A non-contact self-alignment clamping system and method for a gate valve blank

Abstract

The application discloses a kind of gate valve blank non-contact self-aligning clamping system and self-aligning clamping method, system includes the robot body with robot gripper device, 3D vision system, control system, feeding device, robot gripper device is used to grab and move the gate valve blank to be clamped, 3D vision system is used to carry out three-dimensional scanning to gate valve blank, control system is used to generate 3D point cloud solid model, and obtains the center point pose value of pre-stored standard gate valve, and it is compared with current blank gate valve center point pose value, obtains pose offset value relative to robot gripping tool coordinate system, and it is sent to robot, and robot is according to pose offset value and is clamped to the gate valve blank that it grabs and is aligned, and after alignment, gate valve blank is moved to feeding device.The application is non-contact work by robot, alignment accuracy is high, clamping speed is fast, system is safe and stable, full automation, simultaneously can realize the data traceability management of gate valve clamping.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gate valve blank assembly, and particularly relates to a gate valve blank non-contact self-alignment clamping system and a self-alignment clamping method. BACKGROUND

[0002] With the rapid development of China's economy and the continuous improvement of industrial automation, China's equipment manufacturing industry is in the stage of transformation and upgrading, at the same time, the state's investment in the fields of oil and gas, petrochemical, environmental protection, electric power, metallurgy and other fields is in a state of continuous growth, and the overall size of the valve market will maintain a relatively fast growth rate. The rapid growth of market demand for valves further puts forward faster and higher requirements for valve processing and production.

[0003] At present, the gate valve processing machine tool on the market is an old type turning-milling-grinding machine, which uses a traditional processing technology. The gate valve blank clamping is the first process of gate valve processing and is one of the key processes. At present, there is no unified clamp for gate valve blank clamping, and the relatively complex alignment mechanism is currently operated by manual operation to achieve the purpose of alignment and clamping. The alignment mechanism uses a three-jaw or four-jaw self-centering method. Due to the use of casting process for the gate valve blank, the thermal expansion and contraction of the material during the casting process will cause the deformation of the gate valve blank, thereby destroying the positioning reference of the blank. In addition, the blank material and casting process used by each manufacturer are different, making the blank more irregular. Due to the irregularity of the flange inner ring of the gate valve blank, when the three-jaw or four-jaw self-centering method is used, the valve blank alignment adjustment becomes very difficult. The three-point or four-point positioning on the irregular circle has a relatively small sampling and a relatively poor centering accuracy. In addition, due to the existence of the gate valve outer circle end face pouring runner, it will also become excessive adjustment. For a relatively regular gate valve blank, the adjustment can be completed for 2 to 3 times, but for a severely deformed gate valve blank, the single three-jaw or four-jaw self-centering method will not be able to complete the alignment function. As described above, such an operation method also has the following disadvantages:

[0004] 1) The manual clamping efficiency is not high. If the manual operation is completely used to adjust the alignment, sometimes 5 to 6 times of back and forth adjustment of an irregular blank is needed to complete the adjustment;

[0005] 2) The manual clamping has subjective and objective factors, and the clamping accuracy is not high and the consistency is poor;

[0006] 3) There is a great safety hazard in manual clamping;

[0007] 4) It is not easy to realize the data traceability management of the gate valve clamping by manual clamping;

[0008] 5) The manual clamping cannot realize the function expansion of the clamping and cannot provide more intelligent processing service for the subsequent process.

[0009] Therefore, in order to solve the above-mentioned deficiencies, there is now a need for a non-contact self-alignment clamping system and method for gate valve blanks. SUMMARY

[0010] In order to overcome the deficiencies of the prior art, the present application provides a non-contact self-alignment clamping system and method for gate valve blanks, which can intelligently complete high-precision operations under the premise of safety and reliability, and the system is simple to operate. The technical solution is as follows:

[0011] On the one hand, the present application provides a non-contact self-alignment clamping system for gate valve blanks, comprising:

[0012] A robot body having a robot gripper device for grabbing and moving the gate valve blank to be clamped;

[0013] A 3D vision system for three-dimensional scanning of the gate valve blank grabbed by the robot gripper device to obtain three-dimensional point cloud data;

[0014] A control system in communication with the 3D vision system and the robot body, the control system being configured to generate a three-dimensional point cloud model based on the three-dimensional point cloud data scanned by the 3D vision system, and to analyze the three-dimensional point cloud model to obtain the axis of different sides of the gate valve blank, and to calculate the current clamping center point coordinates and the current Euler angle value of the gate valve blank based on the axis;

[0015] The control system acquires the standard clamping center point coordinates and the standard Euler angle value of the pre-stored standard product, and compares them with the current clamping center point coordinates and the current Euler angle value of the gate valve blank to obtain the pose offset value, and sends it to the robot body; the robot body adjusts the clamping position of the gate valve blank grabbed by it according to the pose offset value, and moves the gate valve blank after position adjustment to the feeding device;

[0016] A feeding device having a hydraulic clamping device provided thereon, the hydraulic clamping device being configured to clamp the gate valve blank placed on the feeding device.

[0017] Further, the non-contact self-alignment clamping system for gate valve blanks further comprises a material taking device for storing gate valve blanks, the material taking device being provided with at least one hanger and at least one material taking position, under the driving of a driving mechanism, the hanger drives different gate valve blanks to reach the material taking position in turn.

[0018] Further, the material taking position of the material taking device is provided with a centralizing device, the centralizing device being configured to coarsely position the gate valve blank reaching the material taking position.

[0019] Further, the 3D vision system scans the grabbed gate valve blank in five view faces to obtain five view Figure Three dimensional point cloud data, and the five view Figure Three dimensional point cloud data is used to generate a three-dimensional point cloud solid model.

[0020] Further, the control system obtains the axes of two or more sides of the gate valve blank in the three-dimensional point cloud solid model data by using a digital mapping method.

[0021] In particular, after the robot gripper device grabs the gate valve blank, the gate valve blank is coarsely positioned with the guide diameter as the first reference surface, so that the gate valve blank and the standard product are both established in the same positioning manner; then the three orthogonal axes of the gate valve blank are found in the feature point line surface in the three-dimensional point cloud solid model of the gate valve blank as the reference, and the intersection of the three orthogonal axes is taken as the current clamping center point.

[0022] Further, the non-contact self-alignment clamping system for the gate valve blank further comprises a hydraulic station, and the hydraulic clamping device is in communication with the hydraulic station.

[0023] In another aspect, the present application provides a non-contact self-alignment clamping method for a gate valve blank, comprising the following steps:

[0024] S1, the robot gripper of the robot body moves to the taking position of the taking device, and after extending a certain distance along the guide diameter of the gate valve blank, the gate valve blank is locked by hydraulic pressure on the robot gripper;

[0025] S2, the robot gripper drives the gate valve blank to move to the 3D vision system, and the 3D vision system performs three-dimensional scanning on the gate valve blank to obtain three-dimensional point cloud data;

[0026] S3, the control system generates a three-dimensional point cloud solid model according to the three-dimensional point cloud data, analyzes the three-dimensional point cloud solid model to obtain the axes of different sides of the gate valve blank, and calculates the current clamping center point coordinates and the current Euler angle value of the gate valve blank according to the axes;

[0027] S4, the control system obtains the standard clamping center point coordinates and the standard Euler angle value of the pre-stored standard product, and compares them with the current clamping center point coordinates and the current Euler angle value of the gate valve blank to obtain the pose offset value;

[0028] S5, the robot body aligns the clamping position of the gate valve blank according to the pose offset value, and moves the gate valve blank after the clamping position is aligned to the feeding device;

[0029] S6, the hydraulic clamping device on the feeding device clamps the gate valve blank placed on the feeding device.

[0030] Further, in step S1, the robot gripper extends along the guide diameter of the gate valve blank to a certain distance, so that the first center point of the gate valve blank coincides with the center point of the tool coordinate system of the robot gripper, and the gate valve blank is coarsely positioned with the guide diameter as the first reference surface, so that the gate valve blank and the standard product are both established in a constraint relationship in the same positioning manner.

[0031] In step S3, the three orthogonal axes of the gate valve blank are found in the feature point line surface in the three-dimensional point cloud solid model as a reference, and the intersection point of the three orthogonal axes is taken as the current clamping center point.

[0032] Further, in step S4, the pose offset value includes a clamping center point coordinate offset value and an Euler angle offset value, wherein the clamping center point coordinate offset value is the difference between the standard clamping center point coordinate and the current clamping center point coordinate, and the Euler angle offset value is the difference between the standard Euler angle value and the current Euler angle value.

[0033] The technical scheme provided by the present application has the following beneficial effects:

[0034] a. The robot is used for full-process non-contact operation, the alignment accuracy is high, the clamping speed is fast, the system is safe and stable, and the degree of automation is high;

[0035] b. The 3D model data of the gate valve blank is obtained through the vision system, accurate scanning is performed, the system operation speed is fast, and data traceability management of the gate valve clamping can be realized;

[0036] c. Compared with manual operation, not only the clamping function can be expanded to provide intelligent processing services for subsequent processes, but also the labor cost is saved. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Figure 1 is a structural schematic diagram of the non-contact self-alignment clamping system for the gate valve blank provided by the embodiment of the present application;

[0039] Figure 2 is a structural schematic diagram of the gate valve blank workpiece provided by the embodiment of the present application;

[0040] Figure 3is a schematic view of a gate valve blank workpiece ABF axis in a non-contact self-alignment clamping system for a gate valve blank provided by an embodiment of the present application;

[0041] Figure 4 is a work flow chart for finding a center point coordinate in a non-contact self-alignment clamping system for a gate valve blank provided by an embodiment of the present application;

[0042] Figure 5 is a step flow chart of a visual alignment method in a non-contact self-alignment clamping system for a gate valve blank provided by an embodiment of the present application.

[0043] In the drawings, reference numerals include: 1 - hanger, 2 - gate valve blank, 3 - taking position, 4 - centralizing device, 5 - robot gripper device, 6 - robot body, 7 - 3D vision system, 8 - control system, 9 - feeding device, 91 - hydraulic clamping device, 11 - taking device, 13 - hydraulic station, 21 - guide diameter, 22 - first reference surface, 23 - wall thickness, 31 - left and right side end faces of U-shaped port, 32 - left and right flange inner end faces, 33 - left and right flange outer end faces, 34 - U-shaped port upper plane. DETAILED DESCRIPTION

[0044] In order to enable the person skilled in the art to better understand the present application scheme, more clearly understand the purpose, technical scheme and advantages of the present application, the technical scheme in the embodiments of the present application is described clearly and completely below in combination with specific embodiments and with reference to the drawings. It should be noted that the implementation mode not shown or described in the drawings is the form known to those skilled in the art. In addition, although this document can provide examples of parameters containing specific values, it should be understood that the parameters do not necessarily equal the corresponding values, but can be approximately equal to the corresponding values within an acceptable error tolerance or design constraint. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application. In addition, the terms "include" and "have" in the specification and claims of the present application, as well as any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, device, product or equipment containing a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0045] In one embodiment of the present application, a non-contact self-alignment clamping system for a gate valve blank is provided, as shown in Figure 1 The system includes a taking device 11, a robot body 6, a 3D vision system 7, a control system 8, a feeding device 9 and a hydraulic station 13.

[0046] The taking device 11 is used for storing the gate valve blank 2, and is provided with at least one hanger 1 and at least one taking position 3, wherein the hanger 1 drives different gate valve blanks 2 to reach the taking position 3 in turn under the drive of a driving mechanism, and the taking position 3 is further provided with a righting device 4 for roughly positioning the gate valve blank 2 reaching the taking position 3.

[0047] The robot body 6 is provided with a robot gripper device 5 for grabbing and moving the gate valve blank 2 to be clamped, and the 3D vision system 7 is used for scanning the gate valve blank 2 grabbed by the robot gripper device 5 to obtain three-dimensional point cloud data, and the control system 8 is in communication connection with the 3D vision system 7 and the robot body 6, and the control system 8 is used for processing the three-dimensional point cloud data and controlling the robot body 6 to adjust accordingly.

[0048] The feeding device 9 is provided with a hydraulic clamping device 91 for clamping the gate valve blank 2 placed on the feeding device 9, and the hydraulic station 13 is in communication with the hydraulic clamping device 91, and the hydraulic station 13 is used for providing power support for the hydraulic clamping device 91.

[0049] Specifically, the control system 8 sends a taking signal to the robot body 6, the robot body 6 moves to the taking position 3 after receiving the taking instruction, the robot gripper device 5 grabs the gate valve blank 2 roughly positioned by the righting device 4 and sends a taking completion signal to the control system 8, and the control system 8 sends a scanning instruction to the robot body 6 after receiving the completion signal, and the robot body 6 moves to the 3D vision system 7 after receiving the scanning instruction, and the 3D vision system 7 scans the grabbed gate valve blank 2 and sends the obtained three-dimensional point cloud data to the control system 8.

[0050] It should be noted that, as shown in Figure 2 When the robot gripper device 5 performs the grabbing action, it extends along the first reference surface 22 of the guide diameter 21 of the gate valve blank 2 by a certain distance, and then the robot gripper device 5 locks the gate valve blank 2 under the power support of the hydraulic station 13, so that the first positioning of the gate valve blank 2 is realized. In addition, the 3D vision system 7 can scan the 5 view surfaces (front view surface, rear view surface, left view surface, right view surface and upper view surface) of the gate valve blank 2 to obtain three-dimensional point cloud data of the 5 view surfaces.

[0051] The control system 8 generates a three-dimensional point cloud model according to the three-dimensional point cloud data splicing, analyzes the three-dimensional point cloud model, obtains the axis of different sides of the gate valve blank 2, and calculates the current clamping center point coordinates and the current Euler angle value of the gate valve blank 2 according to the axis. By obtaining the standard clamping center point coordinates and the standard Euler angle value of the pre-stored standard product, the control system 8 compares the current clamping center point coordinates and the current Euler angle value of the gate valve blank 2, obtains the pose offset value, and sends it to the robot body 6. The robot body 6 further adjusts the position of the gate valve blank 2 according to the pose offset value, and moves the gate valve blank 2 after position adjustment to the feeding device 9, thereby completing the non-contact self-positioning and clamping operation of the gate valve blank 2. It should be noted that the control system 8 obtains the axis ABF of the gate valve blank 2 in the three-dimensional point cloud data by using digital mapping, and verifies the machining allowance of each axis respectively. The minimum value of the variance or standard deviation of the distance to each axis surface is taken as the reference axis, so as to obtain the current clamping center point coordinates and the pose offset value with relatively high accuracy, thereby providing relatively accurate data support for subsequent positioning operation.

[0052] In one embodiment of the present application, a non-contact self-positioning and clamping system for a gate valve blank is provided, as shown in Figures 1-2 The system includes a robot body 6, a 3D vision camera system 7, a material taking device 11, a feeding device 9, a hydraulic station 13, and a PC control system 8.

[0053] The gate valve blank 2 is stored in a stereoscopic warehouse, the robot body 6 runs to a specific material taking position 3 in the stereoscopic warehouse, extends into the guide diameter 22 of the gate valve blank 2 through the robot gripper device 5, positions and then grabs the gate valve blank 2, after the grabbing is completed, the first rough positioning of the gate valve blank 2 is realized, then the robot body 6 moves to the 3D vision camera system 7, three-dimensional scanning is carried out, after five view surfaces (front, rear, left, right and upper view) are scanned respectively, three-dimensional point cloud data of five views is obtained, then after processing by the PC control system 8, a 3D point cloud stereoscopic model is spliced, so that the real physical object is one-to-one corresponding to the digital simulation, the 3D point cloud stereoscopic model of the gate valve blank 2 is analyzed by the PC control system 8, digital surveying and mapping is adopted, the axis ABF of different surfaces is found, the clamping center point coordinates and Euler angle values of the gate valve blank 2 are quickly and accurately found, by comparing with the clamping center point coordinates and Euler angle values of the standard product (the clamping center point coordinate pose of the standard product is the original pose of the Ot tool coordinate system established by the robot in advance), the actual pose offset value is calculated, then the pose offset value is transmitted to the robot body 6, after the pose offset value is obtained, the robot body 6 compensates and corrects through the motion control model of itself, the gate valve blank 2 is correctly placed into the clamping center point of the feeding device 9, so that unmanned automatic alignment is realized, after the alignment, the clamping function can be realized by operating the hydraulic clamping device, so that the one-time non-contact automatic alignment and clamping of the gate valve blank 2 are completed.

[0054] In one embodiment of the present application, a gate valve blank non-contact self-alignment and clamping system is provided, as shown in the accompanying drawings, the system comprises a robot body 6, a 3D vision camera system 7, a material taking device 11, a feeding device 9, a hydraulic station 13 and a PC control system 8, and there are six main plate blocks. Figures 1-2

[0055] The 3D vision camera system 7 is installed on a flat ground and is subjected to damping treatment. The robot body 6 is installed on a flat ground, so that the robot is firm and reliable. The material taking device 11 and the feeding device 9 are respectively fixedly installed on the left and right sides of the robot.

[0056] The connection between the plate blocks of the system is achieved by communication, the network architecture of the system components uses an industrial Ethernet bus, and the communication protocols respectively use the internationally common Profinet protocol and the Modbus TCP protocol.

[0057] ​The PC control system sends a picking signal to the robot body 6, the robot body 6 moves to the picking position 3 of the picking device 11, the gate valve blank of the picking position 3 is suspended in the picking position 3 through the rough positioning of the righting device 4, the robot body 6 further extends into the gate valve blank along the guide diameter 21 of the gate valve blank to the first reference surface 22 of the gate valve blank through the robot gripper device 5, and then the gate valve blank is locked by hydraulic pressure, so that the first positioning of the gate valve blank on the robot body 6 is realized. The rough positioning accuracy and consistency of the gate valve blank on the robot body 6 are effectively ensured by the righting device 4 and the robot gripper device 5.

[0058] After the picking of the robot body 6 is completed, a picking completion signal is sent to the PC control system 8, the PC control system 8 receives the picking completion signal, and then sends a 3D scanning motion instruction to the robot body 6, the robot body 6 then moves to the visual scanning device scanning position to perform scanning of five views (front, rear, left, right and upper views), after the scanning is completed, the PC control system 8 performs splicing and merging, after the splicing is completed, a relatively complete 3D point cloud stereoscopic model is obtained, and the PC control system 8 further performs digital mapping and sampling analysis on the 3D point cloud simulation model.

[0059] Then, three orthogonal axes (ABF) of the gate valve blank 2 and their intersection point, i.e. the center point coordinates, need to be found. After the robot gripper device 5 grabs the gate valve blank 2, the rough positioning of the gate valve blank 2 on the end of the robot body 6 is realized with the guide diameter as the first reference surface 22. For a standard product, a tool coordinate system Ot is also established on the end of the robot body 6 with the guide diameter 21 of the gate valve blank 2 as the first reference surface 22. The gate valve blank 2 and the standard product establish a constraint relationship in the same positioning manner. After the constraint is established, the three orthogonal axes (ABF) of the gate valve blank 2 can be found in the 3D point cloud model of the gate valve blank 2 from some feature points, lines and surfaces that can be used as references.

[0060] As shown in Figures 3-4 , the left and right end surfaces 31 of the U-shaped port of the gate valve blank 2 are used as references to find the axis A 1 perpendicular to the middle line of the upper end surface 34 of the U-shaped port 1 . Theoretically, the axis A 1 coincides with the axis A of the standard product workpiece, but due to the rough positioning of the gripper, the blank pose has swing and the blank itself has deformation errors, so there is deviation, so the axis A 2 is used as the first reference on the blank, and the middle line axis A 1and axis A 2 Between them, we can find a dividing axis A. 3 The dividing axis A 3 If the deviation value of the first reference A of the standard product is within the range, then we take the midpoint axis A as the reference. 3 For the first axis A of the blank we are looking for, if the axis A is the dividing line in the middle... 3 If the deviation is not within the first datum A of the standard product, then we take the maximum tolerance value of the first datum A of the standard product as the axis A of the blank, and then take axis A... 3 Give axis A 2 The deviation value is output to the machine tool, which is used to correct the error value of the flange end face to ensure the uniformity of the thickness of the two flange end faces during processing. After finding the blank axis A, the machining allowance of the two flange end faces is then verified. If the machining allowance is met, the axis A is aligned. If not, the above method is used again to find it.

[0061] Once axis A is found, then look for the second axis B. 1 The center points of the left and right flange outer end faces 33 of the gate valve blank 2 can be found. Connecting these points with a line will reveal the axis B. 1 At this time, the axis A of the blank is opposite to the axis B. 1 Not necessarily orthogonal, passing through axis A and axis B 1 Draw a line from the intersection of axis A and axis B perpendicular to axis B. 2 However, taking axis B as an example 2 The centerline axis is used to verify the machining allowance of the outer circle of the flange end face. If the machining allowance is sufficient, then the centerline axis B is... 2 This is the axis B we are looking for. If it does not meet the requirements, we will search for it again using the method described above.

[0062] Once axis B is found, find the third axis F. Find an axis parallel to the upper end face 34 of the U-shaped opening, passing through the center of axes A and B. This axis is axis F. 1 If this axis F 1 To satisfy the machining allowance for the thickness of the U-shaped opening, the axis F at this time... 1 This is the axis F we are looking for. If it does not meet the requirements, we will search for it again using the method described above.

[0063] After locating the three axes ABF of the gate valve blank 2, the intersection of the ABF axes is the clamping center point of the gate valve blank 2. Using this point as the origin and ABF as the three orthogonal axes ZXY, a coordinate system O1 for the clamping center point of the gate valve blank is established. The coordinates O1 of the gate valve blank center point are then compared with the coordinates Ot of the clamping center point of the standard product to obtain the actual position and Euler angle offset value, thereby realizing the automatic alignment function of the gate valve blank.

[0064] The robot body 6 obtains the offset pose data, compensates and corrects through the motion control model of the robot body 6, then superimposes the clamping center point O1 coordinate system of the gate valve blank on the center position O2 coordinate system of the clamping of the feeding device, and completes the alignment and placement. Then the gate valve blank is pressed by using the hydraulic device, and after being pressed, the robot body 6 is given a retreat instruction, and the robot body 6 retreats to the original waiting position 3, so that the one-time clamping process of the gate valve blank 3D scanning alignment is completed.

[0065] After the 3D point cloud simulation model is established, other functions of the digital mapping of the gate valve blank can be performed, the size of the wall thickness 23 of the gate valve blank is measured and mapped, the casting quality of the gate valve blank can be evaluated, which has important guiding significance for the casting of the gate valve blank, and real-time feedback can be given to the foundry to guide production; the size of the gate valve blank is measured and mapped, and the gate valve blank is provided with the rough milling gate riser starting point data and the cutting amount data, so that the self-adaptive intelligent processing mode of the rough milling process is realized.

[0066] In an embodiment of the present application, the present application further provides a visual alignment method. Figure 5 As shown in the figure, the steps of the visual alignment method are as follows:

[0067] (1) 3D camera calibration (obtaining camera intrinsic parameters, extrinsic parameters and distortion parameters);

[0068] In image measurement or machine vision applications, the calibration of camera parameters is a very critical link, and the accuracy of the calibration result and the stability of the algorithm directly affect the accuracy of the camera working result.

[0069] The camera calibration methods are: traditional camera calibration method, active vision camera calibration method, camera self-calibration method.

[0070] Camera intrinsic parameter calibration is generally calibrated by the factory, and we only need to calibrate the extrinsic parameters.

[0071] The purpose of calibration is to realize all the motion data and object position and attitude information in one coordinate system.

[0072] The robot clamps the standard part to move along Z with a fixed posture, and a set of profile data is generated every 2mm. Since the profile data only has X and Z, not Y, it is assumed that the Y of the first profile line is 0, the y coordinate of the second profile line is 2, and so on to obtain the profile scanning graph. The center of the circle is found in the scanned gray scale graph to obtain the feature point coordinates (x, y) of the standard part, and the z data is obtained according to the gray value. Thus, the feature point coordinates (x, y, z) in the profile coordinate system are obtained. These feature point coordinates in the profile coordinate system are subjected to affine transformation with the robot coordinate system coordinates to obtain the affine transformation matrix T. The T is the transfer matrix of the profile coordinate transformation to the world coordinate system coordinates. With T, the calibration is completed.

[0073] (2) The robot tool coordinate system (X 1 Y 1 Z 1 ) with the center point of the standard part clamped as the origin is established.

[0074] The constraint relationship between the standard part and the blank is that the robot gripper is grasped with the first reference A reference positioning, and after positioning, the constraint relationship with the first reference A as the reference is established between the two.

[0075] The center of the gripper coincides with the flange original tool center point of the sixth axis of the robot, and is offset from the Z axis of the flange tool coordinate system by a certain distance (the distance between the center point of the standard part and the center point of the flange), to establish the robot tool coordinate system (X 1 Y 1 Z 1 ) with the center point of the standard part clamped as the origin, that is, the Ot coordinate system.

[0076] (3) The robot pose value of the center point coordinate of the feeding device completely coinciding with the center point coordinate of the standard part is calibrated by using the robot and the standard tool;

[0077] The standard tool is placed on the feeding device, and after hydraulic locking, the center point pose of the standard tool coincides with the center point pose of the workpiece placed on the feeding device.

[0078] A cylindrical protruding correction workpiece is installed on the flange of the robot, the robot adjusts the pose to make the correction workpiece completely coincide with the disc-shaped recessed hole on the standard tool, and then the robot moves a certain distance along the tool coordinate system X 1 Y 1 Z 1 (After coincidence, the tool coordinate system X 1 Y 1 Z 1 distance difference with the standard tool Z direction, which can be calculated from the tool and correction workpiece drawing size), which is the robot pose value of the center point coordinate of the feeding device completely coinciding with the center point coordinate of the standard part, that is, the O2 coordinate system.

[0079] (4) Robot 5 scan position projection pose calibration;

[0080] Symmetrical center finding point, non-orthographic projection scanning can also find the center, but for asymmetric parts, non-orthographic projection scanning will cause the size to be distorted, affecting the accuracy of measurement. Therefore, to find the orthographic projection pose of the robot, a cube can be installed on the robot flange to correct the orthographic projection pose of the robot 5 scanning positions.

[0081] (5) Robot coordinates with camera scanning gate valve blank 5 view surface, generating three-dimensional point cloud data;

[0082] (6) Use PC control system to splice 5 view surface three-dimensional point cloud data into 3D point cloud solid model;

[0083] (7) Find three orthogonal axes (ABF) of the gate valve blank and their intersection point (the clamping center point of the valve blank);

[0084] (8) Establish the Cartesian rectangular coordinate system (X 2 Y 2 Z 2 ) with the clamping center point of the gate valve blank as the origin;

[0085] After finding the three orthogonal axes (ABF) and their center intersection point, a Cartesian rectangular coordinate system (X 2 Y 2 Z 2 ) with the intersection point as the origin can be established. This coordinate system is also the Cartesian rectangular coordinate system (X 2 Y 2 Z 2 ) with the clamping center point of the gate valve blank as the origin, which is the O1 coordinate system.

[0086] (9) Calculate the relative pose deviation value of the gate valve blank center point coordinate system and the robot tool coordinate system

[0087] X 2 Y 2 Z 2 coordinate system and X 1 Y 1 Z 1 coordinate system is determined, X 2 Y 2 Z 2 relative to X 1 Y 1 Z 1 pose deviation can be calculated according to the rotation matrix, and the XYZABC 6 data deviation values of the two tool coordinate systems can be calculated.

[0088] (10) Output the pose deviation value to the robot;

[0089] The PC control system transmits offset.X, offset.Y, offset.Z, offset.A, offset.B, offset.C to the robot through communication.

[0090] (11) The robot moves to the clamping position, and the relative position of the gate valve blank is offset according to the obtained relative tool coordinate system pose deviation value, so that the gate valve blank realizes automatic alignment.

[0091] In an embodiment of the present application, the present application also provides a non-contact self-alignment clamping method of a gate valve blank, comprising the following method:

[0092] S1, the robot gripper of the robot body moves to the material taking position of the material taking device, and after extending a certain distance along the guide diameter of the gate valve blank, the gate valve blank is locked by hydraulic pressure on the robot gripper;

[0093] S2, the robot gripper drives the gate valve blank to move to the 3D vision system, and the 3D vision system performs three-dimensional scanning on the gate valve blank to obtain three-dimensional point cloud data;

[0094] S3, the control system generates a three-dimensional point cloud solid model according to the three-dimensional point cloud data, analyzes the three-dimensional point cloud solid model to obtain the axis of different sides of the gate valve blank, and calculates the current clamping center point coordinates and current Euler angle value of the gate valve blank according to the axis;

[0095] S4, the control system obtains the standard clamping center point coordinates and standard Euler angle value of the pre-stored standard product, and compares them with the current clamping center point coordinates and current Euler angle value of the gate valve blank to obtain the pose offset value;

[0096] S5, the robot body aligns the clamping position of the gate valve blank according to the pose offset value, and moves the gate valve blank after position alignment to the material loading device;

[0097] S6, the hydraulic clamping device on the material loading device clamps the gate valve blank placed on the material loading device.

[0098] In the embodiment of the present application, first, in step S1, the robot gripper extends along the guide diameter of the gate valve blank to a certain distance, so that the clamping center point of the gate valve blank and the center point of the tool coordinate system Ot of the robot gripper establish a constraint relationship; second, in step S3, the control system obtains the axis ABF of different sides of the gate valve blank in the three-dimensional point cloud data by using digital mapping, and the current clamping center point coordinate of the gate valve blank is obtained by using the intersection point of the three orthogonal axes of ABF; third, in step S4, the pose offset value includes the clamping center point coordinate offset value and the Euler angle offset value, wherein the clamping center point coordinate offset value is the difference between the standard clamping center point coordinate and the current clamping center point coordinate, and the Euler angle offset value is the difference between the standard Euler angle value and the current Euler angle value.

[0099] The idea of the embodiment of the non-contact self-aligning clamping method of the gate valve blank is the same as the working process of the non-contact self-aligning clamping of the gate valve blank in the above embodiment, and the entire content of the above embodiment of the non-contact self-aligning clamping system of the gate valve blank is incorporated herein by reference.

[0100] Compared with the prior art, the present application has the following outstanding and beneficial technical effects. First, the structure is relatively simple, easy to implement modular operation, does not need to design a complex clamping mechanism, the production and manufacturing cycle is relatively short, and the maintenance is relatively simple and fast. Second, the clamping speed depends on the scanning speed and the alignment speed depends on the operation speed of the PC control system, the whole process is automatic and unmanned, the clamping speed is fast and stable, and the clamping efficiency is high. Third, the robot automatically grabs and releases the material, the machine vision 3D scans and measures, and the PC control system measures and calculates, the whole process is automatic operation, the alignment is convenient, the measurement is stable and reliable, the precision is high, and the whole clamping precision is also high. Fourth, the robot and vision are used to replace manual operation to realize non-contact alignment and clamping, which is safe, reliable and effective, saves labor cost, and can realize multi-species and multi-batch alignment and clamping of gate valve products with high flexibility. Most importantly, the present application has outstanding performance in visualization, data traceability, digitization and intelligence.

[0101] Through visual scanning imaging, the entire 3D model data of the gate valve blank can be established, the gate valve blank can be directly presented in the PC control system, and the required related size data such as the clamping center point coordinate, the blank wall thickness and the machining starting point data of the pouring riser can be obtained after measurement and analysis by the PC control system, and stored in the PC control system, so as to realize identity marking and provide intelligent data processing service for the next machining process.

[0102] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A non-contact self-aligning clamping system for gate valve blanks, characterized in that, include: The robot body (6) has a robot gripper device (5) for gripping and moving the gate valve blank (2) to be clamped. The 3D vision system (7) is used to perform three-dimensional scanning of the gate valve blank (2) gripped by the robot gripper device (5) to obtain three-dimensional point cloud model data, including scanning the front view, rear view, left view, right view and top view of the gripped gate valve blank (2) to obtain three-dimensional point cloud data of five view planes. The control system (8) is communicatively connected to the 3D vision system (7) and the robot body (6). The control system (8) is used to generate a three-dimensional point cloud model based on the three-dimensional point cloud data of the five view planes scanned by the 3D vision system (7), and to analyze the three-dimensional point cloud model to obtain the axis of different sides of the gate valve blank (2), and to obtain the current clamping center point coordinates and current Euler angle value of the gate valve blank (2) based on the axis. The control system (8) acquires the standard clamping center point coordinates and standard Euler angle values ​​of the pre-stored standard product, and compares them with the current clamping center point coordinates and current Euler angle values ​​of the gate valve blank (2) to obtain the pose offset value, and sends it to the robot body (6); the pose offset value includes the clamping center point coordinate offset value and the Euler angle offset value, wherein the clamping center point coordinate offset value is the coordinate difference between the standard clamping center point coordinates and the current clamping center point coordinates, and the Euler angle offset value is the difference between the standard Euler angle value and the current Euler angle value; the robot body (6) performs clamping position alignment on the gate valve blank (2) it has grasped according to the pose offset value, and transfers the aligned gate valve blank (2) to the loading device (9); The feeding device (9) is equipped with a hydraulic clamping device (91), which is connected to the hydraulic station (13). The hydraulic clamping device (91) is used to clamp the gate valve blank (2) placed on the feeding device (9). A material handling device (11) for storing gate valve blanks (2) is provided. The material handling device (11) is provided with at least one bracket (1) and at least one material handling position (3). Under the drive of the drive mechanism, the bracket (1) drives different gate valve blanks (2) to the material handling position (3) in sequence. A straightening device (4) is provided at the material handling position (3) of the material handling device (11). The straightening device (4) is used to perform coarse positioning on the gate valve blanks (2) that have arrived at the material handling position (3). The control system (8) uses digital mapping to obtain the axes of two or more sides of the gate valve blank (2) in the three-dimensional point cloud model. After the robot gripper device (5) grabs the gate valve blank (2), it uses the guide diameter of the gate valve blank as the first reference surface to perform coarse positioning on the gate valve blank (2), so that the gate valve blank (2) and the standard product establish a constraint relationship in the same positioning method. Then, in the three-dimensional point cloud model of the gate valve blank (2), the three orthogonal axes of the gate valve blank (2) are found in the feature points, lines and surfaces that serve as the reference, and the intersection of the three orthogonal axes is used as the current clamping center point.

2. A clamping method based on the non-contact self-aligning clamping system for gate valve blanks as described in claim 1, characterized in that, Including the following methods: S1. The robot gripper of the robot body moves to the material handling position of the material handling device, and after extending a certain distance along the guide diameter of the gate valve blank, the gate valve blank is hydraulically locked onto the robot gripper. S2. The robot gripper moves the gate valve blank to the 3D vision system, and the 3D vision system performs a three-dimensional scan of the gate valve blank to obtain three-dimensional point cloud data. S3. The control system generates a three-dimensional point cloud model based on the three-dimensional point cloud data, analyzes the three-dimensional point cloud model to obtain the axes of different sides of the gate valve blank, and calculates the coordinates of the current clamping center point and the current Euler angle value of the gate valve blank based on the axes. S4. The control system obtains the standard clamping center point coordinates and standard Euler angle values ​​of the pre-stored standard product, and compares them with the current clamping center point coordinates and current Euler angle values ​​of the gate valve blank to obtain the pose offset value. S5. The robot body aligns the clamping position of the gate valve blank according to the posture offset value, and then transfers the gate valve blank after the clamping position is aligned to the feeding device. S6. The hydraulic clamping device on the feeding device clamps the gate valve blank placed on the feeding device.

3. The non-contact self-aligning clamping method for gate valve blanks according to claim 2, characterized in that, In step S1, the robot gripper extends a certain distance along the guide diameter of the gate valve blank, so that the first center point of the gate valve blank coincides with the center point of the tool coordinate system of the robot gripper. The guide diameter is used as the first reference surface to perform coarse positioning on the gate valve blank, so that the gate valve blank and the standard product establish a constraint relationship in the same positioning method. In step S3, the three orthogonal axes of the gate valve blank are found in the feature points, lines and surfaces that serve as the reference in the three-dimensional point cloud model, and the intersection of the three orthogonal axes is taken as the current clamping center point.

4. The non-contact self-aligning clamping method for gate valve blanks according to claim 2, characterized in that, In step S4, the pose offset value includes the clamping center point coordinate offset value and the Euler angle offset value. The clamping center point coordinate offset value is the coordinate difference between the standard clamping center point coordinate and the current clamping center point coordinate, and the Euler angle offset value is the difference between the standard Euler angle value and the current Euler angle value.

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