Machine vision controlled segmented electrode self-adjusting electrochemical machining apparatus and method

Abstract

The application discloses a machine vision controlled block electrode self-adjusting electrolytic machining device and method, relates to the field of electrolytic machining, and electrolytic machining is divided into preforming electrolytic machining and block compensation electrolytic machining; the preforming electrolytic machining stage is a stage of electrolytic machining in which a whole forming tool cathode is used as a cathode to work on a workpiece at a constant feed speed, the stage is used for primarily copying and forming the workpiece, and then the block compensation electrolytic machining stage is started; the block compensation electrolytic machining stage is used for dividing the machining area into zones, capturing image information of electrolytic machining of the workpiece and block electrodes by machine vision, analyzing and processing the block zones, obtaining actual machining gaps of the block zones, comparing and calculating the actual machining gaps with corresponding target values, and then sending instructions to a movement execution system to control specified block electrodes to perform compensation electrolytic machining, so that machining errors caused by fluctuations in conductivity along the way are eliminated, and finally, electrolytic copying and forming machining with higher machining precision is realized in the long process of the distorted workpiece.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrolytic machining in the field of special processing technology, in particular to a self-adjusting electrolytic machining device and method with block electrodes controlled by machine vision. BACKGROUND

[0002] In modern manufacturing, super-long twisted workpieces are indispensable from mold manufacturing to aerospace precision part manufacturing. For example, the structure of the aircraft engine blade is long and thin, and the surface is twisted and thin. The material used is mostly difficult-to-cut material such as high-temperature alloy. Traditional mechanical machining cannot meet the processing requirements, while electrolytic machining is widely used in the processing and manufacturing of super-long twisted workpieces due to its tool cathode without loss, good machining surface quality, and no residual stress.

[0003] However, there are still some problems to be solved in electrolytic machining of super-long twisted workpieces. Because the processing area is long, the length of the electrolyte flow path will also be lengthened to cover the entire processing area. With the increase of the length of the electrolyte flow path, the electrolyte will suffer more resistance and pressure loss during the flow process, resulting in a decrease in flow rate, especially in the far end of the flow channel. During the electrolytic machining process, gas bubbles, insoluble products and heat are generated due to electrochemical reaction, and these gas bubbles, insoluble products and heat will gradually accumulate towards the outlet with the flow of the electrolyte. On the other hand, the lengthening of the flow channel also causes a large change in the concentration of the inlet and outlet of the electrolyte during the flow process. These factors will cause a large fluctuation in the electrolyte conductivity along the path, which will seriously affect the electrolytic replication forming precision of the workpiece.

[0004] In order to solve the influence of conductivity fluctuation on machining accuracy, researchers have conducted a lot of exploration. Among them, Wang Hao et al. of Anhui University of Technology proposed a programmed power surface electrolytic machining method and device (Wang Hao Huang Guohui Rao Sichen Zhang Peng Guo Xiangqin; A programmed power surface electrolytic machining method and device[P]; Anhui Province: CN202211305079.X, 2022.10.24), two groups of assembled tool cathodes are arranged on both sides of the anode workpiece, and each group of assembled cathode blocks is programmed to be powered according to the program setting interval, which effectively adjusts the distribution of products, gas bubbles and heat, and can also preferentially remove large excess material, realize fast and uniform machining, and finally improve the electrolytic machining precision and stability of complex surface and large-size workpieces. However, different processing materials require different processing environments and process parameters, which requires a lot of process optimization and simulation in the early stage, and the fluctuation of the electrolyte conductivity along the path under the super-long flow path still needs to be solved as a key problem affecting the machining accuracy of the workpiece when machining super-long flow path twisted workpieces. SUMMARY

[0005] In view of the deficiencies in the prior art, the machine vision controlled block electrode self-adjusting electrolytic machining device and method are provided, the forming tool cathode is processed in blocks, that is, the tool cathode is divided into several block electrodes according to different machining regions, the side surfaces of adjacent block electrodes are insulated and lubricated, and finally the cathode can be used as a whole forming tool cathode to pre-form the workpiece by electrolytic machining, and each block electrode can be used as a basic machining unit to compensate the workpiece by electrolytic machining, so as to eliminate the machining error caused by the fluctuation of the electrical conductivity along the path, and finally realize the electrolytic replication forming machining with higher machining precision in the long process of the distorted workpiece.

[0006] The application achieves the above technical object through the following technical means.

[0007] The machine vision controlled block electrode self-adjusting electrolytic machining device comprises a machine vision system, a motion execution system, a fixed adjustment system, an electrolyte circulating system and a real-time monitoring system.

[0008] The machine vision system comprises a CCD high-speed camera, a computer and a motion control unit; the CCD high-speed camera captures the real-time image of the machining region, the computer calculates the actual machining gap of the workpiece and the cathode after analyzing and processing the captured image, the machining gap and the target value are compared and calculated according to the logical relationship of the set program by the computer, and then the control instruction is sent to the motion control unit, the motion control unit sends the motion instruction to the motion execution system, and the motion execution system drives the cathode to work; the electrolyte circulating system is used to provide the electrolyte; the real-time monitoring system is used to monitor the current, the electrolyte pressure and the temperature parameters in real time, and when the parameters are abnormal, the information is transmitted to the computer and the control instruction of interrupting the feeding motion and closing the pulse power switch is sent; the fixed adjustment system adjusts and fixes the workpiece and the cathode to the machining position.

[0009] In the scheme, the whole electrolytic machining process is divided into a pre-forming electrolytic machining stage and a block compensation electrolytic machining stage; the pre-forming electrolytic machining stage is the electrolytic machining stage in which the whole forming tool cathode is used as the cathode to the workpiece with constant feeding speed, the purpose of the stage is to preliminarily replicate the workpiece, and then the block compensation electrolytic machining stage is started; the block compensation electrolytic machining stage is to divide the machining region into zones, capture the image information of the workpiece and the block electrode electrolytic machining by the machine vision, analyze and process the block region, obtain the actual machining gap of each block region, compare and calculate the corresponding target value, and then send the instruction to the motion execution system to control the specified block electrode to perform the block compensation electrolytic machining;

[0010] The machine vision system comprises a CCD high-speed camera, a computer and a motion control unit; the CCD high-speed camera is arranged directly above an electrolytic machining area, captures images of the whole machining area of a workpiece and a cathode, and transmits the captured images to an image processing unit of the computer;

[0011] In the above scheme, the computer receives images transmitted by the CCD high-speed camera, the image processing unit of the computer adopts the following processing modes for the images: grayscale, median filter pretreatment, threshold segmentation to binary image, open operation of a morphological filter and Canny edge detection, and the final conversion result of the images is that boundaries of the two electrodes are set as white and other areas are set as black, the converted images are scanned line by line to obtain pixel width of the scanned lines, and the pixel width is converted into an actual machining gap according to a corresponding proportion; the computer compares and calculates the actual machining gap obtained by the image processing unit and a corresponding target value according to a logical relationship of a set program, and sends a control instruction to the motion control unit; the motion control unit receives the control instruction sent by the computer and controls a specified motor to drive a motion execution system to perform corresponding electrolytic machining motion;

[0012] The motion execution system comprises an x-axis moving unit, a motion platform, a fixed platform, a double-coordinate-axis moving unit, a grabbing robot and a pulse power supply; the motor in the x-axis moving unit receives a motion instruction sent by the motion control unit and drives the motion platform to perform x-axis constant-speed feeding motion; the motion platform is installed on the fixed platform and performs x-axis constant-speed feeding motion with the x-axis moving unit, that is, drives the whole shaped tool cathode to perform pre-shaping electrolytic machining motion, in particular, the x-axis constant-speed feeding motion of the motion platform continues during the block compensation electrolytic machining stage; the fixed platform is arranged at the lowermost part of the whole motion execution system and is installed with the x-axis moving unit; the transverse and longitudinal motors in the double-coordinate-axis moving unit receive motion instructions sent by the motion control unit and move the grabbing robot to a specified position; the grabbing robot comprises a mechanical arm and a mechanical gripper, and the two inner surfaces of the mechanical gripper are both provided with position sensors to accurately grab the grabbing slider and perform block compensation electrolytic machining motion; the positive electrode of the pulse power supply is connected with the workpiece, the negative electrode is connected with the block electrode, and the pulse power supply provides energy for electrolytic machining;

[0013] The fixed adjustment system comprises an electrolytic cell, an adjustment frame, a fixed guide rail and a grabbing slider; the electrolytic cell is a transparent glass cover plate above the workpiece and the cathode electrolytic processing area, which plays a sealing role and provides a field of view for the CCD high-speed camera to capture images; the adjustment frame adjusts the workpiece to the initial processing position and fixes the workpiece; the fixed guide rail is connected with the grabbing slider above, which plays a guiding role in the compensation movement of the segmented electrode and tightly connects the segmented electrodes together, so that all the segmented electrodes accurately form the whole shaped tool cathode in the initial processing; the grabbing slider is installed on the corresponding fixed guide rail, the grabbing slider and the segmented electrode above are fixedly connected, and position sensors are arranged on both sides of each grabbing slider to ensure that the robot accurately grabs;

[0014] The electrolyte circulation system comprises an electrolyte tank, a temperature control unit, an inlet pipeline, a one-way valve, an inlet filter, a pressure gauge, a hydraulic pump, an outlet pipeline, an outlet filter and a waste liquid tank; the electrolyte circulation system provides high-pressure electrolyte with constant temperature for the whole electrolytic processing device, ensures that the electrolytic products in the gap between the workpiece and the cathode in the processing area are smoothly discharged, and recovers the waste liquid after electrolytic processing;

[0015] The real-time monitoring system comprises a data acquisition card, a current sensor, a pressure sensor and a temperature sensor; the current sensor, the pressure sensor and the temperature sensor monitor the current, the electrolyte pressure and the temperature parameters of the whole electrolytic processing process in real time, when any parameter is abnormal, the detection signal is transmitted back to the data acquisition card, and the data is transmitted to the computer, the computer issues a control instruction to interrupt the feeding motion and close the pulse power switch, so as to avoid damage to the device caused by short circuit between the workpiece and the cathode and the like;

[0016] The machine vision controlled segmented electrode self-adjusting electrolytic processing device and method comprises the following steps:

[0017] Step S1: the adjustment frame installs the workpiece into the electrolytic cell, adjusts the workpiece to the initial processing position and fixes the workpiece; the segmented electrode is installed on the corresponding fixed guide rail, so that all the segmented electrodes accurately form the whole shaped tool cathode, the motion platform is adjusted, the whole shaped tool cathode is adjusted to the initial processing position, and the minimum gap between the whole shaped tool cathode and the workpiece is the balanced processing gap;

[0018] Step S2: the coordinate of the workpiece balanced processing gap, the error threshold of the pre-shaping electrolytic processing stage, the error threshold of the segmented compensation electrolytic processing stage and the ideal processing contour line of the workpiece is stored in the computer; the CCD high-speed camera is focused on the boundary between the workpiece and the tool cathode, the whole electrolytic processing area is subjected to light control treatment, correct exposure is ensured, noise points are reduced, and finally high-quality images are captured;

[0019] Step S3: pre-forming electrochemical machining stage: open the pulse power supply and electrolyte circulation system, start machining, the computer sends instructions to the motion control unit to control the motor of the x-axis moving unit to drive the motion platform and the overall forming tool cathode to make x-axis constant speed feeding machining movement; at the same time, in the whole machining process, the machine vision system captures, processes and scans the image information of the machining area line by line in real time, calculates the actual machining gap of all scanning lines of the workpiece and the overall forming tool cathode, then respectively subtracts the balanced machining gap, compares the difference of the scanned lines with the error threshold of the pre-forming electrochemical machining stage, and takes it as the criterion for ending the pre-forming electrochemical machining stage; if the difference of all scanning lines is less than the error threshold of the pre-forming electrochemical machining stage, the pre-forming electrochemical machining stage ends;

[0020] Step S4: Block compensation electrolytic processing stage: the constant speed feeding processing movement of the pre-forming electrolytic processing stage continues; the end time of the pre-forming electrolytic processing stage is the start time of the first round of processing of the block compensation electrolytic processing stage; the compensation electrolytic processing of the block electrode is adjusted in different rounds, in each round of compensation electrolytic processing, each block electrode has a basis for feeding forward or retreating backward in the round, that is, the target value of the round of compensation electrolytic processing, the target value of the first round of compensation electrolytic processing is the balanced processing gap, and the target value of each round of compensation electrolytic processing is the actual processing gap of each block region calculated after the first image capture in the last round of compensation electrolytic processing; in each round of compensation electrolytic processing, each block electrode is adjusted only once, and is adjusted one by one according to the absolute value size of the difference between the block electrode and the target value of the round; specifically, at the beginning of each round of compensation electrolytic processing, the image is first captured and processed, the difference between the data points corresponding to the theoretical profile line pre-stored in the computer is calculated after the actual processing profile line of the workpiece at the processing time is extracted, if the difference of all data points is within the error threshold preset in the block compensation electrolytic processing stage, the block compensation electrolytic processing stage ends, otherwise the actual processing gap of each block region is calculated, the difference between the actual processing gap and the target value of each block region is calculated, and the block electrode corresponding to the difference with the largest absolute value is selected. The calculation method of the actual processing gap of each block electrode is to select four scanning lines that divide the block region into five small regions with equal width, calculate the actual processing gap corresponding to the four scanning lines and take the average value, and the average value is the actual processing gap of the block electrode and the workpiece. The principle of adjustment of each block electrode is: if the actual processing gap of the block electrode is less than the target value of the block electrode in the round of compensation electrolytic processing, the block electrode is fed forward by the distance between the target value and the actual processing gap; if the actual processing gap of the block electrode is greater than the target value of the block electrode in the round of compensation electrolytic processing, the block electrode is retreated by the distance between the target value and the actual processing gap; when a block electrode is adjusted, it does not participate in the sorting of the difference between the actual processing gap and the target value after image capture and processing in the next block adjustment in the round.

[0021] Step S5: Turn off the pulse power supply, the electrolyte circulation system and the machine vision system, take out the workpiece, and complete the machine vision controlled block electrode self-adjusting electrolytic replication forming processing.

[0022] Beneficial effects are:

[0023] 1. The present application carries out the limit thought of the forming tool cathode in block processing, that is, the forming tool cathode is divided into several block electrodes according to different processing areas, the side of the adjacent block electrodes is insulated and lubricated, and finally the cathode can be used as a whole forming tool cathode to make the feeding electrolytic processing movement to the workpiece, and each block electrode can be used as a basic processing unit to make the feeding electrolytic processing movement to the workpiece; machine vision is introduced on the basis of the cathode block processing, the image information of the processing area is captured by a CCD high-speed camera, the data is transmitted into the image processing unit in the computer, the actual processing gap between the workpiece and the cathode is calculated after analysis and processing, then the target value is compared and calculated according to the logical relationship of the set program, and the instruction is sent to the movement execution system, and the whole forming tool cathode and the block electrode make corresponding electrolytic processing movement in different processing stages.

[0024] 2. The electrolytic processing of the present application is divided into two processing stages of pre-forming electrolytic processing and block compensation electrolytic processing; the pre-forming electrolytic processing stage is the electrolytic processing stage in which the whole forming tool cathode is used as the cathode to make the constant feeding speed to the workpiece, the purpose of this stage is to preliminarily copy the forming of the workpiece, and then the block compensation electrolytic processing stage is started; the block compensation electrolytic processing stage is to divide the processing area, capture the image information of the electrolytic processing of the workpiece and the block electrode by machine vision, analyze and process the block area, and obtain the actual processing gap of each block area, compare and calculate the corresponding target value, send the instruction to the movement execution system, and control the specified block electrode to make compensation electrolytic processing, so as to eliminate the processing error caused by the fluctuation of the electrical conductivity along the way, and finally realize the electrolytic copy forming processing with higher processing precision in the super-long process of the twisted workpiece.

[0025] 3. The method of the present application adopts the machine vision controlled block tool electrode self-adjusting electrolytic processing, which is suitable for the super-long process of large twisted workpieces, the profile of the workpiece is preliminarily copied by pre-forming electrolytic processing, and then the copy processing error caused by the fluctuation of the electrical conductivity along the way in the super-long process is corrected by block compensation electrolytic processing, so as to greatly improve the copy forming precision of the electrolytic processing of large twisted workpieces.

[0026] 4. For the problem that the comprehensive influence law of complex multi-physical fields such as processing gap, electric field and flow field on electrolytic processing is difficult to grasp, the machine vision as a completely active, non-contact and easy-to-achieve information integration measurement and judgment method can achieve or even exceed the copy precision obtained by a large number of simulation and process parameter optimization in the early stage.

[0027] 5. The limit idea of the block electrode of the present application divides the whole shaped tool cathode into several small block electrodes, which greatly reduces the difficulty and cost of tool cathode design, processing and correction.

[0028] 6. The limit idea of the block electrode of the present application divides the whole shaped tool cathode into several small block electrodes, which greatly reduces the difficulty and cost of tool cathode design, processing and correction. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The overall structure schematic diagram of the block electrode self-adjusting electrolytic machining device controlled by machine vision;

[0030] Figure 2 The schematic diagram of the pre-shaping electrolytic machining stage;

[0031] Figure 3 The schematic diagram of the block compensation electrolytic machining stage;

[0032] Figure 4 The schematic diagram of the logic flow of the computer instruction of the pre-shaping electrolytic machining stage;

[0033] Figure 5 The schematic diagram of the logic flow of the computer instruction of the block compensation electrolytic machining stage;

[0034] Figure 6 The schematic diagram of the CCD collection of a block electrode in the block compensation electrolytic machining stage.

[0035] The symbols are as follows:

[0036] 1-CCD high-speed camera; 2-adjusting frame; 3-workpiece; 4-electrolytic tank; 5-fixed platform; 6-moving platform; 7-fixed guide rail; 8-grabbing sliding block; 9-block electrode; 10-tool cathode; 11-liquid outlet pipeline; 12-liquid outlet filter; 13-waste liquid tank; 14-electrolyte tank; 15-liquid inlet pipeline; 16-hydraulic pump; 17-temperature control unit; 18-liquid inlet filter; 19-pressure gauge; 20-one-way valve; 21-temperature sensor; 22-pressure sensor; 23-data acquisition card; 24-computer; 25-motion control unit; 26-current sensor; 27-pulse power supply; 28-longitudinal motor; 29-longitudinal guide rail; 30-longitudinal screw; 31-longitudinal bearing seat; 32-lateral bearing seat; 33-lateral screw; 34-mechanical clamping jaw; 35-mechanical arm; 36-lateral sliding block; 37-lateral motor; 38-lateral guide rail; 39-screw; 40-guide rail; 41-motor. DETAILED DESCRIPTION

[0037] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals and characters throughout the figures denote the same elements or elements with the same functions. The embodiments described below are exemplary and are intended to explain the present application, and are not intended to limit the present application.

[0038] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0039] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] The present application carries out the limit idea of block processing on the forming tool cathode, that is, the forming tool cathode is divided into several block electrodes 9 according to different processing areas, the side surfaces of adjacent block electrodes 9 are insulated and lubricated, and finally the cathode can be used as a whole forming tool cathode to make a feeding electrolytic processing movement to the workpiece, and each block electrode 9 can be used as a basic processing unit to make a feeding electrolytic processing movement to the workpiece respectively; machine vision is introduced on the basis of the block processing of the cathode, image information of the processing area is captured by a CCD high-speed camera 1, data is transmitted into an image processing unit in the computer 24, the actual processing gap between the workpiece and the cathode is calculated after analysis and processing, then the actual processing gap is compared with the corresponding target value according to the logical relationship of the set program, and finally an instruction is sent to the movement execution system, the whole forming tool cathode and the block electrodes are controlled to make preforming electrolytic processing and block compensation electrolytic processing movements in different processing stages respectively; wherein, the principle of detecting the processing gap between the workpiece and the cathode is to find the gray level jump position of the gray level matrix of the image, and the processing mode is to take gray level, median filter pretreatment, threshold segmentation to convert into a binary image, open operation of a morphological filter and Canny edge detection respectively, the final conversion result of the image is to form a smooth boundary of the anode and the cathode, the boundaries of the two electrodes are set to white, and other areas are set to black, the pixel width of different scanning lines is obtained after scanning the converted image line by line, and the actual processing gap of different scanning lines is calculated through the corresponding proportion;

[0041] A machine vision controlled block electrode self-adjusting electrolytic machining device, comprising a machine vision system, a movement execution system, a fixed adjustment system, an electrolyte circulation system and a real-time monitoring system;

[0042] The machine vision system captures, analyzes and processes the images of the workpiece and the cathode in the processing area, obtains the actual processing gap between the workpiece and the cathode at different processing times, then compares and calculates the actual processing gap with the corresponding target value according to the logical relationship of the set program, and finally sends an instruction to the movement execution system, the whole forming tool cathode 10 and the block electrode 9 are controlled to make corresponding electrolytic processing movements in the preforming electrolytic processing stage and the block compensation electrolytic processing stage respectively;

[0043] Specifically, the machine vision system comprises a CCD high-speed camera 1, a computer 24 and a motion control unit 25; the CCD high-speed camera 1 is arranged above the electrolytic machining area, captures images of the whole machining area of the workpiece and the cathode, and transmits the captured images to an image processing unit of the computer 24; the computer 24 analyzes and processes the images transmitted by the CCD high-speed camera 1 to calculate the actual machining gap; the computer 24 compares the actual machining gap obtained by the image processing unit with the corresponding target value according to the logical relationship of the set program, and then sends a control instruction to the motion control unit 25; the computer 24 is connected with a data acquisition card 23, receives abnormal information of current, electrolyte pressure and temperature parameters transmitted by the data acquisition card 23, and sends an instruction to interrupt the feeding motion and the pulse power supply 27 switch; the motion control unit 25 receives the instruction sent by the computer 24, and controls the specified motor to drive the cathode to perform corresponding electrolytic machining motion.

[0044] Specifically, during the pre-forming electrolytic machining stage, the computer 24 sends an instruction to the motion control unit 25 to control the motor 41 of the x-axis moving unit, so as to drive the motion platform 6 and the tool cathode 10 to perform the feeding machining motion at a constant speed along the x-axis; during the whole pre-forming electrolytic machining stage, the machine vision captures, analyzes and processes images in real time, and then scans the actual machining gap of the workpiece 3 and the tool cathode 10 row by row, and the difference between the actual machining gap and the balanced machining gap is obtained, and the difference value is compared with the preset error threshold value; if the difference value is less than the error threshold value, the computer 24 sends an instruction to stop the pre-forming electrolytic machining; the machining state of the pre-forming electrolytic machining stage is shown in the following table Figure 2 Figure 2 The left side is the initial machining moment, and the right side is a moment in the machining process;

[0045] Specifically, during the block compensation electrolytic machining stage, the feeding machining motion at a constant speed along the x-axis of the motion platform 6 in the pre-forming electrolytic machining stage continues, and at the same time, the actual machining gap of each block machining area is calculated by row-by-row scanning, and then an instruction is sent to the motion control unit 25 to control the corresponding block electrode 9 to perform the compensation electrolytic machining motion, so as to compensate the machining error of different machining areas caused by different electrical conductivities by performing the compensation electrolytic machining;

[0046] ​The end time of the pre-forming electrochemical machining stage is the start time of the first round of machining of the block compensation electrochemical machining stage; the compensation electrochemical machining of the block electrode 9 is adjusted in different rounds, and in each round of compensation electrochemical machining, each block electrode 9 has a basis for advancing or retreating in the round, i.e., the target value of the round of compensation electrochemical machining, the target value of the first round of compensation electrochemical machining is the balanced machining gap, and the target value of each round of compensation electrochemical machining is the actual machining gap of each block area calculated after the first image capture in the last round of compensation electrochemical machining; in each round of compensation electrochemical machining, each block electrode 9 is adjusted only once, and is adjusted one by one according to the absolute value of the difference between the block electrode 9 and the target value of the round;

[0047] Specifically, at the beginning of each round of compensation electrochemical machining, the image is first captured and processed, and the difference value of the data point corresponding to the theoretical profile line calculated and pre-stored in the computer 24 is extracted. If the difference value of all data points is within the preset error threshold, the block compensation electrochemical machining stage ends, otherwise the actual machining gap of each block area at this time is calculated, and the difference between the actual machining gap and the target value of each block area is calculated, and the block electrode 9 corresponding to the largest absolute value is selected for adjustment. The calculation method of the actual machining gap of the block electrode 9 is to select four scanning lines that divide the block area into five small areas of equal width, calculate the actual machining gap corresponding to the four scanning lines and take the average value, and the average value is the actual machining gap of the block electrode 9 and the workpiece 3.

[0048] Specifically, the principle of adjustment of each block electrode 9 is: if the actual machining gap of the block electrode 9 is less than the target value of the block electrode 9 in the current round of compensation electrochemical machining, the block electrode 9 is advanced by the difference between the target value and the actual machining gap; if the actual machining gap of the block electrode 9 is greater than the target value of the block electrode 9 in the current round of compensation electrochemical machining, the block electrode 9 is retreated by the difference between the target value and the actual machining gap; when a block electrode 9 is adjusted, it does not participate in the sorting of the difference between the actual machining gap and the target value after image capture and processing in the next block adjustment in the current round. Block electrode machining state reference of block compensation electrochemical machining stage Figure 3 As shown in the figure, Figure 3 The left side is the initial machining time, and the right side is the machining end time;

[0049] Figure 6 In the process of the experiment of block electrode compensation electrochemical machining, the images of a block electrode at different machining times captured by a CCD high-speed camera prove that the copying accuracy of the plane after block electrode compensation electrochemical machining is significantly improved;

[0050] The motion execution system comprises an x-axis moving unit, a motion platform 6, a fixed platform 5, a double-coordinate-axis moving unit, a grabbing robot and a pulse power supply 27; specifically, the x-axis moving unit comprises a motor 41, a guide rail 40, a screw 39, a bearing seat and a sliding block, the motor 41 of the x-axis moving unit receives a control signal of the motion control unit 25, drives the motion platform 6 and the tool cathode 10 to make a constant-speed feeding processing motion in the x-axis direction, that is, a preforming electrolytic processing motion; the double-coordinate-axis moving unit and the fixed guide rail 7 are fixed on the motion platform 6; the fixed platform 5 is located at the lowermost part of the whole device;

[0051] Specifically, the double-coordinate moving unit comprises a longitudinal motor 28, a longitudinal guide rail 29, a longitudinal screw 30, a longitudinal bearing seat 31, a longitudinal sliding block, a transverse guide rail 38, a transverse motor 37, a transverse sliding block 36, a transverse screw 33 and a transverse bearing seat 32; the longitudinal motor 28 of the double-coordinate moving unit receives a motion instruction sent by the motion control unit 25, moves the transverse guide rail 38 to a designated block area, and the transverse motor 37 of the double-coordinate moving unit receives a motion instruction sent by the motion control unit 25, moves the grabbing robot to a grabbing position of the corresponding grabbing sliding block 8;

[0052] Specifically, the grabbing robot comprises a mechanical jaw 34 and a mechanical arm 35, the mechanical arm 35 is fixedly connected with the mechanical jaw 34 and the transverse sliding block 36 on the two sides, respectively, the two inner sides of the mechanical jaw 34 are provided with position sensors, when the mechanical jaw 34 moves to the position sensor arranged on the grabbing sliding block 8, the mechanical jaw 34 immediately accurately grabs the grabbing sliding block 8, and performs a block compensation electrolytic processing motion; the positive electrode of the pulse power supply 27 is connected with the workpiece 3, the negative electrode is connected with the block electrode 9, and energy is provided for electrolytic processing;

[0053] The fixed adjustment system comprises an adjustment frame 2, an electrolytic tank 4, a fixed guide rail 7 and a grabbing sliding block 8; the adjustment frame 2 adjusts and fixes the workpiece 3 to an initial processing position; the uppermost part of the electrolytic tank 4 is a transparent glass cover plate, which plays a sealing role and provides a field of view for the CCD high-speed camera 1 to capture images, a special flow channel is arranged between the workpiece 3 and the cathode in the electrolytic tank 4, so that the electrolyte can flow smoothly; the fixed guide rail 7 is installed in order on the motion platform 6 with the same gap, the grabbing sliding block 8 is installed above, the fixed guide rail 7 plays a guiding role for the feeding compensation motion of the block electrode 9, and tightly connects the block electrodes together, so that all the block electrodes 9 accurately form the whole tool cathode 10 at the initial processing time; the grabbing sliding block 8 is installed on the corresponding fixed guide rail 7, the grabbing sliding block 8 and the block electrode 9 above are fixedly connected, and the two sides of each grabbing sliding block 8 are provided with position sensors, so as to ensure that the grabbing robot is accurately grabbed;

[0054] The electrolyte circulation system comprises a temperature control unit 17, an electrolyte tank 14, an inlet pipeline 15, a hydraulic pump 16, an inlet filter 18, a pressure gauge 19, a one-way valve 20, an outlet pipeline 11, an outlet filter 12 and a waste liquid tank 13; the electrolyte circulation system provides high-pressure electrolyte with constant temperature for the whole electrolytic processing device, ensures that the electrolytic products between the workpiece and the cathode gap in the processing area are smoothly discharged, and recycles the waste liquid after electrolytic processing;

[0055] The real-time monitoring system comprises a data acquisition card 23, a temperature sensor 21, a pressure sensor 22 and a current sensor 26; the temperature sensor 21, the pressure sensor 22 and the current sensor 26 monitor the temperature, the electrolyte pressure and the current parameters of the whole electrolytic processing process in real time; when any parameter is abnormal, a detection signal is transmitted back to the data acquisition card 23, and data is transmitted to a computer 24; the computer 24 issues a control instruction of interrupting the feeding movement and closing a pulse power supply 27 switch, so as to avoid damage to the device caused by short circuit between the workpiece and the cathode and the like.

[0056] A method for machine vision controlled block electrode self-adjusting electrolytic processing, comprising the following steps:

[0057] S1: the block electrode 9 is fixedly connected with the grabbing sliding block 8, and the grabbing sliding block 8 is installed on the corresponding fixed guide rail 7; the relative position of the block electrode 9 is adjusted on the fixed guide rail 7 to accurately constitute the whole shaped tool cathode 10; the whole shaped tool cathode 10 and the workpiece 3 are adjusted to the initial processing position by adjusting the motion platform 6 and the adjusting frame 2, and the minimum processing gap between the two is ensured to be the balanced processing gap of the processing material;

[0058] S2: the balanced processing gap of the workpiece, the error threshold of the pre-shaping electrolytic processing stage, the error threshold of the block compensation processing stage and the coordinates of the ideal processing contour line of the workpiece are stored in the computer 24; the CCD high-speed camera 1 is focused on the boundary of the workpiece 3 and the whole shaped tool cathode 10, the light control processing of the whole electrolytic processing area is performed, correct exposure is ensured, noise points are reduced, and finally high-quality images are captured;

[0059] S3: Pre-forming electrochemical machining stage: open the pulse power supply 27 and the electrolyte circulation system, the computer 24 sends instructions to the motion control unit 25 to control the motor 41 of the x-axis moving unit to drive the motion platform 6 and the overall forming tool cathode 10 to make the x-axis constant speed feeding machining movement; during the machining process in this stage, the CCD high-speed camera 1 captures the images of the machining area in real time and transmits them to the image processing unit of the computer 24, the image processing unit analyzes and processes the images and obtains the actual machining gap of each scanning line between the workpiece 3 and the overall forming tool cathode 10 through line-by-line scanning, and then subtracts the balanced machining gap to compare the difference with the error threshold of the pre-forming electrochemical machining stage, which is used as the criterion for ending the pre-forming electrochemical machining stage; if the difference between the actual machining gap and the balanced machining gap of all scanning lines is less than the error threshold of the pre-forming electrochemical machining stage, the pre-forming electrochemical machining stage ends; the machining state of the pre-forming electrochemical machining stage is shown in Fig. 4. Figure 2

[0060] S4: Block compensation electrochemical machining stage: the x-axis constant speed feeding machining movement in the pre-forming electrochemical machining stage continues; at the beginning of each round of compensation electrochemical machining, the images are first captured and processed, and then the difference between the data points corresponding to the theoretical profile line pre-stored in the computer 24 and the actual machining profile line at that moment is calculated; if the difference of all data points is within the preset error threshold, the block compensation electrochemical machining stage ends, otherwise, the actual machining gap of each block area at that moment is calculated, and the difference between the actual machining gap and the target value of each block area is calculated, and the block electrode 9 corresponding to the largest absolute value of the difference is selected; the principle of adjustment of each block electrode 9 is as follows: if the actual machining gap of the block electrode 9 is less than the target value of the block electrode 9 in this round of compensation electrochemical machining, the block electrode 9 is fed forward by the distance between the target value and the actual machining gap; if the actual machining gap of the block electrode 9 is greater than the target value of the block electrode 9 in this round of compensation electrochemical machining, the block electrode 9 is fed backward by the distance between the target value and the actual machining gap; when a block electrode 9 is adjusted, it will not participate in the sorting of the difference between the actual machining gap and the target value in the next block adjustment in this round. The machining state of the block electrode in the block compensation electrochemical machining stage is shown in Fig. 5. Figure 3

[0061] S5: Turn off the pulse power supply 27, the temperature control unit 17, the hydraulic pump 16 and the machine vision system, take out the workpiece 3, and complete the machining of the machine vision controlled block tool electrode self-adjusting electrochemical replication forming.

[0062] ​​In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0063] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary, and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application without departing from the principles and spirit of the present application.

Claims

1. A machine vision controlled, block electrode self-adjusting electrochemical machining apparatus, characterized in that, The utility model relates to a kind of electrolytic machining system, including machine vision system, motion execution system, fixed adjustment system, electrolyte circulation system and real-time monitoring system;Wherein, the machine vision system includes CCD high-speed camera (1), computer (24) and motion control unit (25);CCD high-speed camera (1) captures the real-time image of processing area, and computer (24) calculates the actual processing gap of workpiece (3) and tool cathode (10) after analyzing and processing the image captured, and the processing gap and target value are compared and calculated by computer (24) according to the logic relationship of setting program, then control instruction is sent to motion control unit (25), and motion control unit (25) sends motion instruction to motion execution system, and the motion execution system drives tool cathode (10) to work;The electrolyte circulation system is used to provide electrolyte;The real-time monitoring system is used to monitor current, electrolyte pressure and temperature parameters in real time, and when any parameter is abnormal, information is transmitted to computer (24) and control instruction of interrupting feeding motion and closing pulse power supply (27) switch is sent;The fixed adjustment system adjusts workpiece (3) and tool cathode (10) to processing position and fixes;Tool cathode (10) includes several block electrodes (9), and the motion execution system provides preformed electrolytic machining motion for tool cathode (10) and provides block compensation electrolytic machining motion for block electrode (9);The side of adjacent block electrode (9) that contacts is insulated and lubricated, so that block electrode (9) can form tool cathode (10) and do preformed electrolytic machining motion, and individual block electrode (9) can also do block compensation electrolytic machining motion to workpiece (3) as basic processing unit;The compensation electrolytic machining motion of each block electrode (9) is calculated by machine vision system in real time, and after comparison and calculation according to the logic relationship of setting program, instruction control is sent to specified block electrode (9) to carry out block compensation electrolytic machining;The motion execution system includes x-axis moving unit, motion platform (6), fixed platform (5), double-coordinate-axis moving unit, grabbing robot and pulse power supply (27);X-axis moving unit receives the motion instruction of motion control unit (25), provides the feeding motion of motion platform (6) x-axis, so as to provide preformed electrolytic machining motion for tool cathode (10);Double-coordinate-axis moving unit receives the motion instruction of motion control unit (25), moves grabbing robot to specified grabbing position, then adjusts block electrode (9), so as to provide block compensation electrolytic machining motion for block electrode (9);The positive pole of pulse power supply (27) is connected with workpiece (3), and the negative pole is connected with block electrode (9), to provide energy for electrolytic machining;The fixed adjustment system includes electrolytic cell (4), adjusting frame (2), fixed guide rail (7) and several grabbing sliders (8);The upper portion of electrolytic cell (4) is provided with transparent glass cover plate;Adjusting frame (2) adjusts and fixes workpiece (3);The fixed guide rail (7) provides the guiding effect for the compensation movement of the segmented electrode (9), and arranges the segmented electrodes (9) to form the whole shaped tool cathode (10); the grabbing sliding block (8) is fixedly connected with the segmented electrode (9), and the position sensor is arranged on both sides of the grabbing sliding block (8), so that the grabbing sliding block (8) can be grabbed by the grabbing robot.

2. The machine vision controlled, segmented electrode self-adjusting electrochemical machining apparatus of claim 1, wherein, The electrolyte circulation system comprises an electrolyte tank (14), a temperature control unit (17), an inlet pipeline (15), a hydraulic pump (16), an inlet filter (18), a pressure gauge (19), a one-way valve (20), an outlet pipeline (11), an outlet filter (12) and a waste liquid tank (13); the temperature control unit (17) is arranged on the electrolyte tank (14) and used for adjusting the temperature of the electrolyte tank (14); one end of the inlet pipeline (15) is arranged in the electrolyte tank (14), and the other end is arranged at a machining position of the workpiece (3); the inlet pipeline (15) is sequentially provided with the hydraulic pump (16), the inlet filter (18), the pressure gauge (19) and the one-way valve (20); electrolyte after electrolysis is flowed into the waste liquid tank (13) through the outlet pipeline (11) and the outlet filter (12).

3. The machine vision controlled, segmented electrode self-adjusting electrochemical machining apparatus of claim 2, wherein, A pressure sensor (22) and a temperature sensor (21) are arranged near an outlet of the inlet pipeline (15); the pressure sensor (22) and the temperature sensor (21) are used for monitoring the temperature and the pressure of electrolyte at the outlet respectively; and the pressure sensor (22) and the temperature sensor (21) are electrically connected with a data acquisition card (23).

4. The machine vision controlled, segmented electrode self-adjusting electrochemical machining apparatus of claim 1, wherein, The computer (24) analyzes and processes the captured image, including detecting the actual machining gap of the workpiece (3) and the cathode; the principle is to find the gray level jump position of the gray level matrix of the image; the processing mode is that the image is subjected to gray levelization, median filter pretreatment, threshold segmentation to be converted into a binary image, an opening operation of a morphological filter and Canny edge detection; the final conversion result of the image is to form smooth boundaries of the anode and the cathode; the boundaries of the two electrodes are set to be white, and other regions are set to be black; the pixel width of different scanning lines is obtained after the converted image is scanned line by line; the actual machining gap of different scanning lines is calculated through the corresponding proportion; the preformed electrolytic machining movement and the block compensation electrolytic machining movement are controlled by the machine vision system.

5. A method of machining with a machine vision controlled segmented electrode self-adjusting electrochemical machining apparatus according to any one of claims 1 to 4, characterized in that, The method comprises a preformed electrolytic machining stage and a block compensation electrolytic machining stage. In the preformed electrolytic machining stage, the computer (24) sends an instruction to a motion control unit (25) to control the motion platform (6) and the tool cathode (10) to make an x-axis feeding machining movement at a constant speed; meanwhile, the machine vision system captures, processes and scans the image information of the machining area line by line in real time, calculates the actual machining gap of all scanning lines of the workpiece (3) and the tool cathode (10), and then respectively subtracts the balanced machining gap to compare the difference of the scanned lines with an error threshold of the preformed electrolytic machining stage, so as to serve as a criterion for ending the preformed electrolytic machining stage; if the difference of all scanning lines is less than the error threshold, the preformed electrolytic machining stage is ended. The block compensation electrolytic processing stage: the x-axis feed processing movement of the preforming electrolytic processing stage continues at a constant speed; the block compensation electrolytic processing stage is divided into different rounds of block adjustment, and in each round of block compensation electrolytic processing, each block electrode (9) has a basis for forward feeding or backward retreating in the round, i.e., the target value of the block compensation electrolytic processing in the round, and the target value of the first round of compensation electrolytic processing is the balanced processing gap, and the target value of each round of compensation electrolytic processing after that is the actual processing gap of each block region calculated after the first image capture in the last round of compensation electrolytic processing; In each round of compensation electrolytic processing, each block electrode (9) is adjusted only once, and the adjustment is performed in order of the absolute value of the difference between the block electrode (9) and the target value of the round; specifically, at the beginning of each round of compensation electrolytic processing, the image is first captured and processed, and the actual processing contour line of the workpiece at the processing time is extracted, and the difference between the corresponding data points of the theoretical contour line calculated and pre-stored in the computer (24) is calculated, if the difference of all data points is within the preset error threshold, the block compensation electrolytic processing stage ends, otherwise, the actual processing gap of each block region is calculated, and the difference between the actual processing gap and the target value of each block region is calculated, and the block electrode (9) corresponding to the largest absolute value of the difference is selected for adjustment; the calculation method of the actual processing gap of the block electrode (9) is to select four scanning lines that divide the block region into five small regions of equal width, calculate the actual processing gap corresponding to the four scanning lines and take the average, and the average value calculated is the actual processing gap of the block electrode (9) and the workpiece (3).

6. The method of claim 5, wherein, The principle of block adjustment is: if the actual processing gap of the block electrode (9) is less than the target value of the block electrode (9) in the current round of compensation electrolytic processing, the block electrode (9) is fed forward by the difference between the target value and the actual processing gap; if the actual processing gap of the block electrode (9) is greater than the target value of the block electrode (9) in the current round of compensation electrolytic processing, the block electrode (9) is retreated by the difference between the target value and the actual processing gap; when a block electrode (9) is adjusted, it does not participate in the sorting of the difference between the actual processing gap and the target value after image capture and processing in the next block adjustment in the round.

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