Laser selective melting chamber wind speed vector measuring device and method

Abstract

The application provides a laser selective melting chamber wind speed vector measuring device and method. The device comprises a base and three sensing arm assemblies installed on the base; the measuring centers of the wind sensing sheets of the three sensing arm assemblies are arranged on the same line along the transverse movement direction of the doctor blade, and the distance between adjacent measuring centers is determined according to the condition that no interference occurs during measurement. The base is installed on the doctor blade of a laser selective melting device, the measuring centers of the three wind sensing sheets pass through the same to-be-measured point in sequence by controlling the movement of the doctor blade along the X axis, the wind speed components in three orthogonal directions of the to-be-measured point are obtained under a steady or quasi-steady wind field, and then the total speed vector is obtained by vector synthesis. The application realizes physical decoupling of the measurement channels in different directions through a mechanical structure, and completes the measurement of the same point by using the original movement mechanism of the doctor blade, without the need of adding a special driving mechanism, so that the structure is compact, the friction interference is small, and the in-situ measurement of the airflow speed vector in the forming chamber is suitable.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing process monitoring technology, and more specifically, to a device and method for measuring wind speed vector in a laser selective melting chamber. Background Technology

[0002] Selective laser melting (SLM), an important metal additive manufacturing technology, requires a chamber filled with an inert protective gas to prevent metal powder oxidation during the forming process. The flow state of the protective gas flow, including its velocity and direction, directly affects the efficiency of dust and spatter removal, the stability of oxygen content control, and the metallurgical quality of the formed parts. Ideally, the gas flow should be a smooth, uniform laminar flow. However, the airflow distribution within the forming chamber is often non-uniform, with differences in airflow velocity and direction at different locations. If the airflow velocity in certain areas is too low or the direction is incorrect, spatter may not be effectively removed, thus affecting the density and surface quality of the parts. Therefore, accurate measurement of the airflow velocity vector at specific locations within the forming chamber, especially near the laser scanning area, is crucial for optimizing process parameters and improving forming quality.

[0003] Currently, commonly used airflow measurement methods mainly include qualitative observation and single-component measurement. Qualitative observation involves placing small, lightweight objects, such as feathers or smoke trails, and observing their drift with the airflow. This method can only provide a rough qualitative observation of the flow trend and cannot obtain precise, quantitative velocity data. Single-component measurement uses anemometers to measure the airflow. Some anemometers, such as thermal anemometers, can only measure the magnitude of the airflow velocity and cannot simultaneously acquire airflow direction information, making it difficult to comprehensively assess the three-dimensional flow field structure. These traditional methods typically only measure the wind speed in a single direction and cannot simultaneously obtain three-dimensional velocity vector information of the airflow. Furthermore, existing measurement devices are relatively large, making it difficult to install them in the space-constrained forming chamber of laser selective melting equipment for in-situ measurements.

[0004] In other sensor technology fields, there are also sensors for measuring three-dimensional force or displacement. For example, Chinese patent documents with publication number CN109115380A and application number CN201710484808.5 disclose a three-dimensional force sensor for minimally invasive medical devices. This sensor adopts a coaxial composite elastomer structure composed of a leaf spring, a slotted outer tube, an inner tube, and multiple optical fibers. It measures the complex strain of the structure after being subjected to force and uses a matrix decoupling algorithm or machine learning method to inversely deduce the three-dimensional contact force.

[0005] The aforementioned three-dimensional force sensor is designed to measure contact forces between solids, and its core components are an integral elastomer and a complex strain-sensing structure. However, directly applying it to measure airflow velocity vectors within a laser selective melting chamber presents the following problems: its structure cannot directly convert fluid momentum into a measurable axial force; its signal processing relies on a complex decoupling model established for a specific solid elastomer, resulting in poor adaptability to changes in the flow field; furthermore, its structure is difficult to miniaturize, making multi-point deployment within the forming chamber of a laser selective melting device inconvenient. Therefore, this type of three-dimensional force sensor cannot directly solve the problem of independently and directly measuring the velocity components of the airflow in the three orthogonal directions.

[0006] Therefore, there is an urgent need to develop a miniaturized, dedicated measuring device capable of measuring three-dimensional wind speed vectors and ensuring that measurement results in three directions correspond to the same measurement point. This device should also utilize the existing motion mechanism of the laser selective melting equipment as much as possible to complete the measurement, avoiding the need for an additional dedicated drive mechanism. Summary of the Invention

[0007] (a) Technical problems to be solved The technical problem to be solved by this invention is that traditional methods can usually only measure the wind speed in a single direction, and it is difficult to obtain the three-dimensional velocity vector information of the airflow at the same time; existing measuring devices are large in size and difficult to install in the forming chamber of laser selective melting equipment with limited space for in-situ measurement; in addition, if the three measuring sensors are located in different spatial positions, the measurement results in the three directions may not correspond to the same measurement point.

[0008] (II) Technical Solution To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a wind speed vector measuring device for a laser selective melting chamber, comprising a base, a support rod, and three sensing arm assemblies; the base is mounted on a scraper slide, and the support rod is connected to the base; the three sensing arm assemblies are connected to the support rod and extend from the support rod along three mutually orthogonal coordinate axes; each sensing arm assembly includes a measuring arm, a micro-force sensor, a sleeve rod, and a wind-sensing plate; the axes of the three measuring arms are respectively aligned with their corresponding coordinate axes, the measuring arms have an axially formed inner hole, and the outer wall of the sleeve rod is perpendicular to the inner hole of the measuring arm. The inner wall slides together, and the sleeve rod is made of a self-lubricating material. One end of the micro-force sensor is connected to the sleeve rod, and the other end of the micro-force sensor is connected to the bottom of the inner hole of the measuring arm. The wind sensor is fixedly connected to the sleeve rod, and the plane of the wind sensor is perpendicular to the axis of the connecting section between the measuring arm and the wind sensor. The measuring centers of the wind sensors of the three sensing arm assemblies are arranged on the same straight line along the X direction. There is a preset distance between the measuring centers of the three wind sensors. The preset distance is based on the premise that no significant airflow interference is generated between the wind sensors during the measurement process.

[0009] Specifically, in this invention, the following coordinate system is established: the length direction of the scraper slide itself is the Y direction, the lateral powder-spreading movement direction of the scraper slide is the X direction, and the vertical direction is the Z direction. Three sensing arm assemblies are used to acquire the airflow velocity components in the X, Y, and Z directions, respectively. Each sensing arm assembly includes a measuring arm, a micro-force sensor, a sleeve rod, and a wind-sensing plate; the axis of the measuring arm is consistent with the corresponding coordinate axis direction, the measuring arm has an inner hole along the axial direction, the outer wall of the sleeve rod slides against the inner wall of the inner hole, and the sleeve rod is made of a self-lubricating material; one end of the micro-force sensor is connected to the sleeve rod, and the other end of the micro-force sensor is connected to the bottom of the inner hole of the measuring arm; the wind-sensing plate is fixedly connected to the sleeve rod, and the plane of the wind-sensing plate is perpendicular to the axis of the measuring arm segment connected to it. The three sensing arm assemblies are respectively installed at different positions on the base, and through an L-shaped design, the measuring centers of the three wind-sensing plates are aligned on the same straight line along the X direction. The distance between the three measurement centers is determined based on the size of the sensing plates, the characteristics of the flow field to be measured, and the required measurement accuracy, ensuring that no significant airflow interference occurs between the three sensing plates during the measurement process. The base is mounted on the scraper slide of the laser selective melting equipment. By controlling the scraper slide to move along the X direction, the measurement centers of the three sensing plates sequentially pass through the same measurement point. Although the three sensing plates do not pass through the measurement point simultaneously, this invention performs measurements under steady-state or quasi-steady-state wind fields, preferably when the equipment is not printing. Under these conditions, the wind field to be measured can be considered time-independent within the measurement time range. Therefore, the three directional velocity components obtained sequentially by the three sensing arm assemblies can be vector-synthesized as the X, Y, and Z directional velocity components of the same measurement point.

[0010] Preferably, the wind sensor is a circular plate. Using a circular plate makes the force characteristics of the wind sensor more uniform in all directions, which helps to simplify the calibration process and improve measurement accuracy.

[0011] Preferably, the self-lubricating material is polytetrafluoroethylene, nylon, or polyetheretherketone. These materials have good self-lubricating properties, which can effectively reduce the friction between the sleeve rod and the inner wall of the measuring arm, thereby reducing the interference of mechanical friction on the measurement results of the micro-force sensor and improving the measurement accuracy.

[0012] Preferably, the micro-force sensor is a rod-shaped strain sensor, and the diameter of the micro-force sensor is smaller than the inner diameter of the measuring arm. This structural design allows the micro-force sensor to be housed in a hole inside the measuring arm, thereby achieving miniaturization of the sensing arm assembly. More preferably, the micro-force sensor is a fiber Bragg grating strain sensor. Fiber Bragg grating sensors have advantages such as resistance to electromagnetic interference, high sensitivity, and small size, making them suitable for the complex environment inside laser selective melting equipment.

[0013] Preferably, the three sensing arm assemblies are respectively installed at different positions on the base, and through an L-shaped design, the measurement centers of the three wind-sensing plates are aligned on the same straight line along the X direction.

[0014] The length of the measuring arm is preferably no more than 10 mm. By controlling the length of the measuring arm to a shorter range, the disturbance of the device to the original flow field can be reduced, and the distance between the measuring centers of the three wind vanes can be kept within a range suitable for not causing significant mutual interference.

[0015] Preferably, the system further includes a data acquisition and processing module, which is connected to the micro-force sensor signals. This module receives signals from each micro-force sensor and calculates the velocity components of the airflow along the three coordinate axes (X, Y, and Z) according to a preset calibration relationship. The resulting total velocity vector is then synthesized. Specifically, the total velocity vector is calculated using the formula V = (Vx² + Vy² + Vz²)¹ / ². The airflow direction can be determined using direction cosines.

[0016] Preferably, the device further includes a fixing component for mounting the base onto the scraper slide of the laser selective melting equipment. The scraper slide's length direction is the Y-direction, its lateral movement direction is the X-direction, and the scraper slide drives the three air-sensing plates to move along the X-direction. Specifically, the fixing component can be in the form of a magnetic base, bolted connector, or vacuum adsorption plate for easy installation and disassembly.

[0017] This invention, through three mutually orthogonal wind-sensing vanes and their corresponding axial sliding structures, decomposes incoming airflow from any direction into axial forces in three directions at the mechanical structure level. For each sensing arm assembly, the wind-sensing vane plane is perpendicular to the corresponding measuring arm axis. The component of the airflow in that axial direction is received by the sensor as an axial force, while the tangential component parallel to the wind-sensing vane plane is neglected by the sensor. The sleeve rod restricts the radial offset of the wind-sensing vanes and the micro-force sensor, allowing the micro-force sensor to primarily bear the axial force. Therefore, the output of each micro-force sensor can directly correspond to the velocity component in the corresponding direction, eliminating the need for complex matrix decoupling algorithms or machine learning algorithms specific to the overall elastic structure.

[0018] Secondly, the present invention also provides a method for measuring airflow velocity vector using the laser selective melting chamber wind speed vector measuring device, comprising the following steps: The wind speed vector measuring device for the laser selective melting chamber is installed on the scraper slide of the laser selective melting equipment, and the three wind sensors are exposed to the flow field to be measured. Control the scraper slide to move along the X direction so that the measurement centers of the three wind-sensing plates pass through the same measurement point in the flow field to be measured in sequence; When the measurement centers of the three wind-sensing plates pass through the points to be measured, the scraper slide movement is temporarily stopped. After the nearby airflow stabilizes, the corresponding micro-force sensors sense the axial force generated by the airflow acting on the corresponding wind-sensing plates and output the corresponding electrical signals. Based on the electrical signals from the three micro-force sensors, and using the pre-calibrated relationship, the velocity components of the airflow at the test point in the three orthogonal coordinate axes are calculated respectively. Under the condition that the airflow to be measured is in a steady state or quasi-steady state, the three velocity components are vector-synthesized as the velocity components of the same measurement point to obtain the magnitude and direction of the total airflow velocity at the measurement point.

[0019] Preferably, the measurement is performed when the laser selective melting equipment is not printing, so as to avoid the influence of laser scanning, powder laying, smoke and splashing during the printing process on the measurement results.

[0020] Preferably, the movement of the scraper drag plate along the X direction is achieved by the original powder spreading motion control mechanism of the laser selective melting equipment, without the need for a separate drive mechanism to drive the measuring device.

[0021] Preferably, the pre-calibrated calibration relationship is obtained by placing the laser selective melting chamber wind speed vector measuring device in a standard wind tunnel with a known flow velocity, and allowing the airflow to sequentially blow towards the corresponding wind-sensing plates along the three coordinate axes. The calibration relationship is used to convert the electrical signals output by each micro-force sensor into airflow velocity components in the corresponding coordinate axis directions, without requiring complex mathematical decoupling between the velocity components in the three directions through an overall three-dimensional force matrix. Specifically, the device is placed in a standard wind tunnel with a known flow velocity, and the airflow is sequentially blown towards the corresponding wind-sensing plates along the X, Y, and Z coordinate axes. The output signals of each micro-force sensor under different standard wind velocities are recorded, and a "wind speed-signal" calibration curve or calibration equation is established for each direction.

[0022] (III) Beneficial Effects The above-described technical solution of the present invention has at least the following advantages: 1. This invention, by setting up sensing arm assemblies for measuring the velocity components in the three orthogonal directions (X, Y, and Z), can obtain complete three-dimensional airflow velocity vector information, overcoming the limitation of traditional single-point anemometers that can only measure wind speed in a single direction. The unique "measuring arm-sleeve-sensor plate" structure ensures that the plane of the sensor plate is perpendicular to the axis of the measuring arm, and the airflow force on the sensor plate is mainly transmitted to the micro-force sensor along the axial direction of the measuring arm, avoiding or reducing the influence of bending moment and lateral force.

[0023] 2. Unlike sensors used for solid contact force measurement that require complex matrix decoupling algorithms or machine learning methods to infer three-dimensional force, this invention achieves physical decomposition of directional components at the mechanical structure level through mutually orthogonal wind-sensing plates and axial sliding structures. The output of each micro-force sensor directly corresponds to the airflow velocity component in one direction. The signal processing is simple, and the real-time performance and anti-interference ability are high.

[0024] 3. This invention effectively reduces mechanical friction loss during force transmission of the wind sensor by setting a sliding sleeve rod inside the measuring arm and making the sleeve rod with a self-lubricating material, thereby improving the measurement sensitivity and accuracy of the micro-force sensor.

[0025] 4. This invention arranges the measurement centers of three wind sensors along the X-direction on the same straight line, and mounts the measuring device on the scraper slide. Through the normal movement of the scraper slide along the X-direction, the three measurement centers sequentially pass through the same measurement point. Under steady-state or quasi-steady-state wind field conditions, the velocity components obtained by the three sensors can correspond to the same spatial measurement point, thus avoiding the problem of inconsistent measurement points caused by the three wind sensors being in different spatial positions.

[0026] 5. This invention utilizes the existing scraper slide motion control mechanism of the laser selective melting equipment to achieve sequential positioning of the three measurement centers, eliminating the need for an additional independent drive mechanism. The structure is simple, the implementation is convenient, and it can reduce the complexity of the device and manufacturing costs.

[0027] 6. The sensing arm assembly of this invention has a compact structure, with a measuring arm length not exceeding 10mm. The overall device is small in size, causing minimal interference to the original flow field. It is suitable for installation in space-constrained environments such as the forming chamber of laser selective melting equipment, enabling in-situ measurement. By controlling the movement of the scraper slide at different positions, airflow vector distribution maps at multiple key locations within the forming chamber can also be obtained, providing a testing tool for flow field evaluation and optimization. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the wind speed vector measuring device for laser selective melting chamber provided in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the sensor arm assembly provided in an embodiment of the present invention.

[0031] Figure 3 This is a perspective structural diagram of the sensing arm assembly provided in an embodiment of the present invention.

[0032] The labels for the attached figures are as follows: 100. Laser selective melting chamber; 110. Air inlet; 120. Air inlet; 130. Signal cable hole; 1. Base; 2. Support rod; 3. Sensor arm assembly; 31. Measuring arm; 32. Micro-force sensor; 33. Sleeve rod; 34. Air sensor; 35. Measuring center of air sensor; 4. Scraper slide; 5. Data acquisition and processing module; 51. Signal harness. Detailed Implementation

[0033] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0034] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0035] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0036] The specific implementation of the present invention will be described in more detail below with reference to specific embodiments: Example 1 like Figure 1 and Figure 2 As shown, this embodiment provides a wind speed vector measurement device for a laser selective melting chamber, including a base 1, a support rod 2, and three sensor arm assemblies 3. The support rod 2 and the three sensor arm assemblies 3 are respectively installed at different positions on the base 1 and are used to measure the airflow velocity components in the X-axis, Y-axis, and Z-axis directions. The Z-axis support rod coincides with the axis of the Z-axis measuring arm. The X-axis and Y-axis support rods are perpendicular to their corresponding measuring arms, forming an L-shape.

[0037] In this embodiment, three sensor arm assemblies 3 are installed at intervals along the X-direction. Through an L-shaped design, the measurement centers 35 of the wind-sensing plates 34 of the three sensor arm assemblies 3 are aligned along the X-direction in a straight line. The distance between the three measurement centers 35 is determined based on the size of the wind-sensing plates 34, the airflow velocity, and the flow field interference, ensuring that there is no significant mutual interference during measurement.

[0038] The base 1 is mounted on the scraper slide 4. The scraper slide 4 is oriented along the Y-axis and moves laterally along the X-axis to complete the powder spreading action of the laser selective melting equipment. During measurement, by controlling the scraper slide 4 to move along the X-axis, the measurement centers 35 of the three air sensors 34 are sequentially passed through the same measurement point. Since the three measurement centers 35 are arranged along the X-axis, when the scraper slide 4 moves along the X-axis, the three measurement centers 35 can pass through the same spatial position sequentially.

[0039] Please refer to the following: Figure 3Each sensing arm assembly 3 includes a measuring arm 31, a micro-force sensor 32, a sleeve rod 33, and a wind sensor 34. The measuring arm 31 is a hollow tubular component, meaning that the measuring arm 31 has an inner hole along its axial direction, and the section of its axis connected to the wind sensor is aligned with the corresponding coordinate axis. For sensing arm assemblies with different orientations, the measuring arm 31 can be installed at different positions on the base 1 via an L-shaped connection, while simultaneously maintaining the measuring arm 31 extending along the X-axis, Y-axis, and Z-axis directions respectively.

[0040] The outer diameter of the sleeve rod 33 matches the inner diameter of the inner hole of the measuring arm 31, allowing the sleeve rod 33 to slide freely axially within the hole of the measuring arm 31. The sleeve rod 33 is made of a self-lubricating material, such as polytetrafluoroethylene, nylon, or polyetheretherketone, to reduce sliding friction resistance. Specifically, the measuring arm 31 can be made of a stainless steel thin tube with an inner diameter of 0.6 mm and an outer diameter of 1 mm, and the length of the measuring arm 31 in all three directions is 8 mm.

[0041] A micro-force sensor 32 is disposed within the inner bore of the measuring arm 31. One end of the micro-force sensor 32 is connected to the sleeve rod 33, and the other end is connected to the bottom of the inner bore of the measuring arm 31. When the sleeve 33 is subjected to an axial force, the micro-force sensor 32 will undergo corresponding deformation or strain, thereby outputting an electrical signal corresponding to the magnitude of the force. In this embodiment, the micro-force sensor 32 is preferably a rod-shaped strain sensor with a diameter smaller than the inner diameter of the measuring arm 31 to ensure that it can be accommodated inside the measuring arm 31 without interference. More preferably, the micro-force sensor 32 is a fiber optic strain sensor to improve electromagnetic interference resistance and sensitivity.

[0042] The wind sensor 34 is fixedly connected to the outer end of the sleeve rod 33, and the plane of the wind sensor 34 is perpendicular to the axis of the measuring arm 31 to which it is connected. In this embodiment, the wind sensor 34 is preferably a thin circular sheet to make its force characteristics more symmetrical when the flow is coming from different directions. The wind sensor 34 can be a stainless steel disc with a diameter of 3 mm and a thickness of 0.1 mm.

[0043] For the sensing arm assembly 3 installed along the X-axis, the plane of its wind-sensing plate 34 is perpendicular to the X-axis. When airflow from any direction in space blows toward the wind-sensing plate 34, the airflow vector can be decomposed into a component perpendicular to the plane of the wind-sensing plate 34, i.e., a component along the X-axis, and a tangential component parallel to the plane of the wind-sensing plate 34. Since the wind-sensing plate 34 is relatively thin, the tangential component does not generate axial force; the perpendicular component acts directly on the wind-sensing plate 34, pushing the wind-sensing plate 34 and the sleeve rod 33 fixedly connected to it to move axially along the measuring arm 31, thereby causing the micro-force sensor 32 to undergo a slight elongation or shortening deformation along its axial direction. The micro-force sensor 32 converts this deformation into a corresponding electrical signal output.

[0044] The sliding fit between the sleeve rod 33 and the inner wall of the measuring arm 31 restricts the radial displacement of the sleeve rod 33 and the wind-sensing vane 34, allowing the micro-force sensor 32 to primarily bear axial force and reducing the influence of lateral force and bending moment. By pre-calibrating the sensing arm assemblies in a standard wind tunnel, a correspondence between the electrical signal and the corresponding axial airflow velocity component can be established. Similarly, the sensing arm assemblies in the Y-axis and Z-axis directions acquire the airflow velocity components in the Y and Z directions, respectively.

[0045] In this embodiment, the three wind sensors 34 are not located in the same spatial position simultaneously, but are arranged along the X direction. During measurement, the scraper slide 4 drives the three wind sensors 34 to move along the X direction, so that the measurement centers 35 of the three wind sensors 34 pass through the same measurement point in sequence. Since the measurement is performed under steady-state or quasi-steady-state airflow conditions, and preferably when the laser selective melting equipment is not printing, the wind field to be measured can be considered to be basically constant during the time interval between the three measurement centers 35 passing through the measurement point. Therefore, the three directional velocity components obtained by the three micro-force sensors 32 at different times can correspond to the X, Y, and Z directional velocity components at the same measurement point.

[0046] like Figure 1 As shown, the electrical signals output by each micro-force sensor 32 are transmitted to the data acquisition and processing module 5 via signal line 51. The data acquisition and processing module 5 calculates the wind speed components Vx, Vy, and Vz in the three directions based on the calibration curves of each sensor, then calculates the total wind speed using a vector synthesis formula, and determines the wind direction angle using the direction cosine. Specifically, a signal line hole 130 is provided on the laser selective melting chamber 100 for threading the signal line 51.

[0047] The device in this embodiment also includes a fixing component, which is mounted on the base 1 and is used to detachably mount the entire device onto the scraper slide 4. The fixing component can be a magnetic base, a threaded connector, a bolt connector, or other detachable connection structure. Since the scraper slide 4 itself has a control mechanism for movement in the X direction, the present invention does not require adding a separate drive mechanism to the measuring device.

[0048] Example 2 This embodiment provides a method for measuring airflow velocity vector using the device described in Embodiment 1, including the following steps: First, according to the coordinate system definition, the length direction of the scraper slide 4 is taken as the Y direction, the lateral powder-spreading movement direction of the scraper slide 4 is taken as the X direction, and the vertical direction is taken as the Z direction. The three sensor arm assemblies 3 are adjusted to measure the airflow velocity components in the X, Y, and Z directions, and the three sensor arm assemblies 3 are installed at different positions on the base 1, so that the measurement centers 35 of the three air-sensing vanes 34 are aligned on the same straight line along the X direction.

[0049] Then, the base 1 is installed on the scraper slide 4 of the laser selective melting equipment, so that the three air-sensing plates 34 are fully exposed to the protective gas flow in the laser selective melting chamber 100. Preferably, when the equipment is not printing, a protective gas, such as argon, is introduced, and measurements are taken after the protective gas flow stabilizes.

[0050] Next, the data acquisition and processing module 5 is activated to control the scraper slide 4 to move along the X direction. The movement of the scraper slide 4 is achieved using the equipment's existing powder spreading motion control mechanism. As the scraper slide 4 moves, the measurement centers 35 of the three air sensors 34 sequentially pass through the same pre-selected measurement point.

[0051] When the measurement centers 35 of the three wind sensors 34 pass the point to be measured, their movement temporarily stops. After the interference caused by the movement of the wind sensors on the surrounding airflow disappears, the electrical signals output by the corresponding micro-force sensors 32 are collected. The signal amplitude of each micro-force sensor 32 has a functional relationship with the airflow velocity in its corresponding direction, obtained through wind tunnel calibration.

[0052] Subsequently, the data acquisition and processing module 5 converts the output signals of the three micro-force sensors 32 into wind speed components in the X, Y, and Z directions, respectively, according to the pre-stored calibration relationship. Since the measurement process is carried out under steady-state or quasi-steady-state wind field conditions, the velocity components acquired at three different times can be used as the three directional velocity components of the same measurement point.

[0053] Finally, the wind speed components in the three orthogonal directions are vector-synthesized to obtain the magnitude and direction of the total airflow velocity at the measurement point. The measurement results can be displayed in real time on the screen or saved as a data file for subsequent analysis.

[0054] In another embodiment, the position of the measurement point can be changed, and the scraper slide 4 can be repeatedly controlled to move along the X direction, so that the three measurement centers 35 pass through different measurement points in sequence, thereby obtaining the airflow velocity vector distribution of multiple areas in the forming chamber. The measurement points may include the four corners of the forming area, the position near the air inlet 120, the position near the air suction port 110, and the position near the laser scanning area.

[0055] Example 3 This embodiment performs wind tunnel calibration on the sensor.

[0056] Before use, place the entire measuring device in a standard wind tunnel with a known flow velocity. Blow the standard airflow along the X, Y, and Z coordinate axes toward the corresponding wind sensor 34, and record the electrical signal, wavelength drift, or strain output value of the corresponding micro-force sensor 32 at different standard wind velocities. Establish the "wind speed-signal" calibration curve or calibration equation for each direction.

[0057] In actual measurements, the data acquisition and processing module 5 calculates Vx based on the output signal from the X-direction sensor, Vy based on the output signal from the Y-direction sensor, and Vz based on the output signal from the Z-direction sensor. For example, the measured values ​​are: Vx = 0.5 m / s, Vy = -0.2 m / s, and Vz = 0.1 m / s, where the negative sign indicates that the corresponding direction is opposite to the positive direction of the coordinate axis. Subsequently, the resultant velocity is calculated according to the resultant velocity formula V = (Vx² + Vy² + Vz²)¹ / ², and the airflow direction vector and direction cosine are calculated based on the three velocity components.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vector measurement device for wind speed in a laser selective melting chamber, characterized in that, include: The base is mounted on the scraper slide; The support rod is connected at one end to the base and at the other end to the sensing arm assembly; Three sensing arm assemblies are connected to the support rod and extend from the support rod along three mutually orthogonal coordinate axes in space, respectively; Each of the sensor arm assemblies includes a measuring arm, a micro-force sensor, a sleeve rod, and a wind sensor. The axes of the three measuring arms are aligned with their corresponding coordinate axes. Each measuring arm has an axially oriented inner hole. The outer wall of the sleeve rod slides against the inner wall of the inner hole of the measuring arm. The sleeve rod is made of a self-lubricating material. One end of the micro-force sensor is connected to the sleeve rod, and the other end of the micro-force sensor is connected to the bottom of the inner hole of the measuring arm. The wind sensor is fixedly connected to the sleeve rod, and the plane of the wind sensor is perpendicular to the axis of the connection section between the measuring arm and the wind sensor. The measurement centers of the wind-sensing plates of the three sensing arm assemblies are arranged on the same straight line along the X direction, and there is a preset distance between the measurement centers of the three wind-sensing plates. The preset distance is based on the premise that no significant airflow interference is generated between the wind-sensing plates during the measurement process.

2. The laser selective melting chamber wind speed vector measuring device as described in claim 1, characterized in that, The wind-sensing plate is a circular plate.

3. The laser selective melting chamber wind speed vector measuring device as described in claim 1, characterized in that, The self-lubricating material is polytetrafluoroethylene, nylon, or polyetheretherketone.

4. The laser selective melting chamber wind speed vector measuring device as described in claim 1, characterized in that, The micro-force sensor is a rod-shaped strain sensor, and the diameter of the micro-force sensor is smaller than the inner diameter of the measuring arm.

5. The laser selective melting chamber wind speed vector measuring device as described in claim 1, characterized in that, The micro-force sensor is a fiber optic strain sensor.

6. The laser selective melting chamber wind speed vector measuring device as described in claim 1, characterized in that, The three sensing arm assemblies are respectively installed at different positions on the base, and through the L-shaped design, the measurement centers of the three wind-sensing plates are aligned on the same straight line along the X direction.

7. The laser selective melting chamber wind speed vector measuring device as described in claim 1, characterized in that, It also includes a data acquisition and processing module, which is connected to the micro-force sensor signal to receive the signals from each micro-force sensor and calculate the velocity components of the airflow in the three coordinate axes according to the preset calibration relationship, and then synthesize the total velocity vector.

8. The laser selective melting chamber wind speed vector measuring device as described in claim 7, characterized in that, It also includes a fixing component, which is used to install the base onto the scraper slide of the laser selective melting equipment. The scraper slide has its length direction in the Y direction and its lateral movement direction in the X direction. The scraper slide is used to drive the three air-sensing plates to move in the X direction.

9. A method for measuring airflow velocity vector using the airflow velocity vector measuring device for a laser selective melting chamber as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The wind speed vector measuring device for the laser selective melting chamber is installed on the scraper slide of the laser selective melting equipment, and the three wind sensors are exposed to the flow field to be measured. Control the scraper slide to move along the X direction so that the measurement centers of the three wind-sensing plates pass through the same measurement point in the flow field to be measured in sequence; When the measurement centers of the three wind-sensing plates pass through the points to be measured, the scraper slide movement is temporarily stopped. After the nearby airflow stabilizes, the corresponding micro-force sensors sense the axial force generated by the airflow acting on the corresponding wind-sensing plates and output the corresponding electrical signals. Based on the electrical signals from the three micro-force sensors, and using the pre-calibrated relationship, the velocity components of the airflow at the test point in the three orthogonal coordinate axes are calculated respectively. Under the condition that the airflow to be measured is in a steady state or quasi-steady state, the three velocity components are vector-synthesized as the velocity components of the same measurement point to obtain the magnitude and direction of the total airflow velocity at the measurement point.

10. The method as described in claim 9, characterized in that, The pre-calibrated calibration relationship is obtained by placing the laser selective melting chamber wind speed vector measuring device in a standard wind tunnel with a known flow velocity, and then calibrating the airflow by blowing it sequentially along the three coordinate axes towards the corresponding wind-sensing plates. The calibration relationship is used to convert the electrical signals output by each micro-force sensor into airflow velocity components in the corresponding coordinate axis directions. The velocity components in the three directions do not need to be decoupled by complex mathematics through the overall three-dimensional force matrix.

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