On-line monitoring method for positioning precision of welding tool positioning pin

Abstract

The invention relates to an online monitoring method for the positioning precision of a welding tool positioning pin. Two lasers and one sensor are used as a set of monitors, two laser beams in the same set of monitors are irradiated to the sensor in parallel, and the two sets of monitors are vertically installed in the same horizontal plane with the outer surface of the positioning pin as the reference. During initial installation, the master control box controls the laser to irradiate the outer surface of the positioning pin and collect data on the sensor, the light beam edge shielded by the positioning pin is calculated, the average of the two laser beam edges of the same monitor is taken as the initial position in the direction, the difference between the two edges is taken as the diameter, and the average of the diameters measured by the two monitors is taken as the initial diameter. During working, the current positions and the diameters of the positioning pin in the two horizontal directions are calculated according to a mounting method, the initial value during mounting is subtracted to obtain the horizontal position degree and the diameter variation, and online monitoring of the positioning precision of the positioning pin is achieved. The invention belongs to the field of laser measurement and can be applied to online monitoring of welding tools.

Description

Technical Field

[0001] The invention relates to an online monitoring method for positioning accuracy of a positioning pin of a welding tool, which is suitable for measuring the positioning accuracy of a welding tool. Background Art

[0002] As the installation skeleton of the car, the accuracy of the body in white determines the installation and matching quality of the car. As the positioning tooling of the body in white, the installation accuracy of the body in white welding line tooling determines the assembly accuracy of the body in white. In the positioning of the welding tooling, the positioning pins and the positioning blocks work together to maintain the transferability of the positioning reference and the dimensional stability of the welded parts. Due to the frequent loading and unloading of welded parts during the manufacturing process, the positioning pins may be worn or offset in the lateral direction, which in turn affects the manufacturing accuracy of the welded parts. Therefore, the positioning accuracy of the positioning pins needs to be monitored and calibrated regularly. At present, the monitoring of the positioning accuracy of the positioning pins of welding tooling mainly uses a three-coordinate measuring instrument for manual measurement during non-working hours. Each measurement requires the removal of the positioning pins. The measurement process is cumbersome, time-consuming, and costly. In addition, it is impossible to obtain the information of the positioning pin diameter and horizontal position in real time, making it difficult to continuously ensure the welding accuracy. With the growth of the demand for precision welding, higher requirements are put forward for the high precision and reliability of welding. Traditional manual monitoring methods can no longer meet the current production and manufacturing needs. Therefore, it is necessary to monitor the positioning accuracy of the welding tooling positioning pins in real time and with high precision online.

[0003] In high-precision welding, the horizontal position error of the welding tooling locating pin is often controlled within 0.1mm, and the diameter error of the locating pin needs to be controlled within 0.5mm, so higher requirements are placed on monitoring accuracy. The diameter and horizontal position of the locating pin are the basis for ensuring its positioning accuracy. If a contact measurement monitoring solution is adopted, the positioning accuracy will inevitably be destroyed. As time accumulates, the positioning accuracy of the locating pin cannot be guaranteed, so a non-contact real-time monitoring solution is required. For the measurement of the diameter of the locating pin, the non-contact outer diameter measuring instrument is a more common non-contact displacement monitoring method. However, the non-contact outer diameter measuring instrument requires a closer distance to the locating pin, which will affect the loading and unloading of the welded parts and cannot be fixedly installed, so online monitoring cannot be achieved. For the horizontal position of the locating pin, a laser rangefinder can generally be used, but the laser rangefinder is relatively expensive and is not suitable for the monitoring of the horizontal position of the locating pin. In order to realize the online monitoring of the locating pin of the welding tooling, a measurement solution that does not affect the loading and unloading of the welded parts, can be fixedly installed with a measuring instrument and has a low cost is urgently needed. The solution must meet the following conditions:

[0004] (1) Non-contact measurement does not affect positioning accuracy.

[0005] (2) It can be fixedly installed on the welding tooling without affecting its normal operation.

[0006] (3) The measurement accuracy and monitoring frequency meet the monitoring requirements.

[0007] (4) The system cost is consistent with the positioning of welding tooling. Summary of the invention

[0008] The present invention solves the following technical problems of the traditional welding tool positioning pin accuracy measurement:

[0009] (1) The measurement accuracy is low and it is difficult to meet the needs of high-precision measurement.

[0010] (2) The monitoring frequency is low and the positioning accuracy cannot be guaranteed continuously.

[0011] (3) It is impossible to obtain the accuracy data of the positioning pins in real time, and it is impossible to automatically identify and warn of potential quality problems.

[0012] The technical solution of the present invention:

[0013] Since the outer surface of the locating pin directly contacts the welded part, the monitoring of the positioning accuracy of the locating pin is achieved by monitoring the horizontal position and diameter of the locating pin. Therefore, a monitoring method that can not only avoid direct interference with the welding process, but also quickly process the monitoring data and detect positioning errors in a timely manner is required. The monitoring platform needs to have a flexible architecture and be easy to install. The monitoring parameters and monitoring frequency can be adjusted according to actual needs. The platform should also adopt a modular design for easy installation and maintenance. The monitoring module can be flexibly selected and configured according to the specific welding process and space restrictions. The monitoring system should have real-time data processing capabilities, analyze the horizontal position and diameter of the locating pin through algorithms, and identify and feedback errors in a timely manner. It should also have data storage functions to record historical measurement data for subsequent analysis and quality traceability. It can also cope with the effects of temperature changes, smoke, vibration, etc. during the welding process to adapt to a variety of welding scenarios and material characteristics. A non-contact monitoring platform is constructed with lasers and charge coupled devices (CCDs). The data is collected and processed in real time through the main control box, and finally the online monitoring of the positioning accuracy of the locating pin is realized.

[0014] The steps for online monitoring of positioning pin positioning accuracy are as follows:

[0015] (1) Initial installation: Adjust the laser beam to the same height as the outer surface of the positioning pin. The laser beam irradiates the outer surface of the positioning pin. Install the sensor horizontally so that its photosensitive surface is perpendicular to the laser beam. Adjust the horizontal position of the laser and the sensor to ensure that they do not affect the loading and unloading of the weldment.

[0016] (2) Perform initial measurement: The main control box controls two sets of monitors to monitor the outer surface of the positioning pin in two directions, collect laser data, smooth the data, and use the processed data edge as the laser irradiation edge. Record the position x0 of the lower edge of the laser irradiation area on sensor 1; the position x1 of the upper edge; record the position y0 of the right edge of the laser irradiation area of ​​sensor 2; the position y1 of the left edge;

[0017] (3) Calculate the initial position of the positioning pin in the x direction:

[0018] H x =(x0+x1) / 2 (1)

[0019] Diameter in x direction:

[0020] D x =x0-x1 (2)

[0021] Initial position in the y direction:

[0022] H y =(y0+y1) / 2 (3)

[0023] Diameter in the y direction:

[0024] D y =y0-y1 (4)

[0025] Initial diameter of dowel pin:

[0026] D0=(D x +D y ) / 2 (5)

[0027] (4) After initialization is completed, enter real-time monitoring with a frequency of 1 time / minute.

[0028] (5) During monitoring, the main control box controls the laser to illuminate the outer surface of the positioning pin in parallel, collects laser data on the sensor, and calculates the position x2 and the upper edge position x3 of the laser beam of sensor 1; the right edge position y2 and the left edge position y3 of the laser beam of sensor 2;

[0029] (6) Calculate the current position of the positioning pin in the x direction:

[0030] H' x =(x2+x3) / 2 (6)

[0031] Diameter in the x-direction:

[0032] D x =x2-x3 (7)

[0033] Current position in the y direction:

[0034] H' y =(y2+y3) / 2 (8)

[0035] Diameter in the y direction:

[0036] D' y =y2-y3 (9)

[0037] Current diameter of dowel pin:

[0038] D1=(D' x +D' y ) / 2 (10)

[0039] Horizontal position in the x direction:

[0040] ΔH x =H' x -H x (11)

[0041] Horizontal position in the y direction:

[0042] ΔH y =H' y -H y (12)

[0043] Change in locating pin diameter:

[0044] ΔD=D1-D0 (13)

[0045] (7) Output the horizontal position and diameter change of the positioning pin, and determine whether it exceeds the error range. If it exceeds the error range, an alarm is triggered to achieve online monitoring of the positioning accuracy of the positioning pin.

[0046] (8) After completing the measurement, turn off the laser through the main control box and wait for the next monitoring.

[0047] Compared with the existing solutions, the solution of the present invention has the following main advantages:

[0048] Compared with the traditional positioning pin positioning accuracy monitoring method, the present invention constructs an efficient online monitoring platform based on the positioning pin. The platform can accurately monitor the outer surface of the positioning pin in two directions. During the monitoring process, the sensor collects the received laser data in real time and uses the data processing algorithm to quickly calculate the horizontal position and diameter of the positioning pin. This enables the system to provide accurate measurement results in a short time, thereby ensuring that the accuracy of the positioning pin is always kept within a controllable range.

[0049] In addition, this method significantly reduces interference with normal production processes. With high-frequency and efficient monitoring capabilities, the system can continuously track the status of the positioning pins during the production process, and promptly detect and correct potential positioning errors, thereby effectively avoiding welding quality problems caused by inaccurate positioning. Through this solution, production efficiency is improved and welding quality is effectively guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Principle diagram of positioning pin positioning accuracy monitoring

[0051] Figure 2 Framework diagram of online monitoring system for positioning pin positioning accuracy

[0052] Figure 3 Workflow diagram of online monitoring of positioning pin positioning accuracy DETAILED DESCRIPTION

[0053] The horizontal position and diameter change of the positioning pin are monitored in real time by using the parallel irradiation of the laser. Figure 1 As shown. The solution is mainly composed of lasers and CCD sensors. The laser uses a point laser that can emit a collimated spot with a diameter of 2mm and a wavelength of 650um. The CCD sensor uses Toshiba TCD1304. The photosensitive area is arranged with 3648 pixels. The pixel size is 8um×200um. The measurement resolution can reach 0.008mm. It can sense wavelengths of 300nm to 1100nm. The maximum laser sensitive measurement range is 0mm to 29.1mm. During monitoring, the laser and CCD sensor need to be installed on both sides of the measured positioning pin respectively, which will not affect the loading and unloading of the welded parts and can be fixedly installed for a long time. The laser is controlled to emit laser, and the center of the laser is exactly at the same height as the outer surface of the locating pin. The laser irradiation area on the outer surface of the locating pin is blocked, and the laser passes through the un-irradiated area normally and hits the CCD sensor on the other side. The position of the laser edge on the CCD sensor can be obtained based on the collected CCD sensitive data; when the outer surface of the locating pin is worn or offset, the position of the laser edge on the CCD sensor will change, and then the horizontal position and diameter change of the locating pin can be measured to realize the monitoring of the locating pin positioning accuracy.

[0054] In order to realize the online monitoring of the positioning accuracy of the positioning pin, the main control box is used to connect the laser and CCD sensor to form an online monitoring system for the positioning accuracy of the positioning pin, which can monitor the positioning accuracy in real time. The monitoring system framework is as follows: Figure 2 As shown. The laser is controlled to emit laser light, and sensitive laser data on the CCD sensor is collected to calculate the horizontal position and diameter change of the positioning pin in real time. The measurement frequency of 1 time / minute can be achieved, which is significantly higher than the traditional manual measurement frequency of once every few months, and online monitoring can be realized.

[0055] The specific monitoring process of the present invention is as follows Figure 3 Shown

[0056] (1) Initial installation: Adjust the laser beam to the same height as the outer surface of the positioning pin. The laser beam irradiates the outer surface of the positioning pin. Install the sensor horizontally so that its photosensitive surface is perpendicular to the laser beam. Adjust the horizontal position of the laser and the sensor to ensure that they do not affect the loading and unloading of the weldment.

[0057] (2) Perform initial measurement: The main control box controls two sets of monitors to monitor the outer surface of the positioning pin in two directions, collect laser data, smooth the data, and use the processed data edge as the laser irradiation edge. Record the position x0 of the lower edge of the laser irradiation area on sensor 1; the position x1 of the upper edge; record the position y0 of the right edge of the laser irradiation area of ​​sensor 2; the position y1 of the left edge;

[0058] (3) Calculate the initial position of the positioning pin in the x direction:

[0059] H x =(x0+x1) / 2 (14)

[0060] Diameter in the x-direction:

[0061] D x =x0-x1 (15)

[0062] Initial position in the y direction:

[0063] H y =(y0+y1) / 2 (16)

[0064] Diameter in the y direction:

[0065] D y =y0-y1 (17)

[0066] Initial diameter of dowel pin:

[0067] D0=(D x +D y ) / 2 (18)

[0068] (4) After initialization is completed, enter real-time monitoring with a frequency of 1 time / minute.

[0069] (5) During monitoring, the main control box controls the laser to illuminate the outer surface of the positioning pin in parallel, collects laser data on the sensor, and calculates the position x2 and the upper edge position x3 of the laser beam of sensor 1; the right edge position y2 and the left edge position y3 of the laser beam of sensor 2;

[0070] (6) Calculate the current position of the positioning pin in the x direction:

[0071] H' x =(x2+x3) / 2 (19)

[0072] Diameter in x direction:

[0073] D x =x2-x3 (20)

[0074] Current position in the y direction:

[0075] H' y =(y2+y3) / 2 (21)

[0076] Diameter in the y direction:

[0077] D' y =y2-y3 (22)

[0078] Current diameter of dowel pin:

[0079] D1=(D' x +D' y ) / 2 (23)

[0080] Horizontal position in the x direction:

[0081] ΔH x =H' x -H x (twenty four)

[0082] Horizontal position in the y direction:

[0083] ΔH y =H' y -H y (25)

[0084] Change in locating pin diameter:

[0085] ΔD=D1-D0 (26)

[0086] (7) Output the horizontal position and diameter change of the positioning pin, and determine whether it exceeds the error range. If it exceeds the error range, an alarm is triggered to achieve online monitoring of the positioning accuracy of the positioning pin.

[0087] (8) After completing the measurement, turn off the laser through the main control box and wait for the next monitoring.

[0088] (9) In order to verify the accuracy and stability of the method of the present invention, the positioning accuracy of the simulated locating pins of the outer diameter calibration rods with a diameter of 20.3 mm and a thickness of 20.5 mm were monitored online. The output data of the horizontal displacement of the outer diameter calibration rod are shown in Table 1, and the output data of the diameter change of the outer diameter calibration rod are shown in Table 2. The mean square error of the horizontal position of the outer diameter calibration rod is 0.0082 mm, and the mean square error of the diameter change of the outer diameter calibration rod is 0.0179 mm, which meets the monitoring accuracy requirements.

[0089] Table 1 Horizontal positioning accuracy error of the outer diameter calibration rod

[0090]

[0091] Table 2 Positioning accuracy error of outer diameter calibration rod diameter

[0092]

[0093] The non-contact online monitoring method for positioning pin positioning accuracy provided by the present invention effectively solves the accuracy and real-time problems in traditional monitoring methods, and provides a strong guarantee for realizing high-precision welding technology.

[0094] The contents not described in detail in this specification belong to the prior art known to the professionals in this field.

Claims

1. A method for online monitoring of the positioning accuracy of a welding fixture positioning pin, characterized in that Two lasers and one sensor form a group of monitors. Two laser beams in the same group of monitors are parallelly irradiated to the sensor. The two groups of monitors are installed vertically in the same horizontal plane with the outer surface of the positioning pin as the reference. The laser irradiation direction of one group of monitors is used as the x monitoring direction, and the other group is used as the y monitoring direction. The laser beam irradiates the outer surface of the positioning pin and projects it to the sensor. According to the laser sensitive data received by the sensor, the edge position of the beam blocked by the positioning pin and the diameter of the positioning pin are calculated to realize the online monitoring of the positioning accuracy of the positioning pin. The specific steps include: (1) Initial installation: adjust the laser beam to the same height as the outer surface of the positioning pin, irradiate the outer surface of the positioning pin with the laser beam, adjust the photosensitive surface to be perpendicular to the laser beam, and adjust the horizontal position of the laser and the sensor to ensure that the loading and unloading of the welded parts are not affected; (2) Perform initialization measurement: Measure the outer surface of the positioning pin once, record the position x0 of the lower edge of the laser irradiation area on sensor 1, and the position x1 of the upper edge; record the position y0 of the right edge of the laser irradiation area on sensor 2, and the position y1 of the left edge; (3) Calculate the initial position of the positioning pin in the x direction: H x =(x0+x1) / 2 (1) Diameter in x direction: D x =x0-x1 (2) Initial position in the y direction: H y =(y0+y1) / 2 (3) Diameter in the y direction: D y =y0-y1 (4) Initial diameter of dowel pin: D0=(D x +D y ) / 2 (5) (4) After initialization is completed, enter real-time monitoring with a frequency of 1 time / minute; (5) During monitoring, the main control box controls the laser to illuminate the outer surface of the positioning pin in parallel, collects laser data on the sensor, and calculates the position x2 and the upper edge position x3 of the laser beam of sensor 1; the right edge position y2 and the left edge position y3 of the laser beam of sensor 2; (6) Calculate the current position of the positioning pin in the x direction: H' x =(x2+x3) / 2 (6) Diameter in x direction: D x =x2-x3 (7) Current position in the y direction: <h2 style=";text-align:left;direction:ltr">H'<h2 style=";text-align:left;direction:ltr"> y <h2 style=";text-align:left;direction:ltr"> (y2+y3) / 2 (8) Diameter in the y direction: <h2 style=";text-align:left;direction:ltr">D'<h2 style=";text-align:left;direction:ltr"> y <h2 style=";text-align:left;direction:ltr"> =y2-y3 (9) Current diameter of dowel pin: D1=(D' x +D' y ) / 2 (10) Horizontal position in the x direction: ΔH x =H' x -H x (11) Horizontal position in the y direction: ΔH y =H' y -H y (12) Change in locating pin diameter: ΔD=D1-D0 (13) (7) Output the horizontal position and diameter change of the positioning pin to achieve online monitoring of the positioning accuracy of the positioning pin.

2. The method for online monitoring of the positioning accuracy of the positioning pin of a welding tool according to claim 1 is characterized in that The main control box can control two groups of monitors at the same time. It has internally integrated data processing and data analysis modules and can adjust the monitoring frequency according to actual needs.

3. The method for online monitoring of the positioning accuracy of the positioning pin of a welding tool according to claim 1 is characterized in that In the measurement of the positioning accuracy of the locating pins of welding fixtures, the sensor is installed horizontally for laser detection.

4. The method for online monitoring of the positioning accuracy of the positioning pin of a welding tool according to claim 1 is characterized in that The horizontal position and diameter change of the positioning pin after each measurement are analyzed, and an alarm will be triggered if the error range is exceeded.

5. The method for online monitoring of the positioning accuracy of the positioning pin of a welding tool according to claim 1 is further characterized by: The collected sensitive laser data is smoothed, and a gradient threshold is set for the smoothed data to eliminate small gradients and use the index value of the maximum gradient as the laser irradiation edge.

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