A sand mold printing process online monitoring device and method

Abstract

The present invention provides an online monitoring device for a sand mold printing process, comprising an industrial camera, a monitoring system industrial computer, a printer controller, a display and a printer nozzle, wherein the industrial camera is fixedly connected to the printer nozzle; the printing controller is electrically connected to the printer nozzle and controls its operation; the monitoring system industrial computer is electrically connected to the printer controller, the industrial camera and the display respectively. The present invention adopts a dynamic monitoring method, that is, the industrial camera moves with the printer nozzle to take pictures, and there is no need to monitor the entire workbench plane. The requirements for resolution and frame rate are not high. Two industrial cameras arranged on both sides of the printer nozzle monitor the status before and after printing respectively, so as to obtain a higher image monitoring quality and realize real-time monitoring of the sand mold printing process.

Description

Technical Field

[0001] The present invention belongs to the technical field of sand mold 3D printing equipment, and in particular relates to an online monitoring device and method for a sand mold printing process. Background Art

[0002] Sand mold printing technology has developed rapidly in the casting field in recent years due to its advantages such as high efficiency, low cost and flexible manufacturing. At present, there are four main sand mold printing process methods at home and abroad: Selective Laser Sintering (SLS), Three Dimensional Printing (3DP), Patternless Casting Manufacturing (PCM), and GS (Gener is Sand) technology.

[0003] Due to the low cost and good forming quality of 3DP technology, it has become the mainstream process method adopted by domestic and foreign manufacturers and has achieved mature industrialization. In recent years, with the continuous improvement of processing quality and processing accuracy, in the field of sand mold printing, there are many problems such as the need for repeated debugging before printing, poor consistency of print quality and uncontrollable process. However, in the field of sand mold printing, there has been no public report on the online monitoring system of sand mold printing process. Summary of the invention

[0004] In view of the defects and shortcomings in the prior art, the purpose of the present invention is to provide an online monitoring device and method for the sand mold printing process, which adopts machine vision technology to realize online monitoring of the sand mold printing status.

[0005] An online monitoring device for sand mold printing process, characterized by comprising an industrial camera, a monitoring system industrial computer, a printer controller, a display and a printer nozzle,

[0006] The industrial camera is fixedly connected to the printer nozzle;

[0007] The printer controller is electrically connected to the printer nozzle and controls its operation;

[0008] The industrial computer of the monitoring system is electrically connected to the printer controller, the industrial camera and the display respectively.

[0009] Preferably, the industrial camera includes a first camera and a second camera, the first camera and the second camera are respectively arranged on a first side and a second side of the printer nozzle, and the first camera and the second camera can move with the movement of the printer nozzle.

[0010] Preferably, the field of view of the industrial camera is not less than 1.2 times the printing size of the printer nozzle.

[0011] Preferably, the relationship between the frame rate fps of the industrial camera, the movement speed v of the printer nozzle and the camera field width L is: .

[0012] Preferably, the industrial camera is an area array CMOS camera or a CCD camera with a resolution of ≦1 mm / pixel.

[0013] A method for online monitoring of a sand mold printing process is implemented by using the device for online monitoring of a sand mold printing process, and the specific steps are as follows:

[0014] S1: The printer controller controls the printer nozzle to work and sends instructions to the monitoring system industrial computer;

[0015] S2: When the printer nozzle moves toward the first side to print, the first camera collects images of the sand-laying surface state, and the second camera collects images of the sand mold state after printing; when the printer nozzle moves toward the second side to print, the second camera collects images of the sand-laying surface state, and the first camera collects images of the sand mold state after printing;

[0016] S3: The images captured by the first camera and the second camera are transmitted to the industrial computer of the monitoring system in real time, and the image processing algorithm built into the industrial computer of the monitoring system analyzes and processes the captured images;

[0017] S4: According to the result of the image analysis processing in step S3, the defect type is displayed on the display and fed back to the sand printer controller through the monitoring system industrial computer for processing.

[0018] Preferably, the image analysis and processing method in step S4 includes image preprocessing, image segmentation, image enhancement, feature extraction and defect recognition performed in sequence.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The present invention adopts machine vision technology to realize online monitoring of sand mold printing status, and proposes the concept of online monitoring of sand mold printing process for the first time, so as to ensure that the sand mold printing process is controllable and the quality of sand mold parts can be traced and analyzed.

[0021] (2) The present invention fixes the industrial camera on the printer nozzle and adopts a dynamic monitoring method, that is, the industrial camera moves with the printer nozzle to take pictures. There is no need to monitor the entire workbench plane, and the requirements for resolution and frame rate are not high. Due to real-time local photography, the image monitoring quality is relatively high. By promptly handling problems that arise during the printing process, on the one hand, a lot of work for printer debugging and preparation is reduced, thereby improving work efficiency; on the other hand, it avoids large-scale printed parts from being scrapped due to defects after they are formed, thereby reducing production costs.

[0022] (3) The present invention has a wide range of applications. It is not only suitable for sand mold printing, but also can be applied to 3DP printing of other materials. The device has a simple structure, low performance requirements and is easy to operate, which can greatly improve the monitoring efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of an online monitoring device for a sand mold printing process according to the present invention;

[0024] Figure 2 A flow chart of the detection steps of an online monitoring method for a sand mold printing process according to the present invention;

[0025] The reference numerals of the present invention are listed as follows:

[0026] 1-industrial camera, 2-camera fixing bracket, 3-printer nozzle, 4-truss, 5-display, 6-monitoring system industrial computer, 7-wire, 8-printer controller;

[0027] 1-1 is the first camera, 1-2 is the second camera. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is described below in conjunction with the accompanying drawings and embodiments:

[0029] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0030] At the same time, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is 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 orientation, be constructed and operated in a specific orientation, and are not used to limit the scope of the present invention. The change or adjustment of the relative relationship should also be regarded as the scope of the present invention without substantially changing the technical content. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features shown. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly indicate the number of technical features indicated. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0031] The invention provides an on-line monitoring device and method for a sand mold printing process, and adopts image processing technology to realize on-line monitoring of the sand mold printing state.

[0032] The present invention is further described below in conjunction with the accompanying drawings.

[0033] Example 1

[0034] like Figure 1 As shown, an online monitoring device for a sand mold printing process includes an industrial camera 1, a monitoring system industrial computer 6, a printer controller 8, a display 5 and a printer nozzle 3. The industrial camera 1 is fixedly connected to the printer nozzle 3 via a camera fixing bracket 2; the printer nozzle 3 is arranged on a truss 4 via a slide rail, and the printer nozzle 3 can move on the truss 4 along the direction where the truss 4 is located.

[0035] The printer controller 8 is electrically connected to the printer nozzle 3 via a wire 7 and controls its operation;

[0036] The monitoring system industrial computer 6 is electrically connected to the printer controller 8 , the industrial camera 1 and the display 5 through wires.

[0037] The printer controller 8 is used to control the movement, speed and trajectory of the printer nozzle 3;

[0038] The monitoring system industrial computer 6 is used to obtain the image captured by the industrial camera 1, analyze and process it, and feed back the processing result to the sand printer controller 8;

[0039] The display 5 is used to display the current shooting picture in real time, and provide the current sanding status and printing status and processing results.

[0040] The size of the printer nozzle 3 in this embodiment is 120 mm×120 mm.

[0041] Among them, the industrial computer 6 of the monitoring system uses Advantech IPC610.

[0042] Specifically, the industrial camera 1 includes a first camera 1-1 and a second camera 1-2. The first camera 1-1 and the second camera 1-2 are respectively arranged on the first side and the second side of the printer nozzle. The first camera 1-1 and the second camera 1-2 can move with the movement of the printer nozzle 3, so as to collect the sand laying state and the sand mold printing state of the sand bed when the printer nozzle 3 moves.

[0043] Specifically, the field of view area of ​​the industrial camera 1 is not less than 1.2 times the printing size of the printer nozzle 3, ensuring that the industrial camera 1 can completely capture the printing area.

[0044] Specifically, the relationship between the frame rate fps of the industrial camera 1, the moving speed v of the printer nozzle 3, and the camera field width L is: , can ensure that the device can achieve continuous stability of the monitoring image.

[0045] Specifically, the characteristic parameters of the first camera 1-1 and the second camera 1-2 are the same, the industrial camera 1 is an area array CMOS camera or a CCD camera, equipped with a corresponding lens, and the field of view width L is 144mm; the pixel is not less than 1440×1440 pixels; the moving speed v of the printer nozzle 3 is 2m / s; the camera frame rate is ≥13.9fps; the resolution is not greater than 1mm / pixel; and the object distance is set to 100mm.

[0046] Specifically, industrial camera 1 selects Daheng Image MER-U3-L series MER-502-79U3M-L POL model camera with a resolution of 2448 (H) × 2048 (V), a frame rate of 79fps, and a target size of 2 / 3".

[0047] The lens selected is the Daheng Image fixed-focus lens Schneider Apo-Xenoplan 1.4 / 23, with a focal length of 23mm and a working distance greater than 86mm.

[0048] A method for online monitoring of a sand mold printing process is implemented based on an online monitoring device for a sand mold printing process, and the specific steps are as follows:

[0049] S1: The printer controller 8 controls the printer nozzle 3 to work and sends instructions to the monitoring system industrial computer 6;

[0050] S2: When the printer nozzle 3 moves toward its first side to print, the first camera 1-1 collects images of the sand-laying surface state, and the second camera 1-2 collects images of the sand mold state after printing; when the printer nozzle 3 moves toward its second side to print, the second camera 1-2 collects images of the sand-laying surface state, and the first camera 1-1 collects images of the sand mold state after printing;

[0051] S3: The images captured by the first camera 1-1 and the second camera 1-2 are transmitted to the monitoring system industrial computer 6 in real time, and the image processing algorithm built into the monitoring system industrial computer 6 analyzes and processes the captured images;

[0052] S4: According to the result of the image analysis processing in step S3, the defect type is displayed on the display 5 and fed back to the sand printer controller 8 through the monitoring system industrial computer 6 for processing.

[0053] Specifically, the image analysis and processing method in step S3 includes image preprocessing, image segmentation, image enhancement, feature extraction and defect recognition performed in sequence.

[0054] Images collected at industrial sites usually contain noise. The main purpose of image preprocessing is to reduce noise and improve image quality to make it more suitable for human observation or machine processing.

[0055] Image segmentation is the technology and process of dividing an image into several specific regions with unique properties and proposing objects of interest. It is a key step from image processing to image analysis.

[0056] Image enhancement is to enhance the useful information in the image, purposefully emphasize the overall or local characteristics of the image, improve the image quality, enrich the amount of information, strengthen the image interpretation and recognition effect, and meet the needs of certain special analysis.

[0057] Feature extraction can be understood as a mapping from high-dimensional image space to low-dimensional feature space. Its effectiveness has a significant impact on the subsequent defect target recognition accuracy, computational complexity, robustness, etc. The basic idea is to make the target have smaller intra-class convergence and larger inter-class convergence in the obtained subspace.

[0058] Defect recognition, based on the above-mentioned image feature extraction, adopts supervised learning pattern recognition, which mainly includes classifiers based on probability statistics, linear classifiers, artificial neural network classifiers and support vector machines, etc., which can realize the identification of defect types in the sand laying state and sand mold printing process.

[0059] Specifically, in step S4, the defect type is identified and corresponding processing is performed, including continuing printing, real-time alarm, stopping production, re-sanding, taking manual remedial measures or re-printing, including at least one of the above processing methods.

[0060] After the defect type is identified and fed back to the printer controller, the following processing is performed:

[0061] (1) When the defect type is streaks, the printer controller 8 controls the printer nozzle 3 to stop working and manually adjusts the sanding state;

[0062] (2) When the defect type is sand pile, the solution is to re-sand;

[0063] (3) When the defect type is a crack, the printer controller 8 controls the printer nozzle 3 to suspend operation until the problem is eliminated and then resume operation;

[0064] (4) When the defect type is a small pit, the printer controller 8 controls the printer nozzle 3 to continue printing;

[0065] (5) When the defect type is a large boss, the printer controller 8 controls the printer nozzle 3 to stop working and alarm.

[0066] Specifically, in step S4, the defect type is identified, and if a defect is found, the defect definition is performed; if there is no defect, image acquisition continues; if the defect cannot be identified, printing is continued, and image acquisition is performed again after the subsequent optimization algorithm.

[0067] The above method can realize online monitoring of the sand mold printing process. The popular monitoring technology solutions in the field of metal additive manufacturing are that the camera is fixed on the top window or side window of the forming cabin, and the transition time interval between adjacent layers is used to monitor the powder spreading or printing status of a certain layer. The frame rate and resolution of the camera are very high. It is difficult to apply to large-size sand mold printing; this technical solution fixes the camera on the printer nozzle 3 and adopts a dynamic monitoring method, that is, the camera moves with the printer nozzle 3 to take pictures, and there is no need to monitor the entire workbench plane. The requirements for resolution and frame rate are not high, but the image monitoring quality is high.

[0068] The application of this technical solution and this patent is not limited to sand mold printing, and can be used for 3DP printing of other materials.

[0069] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

[0070] Many other changes and modifications may be made without departing from the concept and scope of the present invention.It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for online monitoring of a sand mold printing process, characterized in that: The method is realized by using an online monitoring device based on the sand mold printing process, which includes: an industrial camera, an industrial computer of a monitoring system, a printer controller, a display and a printer nozzle, wherein the industrial camera is fixedly connected to the printer nozzle; The printer controller is electrically connected to the printer nozzle and controls its operation; The industrial computer of the monitoring system is electrically connected to the printer controller, the industrial camera and the display respectively; The industrial camera comprises a first camera and a second camera, the first camera and the second camera are respectively arranged on a first side and a second side of the printer nozzle, and the first camera and the second camera can move with the movement of the printer nozzle; The specific steps are as follows: S1: The printer controller controls the printer nozzle to work and sends instructions to the monitoring system industrial computer; S2: When the printer nozzle moves toward the first side to print, the first camera collects images of the sand-laying surface state, and the second camera collects images of the sand mold state after printing; when the printer nozzle moves toward the second side to print, the second camera collects images of the sand-laying surface state, and the first camera collects images of the sand mold state after printing; S3: The images captured by the first camera and the second camera are transmitted to the industrial computer of the monitoring system in real time, and the image processing algorithm built into the industrial computer of the monitoring system analyzes and processes the captured images; S4: According to the result of the image analysis processing in step S3, the defect type is displayed on the display and fed back to the sand printer controller through the industrial computer of the monitoring system for processing; In step S4, the defect type is identified and corresponding processing is performed, including continuing printing, real-time alarm, stopping production, re-sanding, taking manual remedial measures or re-printing; After the defect type is identified and fed back to the printer controller, the following processing is performed: (1) When the defect type is streaks, the printer controller controls the printer nozzle to stop working and manually adjusts the sanding state; (2) When the defect type is sand pile, the solution is to re-sand; (3) When the defect type is a crack, the printer controller controls the printer nozzle to suspend operation until the problem is eliminated and then resume operation; (4) When the defect type is a small pit, the printer controller controls the printer nozzle to continue printing; (5) When the defect type is a large boss, the printer controller controls the printer nozzle to stop working and alarm.

2. The method for online monitoring of sand mold printing process according to claim 1, characterized in that: The field of view of the industrial camera is not less than 1.2 times the printing size of the printer nozzle.

3. The method for online monitoring of sand mold printing process according to claim 1, characterized in that: The relationship between the frame rate fps of the industrial camera, the movement speed v of the printer nozzle and the camera field width L is:

4. The method for online monitoring of sand mold printing process according to claim 1, characterized in that: The industrial camera is an area array CMOS camera or a CCD camera with a resolution of ≦1mm / pixel.

5. The method for online monitoring of sand mold printing process according to claim 1, characterized in that: The image analysis and processing method in step S3 includes image preprocessing, image segmentation, image enhancement, feature extraction and defect recognition performed in sequence.

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