Calculation method for initial pressure and contact gap Cpk of electromagnetic relay

Abstract

The invention discloses an electromagnetic relay initial pressure and contact gap Cpk calculation method, and belongs to the technical field of electromechanical components. Comprising the following steps: calibrating the visual field of an industrial camera to obtain a pixel size; programming a PLC (Programmable Logic Controller) of the industrial robot; the PLC controls the stepping motor to move the relay bottom plate to the pre-judged central position of the visual field of the industrial camera; calculating the deviation distance of the bottom plate; measuring the contact gap and the initial pressure of the relay; the relay bottom plate is reset and replaced; repeating until the batch of products are measured; and calculating the Cpk of the batch of products. According to the invention, through automatic tooling equipment, accurate and rapid measurement of the initial pressure and the contact gap of the relay base plate is realized, the Cpk of batch products is effectively calculated, the manual debugging proportion is reduced, the parameter consistency and the production efficiency of the whole machine are improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to a calculation method for an initial pressure and a contact gap Cpk of an electromagnetic relay, belonging to the technical field of electromechanical components. Background Art

[0002] 1 / 2 crystal cover sealed electromagnetic relays are widely used in the aerospace field due to their miniaturization, high reliability, long life and environmental resistance, playing a key role in circuit switching, signal transmission, etc. However, the parts composition is complex, the manufacturing process is cumbersome, the parameter testing is difficult, and it involves the mutual influence of multiple physical fields, which makes it difficult to improve the performance parameters. At the same time, problems such as low Cpk (Process Capability Index) values ​​of key processes, inconsistent product quality, low pass rate and high elimination rate are often encountered, making it particularly difficult to control the cost of the entire chain from raw materials, molds, parts, assembly to screening.

[0003] At the same time, the overall manufacturing maturity of electromechanical component products in my country is relatively low. How to reduce the proportion of manual debugging in the assembly process, reduce the number of re-adjustments after the whole machine assembly is completed, effectively improve the manufacturing maturity of electromechanical component products, and improve product quality consistency are issues that need to be urgently addressed in my country's electromechanical component manufacturing field.

[0004] At present, in the manufacturing process of electromechanical components in my country, manual, semi-automatic tooling and fully automatic tooling debugging equipment coexist in a common situation. Manual debugging accounts for a high proportion in the assembly process, and the compound adjustment process is relatively cumbersome. Automated equipment is mainly used in the production of parts and other processes. For the measurement of key shape and position parameters such as the mechanical properties of the whole machine and the contact gap, manual measurement and debugging methods are still mainly used. This method is not only inefficient, but also difficult to ensure the accuracy and consistency of the measurement results.

[0005] Initial pressure and contact gap are two important parameters in relay performance. Initial pressure is an important indicator in the reaction force characteristic curve of the relay, which directly affects key electrical parameters such as the pull-in release voltage; while the contact gap not only affects the suction curve, but is also a decisive factor in whether the arc can be stably extinguished during the operation. Therefore, accurate measurement and debugging of these two parameters are crucial to improving the overall performance of the relay. Summary of the invention

[0006] In order to solve the problems existing in the background technology, the present invention provides a method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay.

[0007] To achieve the above object, the present invention adopts the following technical solution: a method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay, the method comprising the following steps:

[0008] S1: Use the calibration plate to calibrate the field of view of the industrial camera to obtain the pixel size;

[0009] S101: focusing the industrial camera, placing the checkerboard calibration plate at the center of the field of view of the telecentric lens of the industrial camera;

[0010] S102: Adjust the placement height of the calibration board to be consistent with the height of the relay base plate;

[0011] S103: Capturing the image of the calibration plate through an industrial camera;

[0012] S104: Use Python to identify corners of the checkerboard image and calculate the distance between corners to obtain the pixel size of the industrial camera's field of view and implement field of view calibration.

[0013] S2: Program the PLC of the industrial robot;

[0014] S3: PLC controls the stepper motor to move the relay base plate to the predicted center position of the industrial camera’s field of view;

[0015] S301: Calculate the number of pulses required for the two-axis slide to move;

[0016] S302: Use PLC to input the high-speed pulse calculated in S301 to the stepper motor driver;

[0017] S303: The stepper motor driver controls the stepper motor and the lead screw to move the relay base plate to the center of the industrial camera's field of view.

[0018] S4: Calculate the deviation distance of the actual position of the base plate relative to the center of the industrial field of view;

[0019] S401: Using a computer to use a callback function to collect the relay bottom plate image in real time;

[0020] S402: performing template matching on the collected image to obtain pixel values ​​of the deviation of the bottom plate position in the image relative to the center of the field of view;

[0021] S403: using the pixel size obtained in S1, calculating the deviation distance of the actual position of the base plate relative to the predicted center of the field of view;

[0022] S404: Transmit the deviation distance to the PLC via the OPC server.

[0023] S5: Measure the relay contact gap H;

[0024] S501: performing noise reduction, template matching, and multiple reduction of the region of interest on the relay bottom plate image;

[0025] S502: Using the Canny edge detection algorithm, obtain the contour of the moving contact point and the contour of the static contact point;

[0026] S503: Fit the contact contour and measure the relay contact gap H.

[0027] S6: initial pressure value measurement;

[0028] S601: After the contact gap H is measured, a signal is transmitted to the PLC;

[0029] S602: convert the deviation distance obtained in S4 into pulse number, and drive the stepper motor to move the bottom plate to cooperate with the dynamometer;

[0030] S603: When the probe (6) of the dynamometer moves the moving spring (5) until it is separated from the static spring (4), an electrical signal is transmitted to the PLC to stop the stepper motor from rotating. At this time, the dynamometer reading is the initial pressure measurement value.

[0031] S7: When the contact gap H and the initial pressure are uploaded to the computer, a signal is sent to the PLC to drive the stepper motor to reset the relay base plate, and the industrial robot replaces the base plate;

[0032] S8: Repeat S3-S7 until the batch product is measured;

[0033] S9: Calculate the contact gap H and the Cpk of the initial pressure batch product in the computer according to the measurement data. The calculation formula of the Cpk is as follows:

[0034]

[0035] In formula (1):

[0036] T is the specification tolerance;

[0037] σ is the standard deviation;

[0038] is the data average;

[0039] U is the center value of the specification.

[0040] C a and C p They are all transfer symbols and have no meaning.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention uses automated tooling equipment to achieve accurate and rapid measurement of the initial pressure of the relay base plate and the contact gap, effectively calculates the Cpk of batch products, reduces the proportion of manual debugging, improves the consistency of parameters and production efficiency of the whole machine, and reduces production costs. In addition, the use of industrial robots to accurately transport the relay base solves the problems of low detection efficiency and poor parameter consistency caused by manual debugging, and improves the calculation efficiency of the contact system automatic detection and the key parameter Cpk of batch products. The contour recognition, fitting and calculation of the relay contacts are performed through visual recognition technology, which improves the accuracy of contact gap measurement. Real-time monitoring of key parameters during the production process ensures product quality and can promptly respond to unqualified problems in assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a structural diagram of the contact system of a 1 / 2 crystal cover sealed electromagnetic relay, where: 1 is a dynamic-closing static reed, 2 is a dynamic-closing static contact, 3 is a static-closing static contact, 4 is a static-closing static reed, and 5 is a dynamic reed;

[0044] Figure 2 is a schematic diagram of the contact gap H;

[0045] Figure 3 is a schematic diagram of initial pressure measurement;

[0046] Figure 4 is a schematic diagram of a computing system of the present invention;

[0047] Figure 5 It is a calculation flow chart of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] A method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay, the method comprising the following steps:

[0050] S1: Use the calibration plate to calibrate the field of view of the industrial camera to obtain the pixel size;

[0051] S101: Focus the industrial camera and place the checkerboard calibration plate at the center of the field of view of the telecentric lens of the industrial camera. To reduce image acquisition distortion and improve positioning and measurement accuracy, an industrial telecentric lens is selected.

[0052] S102: Adjust the placement height of the calibration board to be consistent with the height of the relay base plate;

[0053] S103: Capturing the image of the calibration plate through an industrial camera;

[0054] S104: Use Python to identify corners of the checkerboard image and calculate the distance between corners to obtain the pixel size of the industrial camera's field of view and implement field of view calibration.

[0055] S2: Program the PLC of the industrial robot; use the touch screen of the industrial robot to undertake the human-machine interface task, design the touch screen, bind the buttons and parameters with some variables in the PLC, and be mainly responsible for the industrial robot parameter configuration and equipment operation.

[0056] S3: PLC controls the stepper motor to move the relay base plate to the predicted center position of the industrial camera’s field of view;

[0057] S301: Calculate the number of pulses required for the two-axis slide to move by using the step angle, lead and subdivision number of the stepper motor driver;

[0058] S302: Use PLC to input the high-speed pulse calculated in S301 to the stepper motor driver;

[0059] S303: The stepper motor driver controls the stepper motor and the lead screw to move the relay base plate to the center of the industrial camera's field of view.

[0060] S4: Calculate the deviation distance of the actual position of the base plate relative to the center of the industrial field of view;

[0061] S401: Using a computer to use a callback function to collect the relay bottom plate image in real time;

[0062] S402: performing template matching on the collected image to obtain pixel values ​​of the deviation of the bottom plate position in the image relative to the center of the field of view;

[0063] S403: using the pixel size obtained in S1, calculating the deviation distance of the actual position of the base plate relative to the predicted center of the field of view;

[0064] S404: The deviation distance is transmitted to the PLC through the OPC server to assist in positioning the measurement of the initial pressure of the relay and improve the accuracy of the initial pressure measurement.

[0065] S5: Measure the relay contact gap H;

[0066] S501: Use Python's OpenCV toolkit to perform noise reduction, template matching, and multiple reductions of the region of interest on the relay baseplate image;

[0067] S502: Using the Canny edge detection algorithm, obtain the contour of the moving contact point and the contour of the static contact point;

[0068] S503: Fit the contact contour and measure the relay contact gap H.

[0069] S6: Measurement of initial pressure (pressure between the moving reed and the static reed in the released state);

[0070] S601: After the contact gap H is measured, a signal is transmitted to the PLC;

[0071] S602: convert the deviation distance obtained in S4 into pulse number, and drive the stepper motor to move the bottom plate to cooperate with the dynamometer;

[0072] S603: When the probe 6 of the dynamometer moves the moving reed 5 until it is separated from the static reed 4, an electrical signal is transmitted to the PLC to stop the stepper motor from rotating. At this time, the dynamometer reading is the initial pressure measurement value.

[0073] S7: When the contact gap H and the initial pressure are uploaded to the computer, a signal is sent to the PLC to drive the stepper motor to reset the relay base plate, and the industrial robot replaces the base plate;

[0074] S8: Repeat S3-S7 until the batch product is measured;

[0075] S9: Calculate the contact gap H and the Cpk of the initial pressure batch product in the computer based on the measured data. The calculation formula of Cpk is as follows:

[0076]

[0077] In formula (1):

[0078] T is the specification tolerance;

[0079] σ is the standard deviation;

[0080] is the data average;

[0081] U is the center value of the specification.

[0082] C a and C p They are all transfer symbols and have no meaning.

[0083] Since the position information feedback parameters set by this method are targeted at this model of 1 / 2 crystal cover sealed electromagnetic relay baseplate, the relative positions of the dynamometer, industrial camera, and two-axis slide should be strictly fixed during the implementation process, and when other types of relay baseplates are replaced, some positioning parameters in the PLC program should be modified.

[0084] Embodiment 1:

[0085] S1: A 2mm×2mm 20×20 chessboard calibration plate is placed at the center of the telecentric lens field of view of the industrial camera, and the calibration plate image is collected. Python is used to identify the corners of the chessboard image and calculate the corner distance to obtain the field of view pixel size and realize field of view calibration.

[0086] S2: Programming the PLC that controls the industrial robot.

[0087] S3: The selected stepper motor has a step angle of 0.9° and a lead of 4 mm. A PLC is used to input high-speed pulses to the stepper motor driver to control the two-axis slide to move the relay base plate to the center of the industrial camera's field of view.

[0088] S4: The image of the relay base plate is collected in real time by a computer, and the deviation distance of the actual position of the base plate relative to the center of the field of view is calculated. This deviation distance is transmitted to the PLC that controls the stepper motor to assist in positioning the measurement of the initial pressure of the relay.

[0089] S5: Use Python to perform Gaussian noise reduction and template matching on the relay base plate image to narrow the area of ​​interest multiple times. Use the Canny edge detection algorithm to obtain the contours of the moving contact and the static contact, fit the contact contours, and calculate the contact gap H.

[0090] S6: After the contact gap H is measured, a signal is transmitted to the PLC to drive the stepper motor to move the bottom plate to cooperate with the dynamometer to perform initial pressure measurement.

[0091] S7: Upload the measurement results to the computer, send a signal to the PLC, drive the stepper motor to reset the position of the relay base plate, and wait for the industrial robot to replace the base plate.

[0092] S8: Calculate the Cpk of the contact gap and initial pressure batch products in the computer based on the measured data. The contact gap tolerance range of this model relay is 0.28-0.31mm, and the initial pressure tolerance range is 72-88mN.

[0093] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0094] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay, characterized in that: The method comprises the following steps: S1: Use the calibration plate to calibrate the field of view of the industrial camera to obtain the pixel size; S2: Program the PLC of the industrial robot; S3: PLC controls the stepper motor to move the relay base plate to the predicted center position of the industrial camera’s field of view; S4: Calculate the deviation distance of the actual position of the base plate relative to the center of the industrial field of view; S5: Measure the relay contact gap H; S6: initial pressure value measurement; S7: When the contact gap H and the initial pressure are uploaded to the computer, a signal is sent to the PLC to drive the stepper motor to reset the relay base plate, and the industrial robot replaces the base plate; S8: Repeat S3-S7 until the batch product is measured; S9: Calculate the contact gap H and the Cpk of the initial pressure batch product in the computer based on the measurement data.

2. The method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay according to claim 1, characterized in that: The S1 comprises the following steps: S101: focusing the industrial camera, placing the checkerboard calibration plate at the center of the field of view of the telecentric lens of the industrial camera; S102: Adjust the placement height of the calibration board to be consistent with the height of the relay base plate; S103: Capturing the image of the calibration plate through an industrial camera; S104: Use Python to identify corners of the checkerboard image and calculate the distance between corners to obtain the pixel size of the industrial camera's field of view and implement field of view calibration.

3. The method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay according to claim 2, characterized in that: The S3 comprises the following steps: S301: Calculate the number of pulses required for the two-axis slide to move; S302: Use PLC to input the high-speed pulse calculated in S301 to the stepper motor driver; S303: The stepper motor driver controls the stepper motor and the lead screw to move the relay base plate to the center of the industrial camera's field of view.

4. The method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay according to claim 3, characterized in that: The S4 comprises the following steps: S401: Using a computer to use a callback function to collect the relay bottom plate image in real time; S402: performing template matching on the collected image to obtain pixel values ​​of the deviation of the bottom plate position in the image relative to the center of the field of view; S403: using the pixel size obtained in S1, calculating the deviation distance of the actual position of the base plate relative to the predicted center of the field of view; S404: Transmit the deviation distance to the PLC via the OPC server.

5. The method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay according to claim 4, characterized in that: The S5 comprises the following steps: S501: performing noise reduction, template matching, and multiple reduction of the region of interest on the relay bottom plate image; S502: Using the Canny edge detection algorithm, obtain the contour of the moving contact point and the contour of the static contact point; S503: Fit the contact contour and measure the relay contact gap H.

6. The method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay according to claim 5, characterized in that: The S6 comprises the following steps: S601: After the contact gap H is measured, a signal is transmitted to the PLC; S602: convert the deviation distance obtained in S4 into pulse number, and drive the stepper motor to move the bottom plate to cooperate with the dynamometer; S603: When the probe (6) of the dynamometer moves the moving spring (5) until it is separated from the static spring (4), an electrical signal is transmitted to the PLC to stop the stepper motor from rotating. At this time, the dynamometer reading is the initial pressure measurement value.

7. The method for calculating the initial pressure and contact gap Cpk of an electromagnetic relay according to claim 6, characterized in that: The calculation formula of Cpk described in S9 is as follows: In formula (1): T is the specification tolerance; σ is the standard deviation; is the data average; U is the center value of the specification; C a and C p They are all transfer symbols and have no meaning.

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