wave generator start state, the slave ultrasonic wave generator periodically sends real-time power and other measurement data to the master ultrasonic wave generator, and when detecting an abnormality, pulls down the synchronous signal to notify the master ultrasonic wave generator to shut down.

6. The dual generator synchronization control method of claim 2, wherein: The RS485 communication content comprises that the master ultrasonic wave generator sends working frequency information to the slave ultrasonic wave generator, and the slave ultrasonic wave generator returns power, current, voltage, amplitude and impedance operating parameters to the master ultrasonic wave generator.

7. The dual generator synchronization control method of claim 1, wherein: The phase-controllable slave driving signal is a 0°-360° phase control adjustment.

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