A direct laser deposition system and method with optimized and controllable powder transfer

Abstract

The present invention discloses a direct laser deposition system and method for controlling optimized powder transfer, comprising a main air duct for powder delivery and cascaded air supply, a regulating system circuit for controlling an electric motor and the flow rate of each level of air ducts, a measurement feedback system circuit for measuring the particle distribution in the outlet space of the deposition head and providing reference and feedback for the control system, and a hollow truncated cone-shaped deposition head with a workbench at the bottom; mechanical dispersion fans are installed in the annular cavity of the deposition head to improve the uniformity of the metal powder in the annular cavity channel during transportation; a cascaded auxiliary air device realizes mainstream push flow and local turbulence to extend the length of the convergence section, regulate the position of the convergence surface, and further achieve uniform distribution of powder in the annular cavity; feedback regulation system working parameters are used to achieve rapid switching of optimized powder delivery under variable working conditions. The present invention is simple and clear, highly functional, and has a novel and reliable design. It helps to improve the quality of finished products in the fields of direct molding, surface coating, remanufacturing and repair, and reduce the complexity of post-processing processes.

Description

Technical Field

[0001] The invention belongs to the technical field of direct laser deposition, and relates to a direct laser deposition system and method with optimized and controllable powder transfer. Background Art

[0002] Direct Laser Deposition (DLD) is a rapid prototyping technology that uses the high-density energy of a laser beam to heat metal powder, causing it to melt and solidify, then deposit the metal layer by layer from bottom to top. This technology offers rapid heating and cooling during the workpiece manufacturing process, resulting in components with excellent overall performance and high manufacturing precision. This technology has been widely used in direct prototyping, surface coating, and remanufacturing and repair.

[0003] Powder delivery is crucial in the laser additive manufacturing process. Under the influence of carrier gas pressure, powder is ejected along the carrier gas path to the focal point, where it converges into a molten pool. However, at the outlet of the powder delivery tube, the carrier gas exerts a certain velocity and pressure on the powder, causing it to scatter. At the focal point, due to the velocity and mass of the powder, collisions alter its trajectory, causing the powder to regain its trajectory and move. Some powder will splash, resulting in poor convergence, hindering the formation of a molten pool and thus affecting processing quality. Therefore, good powder delivery is essential for improving powder utilization and achieving high-quality cladding layers.

[0004] In addition, factors such as the degree of powder heating and the length of the working section of the deposition head during direct laser deposition will also affect the quality of the finished product to varying degrees. Therefore, many scholars at home and abroad have improved the structure of the deposition head from various aspects and proposed a coaxial powder feeding nozzle. At present, the commonly used coaxial powder feeding nozzle is a multi-channel coaxial powder feeding nozzle, which has a simple structure, high processing efficiency, and strong practicality. However, the nozzle has poor gas-powder flow convergence and cross-sectional distribution uniformity, and its working section with the manufacturing surface is small, resulting in a weak ability of the deposition head to respond to the error of the manufacturing surface lifting and poor self-adjustment ability. Even a small error can easily lead to instability in the manufacturing process. Therefore, achieving optimized and controllable powder transfer is particularly important for improving the powder utilization efficiency of direct laser deposition and improving the molding quality. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a direct laser deposition system and method with optimized and controllable powder transfer, which can solve the problems of uneven powder delivery, difficulty in adjusting the position and length of the convergence surface during direct laser deposition, and poor molding quality.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0007] A direct laser deposition system with optimized and controllable powder transfer according to the present invention comprises:

[0008] The main air duct is used for powder conveying and cascade air supply, including a high-pressure gas tank, a ball valve, a buffer tank, a main air duct solenoid valve, a main air duct flow meter, and a six-way interface connected in sequence; the six-way interface is respectively connected to: a powder delivery pipeline, a primary push flow auxiliary air pipeline, a secondary disturbance auxiliary air pipeline, a tertiary rectification auxiliary air pipeline, and a quaternary control auxiliary air pipeline;

[0009] The regulating system circuit is used to control the electric motor and the flow of each level of air path. One end of the circuit is connected to the computer host, and the other end is connected to the main air path solenoid valve, powder feeding air path solenoid valve, push flow air path solenoid valve, disturbance air path solenoid valve, rectifier air path solenoid valve, control air path solenoid valve, periodic electric motor and solenoid valve through the aviation plug;

[0010] The measurement feedback system circuit is used to measure the particle distribution in the deposition head outlet space and provide reference and feedback for the control system. One end of the circuit is connected to the computer host and the other end is connected to the high-magnification camera. A light sheet is provided at the far end of the concentric axis of the high-magnification camera, and an auxiliary laser source is placed behind the light sheet.

[0011] An inner hollow conical deposition head has a workbench arranged underneath; the inner hollow conical deposition head includes an annular powder feeding chamber; a circular disc-shaped end cover is provided on the top of the annular powder feeding chamber, and a powder inlet is provided on the cover; an axial hole, a primary auxiliary air hole, a secondary auxiliary air hole group, a tertiary auxiliary air hole, a semicircular protrusion group and a quaternary auxiliary air hole are arranged on the outer wall block of the annular powder feeding chamber from top to bottom; a laser bracket is installed on the inner wall of the inner wall block of the annular powder feeding chamber, and a laser transmitter is placed on the laser bracket.

[0012] Specifically, the powder delivery pipeline is connected in sequence with: a powder delivery air path solenoid valve, a powder delivery air path flow meter, an air-powder mixing tank and one end of a powder delivery end connecting pipe; the other end of the powder delivery end connecting pipe is directly connected to the powder inlet; the air-powder mixing tank is also provided with a pipeline connected to the material tank, and an electromagnetic valve is provided on the pipeline.

[0013] Specifically, a mechanical dispersion fan is installed on the axial hole, and the other axial end of the mechanical dispersion fan is provided with a periodic electric motor fixed on the inner side of the inner wall of the deposition head.

[0014] Furthermore, the primary auxiliary air hole is connected to a primary air inlet pipe, and the other end of the primary air inlet pipe is connected to the primary air annular tube channel; the primary air annular tube channel is fixed to the disturbance wind annular tube channel through an auxiliary air tube bracket, and the primary air annular tube channel is also provided with a primary air inlet hole; the disturbance wind annular tube channel is directly connected to the disturbance wind inlet pipe group, and the other end of the disturbance wind inlet pipe group is connected to the secondary auxiliary air hole group; the secondary auxiliary air hole group includes a 45° downward blowing disturbance hole, a 45° right blowing disturbance hole, and a 45° left blowing disturbance hole. Blowing disturbance hole, upward 45° blowing disturbance hole; the upper part of the disturbance wind annular tube channel is also provided with a disturbance wind air inlet hole; the tertiary auxiliary air holes are connected to the rectified wind annular tube channel provided with the rectified wind air inlet hole through the rectified air inlet pipe, and the rectified wind annular tube channel is fixed to the outside of the primary air annular tube channel through the auxiliary air pipe bracket; the quaternary auxiliary air holes are connected to the regulating wind annular tube channel provided with the regulating wind air inlet hole through the regulating air inlet pipe, and the regulating wind annular tube channel is fixed to the outside of the rectified wind annular tube channel through the auxiliary air pipe bracket.

[0015] Furthermore, the primary push-flow auxiliary air duct is provided with: a push-flow air path solenoid valve, a push-flow air path flowmeter, and one end of a push-flow terminal connecting pipe in sequence, and the other end of the push-flow terminal connecting pipe is connected to the push-flow air inlet provided on the inner hollow conical deposition head; the secondary disturbance auxiliary air duct is provided with: a disturbance air path solenoid valve, a disturbance air path flowmeter, and one end of a disturbance terminal connecting pipe in sequence, and the other end of the disturbance terminal connecting pipe is connected to the disturbance air inlet provided on the inner hollow conical deposition head; the tertiary rectification auxiliary air duct is provided with: a rectification air path solenoid valve, a rectification air path flowmeter, and one end of a rectification terminal connecting pipe in sequence, and the other end of the rectification terminal connecting pipe is connected to the rectification air inlet provided on the inner hollow conical deposition head; the fourth control auxiliary air duct is provided with: a control air path solenoid valve, a control air path flowmeter, and one end of a control terminal connecting pipe in sequence, and the other end of the control terminal connecting pipe is connected to the control air inlet provided on the inner hollow conical deposition head.

[0016] Preferably, the diameters of the axial hole, primary auxiliary air hole, secondary auxiliary air hole group, tertiary auxiliary air hole, and quaternary auxiliary air hole are 1 / 4 to 1 / 3, 1 / 3 to 1 / 2, 1 / 4 to 1 / 3, 1 / 3 to 1 / 2, and 1 / 3 to 1 / 2 of the width of the annular powder feeding cavity, respectively; the diameter of the semicircular protrusion group is in a decreasing form, gradually decreasing from 1 / 3 of the width of the annular powder feeding cavity to 0.

[0017] Preferably, the axial hole, primary auxiliary air hole, secondary auxiliary air hole group, tertiary auxiliary air hole, and quaternary auxiliary air hole are evenly distributed on the outer wall of the annular powder feeding cavity with periods of 90°, 90°, 30°, 60°, and 90°, respectively.

[0018] A direct laser deposition method with optimized and controllable powder transfer according to the present invention is implemented using the above system and includes the following steps:

[0019] S1. Implementation of the powder transfer process for specific working conditions of direct laser deposition, specifically including:

[0020] S1.1. Open the ball valve to allow the inert gas in the high-pressure gas tank to flow into the buffer tank for buffering and preparation for use;

[0021] S1.2. Open the main air path solenoid valve to allow air to flow through the main air path flow meter and then into the six-way interface;

[0022] S1.3. Regulate the periodic electric motor to keep the mechanical dispersion blades in a vertical position so that the tangential direction of the blade surface is aligned with the particle delivery direction;

[0023] S1.4. Open the powder delivery air solenoid valve. Air can flow through the powder delivery pipeline and the powder delivery air flow meter into the air-powder mixing tank. At this time, the solenoid valve is opened simultaneously, allowing the powder material to fall from the material tank through the pipeline into the air-powder mixing tank.

[0024] S1.5. After uniform mixing, the powder particles and the powder-feeding air are fed into the annular powder-feeding cavity of the hollow, conical deposition head through the powder-feeding connecting tube and the powder inlet on the annular disk-shaped end cap. The cavity then exits and delivers the powder to the workbench, where it couples with the laser light emitted by the laser emitter, completing the layer formation process.

[0025] S1.6. Powder delivery under different working conditions can be achieved by matching the powder delivery air path solenoid valve and solenoid valve with the computer host;

[0026] S2. Measurement of the spatial distribution characteristics of powder concentration in the area below the deposition head:

[0027] S2.1. Turn on the auxiliary laser source and adjust the high-magnification camera position so that the light beam after passing through the light sheet is located on the center line of the high-magnification camera;

[0028] S2.2. Use a high-magnification camera to continuously capture the powder particles in the space below the hollow conical deposition head, perpendicular to the flow direction, and transmit the image data to a host computer.

[0029] S2.3. Calculate the particle concentration at a fixed position below the deposition head using Mie theory.

[0030] S2.4. Synchronously move the auxiliary laser source vertically, adjust the high-magnification camera and light sheet, measure and analyze the particle concentration at each location, and obtain the spatial distribution characteristics of the powder concentration;

[0031] S3. Control of the Direct Laser Deposition Powder Transfer Process

[0032] S3.1. Turn on the periodic electric motor, causing the mechanical dispersion blades to move in a pendulum-like motion around their end shafts, continuously breaking up the powder particles entering the annular powder feeding channel from the powder inlet. This disperses the powder within the annular channel, promoting a more uniform distribution of the powder flow around the circumference.

[0033] S3.2. Open the solenoid valve of the push flow path, so that the auxiliary air flow enters the annular cavity through the push flow path flow meter, the push flow terminal connecting pipe and the push flow air inlet hole to push the powder particles to continue to move downward rapidly;

[0034] S3.3. Open the solenoid valve of the disturbance air path, allowing the secondary disturbance airflow to pass through the disturbance air path flowmeter, the disturbance terminal connecting pipe and the disturbance air inlet hole into the annular powder delivery cavity to locally disturb and secondary disperse the powder particle flow transferred from S3.2, further adjusting the uniformity of the circumferential distribution of the powder flow;

[0035] S3.4. Open the rectifier air path solenoid valve, allowing the three rectifier air flows through the rectifier air path flowmeter, the rectifier end connecting pipe and the rectifier air inlet to enter the annular cavity. Combined with the semicircular protrusion group, the turbulent powder flow transmitted from S3.3 is continuously sinusoidally rectified to restore the turbulent flow to a laminar state.

[0036] S3.5. Open the regulating air path solenoid valve to allow the four regulated air flows to enter the annular cavity through the regulating air path flowmeter, the regulating end connecting pipe, and the regulating air inlet hole. This controls the velocity of the laminar powder flow transmitted from S3.4 and adjusts the position of the powder flow convergence plane and the neck length of the convergence surface.

[0037] S4. Optimization of direct laser deposition powder transfer process

[0038] S4.1. Based on the powder flow spatial distribution results measured by the high-magnification camera in step S2, the powder distribution uniformity and required convergence surface information are fed back to the host computer in combination with the workbench position;

[0039] S4.2. Adjust the power of the periodic electric motor and the opening of the disturbance air path solenoid valve to optimize the uniformity of the powder flow distribution within the circumference;

[0040] S4.3. Adjust the push flow solenoid valve, the rectifier solenoid valve, and the control solenoid valve to optimize the powder flow convergence plane position and convergence plane neck length.

[0041] S4.4. Use a high-magnification camera to measure the spatial distribution of the powder flow again and repeat steps S2 to S4 until the optimization adjustment is completed.

[0042] Specifically, in step S1, the particle size of the metal powder is in the range of 30 μm to 150 μm, and the transmission speed of the metal powder particles is 1 g / s to 10 g / s.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] 1. The present invention incorporates mechanical dispersion blades within the annular cavity of the deposition head. A regulating subsystem regulates the periodic electric motor of the mechanical dispersion blades, which are installed directly below the powder feed pipe. This controls the blades' initial postures under different operating conditions and their swing amplitudes during powder delivery, resulting in a more dispersed distribution of powder delivered from the powder feed pipe within the annular cavity.

[0045] 2. Add a cascade wind subsystem: The primary auxiliary air is responsible for accelerating the powder flow to the outlet; the secondary auxiliary air increases the local disturbance, making the powder flow locally turbulent, and promoting a more uniform distribution of the powder flow in the local space; the tertiary auxiliary air continuously sinusoidally rectifies the turbulent flow transmitted from the upper space, turning the powder flow back into laminar flow, laying the foundation for simpler control of the powder convergence surface; the quaternary auxiliary air is mainly responsible for the main regulation of the position of the powder flow convergence surface and the neck length; by adjusting the electromagnetic valves on each cascade air path by the adjustment subsystem, the flow rate and flow velocity of different cascade air can be changed. Overall, by changing the disturbance-pushing degree induced by the cascade wind, the uniformity of the metal powder conveying process is improved and the length and position of the working section are extended and adjusted;

[0046] 3. Add feedback and regulation subsystem: Provide more timely feedback and control of system operating parameters, and achieve rapid switching of powder optimization transfer under changing working conditions;

[0047] 4. The present invention can solve the problems of uneven distribution of metal powder and manufacturing instability in the process of conveying metal powder in traditional devices. Its system structure is simple and clear, the functionality is strong, and the setting is novel and reliable. It helps to improve the quality of finished products in the fields of direct forming, surface coating, remanufacturing and repair, and reduce the complexity of post-processing processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a structural schematic diagram of a direct laser deposition system with optimized and controllable powder transfer according to the present invention.

[0049] FIG2 is a three-dimensional schematic diagram of the structure of a hollow truncated cone-shaped deposition head according to an embodiment of the system of the present invention. Figure 2a This is the structural diagram of the hollow cone-shaped deposition head. Figure 2b This is a 180° cross-sectional view of a hollow truncated cone deposition head. Figure 2c This is a top view of the hollow truncated cone deposition head. Figure 2d It is a 40° cross-sectional view of a hollow truncated cone-shaped deposition head.

[0050] Among them: 1: main air duct; 2: regulation system circuit; 3: measurement feedback system circuit; 4: high-pressure gas tank; 5: ball valve; 6: buffer tank; 7: main air circuit solenoid valve; 8: main air circuit flow meter; 9: six-way interface; 10: powder delivery pipeline; 11: primary push flow auxiliary air pipeline; 12: secondary disturbance auxiliary air pipeline; 13: tertiary rectification auxiliary air pipeline; 14: quaternary control auxiliary air pipeline; 15: powder delivery air circuit solenoid valve; 16: powder delivery air circuit flow meter; 17: material tank; 18: pipeline; 19: air-powder mixing tank 20: Powder delivery end connection pipe; 21: Hollow inner truncated cone-shaped deposition head; 22: Push flow airway solenoid valve; 23: Push flow airway flowmeter; 24: Push flow end connection pipe; 25: Disturbance airway solenoid valve; 26: Disturbance airway flowmeter; 27: Disturbance end connection pipe; 28: Rectification airway solenoid valve; 29: Rectification airway flowmeter; 30: Rectification end connection pipe; 31: Control airway solenoid valve; 32: Control airway flowmeter; 33: Control end connection pipe; 34: Workbench; 35: High-magnification camera ;36: auxiliary laser source;37: sheet light board;38: computer host;39: electromagnetic valve;40: annular powder feeding cavity;41: circular disc end cover;42: powder inlet;43: shaft hole;44: primary auxiliary air hole;45: secondary auxiliary air hole group;46: tertiary auxiliary air hole;47: semicircular protrusion group;48: quaternary auxiliary air hole;49: laser bracket;50: laser emission head;51: mechanical dispersion fan;52: periodic electric motor;53: primary air inlet pipe;54: primary air annular pipe channel ; 55: Auxiliary air duct bracket; 56: Primary air inlet; 57: Downward 45° blowing disturbance hole; 58: Rightward 45° blowing disturbance hole; 59: Leftward 45° blowing disturbance hole; 60: Upward 45° blowing disturbance hole; 61: Disturbance air inlet duct group; 62: Disturbance wind annular circular tube channel; 63: Disturbance air inlet; 64: Rectification air inlet duct; 65: Rectification wind annular circular tube channel; 66: Rectification air inlet; 67: Control air inlet duct; 68: Control wind annular circular tube channel; 69: Control air inlet. DETAILED DESCRIPTION

[0051] The present invention provides a direct laser deposition system and method for controlling optimized powder transfer, the system comprising a main air duct, a regulating system circuit, a measuring feedback system circuit, a hollow conical deposition head, a powder delivery duct, a cascaded auxiliary air duct, a mechanical dispersion fan blade, a semicircular protrusion group, a high-magnification camera, a computer host, a number of solenoid valves and a gas flow meter. The following functions can be achieved through this system: by adding a mechanical dispersion device, the uniformity of the metal powder in the annular channel conveying process is improved; by adding cascaded auxiliary air, the mainstream push flow and local turbulence are achieved to extend the length of the convergence section, regulate the position of the convergence surface and further achieve uniform distribution of the powder in the annular cavity; the feedback adjustment system working parameters are used to achieve rapid switching of optimized powder transfer under variable working conditions. The present invention is simple and clear, highly functional, and has a novel and reliable configuration, which helps to improve the quality of finished products in the fields of direct molding, surface coating, remanufacturing and repair, and reduce the complexity of post-processing processes.

[0052] The present invention will be described in further detail below with reference to the accompanying drawings.

[0053] Reference Figure 1 The present invention provides a direct laser deposition system with optimized and controllable powder transfer, comprising a main air duct 1, a regulating system circuit 2, a measurement feedback system circuit 3, and a hollow truncated cone-shaped deposition head 21.

[0054] The main air duct is used for powder transportation and cascaded air supply; the adjustment system circuit is used to control the electric motor and the flow rate of each level of air duct; the measurement feedback system circuit is used to measure the particle distribution in the outlet space of the deposition head and provide reference and feedback for the control system; the hollow conical deposition head is the main structure for achieving optimized and controllable powder delivery.

[0055] The main air duct 1 is connected in sequence to a high-pressure gas tank 4, a ball valve 5, a buffer tank 6, a main air path solenoid valve 7, a main air path flow meter 8, and a six-way interface 9; the six-way interface 9 is respectively connected to a powder delivery pipeline 10 for conveying powder particles, a primary push flow auxiliary air pipeline 11 for accelerating the flow of powder in the annular cavity channel, a secondary disturbance auxiliary air pipeline 12 for achieving a local disturbance of the annular cavity flow field, a tertiary rectification auxiliary air pipeline 13 for regularizing the powder flow to return to a laminar state, and a fourth regulation auxiliary air pipeline 14 for accelerating the flow of powder in the annular cavity channel again.

[0056] The powder delivery pipeline 10 is connected in sequence to the powder delivery air path solenoid valve 15, the powder delivery air path flowmeter 16, the air-powder mixing tank 19, and the powder delivery end connecting pipe 20; the air-powder mixing tank 19 is also provided with a pipeline 18 connected to the material tank 17, and the pipeline is provided with an electromagnetic valve 39; the other end of the powder delivery end connecting pipe 20 is connected to the hollow frustum-shaped deposition head 21.

[0057] 2 , the inner hollow conical deposition head 21 is an axisymmetric structure, including an annular powder feeding chamber 40, the top of which is provided with an annular disc-shaped end cover 41, the cover 41 being provided with a powder inlet 42, and the powder feeding end connecting pipe 20 is directly connected to the powder inlet 42; the outer wall block of the annular powder feeding chamber 40 is provided with an axial hole 43, a primary auxiliary air hole 44, a secondary auxiliary air hole group 45, a tertiary auxiliary air hole 46, a semicircular protrusion group 47 and a quaternary auxiliary air hole 48 in sequence from top to bottom; a workbench 34 is also placed below the annular powder feeding chamber 40, and a laser bracket 49 is installed on the inner wall of the inner wall block thereof, and a laser emission head 50 is placed on the laser bracket 49.

[0058] A mechanical dispersion fan 51 is installed on the shaft hole 43. The mechanical dispersion fan 51 is located just below the powder inlet 42 and is used to break up and disperse the powder mass flow transmitted from the powder inlet 42 into the annular channel of the deposition head. The other shaft end of the mechanical dispersion fan 51 is provided with a periodic electric motor 52 fixed on the inner side of the inner wall of the deposition head; the primary auxiliary air hole 44 is connected to a primary air inlet pipe 53, and the other end of the primary air inlet pipe 53 is connected to the primary air annular tube channel 54, and the primary air annular tube channel 54 is fixed to the disturbance wind annular tube channel 62 through an auxiliary air tube bracket 55. The primary air annular tube channel 54 is also provided with a primary air inlet hole 56; the disturbance wind annular tube channel 62 is directly connected to the disturbance wind inlet pipe group 61, and the other end of the disturbance wind inlet pipe group 61 is connected to the secondary auxiliary air On the hole group 45, the secondary auxiliary air hole group 45 includes a 45° downward blowing disturbance hole 57, a 45° rightward blowing disturbance hole 58, a 45° leftward blowing disturbance hole 59, and an upward blowing disturbance hole 60. The upper part of the disturbance wind annular tube channel 62 is also provided with a disturbance wind air inlet hole 63; the tertiary auxiliary air hole 46 is connected to the rectified air annular tube channel 65 provided with the rectified air inlet hole 66 through the rectified air inlet pipe 64, and the rectified air annular tube channel 65 is fixed to the outside of the primary air annular tube channel 54 through the auxiliary air pipe bracket 55; the quaternary auxiliary air hole 48 is connected to the regulating air annular tube channel 68 provided with the regulating air inlet hole 69 through the regulating air inlet pipe 67, and the regulating air annular tube channel 68 is fixed to the outside of the rectified air annular tube channel 65 through the auxiliary air pipe bracket 55.

[0059] Reference Figure 1The primary push-flow auxiliary air pipeline 11 is provided with a push-flow air path electromagnetic valve 22, a push-flow air path flowmeter 23, and a push-flow terminal connecting pipe 24 in sequence, and the other end of the push-flow terminal connecting pipe 24 is connected to the push-flow air inlet hole 56 provided on the inner hollow truncated cone-shaped deposition head 21; the secondary disturbance auxiliary air pipeline 12 is provided with a disturbance air path electromagnetic valve 25, a disturbance air path flowmeter 26, and a disturbance terminal connecting pipe 27 in sequence, and the other end of the disturbance terminal connecting pipe 27 is connected to the disturbance air inlet hole 63 provided on the inner hollow truncated cone-shaped deposition head 21 ; The tertiary rectification auxiliary air pipeline 13 is provided with a rectification air path solenoid valve 28, a rectification air path flowmeter 29, and a rectification terminal connecting pipe 30 in sequence, and the other end of the rectification terminal connecting pipe 30 is connected to the rectification air inlet hole 66 provided on the inner hollow conical deposition head 21; the fourth regulation auxiliary air pipeline 14 is provided with a regulation air path solenoid valve 31, a regulation air path flowmeter 32, and a regulation terminal connecting pipe 33 in sequence, and the other end of the regulation terminal connecting pipe 33 is connected to the regulation air inlet hole 69 provided on the inner hollow conical deposition head 21.

[0060] like Figure 1 As shown, the regulation system circuit 2 is used to adjust the flow rate of each air path and the power of the periodic electric motor. One end of the regulation system circuit 2 is connected to the computer host 38, and the other end is connected to the main air path solenoid valve 7, the powder delivery air path solenoid valve 15, the push flow air path solenoid valve 22, the disturbance air path solenoid valve 25, the rectifier air path solenoid valve 28, the control air path solenoid valve 31, the periodic electric motor 52 and the electromagnetic valve 39 through the aviation plug; the computer host 38 is also connected to the measurement feedback system circuit 3, which is mainly used to measure and feedback the distribution characteristics of powder particles in the space below the deposition head. The other end of the regulation system circuit 2 is connected to the high-magnification camera 35. A light sheet 37 is provided on the far end of the concentric axis of the high-magnification camera 35, and an auxiliary laser source 36 is placed behind the light sheet 37.

[0061] In this embodiment, the flow meters are used to monitor the flow of fluids, and the solenoid valves are used to adjust the flow and speed of gases.

[0062] In this embodiment, the particle size of the metal powder ranges from 30 μm to 150 μm, and the transmission speed of the metal powder particles ranges from 1 g / s to 10 g / s.

[0063] A direct laser deposition system method for controlling powder transfer optimization of the present invention comprises the following steps:

[0064] Step 1: Implementation of direct laser deposition basic / variable powder transfer process:

[0065] I. Open the ball valve 5 to allow the inert gas in the high-pressure gas tank 4 to flow into the buffer tank 6 for buffering and preparation for use; II. Open the main air path solenoid valve 7 to allow the air flow to flow through the main air path flow meter 8 and then flow into the six-way interface 9; III. Regulate the periodic electric motor 52 to make the mechanical dispersion fan 51 in a vertical state so that the tangential direction of the blade surface is consistent with the particle transfer direction; IV. Open the powder delivery air path solenoid valve 15, and the air flow can flow through the powder delivery pipeline 10 and the powder delivery air path flow meter 16 and then flow into the air-powder mixing tank 19. At this time, the solenoid valve 39 is opened synchronously to allow the powder material to The powder particles fall from the material tank 17 into the air-powder mixing tank 19 via the pipeline 18; V. After being evenly mixed with the powder delivery air, the powder particles are delivered into the annular powder delivery cavity 40 of the hollow conical deposition head 21 through the powder delivery end connecting pipe 20 and the powder inlet 42 provided on the annular disc-shaped end cover 41, and are then delivered to the workbench 34 through the bottom outlet of the cavity, and the layer manufacturing process is completed after coupling with the laser emitted by the laser emission head 50; VI. The powder delivery air path solenoid valve 15 and the solenoid valve 39 are matched and controlled by the computer host 38 to achieve powder transfer under different working conditions.

[0066] Step 2: Measurement of the spatial distribution characteristics of powder concentration in the area below the deposition head:

[0067] I. Turn on the auxiliary laser source 36 and adjust the position of the high-magnification camera 35 so that the light beam after passing through the light sheet 37 is located on the center line of the high-magnification camera 35; II. Turn on the high-magnification camera 35 to continuously expose the powder particle group in the space below the hollow conical deposition head 21 in the direction perpendicular to the flow, and transmit the image data to the computer host 38; III. Use Mie theory to analyze and obtain the particle concentration at a fixed position in the space below the deposition head 21; IV. Synchronously move the auxiliary laser source 36 vertically, adjust the high-magnification camera 35 and the light sheet 37, and measure and analyze the particle concentration at each position.

[0068] Step 3: Control of the Direct Laser Deposition Powder Transfer Process

[0069] I. Turn on the periodic electric motor 52 to make the mechanical dispersion fan 51 do pendulum motion around its end axis, continuously breaking up the powder particle group introduced into the annular powder feeding cavity 40 from the powder inlet 42, so that the powder is dispersed in the annular cavity 40, and the powder flow is distributed more evenly within the circumference; II. Open the push flow air path solenoid valve 22 to allow the primary auxiliary air flow to enter the annular cavity 40 through the push flow air path flowmeter 23, the push flow terminal connecting pipe 24 and the push flow air inlet hole 56 to push the powder particles to continue to move downward rapidly; III. Open the disturbance air path solenoid valve 25 to allow the secondary disturbance air flow to enter the annular powder feeding cavity 40 through the disturbance air path flowmeter 26, the disturbance terminal connecting pipe 27 and the disturbance air inlet hole 63 to contact the powder particles introduced by II. The powder particle flow transmitted from III is subjected to fluid disturbance and secondary dispersion to further adjust the uniformity of the circumferential distribution of the powder flow; IV. The rectifying air path solenoid valve 28 is opened to allow the tertiary rectified air flow to pass through the rectifying air path flowmeter 29, the rectifying end connecting pipe 30 and the rectifying air inlet hole 66 into the annular cavity 40, and the semicircular protrusion group 47 is combined to perform continuous sinusoidal rectification on the turbulent powder flow transmitted from III to restore the turbulent flow to a laminar state; V. The regulating air path solenoid valve 31 is opened to allow the quaternary regulated air flow to pass through the regulating air path flowmeter 32, the regulating end connecting pipe 33 and the regulating air inlet hole 69 into the annular cavity 40, perform speed regulation on the laminar powder flow transmitted from IV, and adjust the position of the powder flow convergence plane.

[0070] Step 4: Optimization of the Direct Laser Deposition Powder Transfer Process

[0071] I. Based on the spatial distribution results of the powder flow measured by the high-magnification camera 35 in step 2, the powder distribution uniformity and the required convergence surface information are fed back to the computer host 38 in combination with the position of the workbench 34; II. Adjust the power of the periodic electric motor 52 and the opening of the disturbance air path solenoid valve 25 to optimize the uniformity of the powder flow distribution within the circumference; III. Adjust the push flow air path solenoid valve 22, the rectifier air path solenoid valve 28, and the control air path solenoid valve 31 to optimize the position of the powder flow convergence plane and the neck length of the convergence surface; IV. Use the high-magnification camera 35 to measure the spatial distribution results of the powder flow again, and repeat steps II to IV until the optimization adjustment is completed.

Claims

1. A direct laser deposition system with optimized and controllable powder delivery, characterized in that: include: A main air duct (1) is used for powder conveying and cascade air supply, comprising a high-pressure gas tank (4), a ball valve (5), a buffer tank (6), a main air duct solenoid valve (7), a main air duct flow meter (8), and a six-way interface (9) connected in sequence; the six-way interface (9) is respectively connected to: a powder delivery duct (10), a primary push flow auxiliary air duct (11), a secondary disturbance auxiliary air duct (12), a tertiary rectification auxiliary air duct (13), and a quaternary control auxiliary air duct (14); A regulating system circuit (2) is used to control the electric motor and the flow rate of each level of the air path, one end of which is connected to the computer host (38), and the other end is connected to the main air path solenoid valve (7), the powder delivery air path solenoid valve (15), the push flow air path solenoid valve (22), the disturbance air path solenoid valve (25), the rectifier air path solenoid valve (28), the control air path solenoid valve (31), and the periodic electric motor (52) through the aviation plug; A measurement feedback system circuit (3) is used to measure the particle distribution in the deposition head outlet space and provide reference and feedback for the control system, one end of which is connected to a computer host (38) and the other end is connected to a high-power camera (35); a light sheet (37) is provided at the distal end of the coaxial axis of the high-power camera (35), and an auxiliary laser source (36) is placed behind the light sheet (37); An inner hollow conical deposition head (21) is provided with a workbench (34) below the inner hollow conical deposition head (21); the inner hollow conical deposition head (21) includes an annular powder feeding cavity (40); a circular disk-shaped end cover (41) is provided on the top of the annular powder feeding cavity (40), and a powder inlet (42) is provided on the circular disk-shaped end cover (41); an axial hole (43), a primary auxiliary air hole (44), a secondary auxiliary air hole group (45), a tertiary auxiliary air hole (46), a semicircular protrusion group (47) and a quaternary auxiliary air hole (48) are provided on the outer wall block of the annular powder feeding cavity (40) in order from top to bottom; a laser bracket (49) is installed on the inner wall of the inner wall block of the annular powder feeding cavity (40), and a laser emitting head (50) is placed on the laser bracket (49).

2. A direct laser deposition system with optimized and controllable powder transfer according to claim 1, characterized in that: The powder delivery pipeline (10) is connected in sequence with: a powder delivery air path electromagnetic valve (15), a powder delivery air path flow meter (16), an air-powder mixing tank (19), and one end of a powder delivery end connecting pipe (20); the other end of the powder delivery end connecting pipe (20) is directly connected to a powder inlet (42); the air-powder mixing tank (19) is also provided with a pipeline (18) connected to a material tank (17), and a solenoid valve (39) is provided on the pipeline.

3. The direct laser deposition system with optimized and controllable powder transfer according to claim 1, characterized in that: The primary auxiliary air hole (44) is connected to a primary air inlet pipe (53), and the other end of the primary air inlet pipe (53) is connected to the primary air annular tube channel (54); the primary air annular tube channel (54) is fixed to the disturbance air annular tube channel (62) through an auxiliary air pipe bracket (55), and the primary air annular tube channel (54) is also provided with a primary air inlet hole (56); the disturbance air annular tube channel (62) is directly connected to the disturbance air inlet pipe group (61), and the other end of the disturbance air inlet pipe group (61) is connected to the secondary auxiliary air hole group (45); the secondary auxiliary air hole group (45) includes a downward 45° blowing disturbance hole (57), a rightward 45° blowing disturbance hole (58), a leftward 45° blowing disturbance hole (59), and a rightward 45° blowing disturbance hole (51). 9), an upward 45° blowing disturbance hole (60); a disturbance air inlet hole (63) is also provided on the upper part of the disturbance air annular tube channel (62); the tertiary auxiliary air hole (46) is connected to the rectification air annular tube channel (65) provided with the rectification air inlet hole (66) through the rectification air inlet pipe (64), and the rectification air annular tube channel (65) is fixed to the outside of the primary air annular tube channel (54) through the auxiliary air pipe bracket (55); the quaternary auxiliary air hole (48) is connected to the regulating air annular tube channel (68) provided with the regulating air inlet hole (69) through the regulating air inlet pipe (67), and the regulating air annular tube channel (68) is fixed to the outside of the rectification air annular tube channel (65) through the auxiliary air pipe bracket (55).

4. The direct laser deposition system with optimized and controllable powder transfer according to claim 1, characterized in that: The primary push-flow auxiliary air pipeline (11) is provided with: a push-flow air path electromagnetic valve (22), a push-flow air path flowmeter (23), and one end of a push-flow terminal connecting pipe (24), and the other end of the push-flow terminal connecting pipe (24) is connected to a primary air inlet hole (56) provided on the hollow truncated cone-shaped deposition head (21); the secondary disturbance auxiliary air pipeline (12) is provided with: a disturbance air path electromagnetic valve (25), a disturbance air path flowmeter (26), and one end of a disturbance terminal connecting pipe (27), and the other end of the disturbance terminal connecting pipe (27) is connected to a disturbance air inlet hole (63) provided on the hollow truncated cone-shaped deposition head (21). The three-stage rectifying auxiliary air pipeline (13) is provided with: a rectifying air path electromagnetic valve (28), a rectifying air path flow meter (29), and one end of a rectifying terminal connecting pipe (30), and the other end of the rectifying terminal connecting pipe (30) is connected to a rectifying air inlet hole (66) provided on the inner hollow truncated cone-shaped deposition head (21); the four-stage regulating auxiliary air pipeline (14) is provided with: a regulating air path electromagnetic valve (31), a regulating air path flow meter (32), and one end of a regulating terminal connecting pipe (33), and the other end of the regulating terminal connecting pipe (33) is connected to a regulating air inlet hole (69) provided on the inner hollow truncated cone-shaped deposition head (21); The shaft hole (43), the primary auxiliary air hole (44), the secondary auxiliary air hole group (45), the tertiary auxiliary air hole (46), and the quaternary auxiliary air hole (48) are evenly distributed on the outer wall of the annular powder feeding cavity (40) at periods of 90°, 90°, 30°, 60°, and 90°, respectively.

Images