Powder laying monitoring grafting method of metal 3D printing equipment

Abstract

The invention relates to a metal 3D printing equipment powder laying monitoring grafting method which comprises the following steps: S1, after galvanometer scanning precision calibration, laser scans calibrated N * N points on a substrate on a working plane; acquiring an image by an industrial camera to obtain pixel coordinates (Qx [i], Qy [i]) of the N * N point in the image; s2, obtaining N * N point coordinates (Dx [i], Dy [i]) of the substrate under a galvanometer scanning coordinate system through a high-precision quadratic element measuring instrument, and establishing a mapping relation between pixel coordinates and galvanometer scanning coordinates; s3, mounting a base part, acquiring images by an industrial camera to obtain pixel coordinates of the base part, and converting from the position of a galvanometer scanning coordinate system to the position of a pixel coordinate system; s4, acquiring a current printing layer slice file and analyzing contour information; and S5, mapping the slice data coordinates to the part pixel coordinates in the image to realize automatic alignment of the part in the slice file to the substrate part. According to the invention, high-precision rapid grafting is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of additive manufacturing, and in particular relates to a powder spreading monitoring and grafting method for metal 3D printing equipment. Background Art

[0002] Additive manufacturing (also known as laser selective melting or metal 3D printing) technology is a new processing method that has emerged in recent years. The raw materials used in this technology are all powders of tens to hundreds of microns. During the forming process, the powder is evenly spread on the forming substrate through the powder supply mechanism and the powder spreading mechanism, and then the powder in the specific geometric shape area of ​​the surface is melted by energy sources such as laser to produce metallurgical bonding, and finally the parts are grown layer by layer to achieve the three-dimensional forming process.

[0003] At present, 3D printing is a manufacturing method that imports slice files into the equipment and controls the software to form layer by layer. The forming materials are mostly metals or plastics. With the rapid application of metal 3D printing technology in the mold industry, molds are given more reasonable and complex conformal cooling water channel solutions, aiming to increase the cooling rate of molded parts and improve production efficiency; and effectively reduce internal stress and reduce the defective rate of molded parts; to reduce costs, the mold conformal cooling water channel part is usually 3D printed on the mold insert base in a secondary forming manner. The accuracy of the secondary forming of the mold insert base and the conformal cooling water channel part affects the overall service life and cooling effect of the mold. In order to improve the accuracy of secondary forming, it is necessary to develop a grafting function based on the powder laying monitoring system of the metal 3D printing equipment.

[0004] There are many different grafting methods available, including:

[0005] 1. Use a special insert matrix installation method to fix the matrix forming position, pre-sinter each time, observe the deviation, manually move the part position in the slice file, and repeat sintering until it reaches the visual accuracy level;

[0006] 2. Use an industrial camera to capture images, identify the installation position of the substrate, parse its position information through software, move it corresponding to the vector information in the slice file, observe the deviation after pre-sintering, manually move the part position in the slice, and repeat sintering until it reaches the level of visual accuracy.

[0007] In the grafting work, the main issues involved are speed and accuracy. However, in the above grafting work, the actual installation position and angle of the substrate are difficult to measure and cannot be determined; and the laser sintering position cannot correspond to the installation position of the substrate. Even if an industrial camera is used to collect images, identify the substrate position information, and then move the part position in the slice, the actual sintering position is still determined by pre-sintering, which lacks a calibration system and self-compensation, resulting in slow speed and poor accuracy. Summary of the invention

[0008] In order to overcome the problems of slow grafting speed and poor grafting accuracy in the grafting printing process of existing metal 3D printing equipment, which leads to part printing failure, the present invention proposes a powder spreading monitoring grafting method for metal 3D printing equipment, which can not only detect the powder spreading status and the part status after scanning in real time, but also automatically determine whether there are defects through image algorithm software. When defects exist, it automatically determines the defect type and level, marks the defect area, and takes corresponding disposal actions. It can also achieve high-precision and rapid grafting, thereby improving the success rate of metal 3D printed parts.

[0009] The present invention is implemented as follows: a metal 3D printing equipment powder spreading monitoring grafting method, the grafting method is implemented by a monitoring system, and the monitoring system is installed in the upper computer system software of the printing equipment;

[0010] The grafting method comprises the following steps:

[0011] S1. The galvanometer is first calibrated in a routine manner. After the galvanometer scanning accuracy is calibrated, the laser scans the calibrated N*N points on the substrate on the working plane; after scanning, the industrial camera captures the image and obtains the pixel coordinates (Qx[i], Qy[i]) of these N*N points in the image;

[0012] S2. After the industrial camera is finished shooting, the substrate is measured by a high-precision two-dimensional measuring instrument to obtain the coordinates of the N*N points in the galvanometer scanning coordinate system (Dx[i], Dy[i]). The mapping relationship between the pixel coordinates in the pixel coordinate system and the galvanometer scanning coordinates in the galvanometer scanning coordinate system is established by the image algorithm software of the monitoring system, as follows:

[0013]

[0014] S3, install the base part, and then use the industrial camera to collect images to obtain the pixel coordinates of the base part. Through the above operator mapping relationship matrix, the galvanometer scanning coordinate system position is converted to the pixel coordinate system position, that is:

[0015]

[0016] S4, the monitoring system communicates with the host computer system of the printing device to obtain the current printing layer slice file and parse the contour information;

[0017] S5. The image algorithm software of the monitoring system maps the slice data coordinates to the pixel coordinates of the parts in the image through the above matrix, so as to automatically align the parts in the slice file to the substrate parts and realize automatic grafting.

[0018] In the above technical solution, preferably, the mapping relationship includes but is not limited to translation, rotation, and scaling.

[0019] The advantages and positive effects of the present invention are:

[0020] 1. The monitoring system used in the grafting method of the present invention can monitor and detect the powder spreading and laser sintering status of the printing equipment in real time only through the industrial camera installed outside the forming cabin and the image algorithm software installed on the computer. When defects occur, they can be quickly identified and accurately judged, and different response measures can be automatically taken; the monitoring system has a high-precision automatic grafting function, which can implement automatic grafting, automatically identify the position of the part base, match the slicing information, realize automatic grafting printing, improve work efficiency, and ensure accuracy; and the detection of the monitoring system provides a guarantee for the long-term stable printing of the equipment, thereby improving the success rate of part printing.

[0021] 2. The monitoring system used in the grafting method of the present invention can output the grafting deviation value of the parts, avoid the grafting failure caused by poor substrate processing accuracy, and realize deviation visualization; the degree of automation is high, and after the parts are installed, grafting can be performed with one click, which greatly reduces the workload of the staff and improves the success rate of part grafting.

[0022] 3. The monitoring system used in the grafting method of the present invention has low cost, simple operation and comprehensive functions; it has low computer requirements for the industrial camera and image algorithm software used, saving production costs; it is easy to install and has strong applicability, and is not affected by the size, material, parameters and other issues of the formed parts, and can be applied to different types of powder laying equipment; the industrial camera is installed outside the forming cabin to reduce the impact of powder, smoke, pressure and other problems in the cabin, thereby extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow chart of a grafting method provided by an embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of a monitoring system provided by an embodiment of the present invention.

[0025] In the figure: 1. Industrial camera; 2. Base parts; 3. Light source; 4. Computer; 5. Display. DETAILED DESCRIPTION

[0026] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0027] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] See also Figure 2 The forming chamber is illuminated by a light source 3 to ensure uniform and stable illumination at each position within the forming format. The position information of the base part 2 is captured by an industrial camera 1 and transmitted to the image algorithm software in a computer 4 for analysis and automatic calculation and movement of the slice data position. The calculation results are displayed on a display 5 and grafting begins.

[0030] See also Figure 1 An embodiment of the present invention provides a metal 3D printing device powder spreading monitoring grafting method, which is implemented by a monitoring system installed in the upper computer system software of the printing device.

[0031] The grafting method comprises the following steps:

[0032] S1. The galvanometer is first calibrated in a routine manner. After the galvanometer scanning accuracy is calibrated, the laser scans the calibrated N*N points on the substrate on the working plane; after scanning, the industrial camera captures the image and obtains the pixel coordinates (Qx[i], Qy[i]) of these N*N points in the image. In this embodiment, N*N points are 289 points.

[0033] S2. After the industrial camera is finished shooting, the substrate is measured by a high-precision two-dimensional measuring instrument to obtain the coordinates of the N*N points in the galvanometer scanning coordinate system (Dx[i], Dy[i]). The mapping relationship between the pixel coordinates in the pixel coordinate system and the galvanometer scanning coordinates in the galvanometer scanning coordinate system is established by the image algorithm software of the monitoring system, as follows:

[0034]

[0035] S3, install the base part, and then use the industrial camera to collect images to obtain the pixel coordinates of the base part. Through the above operator mapping relationship matrix, the galvanometer scanning coordinate system position is converted to the pixel coordinate system position, that is:

[0036]

[0037] The mapping relationship includes but is not limited to translation, rotation, and scaling.

[0038] S4. The monitoring system communicates with the upper computer system of the printing device to obtain the current printing layer slice file and parse the contour information.

[0039] S5. The image algorithm software of the monitoring system maps the slice data coordinates to the pixel coordinates of the parts in the image through the above matrix, so as to automatically align the parts in the slice file to the substrate parts and realize automatic grafting.

[0040] During grafting, the laser and industrial camera are calibrated to scan the position on the working plane, the base parts to be grafted are installed, the industrial camera collects images to identify the base position information, and the slice data is introduced. The image algorithm software processes the slice data through a matrix to realize automatic translation and rotation of the parts in the slice file, and the grafting speed is fast and the precision is high.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for monitoring and grafting powder for metal 3D printing equipment, characterized in that: The grafting method is implemented by a monitoring system, which is installed in the upper computer system software of the printing device; The grafting method comprises the following steps: S1. The galvanometer is first calibrated in a routine manner. After the galvanometer scanning accuracy is calibrated, the laser scans the calibrated N*N points on the substrate on the working plane; after scanning, the industrial camera captures the image and obtains the pixel coordinates (Qx[i], Qy[i]) of these N*N points in the image; S2. After the industrial camera is finished shooting, the substrate is measured by a high-precision two-dimensional measuring instrument to obtain the coordinates of the N*N points in the galvanometer scanning coordinate system (Dx[i], Dy[i]). The mapping relationship between the pixel coordinates in the pixel coordinate system and the galvanometer scanning coordinates in the galvanometer scanning coordinate system is established by the image algorithm software of the monitoring system, as follows: S3, install the base part, and then use the industrial camera to collect images to obtain the pixel coordinates of the base part. Through the above operator mapping relationship matrix, the galvanometer scanning coordinate system position is converted to the pixel coordinate system position, that is: S4, the monitoring system communicates with the host computer system of the printing device to obtain the current printing layer slice file and parse the contour information; S5. The image algorithm software of the monitoring system maps the slice data coordinates to the pixel coordinates of the parts in the image through the above matrix, so as to automatically align the parts in the slice file to the substrate parts and realize automatic grafting.

2. The method for monitoring and grafting powder for metal 3D printing equipment according to claim 1, characterized in that: The mapping relationship includes but is not limited to translation, rotation, and scaling.

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