Automatic optical cylinder inner diameter measuring method

Abstract

The invention provides an automatic optical cylinder inner diameter measuring method. The method comprises the following steps that S1, a cylinder to be measured is fixed to a measuring platform; s2, two point lasers are arranged to be aligned with the inner wall of the cylinder; s3, controlling a laser to emit laser and receive a reflection signal through an automatic system; s4, calculating the distance between the two points according to a laser ranging principle; and S5, calculating the inner diameter of the cylinder through the geometrical relationship. Through double-point laser measurement and geometric calculation, cylinder inner diameter data can be accurately obtained, the measurement process is controlled through an automatic system, the measurement efficiency is greatly improved, and the requirement for large-batch production is met.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, specifically to an automated optical cylinder inner diameter measurement method, and more particularly to an automated optical cylinder inner diameter measurement method that utilizes optical principles and automation technology to achieve high-precision measurement of cylinder inner diameter. Background Technology

[0002] In modern manufacturing, measuring the inner diameter of cylindrical parts is a crucial aspect of quality control. Traditional methods for measuring inner diameter, such as using calipers, micrometers, or plug gauges, while simple to operate, have significant limitations in accuracy and efficiency, and are difficult to automate. With the development of Industry 4.0 and intelligent manufacturing, the demand for high-precision, automated measurement technologies is increasing.

[0003] In recent years, optical measurement technology has been increasingly applied to the field of internal diameter measurement due to its non-contact, high precision, and high efficiency. For example, laser ranging technology can accurately calculate distances by measuring laser reflection time. However, most existing optical measurement methods are designed for measuring the outer diameter or the internal diameter of simple shapes, and measuring the internal diameter of complex structures (such as multi-layered thick-walled cylinders) still faces challenges. In addition, traditional optical measurement often relies on manual operation, which is inefficient and cannot meet the needs of mass production.

[0004] Patent document CN119756271A discloses a fixture for measuring the inner and outer diameters of easily deformable thin-walled cylindrical parts. It uses an inflatable airbag to fit against the thin-walled cylinder being measured. Because the pressure on the contact surface is equal everywhere, the thin-walled cylinder is subjected to uniform force, which corrects the deformation of the thin-walled cylinder caused by transportation, storage or other reasons. The sliding measuring rod is equipped with an outer diameter measuring device, an inner diameter measuring device and an axial measuring device to measure the outer diameter, inner diameter and corresponding vertical distance of the thin-walled cylinder being measured, respectively. However, this fixture is not suitable for measuring the inner diameter of complex structures.

[0005] Therefore, in view of the shortcomings of existing technologies, there is an urgent need for an automated optical cylinder inner diameter measurement method that can solve the problems of low accuracy and low efficiency in inner diameter measurement and the difficulty in measuring the thickness of multiple layers of walls. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide an automated method for measuring the inner diameter of an optical cylinder.

[0007] The automated optical cylinder inner diameter measurement method provided by the present invention includes the following steps: S1: Fix the cylinder to be measured onto the measuring platform; S2: Set two point lasers to align with the inner wall of the cylinder; S3: The laser emits laser light and receives reflected signals through an automated system; S4: Calculate the distance between two points based on the principle of laser ranging; S5: Calculate the inner diameter of the cylinder using geometric relationships.

[0008] Preferably, in S1, a cylindrical clamp is provided on the measuring platform, and the cylindrical clamp is configured to adjust the clamping force according to the size of the cylinder.

[0009] Preferably, in S2, the two point lasers are installed on the same cross section inside the cylinder, and the line connecting the two point lasers passes through the center of the cylinder. The laser beams emitted by the two point lasers remain parallel and perpendicular to the line connecting the two point lasers.

[0010] Preferably, in step S3, the automation system includes a laser controller and a data acquisition module. The laser controller is used to control the emission time and frequency of the laser, and the data acquisition module is used to record the time difference of the reflected signal in real time.

[0011] Preferably, in S4, the distance from the laser to the inner wall of the cylinder is calculated by measuring the time difference between laser emission and reception, combined with the speed of light; The calculation formula is: Distance = (Time difference × Speed ​​of light) / 2.

[0012] Preferably, in S5, the inner diameter D of the cylinder is calculated using the cosine theorem based on the known fixed distance L between the two lasers and the distances d1 and d2 from each laser to the inner wall of the cylinder. According to geometric relationships: +

[0013] +

[0014] =L in, Let be the distance between one of the lasers and the center of the cylinder. The distance between the other laser and the center of the cylinder; The final calculation formula is as follows: .

[0015] Preferably, the method further includes step S6: performing error analysis and correction on the measurement data. By statistically analyzing multiple measurement results, systematic errors are identified, and a correction algorithm is used to improve measurement accuracy.

[0016] Preferably, in S6, the method of taking the average value of multiple measurements is adopted, and the interval between each measurement is consistent.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses a dual-point laser for measurement and geometric calculation to accurately obtain the inner diameter data of a cylinder. Furthermore, the measurement process is controlled by an automated system, which greatly improves measurement efficiency and meets the needs of mass production.

[0018] 2. This invention is applicable to the inner diameter measurement of multi-layer thick-walled cylinders. Traditional methods suffer from problems such as large contact measurement errors, high deformation risk, and poor adaptability. This method uses non-contact measurement, mathematical methods to calculate the inner diameter, and adaptive fixture design, which breaks through the limitations of traditional methods and expands the application scenarios.

[0019] 3. This invention ensures stable and reliable measurement results by performing error analysis and correction, meeting industrial standard requirements. Attached Figure Description

[0020] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall measurement process of the present invention; Figure 2 This is a schematic diagram of the assembly of the point laser and the cylindrical component in this invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0022] This invention discloses an automated optical cylinder inner diameter measurement method. By using a dual-point laser for measurement and geometric calculation, the inner diameter data of the cylinder can be accurately obtained. Furthermore, the measurement process is controlled by an automated system, which greatly improves the measurement efficiency and meets the needs of mass production. Moreover, this invention uses non-contact measurement and mathematical methods to calculate the inner diameter, making it applicable to the inner diameter measurement of multi-layer thick-walled cylinders.

[0023] The automated optical cylinder inner diameter measurement method provided by the present invention, such as Figure 1 As shown, it includes the following steps: S1: Fix the cylinder to be measured onto the measuring platform; S2: Set two point lasers to align with the inner wall of the cylinder; S3: The laser emits laser light and receives reflected signals through an automated system; S4: Calculate the distance between two points based on the principle of laser ranging; S5: Calculate the inner diameter of the cylinder using geometric relationships.

[0024] In step S1, the measuring platform is equipped with a special fixture that can firmly fix the cylinder to be measured, ensuring that the position of the cylinder remains stable during the measurement process. The special fixture adopts an adjustable V-block or three-jaw chuck structure, which is suitable for cylindrical workpieces of different diameters, and is equipped with a horizontal calibration device to ensure that the cylinder axis is parallel to the measuring reference plane. Preferably, the special fixture is equipped with a pressure sensor to monitor the clamping force in real time, avoiding over-clamping that could cause cylinder deformation or insufficient clamping force that could cause workpiece displacement during the measurement process.

[0025] In step S2, two point lasers are installed on the same cross-section inside the cylinder, and the line connecting the two point lasers passes through the center of the cylinder. The laser beams emitted by the two point lasers are kept parallel and perpendicular to the line connecting the two point lasers to ensure the accuracy of the measurement data. The point lasers are installed using a high-precision translation slide, which can adjust their relative positions to adapt to the measurement requirements of different diameters. The angle between the laser beam and the normal direction of the inner wall of the cylinder is no greater than 5° to reduce the impact of the incident angle deviation on the ranging accuracy.

[0026] In step S3, the automated system includes a laser controller and a data acquisition module, capable of precisely controlling the laser emission time and receiving the reflected signal in real time. The laser controller drives the laser using pulse modulation, with a timing control accuracy of 1 ns. The data acquisition module includes a photoelectric converter and a high-speed time-to-digital converter, capable of recording the laser flight time at a sampling rate of 100 MHz, used to record the time difference of the reflected signal in real time. In step S4, the distance from the laser to the inner wall of the cylinder is calculated by measuring the time difference from laser emission to reception and combining it with the speed of light. The calculation formula is: Distance = (Time difference × Speed ​​of light) / 2.

[0027] In step S5, the inner diameter D of the cylinder is calculated using the known fixed distance L between the two lasers and the distances d1 and d2 from each laser to the inner wall of the cylinder. According to geometric relationships: +

[0028] +

[0029] =L in, Let be the distance between one of the lasers and the center of the cylinder. The distance between the other laser and the center of the cylinder; The final calculation formula is as follows: This method is applicable to the measurement of the inner diameter of multi-layer thick-walled cylinders. By adjusting the laser wavelength or using a penetrating laser, it is possible to penetrate the outer wall thickness to measure the inner diameter of the inner layer.

[0030] This invention achieves automated, high-precision measurement of the inner diameter of a cylinder based on the principle of combining non-contact optical measurement with spatial geometric analysis. The system uses two parallel point lasers to emit laser light towards the inner wall of the cylinder, and utilizes the laser triangulation method to measure the distance from the sensor to the inner wall surface in real time. A stable geometric relationship is formed between the fixed baseline formed by the two lasers and the measured inner wall. The center position and radius are calculated using spatial analysis methods, thereby determining the inner diameter. For multi-layered thick structures, the system uses a laser beam of a specific wavelength to penetrate the outer layer material, directly acquiring the reflected signal from the inner layer surface, and separating the measurement data of each layer through signal processing technology. The entire measurement process is coordinated by an automated control system, including automatic workpiece positioning, multi-section scanning measurement, real-time environmental parameter compensation, and intelligent data processing, ultimately outputting accurate inner diameter dimensions and their morphological parameters, effectively overcoming the limitations of low efficiency and poor applicability of traditional contact-based measurements.

[0031] In a preferred embodiment, the above method further includes step S6, which involves error analysis and correction of the measurement data to further improve the measurement accuracy. In step S6, multiple measurements are taken and the average value is calculated to reduce the impact of random errors on the measurement results. The system automatically performs 5-10 consecutive measurements, and after eliminating gross errors, the arithmetic mean is taken as the final result. The measurement interval is dynamically adjusted according to the thermal deformation characteristics to ensure that the measurement data are independent of each other.

[0032] The above methods achieve fully automated operation through preset programs, which can automatically complete the measurement process, reduce manual intervention, and improve measurement efficiency. The system integrates a human-machine interface, which supports measurement parameter setting, real-time data display, historical record query, and measurement report export functions. It is also equipped with an industrial Ethernet interface, which can communicate with the host computer management system to realize network management of measurement data.

[0033] Example 1: This embodiment provides an automated optical cylinder inner diameter measurement method. The measurement platform is a high-precision marble measuring platform with dimensions of 1500mm × 800mm × 200mm and a flatness error of no more than 0.01mm / m. The platform is equipped with a T-slot array for mounting various functional modules. The dedicated clamping system includes a servo motor-driven three-jaw self-centering chuck with a diameter of 200mm and a maximum clamping range of 20-300mm. The clamp can be adjusted in three directions (XYZ) with an accuracy of 0.01mm. The laser measurement unit includes a point laser displacement sensor with a measurement range of 10-500mm, a resolution of 0.001mm, and a repeatability of 0.002mm. The control system uses an industrial computer as the main controller and is equipped with a multi-axis motion control card, a data acquisition card, and a laser control module. The motion control card controls the rotation and positioning of the clamp, and the data acquisition card acquires laser ranging data at a sampling rate of 100kHz.

[0034] Furthermore, the multi-layer thick metal cylinder is placed in the center of the three-jaw pneumatic clamp on the measuring platform. The clamp is started by industrial computer control, and the clamping force is automatically adjusted according to the outer diameter of the cylinder. After clamping, it is held for 5 seconds to ensure that the cylinder and the clamp are tightly fitted and without displacement.

[0035] Furthermore, a micrometer is used to measure the gap between the two ends of the cylinder and the clamp to ensure that the gap is ≤0.02mm; at the same time, the coaxiality between the cylinder axis and the platform baseline is detected by the displacement sensor built into the platform. If the coaxiality error is >0.05mm, the clamp position is finely adjusted to correct it until the coaxiality meets the requirements.

[0036] Furthermore, the control system drives the chuck to rotate to a specified angle position. The laser controller sends a trigger signal, and the two lasers synchronously emit laser pulses with a pulse width of 10 ns. The photodetector receives the reflected signal, and the time-to-digital converter measures the laser flight time with a measurement accuracy of 0.1 ps. During laser emission, the laser controller accurately records the emission time of each laser, and the data acquisition module receives the reflected laser signal in real time and records the reception time of the reflected signal. Data is continuously collected 10 times at each measurement point, and the system automatically removes gross errors and takes the average value.

[0037] After collecting sufficient data, wavelet filtering is applied to the time data to eliminate noise interference. Based on the law of cosines, each set of valid data is substituted into the formula to calculate the corresponding inner diameter value. The system employs multiple error compensation strategies: a temperature-deformation model is established to compensate for temperature variations in the measurement results; systematic errors caused by workpiece installation eccentricity are eliminated through mathematical modeling; piecewise linear interpolation is used to compensate for the nonlinear errors of the laser; and an adaptive filtering algorithm is employed to eliminate environmental interference such as vibration.

[0038] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0039] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An automated method for measuring the inner diameter of an optical cylinder, characterized in that, Includes the following steps: S1: Fix the cylinder to be measured onto the measuring platform; S2: Set two point lasers to align with the inner wall of the cylinder; S3: The laser emits laser light and receives reflected signals through an automated system; S4: Calculate the distance between two points based on the principle of laser ranging; S5: Calculate the inner diameter of the cylinder using geometric relationships.

2. The automated optical cylinder inner diameter measurement method according to claim 1, characterized in that, In S1, a cylindrical clamp is provided on the measuring platform, and the cylindrical clamp is configured to adjust the clamping force according to the size of the cylinder.

3. The automated optical cylinder inner diameter measurement method according to claim 1, characterized in that, In S2, two point lasers are installed on the same cross section inside the cylinder, and the line connecting the two point lasers passes through the center of the cylinder. The laser beams emitted by the two point lasers remain parallel and perpendicular to the line connecting the two point lasers.

4. The automated optical cylinder inner diameter measurement method according to claim 1, characterized in that, In S3, the automation system includes a laser controller and a data acquisition module. The laser controller is used to control the emission time and frequency of the laser, and the data acquisition module is used to record the time difference of the reflected signal in real time.

5. The automated optical cylinder inner diameter measurement method according to claim 3, characterized in that, In S4, the distance from the laser to the inner wall of the cylinder is calculated by measuring the time difference between laser emission and reception and combining it with the speed of light. The calculation formula is: Distance = (Time difference × Speed ​​of light) / 2.

6. The automated optical cylinder inner diameter measurement method according to claim 5, characterized in that, In S5, the inner diameter D of the cylinder is calculated using the cosine theorem, based on the known fixed distance L between the two lasers and the distances d1 and d2 from each laser to the inner wall of the cylinder. According to geometric relationships: + + =L in, Let be the distance between one of the lasers and the center of the cylinder. The distance between the other laser and the center of the cylinder; The final calculation formula is as follows: .

7. The automated optical cylinder inner diameter measurement method according to claim 1, characterized in that, It also includes S6: performing error analysis and correction on the measurement data, identifying systematic errors through statistical analysis of multiple measurement results, and using correction algorithms to improve measurement accuracy.

8. The automated optical cylinder inner diameter measurement method according to claim 7, characterized in that, In S6, the method of taking the average value of multiple measurements is adopted, and the time interval between each measurement is consistent.

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