A large gear measuring device based on machine vision and its measuring method

Abstract

The present invention relates to the field of large gear error measurement, and discloses a large gear measuring device based on machine vision and its measuring method. It includes: a main body column of the machine, a corner measurement reference plate, a binocular vision measurement mechanism, a meshing line displacement measurement mechanism, and motion control and signal processing software. The device of the present invention can quickly measure the tooth profile deviation of a large gear. Through the corner measurement reference plate fixed on the large gear and the binocular vision measurement mechanism, the corner of the large gear is measured with high precision; through the meshing line displacement measurement mechanism, the displacement in the meshing line direction of the large gear is obtained; through the ratio relationship between the corner of the large gear and the meshing line displacement, the tooth profile deviation of the large gear is obtained, and finally the measurement results are calculated and analyzed by software to complete the high-precision measurement of the tooth profile deviation of the large gear to be measured.

Description

Technical Field

[0001] The present invention relates to the field of large gear error measurement, and particularly to a large gear measurement device and a measurement method based on machine vision. Background Art

[0002] Large gears are key components of large-scale equipment, widely used in industries such as heavy machinery, large ships, oil extraction, and aerospace, playing an important role in the national economy. However, due to their complex structure and continuously increasing processing accuracy requirements, their measurement has always been a technical challenge.

[0003] The invention patent [CN200810013124.8] discloses an in-machine measuring instrument for measuring large gear deviations with a flank rack probe, proposing an in-machine measurement scheme for measuring tooth profile deviations with a rack-type flank probe, and using a friction disc measurement method to obtain the rotation angle of the large gear. However, the method of obtaining the rotation angle of the large gear through the friction disc is prone to slipping, and the measurement radius of the circular grating measurement method is too large, both of which will cause the rotation angle error and cannot ensure high-precision measurement.

[0004] The invention patent [CN200910084275.7] discloses a large gear measurement method based on laser tracking technology. Using the large space measurement ability of a laser tracker to position a super-large gear and a three-dimensional measurement platform, and using the laser tracker coordinate system as an intermediary to achieve the positioning between the super-large gear and the three-dimensional measurement platform. Finally, using the three-dimensional measurement platform to measure various errors of the super-large gear according to the conventional gear measurement method. Due to the use of a laser tracker, the instrument is expensive, and at the same time, due to the accuracy problem of the laser tracker itself, high-precision measurement cannot be achieved.

[0005] The invention patent [CN201510034109.1] discloses a double-arm super-large gear measuring instrument and its measurement method, which realizes overall evaluation of segmented measurement through local positioning and local evaluation, or point cloud matching after segmented measurement. Although the method of "measuring large by small" is also adopted, the problem of measurement accuracy is not mentioned. Summary of the Invention

[0006] The present invention aims at the defects existing in the prior art and provides a large gear measurement device and a measurement method based on machine vision.

[0007] The rotation angle measurement reference plate is placed on the large gear to be measured. As the large gear rotates, the binocular vision measurement mechanism continuously takes pictures of the rotation angle measurement reference plate to achieve high-precision measurement of the rotation angle of the large gear. According to the measurement principle of the gear meshing method, a tooth profile probe is used to engage with the tooth profile of the large gear to measure the linear displacement of the tooth profile probe, and then the displacement in the normal direction of the tooth profile is obtained. Through the ratio relationship between the rotation angle of the large gear and the displacement in the normal direction of the tooth profile, high-precision measurement of the tooth profile of the large gear is completed.

[0008] To achieve the above object, the present invention adopts the following technical solutions, including the main body column of the machine, the corner measurement reference plate, the binocular vision measurement mechanism, the meshing line displacement measurement mechanism, and the motion control and signal processing software; characterized in that the corner measurement reference plate is placed on the large gear to be measured and rotates with the large gear; the binocular vision measurement mechanism is connected to the upper end of the main body column of the machine and is placed directly above the measurement reference plate; the meshing line displacement measurement mechanism is connected to the side of the main body column of the machine (placed near the tooth top of the large gear).

[0009] Further, the meshing line displacement measurement mechanism includes a measurement workbench, a probe movement and measurement mechanism, a measurement contact force control mechanism, a limit device, and a Z-direction motion module; the probe movement and measurement mechanism, the measurement contact force control mechanism, and the limit device are all placed above the measurement workbench. The measurement workbench is connected to the measurement workbench stiffener and fixed on the Z-direction motion module to realize the Z-direction movement of the measurement workbench.

[0010] Further, the probe movement and measurement mechanism includes a linear measurement guide rail, an upper slider plate, a tooth profile probe, a grating scale displacement sensor, and a grating connecting piece; the linear measurement guide rail is connected to the measurement workbench, and the two linear measurement guide rails on both sides are symmetric about the symmetry axis of the measurement workbench and the included angle is within the range of 130° ± 20°. The grating scale displacement sensor is parallel to the linear measurement guide rail. The tooth profile probe is fixed above the upper slider plate. The upper slider plate is connected to the linear measurement guide rail, and the side of the upper slider plate is connected to the grating scale reading head through the grating connecting piece.

[0011] Further, the measurement contact force control mechanism includes a fixed pulley assembly, a weight, a weight guiding cylinder, and a connecting line; one end of the connecting line is connected to the upper slider plate, and the other end is connected to the weight through the fixed pulley assembly. The weight is placed in the weight guiding cylinder, and the mass of the weight is determined according to the measurement contact force.

[0012] Further, the measurement locking mechanism includes a cylindrical locking column and a locking bolt. When measuring the left tooth profile deviation, the left upper slider plate is slid to the cylindrical locking column at the rightmost end of the linear measurement guide rail, and the upper slider plate is fixed with the locking bolt. When measuring the right tooth profile deviation, the right upper slider plate is slid to the cylindrical locking column at the leftmost end of the linear measurement guide rail, and the upper slider plate is fixed with the locking bolt.

[0013] Further, during the measurement process, the probe slides from the tooth root of the gear to be measured to near the tooth top. The grating scale displacement sensor records the moving distance L i , and immediately triggers the camera system in the binocular vision measurement mechanism when the grating scale displacement sensor moves, and continuously takes pictures of the measurement reference plate, so as to obtain the rotation angle value θ of the large gear i , substituting the corresponding parameters into formulas (1) and (2), the total deviation value of the large gear tooth profile can be solved.

[0014]

[0015] F α =max(ΔF αi )-min(ΔF αi ) (2).

[0016] Where, ΔF αi Tooth profile deviation value, α is the pressure angle of the large gear being measured, is the angle between the two linear measuring guide rails, i is the number of measurement records, i = 1, 2, 3..., n. The total deviation of the tooth profile of the large gear being measured can be calculated by formula (2), where F α is the total tooth profile deviation, max(ΔF αi ) is the maximum tooth profile deviation value, min(ΔF αi ) is the maximum tooth profile deviation value.

[0017] Compared with the prior art, the present invention has beneficial effects.

[0018] 1. The large gear measuring device based on machine vision provided by the present invention has the advantages of simple structure and operation, high measurement accuracy, etc. The measurement accuracy reaches the micron level, which can meet the 7-level precision measurement requirements of large gears with a diameter of more than 2 meters.

[0019] 2. The present invention combines visual measurement technology and innovatively proposes a binocular measurement method to complete the large gear tooth profile measurement, breaking the limitations of expensive measuring equipment and cumbersome measuring process in traditional measurement methods. Under the same measurement conditions, it can effectively improve the large gear detection accuracy and measurement efficiency.

[0020] 3. The meshing line displacement measurement mechanism of the present invention adopts a double tooth profile probe design, which can measure the left and right tooth profiles of the large gear respectively, shortening the tooth profile measurement cycle. Within the range of 130°±20°, this method shortens the size of the tooth profile on-machine measuring guide rail and greatly reduces the size of the large gear on-machine measuring device structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. The protection scope of the present invention is not limited to the following description.

[0022] Figure 1 This is a schematic diagram of on-machine measurement of a large gear measuring device based on machine vision.

[0023] Figure 2 Schematic diagram of the meshing line displacement measurement mechanism.

[0024] Figure 3 Schematic diagram of the contact force control mechanism.

[0025] Figure 4 Schematic diagram for measuring the locking mechanism.

[0026] In the figure, 1 is the large gear to be measured, 2 is the rotation angle measurement reference plate, 3 is the meshing line displacement measurement mechanism, 4 is the main body column of the machine, 5 is the motion control and signal processing software, 6 is the binocular vision measurement mechanism, 7 is the measurement workbench, 8 is the weight guide cylinder 1, 9 is the linear measurement guide rail 1, 10 is the stop block 1, 11 is the fixed pulley assembly 1, 12 is the grating scale displacement sensor 1, 13 is the tooth profile probe 1, 14 is the grating connecting piece 1, 15 is the upper plate of the slider 1, 16 is the Z-direction motion module, 17 is the grating connecting piece 2, 18 is the tooth profile probe 2, 19 is the upper plate of the slider 2, 20 is the grating scale displacement sensor 2, 21 is the fixed pulley assembly 2, 22 is the stop block 2, 23 is the linear measurement guide rail 2, 24 is the weight guide cylinder 2, 25 is the cylindrical locking column, 26 is the weight, 27 is the connecting wire, and 28 is the locking bolt. Specific implementation mode

[0027] As Figures 1-4 shown, specific embodiment: Among them, a gear with a diameter greater than 500 mm is called a large gear. It includes the main body column of the machine, the rotation angle measurement reference plate, the binocular vision measurement mechanism, the meshing line displacement measurement mechanism, and the motion control and signal processing software; characterized in that the rotation angle measurement reference plate is placed on the large gear to be measured and rotates with the large gear; the binocular vision measurement mechanism is connected to the upper end of the main body column of the machine and is placed directly above the measurement reference plate; the meshing line displacement measurement mechanism is connected to the side of the main body column of the machine and is placed near the tooth top of the large gear.

[0028] Preferably, the meshing line displacement measurement mechanism includes a measurement workbench, a probe movement and measurement mechanism, a measurement contact force control mechanism, a limiting device, and a Z-direction motion module; the probe movement and measurement mechanism, the measurement contact force control mechanism, and the limiting device are all placed above the measurement workbench. The measurement workbench is connected to the measurement workbench reinforcing rib and fixed on the Z-direction motion module to realize the Z-direction movement of the measurement workbench.

[0029] Preferably, the probe movement and measurement mechanism includes a linear measurement guide rail, an upper plate of the slider, a tooth profile probe, a grating scale displacement sensor, and a grating connecting piece; the linear measurement guide rail is connected to the measurement workbench, and the two linear measurement guide rails are symmetric about the symmetry axis of the measurement workbench and the included angle is within the range of 130° ± 20°. The grating scale displacement sensor is parallel to the linear measurement guide rail. The tooth profile probe is fixed above the upper plate of the slider. The upper plate of the slider is connected to the linear measurement guide rail. The side of the upper plate of the slider is connected to the grating reading head through the grating connecting piece.

[0030] Preferably, the measurement contact force control mechanism includes a fixed pulley assembly, a weight, a weight guiding cylinder, and a connecting line; one end of the connecting line is connected to the upper slider plate, and the other end is connected to the weight through the fixed pulley assembly. The weight is placed in the weight guiding cylinder, and the mass of the weight is determined according to the measurement contact force.

[0031] Preferably, the measurement locking mechanism includes a cylindrical locking post and a locking bolt. When measuring the left tooth profile deviation, slide the upper left slider plate to the rightmost cylindrical locking post of the linear measurement guide rail and fix the upper slider plate with the locking bolt. When measuring the right tooth profile deviation, slide the upper right slider plate to the leftmost cylindrical locking post of the linear measurement guide rail and fix the upper slider plate with the locking bolt.

[0032] Preferably, during the measurement process, the probe slides from the tooth root of the gear under test to near the tooth tip, and the grating displacement sensor records the moving distance L i , i = 1, 2, 3..., n. When the grating displacement sensor moves, it immediately triggers the camera system in the binocular vision measurement mechanism to continuously take pictures of the measurement reference plate, and the rotation angle value θ of the large gear can be obtained i , i = 1, 2, 3..., n. Substitute the corresponding parameters into equations (1) and (2) to solve the total tooth profile deviation value of the large gear.

[0033]

[0034] F α = max(ΔF αi ) - min(ΔF αi ) (2)

[0035] The working principle and process of this patent are as follows:

[0036] (1) Before the measurement starts, move the large gear measurement device based on machine vision near the large gear 1 under test. Press the inner side of the special gauge tightly against the outer tooth surface of the large gear 1 under test. After pressing the outer side of the special gauge tightly against the inner side of the measurement workbench 7, fix the large gear measurement device based on machine vision. After the measurement device is fixed, remove the special gauge. And fix the rotation angle measurement reference plate 2 to the gear 1 to be measured.

[0037] (2) Measure the left tooth profile deviation: Slide the upper second slider plate 19 to the rightmost cylindrical locking post 26 of the second linear measurement guide rail 23, fix the upper second slider plate 19 with the locking bolt 28 and fix it with bolts. Move the first probe 27 to near the tooth root of the large gear 1 under test. The first probe 27 presses against the tooth surface of the large gear 1 under test through the measurement contact force control mechanism, and the large gear 1 starts to rotate for in-machine measurement. During the measurement process, the first probe 27 slides from the tooth root of the large gear 1 under test to near the tooth tip, and the first grating displacement sensor 12 records the moving distance L of the tooth profile probe 27 through the measurement software 6 i, where \(i = 1, 2, 3, \cdots, n\). Meanwhile, the binocular vision measurement mechanism 6 continuously takes pictures of the measurement reference plate 2, and calculates the rotation angle \(\theta\) through the motion control and signal processing software 5 i For \(i = 1, 2, 3, \cdots, n\), the measuring side width probe 1 - 27 is moved by a distance \(L\) through the motion control and signal processing software 5 i and the rotation angle \(\theta\) i are calculated and processed to obtain the measurement result of the left tooth profile deviation, completing the measurement of one tooth profile.

[0038] (3) Measuring the right tooth profile deviation: Slide the upper plate 1 - 15 of the slider to the cylindrical locking post 26 at the leftmost end of the linear guide 1 - 9, and fix the upper plate 1 - 15 of the slider with the locking bolt 28; Move the probe 2 - 25 to near the tooth root of the measured large gear 1, and the probe 2 - 25 presses against the tooth surface of the measured large gear 1 through the measurement contact force control mechanism. The measured large gear 1 starts to rotate for in - machine measurement, and the measurement process is the same as that of measuring the left tooth profile.

[0039] It can be understood that the above specific description of the present invention is only for explaining the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced to achieve the same technical effect; as long as it meets the usage requirements, it is within the protection scope of the present invention.

Claims

1. A large gear measuring device based on machine vision, comprising a main body column of the machine, a corner measurement reference plate, a binocular vision measurement mechanism, a meshing line displacement measurement mechanism, and motion control and signal processing software; characterized in that, The corner measurement reference plate is placed on the large gear to be measured and rotates with the large gear; the binocular vision measurement mechanism is connected to the upper end of the main column of the machine body and is located directly above the measurement reference plate; the meshing line displacement measurement mechanism is connected to the side of the main column of the machine body; The meshing line displacement measurement mechanism includes a measurement workbench, a probe movement and measurement mechanism, a measurement contact force control mechanism, a limit device, and a Z-direction movement module; the probe movement and measurement mechanism, the measurement contact force control mechanism, and the limit device are all placed above the measurement workbench. The measurement workbench is connected to the measurement workbench stiffening rib and fixed on the Z-direction movement module to realize the Z-direction movement of the measurement workbench; The probe movement and measurement mechanism includes a linear measurement guide rail, an upper slider plate, a profile probe, a grating displacement sensor, and a grating connecting piece; the linear measurement guide rail is connected to the measurement workbench, and the two linear measurement guide rails are symmetric about the symmetry axis of the measurement workbench and the included angle is in the range of 130°±20°. The grating displacement sensor is parallel to the linear measurement guide rail. The profile probe is fixed above the upper slider plate. The upper slider plate is connected to the linear measurement guide rail, and the side of the upper slider plate is connected to the grating reading head through the grating connecting piece.

2. The large gear measuring device based on machine vision according to claim 1, characterized in that: The measurement contact force control mechanism includes a fixed pulley assembly, a weight, a weight guiding cylinder, and a connecting line; one end of the connecting line is connected to the upper plate of the slider, and the other end of the connecting line is connected to the weight through the fixed pulley assembly. The weight is placed in the weight guiding cylinder, and the mass of the weight is determined according to the measurement contact force.

3. A method for measuring large gears based on machine vision, using the large gear measuring device described in claim 2, characterized in that: The high-precision measurement of the large gear rotation angle is carried out through the binocular vision measurement mechanism and the corner measurement reference plate fixed on the large gear; the displacement in the meshing line direction of the large gear is obtained through the meshing line displacement measurement mechanism; the tooth profile deviation of the large gear is obtained through the ratio relationship between the large gear rotation angle and the meshing line displacement. Finally, the measurement results are calculated and analyzed by software to complete the high-precision measurement of the tooth profile deviation of the large gear to be measured.

4. A method for measuring large gears based on machine vision according to claim 3, characterized in that: Through the binocular vision measurement mechanism and the rotation angle measurement reference plate fixed on the large gear, the rotation angle value θ of the large gear can be measured. Through the meshing line displacement measurement mechanism, the displacement value L in the meshing line direction of the large gear can be obtained, and the tooth profile deviation value of the large gear can be solved by Equation (1); where, ΔF αi Tooth profile deviation value, α is the pressure angle of the large gear to be measured, is the included angle value between the two linear measurement guide rails, i is the number of measurement records, i = 1, 2, 3..., n; the total tooth profile deviation of the finally measured large gear can be obtained by Equation (2), where, F α is the total tooth profile deviation, max(ΔF αi ) is the maximum tooth profile deviation value, min(ΔF αi ) is the minimum tooth profile deviation value; F α = max(ΔF αi ) - min(ΔF αi ) (2).

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