CN-121589723-B - Dynamic error control method of precision grinding machine considering diameter of grinding wheel

Abstract

The application relates to the technical field of grinding machine error control, in particular to a dynamic error control method of a precision grinding machine taking the diameter of a grinding wheel into consideration, which comprises the steps of collecting a grinding wheel surface image in the grinding machine and converting the grinding wheel surface image into a color space; the method comprises the steps of screening non-spark pixel points in a color space according to color characteristics of sparks generated by a grinding wheel during grinding of a grinding machine to obtain a first pixel point set, removing pixel points belonging to parts of the grinding machine from the first pixel point set based on brightness differences of the non-spark pixel points to obtain a second pixel point set, extracting all circular contours in the second pixel point set through geometric features of the pixel points in the second pixel point set, obtaining confidence coefficients of all the circular contours, determining true contours of the grinding wheel in an image, obtaining diameters of the true contours of the grinding wheel, and calculating and adjusting rotating speed of the grinding wheel to control dynamic errors of the grinding machine. The application improves the control precision of the dynamic error of the grinding machine.

Inventors

• Zhou Kuanzhong
• ZHU GANG
• HE HAILUN

Assignees

• 宁波固高智能科技有限公司

Dates

Publication Date

20260508

Application Date

20260129

Claims (7)

1. 1. The dynamic error control method of the precision grinding machine considering the diameter of the grinding wheel is characterized by comprising the following steps: acquiring a grinding wheel surface image in a grinding machine, and converting the grinding wheel surface image into a Lab color space; Screening non-spark pixel points in a color space according to the color characteristics of sparks generated by a grinding wheel during grinding processing of a grinding machine to obtain a first pixel point set; removing pixels belonging to the grinding machine parts from the first pixel set based on the brightness difference of the non-spark pixels to obtain a second pixel set; Extracting each circular contour in the second pixel point set through the geometric features of the pixel points in the second pixel point set, analyzing the discrete degree of the gray values of the pixel points on each circular contour and the integral distribution of the brightness values of the pixel points, and acquiring the confidence coefficient of each circular contour to be used for determining the real contour of the grinding wheel in the image; The diameter of the real outline of the grinding wheel is obtained, and the rotating speed of the grinding wheel is calculated and adjusted so as to control the dynamic error of the grinding machine; the method comprises the steps of carrying out negative correlation mapping on the discrete degree to obtain color characteristic values of all circular outlines, taking the average value of brightness values of all pixel points L on all the circular outlines as the brightness characteristic value of each circular outline, combining the brightness characteristic value and the color characteristic value to determine the confidence coefficient of each circular outline, and carrying out positive correlation on the confidence coefficient of each circular outline, the brightness characteristic value and the color characteristic value.
2. 2. The method for controlling dynamic errors of a precision grinding machine taking account of a diameter of a grinding wheel as claimed in claim 1, wherein said obtaining a first set of pixels comprises: Threshold segmentation is carried out on a chromaticity value of all pixel points in the grinding wheel surface image, and the pixel points with a chromaticity value smaller than the segmentation threshold value are used as non-spark pixel points to form a first pixel point set.
3. 3. The method for controlling dynamic error of precision grinding machine taking account of diameter of grinding wheel as defined in claim 2, wherein said obtaining the second set of pixels comprises: Threshold segmentation is carried out on L brightness values of all pixel points in the first pixel point set, and all pixel points with L brightness values smaller than the segmentation threshold value form a second pixel point set.
4. 4. The method for controlling dynamic error of precision grinding machine in consideration of diameter of grinding wheel according to claim 1, wherein said extracting each circular contour in the second set of pixels comprises: And carrying out connected domain analysis on the pixels in the second pixel set, and acquiring all circular outlines in the second pixel set by using a circular detection algorithm.
5. 5. The method for controlling dynamic errors of a precision grinding machine taking account of the diameter of a grinding wheel as set forth in claim 1, wherein a circular contour with the highest confidence is used as a true contour of the grinding wheel in the image.
6. 6. The method for controlling dynamic error of precision grinding machine taking into account diameter of grinding wheel as defined in claim 5, wherein said calculating and adjusting rotational speed of the grinding wheel comprises: The diameter of the real outline of the grinding wheel in the image is converted into an actual distance, the theoretical rotating speed of the grinding wheel is calculated by combining the linear speed of the grinding wheel, and the rotating speed of the motor of the grinding wheel is adjusted to be the theoretical rotating speed.
7. 7. The method for controlling dynamic error of precision grinding machine taking into account diameter of grinding wheel as defined in claim 6, wherein said calculating theoretical rotational speed of the grinding wheel comprises: And calculating the product of the circumferential rate pi and the actual distance, wherein the theoretical rotating speed of the grinding wheel is the ratio of the linear speed of the grinding wheel to the product.

Description

Dynamic error control method of precision grinding machine considering diameter of grinding wheel Technical Field The application relates to the technical field of error control of grinding machines, in particular to a dynamic error control method of a precision grinding machine considering the diameter of a grinding wheel. Background As an important component in mechanical devices, the machining accuracy and surface quality of bearings have a decisive influence on the friction coefficient during the movement of the mechanical rotating body, whereas the machining of bearings usually depends on precision grinding machines. Among them, a grinding machine is a machine tool for grinding a surface of a workpiece using a grinding tool, and most grinding machines are grinding machines using a grinding wheel rotating at a high speed. However, in actual grinding processing of a grinding machine using a grinding wheel, the diameter of the grinding wheel is continuously reduced along with the grinding process, so that the linear speed of the grinding wheel is reduced, the grinding precision is reduced, and the grinding error of the grinding machine is difficult to meet the precision processing requirement of a bearing, therefore, the detection of the diameter of the grinding wheel is a key for ensuring the linear speed of the grinding wheel to be constant and realizing dynamic error control in the grinding processing of the precision grinding machine. With the development of machine vision technology, a grinding wheel diameter detection method based on machine vision becomes the existing common technology, and has the advantages of non-contact, real-time performance, high precision and the like. However, in the actual grinding process of a precision grinding machine, sparks generated when a grinding wheel rubs with a workpiece, contour ghosts generated when the grinding wheel rotates at a high speed, and shielding of parts in a picture of the grinding machine shot by a camera can cause inaccurate positions of contour edges of the grinding wheel detected from an acquired grinding wheel image, so that deviation occurs in detection results of the diameter of the grinding wheel, and the control accuracy of dynamic errors in the grinding process of the grinding machine is affected. Disclosure of Invention In order to solve the technical problems, the application provides a dynamic error control method of a precision grinding machine considering the diameter of a grinding wheel, so as to solve the existing problems. The dynamic error control method of the precision grinding machine considering the diameter of the grinding wheel adopts the following technical scheme: one embodiment of the application provides a method for controlling dynamic errors of a precision grinding machine taking the diameter of a grinding wheel into consideration, which comprises the following steps: acquiring a grinding wheel surface image in a grinding machine and converting the grinding wheel surface image into a color space; Screening non-spark pixel points in a color space according to the color characteristics of sparks generated by a grinding wheel during grinding processing of a grinding machine to obtain a first pixel point set; removing pixels belonging to the grinding machine parts from the first pixel set based on the brightness difference of the non-spark pixels to obtain a second pixel set; Extracting each circular contour in the second pixel point set through the geometric features of the pixel points in the second pixel point set, analyzing the discrete degree of the gray values of the pixel points on each circular contour and the integral distribution of the brightness values of the pixel points, and acquiring the confidence coefficient of each circular contour to be used for determining the real contour of the grinding wheel in the image; The diameter of the real outline of the grinding wheel is obtained, and the rotating speed of the grinding wheel is calculated and adjusted so as to control the dynamic error of the grinding machine. In one embodiment, the wheel surface image is converted to Lab color space. In one embodiment, the obtaining the first set of pixel points includes: Threshold segmentation is carried out on a chromaticity value of all pixel points in the grinding wheel surface image, and the pixel points with a chromaticity value smaller than the segmentation threshold value are used as non-spark pixel points to form a first pixel point set. In one embodiment, the obtaining the second set of pixel points includes: Threshold segmentation is carried out on L brightness values of all pixel points in the first pixel point set, and all pixel points with L brightness values smaller than the segmentation threshold value form a second pixel point set. In one embodiment, the extracting each circular contour in the second set of pixels includes: And carrying out connected domain analysis on the pixels in the second pixel set, an