CN110823758A - Observation device for powder density distribution and image processing and nozzle optimization method - Google Patents

Abstract

An observation device for powder density distribution and an image processing and nozzle optimization method are disclosed, the device comprises a main body support, the main body support is composed of a bottom plate and a stand column arranged on the bottom plate, a powder collecting box is arranged on the bottom plate, a powder feeding nozzle is arranged above the powder collecting box, powder is formed into powder beams through the powder feeding nozzle and is sprayed downwards, a camera is arranged above the powder feeding nozzle, the camera is connected with the tail end of the powder feeding nozzle through a lens arranged downwards and a telescopic shield, and the lens, the telescopic shield and the powder feeding nozzle are arranged on the same axis; a linear light source is arranged below the powder feeding nozzle, and the light emitting direction of the linear light source is vertical to the spraying direction of the powder beams; the powder feeding nozzle is connected with the stand column through the adapter, the adapter can adjust the height of the powder feeding nozzle, the distance between the line light source and the powder feeding nozzle is equal to the working distance of the laser processing head, and the light emitting surface of the line light source is a working surface. The invention has flexible adjustment and can clearly reflect the powder distribution density on a specific cross section after image processing.

Description

Observation device and image processing and nozzle optimization method for powder density distribution

technical field

The invention belongs to the field of additive manufacturing, and relates to an observation device for powder density distribution and a method for image processing and nozzle optimization.

Background technique

In the metal additive manufacturing industry, Laser Melting Deposition (LMD) technology has been paid more and more attention. The principle of LMD technology is that the powder feeder sends the metal powder to the nozzle of the laser processing head. After passing through the nozzle, the powder gathers on the working surface. The laser is focused on the working surface through the collimating lens and focusing lens to form a molten pool, and the metal powder is rapidly melted in the molten pool. metal layer.

The matching of the powder density distribution at the working face with the laser power density distribution has a huge impact on the forming quality and powder utilization. In order to improve the powder feeding nozzle, improve the matching degree of optical powder, and then improve the forming quality and powder utilization rate, it is necessary to measure the powder density distribution at the working surface. But there is currently no good solution to this problem.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an observation device, image processing and nozzle optimization method for powder density distribution in view of the problem that the prior art cannot effectively obtain the powder density distribution at the working surface during the metal additive manufacturing process.

In order to achieve the above object, the technical scheme adopted in the present invention is:

An observation device for powder density distribution includes a main body bracket, the main body bracket is composed of a bottom plate and a column mounted on the bottom plate, a powder collecting box is arranged on the bottom plate, a powder feeding nozzle is arranged above the powder collecting box, and the powder is formed into powder through the powder feeding nozzle. The beam is sprayed downward, and the powder collection box is used to collect the sprayed powder; a camera is set above the powder feeding nozzle, and the camera is connected to the tail end of the powder feeding nozzle through the telescopic shield through the lens set downward. The surrounding light enters the lens, and the lens, the telescopic shield and the powder feeding nozzle are arranged on the same axis; the camera, the lens, the telescopic shield and the powder feeding nozzle are installed through the column, and the lens below the powder feeding nozzle is installed. A line light source is set on the column, and the light emission direction of the line light source is perpendicular to the powder beam ejection direction; the powder feeding nozzle is connected to the column through an adapter, and the adapter can adjust the height of the powder feeding nozzle, so that the distance between the line light source and the powder feeding nozzle is equal to the laser processing. The working distance of the head, the light emitting surface of the line light source is the working surface.

Preferably, in an embodiment of the powder density distribution observation device of the present invention, the telescopic shield can expand and contract with the movement of the powder feeding nozzle, and the expansion and contraction range is greater than the up and down movement range of the adapter.

Preferably, in an embodiment of the powder density distribution observation device of the present invention, the telescopic shield is connected to the tail end of the powder feeding nozzle through an adapter, the upper end face of the adapter is connected to the telescopic shield, and the lower end face is connected to the powder feeding nozzle. The nozzle is connected, and a through hole that can be observed by the lens is processed between the upper and lower end faces.

Preferably, in an embodiment of the powder density distribution observation device of the present invention, the camera, the adapter and the line light source are connected to an industrial computer; the industrial computer is used to control the up and down movement of the adapter and control the emission of the line light source. Light, acquire the image captured by the camera and save and process it.

Preferably, in an embodiment of the powder density distribution observation device of the present invention, the power of the light emitted by the line light source is not less than 1 mW, the line width is not more than 5 mm, and the wavelength band of the line light source should be included in the response band of the camera. .

Preferably, in an embodiment of the device for observing powder density distribution of the present invention, the repeatability of the adapter is ≤0.5 mm.

The present invention also provides an image processing method for powder density distribution. Based on the observation device for powder density distribution, firstly, a camera is used to collect multiple photos, and the RBG values of the corresponding pixel points of the multiple photos are superimposed to obtain an average value. The average value is assigned to a new image; let the number of pixels in the new image be n, and then find the maximum value of R, the maximum value of G, and the maximum value of B in all the pixels, denoted as Rmax, Gmax, For Bmax, the proportional coefficients αr=255/Rmax, αg=255/Gmax, and αb=255/Bmax are obtained. Finally, the R of each pixel of the new image is multiplied by αr, the G of each pixel of the new image is multiplied by αg, and the B of each pixel of the new image is multiplied by αb to obtain the final processed image.

The present invention also provides a method for optimizing the design of a powder feeding nozzle. According to the image processing method for the powder density distribution, by adjusting the height of the powder feeding nozzle, the powder at other cross-sections other than the working surface of the laser processing head can be obtained. Density distribution, optimize the design of the powder feeding nozzle by synthesizing the powder distribution on the working face of the laser processing head and other upper and lower positions.

Compared with the prior art, the observation device for powder density distribution of the present invention has the following beneficial effects: the line light source emits light perpendicular to the spraying direction of the powder beam, the line light source illuminates the powder, and the camera is passed from above the powder feeding nozzle. The plane illuminated by the line light source is shot vertically downward along the ejection direction. Since the distance between the line light source and the powder feeding nozzle is equal to the working distance of the laser processing head, and the light emitting surface of the line light source is the working surface, the working surface of the laser processing head can be obtained. powder density distribution. The powder feeding nozzle of the present invention is connected with the upright column through an adapter, the up and down movement of the adapter on the main body can be realized by any linear motion system, and the height of the powder feeding nozzle can be adjusted conveniently through the adapter. The lens is connected to the rear end of the powder feeding nozzle through a telescopic shield, which can move up and down with the adapter and prevent surrounding light from entering the lens. The invention can accurately reflect the actual working conditions of the nozzles during processing by the laser processing head, and the adjustment is flexible, and the collected images are clear.

Compared with the prior art, in the image processing method of the present invention, the camera first collects multiple photos, and the final image is synthesized from multiple photos. On the image of the new image, by calculating the ratio of the maximum RBG and 255 in the RBG of each point on the new image, the RGB value of each pixel is multiplied by the above ratio value, so as to brighten the image and obtain the final picture, which clearly reflects the Powder density distribution at a specific cross-section.

Compared with the prior art, in the optimization design method of the powder feeding nozzle of the present invention, after the powder density distribution at the working surface is photographed, the powder density distribution at other cross-sections is observed as required, so as to improve the accuracy of the optimization design basis. sex.

Description of drawings

In order to illustrate the technical solutions of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention, which are common in the art. As far as technical personnel are concerned, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the structural schematic diagram of the observation device of the present invention;

Fig. 2 is the effect diagram of the direct shooting of the camera of the present invention: (a)～(d) are the shooting images at four different moments respectively;

Fig. 3 is the powder density distribution diagram obtained after the present invention takes 20 pictures at the powder beam focus;

Fig. 4 is the powder density distribution diagram obtained after taking 20 pictures at 2mm above the powder beam focus according to the present invention;

Fig. 5 is the powder density distribution diagram obtained after the present invention takes 20 pictures at 4 mm above the powder beam focus;

In the drawings: 1-camera; 2-lens; 3-retractable shield; 4-adapter; 5-powder feeding nozzle; 6-powder beam; 7-line light source; 8-powder collection box; 9-main body bracket; 10 - Industrial computer.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments.

Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work also fall within the protection scope of the present invention.

Referring to FIG. 1 , an observation device for powder density distribution provided by the present invention includes a support device. In this embodiment, the support device adopts a main frame 9 composed of a base plate and a column mounted on the base plate, and a powder collection box 8 is arranged on the base plate. , Install the camera 1, the lens 2, the telescopic cover 3, the adapter 4, the powder feeding nozzle 5 and the line light source 7 through the column.

The powder feeding nozzle 5 is arranged above the powder collecting box 8, and the powder is sprayed downward through the powder feeding nozzle 5 to form a powder bundle 6, and the powder collecting box 8 is used to continuously spray the powder. The camera 1 is arranged above the powder feeding nozzle 5. The camera 1 is connected to the rear end of the powder feeding nozzle 5 through the telescopic shield 3 through the downwardly arranged lens 2. The lens 2, the telescopic shield 3 and the powder feeding nozzle 5 are arranged on the same axis. superior. A line light source 7 is arranged on the column below the powder feeding nozzle 5 , and the light emission direction of the line light source 7 is perpendicular to the spraying direction of the powder beam 6 . The powder feeding nozzle 5 is connected to the column through the adapter 4. The adapter 4 can adjust the height of the powder feeding nozzle 5. The distance between the line light source 7 and the powder feeding nozzle 5 is equal to the working distance of the laser processing head. The light emission surface of the line light source 7 is the working surface. .

The telescopic shield 3 is made of opaque material to prevent light from entering the lens from around the shield; in addition, the telescopic shield 3 can be stretched, and the telescopic range is greater than the up and down movement range of the adapter 4 . The telescopic shield 3 is connected with the rear end of the powder feeding nozzle 5 through the adapter 4, the joint surface is tight, and the disassembly and assembly are convenient. The adapter 4 can be controlled by the industrial computer. The nozzles 5 are connected, and a through hole that can be observed by the lens 2 is processed between the upper and lower end faces.

The line light source 7 of the present invention can be a visible light source or an invisible light source, the power is not less than 1 mW, and the line width is not more than 5 mm. The wavelength band of the line light source 7 should be included in the response band of the camera 1 .

The camera 1 can be selected according to the line light source 7 , and the matching line light source 7 can also be selected according to the camera 1 .

When the observation device of the present invention is used, first, the line light source 7 is fixed at a certain height, and the position remains unchanged. Turn on the line light source 7 and the camera 1, and enter the observation state. When the powder feeder is turned on, the powder is ejected through the nozzle 5 to form a powder bundle 6 . At this time, the powder convergence at the cross section of the powder bundle can be observed in the camera 1 . By moving the adapter 4 up and down through the industrial computer 10 (the repeatability of the adapter 4 is less than or equal to 0.5mm), the nozzle 5 is driven to drive the powder beam to adjust the position, so that the distance between the line light source 7 and the powder feeding nozzle 5 is equal to the working distance of the laser processing head, Then the observed cross section is the working surface.

After the image of the powder density distribution of the present invention is collected, the following processing method can be used to obtain the definition optimization: the RBG values of the corresponding pixels of multiple photos are superimposed to obtain an average value, and the average value is assigned to a new image. Suppose the number of pixels of the new image is n, find the maximum value of R, the maximum value of G, and the maximum value of B in all pixels, denoted as Rmax, Gmax, Bmax, and obtain the proportional coefficient αr=255/Rmax, αg=255/Gmax, αb=255/Bmax. Multiply the R of each pixel of the new image by αr, the G of each pixel of the new image by αg, and the B of each pixel of the new image by αb. Obtain the final processed picture, which can clearly reflect the powder density distribution.

When the powder feeding nozzle is optimally designed, after the powder density distribution at the working surface is photographed, the powder density distribution at other cross-sections is observed and image-processed as needed, so as to support the optimization of the powder feeding nozzle. design.

The powder spots directly photographed by the camera of the device of the present invention are shown in Figures 2(a) to 2(d).

20 pictures are collected by camera 1 at the focus of the powder beam, and the effect after image processing is shown in Figure 3.

In this embodiment, referring to Figures 4-5, the height of the powder feeding nozzle 5 is adjusted through the adapter 4, and the powder density distribution map at 2 mm above the focus of the powder beam and the powder density at 4 mm above the focus of the powder beam are obtained by collecting and processing Distribution.

The measurement results can clearly reflect the powder density distribution at different cross-sections.

The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. , all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (8)

1. an observation device for powder density distribution, characterized in that: it comprises a main body support (9), the main body support (9) is made up of a base plate and a column installed on the base plate, the base plate is provided with a powder collection box (8), and the powder collects A powder feeding nozzle (5) is arranged above the box (8), the powder is formed by the powder feeding nozzle (5) to form a powder bundle (6) and is ejected downward, and the powder collecting box (8) is used to connect the ejected powder; A camera (1) is arranged above the nozzle (5), and the camera (1) is connected to the rear end of the powder feeding nozzle (5) through the lens (2) arranged downward through the telescopic shield (3), and the telescopic shield (3) can To prevent ambient light from entering the lens (2), the lens (2), the telescopic shield (3) and the powder feeding nozzle (5) are arranged on the same axis; the camera (1), the lens (2) , the telescopic shield (3) and the powder feeding nozzle (5) are installed through the column, and a line light source (7) is arranged on the column below the powder feeding nozzle (5). 6) The ejection direction is vertical; the powder feeding nozzle (5) is connected to the column through the adapter (4), and the adapter (4) can adjust the height of the powder feeding nozzle (5), so that the line light source (7) is connected to the powder feeding nozzle (5) The distance is equal to the working distance of the laser processing head, and the light emitting surface of the line light source (7) is the working surface. 2. The observation device for powder density distribution according to claim 1, wherein the telescopic shield (3) can be expanded and contracted with the movement of the powder feeding nozzle (5), and the expansion and contraction range is larger than that of the adapter (4) range of up and down motion. 3. The observation device for powder density distribution according to claim 1 or 2, characterized in that: the telescopic shield (3) is connected to the tail end of the powder feeding nozzle (5) through the adapter (4), and the adapter ( The upper end surface of 4) is connected with the telescopic shield (3), the lower end surface is connected with the powder feeding nozzle (5), and a through hole that can be observed by the lens (2) is processed between the upper and lower end surfaces. 4. The observation device for powder density distribution according to claim 1, characterized in that: the camera (1), the adapter (4) and the line light source (7) are connected to an industrial computer (10); the industrial computer (10) The adapter (4) is controlled to move up and down, the linear light source (7) is controlled to emit required light, and the image collected by the camera (1) is acquired, saved and processed. 5. The observation device of powder density distribution according to claim 1 is characterized in that: the power of the emitted light of the line light source (7) is not less than 1mW, the line width is not more than 5mm, and the wavelength band of the line light source is included in the camera ( 1) within the response band. 6 . The observation device for powder density distribution according to claim 1 , wherein the repeatability of the adapter ( 4 ) is less than or equal to 0.5 mm. 7 . 7. An image processing method for powder density distribution, characterized in that: based on the observation device of the powder density distribution according to claim 1, a plurality of photos are collected by a camera (1), and the RBG values of the corresponding pixels of the plurality of photos are collected. Superimpose the average value, and assign the average value to a new image; set the number of pixels in the new image to be n, find the maximum value of R, the maximum value of G, and the maximum value of B in all pixel points, and record For Rmax, Gmax, Bmax, obtain the proportional coefficient αr=255/Rmax, αg=255/Gmax, αb=255/Bmax; multiply the R of each pixel of the new image by αr, and for each pixel of the new image The G of the point is multiplied by αg, and the B of each pixel of the new image is multiplied by αb to obtain the final processed image. 8. A method for optimizing design of powder feeding nozzles, characterized in that: according to the image processing method of powder density distribution according to claim 6, the height of the powder feeding nozzle (5) is adjusted to obtain the outer surface of the laser processing head working surface. The powder density distribution at other cross-sections, and the powder distribution of the working face of the laser processing head and other upper and lower positions are combined to optimize the design of the powder feeding nozzle.

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