A method and system for thick plate narrow gap ring spot powder filling fiber laser welding

Abstract

The application provides a thick plate narrow gap annular light spot optical fiber laser powder filling welding method and system; the method comprises the following steps: groove shape design and pre-welding treatment; providing a laser welding system; providing an alternating magnetic field system; providing a weld contour detection system; using an annular light spot optical fiber laser beam to complete laser self-melting backing welding; turning on the weld contour detection system, the alternating magnetic field system and the laser welding system to perform powder filling welding; the application uses annular light spot optical fiber laser powder filling welding, improves the problems of serious evaporation and burning loss of powder elements, poor interlayer and sidewall fusion in traditional narrow gap laser powder filling welding; at the same time, the welding process is assisted by using the alternating magnetic field and the weld contour real-time detection method, the severe evaporation of the metal powder is avoided, the utilization rate of the metal powder material is improved, a full forming weld is obtained, and the weld collapse problem is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser welding, in particular to a thick plate narrow gap annular spot fiber laser powder filling welding method and system. BACKGROUND

[0002] With the rise of China's industrial comprehensive strength, the requirements for materials in the fields of weapons, ships, aviation and the like are further improved, and the equipment structure presents thick wall. Thick plate is widely used in welding structure due to its good corrosion resistance, high specific strength and the like. The narrow gap welding is characterized by using a smaller gap than traditional welding, and is a high-efficiency and energy-saving welding technology. Compared with the base material, the narrow gap joint has excellent mechanical properties, because the narrow gap welding has small heat input, fast cooling rate in the thick plate welding process, promotes grain refinement and enhances the strength and toughness of the weld, and the heat affected zone is narrow.

[0003] According to different processes, the narrow gap welding can use MIG, TIG, manual arc welding and laser welding and the like. Among them, the MIG and TIG welding has high requirements for the cathode treatment, and is prone to defects such as porosity, deformation and thermal damage. The manual arc welding is prone to defects such as undercut, incomplete fusion and large heat affected zone. The narrow gap pure laser welding has high assembly requirements. The joint performance cannot be improved by adjusting the weld composition, and the single-pass weldable thickness is limited. The narrow gap laser wire filling welding is prone to insufficient energy of the groove sidewall due to the too concentrated laser, causing incomplete fusion defects, and the Al, Mg and the like in the welding wire and the base material are prone to form hydrogen pores in the welding process. The narrow gap laser-arc composite welding is prone to cause excessive heat input due to the introduction of the arc, causing deformation. Compared with the traditional narrow gap laser wire filling welding, the narrow gap laser powder filling welding has many advantages, such as higher powder absorption rate of laser energy, easy adjustment of powder composition, effective reduction of thermal cracks and surface depression and the like. Secondly, the traditional laser beam is thin, and the powder utilization rate is not high; the powder is directly evaporated and burned under the irradiation of the high-energy density laser beam, which is serious. Therefore, we propose the annular spot laser powder filling welding to improve the powder utilization rate and reduce the burning loss.

[0004] With the development of high-power and high-quality fiber lasers, adjustable annular spot fiber lasers have been successfully developed in recent years. It is found that changing the intensity distribution of the focused laser spot on the workpiece, which is obviously different from the traditional single-peak Gaussian distribution, can realize high-speed and splash-free metal processing. SUMMARY

[0005] In order to solve the problems in the above cases, the present application aims to provide a thick plate narrow gap annular spot fiber laser powder filling welding method and system, so as to solve the problems of low powder utilization rate, serious evaporation and burning loss of powder elements and poor molten pool stability in the narrow gap laser powder filling welding.

[0006] The present application provides a kind of thick plate narrow gap annular spot powder filling welding method and system of fiber laser, comprising the following steps:

[0007] Step 1: polishing and cleaning the butt joint surface of the thick plate to be welded, removing surface oxide film, stains, etc., processing a U-shaped groove with a blunt edge at the welding position, and then clamping the thick plate with a clamp;

[0008] Step 2: providing a laser welding system, which includes an annular spot fiber laser, a transmission optical fiber, a laser welding head, a powder feeder, a powder feeding tube, an electrostatic powder feeding nozzle, and a conventional powder feeding nozzle;

[0009] Step 3: providing an alternating magnetic field system, which includes an electromagnetic coil, a power supply, and a cable;

[0010] Step 4: providing a weld contour detection system, which includes a CMOS industrial camera, a filter, and an industrial computer;

[0011] Step 5: turning on the laser welding system, turning on the annular spot fiber laser, and outputting a focused annular spot laser beam from the laser welding head to perform laser self-melting backing welding and complete the backing welding;

[0012] Step 6: turning on the alternating magnetic field system, powering on the electromagnetic coil to generate an alternating magnetic field that changes the direction of the magnetic field at a fixed frequency;

[0013] Step 7: turning on the annular spot fiber laser, outputting a focused annular spot laser beam from the laser welding head, turning on the electromagnetic field system, and turning on the powder feeding system to blow metal powder to the welding area through the electrostatic powder feeding nozzle and implement laser powder filling welding;

[0014] Step 8: turning on the weld contour detection system to scan the weld contour in real time, importing the data into the industrial computer, and controlling the powder feeding amount of the conventional powder feeding nozzle in real time according to the weld collapse amount by the industrial computer;

[0015] Step 9: after completing a weld, turning off the laser welding system, turning off the powder feeding system, turning off the alternating magnetic field system, and turning off the weld contour detection system, and returning the laser welding head to the starting point of welding;

[0016] Step 10: repeating steps 7-9 to perform multi-layer welding until the welding is completed.

[0017] Further, in step 1, the material of the thick plate can be carbon steel, stainless steel, aluminum alloy, and magnesium alloy.

[0018] Further, the material thickness is 20-50 mm.

[0019] Further, the width of the U-shaped groove bottom edge is 3-5 mm, and the blunt edge is 8-10 mm.

[0020] Further, in step 2, the electrostatic powder feeding nozzle and the conventional powder feeding nozzle are fixed to the laser welding head. The electrostatic powder feeding nozzle is located in front of the laser welding head, the angle between the end of the electrostatic powder feeding nozzle and the horizontal plane is β=30-60°, and the distance between the end of the electrostatic powder feeding nozzle and the surface of the workpiece to be welded is h1=1.5-5mm.

[0021] Further, in step 2, the conventional powder feeding nozzle is located behind the laser welding head, the angle between the end of the conventional powder feeding nozzle and the horizontal plane is γ=45-75°, and the distance between the end of the conventional powder feeding nozzle and the surface of the workpiece to be welded is h2=2-5mm.

[0022] Further, in step 6, the magnetic induction intensity of the electromagnetic coil is 30-90mT, and the magnetic field frequency is 1-20Hz.

[0023] The application also provides a thick plate narrow gap annular spot powder filling fiber laser welding system, which comprises a laser welding system, an alternating magnetic field system, a weld contour detection system, a welding fixture and an industrial computer. The laser welding system comprises an annular spot fiber laser, a transmission optical fiber, a laser welding head, a powder feeder, a powder feeding pipe, an electrostatic powder feeding nozzle and a conventional powder feeding nozzle. The weld contour detection system comprises a CMOS industrial camera, a filter and an industrial computer. The alternating magnetic field system comprises an electromagnetic coil, a power supply and a cable. The thick plate to be welded is fixed by the welding fixture. The industrial computer is responsible for analyzing the real-time weld contour surface image captured by the CMOS industrial camera, and controlling the powder feeding of the conventional powder feeding nozzle through signal feedback to realize real-time repair of the weld.

[0024] The application has the following advantages:

[0025] (1) The annular spot fiber laser powder filling welding is adopted in the application, in the welding process, the low energy density annular beam melts the metal powder in the front part, melts the side wall in the middle part, and stabilizes and insulates the molten pool in the rear part, while the high energy density center beam deeply melts and welds to ensure effective fusion between the multiple weld layers, which greatly improves the problems of serious evaporation and burning loss of powder elements, poor interlayer and side wall fusion in the traditional narrow gap laser powder filling welding, and the welding process is stable.

[0026] (2) The electrostatic powder feeding nozzle is adopted, so that the filled metal powder is charged, when the charged metal powder is sprayed out of the powder feeding pipe, it is affected by the Lorentz force under the action of the alternating magnetic field, and the metal powder is distributed in a ring shape, and finally the metal powder is filled in the action area of the low energy density annular beam, so that the metal powder is prevented from interacting with the high energy density center beam to cause severe evaporation, and the utilization rate of the metal powder material is improved.

[0027] (3) The weld collapse amount is detected in real time by the weld contour real-time detection system, and the powder feeding amount of the conventional powder feeding nozzle is adjusted in real time for compensation, so that a full forming weld is obtained, and the weld collapse problem is effectively solved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The overall structure schematic diagram of the thick plate narrow gap annular spot fiber laser powder filling welding.

[0029] Figure 2 The powder movement schematic diagram when the magnetic field direction is upward in the annular spot fiber laser powder filling welding.

[0030] Figure 3 The powder movement schematic diagram when the magnetic field direction is downward in the annular spot fiber laser powder filling welding.

[0031] Figure 4 The longitudinal schematic diagram of the annular spot fiber laser powder filling welding.

[0032] Figure 5 The transverse schematic diagram of the annular spot fiber laser powder filling welding.

[0033] In the figure, 1-laser head, 2-electromagnetic coil, 3-annular spot fiber laser beam, 4-base material, 5-conventional powder feeding nozzle, 6-static powder feeding nozzle, 7-weld, 8-alloy powder, 9-CMOS industrial camera, 10-industrial computer, 11-power supply, 12-groove, 13-ring beam, 14-center beam. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described in detail below in combination with the drawings and specific embodiments.

[0035] The present application provides a thick plate narrow gap annular spot fiber laser powder filling welding method, comprising the following steps:

[0036] Step 1: polishing and cleaning the butt joint surface of the thick plate to be welded, removing surface oxide film, stains, etc., wherein the thickness of the thick plate is 20-50 mm. Then a U-shaped groove is processed at the position to be welded, the bottom width is 3-5 mm, and the blunt edge is 8-10 mm, and then the thick plate is clamped with a clamp;

[0037] Step 2: providing a laser welding system, the laser powder filling welding system comprising an annular spot fiber laser, a transmission optical fiber, a laser welding head, a powder feeder, a powder feeding pipe, a static powder feeding nozzle, and a conventional powder feeding nozzle;

[0038] Step 3: provide an alternating magnetic field system, the alternating magnetic field system comprising an electromagnetic coil, a power supply, a cable. The electrostatic powder feeding nozzle and the conventional powder feeding nozzle are fixed to the laser welding head. The electrostatic powder feeding nozzle is located in front of the laser welding head, the electrostatic powder feeding nozzle end forms an angle β of 30-60° with the horizontal plane, and the distance h1 between the electrostatic powder feeding nozzle end and the surface of the workpiece to be welded is 1.5-5mm. The conventional powder feeding nozzle is located behind the laser welding head, the conventional powder feeding nozzle end forms an angle γ of 45-75° with the horizontal plane, and the distance h2 between the conventional powder feeding nozzle end and the surface of the workpiece to be welded is 2-5mm;

[0039] Step 4: provide a weld bead profile detection system, the weld bead profile detection system comprising a CMOS industrial camera, a filter, and an industrial computer. The CMOS industrial camera can detect the collapse amount;

[0040] Step 5: turn on the laser welding system, turn on the annular spot fiber laser, perform laser self-melting backing welding, and complete the backing welding;

[0041] Step 6: turn on the annular spot fiber laser and the alternating magnetic field system, turn on the powder feeder, the electrostatic powder feeding nozzle and the conventional powder feeding nozzle respectively blow the filler powder to the welding area, and turn on the weld bead profile detection system. The CMOS industrial camera scans the weld bead profile in real time, the data is imported into the industrial computer, and the industrial computer controls the powder feeding amount of the conventional powder feeding nozzle in real time according to the weld bead collapse amount. After welding one pass, turn off the laser welding system, the weld bead profile detection system, and the alternating magnetic field system, and the laser welding head returns to the welding starting point. Repeat the above steps to perform multi-pass welding until the welding is completed.

[0042] Although the present application is disclosed in detail with reference to the drawings, it is understood that these detailed descriptions are merely exemplary and are not intended to limit the application. The scope of protection of the present application is defined by the appended claims, and can include various modifications, improvements and equivalent arrangements made to the application without departing from the scope and spirit of the present application.

Claims

1. A method for thick plate narrow-gap annular spot fiber laser powder filling welding, characterized in that, Includes the following steps: Step 1: Perform pre-welding treatment. First, grind and clean the butt joint surfaces of the thick plates to be welded to remove the surface oxide film and dirt. Second, process a U-shaped bevel with a blunt edge at the welding point, and then clamp the thick plates with a fixture. Step 2: Provide a laser welding system, which includes a ring spot fiber laser, transmission fiber, laser welding head, powder feeder, powder feeding tube, electrostatic powder feeding nozzle, and conventional powder feeding nozzle. Step 3: Provide an alternating magnetic field system, including electromagnetic coils, power supply, and cables; Step 4: Provide a weld contour detection system, which includes a CMOS industrial camera, filters, and an industrial computer; Step 5: Turn on the laser welding system, turn on the ring spot fiber laser, and the laser welding head outputs a focused ring spot laser beam to perform laser self-fusion root pass welding to complete the root pass welding; Step 6: Turn on the alternating magnetic field system, turn on the power to energize the electromagnetic coil, and generate an alternating magnetic field that changes direction at a fixed frequency; Step 7: Turn on the ring-shaped fiber laser, the laser welding head outputs a focused ring-shaped laser beam, turn on the electromagnetic field system, turn on the powder feeding system, and the electrostatic powder feeding nozzle blows metal powder into the welding area to perform laser powder filling welding. The electrostatic powder feeding nozzle is located in front of the laser welding head, the angle β between the end of the electrostatic powder feeding nozzle and the horizontal plane is 30-60°, and the distance h1 between the end of the electrostatic powder feeding nozzle and the surface of the workpiece to be welded is 1.5-5mm. The conventional powder feeding nozzle is located behind the laser welding head, the angle γ between the end of the conventional powder feeding nozzle and the horizontal plane is 45-75°, and the distance h2 between the end of the conventional powder feeding nozzle and the surface of the workpiece to be welded is 2-5mm. Step 8: Turn on the weld contour detection system to scan the weld contour in real time, import the data into the industrial control computer, and the industrial control computer will control the powder feeding amount of the conventional powder feeding nozzle in real time according to the amount of weld collapse. Step 9: After completing one weld, turn off the laser welding system, powder feeding system, alternating magnetic field system, and weld contour detection system, and return the laser welding head to the welding start point; Step 10: Repeat steps 7-9 above to perform multi-layer welding until the welding is complete.

2. The method for thick plate narrow gap annular spot fiber laser powder filling welding according to claim 1, wherein in step 1, the material of the thick plate is carbon steel, stainless steel, aluminum alloy and magnesium alloy.

3. In the thick plate narrow gap annular spot fiber laser powder filling welding method according to claim 1, in step 1, the material thickness is 20-50mm.

4. In the thick plate narrow gap annular spot fiber laser powder filling welding method according to claim 1, in step 1, the bottom edge width of the U-shaped groove is 3-5mm and the blunt edge is 8-10mm.

5. In the thick plate narrow gap annular spot fiber laser powder filling welding method according to claim 2, in step 2, the electrostatic powder feeding nozzle and the conventional powder feeding nozzle are fixedly connected to the laser welding head.

6. In the thick plate narrow gap annular spot fiber laser powder filling welding method according to claim 2, in step 6, the magnetic induction intensity of the electromagnetic coil is 30-90mT and the magnetic field frequency is 1-20Hz.

7. A thick plate narrow gap annular spot fiber laser powder-filling welding system, characterized in that, The system includes a laser welding system, an alternating magnetic field system, a weld contour detection system, welding fixtures, and an industrial control computer. The laser welding system comprises a ring-spot fiber laser, a transmission fiber, a laser welding head, a powder feeder, a powder feeding tube, an electrostatic powder feeding nozzle, and a conventional powder feeding nozzle. The weld contour detection system includes a CMOS industrial camera, a filter, and an industrial control computer. The alternating magnetic field system includes an electromagnetic coil, a power supply, and cables. The thick plate to be welded is fixed using a welding fixture. The industrial control computer analyzes the real-time weld contour surface image captured by the CMOS industrial camera and controls the powder feeding of the conventional powder feeding nozzle through signal feedback to achieve real-time repair of the weld. The electrostatic powder feeding nozzle is located in front of the laser welding head, with an angle β = 30-60° between its end and the horizontal plane, and a distance h1 = 1.5-5mm between its end and the surface of the workpiece to be welded. The conventional powder feeding nozzle is located behind the laser welding head, with an angle γ = 45-75° between its end and the horizontal plane, and a distance h2 = 2-5mm between its end and the surface of the workpiece to be welded.

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