A "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding method and device

Abstract

The application belongs to the technical field of welding manufacturing, and discloses a "light-filament-powder" coaxial variable-frequency adjustable microstructure programming laser welding method and device. The device mainly comprises a laser welding system, a "light-filament-powder" coaxial feeding mechanism, a molten pool real-time temperature monitoring device and a self-adaptive variable-frequency regulator. The method realizes stable and synchronous feeding of filament and powder welding materials by using the "light-filament-powder" coaxial feeding mechanism, and based on a laser vision sensing device, the temperature distribution characteristics of the molten pool and the solidified weld are monitored in real time, the microstructure morphology is deduced, and the variable-frequency sub-control is adjusted to feed the filament, the powder and the laser energy waveform, so that the weld microstructure customization programming control welding is finally realized. The "light-filament-powder" coaxial variable-frequency adjustable microstructure programming laser welding method has high filling efficiency, strong adjustment ability and controllable weld microstructure, and solves the problems of frequent defects, uneven microstructure and performance in the welding process of complex structures.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of welding manufacturing, and discloses a "light-filament-powder" coaxial variable-frequency adjustable microstructure programming laser welding method and device. BACKGROUND

[0002] For the laser beam welding technology of an aviation complex main load-bearing component, the common difficulty at present is that the plate thickness size is large, and it is difficult to avoid the generation of coarse structure, non-uniform growth of structure and performance difference in local areas of the complex component during the welding process. The columnar crystal of part of light metal materials is coarse, and the interlayer fusion line grows longitudinally under multi-pass welding. This microstructure feature will seriously reduce the plasticity index of the large-size component, and further affect the service performance of the main load-bearing component under actual flight conditions. In order to solve the problems of frequent defects, non-uniform microstructure and performance in the welding process of the complex structure, the existing solutions are usually external energy field auxiliary methods such as ultrasonic auxiliary and magnetic field auxiliary, to refine the grains to regulate the microstructure and improve the performance. The regulation effect is limited compared with the in-situ fine grain regulation effect in the welding dynamic process, and the production efficiency is low. Therefore, how to develop a high-efficiency welding method for dynamic microstructure adjustment in the welding process has become an urgent need. SUMMARY

[0003] The purpose of the application is to provide a "light-filament-powder" coaxial variable-frequency adjustable microstructure programming laser welding method and device. Through the method of "welding seam temperature state real-time monitoring → microstructure morphology determination → self-adaptive variable-frequency regulator efficient algorithm determination → laser energy, filament-powder filling parameter variable-frequency regulation", the in-situ self-adaptive programming control of the welding seam microstructure is realized, and the problems of frequent defects, non-uniform microstructure and performance in the welding process of the complex structure are solved.

[0004] To achieve this purpose, the application adopts the following technical scheme:

[0005] A "light-filament-powder" coaxial variable-frequency adjustable microstructure programming laser welding method mainly includes the following steps:

[0006] Step 1: Turn on the shielding gas system to ensure that the workpiece to be welded and the filler metal in the inert gas protection cabin are continuously in a high-purity Ar gas atmosphere during the welding process;

[0007] Step 2: Turn on the laser welding system and the feeding mechanism in sequence, control the six-axis robot to move, teach the welding process, and preset the key welding process parameters: laser power P, pulse frequency H, welding speed V w , wire feeding speed V f , and powder feeding speed V p ;

[0008] Step 3: Activate the real-time temperature monitoring device for the molten pool and the adaptive frequency converter. During welding, the real-time temperature monitoring device on the side of the laser head records the temperature changes of the molten pool and transmits the temperature information to the computer. It records the high-temperature residence time ΔT above the interlayer weld phase transformation temperature and the molten pool cooling rate Rc, comparing this data with the metal solidification database to determine the microstructure and setting the current grain size G. s Grain size G of materials in the database a The difference ΔG = G s -G a Transmitted to the adaptive frequency converter;

[0009] Step four: The adaptive frequency converter can perform efficient algorithmic judgment based on real-time changes in tissue characteristic information. It has frequency conversion and peak value adjustment functions for laser energy, wire-powder filling parameters, and the converter has a parameter matching mechanism judgment formula. When the converter receives the ΔG signal, the powder feeding speed V... p1 =V p0 +H a ×(G s -G a ), wire feeding speed V f1 =V f0 -K b ×(G s -G a Laser power P = η p ×V p1 +η f ×V f1 To ensure dynamic matching during the multi-factor adjustment process, the content of fine grains in the molten pool can be dynamically controlled according to changes in microstructure.

[0010] Step 5: After welding is completed, the inert gas protective chamber is continuously ventilated for 5-10 seconds. After the welded workpiece cools to room temperature, the welding system, feeding mechanism, real-time temperature monitoring device, adaptive frequency converter and Ar gas protective gas are shut down in sequence.

[0011] Optionally, the adaptive frequency converter uses grain refinement as the main control strategy. During the welding process, based on the real-time transmitted temperature information and microstructure determination information, it adaptively controls the filling parameters of fine-grained powder, wire feeding parameters and laser energy to achieve dynamic programming of interlayer microstructure.

[0012] Optionally, when performing wire-powder synchronous laser welding on different metal materials, the powder feeding control coefficient K is adjusted. a , wire feeding control coefficient K b The unit heat of fusion coefficient η of welding powder p and the unit heat of fusion coefficient η of welding wire f Changes will occur, and process experiments will be conducted based on the unique welding characteristics of the material to fit and revise the coefficients.

[0013] A "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding device mainly comprises a laser welding system, a "light-fiber-powder" coaxial feeding mechanism, a molten pool real-time temperature monitoring device and a self-adaptive frequency conversion regulator.

[0014] The laser welding system generates a high-energy beam light source by a laser generator, and the laser light path is a hollow optical system, which successively passes through a collimating mirror, a roof prism and a hollow reflector, so that the light path is 90° bent and the hollow diameter is 50-100 mm, and a ring laser beam acts on the surface of a workpiece to be welded in an inert gas protection cabin.

[0015] The "light-fiber-powder" coaxial feeding mechanism mainly comprises a powder feeder, a powder storage box, a powder feeding port, a wire feeder and a laser head connected with a powder feeding pipe, and the center of the hollow reflector is a circular hole structure, so that the welding wire to be welded is fed from the center area to realize the coaxial melting effect; the filling powder composition is fine-grain strengthening particles, which are fed from the powder feeder to the powder feeding port of the laser head, and the powder is delivered to the center of the weld together with the laser beam and the welding wire.

[0016] The real-time temperature monitoring device is fixed to the front side of the welding direction of the laser head, performs infrared laser scanning on the weld area, monitors the temperature data in real time, and transmits the key information to a computer for analysis and extraction.

[0017] The self-adaptive frequency conversion regulator has three parts of laser energy, wire feeding parameters and powder feeding parameters, and can self-adaptively adjust the key parameters of energy size, pulse waveform and wire-powder filling ratio based on a judgment algorithm.

[0018] The beneficial effects of the present application are as follows:

[0019] The present application provides a "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding method and device, which realizes in-situ adaptive programming control of the weld tissue by real-time monitoring of the weld temperature state by a laser sensor, efficient algorithm decision of a computer database and a regulator, and self-adaptive regulation and control of laser energy and wire-powder filling parameters in the welding process, so as to solve the frequent defects, uneven tissue and performance problems in the welding process of complex structures. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic view of the internal planing structure of the integrated "light-fiber-powder" coaxial welding laser head, the temperature monitoring device and the self-adaptive frequency conversion regulator device;

[0021] Figure 2 is a structural schematic view of the "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding device provided by the present application;

[0022] In the figure: 1, Ar gas protection gas; 2, inert gas protection cabin; 3, laser generator; 4, laser head; 5, wire feeder; 6, powder feeder; 7, six-axis robot; 8, real-time temperature monitoring device; 9, computer; 10, adaptive frequency conversion regulator; 11, welding workpiece;

[0023] 41, optical fiber; 42, collimating mirror; 43, roof prism; 44, hollow mirror; 45, annular laser beam; 46, powder feeding port;

[0024] 51, filler wire;

[0025] 61, powder storage box. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0027] In the description of the present application, unless explicitly defined and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or integrated; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] In the present application, unless explicitly defined and limited, the first feature "on" or "below" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0029] In the description of the embodiments, the terms "upper", "lower", "right", "left", and the like, orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used to distinguish in the description, and have no special meaning.

[0030] The present application discloses a "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding device, such as Figure 1 The present application discloses a "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding device, such as

[0031] The present example is to realize the butt welding of 20mm thick plate TC4 titanium alloy by the above-mentioned "light-fiber-powder" coaxial frequency conversion adjustable tissue programming laser welding device. The implementation process is as follows:

[0032] Step one, before welding, the welding groove is cleaned, the to-be-welded plate is placed in the protection cabin, the protection gas system is started, and the to-be-welded workpiece and the filler welding material in the protection cabin are continuously kept in a high-purity inert atmosphere during the welding process;

[0033] Step two, the laser welding system and the feeding mechanism are opened in turn, the six-axis robot is controlled to move, the welding process is demonstrated, the key welding process parameters are preset, the laser power P is 3.5kW, the pulse frequency H is 30Hz, the welding speed V w is 0.8m / min, the wire feeding speed V f is 1.2m / min, and the powder feeding speed V p is 1.5rpm / s;

[0034] Step three, the molten pool real-time temperature detection device and the adaptive frequency conversion regulator are started, during the welding process, the temperature detection device performs infrared laser scanning on the weld area, real-time temperature data are monitored, and the temperature curve data are transmitted to the computer workstation, the αα and β phase phase transition temperature residence time and cooling speed are analyzed, the TC4 organization transformation temperature curve database is compared, it is judged that the current organization form is columnar crystal, and the information of ΔG=18μm(G s )-2μm(G a ) is transmitted to the adaptive frequency conversion regulator;

[0035] Step four, the adaptive frequency conversion regulator can perform efficient algorithm judgment based on the real-time changes of the α and β phase columnar crystal size, grain size organization characteristic information: V p1 =1.5rpm / s+K arpm / s, wire feeding speed V f1 = 1.2 m / min - K b rpm / s, laser power p = η p × 1.82 + η f × 1.04 = 3.74 kW, wherein for TC4 material, Ka = 0.02, K b = 0.01, η p = 1.2, η f = 1.5. The fine-grained particle filling amount is adjusted according to the tissue morphology to realize in-situ adaptive programming control of TC4 thick plate weld tissue;

[0036] Step five, after welding, the protection bin is continuously ventilated for 10 seconds, and after the TC4 thick plate workpiece is cooled to room temperature, the welding system, the feeding mechanism, the temperature monitoring device, the frequency regulator and the protection gas system are closed in turn.

[0037] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

[0038] The present application is not limited in any way to the example embodiments presented in the specification and drawings. Parts of the embodiments shown and described are expressly understood to be incorporated into the specification and expressly understood to fall within the scope of the present application. Moreover, many variations are possible within the scope of the present application as outlined in the claims. Furthermore, any reference signs in the claims should not be construed as limiting the scope of the present application.

Claims

1. A coaxial frequency-adjustable microstructure programming laser welding method using "light-filament-powder" technology, mainly comprising the following steps: Step 1: Turn on the protective gas system to ensure that the workpiece (11) to be welded and the filler welding material in the inert gas protective chamber (2) are continuously in a high-purity Ar atmosphere during the welding process; Step 2: Turn on the laser welding system and feeding mechanism in sequence, control the movement of the six-axis robot (7), teach the welding process, and preset the key welding process parameters: laser power P, pulse frequency H, welding speed Vw, wire feeding speed V t Powder delivery speed V p ; Step 3: Turn on the real-time temperature monitoring device (8) and adaptive frequency converter (10) of the molten pool. During the welding process, the real-time temperature monitoring device (8) on the side of the laser head (4) records the temperature change of the molten pool and transmits the temperature information to the computer (9). It records the high-temperature dwell time ΔT above the phase transformation temperature of the interlayer weld and the cooling rate Rc of the molten pool. It compares the data with the solidification database of metal materials to determine the microstructure and sets the current grain size G. s Grain size G of materials in the database a The difference ΔG = G s -G a Transmitted to the adaptive frequency converter (10); Step four, the adaptive frequency converter (10) can perform efficient algorithm judgment based on the real-time changes of tissue characteristic information. It has the functions of frequency conversion adjustment and peak value adjustment of laser energy and silk-powder filling parameters. The converter is equipped with a parameter matching mechanism judgment formula. When the converter receives the ΔG signal, the powder feeding speed V p1 =V p0 +K a ×(G s -G a ), wire feeding speed V f1 =V f0 -K b ×(G s -G a Laser power P = η p ×V p1 +η f ×V f1， To ensure dynamic matching during the multi-factor adjustment process, the content of fine grains in the molten pool is dynamically controlled according to changes in microstructure. Step 5: After welding is completed, the inert gas protective chamber (2) is continuously ventilated for 5-10 seconds. After the welded workpiece (11) cools down to room temperature, the welding system, feeding mechanism, real-time temperature monitoring device (8), adaptive frequency converter (10) and Ar gas protective gas (1) are shut down in sequence.

2. The "light-filament-powder" coaxial frequency-adjustable tissue programming laser welding method as described in claim 1, characterized in that: The adaptive frequency converter (10) uses grain refinement as the main control strategy. During the welding process, based on the real-time transmitted temperature information and microstructure determination information, it adaptively controls the filling parameters of fine-grained powder, wire feeding parameters and laser energy to realize dynamic programming of interlayer microstructure.

3. The "light-filament-powder" coaxial frequency-adjustable tissue programming laser welding method as described in claim 1, characterized in that: When performing wire-powder synchronous laser welding on different metallic materials, the powder feeding control coefficient K a , wire feeding control coefficient K b The unit heat of fusion coefficient η of welding powder p and the unit heat of fusion coefficient η of welding wire f Changes will occur, and process experiments will be conducted based on the unique welding characteristics of the material to fit and revise the coefficients.

4. The "light-filament-powder" coaxial frequency-adjustable tissue programming laser welding device for implementing the method of claim 1 mainly includes a laser welding system, a "light-filament-powder" coaxial feeding mechanism, a real-time temperature monitoring device for the molten pool (8), and an adaptive frequency converter (10); The laser welding system generates a high-energy beam light source from a laser generator (3), which is transmitted through an optical fiber (41). The laser beam path is a hollow optical system, which passes through a collimating lens (42), a roof beam splitter (43), and a hollow reflector (44) to achieve a 90° bend in the optical path and a hollow diameter of 50-100mm. The ring laser beam (45) acts on the surface of the workpiece to be welded inside the inert gas protective chamber (2). The "light-wire-powder" coaxial feeding mechanism mainly includes a powder feeder (6), a powder storage box (61), a powder feeding port (46), a wire feeder (5), and a laser head (4) connected to the powder feeding tube. The hollow reflector (44) has a central circular hole structure. The filler wire (51) to be welded is fed into the central area to achieve the coaxial wire melting effect. The filler powder is composed of fine-grained reinforced particles. It is connected to the powder feeding port (46) on the laser head (4) by the powder feeder (6) and coaxially transports the powder to the center of the weld with the annular laser beam (45) and the filler wire (51). The real-time temperature monitoring device (8) is fixed to the front side of the laser head in the welding direction, performs infrared laser scanning on the weld area, monitors the temperature data in real time, and transmits the key information to the computer (9) for analysis and extraction. The adaptive frequency converter (10) has three adjustment functions: laser energy, wire feeding parameters, and powder feeding parameters. It can adaptively adjust key parameters such as energy magnitude, pulse waveform, and wire feeding-powder feeding ratio based on the judgment algorithm.

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