Beam monitoring device

Abstract

The utility model relates to a kind of light beam monitoring devices, and the device includes controller, laser, beamsplitter, dichroic mirror, scanning galvanometer, laser information monitoring device and molten pool information monitoring device;Beamsplitter is shaped laser emitted by laser into transmission light and reflection light;Laser information monitoring device is set on the light path of reflection light;Dichroic mirror and scanning galvanometer are sequentially set on the light path of transmission light from front to back;Transmission light after scanning galvanometer is incident to processing plane and is reflected to form processing feedback light by processing plane;Processing feedback light is incident to dichroic mirror after scanning galvanometer and is reflected by dichroic mirror to form processing reflection light;Molten pool information monitoring device is set on the light path of processing reflection light;Controller is connected with laser, laser information monitoring device, molten pool information monitoring device and scanning galvanometer respectively.The utility model has the advantages of being convenient for realizing accurate control, expanding process scene and improving forming quality.

Description

Technical Field

[0001] This utility model belongs to the field of additive manufacturing and relates to a beam monitoring device, and more particularly to a beam monitoring device for PBF. Background Technology

[0002] Conventional PBF (Powder Bed Fusion) optical paths set the laser power via a network connection, making it impossible to monitor the laser output power and monitor the molten pool radiation information via a coaxial optical path. This is not conducive to precise control of laser energy during the forming process. Utility Model Content

[0003] In order to solve the above-mentioned technical problems in the background art, the present invention provides a beam monitoring device that facilitates precise control, expands process scenarios, and improves forming quality.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A beam monitoring device, characterized in that: the beam monitoring device includes a controller, a laser, a beam splitter, a dichroic mirror, a scanning galvanometer, a laser information monitoring device, and a molten pool information monitoring device; the laser emits a forming laser; the beam splitter divides the forming laser into transmitted light and reflected light; the laser information monitoring device is disposed on the optical path of the reflected light; the dichroic mirror and the scanning galvanometer are disposed sequentially from front to back on the optical path of the transmitted light; the transmitted light after passing through the scanning galvanometer is incident on the processing plane and reflected by the processing plane to form processing feedback light; the processing feedback light after passing through the scanning galvanometer is incident on the dichroic mirror and reflected by the dichroic mirror to form processing reflected light; the molten pool information monitoring device is disposed on the optical path of the processing reflected light; the controller is connected to the laser, the laser information monitoring device, the molten pool information monitoring device, and the scanning galvanometer.

[0006] The aforementioned laser information monitoring device includes an attenuator and a laser status acquisition unit arranged sequentially from front to back along the optical path of the reflected light; the controller is connected to the laser status acquisition unit.

[0007] The aforementioned laser status acquisition unit is either a laser power acquisition unit or a laser information acquisition unit.

[0008] The aforementioned molten pool information monitoring device includes a focusing lens and a molten pool information acquisition unit arranged sequentially from front to back along the optical path of the processing reflected light; the controller is connected to the molten pool information acquisition unit.

[0009] The aforementioned beam monitoring device also includes an optical focusing element placed between the beam splitter and the dichroic mirror or between the scanning galvanometer and the processing plane.

[0010] When the aforementioned optical focusing element is placed between the beam splitter and the dichroic mirror, the optical focusing element is a dynamic focusing mirror; the beam splitter, the dynamic focusing mirror, the dichroic mirror, and the scanning galvanometer are arranged sequentially from front to back on the optical path where the transmitted light is located; the controller is connected to the dynamic focusing mirror.

[0011] When the aforementioned optical focusing element is placed between the scanning galvanometer and the processing plane, the optical focusing element is a field lens.

[0012] The aforementioned beam monitoring device also includes a beam expander; the beam expander and beam splitter are arranged sequentially from front to back along the optical path of the forming laser.

[0013] The advantages of this utility model are:

[0014] This invention provides a beam monitoring device, comprising a controller, a laser, a beam splitter, a dichroic mirror, a scanning galvanometer, a laser information monitoring device, and a molten pool information monitoring device. The laser emits a forming laser; the beam splitter divides the forming laser into transmitted light and reflected light; the laser information monitoring device is positioned on the optical path of the reflected light; the dichroic mirror and the scanning galvanometer are sequentially positioned on the optical path of the transmitted light; the transmitted light, after passing through the scanning galvanometer, is incident on the processing plane and reflected by the processing plane to form processing feedback light; the processing feedback light, after passing through the scanning galvanometer, is incident on the dichroic mirror and reflected by the dichroic mirror to form processing reflected light; the molten pool information monitoring device is positioned on the optical path of the processing reflected light; the controller is connected to the laser, the laser information monitoring device, the molten pool information monitoring device, and the scanning galvanometer. This invention uses a beam splitter to separate a portion of the forming laser emitted from the laser for laser power acquisition, and a dichroic mirror to separate a portion of the molten pool radiation beam for molten pool information acquisition, all achieved through a coaxial optical path. By processing the information from the laser power acquisition unit and the molten pool information acquisition unit, the controller can dynamically adjust the laser power, spot size, scanning speed, and scanning path based on the molten pool information. This enables dynamic and precise closed-loop control of the laser output power, providing basic information for energy control under different working conditions, further expanding the process scenarios, and improving forming quality. Attached Figure Description

[0015] Figure 1 This is a simplified structural diagram of the beam monitoring device used in Embodiment 1 of this utility model;

[0016] Figure 2 This is a simplified structural diagram of the beam monitoring device used in Embodiment 2 of this utility model;

[0017] Figure 3 This is a simplified structural diagram of the beam monitoring device used in Embodiment 3 of this utility model;

[0018] Figure 4 This is a simplified structural diagram of the beam monitoring device used in Embodiment 4 of this utility model;

[0019] Figure 5 This is the flowchart used in Embodiment 5 of this utility model;

[0020] Figure 6 This is the flowchart used in Embodiment 6 of this utility model;

[0021] Figure 7 This is the flowchart used in Embodiment 7 of this utility model;

[0022] Figure 8 This is the flowchart used in Embodiment 8 of this utility model;

[0023] in:

[0024] 1-Laser; 2-Beam expander; 3-Beam splitter; 4-Dynamic focusing lens; 5-Dichroic mirror; 6-Scanning galvanometer; 7-Attenuator; 8-Laser power acquisition unit; 9-Focusing lens; 10-Molten pool information acquisition unit; 11-Controller; 12-Processing plane; 13-Field lens; 14-Laser information acquisition unit. Detailed Implementation

[0025] This invention provides a beam monitoring device, including a controller 11, a laser 1, a beam splitter 3, a dichroic mirror 5, a scanning galvanometer 6, a laser information monitoring device, and a molten pool information monitoring device. The laser 1 emits a forming laser; the beam splitter 3 divides the forming laser into transmitted light and reflected light; the laser information monitoring device is disposed on the optical path of the reflected light; the dichroic mirror 5 and the scanning galvanometer 6 are disposed sequentially from front to back on the optical path of the transmitted light; the transmitted light after passing through the scanning galvanometer 6 is incident on the processing plane 12 and reflected by the processing plane 12 to form processing feedback light; the processing feedback light after passing through the scanning galvanometer 6 is incident on the dichroic mirror 5 and reflected by the dichroic mirror 5 to form processing reflected light; the molten pool information monitoring device is disposed on the optical path of the processing reflected light; the controller 11 is connected to the laser 1, the laser information monitoring device, the molten pool information monitoring device, and the scanning galvanometer 6.

[0026] The laser information monitoring device includes an attenuator 7 and a laser status acquisition unit arranged sequentially from front to back along the optical path of the reflected light; the controller 11 is connected to the laser status acquisition unit. For example, the laser status acquisition unit is either a laser power acquisition unit 8 or a laser information acquisition unit 14. The molten pool information monitoring device includes a focusing mirror 9 and a molten pool information acquisition unit 10 arranged sequentially from front to back along the optical path of the processed reflected light; the controller 11 is connected to the molten pool information acquisition unit 10. For example, when the laser power acquisition unit 8 detects that the power value deviates from the theoretical value by ≥0.5%, it adjusts the output power setting of the laser 1 to keep the deviation between the output power of the laser 1 and the theoretical value within <0.5% of the theoretical value. When the molten pool information acquisition unit 10 detects that the molten pool temperature deviates from the theoretical value by ≥1%, it adjusts the output power setting of the laser 1 to keep the deviation between the molten pool temperature and the theoretical value within <1% of the theoretical value; or it changes the original spot size by controlling the movement of the dynamic focusing mirror 9; or it changes the original scanning strategy by controlling the movement of the scanning galvanometer 6.

[0027] The beam monitoring device provided by this utility model also includes an optical focusing element placed between the beam splitter 3 and the dichroic mirror 5, or between the scanning galvanometer 6 and the processing plane 12. For example, when the optical focusing element is placed between the beam splitter 3 and the dichroic mirror 5, the optical focusing element is a dynamic focusing mirror 4; the beam splitter 3, the dynamic focusing mirror 4, the dichroic mirror 5, and the scanning galvanometer 6 are arranged sequentially from front to back along the optical path of the transmitted light; the controller 11 is connected to the dynamic focusing mirror 4. For example, when the optical focusing element is placed between the scanning galvanometer 6 and the processing plane 12, the optical focusing element is a field lens 13.

[0028] The beam monitoring device also includes a beam expander 2; the beam expander 2 and the beam splitter 3 are arranged sequentially from front to back on the optical path where the forming laser is located.

[0029] It should be noted that the controller 11 can communicate bidirectionally in real time with the laser 1, laser power acquisition unit 8, dynamic focusing mirror 9, molten pool information acquisition unit 10, and scanning galvanometer 6. The controller 11 processes the information from the laser power acquisition unit 8 and the molten pool information acquisition unit 10 to control the output power of the laser 1 and the movement of the dynamic focusing mirror 9 and the scanning galvanometer 6, thereby expanding the process scenarios and improving the forming quality.

[0030] The beam monitoring device provided by this utility model will now be described in detail with reference to the accompanying drawings:

[0031] Example 1:

[0032] See Figure 1The beam monitoring device mainly consists of a laser 1, a beam expander 2, a beam splitter 3, an attenuator 7, a laser power acquisition unit 8, a dynamic focusing mirror 4, a dichroic mirror 5, a focusing mirror 9, a molten pool information acquisition unit 10, and a scanning galvanometer 6. The beam splitter 3 and the optical axis of the forming laser form a 45° angle; the dichroic mirror 5 and the optical axis of the forming laser also form a 45° angle. For example, the beam splitter 3 has a transmittance ≥99% and a reflectance ≤1% for wavelengths from 1030nm to 1090nm; the dichroic mirror 5 has a transmittance ≥95% for wavelengths from 1030nm to 1090nm and a reflectance ≥95% for wavelengths from 1200nm to 2400nm.

[0033] See also Figure 1 In operation, the beam monitoring device first transmits the forming laser output from laser 1 through beam expander 2 to beam splitter 3. Most of the forming laser passes through beam splitter 3, while a small portion is reflected by beam splitter 3 to attenuator 7. After passing through attenuator 7, the beam reaches laser power acquisition unit 8, which collects the laser power. The beam passing through beam splitter 3 passes through dynamic focusing mirror 4 and dichroic mirror 5, and further reaches scanning galvanometer 6, forming a focused spot on processing plane 12. The focused spot interacts with the powder to form a molten pool, which radiates light outward. The light propagating through scanning galvanometer 6 to dichroic mirror 5, at wavelengths that meet the reflection conditions, is reflected to focusing mirror 9, focused, and then propagates to molten pool information acquisition unit 10, thus collecting molten pool information.

[0034] Example 2:

[0035] See Figure 2 The beam monitoring device differs from that in Embodiment 1 in that it lacks a dynamic focusing mirror 4, but adds a field mirror 13 after the scanning galvanometer 6. Its operation is as follows: First, the forming laser output from the laser 1 passes through the beam expander 2 and reaches the beam splitter 3. Most of the forming laser passes through the beam splitter 3, while a small portion is reflected by the beam splitter 3 to the attenuator 7. After passing through the attenuator 7, the beam reaches the laser power acquisition unit 8, which collects the laser power. The beam passing through the beam splitter 3 passes through the dichroic mirror 5 and the scanning galvanometer 6. The beam passing through the scanning galvanometer 6 passes through the field mirror 13 and forms a focused spot on the processing plane 12. The focused spot interacts with the powder to form a molten pool, which radiates light outward. The light propagating from the scanning galvanometer 6 to the dichroic mirror 5, at wavelengths that meet the reflection conditions, is reflected to the focusing mirror 9, focused, and then propagates to the molten pool information acquisition unit 10, thus collecting molten pool information. It can be seen that this operation is basically the same as that in Embodiment 1.

[0036] Example 3:

[0037] See Figure 3 This beam monitoring device is an extension of Embodiment 2. That is, it includes two sets of monitoring devices as shown in Embodiment 2, but is ultimately controlled by a single controller 11. See also... Figure 3 It includes a first set of beam monitoring devices A (hereinafter referred to as monitoring A) placed on the left side of the processing plane 12 and a second set of beam monitoring devices B (hereinafter referred to as monitoring B) placed on the right side of the processing plane 12. Monitoring A and monitoring B have the same structure and are arranged radially. They can be controlled separately or simultaneously by the controller 11, which can effectively improve processing efficiency.

[0038] Example 4:

[0039] See Figure 4 The beam monitoring device has the same structure as that shown in Embodiment 2. The difference is that in this embodiment, the laser power acquisition unit 8 is replaced with a laser information acquisition unit 14. The laser information acquisition unit 14 can acquire various parameters of the output beam of the laser 1, such as wavelength and beam quality. Its working process is the same as that of Embodiment 2, and will not be described again here.

[0040] The working principle of the beam monitoring device provided by this utility model is as follows:

[0041] 1) Construct the beam monitoring device as described above;

[0042] 2) Turn on laser 1 and emit a forming laser according to the current forming process requirements;

[0043] 3) The power of the forming laser is collected using a laser information monitoring device;

[0044] 4) Determine whether the power of the forming laser meets the current forming process requirements. If yes, proceed to step 5) based on the power of the forming laser collected in step 3). If no, adjust the power of the forming laser of laser 1 through controller 11 until the power of the forming laser collected in step 3) meets the current forming process requirements, and then proceed to step 5).

[0045] For example, step 4) is implemented as follows:

[0046] If |P 实际 -P 设置 If |<e1, then the power of the forming laser collected in step 3) will be used for step 5);

[0047] If |P 实际 -P 设置 If |≥e1, then the power of the forming laser of the laser 1 is adjusted by the controller 11 until the power of the forming laser collected in step 3) meets the current forming process requirements and then step 5) is performed.

[0048] Among them, P 实际 It is the power value of the shaping laser acquired in step 3); P 设置 It is the laser power setting value required by the current forming process in step 2); e1 is the power deviation threshold; preferably, e1 = P 设置 ×0.2%;

[0049] 5) Turn on the scanning galvanometer 6 and scan within the machining plane 12, and collect the molten pool temperature through the molten pool information monitoring device;

[0050] 6) Determine whether the molten pool temperature meets the requirements of the current forming process. If yes, continue the current forming process until forming is complete; otherwise, adjust the current forming process through controller 11 and form an updated forming process until forming is complete.

[0051] For example, step 6) is implemented as follows:

[0052] If |T 实际 -T 设置 If | < e2, continue the current forming process until forming is complete;

[0053] If |T 实际 -T 设置 If |≥e2, then the controller 11 will adjust the current forming process and form an updated forming process until the forming is completed.

[0054] Among them, T 实际 It is the molten pool temperature collected in step 5); T 设置 e2 is the melt pool temperature required by the current forming process in step 2); e2 is the melt pool temperature deviation threshold; preferably, e2 = T 设置 ×2%;

[0055] Preferably, in step 6), the specific way to regulate the current forming process and form the updated forming process by the controller 11 is method A, method B, method C or method D;

[0056] Method A: The power of the forming laser of the laser 1 is adjusted by the controller 11 to form an updated forming process;

[0057] Method B: Obtain the scanning speed of the scanning galvanometer 6, adjust the scanning speed of the scanning galvanometer 6 through the controller 11, and form an updated forming process;

[0058] Method C: Obtain the scanning path of the scanning galvanometer 6, adjust the scanning path of the scanning galvanometer 6 through the controller 11, and form an updated forming process;

[0059] Method D: Obtain the scanning speed and scanning path of the scanning galvanometer 6, and adjust the power of the forming laser based on the scanning speed and scanning path and the controller 11 to form an updated forming process.

[0060] The working principle of the beam monitoring device provided by this utility model will be described in detail below with reference to the accompanying drawings:

[0061] Example 5

[0062] See Figure 5 During the forming process, laser 1 emits light according to the laser power setting value required by the current process; the laser power acquisition unit 8 acquires the beam power value output by laser 1; subsequently, |P| is calculated. 实际 -P 设置 |。If|P 实际 -P 设置 If |≥e1, then the optical power is recalculated and returned, and the power of the shaping laser of laser 1 is adjusted by controller 11 until |P 实 The actual - P setting | < e1, where e1 is the power deviation threshold, for example, e1 is 0.2% of the laser power setting value; when |P actual - P setting| < e1, the scanning galvanometer 6 is activated to perform scanning motion, and then the molten pool temperature is collected by the molten pool information acquisition unit 10. At this time, |T is calculated. 实际 -T 设置 |, if |T 实际 -T 设置 If |≥e2, then the optical power is recalculated, and the power of the shaping laser of laser 1 is adjusted by controller 11 until |T 实际 -T 设置 |<e2 and form an updated forming process, where e2 is the melt pool temperature deviation threshold. For example, in this embodiment, e2 is T 设置 2%; when |T 实际 -T 设置 If | < e2, then continue forming using the current forming process.

[0063] Example 6:

[0064] See Figure 6 During the forming process, laser 1 emits light according to the laser power setting value required by the current process; the laser power acquisition unit 8 acquires the beam power value output by laser 1; subsequently, |P| is calculated. 实际 -P 设置 |。If|P 实际 -P 设置 If |≥e1, then the optical power is recalculated and returned, and the power of the shaping laser of laser 1 is adjusted by controller 11 until |P 实The actual - P setting | < e1, where e1 is the power deviation threshold, for example, e1 is 0.2% of the laser power setting value; when |P actual - P setting| < e1, the scanning galvanometer 6 is activated to perform scanning motion, and then the molten pool temperature is collected by the molten pool information acquisition unit 10. At this time, |T is calculated. 实际 -T 设置 |, if |T 实际 -T 设置 If |≥e2, then the scanning speed of the scanning galvanometer 6 is recalculated, and the scanning speed of the scanning galvanometer 6 is adjusted by the controller 11 until |T 实际 -T 设置 |<e2 and form an updated forming process, where e2 is the melt pool temperature deviation threshold. For example, in this embodiment, e2 is T 设置 2%; when |T 实际 -T 设置 If | < e2, then continue forming using the current forming process.

[0065] Example 7

[0066] See Figure 7 The working process of this embodiment is basically the same as that of embodiment 6, except that the calculation of |T 实际 -T 设置 If |T_actual - T_set| ≥ e2, then the scanning path of the scanning galvanometer 6 is recalculated, and the scanning path of the scanning galvanometer 6 is adjusted by the controller 11 until |T_actual - T_set| ≥ e2. 实际 -T 设置 |<e2 and form an updated forming process. The other processes are exactly the same as in Example 6, and will not be described again here.

[0067] Example 8

[0068] See Figure 8 The difference between this embodiment and the previous embodiments is that in calculating |T 实际 -T 设置 |After that, if|T 实际 -T 设置 If |≥e2, then the scanning speed and scanning path of the scanning galvanometer 6 are obtained. Based on the scanning speed and scanning path, the power of the forming laser is adjusted by the controller 11 to form an updated forming process. The other processes are exactly the same as in Example 6, and will not be described again here.

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