Method for automatically measuring surface appearance and pitch deviation of cylindrical gear by using roughness contourgraph

Abstract

The invention discloses a method for automatically measuring the surface appearance and pitch deviation of a cylindrical gear by using a roughness contourgraph. The method comprises the following steps of: mounting a measured gear on a servo rotary table, and rotating a rotary body to adjust the gear to an optimal measurement position; adjusting the measuring head of the roughness contourgraph to a No.1 tooth positioning point Ff of the measured gear; controlling the roughness contourgraph and the rotary table to scan and measure all gear tooth profiles in a linkage manner; extracting tooth profile part curves of all the gear teeth from the scanning curve, performing least square fitting on the curves and a theoretical tooth profile, mapping the curves and the theoretical tooth profile to a gear coordinate system, and calculating to obtain multi-scale surface topography of each gear tooth; and calculating the pitch deviation of all the gear teeth according to the rotation angle data recorded by the rotary table in the gear measurement process and the least square fitting result. Automatic linkage of a contact type roughness contourgraph and a high-precision gear indexing table is used for completing collection of tooth profile shapes and tooth indexing angles theta i of all gear teeth at a time, and multi-scale surface shape deviations and tooth pitch deviations of all the gear teeth are obtained through data processing and calculation.

Description

Technical Field

[0001] The present invention belongs to the field of precision measurement, and is specifically a method for automatically measuring the surface morphology and pitch deviation of cylindrical gears using a roughness profiler. The present invention installs a high-precision servo gear turntable on a stylus-type roughness profiler, and realizes automatic measurement of multi-scale surface morphology and pitch deviation of all gear teeth of the cylindrical gear through linkage measurement of the roughness profiler and the turntable. Background Art

[0002] Gears are key mechanical parts that rely on the mutual meshing of working tooth surfaces to transmit motion and power. Their processing quality and service performance have an important impact on the service performance and reliability of mechanical equipment. The surface morphology of gears has multi-scale characteristics, usually including roughness, waviness and shape deviation. Surface morphologies of different scales often have different effects in the process of gear transmission. The roughness of the tooth surface has an important influence on the lubrication performance, load-bearing capacity and fatigue resistance of the gear. The waviness of the tooth surface often easily causes gearbox noise and causes the "ghost step" phenomenon. Shape deviation will bring greater transmission errors and even meshing shocks. Pitch deviation affects the transmission smoothness of the gear, reduces transmission efficiency, and increases the risk of gear damage. Accurately measuring and calculating tooth surface morphology deviation and pitch deviation are of great significance to improving the service performance of gears. As a reference for testing and evaluating gear processing quality, the national standard GB10095.1-2022 defines gear accuracy grades from the highest grade 1 to the lowest grade 11, and the international standard ISO1328-1:2013 defines gear accuracy grades from the highest grade 1 to the lowest grade 12. α and pitch deviation f pt 、F p It is an important testing item and has important guiding significance for evaluating and controlling gear processing quality.

[0003] At present, the commonly used means for detecting tooth profile and pitch deviation are gear measurement centers and three-dimensional coordinate measuring machines, but these measurement methods are difficult to obtain multi-scale surface morphology of tooth profile at the same time. Since the pitch deviation in contact measurement is often measured by sampling in the middle of the full tooth height, the measurement of pitch deviation is also prone to introduce additional measurement errors due to poor tooth surface quality. Therefore, it is difficult for traditional measurement methods to obtain richer gear morphology deviation information while ensuring sufficient measurement accuracy. The patent (application number: 201910804104.0) proposes a gear pitch deviation measurement method based on a stylus roughness profiler and a high-precision gear rotary fixture, but this method cannot realize automatic measurement of all gear teeth, and has high requirements on the rotary positioning accuracy of the fixture and the fitting accuracy of the measurement data. The obtained pitch deviation is calculated based on the average tooth profile line, which is inconsistent with the pitch deviation measurement and evaluation method of the current gear accuracy evaluation standard.

[0004] The surface roughness profiler is a contact-type surface profile measuring instrument that can accurately measure the multi-scale geometric profile of the workpiece, including shape profile, surface waviness, surface roughness, etc. Gears are rotating mechanical parts. When they are installed on a high-precision servo rotary indexing table, the roughness profiler can be used to achieve automatic linkage measurement of the entire gear, and the one-time automatic acquisition of the surface profile of all gear teeth and the indexing angle between teeth can be achieved. The gear tooth profile deviation and pitch deviation can also be calculated through data processing. Summary of the invention

[0005] The purpose of the present invention is to provide a method for measuring the surface morphology and pitch deviation of a gear by automatically linking a roughness profiler and a turntable. The present invention measures the surface morphology of the entire tooth profile of the entire gear at one time through the automatic linkage of a contact roughness profiler and a servo turntable, and the surface morphology and pitch deviation of each tooth profile of the measured gear can be obtained through data processing.

[0006] The invention provides a gear automatic measuring method, which measures the surface morphology and pitch deviation of all gear teeth of the gear at one time through the automatic linkage of a roughness profiler and a rotary table.

[0007] The present invention provides a data processing method, which fits the measured tooth profile to the corresponding position of the gear to obtain the tooth profile deviation, compares the measured pitch angle with the theoretical pitch angle to obtain the pitch deviation angle, and performs a more reasonable pitch deviation calculation in combination with the tooth profile morphology deviation.

[0008] In order to realize automatic linkage measurement between a roughness profiler and a turntable, the technical solution adopted by the present invention is a method for automatically measuring the surface morphology and pitch deviation of a cylindrical gear using a roughness profiler. The method installs a high-precision servo rotary turntable on a stylus-type roughness profiler; the roughness profiler includes a contact probe system, a drive box, a column and a base; the drive box is installed on the column and can move along the vertical z-axis, the contact probe system is installed on the drive box, the probe system can move along the horizontal x-axis, and the column is installed on the base; the probe of the roughness profiler can move freely within the measurement range of the xOz plane through an automatic program. The high-precision servo rotary table includes a rotary indexing table, a longitudinal track of the indexing table, a circular grating angle sensor and a servo motor; the rotary indexing table is installed on the base of the roughness profiler through the longitudinal track, so that the indexing table moves along the longitudinal y-axis to adjust the measuring position in the tooth width direction; the gear to be measured is installed on the chuck of the rotary indexing table, the servo motor drives the gear to be measured to rotate in the xOz plane, and the circular grating angle sensor records the rotation angle θ of each index of the gear to be measured i .

[0009] The stylus roughness profiler and the servo rotary table are automatically linked to complete the measurement of all tooth profiles and pitches of the gear under test at one time, and the tooth profile shape deviation and pitch deviation are obtained through data processing. The method includes the following implementation steps: Step 1, install the gear under test and adjust the tooth surface to the optimal measurement position; Step 2, adjust the roughness profiler probe to the positioning point F of the No. 1 tooth of the gear under test f , and mark the spatial coordinates of the positioning point; Step 3, control the roughness profiler and the gear indexing table to automatically scan and measure all gear tooth profiles and pitch angles; Step 4, perform least squares fitting on the measured curve and the theoretical tooth profile to obtain the multi-scale surface morphology P zi ; Step 5, calculate the pitch deviation f between each tooth pti . BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the three-dimensional measurement structure of the present invention.

[0011] Figure 2 It is a front view of the measurement structure of the present invention.

[0012] Figure 3 It is a schematic diagram of adjusting the optimal measuring position of the gear to be measured according to the present invention.

[0013] Figure 4 It is a schematic diagram of the automatic linkage measurement process of the tooth profile and the pitch angle of the present invention.

[0014] Figure 5 It is a schematic diagram of the tooth profile deviation and pitch deviation of the gear to be measured according to the present invention.

[0015] Figure 6 This is a gear measurement flow chart of the present invention. DETAILED DESCRIPTION

[0016] The present invention provides a method for automatically linking the measurement of gear surface topography and pitch deviation using a roughness profiler and a high-precision servo rotary table. The three-dimensional structure of the measuring system is as follows: Figure 1As shown, the main structure of the roughness profiler is composed of a probe system (including a measuring stylus 8 and a sensor system 9), a drive box 10, a column 11, a granite base 4, a base transverse guide 5 and a longitudinal guide 7. The automatic movement of the roughness profiler probe in the xOz plane is composed of the z-direction movement of the drive box on the column and the x-direction movement of the drive box driving the probe system. The measuring stylus scans and slides across the target tooth profile to record the contour fluctuation changes of the tooth surface along the z-direction. The main structure of the high-precision servo rotary turntable is composed of a circular grating angle sensor 1, a precision rotary turntable 2 and a servo motor 3. The middle part of the base of the precision rotary turntable is processed with a longitudinal track 12 that matches the guide rail of the roughness profiler base. The high-precision servo rotary turntable can slide freely along the y-axis direction on the longitudinal guide rail 7 of the roughness profiler to adjust the measurement position in the gear tooth width direction; the servo motor 3 can drive the turntable to rotate and adjust the position of the tooth surface to be measured. The circular grating angle sensor records the pitch angle θ between each measuring tooth in turn. In the automatic linkage measurement process, the rotation direction of the gear is along the y-axis direction. Figure 2 Counterclockwise from front view shown.

[0017] The present invention provides a method for adjusting the optimal measuring position of the tooth surface to be measured. The first step is to install the gear to be measured on the three-jaw chuck of the turntable 2, and push the gear horizontally to fit tightly against the end face of the chuck. The second step is to adjust the position of the turntable in the y-axis direction along the longitudinal track 7 of the base so that the roughness profiler probe is aligned with the middle of the tooth width; the third step is to drive the motor to rotate the turntable to adjust the position of tooth No. 1, such as Figure 3 As shown, the root of tooth No. 1 is formed into point F f To the tooth top forming point F a The connection F f F a Angle with the horizontal x-axis Equal to the tooth root forming point F f To the highest point F of the tooth profile h The connection F f F h Angle with the horizontal x-axis The characteristic mark of the tooth surface to be measured being adjusted to the best measuring position is that the roughness profiler is adjusted from F f Scan to F a The absolute values ​​of the maximum value max(z) and the minimum value min(z) in the measured tooth profile data z(x) are equal; where:

[0018]

[0019] d Ff =d b / cosα F

[0020] d Fa =d a -2hk

[0021] α F is the pressure angle of the tooth root forming point, α n is the gear normal pressure angle, h a * is the tooth top height coefficient, x is the gear displacement coefficient, Z is the number of gear teeth, d Ff is the tooth root forming circle diameter, d b is the base diameter of the gear, d Fa is the diameter of the tooth tip forming circle, d a is the diameter of the tooth tip circle, h k is the height of the tooth top chamfer; the highest point of the tooth profile is F h By F f F a The parallel line connecting the tooth profile is determined, and the tangent point is approximately the highest point of the tooth profile F. h .

[0022] The present invention provides a method for marking the positioning points of a gear to be measured. After the optimal measuring position of the first tooth of the gear is adjusted, the contact probe of the roughness profiler is moved to the tooth root forming point F of the first tooth. f The roughness profiler is in contact with the surface of the surface and the probe of the roughness profiler is kept in a horizontal position. The roughness profiler marks the spatial position coordinate F of the point in the instrument coordinate system. f1 (x0, y0, z0) is the positioning point for automatic linkage measurement of gears. The positioning point is also the starting point for all tooth profile measurements.

[0023] The present invention provides a method for automatically linking the gear profile to measure. After the gear to be measured is installed and adjusted and the positioning points are marked, the following steps are performed: Figure 4 The automatic linkage measurement process of the gear shown in the figure is as follows: the first step is to make the roughness profiler drive box drag the probe system so that the probe moves from position F shown in ① to f1 Start scanning the entire tooth profile along the x-axis and record the data, passing through F shown in position ② a After the probe of the profiler slides down from the top of the tooth and continues to move 1 to 2 mm of safety travel to position ③, the measurement of the profile of tooth No. 1 is completed. The second step is that when the probe of the profiler slides down from the top of the tooth, the servo motor is triggered to control the gear indexing table to rotate slowly, so that tooth No. 2 slowly approaches the best measurement position; the third step is that when the middle of the gap between tooth No. 1 and tooth No. 2 rotates to the positioning point F f1 When the roughness profiler moves the probe from position ④ along the x-axis direction and automatically returns to the marked positioning point F after completing the safety stroke. f1The fourth step is to wait for the servo motor to control the gear indexing table to slowly rotate until it contacts the probe at the return positioning point, and continue to rotate until the probe needle returns to the horizontal position (parallel to the x-axis) and then stop rotating. At this time, the root forming point F of tooth No. 2 is f2 With the anchor point F f1 The two gears overlap in space, and tooth No. 2 is in the best measurement position; the circular grating angle sensor records the rotation angle θ1 of the gear indexing table, completing the measurement of tooth No. 1. In the fourth step, the roughness profiler automatically repeats step 3 and automatically links to complete the tooth profile and rotation angle θ of all gear teeth. i Measure and record the data.

[0024] The present invention provides a method for processing measurement data. In the first step, the measurement data of the roughness profiler is read, and the measurement data of all gear tooth profiles are plotted. The measurement data of each gear tooth is obtained from the tooth root F f From the point where the tooth tip starts to slide off, it includes the involute tooth profile and part of the tooth tip profile. After the measurement curve is low-pass filtered to remove the interference of high-frequency roughness components, the inflection point F of the tooth tip in the measurement curve is determined by local curvature calculation. a The involute tooth profile is found and the involute measured tooth profile of each gear tooth is cut out in turn. The second step is to fit the theoretical tooth profile and the measured tooth profile using the least squares principle, remove the nominal shape of the theoretical tooth profile, and obtain the multi-scale surface morphology P of each gear tooth. zi The diagram for measuring the surface topography deviation and pitch error of the tooth profile is as follows: Figure 5 As shown, during a single linkage measurement, there is an angular deviation Δθ between the actual rotational position 14 of the gear and the theoretical rotational position 15 i Since the tooth profile 14 obtained by actual measurement has tooth profile deviation, the measurement positioning point F f The angle deviation measured at the gear pitch circle is not consistent with the angle deviation measured at the gear pitch circle 13. The pitch deviation measurement result needs to be corrected according to the tooth profile deviation. The third step is to read the pitch angle data θ of the circular grating angle sensor. i , calculate the measured pitch deviation angle Δθ between each gear tooth it =θ i -2π / Z. The fourth step is to correct the error of the tooth profile deviation in the measurement to the pitch deviation calculation. The actual pitch deviation angle calculation formula is as follows:

[0025]

[0026] where z Ff(i+1) represents the tooth profile deviation value of the i+1th tooth at point Ff, z Ff(i) Represents the i-th tooth in F f The tooth profile deviation value at point r Ffis the radius of the tooth root forming circle. Note that Z+tooth No. 1 in the formula is tooth No. 1.

[0027] Step 5: Calculate the pitch deviation:

[0028] f pti =Δθ i *r d (i∈[1,Z])

[0029] where f pt is the single pitch deviation between each gear tooth, r d is the gear pitch circle radius.

[0030] It should be noted that according to the ISO1328-1:2013 tooth surface tolerance grade assessment standard, the single pitch deviation is obtained by contact sampling of two adjacent tooth surfaces in the middle of the tooth width. Therefore, the measured pitch deviation includes the tooth profile deviation of the measuring point. Therefore, the calculation of the single pitch deviation unified with the standard should be:

[0031] f pti =Δθ i *r d +z d(i) -z d(i+1) ,(i∈[1,Z])

[0032] where z d(i) represents the tooth profile deviation value of the i-th tooth on the gear pitch circle, z d(i+1) Represents the tooth profile deviation value of the i+1th tooth on the gear pitch circle.

[0033] The flow chart of automatic measurement of cylindrical gear surface topography and pitch deviation using roughness profiler is shown in Figure 6.

Claims

1. A method for automatically measuring the surface topography and pitch deviation of cylindrical gears using a roughness profiler, wherein a high-precision servo rotary table is installed on a stylus-type roughness profiler; the roughness profiler comprises a contact probe stylus (8), a probe system sensor (9), a drive box (10), a column (11) and a base (4), wherein a transverse guide rail (5) and a longitudinal guide rail (7) are machined on the base; the drive box is installed on the column and moves along the vertical z-axis, and a contact probe system is installed on the drive box, and the probe system moves along the transverse The rotary table is provided with a servo motor and a rotary table. The rotary table is provided with a servo motor and a rotary table. The servo motor is provided with a servo motor and a rotary table. The servo motor is provided with a servo motor and a rotary table. The servo motor is provided with a servo motor and a rotary table. The servo motor is provided with a servo motor and a rotary table. The servo table ... i ; Features: The stylus roughness profiler and the servo rotary table are used to measure all the tooth profiles and pitches of the gear under test in a step-by-step manner, and the tooth profile morphology and pitch deviation are obtained through data processing; the method includes the following implementation steps: Step 1: Install the gear to be measured and adjust the tooth surface to the best measuring position; Step 2: Adjust the roughness profiler probe to the positioning point F of tooth No. 1 of the gear being measured f , and mark the spatial coordinates of the positioning point; Step 3: Control the roughness profiler and the gear indexing table to automatically scan and measure the tooth profiles of all gear teeth; Step 4: Perform least squares fitting between the measured curve and the theoretical tooth profile to obtain the multi-scale surface morphology P zi ; Step 5: Calculate the pitch deviation f between each tooth pti .

2. The method for automatically measuring the surface topography and pitch deviation of cylindrical gears using a roughness profiler according to claim 1, characterized in that: The installation and adjustment method of the gear to be measured is implemented as follows: the first step is to install the gear to be measured on the chuck of the turntable and clamp it; the second step is to adjust the position of the turntable in the y-axis direction along the longitudinal track so that the roughness profiler probe is aligned with the middle of the tooth width; the third step is to drive the motor to rotate the turntable to adjust the position of tooth No. 1 so that the root forming point F of tooth No. 1 is f To the tooth top forming point F a The connection F f F a Angle with the horizontal x-axis Equal to the tooth root forming point F f To the highest point F of the tooth profile h The connection F f F h Angle with the horizontal x-axis The characteristic mark of the tooth surface to be measured being adjusted to the best measuring position is that the roughness profiler is adjusted from F f Scan to F a The absolute values ​​of the maximum value max(z) and the minimum value min(z) in the measured tooth profile data z(x) are equal; where: d Ff =d b / cosα F <h2 style=";text-align:left;direction:ltr">d<h2 style=";text-align:left;direction:ltr"> Fa <h2 style=";text-align:left;direction:ltr"> =d<h2 style=";text-align:left;direction:ltr"> a <h2 style=";text-align:left;direction:ltr"> -2 hours<h2 style=";text-align:left;direction:ltr"> k α F is the pressure angle of the tooth root forming point, α n is the gear normal pressure angle, h a * is the tooth top height coefficient, x is the gear displacement coefficient, Z is the number of gear teeth, d Ff is the tooth root forming circle diameter, d b is the base diameter of the gear, d Fa is the diameter of the tooth tip forming circle, d a is the diameter of the tooth tip circle, h k is the height of the tooth top chamfer; the highest point of the tooth profile is F h By F f F a The parallel line connecting the tooth profile is determined, and the tangent point is approximately the highest point of the tooth profile F. h .

3. The method for automatically measuring the surface topography and pitch deviation of cylindrical gears using a roughness profiler according to claim 1, characterized in that: The steps for adjusting the roughness profiler probe mark positioning point are as follows: after the optimal measurement position of the gear is adjusted, move the contact probe of the roughness profiler to the root forming point F of tooth No.

1. f The roughness profiler is in contact with the surface of the surface and the probe of the roughness profiler is kept in a horizontal position. The roughness profiler marks the spatial position coordinate F of the point in the instrument coordinate system. f1 (x0,y0,z0) is used as the positioning point for contour measurement.

4. The method for automatically measuring the surface topography and pitch deviation of cylindrical gears using a roughness profiler according to claim 1, characterized in that: The method and steps of controlling the roughness profiler and the gear indexing table to automatically link and scan and measure the tooth profiles of all gear teeth are as follows: after the gear to be measured is installed and adjusted and the positioning points are marked, the roughness profiler drive box is used to drag the probe system so that the probe moves from F f1 Start scanning the entire tooth profile along the x-axis and record the data. a After the profilometer probe slides down from the tooth top and continues to travel 1 to 2 mm of safety travel, the measurement of tooth profile No. 1 is completed; after the profilometer probe slides down from the tooth top, the servo motor is triggered to control the gear indexing table to rotate slowly, so that tooth No. 2 approaches the best measurement position. At the same time, the roughness profilometer mobile probe that has completed the safety travel automatically returns to the marked positioning point F f1 The servo motor controls the gear indexing table to rotate slowly until it contacts the probe at the return positioning point, and continues to rotate until the probe needle returns to the horizontal position, that is, parallel to the x-axis, and then stops rotating. At this time, the root forming point F of tooth No. 2 f2 With the anchor point F f1 The gears overlap in space, and tooth No. 2 is in the best measurement position. The circular grating angle sensor records the rotation angle θ1 of the gear indexing table, and the measurement of tooth No. 1 is completed. Then the roughness profiler automatically repeats step 3 and automatically links in sequence to complete the tooth profile and rotation angle θ of all gear teeth. i Measure and record the data.

5. The method for automatically measuring the surface topography and pitch deviation of cylindrical gears using a roughness profiler according to claim 1, characterized in that: The steps of the method for obtaining the measured tooth profile morphology are as follows: the first step is to read the measurement curve of the roughness profile meter, and determine the involute tooth profile in the measurement curve by curvature calculation, and cut out the involute measurement tooth profile of each gear tooth in turn; the second step is to fit the theoretical tooth profile and the measured tooth profile using the least squares principle, remove the nominal shape of the theoretical tooth profile, and obtain the multi-scale surface morphology deviation curve P of each gear tooth. zi .

6. The method for automatically measuring the surface topography and pitch deviation of cylindrical gears using a roughness profiler according to claim 1, characterized in that: The calculation method of the pitch deviation is as follows: The first step is to read the pitch angle data θ of the circular grating angle sensor. i , calculate the measured pitch deviation angle Δθ between each gear tooth it =θ i -2π / Z; The second step is to eliminate the error of the tooth profile deviation in the measurement on the calculation of the pitch deviation. The actual pitch deviation angle calculation formula is as follows: where z Ff(i+1) Represents the i+1th tooth in F f Tooth profile deviation value at point z Ff(i) Represents the i-th tooth in F f The tooth profile deviation value at point r Ff is the tooth root forming circle radius. Note that the Z+1 tooth in the formula is the 1st tooth; The third step is to calculate the pitch deviation: f pti =Δθ i *r d ,(i∈[1,Z]) where f pti is the single pitch deviation of each gear tooth, r d is the gear pitch circle radius; The calculation of the single pitch deviation according to the standard should be: f pti =Δθ i *r d +from d(i) -With d(i+1) ,(i∈[1,Z]) where z d(i) represents the tooth profile deviation value of the i-th tooth on the gear pitch circle, z d(i+1) Represents the tooth profile deviation value of the i+1th tooth on the gear pitch circle.

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