A method for evaluating defects of aluminum alloy castings

Abstract

The present invention provides a method for defect assessment of aluminum alloy castings. The steps include: obtaining the X-ray radiograph image of the workpiece; obtaining the thickness H of the radiographed part; obtaining the magnification factor M of the obtained X-ray radiograph image relative to the actual radiographed part; performing a reduction process on the obtained X-ray radiograph image to obtain a reduced image; extracting the defects and their characteristic parameters on the obtained reduced image, classifying the extracted defects in combination with the obtained thickness H of the radiographed part, comparing with the defects on the standard image, and outputting the defect assessment result according to the comparison result. The present invention is an intelligent assessment method for defect grading based on the national standard GB / T 11346. With a recognized standard as the basis, the obtained defect assessment result has good accuracy and high credibility. By adopting the solution of the present invention, it is possible to quickly and specifically perform defect assessment on the local part of the aluminum alloy casting.

Description

Technical Field

[0001] The present invention belongs to the technical field of defect assessment of cast aluminum alloys, and particularly relates to a method for assessing defects in aluminum alloy castings. Background Art

[0002] Inspecting the internal quality of aluminum alloy castings is an essential step. Reasonably classifying the internal defects of aluminum alloy castings can not only optimize the production process, but also evaluate the quality of parts in mass production, serving as a key basis for both the supplier and the demander to determine whether the quality of the castings is qualified.

[0003] Currently, the defect grade assessment of aluminum alloy castings is carried out according to the standard "GB / T 11346 Classification of Defects for Radiographic Testing of Aluminum Alloy Castings". This national standard is applicable to X-ray film radiographic testing and is currently the reference standard with the best credibility. However, film radiographic testing has problems such as "inability to form images in real time and quickly, slow detection speed, long detection cycle, its developing solution pollutes the environment, high film price, cumbersome management and retrieval, and limited storage life".

[0004] With the development of intelligent detection technology, X-ray real-time imaging detection technology has been gradually developed. It has the advantages of convenient operation, easy storage of photos, and low cost, and is expected to replace film imaging. However, during X-ray real-time imaging detection, there is always a certain distance between the detector and the casting, and the obtained radiographic image is significantly different from the film image, which brings difficulties to defect grade assessment. Directly assessing the defect grade according to the national standard GB / T 11346 cannot obtain accurate assessment results.

[0005] In the prior art, the technology for intelligent evaluation of radiographic images has gradually matured. For example: The intelligent defect rating method for X-ray imaging images based on industrial scenarios developed by Hangzhou Peimu Technology Co., Ltd.: Cut the image to be tested according to a fixed width to obtain a to-be-tested image with a standard square size, put the to-be-tested image with the standard square size into an image recognition model to obtain the defect mask and defect category of the to-be-tested image; perform inverse transformation on the defect mask and restore the mask image size to complete the recombination of the mask image and obtain the defect area; synthesize the defect area and defect category of the to-be-tested image to generate a defect distribution hologram of the to-be-tested image, and use the defect level evaluation module to complete the defect rating work of the entire to-be-tested image. Among them, the image recognition model is trained and generated by multiple initial images with standard square sizes and the defect area annotations and defect type annotations corresponding to each initial image with a standard square size. The initial images with standard square sizes include defect-free type images and defective images containing various defect types, and the initial images with standard square sizes are obtained by cutting the initial X-ray imaging images according to a fixed width. Another example is that Jiangsu Maritime Institute provides a method for evaluating welding defect negatives in industrial X-ray flaw detection, which manually inputs the information of the welding defect negative on the computer side and outputs the defect grade of the welding defect negative through the computer. Still another example is that Shanghai University of Engineering Science has developed an automatic recognition method for X-ray images of casting defects based on an improved neural network: Input several obtained X-ray images of castings, perform image preprocessing on the images, label the defects in each preprocessed image, and randomly select them according to a ratio to form a training set and a validation set; construct an improved convolutional neural network model based on YOLOv5, including adding a channel attention mechanism module SENet and optimizing the loss function; use the training set to train the improved convolutional neural network model based on YOLOv5; after iterating N times, use the trained model to complete the defect recognition of the X-ray images in the validation set, and compare the recognition results of various comparison models. However, these technologies must be based on accurate radiographic images to obtain accurate evaluation results, and essentially solve the problem of image recognition. Therefore, based on the existing technology for intelligent evaluation of radiographic images, it is necessary to develop a more accurate and reliable method for evaluating defects in aluminum alloy castings.

[0006] More critically, using the existing detection methods and methods for evaluating defects in aluminum alloy castings, it is impossible to quickly and specifically evaluate the defects in the local area of aluminum alloy castings, especially it is impossible to accurately and quickly evaluate the local area of plate-shaped castings and cylindrical castings. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for evaluating defects in aluminum alloy castings with good accuracy, high reliability and high efficiency.

[0008] To achieve the foregoing objectives, the present invention adopts the following technical solutions.

[0009] A method for evaluating defects in aluminum alloy castings, characterized in that the steps include:

[0010] Step 1, obtaining an X-ray radiograph of the workpiece by means of an automatic detection device;

[0011] Step 2, obtaining the thickness H of the radiographed part;

[0012] Step 3, obtaining the magnification M of the obtained X-ray radiograph relative to the actual radiographed part;

[0013] Step 4, according to the obtained magnification M, reducing the obtained X-ray radiograph to obtain a reduced image;

[0014] Step 5, extracting the defects and their characteristic parameters on the obtained reduced image by means of image feature extraction software, classifying the extracted defects in combination with the obtained thickness H of the radiographed part, and comparing them with the defects on the standard image, and outputting a defect evaluation result according to the comparison result; the standard image refers to the defect evaluation image in the aluminum alloy casting defect evaluation standard. In this step, the image feature extraction software is a prior art, and by means of this software, the defects and characteristic parameters on the radiograph can be automatically extracted, the defects can be classified and compared. In the present invention, the magnification refers to the ratio of the area of the obtained X-ray radiograph to the area of the actual radiographed part. For example, if the size of the obtained X-ray radiograph is 10 cm * 20 cm and the size of the actual radiographed part image is 5 cm * 10 cm, then the magnification is 10 * 20 / 5 * 10 = 4 times. Correspondingly, when performing defect evaluation, the size of the obtained X-ray radiograph should be reduced to 5 cm * 10 cm.

[0015] In order to obtain the thickness H of the radiographed part more efficiently, accurately and in real time, in Step 2,

[0016] For the workpiece placed vertically, the distance S1 from the X-ray source to the front of the radiographed part is measured by the first distance sensor installed near the X-ray source of the automatic detection device, the distance S2 from the detector window to the back of the radiographed part is measured by the second distance sensor installed near the detector of the automatic detection device, and the distance L between the X-ray source and the detector window is measured by the third distance sensor installed near the X-ray source of the automatic detection device; and the thickness H of the radiographed part is calculated according to formula (Ⅱ);

[0017] H = L - S1 - S2 ………………… (Ⅱ)

[0018] In Step 3, the magnification M of the obtained X-ray radiograph relative to the actual radiographed part is calculated according to formula (Ⅰ);

[0019] M = 1 + S2 / S1…………………(Ⅰ)

[0020] For a horizontally placed workpiece, the height h1 between the fixed plane and the upper surface of the workpiece (substantially the upper surface of the radiographed part, the same below) is measured by the fourth distance sensor installed on the automatic detection device, the height h2 between the fixed plane and the lower surface of the workpiece is measured by the fifth distance sensor installed on the automatic detection device, the height h3 between the fixed plane and the horizontal plane where the detector window is located is measured by the sixth distance sensor installed on the automatic detection device, and the height h4 between the detector window and the upper surface of the workpiece is measured by the seventh distance sensor near the detector installed on the automatic detection device; and the thickness H of the radiographed part is calculated according to formula (Ⅲ).

[0021] H = h2 - h1…………………(Ⅲ)

[0022] In step 3, the magnification M of the X-ray radiographed image relative to the actual radiographed part is calculated according to formula (Ⅳ).

[0023] M = 1 + (h3 - h2) / h4…………………(Ⅳ)

[0024] Further, the steps of obtaining the X-ray radiographed image in step 1 include:

[0025] Step 11, obtain the three-dimensional model of the workpiece and establish a three-dimensional model coordinate system;

[0026] Step 12, obtain the workpiece coordinate system of the workpiece in the detection state after being in place, and calculate the conversion relationship between the workpiece coordinate system and the three-dimensional model coordinate system;

[0027] Step 13, select the model part that needs to be X-ray detected in the three-dimensional model of the workpiece;

[0028] Step 14, combine the coordinates of the selected model part and the obtained conversion relationship to obtain the coordinates of the actual part on the workpiece that needs to be X-ray detected;

[0029] Step 15, control the X-ray source of the automatic detection device to move to the target detection position, and control the detector of the automatic detection device to move to the target receiving position;

[0030] Step 16, perform the X-ray radiography process, and store the X-ray radiographed image in the computer system;

[0031] Step 17, according to steps 13 - 16, radiograph the remaining parts on the workpiece that need to be X-ray detected.

[0032] Preferably, for a cylindrical aluminum alloy casting, the workpiece coordinate system is established with the top wall or bottom wall of the aluminum alloy casting as the workpiece plane coordinate system; after selecting the model part that needs to be X-ray detected, the actual part plane coordinates on the workpiece that need to be X-ray detected are obtained by combining the corresponding coordinates of the selected model part and the obtained conversion relationship; when performing the X-ray radiography process, all radiography is performed along the axial direction of the workpiece at the actual part plane coordinates.

[0033] Preferably, for a plate-shaped aluminum alloy casting, the workpiece plane approximate coordinate system is established with the horizontal plane where the highest point of the top wall of the aluminum alloy casting is located as the workpiece coordinate system; after selecting the model part that needs to be X-ray detected, the actual part plane coordinates on the workpiece that need to be X-ray detected are obtained by combining the corresponding coordinates of the selected model part and the obtained conversion relationship.

[0034] In order to more conveniently evaluate the defects of the local part of the aluminum alloy casting, the three-dimensional model of the workpiece is divided into several standard areas (which can also be understood as dividing the three-dimensional model into several independent small modules according to fixed dimensions), and each standard area corresponds to the effective detection area of a single detection.

[0035] In the present invention, the automatic detection device includes an X-ray generator and an X-ray receiver arranged in a shielding room. The X-ray receiver converts the received signal into an image signal and displays it through a display terminal;

[0036] A rotatable workpiece carrier is arranged in the shielding room. The workpiece carrier and its rotating mechanism are connected to a driving mechanism. The driving mechanism drives the workpiece carrier and its rotating mechanism to move along the track. The track extends from the inside of the shielding room to the vicinity of the automatic loading and unloading system; the X-ray generator is arranged on a position adjusting mechanism, and the position adjusting mechanism is installed on the top of the shielding room;

[0037] The rotating mechanism, the driving mechanism, the automatic feeding system, and the position adjusting mechanism are respectively connected to a computer control system. A program that can run on a processing module is stored in the storage module of the computer control system. When the processing module executes the program, it can at least implement the following functions / steps:

[0038] Control the workpiece carrier and its rotating mechanism to move along the track to a preset position;

[0039] Control the workpiece carrier to rotate at a preset angle;

[0040] Control the automatic loading and unloading system to transfer the workpiece to the workpiece carrier and control the automatic loading and unloading system to remove the workpiece from the workpiece carrier;

[0041] Control the X-ray generator to move to the target detection position and rotate at a preset speed;

[0042] The position adjusting mechanism includes a rotating shaft vertically installed at the top of the shielding room. The upper end of the rotating shaft is connected to a motor, and the lower end of the rotating shaft is connected to the middle of a horizontally arranged cross beam. Two two-dimensional moving mechanisms are arranged on the cross beam. An X-ray generator A is installed on the two-dimensional moving mechanism A, and an X-ray receiver A is installed on the two-dimensional moving mechanism B. By controlling the two-dimensional moving mechanism, the X-ray generator A and the X-ray receiver A can be adjusted to the same height and arranged facing each other. The window orientation of the X-ray receiver A is in the horizontal direction. By controlling the rotation of the motor, the X-ray generator A1 and the X-ray receiver A can be driven to rotate synchronously;

[0043] The two-dimensional moving mechanism A includes a first horizontal lead screw and a first vertical lead screw. A first movable seat is fitted on the first horizontal lead screw. The first vertical lead screw is connected to the first movable seat. A second movable seat is fitted on the first vertical lead screw. A vertically arranged first connecting rod is provided on the second movable seat. The X-ray generator A is installed at the lower part of the first connecting rod. The two-dimensional moving mechanism B includes a second horizontal lead screw and a second vertical lead screw. A third movable seat is fitted on the second horizontal lead screw. The second vertical lead screw is connected to the third movable seat. A fourth movable seat is fitted on the second vertical lead screw. A vertically arranged second connecting rod is provided on the fourth movable seat. The X-ray receiver A is installed at the lower part of the second connecting rod. The centers of the X-ray generator A, the X-ray receiver A, the axis of the first vertical lead screw, the axis of the second vertical lead screw, and the axis of the rotating shaft are located in the same vertical plane;

[0044] An X-ray generator B is further provided at the lower part of the first connecting rod. The window orientation of the X-ray generator B is vertically downward. An X-ray receiver B is provided on the workpiece bearing table. The diameter of the X-ray receiver B is larger than the length of the workpiece. An acrylic plate and / or a foam pad for placing the workpiece are provided on the surface of the X-ray receiver B;

[0045] The workpiece bearing table is circular and coaxially arranged with the rotating shaft.

[0046] Further, for the transverse part on the plate-shaped aluminum alloy casting that needs to be defect-evaluated, after controlling the X-ray generator B to move to the detection starting point, control the X-ray generator B to move horizontally at a preset speed until the radiography is completed.

[0047] Furthermore, for the longitudinal part of the plate-shaped aluminum alloy casting that needs to be defect-evaluated, after controlling the X-ray generator B to move to the detection starting point, control the X-ray generator B to rotate at a preset speed until the radiography is completed, and the rotation center is located on the extension line of the rotating shaft; during one or more rotations of the X-ray generator B, the effective radiography area of the X-ray generator B completely covers the longitudinal part that needs to be defect-evaluated. For the vertical part of the cylindrical aluminum alloy casting that needs to be defect-evaluated, after controlling the X-ray generator A to move to the detection starting point, control the X-ray generator A to move vertically at a preset speed until the radiography is completed.

[0048] Beneficial effects: The present invention is an intelligent evaluation method for defect grade evaluation in accordance with the national standard GB / T 11346. With a recognized standard as the basis, the obtained defect evaluation results have good accuracy and high credibility; adopting the solution of the present invention, it is possible to quickly and specifically perform defect evaluation on the local part of the aluminum alloy casting, especially to accurately and quickly perform defect evaluation on the local part of the plate-shaped casting and the cylindrical casting; adopting the solution of the present invention, there is no need to use expensive high-precision small robots to be arranged in the detection area to control the movement of the X-ray generator and the X-ray receiver to the target position. Only by cooperating with a specific position adjustment mechanism and a specific detection path can the local part of the aluminum alloy casting be accurately radiographed. The detection cost is low, the control process is simple, and the control difficulty is small, especially suitable for defect evaluation of batch aluminum alloy castings. Description of the Drawings

[0049] Figure 1 Schematic diagram of the external structure of the automatic detection equipment in the embodiment;

[0050] Figure 2 Schematic diagram of the partial internal structure of the automatic detection equipment in the embodiment;

[0051] Figure 3 Schematic diagram of the position adjustment mechanism of the automatic detection equipment in the embodiment Figure 1 ;

[0052] Figure 4 Schematic diagram of the position adjustment mechanism of the automatic detection equipment in the embodiment Figure 2 ;

[0053] Figure 5 Schematic diagram of the working state of the automatic detection equipment in the embodiment Figure 1 (Obtaining the radiography image of the cylindrical aluminum alloy casting);

[0054] Figure 6 Schematic diagram of the working state of the automatic detection equipment in the embodiment Figure 2 (Obtaining the radiography image of the plate-shaped aluminum alloy casting);

[0055] Figure 7 Schematic diagram of the path for obtaining the radiographic image of the transverse part of the plate-shaped aluminum alloy casting in the embodiment;

[0056] Figure 8 Schematic diagram of the path for obtaining the radiographic image of the longitudinal part of the plate-shaped aluminum alloy casting in the embodiment;

[0057] Figure 9 Schematic diagram of the path for obtaining the partial radiographic image of the cylindrical aluminum alloy casting in the embodiment;

[0058] Figure 10 、 Figure 11 Schematic diagram of obtaining the thickness H of the radiographed part in the embodiment. Specific embodiments

[0059] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0060] Embodiment

[0061] In this embodiment, the automatic detection equipment will be described first. As Figures 1 to 4 shown, the automatic casting defect detection equipment includes a shielding room 3 with an automatic control door, an X-ray generator 1 and an X-ray receiver arranged in the shielding room 3. The X-ray generator 1 and the X-ray receiver are both connected to a supporting computer control system. The X-ray receiver converts the received signal into an image signal and displays it through a display terminal. Technicians can evaluate the defects by observing the displayed image. The X-ray generator 1, the X-ray receiver and the computer control system are commercially available complete sets of equipment, and their principles and specific structures will not be elaborated.

[0062] A rotatable workpiece carrier 4 is arranged in the shielding room 3. The workpiece carrier 4 and its rotating mechanism are connected to a driving mechanism. The driving mechanism drives the workpiece carrier 4 and its rotating mechanism to move along the track 5. The track 5 extends from inside the shielding room 3 to the vicinity of the automatic loading and unloading system; the X-ray generator 1 is arranged on a position adjusting mechanism, and the position adjusting mechanism is installed on the top inside the shielding room 3;

[0063] The rotating mechanism, the driving mechanism, the automatic feeding system (the automatic feeding system uses a six-axis robot 8), and the position adjusting mechanism are respectively connected to the computer control system. A program capable of running on the processing module is stored in the storage module of the computer control system. When the processing module executes the program, it can at least implement the following functions / steps:

[0064] Control the workpiece carrier 4 and its rotating mechanism to move along the track 5 to a preset position;

[0065] Control the workpiece carrier 4 to rotate at a preset angle;

[0066] Control the automatic loading and unloading system to transfer the workpiece to the workpiece carrier 4, and control the automatic loading and unloading system to remove the workpiece from the workpiece carrier 4;

[0067] Control the X-ray generator 1 to move to the target detection position and rotate at a preset speed.

[0068] Among them, the position adjustment mechanism includes a rotating shaft 10 vertically installed on the top of the shielding room 3. The upper end of the rotating shaft 10 is connected to the motor 11, and the lower end of the rotating shaft 10 is connected to the middle of the horizontally arranged cross beam 12. Two two-dimensional moving mechanisms are arranged on the cross beam 12. The X-ray generator A1 is installed on the two-dimensional moving mechanism A, and the X-ray receiver A2 is installed on the two-dimensional moving mechanism B. By controlling the two-dimensional moving mechanism, the X-ray generator A1 and the X-ray receiver A2 can be adjusted to the same height and arranged face to face. The window orientation of the X-ray receiver A2 is the horizontal direction. By controlling the rotation of the motor 11, the cross beam 12, the X-ray generator A1 and the X-ray receiver A2 can be driven to rotate synchronously.

[0069] Among them, the two-dimensional moving mechanism A includes a first horizontal lead screw 13 and a first vertical lead screw 14. A first movable seat 22 is fitted on the first horizontal lead screw 13. The first vertical lead screw 14 is connected to the first movable seat 22. A second movable seat 17 is fitted on the first vertical lead screw 14. A vertically arranged first connecting rod 18 is provided on the second movable seat 17. The X-ray generator A1 is installed at the lower part of the first connecting rod 18. The two-dimensional moving mechanism B includes a second horizontal lead screw 15 and a second vertical lead screw 16. A third movable seat 19 is fitted on the second horizontal lead screw 15. The second vertical lead screw 16 is connected to the third movable seat 19. A fourth movable seat 20 is fitted on the second vertical lead screw 16. A vertically arranged second connecting rod 21 is provided on the fourth movable seat 20. The X-ray receiver A2 is installed at the lower part of the second connecting rod 21. The center of the X-ray generator A1, the center of the X-ray receiver A2, the axis of the first vertical lead screw 14, the axis of the second vertical lead screw 16 and the axis of the rotating shaft 10 are located in the same vertical plane. Among them, the rotation of the first horizontal lead screw 13 is driven by the motor 35, the rotation of the first vertical lead screw 14 is driven by the motor 34, the rotation of the second horizontal lead screw 15 is driven by the motor 30, and the rotation of the second vertical lead screw 16 is driven by the motor 33. The first vertical lead screw 14 is installed on the mounting plate 32, and the second vertical lead screw 16 is installed on the mounting plate 31.

[0070] Among them, an X-ray generator B 6 is further provided at the lower part of the first connecting rod 18. The window of the X-ray generator B 6 faces vertically downward, and the window of the X-ray generator B 6 is not lower than the lower end of the first connecting rod 18. An X-ray receiver B7 is provided on the workpiece carrying table 4. The upper surface (effective detection surface) of the X-ray receiver B7 is circular, the diameter of the X-ray receiver B7 is larger than the length of the workpiece, and an acrylic plate or a foam pad for placing the workpiece (the acrylic plate or the foam pad is shown as No. 23 in the attached drawing) is provided on the surface of the X-ray receiver B 7, or an acrylic plate is first provided on the surface of the X-ray receiver B 7, and then a foam pad is placed on the acrylic plate. The thickness and strength of the acrylic plate or the foam pad can be selected according to the workpiece specifications, and it is necessary to ensure that it will not be cracked when placing the workpiece. The upper surface area of the acrylic plate is the same as the upper surface area of the workpiece carrying table 4. In this embodiment, the X-ray receiver B 7, the acrylic plate and the foam pad are installed by positioning pins, and these three components and the positioning pins can be flexibly removed and installed.

[0071] Among them, the workpiece carrying table 4 is circular, and the workpiece carrying table 4 and the rotating shaft 10 are coaxially arranged.

[0072] Among them, the X-ray generator A1 and the X-ray receiver A 2 are used in combination, and the X-ray generator B 6 and the X-ray receiver B7 are used in combination. When only the X-ray generator A1 and the X-ray receiver A 2 need to be used, the "X-ray receiver B 7, the acrylic plate and the foam pad" and the positioning pins can be removed. When only the X-ray generator B 6 and the X-ray receiver B7 need to be used, the X-ray receiver A 2 can be moved to the upper limit position.

[0073] In order to obtain the thickness H of the penetrated part more efficiently, accurately and in real time, in one of the solutions in this embodiment: a first distance sensor is installed near the X-ray generator A1 to measure the vertical distance S1 between the window of the X-ray generator A1 and the surface of the penetrated part, a second distance sensor is installed near the X-ray receiver A 2 to measure the vertical distance S2 between the window of the X-ray receiver A 2 and the back surface of the penetrated part, and a third distance sensor is installed near the X-ray generator A1 to measure the distance L between the windows of the X-ray receiver A 2 detectors. Each sensor is connected to a computer control system and automatically calculates the thickness H of the penetrated part (H = L - S1 - S2). The calculation basis is shown in Figure 10 As shown, this solution is applicable to the single-wall penetration of vertically arranged workpieces, and automatically calculates the magnification M of the obtained X-ray penetration image relative to the actual penetrated part, M = 1 + S2 / S1.

[0074] In order to obtain the thickness H of the radiographed part more efficiently, accurately and in real time, the second solution in this embodiment: install a fourth distance sensor, a fifth distance sensor and a sixth distance sensor on the bottom wall of the cross beam 12. The light sources of these three sensors are arranged at the same height and have the same specifications. Measure the height h1 between the fixed plane and the upper surface of the workpiece through the fourth distance sensor, measure the height h2 between the fixed plane and the lower surface of the workpiece through the fifth distance sensor, and measure the height h3 between the fixed plane and the upper surface of the workpiece carrier 4 through the sixth distance sensor. This fixed plane refers to the horizontal plane where the light sources of these three sensors are located. The lower surface of the workpiece and the upper surface of the acrylic plate or foam pad on which the workpiece is placed are regarded as the same plane. A seventh sensor is installed near the X-ray generator B6 to measure the vertical height h4 between the window of the X-ray generator B6 and the upper surface (radiographed part) of the workpiece. Each sensor is connected to the computer control system, and automatically calculates the thickness H of the radiographed part (H = h2 - h1), and automatically calculates the magnification M of the obtained X-ray radiograph relative to the actual radiographed part. M = 1 + (h3 - h2) / h4. The calculation basis is shown in Figure 11 As shown, this solution is applicable to single-wall radiography of horizontally placed workpieces;

[0075] During use: adjust the distance between the first movable seat 22 and the third movable seat 19 by adjusting the rotation of the motor 35 and / or the motor 30, so as to adjust the distance between the overall structure of "mounting plate 32, first vertical lead screw 14, second movable seat 17, first connecting rod 18, X-ray generator A1" and the overall structure of "mounting plate 31, second vertical lead screw 16, fourth movable seat 20, second connecting rod 21, X-ray receiver A2"; adjust the height of the second movable seat 17 by adjusting the rotation of the motor 34, and then adjust the height of the X-ray generator A1; adjust the height of the fourth movable seat 20 by adjusting the rotation of the motor 33, and then adjust the height of the X-ray receiver A2. When using the X-ray generator A1 and the X-ray receiver A2 for radiography, it should always be ensured that the X-ray generator A1 and the X-ray receiver A2 move synchronously and are arranged face to face; when using the X-ray generator B6 and the X-ray receiver B7 for radiography, only need to adjust the X-ray generator B6 to the appropriate position and move it according to the preset path and preset speed. Since the X-ray receiver B7 is located on the workpiece carrier 4, as long as the workpiece is not larger than the effective detection surface of the X-ray receiver B7, the X-ray receiver B7 can always display the radiograph of the corresponding part.

[0076] Next, several methods for defect assessment of aluminum alloy castings will be described separately.

[0077] A method for defect assessment of aluminum alloy castings, used for the transverse part of an aluminum alloy plate-shaped casting 50 ( Figure 7To evaluate the defects in the area between the middle dashed lines 51, the width of this horizontal part is less than the effective width of a single X-ray penetration of the X-ray generator B 6. When performing X-ray penetration on this horizontal part, it only needs to move the X-ray generator B 6 horizontally once to complete the detection. The specific steps are as follows:

[0078] Step 1: Obtain the X-ray penetration image of the horizontal part of the workpiece with the aid of the automatic detection equipment in this embodiment. The detailed steps of this step include:

[0079] Step 11: Obtain the three-dimensional model of the workpiece (in this method, the aluminum alloy plate-shaped casting 50 is simply referred to as the workpiece), and establish a three-dimensional model coordinate system. (Except for errors, the size and contour of the three-dimensional model are exactly the same as the actual product).

[0080] Step 12: Obtain the workpiece coordinate system of the workpiece in the detection state after being in place (see Figure 7 ), and calculate the conversion relationship between the workpiece coordinate system and the three-dimensional model coordinate system. In this step, the approximate coordinate system of the workpiece plane established with the horizontal plane where the highest point of the top wall of the aluminum alloy casting is located is used as the workpiece coordinate system, that is, the upper surface of the workpiece is regarded as a horizontal plane.

[0081] Step 13: Select the model part that needs to be subjected to X-ray detection in the three-dimensional model of the workpiece, that is, select Figure 7 the area between the two dashed lines 51 in

[0082] Step 14: Combine the selected model part coordinates and the obtained conversion relationship to obtain the actual part coordinates on the workpiece that need to be subjected to X-ray detection. Since the approximate coordinate system of the workpiece plane is used as the workpiece coordinate system, the actual part coordinates finally obtained in this step "are equivalent to" the coordinates of a certain point mapped on the horizontal plane where the highest point of the top wall of the aluminum alloy casting is located (that is, the plane coordinates of the actual part on the workpiece that needs to be subjected to X-ray detection). In this case, there is only a slight difference in height between the actual part coordinates and the actual part plane coordinates, and this height difference will not affect the detection path and penetration effect in the present invention. Since the penetration path in this method is relatively simple, it only needs to know the penetration start point coordinates P(X1, Y) and the end point coordinates Q(X2, Y) corresponding to the actual penetration part.

[0083] Step 15: Control the X-ray source of the automatic detection equipment to move to the target detection position, and control the detector of the automatic detection equipment to move to the target receiving position. Substantially, move the X-ray generator B 6 directly above the penetration start point coordinates P(X1, Y). Since the X-ray receiver B7 in this method can completely cover the penetration area, it is default that the detector (X-ray receiver B7) is always in the target receiving position without moving. The state at this time is referred to Figure 6 as shown

[0084] Step 16, perform the X-ray radiography process, that is, control the X-ray generator B6 to move horizontally from the starting point of radiography to the ending coordinate Q(X2, Y) of radiography, so as to obtain the radiography image of the transverse part ( Figure 7 the area between the dotted lines 51 in the figure), and then store the X-ray radiography image into the computer system;

[0085] Step 2, measure the height h1 between the fixed plane and the upper surface of the workpiece through the fourth distance sensor, measure the height h2 between the fixed plane and the lower surface of the workpiece through the fifth distance sensor, measure the height h3 between the fixed plane and the horizontal plane where the detector window is located through the sixth distance sensor, and measure the height h4 between the detector window and the upper surface of the workpiece (substantially the upper surface of the radiographed part, the same below) through the seventh distance sensor; and calculate the thickness H of the radiographed part according to formula (Ⅲ);

[0086] H = h2 - h1…………………(Ⅲ)

[0087] This step is automatically measured by the corresponding sensor at the starting moment of radiography, and the data is fed back to the computer control system, and the computer control system calculates the thickness H of the radiographed part;

[0088] Step 3, calculate the magnification M of the obtained X-ray radiography image relative to the actual radiographed part according to formula (Ⅳ);

[0089] M = 1 + (h3 - h2) / h4…………………(Ⅳ)

[0090] Step 4, perform a reduction process on the obtained X-ray radiography image according to the obtained magnification M to obtain a reduced image;

[0091] Step 5, extract the defects and their characteristic parameters on the obtained reduced image by means of image feature extraction software, classify the extracted defects in combination with the obtained thickness H of the radiographed part, and compare them with the defects on the standard image, and output the defect evaluation result according to the comparison result; the standard image refers to the defect evaluation image in the aluminum alloy casting defect evaluation standard.

[0092] An aluminum alloy casting defect evaluation method is used to evaluate the defects in the longitudinal part ( Figure 8 the area between the dotted line 53 and the dotted line 55 in the figure) of the aluminum alloy plate-shaped casting 37. The width of this longitudinal part is slightly smaller than the sum of the effective widths of two radiographies of the X-ray generator B6. When radiographing this longitudinal part, it is necessary to rotate the X-ray generator B6 multiple times to complete the detection. The specific steps include:

[0093] Step 1, obtain the longitudinal part of the workpiece (aluminum alloy plate-shaped casting 37) by means of the automatic detection equipment in this embodiment ( Figure 8The X-ray radiograph of the area between the middle dashed line 53 and the dashed line 55); The detailed steps of this step include:

[0094] Step 11, obtain the three-dimensional model of the workpiece (except for errors, the dimensions and contours of the three-dimensional model are exactly the same as the actual product), and establish a three-dimensional model coordinate system;

[0095] Step 12, obtain the workpiece coordinate system of the workpiece in the detection state after being in place (see Figure 8 ), and calculate the transformation relationship between the workpiece coordinate system and the three-dimensional model coordinate system;

[0096] Step 13, select the model part of the workpiece that needs to be X-ray detected in the three-dimensional model of the workpiece, that is, select Figure 8 the area between the middle dashed line 53 and the dashed line 55;

[0097] Step 14, combine the coordinates of the selected model part and the obtained transformation relationship to obtain the actual part coordinates of the workpiece that need to be X-ray detected; Since the radiographic path in this method is a multi-rotation path, the radiographic starting point coordinates in the first rotation process can be set as F(X1, Y1), and the starting point coordinates in the last rotation process can be set as I(X1, Y1);

[0098] Step 15, control the X-ray source (X-ray generator B 6) of the automatic detection device to move to the target detection position, and control the detector of the automatic detection device to move to the target receiving position; Substantially, first move the X-ray generator B 6 to directly above the radiographic starting point coordinates F(X1, Y1). Since the X-ray receiver B7 can completely cover the radiographic area in this method, it is default that the detector (X-ray receiver B7) is always in the target receiving position without moving;

[0099] Step 16, perform the X-ray radiography process, and its radiographic path is: first control the detection center of the X-ray generator B 6 (i.e., the window center of the X-ray generator B 6) to rotate clockwise from the coordinate F(X1, Y1) to the coordinate G(X1, Y1), then control the detection center of the X-ray generator B 6 to rotate counterclockwise from the coordinate G(X1, Y1) to K(X1, Y1), then control the detection center of the X-ray generator B 6 to move to the starting point coordinate I(X1, Y1), then control the detection center of the X-ray generator B 6 to rotate clockwise from the coordinate (X1, Y1) to J(X1, Y1), and then control the detection center of the X-ray generator B 6 to rotate clockwise from the coordinate (J(X1, Y1) to I(X1, Y1). In this way, by radiographing two arc-shaped areas, the longitudinal part can be completely obtained ( Figure 8The fluoroscopic images of the area between the dotted line 53 and the dotted line 55 are obtained. Each time of fluoroscopy, the X-ray fluoroscopic image is stored in the computer system. In this step, two fluoroscopic images will be obtained finally. The area between the dotted line 53 and the dotted line 52 corresponds to the first fluoroscopic image, and the area between the dotted line 54 and the dotted line 54 corresponds to the second fluoroscopic image.

[0100] Step 17, if there are other parts on the workpiece that need to be defect-evaluated, steps 13 - 16 can be referred to, and the remaining parts of the workpiece that need to be X-ray detected are fluoroscoped.

[0101] Step 2, during each fluoroscopy process, the height h1 between the fixed plane and the upper surface of the workpiece is measured by the fourth distance sensor, the height h2 between the fixed plane and the lower surface of the workpiece is measured by the fifth distance sensor, the height h3 between the fixed plane and the horizontal plane where the detector window is located is measured by the sixth distance sensor, and the height h4 between the detector window and the upper surface of the workpiece is measured by the seventh distance sensor. And the thickness H of the fluoroscoped part is calculated according to formula (Ⅲ).

[0102] H = h2 - h1 ………………… (Ⅲ)

[0103] This step is automatically measured by the corresponding sensor at the start moment of fluoroscopy, and the data is fed back to the computer control system, and the computer control system calculates the thickness H of the fluoroscoped part.

[0104] Step 3, calculate the magnification M of the obtained X-ray fluoroscopic image relative to the actual fluoroscoped part according to formula (Ⅳ).

[0105] M = 1 + (h3 - h2) / h4 ………………… (Ⅳ)

[0106] Step 4, according to the obtained magnification M, the obtained X-ray fluoroscopic image is reduced to obtain a reduced image.

[0107] Step 5, with the help of image feature extraction software, the defects and their characteristic parameters on the obtained reduced image are extracted, and the extracted defects are classified in combination with the obtained thickness H of the fluoroscoped part, and compared with the defects on the standard image, and the defect evaluation result is output according to the comparison result.

[0108] A method for evaluating defects of aluminum alloy castings is used to evaluate the defects of the vertical part ( Figure 9 the area where the groove 39 is located) of the cylindrical aluminum alloy casting 36. The width of this part is less than the effective width of a single fluoroscopy of the X-ray generator A1. When fluoroscoping this vertical part, it only needs to move the X-ray generator A1 once vertically at the groove 39 to complete the detection. The specific steps include:

[0109] Step 1: Obtain the X-ray radiograph of the vertical part of the workpiece with the aid of the automatic detection device in this embodiment. The detailed steps of this step are as follows:

[0110] Step 11: Obtain the three-dimensional model of the workpiece (cylindrical aluminum alloy casting 36) (except for errors, the dimensions and contours of the three-dimensional model are exactly the same as the actual product), and establish a three-dimensional model coordinate system.

[0111] Step 12: Obtain the workpiece coordinate system of the workpiece in the detection state after being in place (see Figure 9 ), and calculate the conversion relationship between the workpiece coordinate system and the three-dimensional model coordinate system. Since it is a cylindrical aluminum alloy casting placed vertically, in this step, the workpiece plane coordinate system established with the top wall of the aluminum alloy casting is used as the workpiece coordinate system.

[0112] Step 13: Select the model part that needs to be X-ray detected in the three-dimensional model of the workpiece, that is, select Figure 9 the area where the groove 39 is located.

[0113] Step 14: Combine the coordinates of the selected model part and the obtained conversion relationship to obtain the actual part coordinates on the workpiece that need to be X-ray detected. Since the workpiece plane coordinate system is established with the top wall of the aluminum alloy casting in Step 12, what is finally obtained in this step is Figure 9 the plane coordinates R(X1, Y1) of the top of the groove 39 in

[0114] Step 15: Control the X-ray source of the automatic detection device to move to the target detection position, and control the detector of the automatic detection device to move to the target receiving position. Substantially, move the X-ray generator A1 to the left of the plane coordinates R(X1, Y1) and lower it to the limit position, and move the X-ray receiver A2 to the right of the plane coordinates R(X1, Y1) and lower it to the limit position. The state at this time is referred to Figure 5 as shown

[0115] Step 16: After Step 15 is completed, perform the X-ray radiography process, that is, control the X-ray generator A1 and the X-ray receiver A2 to rise synchronously at a preset speed, so that the radiograph of the vertical part of the area where the groove 39 is located can be obtained (that is, perform full radiography along the axial direction of the workpiece at the plane coordinates of the area where the groove 39 is located and obtain the radiograph), and then store the X-ray radiograph in the computer system.

[0116] Step 2: Obtain the distance S1 from the X-ray source (X-ray generator A1) of the automatic detection device to the surface of the irradiated part (here it refers to the vertical distance between the window of the X-ray generator A1 and the inner wall of the irradiated part), obtain the distance S2 from the detector window of the automatic detection device to the back of the irradiated part (here it refers to the vertical distance between the window of the X-ray receiver A2 and the outer wall of the irradiated part), and obtain the thickness H of the irradiated part; This step can be carried out synchronously with step 16;

[0117] Step 3: Calculate the magnification M of the obtained X-ray radiograph relative to the actual irradiated part according to formula (Ⅰ);

[0118] M = 1 + S2 / S1…………………(Ⅰ)

[0119] Step 4: According to the obtained magnification M, perform a reduction process on the obtained X-ray radiograph to obtain a reduced image;

[0120] Step 5: With the help of image feature extraction software, extract the defects and their characteristic parameters on the obtained reduced image, classify the extracted defects in combination with the obtained thickness H of the irradiated part, compare them with the defects on the standard image, and output the defect evaluation result according to the comparison result.

[0121] It should be noted that the obtained X-ray radiograph described in the present invention refers to a single radiograph, and the reduction process is also carried out for each image.

[0122] Adopting the solution of the present invention, the obtained radiograph is the same as the actual size specification of the irradiated part after reduction processing, which is convenient for comparison with the defect evaluation requirements in the aluminum alloy casting defect evaluation standard; The present invention is an intelligent evaluation method for defect grade evaluation based on GB / T 11346 of the national standard. With a recognized standard as the basis, the obtained defect evaluation result has good accuracy and high credibility; Adopting the solution of the present invention, it is possible to quickly and specifically evaluate the defects of the local part of the aluminum alloy casting, especially to accurately and quickly evaluate the defects of the local part of plate-shaped castings and cylindrical castings; Adopting the solution of the present invention, there is no need to use expensive high-precision small robots to be arranged in the detection area to control the movement of the X-ray generator and the X-ray receiver to the target position. Only by using a specific position adjustment mechanism and a specific detection path can the local part of the aluminum alloy casting be accurately radiographed. The detection cost is low, the control process is simple, and the control difficulty is small. It is especially suitable for defect evaluation of batch aluminum alloy castings.

Claims

1. A method for evaluating defects of aluminum alloy castings, characterized in that the steps Including: Step 1: Obtain the X-ray radiograph of the workpiece by means of an automatic detection device; Step 2: Obtain the thickness H of the radiographed part; Step 3: Obtain the magnification M of the X-ray radiograph relative to the actual radiographed part; Step 4: According to the obtained magnification M, reduce the obtained X-ray radiograph to obtain a reduced image; Step 5: Use image feature extraction software to extract the defects and their characteristic parameters on the obtained reduced image, classify the extracted defects in combination with the obtained thickness H of the radiographed part, compare them with the defects on the standard image, and output the defect assessment result according to the comparison result; the standard image refers to the defect assessment image in the aluminum alloy casting defect assessment standard; The automatic detection device includes an X-ray generator and an X-ray receiver arranged in the shielding room (3). The X-ray receiver converts the received signal into an image signal and displays it through a display terminal; A rotatable workpiece carrier (4) is arranged in the shielding room (3). The workpiece carrier (4) and its rotating mechanism are connected to a driving mechanism. The driving mechanism drives the workpiece carrier (4) and its rotating mechanism to move along the track (5). The track (5) extends from inside the shielding room (3) to near the automatic loading and unloading system; the X-ray generator is arranged on a position adjusting mechanism, and the position adjusting mechanism is installed on the top inside the shielding room (3); The rotating mechanism, the driving mechanism, the automatic feeding system, and the position adjusting mechanism are respectively connected to a computer control system. A program capable of running on a processing module is stored in the storage module of the computer control system. When the processing module executes the program, it can at least implement the following functions / steps: Control the workpiece carrier (4) and its rotating mechanism to move along the track (5) to a preset position; Control the workpiece carrier (4) to rotate at a preset angle; Control the automatic loading and unloading system to transfer the workpiece onto the workpiece carrier (4), and control the automatic loading and unloading system to remove the workpiece from the workpiece carrier (4); Control the X-ray generator to move to the target detection position and rotate at a preset speed; The position adjusting mechanism includes a rotating shaft (10) vertically installed on the top of the shielding room (3). The upper end of the rotating shaft (10) is connected to a motor (11), and the lower end of the rotating shaft (10) is connected to the middle of a horizontally arranged cross beam (12); two two-dimensional moving mechanisms are arranged on the cross beam (12). An X-ray generator A (1) is installed on the two-dimensional moving mechanism A, and an X-ray receiver A (2) is installed on the two-dimensional moving mechanism B. By controlling the two-dimensional moving mechanism, the X-ray generator A (1) and the X-ray receiver A (2) can be adjusted to the state of the same height and facing each other. The window orientation of the X-ray receiver A (2) is horizontal. By controlling the rotation of the motor (11), the X-ray generator A (1) and the X-ray receiver A (2) can be driven to rotate synchronously; The two-dimensional moving mechanism A includes a first horizontal lead screw (13) and a first vertical lead screw (14). A first movable seat (22) is engaged with the first horizontal lead screw (13). The first vertical lead screw (14) is connected to the first movable seat (22). A second movable seat (17) is engaged with the first vertical lead screw (14). A first link rod (18) arranged vertically is provided on the second movable seat (17). The X-ray generator A (1) is installed at the lower part of the first link rod (18). The two-dimensional moving mechanism B includes a second horizontal lead screw (15) and a second vertical lead screw (16). A third movable seat (19) is engaged with the second horizontal lead screw (15). The second vertical lead screw (16) is connected to the third movable seat (19). A fourth movable seat (20) is engaged with the second vertical lead screw (16). A second link rod (21) arranged vertically is provided on the fourth movable seat (20). The X-ray receiver A (2) is installed at the lower part of the second link rod (21). The center of the X-ray generator A (1), the center of the X-ray receiver A (2), the axis of the first vertical lead screw (14), the axis of the second vertical lead screw (16), and the axis of the rotating shaft (10) are located in the same vertical plane; A X-ray generator B (6) is further provided at the lower part of the first link rod (18). The window of the X-ray generator B (6) faces vertically downward. An X-ray receiver B (7) is provided on the workpiece bearing table (4). The diameter of the X-ray receiver B (7) is larger than the length of the workpiece. An acrylic plate and / or a foam pad for placing the workpiece are provided on the surface of the X-ray receiver B (7); The workpiece bearing table (4) is circular, and the workpiece bearing table (4) and the rotating shaft (10) are coaxially arranged.

2. The method for evaluating the defects of aluminum alloy castings according to claim 1, wherein: In step 2, For a workpiece placed vertically, the distance S1 from the X-ray source to the front of the penetrated part is measured by a first distance sensor installed near the X-ray source of the automatic detection equipment. The distance S2 from the detector window to the back of the penetrated part is measured by a second distance sensor installed near the detector of the automatic detection equipment. The distance L between the X-ray source and the detector window is measured by a third distance sensor installed near the X-ray source of the automatic detection equipment; and the thickness H of the penetrated part is calculated according to formula (Ⅱ); H = L - S1 - S2 ………………… (Ⅱ) In step 3, the magnification factor M of the X-ray penetrated image relative to the actual penetrated part is calculated according to formula (Ⅰ); M = 1 + S2 / S1 ………………… (Ⅰ) For a horizontally placed workpiece, the height h1 between the fixed plane and the upper surface of the workpiece is measured by the fourth distance sensor installed on the automatic detection device, the height h2 between the fixed plane and the lower surface of the workpiece is measured by the fifth distance sensor installed on the automatic detection device, the height h3 between the fixed plane and the horizontal plane where the detector window is located is measured by the sixth distance sensor installed on the automatic detection device, and the height h4 between the detector window and the upper surface of the workpiece is measured by the seventh distance sensor near the detector installed on the automatic detection device; and the thickness H of the radiographed part is calculated according to Equation (Ⅲ). H = h2 - h1…………………(Ⅲ) In Step 3, the magnification M of the X-ray radiographed image relative to the actual radiographed part is calculated according to Equation (Ⅳ), M = 1 + (h3 - h2) / h4…………………(Ⅳ).

3. The method for evaluating defects of aluminum alloy castings according to claim 2, wherein, The steps of obtaining the X-ray radiographed image in Step 1 include:[[]] Step 11, obtaining the three-dimensional model of the workpiece and establishing a three-dimensional model coordinate system; Step 12, obtaining the workpiece coordinate system of the workpiece in the detection state after being in place and calculating the conversion relationship between the workpiece coordinate system and the three-dimensional model coordinate system; Step 13, selecting the model part that needs to be subjected to X-ray detection in the three-dimensional model of the workpiece; Step 14, obtaining the actual part coordinates on the workpiece that need to be subjected to X-ray detection by combining the selected model part coordinates and the obtained conversion relationship; Step 15, controlling the X-ray source of the automatic detection device to move to the target detection position and controlling the detector of the automatic detection device to move to the target receiving position; Step 16, performing the X-ray radiography process according to the preset path and storing the X-ray radiographed image into the computer system; Step 17, performing radiography on the remaining parts of the workpiece that need to be subjected to X-ray detection according to Steps 13 - 16.

4. The method for evaluating defects of aluminum alloy castings according to claim 3, characterized in that: For a cylindrical aluminum alloy casting, the workpiece plane coordinate system established with the top wall or bottom wall of the aluminum alloy casting is used as the workpiece coordinate system; After selecting the model part that needs to be subjected to X-ray detection, the actual part plane coordinates on the workpiece that need to be subjected to X-ray detection are obtained by combining the corresponding coordinates of the selected model part and the obtained conversion relationship; when performing the X-ray radiography process, all radiography is performed along the axial direction of the workpiece at the actual part plane coordinates.

5. The method for evaluating defects of aluminum alloy castings according to claim 3, wherein: For a plate-shaped aluminum alloy casting, the workpiece plane approximate coordinate system established with the horizontal plane where the highest point of the top wall of the aluminum alloy casting is located is used as the workpiece coordinate system; After selecting the model part that needs to be subjected to X-ray detection, the actual part plane coordinates on the workpiece that need to be subjected to X-ray detection are obtained by combining the corresponding coordinates of the selected model part and the obtained conversion relationship.

6. The method for evaluating defects of aluminum alloy castings according to claim 3, characterized in that: The three-dimensional model of the workpiece is divided into several standard areas, and each standard area corresponds to the effective detection area of a single detection.

7. The method for evaluating defects of aluminum alloy castings according to claim 6, characterized in that: For the horizontal part that needs to be defect-evaluated on the plate-shaped aluminum alloy casting, after controlling the X-ray generator B(6) to move to the detection starting point, control the X-ray generator B(6) to move horizontally at a preset speed until the radiography is completed.

8. The method for evaluating defects of aluminum alloy castings according to claim 6, characterized in that: For the longitudinal part of the plate-shaped aluminum alloy casting that needs to be defect-evaluated, after controlling the X-ray generator B (6) to move to the detection starting point, control the X-ray generator B (6) to rotate at a preset speed until the radiography is completed, and the rotation center is located on the extension line of the rotating shaft (10); during one or more rotations of the X-ray generator B (6), the effective radiography area of the X-ray generator B (6) completely covers the longitudinal part that needs to be defect-evaluated.

9. The method for evaluating defects of aluminum alloy castings according to claim 6, characterized in that: For the vertical part of the cylindrical aluminum alloy casting that needs to be defect-evaluated, after controlling the X-ray generator A (1) to move to the detection starting point, control the X-ray generator A (1) to move vertically at a preset speed until the radiography is completed.

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