Dual-beam laser welding nozzle and weld seam automatic tracking system based on capacitance principle

Abstract

The embodiment of the present invention provides a dual-beam laser welding nozzle and weld automatic tracking system based on the capacitance principle, comprising: a ceramic nozzle, a first capacitance sensor and a second capacitance sensor installed on both sides of the ceramic nozzle; the first capacitance sensor and the second capacitance sensor are insulated from each other; the first capacitance sensor and the second capacitance sensor are used to synchronously collect the first capacitance value and the second capacitance value between the sensor and the nozzle respectively, the first capacitance value and the second capacitance value are calculated through the corresponding position, the position adjustment increment is obtained, and the position of the nozzle is adjusted according to the position increment. The problem of automatic focusing of the "T" type weld of laser welding is solved.

Description

Technical Field

[0001] The invention relates to the technical field of embedded controllers, and in particular to a double-beam laser welding nozzle and weld seam automatic tracking system based on the capacitance principle. Background Art

[0002] Common wall panels in aerospace structures are mainly composed of skin and internal reinforcement ribs. Such ribbed wall panels are generally connected between the skin and the ribs by riveting or resistance spot welding. These two traditional connection methods are not only labor-intensive and have low structural strength, but also damage the overall integrity of the skin.

[0003] Laser welding for manufacturing wall panel structural parts is an advanced manufacturing technology developed in recent years. The double-beam welding method has the advantages of high efficiency, small deformation, and good joint quality. The double-beam welding method uses two laser beams to weld synchronously from both sides of the vertical rib. Figure 1 As shown. The use of dual laser beams to simultaneously weld from both sides of the T-joint to form a fillet weld is conducive to the fusion of the ribs and the skin, and there is no damage to the back of the skin. It is generally believed that the use of dual-beam welding technology can make both sides of the T-joint heated evenly, which is conducive to controlling deformation. In addition, due to the simultaneous welding of two laser beams, the interaction of the molten pool can reduce the heat input to produce the effect of 1+1>2. At the same time, the interaction of the molten pool is conducive to the fusion of the joint surface between the ribs and the bottom plate, which is conducive to the escape of pores.

[0004] The double beam welding technology is used to weld the vertical reinforcement to the skin (bottom plate), such as Figure 2 As shown. After adopting the double-beam welding technology, compared with the traditional riveted wall panel, the double-beam welding structure has an overall weight reduction of 16% due to the elimination of the flange structure at the bottom edge. The connection between the ribs and the skin was originally a local spot welding connection. After the double-beam welding, the ribs and the skin are fully welded, and its strength is increased by more than 4 times. After the traditional riveting or resistance spot welding connection is completed, a pit with a depth of 0.3mm will be left on the aerodynamic surface of the skin (bottom plate), which seriously affects the overall structural integrity and stealth. The use of the T-shaped structure of double-beam welding can effectively prevent damage to the aerodynamic surface of the skin (bottom plate). The outer surface of the skin is smooth with a convexity or concave no more than 0.1mm. The electromagnetic radiation is reduced by more than 50% compared with the riveted structure, realizing the lightweight, high-strength and stealth manufacturing of titanium alloy wall panels.

[0005] However, during the laser dual-beam welding process, due to the influence of the incident angles of the two laser beams and the mutual disturbance of the molten pools on both sides, defects such as pores and lack of fusion are easily generated inside the weld, seriously affecting the welding quality.

[0006] When laser welding a "T" joint type structure, the laser dual beams weld from both sides of the T joint to form a fillet weld, which is conducive to the fusion between the vertical ribs and the base plate, and there is no damage to the back of the base plate. It is generally believed that the use of laser dual beam welding process can make both sides of the T joint heated evenly, which is conducive to controlling deformation. The interaction of the two laser beams in the molten pool can reduce the heat input at the same time, producing a 1+1>2 effect.

[0007] For existing dual-beam laser welding of wall panel structural parts, whether it is a dual robot platform processing method or a gantry welding platform, when welding workers are performing welding operations, they use a point-by-point teaching method to align the laser collimated light with the center of the weld to record the coordinate points, and use the method of connecting points into lines to generate the welding path. This method has poor accuracy and extremely low efficiency. It generally relies on visual work, and the workload is also extremely large, and the labor intensity of workers is very high. Moreover, the only way to improve the centering accuracy is to encrypt the teaching points, thereby further increasing the workload. As we all know, laser welding is famous for its efficient welding rate. The current welding teaching process accounts for more than 90% of the entire welding process, and the welding time is often only a few seconds to tens of seconds. Therefore, the use of welding teaching methods to center the weld has seriously affected the work efficiency, and there is an urgent need for an automatic centering method and device to realize the automatic centering of welding teaching.

[0008] Existing welding has the characteristics of fast welding speed and high accuracy requirements for the alignment of the welding head and the seam, which brings great difficulties to the seam detection. At present, a laser line structure plus an industrial camera is used to realize seam detection through triangulation. The outstanding problem is that the measuring device is about 100-150mm in front of the laser welding head. In the case of laser wire welding, since the wire feeding device and the seam detection device are both installed in front of the laser welding head, in order to prevent interference from the wire feeding device, the installation position of the detection device must be further advanced, resulting in a relatively large delay in responding to the detection signal and increasing the corresponding difficulty of the system. Summary of the invention

[0009] In order to solve the problem that the positions of the laser welding heads on both sides of the T-shaped weld cannot be accurately aligned in traditional welding because the wire feeding device and the seam detection device are both installed in front of the laser welding head. To this end, an embodiment of the present invention provides a dual-beam laser welding weld automatic tracking system based on the capacitance principle. The device is applied to laser welding "T"-shaped seam detection. The capacitance sensor is installed on the welding nozzle to synchronously obtain the position information of the welding nozzle, which solves the problem of automatic focusing of the laser welding "T"-shaped weld. At the same time, it avoids the system response problem caused by delay processing, which affects the welding quality. The specific technical solution is as follows:

[0010] To achieve the above-mentioned purpose, a first aspect of an embodiment of the present invention provides a dual-beam laser welding nozzle based on the capacitance principle, comprising a ceramic nozzle, a first capacitance sensor and a second capacitance sensor installed on both sides of the ceramic nozzle; the first capacitance sensor and the second capacitance sensor are insulated; the first capacitance sensor and the second capacitance sensor are used to synchronously collect the first capacitance value and the second capacitance value between the sensor and the part to be welded, respectively, and the MCU controller calculates the positions corresponding to the first capacitance value and the second capacitance value to obtain a position adjustment increment, and controls the motor to adjust the position of the nozzle according to the position increment.

[0011] Furthermore, it also includes a water tank for cooling the first capacitive sensor and the second capacitive sensor, and a metal seat is installed on the back of the nozzle; the first capacitive sensor and the second capacitive sensor are made of copper, and an insulating pad is installed behind the sensor.

[0012] A second aspect of an embodiment of the present invention provides a dual-beam laser welding weld seam automatic tracking system based on a capacitance principle, comprising:

[0013] An MCU controller, a parameter setting and monitoring platform connected to the MCU controller, a servo motor driver, and a capacitance detection device; a motor, a ball screw slide, and a welding nozzle connected to the MCU controller and the servo motor driver, wherein the capacitance detection device is installed on the welding nozzle via a capacitance sensor.

[0014] Furthermore, the capacitive sensor and the welding nozzle are fixed at a preset angle and calibrated.

[0015] Furthermore, the method further comprises installing a water jacket at the lower end of the capacitive sensor.

[0016] Furthermore, it also includes: a PWM signal modulation module and a differential conversion module; the signal collected by the capacitive sensor is modulated by the PWM signal modulation module and sent to the differential conversion module for differential conversion to obtain differential conversion data, which is input into the MCU controller. The MCU controller controls the servo motor driver according to the differential conversion data, thereby controlling the servo motor.

[0017] Furthermore, the servo control module includes magnetic isolation and optical coupling isolation connected to the MCU controller, a D / A conversion module connected to the magnetic isolation and the servo controller interface, the differential module is also connected to the optical coupling isolation and the servo controller interface respectively, and the level conversion module is connected to the optical coupling isolation and the servo controller interface respectively.

[0018] Furthermore, it also includes a human-computer interaction module, which is connected via an IO interface or a general industrial control data transmission line; the human-computer interaction module includes an indicator light, a touch screen, a start button and an emergency stop button.

[0019] Furthermore, the MCU controller adopts STM32F427.

[0020] The embodiment of the present invention provides a dual-beam laser welding nozzle based on the capacitance principle, including a ceramic nozzle, a first capacitance sensor and a second capacitance sensor installed on both sides of the ceramic nozzle; the first capacitance sensor and the second capacitance sensor are insulated; the first capacitance sensor and the second capacitance sensor are used to synchronously collect the first capacitance value and the second capacitance value between the sensor and the part to be welded, respectively, and the MCU controller calculates the position corresponding to the first capacitance value and the second capacitance value to obtain the position adjustment increment, and controls the motor to adjust the position of the nozzle according to the position increment. The problem of automatic focusing of the "T" type weld in laser welding is solved.

[0021] The second aspect of the present invention provides a dual-beam laser welding weld automatic tracking system based on the capacitance principle, comprising: an MCU controller, a parameter setting and monitoring platform connected to the MCU controller, a servo motor driver, and a capacitance detection device; a servo control module connected to the MCU controller and the servo motor driver, a servo motor, a ball screw slide, and a welding nozzle connected in sequence, and the capacitance detection device is installed on the welding nozzle through a capacitance sensor. The device is applied to laser welding "T" type seam detection, and the capacitance sensor is installed on the welding nozzle to synchronously obtain the position information of the welding nozzle, avoiding the system response problem caused by the delay processing, thereby causing problems affecting the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of double beam welding in the prior art;

[0023] Figure 2 It is a schematic diagram of welding the vertical reinforcement to the skin using double beam welding technology;

[0024] Figure 3 is a schematic structural diagram of a double-beam laser welding nozzle based on the capacitance principle provided by an embodiment of the present invention;

[0025] Figure 4 Schematic diagram of the control structure of a double-beam laser welding nozzle based on the capacitance principle provided by an embodiment of the present invention;

[0026] Figure 5 It is a structural schematic diagram of a dual-beam laser welding weld seam automatic tracking system based on the capacitance principle provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is described below in conjunction with the accompanying drawings, but is not intended to limit the scope of the present invention.

[0028] See also Figure 3 The double-beam laser welding nozzle based on the capacitance principle provided by the embodiment of the present invention comprises: a ceramic nozzle, a first capacitance sensor and a second capacitance sensor installed on both sides of the ceramic nozzle; the first capacitance sensor and the second capacitance sensor are insulated from each other. Figure 4 , is a control structure diagram of a dual-beam laser welding nozzle based on the capacitance principle provided by an embodiment of the present invention, including: a main control chip STM32F427, a capacitance digital conversion chip PCAP01 for collecting the capacitance values ​​of two capacitive displacement sensors and converting the processed capacitance values ​​into PWM signals and transmitting them to the main control chip, a communication module, wherein the main control chip of the communication module adopts ET1200, which is an EtherCAT bus slave communication module chip. The main control chip processes the received PWM signal into an EtherCAT message data packet and sends it to the EtherCAT bus. After the robot receives the message data packet through the EtherCAT bus, it reversely decodes it to obtain the position offset in two directions. According to the two position offsets, the welding trajectory is adjusted to realize weld tracking, thereby solving the problem of automatic focusing of the "T" type weld in laser welding.

[0029] The first capacitive sensor and the second capacitive sensor may also be referred to as capacitive sensor 1 and capacitive sensor 2 .

[0030] Furthermore, in a specific implementation of an embodiment of the present invention, the capacitive sensor is made of copper, has a layer of insulating material on the back, and is installed on a ceramic nozzle. A water tank is opened inside the ceramic nozzle, and cooling water circulates to ensure that the temperature of the capacitive sensor is constant during welding, and the two capacitive sensors are insulated from each other.

[0031] The present invention adopts a double-beam laser welding nozzle based on the capacitance principle, and two sets of capacitive displacement sensors are installed on the laser welding nozzle. In order to ensure the insulation between the two sets of capacitive displacement sensors, a ceramic laser welding nozzle is specially designed. The capacitive displacement sensor is made of copper, and an insulating pad is installed at the back. Since the accuracy of the capacitive displacement sensor is affected by temperature, and the reflected light, plasma, molten pool heat radiation and other factors in the welding process will cause the capacitive displacement sensor, a water tank is opened on the ceramic laser welding nozzle to cool the capacitive displacement sensor with cooling water to ensure measurement accuracy. Before welding, the angle of the laser welding nozzle should be adjusted to ensure that the two laser welding nozzles are facing the two sides of the "T"-shaped weld. The two analog quantities output by the sensor must also ensure that they correspond correctly.

[0032] See 4 and Figure 5 , Figure 5 The second aspect of the present invention provides a structural schematic diagram of a dual-beam laser welding weld automatic tracking system based on the capacitance principle, a dual-beam laser welding weld automatic tracking system based on the capacitance principle, comprising: an MCU controller, a parameter setting and monitoring platform connected to the MCU controller, a servo motor driver and a capacitance detection device; a servo control module connected to the MCU controller and the servo motor driver, a servo motor, a ball screw slide, and a welding nozzle connected in sequence, and the capacitance detection device is installed on the welding nozzle through a capacitance sensor.

[0033] In the present invention, the welding nozzle is installed in a cutting head. In the prior art, the cutting head includes a welding nozzle, a focusing lens, a focusing tracking system, and the like.

[0034] The capacitive sensor and the welding nozzle are fixed at a preset angle and calibrated. The purpose of calibration is to ensure the measurement accuracy and linear signal output. After successful calibration, no further calibration is required as long as the nozzle, amplifier, and control system are not replaced.

[0035] During operation, the two capacitive sensors of the dual-beam laser welding weld automatic tracking system synchronously collect the capacitance value between the capacitive sensor and the part to be welded (such as the uneven plate in the figure), and obtain the corresponding position analog value through capacitance digital conversion. After comparing with the preset position value, two incremental values ​​of position adjustment are obtained, which correspond to the gap between the nozzle and the "T"-shaped weld. The servo motor adjusts the position accordingly.

[0036] In an optional implementation manner of the embodiment of the present invention, in order to prevent the sensor from being damaged by heat radiation, spatter and reflected light during welding, a water jacket is provided at the lower end of the capacitive sensor.

[0037] In an optional embodiment of the present invention, the system also includes a PWM signal modulation module and a differential conversion module; the signal collected by the capacitive sensor is modulated by the PWM signal modulation module and sent to the differential conversion module for differential conversion to obtain differential conversion data, which is input into the MCU controller. The MCU controller controls the servo motor driver according to the differential conversion data, thereby controlling the servo motor.

[0038] In an optional embodiment of the present invention, the servo control module includes magnetic isolation and optical coupling isolation connected to the MCU controller, a D / A conversion module connected to the magnetic isolation and the servo controller interface, the differential module is also respectively connected to the optical coupling isolation and the servo controller interface, and a level conversion module is respectively connected to the optical coupling isolation and the servo controller interface.

[0039] In an optional embodiment of the present invention, a human-computer interaction module is also included, and the human-computer interaction module is connected via an IO interface or a general industrial control data transmission line; the human-computer interaction module includes an indicator light, a touch screen, a start button and an emergency stop button.

[0040] The user can operate and control the system in the human-computer interaction module. The MCU controller adopts STM32 series chips, which can be STM32F427 or STM32F407.

[0041] The embodiment of the present invention provides a dual-beam laser welding weld automatic tracking system based on the capacitance principle, including: an MCU controller, a parameter setting and monitoring platform connected to the MCU controller, a servo motor driver, and a capacitance detection device; a servo control module connected to the MCU controller and the servo motor driver, a servo motor, a ball screw slide, and a welding nozzle connected in sequence, and the capacitance detection device is installed on the welding nozzle through a capacitance sensor. The device is applied to laser welding "T"-shaped seam detection, and the capacitance sensor is installed on the welding nozzle to synchronously obtain the position information of the welding nozzle, avoiding the system response problem caused by the delay processing, thereby affecting the welding quality.

[0042] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A double-beam laser welding nozzle based on the capacitance principle, characterized in that: It includes a ceramic nozzle, a first capacitance sensor and a second capacitance sensor installed on both sides of the ceramic nozzle; the first capacitance sensor and the second capacitance sensor are insulated; the first capacitance sensor and the second capacitance sensor are used to synchronously collect the first capacitance value and the second capacitance value between the sensor and the part to be welded respectively, and the MCU controller calculates the positions corresponding to the first capacitance value and the second capacitance value to obtain the vertical position offset d1 and the horizontal position offset d2 of the laser welding nozzle relative to one side of the T-shaped weld to obtain the position information of the laser welding nozzle, and compares the position offsets d1 and d2 in these two directions with the preset position values ​​to obtain the position adjustment increments in these two directions, and controls the motor to adjust the position of the laser welding nozzle according to the position adjustment increment, adjusts the welding trajectory, ensures that the two laser welding nozzles are facing the two sides of the T-shaped weld, and realizes automatic focusing of the laser welding T-shaped weld.

2. The double-beam laser welding nozzle based on the capacitance principle according to claim 1 is characterized in that: It also includes a water tank for cooling the first capacitive sensor and the second capacitive sensor, and a metal seat is installed on the back of the ceramic nozzle; the first capacitive sensor and the second capacitive sensor are made of copper, and an insulating pad is installed behind the sensor.

3. A dual-beam laser welding weld seam automatic tracking system based on capacitance principle, characterized in that: include: The laser welding nozzle, MCU controller, parameter setting and monitoring platform, servo motor driver and capacitance detection device connected to the MCU controller as described in claim 1 or 2; a servo control module connected to the MCU controller and the servo motor driver, a servo motor and a ball screw slide connected in sequence, and the capacitance detection device is installed on the ceramic nozzle through a capacitance sensor.

4. The double-beam laser welding weld seam automatic tracking system based on the capacitance principle according to claim 3 is characterized in that: The capacitive sensor and the ceramic nozzle are fixed at a preset angle and calibrated.

5. The double-beam laser welding weld seam automatic tracking system based on the capacitance principle according to claim 3 is characterized in that: The method also includes installing a water jacket at the lower end of the capacitive sensor.

6. The double-beam laser welding weld seam automatic tracking system based on the capacitance principle according to claim 3 is characterized in that: Also includes: PWM signal modulation module and differential conversion module; the capacitive sensor is used to modulate the collected signal through the PWM signal modulation module and send it to the differential conversion module for differential conversion to obtain differential conversion data, which is input into the MCU controller, and then the MCU controller controls the servo motor driver according to the differential conversion data, thereby controlling the servo motor.

7. The double-beam laser welding weld seam automatic tracking system based on the capacitance principle according to claim 6 is characterized in that: The servo control module includes magnetic isolation and optical coupling isolation connected to the MCU controller, a D / A conversion module connected to the magnetic isolation and the servo motor driver interface, the differential conversion module is also connected to the optical coupling isolation and the servo motor driver interface respectively, and the level conversion module is connected to the optical coupling isolation and the servo motor driver interface respectively.

8. The double-beam laser welding weld seam automatic tracking system based on the capacitance principle according to claim 7 is characterized in that: It also includes a human-computer interaction module, which is connected via an IO interface or a universal industrial control data transmission line; the human-computer interaction module includes an indicator light, a touch screen, a start button and an emergency stop button.

9. The double-beam laser welding weld seam automatic tracking system based on the capacitance principle according to claim 3 is characterized in that: The MCU controller adopts STM32F427.

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