Printing height monitoring device
By designing a printing height monitoring device including a camera and a motion mechanism in laser directional energy deposition 3D printing, the problem of inconvenient installation of sensors in the molten pool area is solved, accurate measurement and real-time monitoring of printing height are achieved, and printing quality is significantly improved.
Patent Information
- Application Number
- CN202421516765.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-29
- Publication Date
- 2025-05-06
- Estimated Expiration
- 2034-06-29
AI Technical Summary
During the 3D printing process of high-power laser directional energy deposition, the complex environment in the molten pool area leads to inconvenient installation of sensors and the inability to accurately measure the printing height, which in turn affects the forming quality.
A printing height monitoring device is designed, including a camera, a first moving mechanism and a reference object disposed on the laser generator. The camera is lifted and rotated by the first moving mechanism to monitor the distance between the reference object and the forming surface in real time, so as to achieve accurate measurement of the printing height.
The device can monitor the printing height in real time in the complex environment of the molten pool area, quickly judge and early warning of the printing height and forming quality, significantly improving the printing quality.
Smart Images
Figure CN222830729U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of additive manufacturing and relates to a printing height monitoring device, in particular to a directional energy deposition real-time printing height monitoring device. Background Art
[0002] Directed energy deposition is a process in which a laser or other energy source generates a molten pool in the deposition area and moves it at high speed. The material is directly fed into the high-temperature melting zone in the form of powder or filament, and deposited layer by layer after melting. This is called laser directed energy deposition 3D printing technology. The high stability of the work in real time during laser directed energy deposition printing is a direct proof of the stability of the reaction printing process. However, during the laser directed energy deposition process, it is necessary to ensure that the light spot, powder spot and the part processing surface coincide in height. When the part processing surface is above the powder spot, the part's printing layer thickness will be reduced and the part's features will be lost; when the part processing surface is below the powder spot, the energy absorbed by the substrate is too low, resulting in metallurgical defects such as poor fusion.
[0003] Moreover, in the process of high-power laser directional energy deposition, the laser power is usually above 6000W, and the temperature of the molten pool (iron-based / titanium-based / nickel-based) reaches above 1400℃, of which the energy absorbed by the molten pool is usually less than 50%, so the molten pool area is a high-temperature area with severe laser reflection. At the same time, based on the technical principle of coaxial powder feeding, there is also powder in the molten pool area, and the strong interaction between the airflow and the laser produces other phenomena: such as metal vapor, plasma, etc. These factors make the installation of the sensor inconvenient, and the sensor cannot overcome the damage caused by laser reflection radiation and high temperature; at the same time, the complex heat, light, and airflow environment in the molten pool area make it impossible to accurately guarantee the measurement results.
[0004] Therefore, in high-power laser directed energy deposition printing, it is difficult to install effective acoustic, optical, electrical and other sensors in the molten pool area to measure the height in real time during printing, and thus the forming quality cannot be ensured. Utility Model Content
[0005] In order to solve the above technical problems existing in the background technology, the utility model provides a printing height monitoring device which is convenient for obtaining the printing height and can effectively improve the printing quality.
[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0007] A printing height monitoring device, characterized in that: the printing height monitoring device includes a camera, a first motion mechanism and a reference object arranged on a laser generator; the first motion mechanism is connected to the camera and drives the camera to rise and fall and rotate; the camera monitors the distance from the reference object to the forming surface.
[0008] The reference object is a self-luminous reference object or a light-reflecting reference object.
[0009] When the reference object is a self-luminous reference object, the reference object is a light source, and the light source is one group or multiple groups; when the light source is multiple groups, the multiple groups of light sources are on the same horizontal plane.
[0010] When the above-mentioned reference object is a reflective reference object for light, the reference object is a light reflecting element, and the light reflecting element is a single element or a disconnected linear structure or a complete linear structure spliced by multiple single elements; the printing height monitoring device also includes a reference light source; the light reflecting element is placed on the optical path where the reference light source is located.
[0011] The printing height monitoring device further comprises a laser filter arranged on the camera lens side.
[0012] The above-mentioned first motion mechanism includes a lifting device and a rotating device placed on the top of the lifting device; the camera is placed on the rotating device; the lifting device drives the rotating device and the camera to rise and fall freely along the axial direction of the lifting device; the rotating device drives the camera to rotate freely around the axial direction of the lifting device.
[0013] The printing height monitoring device also includes an industrial computer connected to the first motion mechanism and the camera.
[0014] The printing height monitoring device also includes a position encoder arranged on the laser generator and connected to the industrial computer.
[0015] The printing height monitoring device also includes a second motion mechanism connected to the laser generator; the second motion mechanism is an XYZ three-axis motion platform.
[0016] The printing height monitoring device also includes an alarm connected to the industrial computer.
[0017] The advantages of the utility model are:
[0018] The utility model provides a printing height monitoring device, including a camera, a first motion mechanism, and a reference object arranged on a laser generator; the first motion mechanism is connected to the camera and drives the camera to rise and fall and rotate; the camera monitors the distance from the reference object to the forming surface. The printing height monitoring device provided by the utility model can monitor the actual printing height (i.e., the distance between the reference object and the forming surface) in real time in a complex environment of a molten pool area, and can also quickly judge or even warn the printing height and forming quality, and has good market promotion value. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic diagram of the structure of the printing height monitoring device provided by the utility model;
[0020] Figure 2 It is a schematic diagram of laser printing;
[0021] Figure 3 This is a monitoring principle diagram of the printing height monitoring device provided by the utility model;
[0022] in:
[0023] 1-industrial computer; 2-alarm; 3-first motion mechanism; 4-camera; 5-laser filter; 6-position encoder; 7-second motion mechanism; 8-laser generator; 81-forming laser; 9-reference object; 10-forming surface. DETAILED DESCRIPTION
[0024] See also Figure 1 The utility model provides a printing height monitoring device, including a camera 4, a first motion mechanism 3, and a reference object 9 arranged on a laser generator 8; the first motion mechanism 3 is connected to the camera 4 and drives the camera 4 to rise and fall and rotate; the camera 4 monitors the distance from the reference object 9 to the forming surface 10. It can be understood that the height of the camera 4 and the distance from the laser generator 8 are not limited in this solution, as long as the camera 4 can capture the reference object 9 and the forming surface 10.
[0025] Among them, the camera 4 can be a monocular camera, a multi-camera camera or other forms of cameras, which is not limited in this application. In some embodiments, the camera can also perform automatic focusing. Specifically, the print height detection device can obtain the distance between the camera and the photographed object (for example, the distance between the camera and the laser generator), and call the appropriate focusing parameters based on the distance to achieve automatic focusing, thereby ensuring the accuracy of the image information. Compared with the traditional method of automatically focusing the camera based on the clarity of the current photo, since the camera automatic focusing solution provided in this application calls the appropriate focusing parameters based on the actual distance between the camera and the photographed object, the focusing is faster and more accurate, and the image quality obtained is higher.
[0026] The working principle of the utility model is: in the normal additive manufacturing process, the distance between the laser generator 8 and the forming surface 10 is relatively constant, and even a small amount of fluctuation is within the allowable range, that is, the light spot, powder spot and the part processing surface overlap in height during the laser directional energy deposition process. However, when the part processing surface is above or below the powder spot, the light spot, powder spot and the part processing surface do not overlap in height according to the design requirements. At this time, the distance between the laser generator 8 and the forming surface 10 will change. Since the reference object 9 is fixedly set on the laser generator 8, the distance from the forming surface 10, especially the powder spot, will change. At this time, the distance between the reference object 9 and the forming surface 10 is monitored in real time by the camera 4, so that the printing height and forming quality can be quickly judged or even warned.
[0027] Exemplarily, the camera 4 used in the present invention may be a high-resolution monocular autofocus camera.
[0028] The reference object 9 is a self-luminous reference object or a light-reflecting reference object.
[0029] When the reference object 9 is a self-luminous reference object, the reference object 9 is a light source, and the light source is one or more groups; when the light source is multiple groups, the multiple groups of light sources are on the same horizontal plane. Figure 2 The light sources are LED lamp A and LED lamp B. The two LEDs are on the same horizontal plane and can also serve as reference objects. Usually, the LED lamp is set at the lower end of the laser generator 8. The distance from the printing point on the forming surface to the plane where the two LEDs are located can be considered as the printing height. For example, the distance between LED lamp A and LED lamp B is about 3mm, and the lumens of LED lamp A and LED lamp B are about 3000LM. The brightness design value of the light source is close to the brightness of the molten pool.
[0030] When the reference object 9 is a light-reflecting reference object, the reference object 9 is a light-reflecting element, which is a single element or a disconnected linear structure or a complete linear structure formed by splicing multiple single elements; the printing height monitoring device also includes a reference light source; the light-reflecting element is placed on the light path where the reference light source is located. Exemplarily, the light-reflecting element is a reflector or a reflective strip.
[0031] The printing height monitoring device further includes a laser filter 5 arranged on the lens side of the camera 4 .
[0032] The first motion mechanism 3 used in the utility model includes a lifting device and a rotating device placed on the top of the lifting device; the camera 4 is placed on the rotating device; the lifting device drives the rotating device and the camera 4 to freely lift and lower along the axial direction of the lifting device; the rotating device drives the camera 4 to freely rotate around the axial direction of the lifting device. The lifting is to ensure that the camera 4 is at a suitable height, for example, the camera 4 is at the same height or a similar height as the laser generator 8 to be monitored, so as to avoid errors in the monitoring results caused by deviations in the pitch angle; the rotation is to ensure that when the laser generator 8 moves in the XY direction on the forming surface 10, the camera 4 can be prompted to promptly follow the different positions of the laser generator 8.
[0033] The printing height monitoring device further includes an industrial computer 1 connected to the first motion mechanism 3 and the camera 4. Exemplarily, the industrial computer 1 can be simplified to a programmable logic controller PLC.
[0034] The printing height monitoring device also includes a position encoder 6 arranged on the laser generator 8 and connected to the industrial computer 1. The position encoder 6 can record the position coordinates of the laser generator 8 on the forming surface 10 and transmit the position coordinates to the industrial computer 1, so that the industrial computer can make height reference comparison and real-time height monitoring based on the same position coordinates.
[0035] The printing height monitoring device also includes a second motion mechanism 7 connected to the laser generator 8; the second motion mechanism 7 is an XYZ three-axis motion platform, which can drive the laser generator 8 to move in the X and Y directions on the forming surface 10 through the second motion mechanism 7, and at the same time, the laser generator 8 can be lifted along the Z direction to complete the lifting of the laser generator 8.
[0036] The printing height monitoring device also includes an alarm 2 connected to the industrial computer 1 for giving an alarm for abnormal height.
[0037] See also Figure 2 as well as Figure 3 When the printing height monitoring device provided by the utility model is working, the laser generator 8 will move to the preset position and turn on the laser generator 8 through the camera. The forming laser 81 falls on the forming surface 10 and performs printing according to the forming instruction. At this time, the forming laser 81 will generate a light spot at the printing point on the forming surface 10. The reference object 9 on the laser generator 8, such as LED light A and LED light B, is in the turned-on state. By taking pictures of the laser generator 8 and the forming surface 10 through the camera 4, an image including three bright spots of LED light A, LED light B and the printing point on the forming surface can be obtained. By processing the image, the scaling factor k can be obtained based on the actual distance between LED light A and LED light B and the image distance of the two light spots corresponding to LED light A and LED light B in the image. Combined with the vertical distance from the printing point in the image to the straight line formed by the two light spots corresponding to LED light A and LED light B, the actual printing height can be obtained. With the movement of the second motion mechanism 7, the actual printing height of each printing point on the forming surface 10 can be measured.
[0038] See also Figure 3, assuming that point C is the theoretical printing height of the printing point at the preset position, the actual printing height may be higher or lower during actual measurement, such as point C1 and point C2 in the figure. At this time, the camera compares C (theoretical forming distance) at the same position with C1 or C2 (C1 is the real-time monitoring upper defocus position, and C2 is the real-time monitoring lower defocus position). Taking C1 as an example, if the distance between C1 and C is within the allowable fluctuation range D1 (theoretical design threshold, exemplary, the setting of the threshold can be divided into zones according to the relationship between the part coordinates and the device coordinates. When the part size is small, the outline size is <500mm, usually the threshold The value is set to a fixed value; when the part size is large, the outline size is ≥500mm, especially for some large-sized parts, there is a certain deformation during printing. The threshold is set reasonably according to the deformation direction of the part to ensure the continuity of printing), that is, |C1-C|≤D1, then the printing height is reasonable, which is the height required by the design, and the forming quality can be achieved; if the distance between C1 and C exceeds the allowable fluctuation range D1, that is, |C1-C|>D1, then the printing height is abnormal, that is, the forming height is higher than the theoretical forming height, the energy absorbed by the substrate is too low, and metallurgical defects such as poor fusion will occur. At this time, an alarm 2 is used for warning. Similarly, if the distance between C2 and C is within the allowable fluctuation range D2, that is, |C2-C|≤D1, then the printing height is reasonable, which is the height required by the design, and the forming quality can be achieved; if the distance between C2 and C exceeds the allowable fluctuation range D1, that is, |C2-C|>D1, then the printing height is abnormal, that is, the forming height is significantly lower than the theoretical forming height, the printing layer thickness of the part will be reduced, and the characteristics of the part will be lost. At this time, an alarm 2 is used for warning. When the height monitoring of the current printing layer is completed, the laser generator 8 is driven by the industrial computer 1 and the second motion mechanism 7 to move up one printing layer, and the industrial computer 1 and the first motion mechanism 3 are synchronously moved up one printing layer, that is, the lifting amount of the second motion mechanism 7 is the same as the lifting amount of the first motion mechanism 3. In this case, the above method is repeated to complete the height monitoring of the layer.
Claims
1. A printing height monitoring device, characterized in that: The printing height monitoring device comprises a camera (4), a first motion mechanism (3), and a reference object (9) arranged on a laser generator (8); the first motion mechanism (3) is connected to the camera (4) and drives the camera (4) to rise, fall and rotate; the camera (4) monitors the distance from the reference object (9) to the forming surface (10).
2. The printing height monitoring device according to claim 1, characterized in that: The reference object (9) is a self-luminous reference object or a light-reflecting reference object.
3. The printing height monitoring device according to claim 2, characterized in that: When the reference object (9) is a self-luminous reference object, the reference object (9) is a light source, and the light source is one group or multiple groups; when the light source is multiple groups, the multiple groups of light sources are on the same horizontal plane.
4. The printing height monitoring device according to claim 2, characterized in that: When the reference object (9) is a light-reflecting reference object, the reference object (9) is a light-reflecting element, and the light-reflecting element is a single element or a disconnected linear structure or a complete linear structure formed by splicing a plurality of single elements; the printing height monitoring device also includes a reference light source; and the light-reflecting element is placed on the light path where the reference light source is located.
5. The printing height monitoring device according to claim 1, 2, 3 or 4, characterized in that: The printing height monitoring device also includes a laser filter (5) arranged on the lens side of the camera (4).
6. The printing height monitoring device according to claim 5, characterized in that: The first motion mechanism (3) comprises a lifting device and a rotating device placed on the top of the lifting device; the camera (4) is placed on the rotating device; the lifting device drives the rotating device and the camera (4) to be lifted and lowered freely along the axial direction of the lifting device; the rotating device drives the camera (4) to be rotated freely around the axial direction of the lifting device.
7. The printing height monitoring device according to claim 6, characterized in that: The printing height monitoring device also includes an industrial computer (1) connected to the first motion mechanism (3) and the camera (4).
8. The printing height monitoring device according to claim 7, characterized in that: The printing height monitoring device also includes a position encoder (6) arranged on the laser generator (8) and connected to the industrial computer (1).
9. The printing height monitoring device according to claim 8, characterized in that: The printing height monitoring device further comprises a second motion mechanism (7) connected to the laser generator (8); the second motion mechanism (7) is an XYZ three-axis motion platform.
10. The printing height monitoring device according to claim 9, characterized in that: The printing height monitoring device also includes an alarm (2) connected to the industrial computer (1).