A detection method for the crankshaft of an ultra-high precision RV reducer

Abstract

The present invention relates to a detection method for an ultra-high precision RV reducer crankshaft, comprising: a contact displacement sensor M1 stops at a preset measurement position, the crankshaft rotates, M1 measures displacement data M1-n, a linear displacement sensor M2 measures the position of M1 in the vertical direction, and an angle sensor M3 measures angle data M3-n; based on a calibration distance, real data of each measurement position is obtained; based on the real data, angle data and the measurement data of M2, the geometric parameters of the crankshaft are calculated. Compared with the prior art, the present invention uses a preset measurement position to quickly collect data from various locations of the crankshaft through an RV reducer crankshaft detection device, and can calculate the radius measurement values ​​of various locations of the crankshaft with high precision in combination with the calibration distance. The center coordinates and radius of each part of the crankshaft are determined by coordinate transformation and least squares method fitting circle, and then the geometric parameters of the crankshaft are calculated, which is faster and more adaptable, and can achieve micron-level detection accuracy.

Description

Technical Field

[0001] The invention relates to a crankshaft detection method, in particular to a detection method for an ultra-high precision RV reducer crankshaft. Background Art

[0002] RV reducer is a transmission device with a series of advantages such as small size, light weight, wide transmission ratio range, long life, high precision, high efficiency, smooth transmission, strong impact resistance, large torque, low vibration, etc. It is widely used in industrial robots and machine tools and is an essential component of industrial automation. With the rapid development of the manufacturing industry, as a key component of industrial robots, the market demand for RV reducers has increased, and the crankshaft is a key part of the RV reducer. Therefore, the design and production of various RV reducers require the corresponding crankshaft detection equipment.

[0003] The accuracy of the crankshaft affects the overall performance of the RV reducer, thereby affecting the overall accuracy of the industrial robot. Therefore, the detection of the crankshaft is crucial in the production of the RV reducer. It is an important link in quality assurance and seriously affects the assembly accuracy. For the detection of the crankshaft, including the detection of coaxiality, cylindricity and other parameters, in the prior art, Chinese patent CN202111596696.5 discloses a special measuring device for the crankshaft of an ultra-high precision RV reducer, and constructs a device for detecting geometric parameters through a contact measuring instrument during the rotation process, which is used to detect various data of the produced crankshaft, thereby ensuring the quality and accuracy of the crankshaft. However, the above patent does not disclose a systematic measurement method, and it is difficult to achieve the detection of ultra-high precision RV reducer crankshafts. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting an ultra-high precision RV reducer crankshaft in order to overcome the defects of the above-mentioned prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] An ultra-high precision RV reducer crankshaft detection method is implemented based on an RV reducer crankshaft detection device, wherein the RV reducer crankshaft detection device includes a control system, a drive system, a contact displacement sensor M1, a linear displacement sensor M2 and an angle sensor M3;

[0007] Specifically, the detection method includes the following steps:

[0008] Step 1, the driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at a preset measuring position, and the probe of the contact displacement sensor M1 extends out and contacts the crank shaft;

[0009] Step 2, the crankshaft is driven by the driving system to rotate axially. During the rotation of the crankshaft, the contact displacement sensor M1 measures the displacement data M1-n of the crankshaft relative to the measurement origin of the contact displacement sensor M1. The linear displacement sensor M2 is used to measure the position of the contact displacement sensor M1 in the vertical direction. The angle sensor M3 measures the angle data M3-n of the crankshaft, where n is an integer used to indicate different measurement positions.

[0010] Step 3, preset N+1 measurement positions, N>0, repeat Step 1 to Step 2 until the displacement data and angle data of each measurement position are obtained: {M1-n, n=0, ..., N}, {M3-n, n=0, ..., N};

[0011] Step 4. Obtain the pre-stored calibration distances of each measurement position (H0, ..., H N ), the calibration distance is the distance between the measurement origin of the contact displacement sensor M1 and the rotation center of the crankshaft, and the displacement data is subtracted from the calibration distance of each measurement position to obtain the real data {Pn, n=0, ..., N} of each measurement position;

[0012] Step 5. The center coordinates and radius of each measuring position are calculated based on the real data, angle data and the measurement data of the linear displacement sensor M2. The geometric parameters of the crankshaft are calculated according to the correspondence between the center coordinates and radius of each measuring position and the geometric parameters of the crankshaft.

[0013] Preferably, step 5 is specifically as follows:

[0014] Step 51, filter the real data to remove the inherent frequency noise of the equipment;

[0015] Step 52, select a measurement position, match the real data with the angle data one by one, obtain multiple points of the measurement position, perform coordinate conversion on all points, convert the polar coordinate system to the rectangular coordinate system, combine the measurement data of the linear displacement sensor M2, obtain the coordinates of all points of the measurement position in the rectangular coordinate system, repeat this step until the coordinates of all points of all measurement positions in the rectangular coordinate system are obtained;

[0016] Step 53, select a measurement position, perform least squares fitting of a circle on all points of the measurement position in the rectangular coordinate system, obtain the center coordinates and radius of the measurement position, and repeat this step until the center coordinates and radius of all measurement positions are obtained;

[0017] Step 54: Calculate the geometric parameters of the crankshaft based on the corresponding relationship between the center coordinates and radius of each measuring position and the geometric parameters of the crankshaft.

[0018] Preferably, step Step51 is specifically as follows: select a measurement position, perform FFT fast Fourier transform on the real data of the measurement position, convert it into frequency domain data, remove the high-frequency components in the frequency domain, and then perform iFFT inverse transform to convert it back to time domain data, complete the filtering calculation of the measurement position, and repeat this step until the filtering calculation of each measurement position is completed.

[0019] Preferably, the crankshaft includes a spline K, a spline side cylinder C1, a spline side eccentric shaft C2, a non-spline side eccentric shaft C3 and a non-spline side cylinder C4 from bottom to top. The spline K, the spline side cylinder C1 and the non-spline side cylinder C4 are coaxial, and their axes are the rotation center of the crankshaft. The spline part is pressed by a pair of ejector pins G, and the driving system drives the crankshaft to rotate through the ejector pins. There are 8 preset measuring positions, denoted as Z0~Z7, which are arranged in pairs on the spline side cylinder C1, the spline side eccentric shaft C2, the non-spline side eccentric shaft C3 and the non-spline side cylinder C4.

[0020] Preferably, the center coordinates of each measurement position are obtained ( xyz -0~O xyz -7) and radius (R0~R7):

[0021] The center coordinates of the spline side cylinder C1 are (O xyz -0+O xyz -1) / 2, the radius is (R0+R1) / 2;

[0022] The center coordinates of the eccentric shaft C2 on the spline side are ( xyz -2+O xyz -3) / 2, the radius is (R2+R3) / 2;

[0023] The center coordinates of the eccentric shaft C3 on the non-spline side are ( xyz -4+O xyz -5) / 2, the radius is (R4+R5) / 2;

[0024] The center coordinates of the non-spline side cylinder C4 are (O xyz -6+O xyz -7) / 2, the radius is (R6+R7) / 2;

[0025] The eccentricity of the crankshaft is the distance between the spline side eccentric shaft C2 and the non-spline side eccentric shaft C3 and the central axis, and the central axis is the line connecting the centers of the spline side cylinder C1 and the non-spline side cylinder C4;

[0026] The coaxiality of the crankshaft is O xyz -0, O xyz -1, O xyz -6, O xyz -7 The maximum distance from the central axis multiplied by 2;

[0027] The cylindricality of the crankshaft is equal to (O xyz -0~O xyz -7) The maximum value minus the minimum value of the distance to the center axis.

[0028] Preferably, the method for determining the calibration distance of each measurement position is:

[0029] Take a part whose geometric parameters have been measured. The driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at the preset measurement position. The driving system drives the part to rotate axially. During the rotation of the part, the contact displacement sensor M1 measures the displacement data of the part relative to the measurement origin of the contact displacement sensor M1. The displacement data is added to the radius of the part at the measurement position and the average is taken to obtain the calibration distance at each measurement position.

[0030] Preferably, the method for determining the calibration distance of each measurement position is:

[0031] Take a part whose geometric parameters have been measured. The driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at a part of the measuring position. The driving system drives the part to rotate axially. During the rotation of the part, the contact displacement sensor M1 measures the displacement data of the part relative to the measuring origin of the contact displacement sensor M1. The displacement data is added to the radius of the part at the measuring position and the average is taken to obtain the calibration distance at a part of the measuring position. The calibration distance at the remaining measurement position is obtained by fitting using the least squares method.

[0032] Preferably, the part is a crankshaft or shaft column part.

[0033] Preferably, in the RV reducer crankshaft detection equipment, the driving system includes a driving motor S1, a driving motor S2 and a driving cylinder, the driving motor S1 drives the contact displacement sensor M1 to move in the vertical direction, the driving motor S2 drives the crankshaft to rotate axially, and the driving cylinder drives the contact displacement sensor M1 to extend and retract in the horizontal direction, and the driving motor S1, the driving motor S2 and the driving cylinder are controlled by a control system.

[0034] Preferably, the RV reducer crankshaft detection equipment also includes a data acquisition system, and the contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3 are connected to the control system through the data acquisition system, and the measurement values ​​of the contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3 are synchronously transmitted to the control system.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) By presetting the measurement position, the RV reducer crankshaft detection equipment can quickly collect data from various parts of the crankshaft. Combined with the calibrated distance, the radius measurement value of each part of the crankshaft can be calculated with high precision. The center coordinates and radius of each part of the crankshaft are determined by coordinate transformation and least squares method fitting circle, and then the geometric parameters of the crankshaft are calculated. It is faster and more adaptable, and can achieve micron-level detection accuracy, realizing ultra-high precision RV reducer crankshaft detection.

[0037] (2) Considering that the distance between the measurement origin and the crankshaft rotation center will change slightly after the contact displacement sensor M1 moves in the vertical direction, the measurement position is preset and the calibration distance is measured to eliminate the error. As long as the rotation center is not readjusted, the crankshaft parts can be continuously inspected.

[0038] (3) The displacement data and angle data are combined and transformed into a Cartesian coordinate system through coordinate transformation. The center coordinates and radius of each position are determined by fitting the circle using the least squares method. The geometric parameters of the crankshaft are calculated in the coordinate system with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the detection of the crank shaft;

[0040] Figure 2 is a schematic diagram of the measurement location;

[0041] Figure 3 This is a structural diagram of the RV reducer crankshaft detection equipment;

[0042] Figure 4 is a flow chart of a crankshaft detection method;

[0043] Figure 5 Schematic diagram of the data model for calibrating distance, displacement data and real data;

[0044] Figure 6 This is a schematic diagram of the calibration distance;

[0045] Figure numerals: 1. crank shaft, 2. control system, 3. data acquisition system. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0047] In the drawings, components with the same structure are indicated by the same numerical labels, and components with similar structures or functions are indicated by similar numerical labels. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, some parts in the drawings are appropriately exaggerated.

[0048] Embodiment 1:

[0049] The schematic diagram of the crankshaft 1 for data measurement is as follows Figure 1 The crankshaft 1 includes from bottom to top a spline K, a spline side cylinder C1, a spline side eccentric shaft C2, a non-spline side eccentric shaft C3 and a non-spline side cylinder C4. During the inspection, the upper and lower ends of the crankshaft 1 are clamped and fixed by a top (not shown in the figure) to limit its axial freedom.

[0050] The spline K, the spline side cylinder C1 and the non-spline side cylinder C4 are coaxial, and their axis is the rotation center of the crankshaft 1. In the spline part, there is a pair of ejector pins G pressing against the tooth root of the spline K. The ejector pins G can rotate around the axial direction of the crankshaft 1 under the drive of the external driving mechanism. Therefore, when the upper and lower centers press the crankshaft 1, the crankshaft 1 will rotate axially under the drive of the ejector pins G, overcoming the friction resistance of the upper and lower centers.

[0051] The RV reducer crankshaft detection device includes a control system 2, a drive system, a contact displacement sensor M1, a linear displacement sensor M2 and an angle sensor M3, as shown in Chinese patent CN202111596696.5. Figure 1 , Figure 2 and Figure 3 As shown, the control system 2 is connected to the drive system, the contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3. The drive system includes a drive motor S1, a drive motor S2 and a drive cylinder A. The drive motor S1 drives the contact displacement sensor M1 to move in the vertical direction, the drive motor S2 drives the crankshaft 1 to rotate around the axial direction, and the drive cylinder A drives the contact displacement sensor M1 to extend and retract in the horizontal direction. The drive motor S1, the drive motor S2 and the drive cylinder A are controlled by the control system 2. The RV reducer crankshaft detection equipment also includes a data acquisition system 3, which is used to perform operations such as signal amplification and AD conversion. The contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3 are connected to the control system 2 through the data acquisition system 3, and the measurement values ​​of the contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3 are synchronously transmitted to the control system 2.

[0052] During detection, based on the real-time measurement feedback of the linear displacement sensor M2, the contact displacement sensor M1 moves to a measurement position at a specific height under the drive of the drive motor S1, and the probe of the contact displacement sensor M1 moves to the contact position with the crank shaft 1 under the drive of the drive cylinder A. During the rotation of the ejector pin G, the probe of the contact displacement sensor M1 always keeps in contact with the crank shaft 1. The contact displacement sensor M1 and the angle sensor M3 collect data until the crank shaft 1 rotates a complete circle.

[0053] A method for detecting the crankshaft of an ultra-high precision RV reducer, such as Figure 4 As shown, the following steps are included:

[0054] Step 1, the driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at a preset measuring position;

[0055] Step 2, the probe of the contact displacement sensor M1 is extended and contacts the crank shaft 1, and the driving system drives the crank shaft 1 to rotate around the axial direction. During the rotation of the crank shaft 1, the contact displacement sensor M1 measures the displacement data M1-n of the crank shaft 1 relative to the measurement origin of the contact displacement sensor M1, the linear displacement sensor M2 is used to measure the position of the contact displacement sensor M1 in the vertical direction, and the angle sensor M3 measures the angle data M3-n of the crank shaft 1, where n is an integer used to indicate different measurement positions;

[0056] Step 3, preset N+1 measurement positions, N>0, repeat steps Step 1 to Step 2, until the displacement data and angle data of each measurement position are obtained: {M1-n, n=0, ..., N}, {M3-n, n=0, ..., N}. It can be understood that in order to ensure the measurement accuracy, the data of each measurement position should be collected from top to bottom or from bottom to top. Taking n=0 as an example, M1-0 and M3-0 are data sets, containing multiple data (generally hundreds of data). M1-0 records the distance between the measurement origin of the contact displacement sensor M1 and the crankshaft 1 collected at equal time intervals during the rotation of the crankshaft 1. M3-0 records the rotation angle value of the crankshaft 1 measured by the angle sensor M3 collected at equal time intervals during the rotation of the crankshaft 1.

[0057] Step 4. Obtain the pre-stored calibration distances of each measurement position (H0, ..., H N ), the calibration distance is the distance between the measurement origin of the contact displacement sensor M1 and the rotation center of the crankshaft 1, and the displacement data is subtracted from the calibration distance of each measurement position to obtain the real data {Pn, n=0, ..., N} of each measurement position;

[0058] There are many methods for measuring the calibration distance. Select the crankshaft 1 or other shaft column parts. This embodiment provides the following two implementation methods:

[0059] ① The method for determining the calibration distance of each measurement position is:

[0060] Take a part whose geometric parameters have been measured. The driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at the preset measurement position. The driving system drives the part to rotate axially. During the rotation of the part, the contact displacement sensor M1 measures the displacement data of the part relative to the measurement origin of the contact displacement sensor M1. The displacement data is added to the radius of the part at the measurement position and the average is taken to obtain the calibration distance at each measurement position.

[0061] ②The method for determining the calibration distance of each measurement position is:

[0062] Take a part whose geometric parameters have been measured. The driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at a part of the measuring position. The driving system drives the part to rotate axially. During the rotation of the part, the contact displacement sensor M1 measures the displacement data of the part relative to the measuring origin of the contact displacement sensor M1. The displacement data is added to the radius of the part at the measuring position and the average is taken to obtain the calibration distance at a part of the measuring position. The calibration distance at the remaining measurement position is obtained by fitting using the least squares method.

[0063] Step 5. The center coordinates and radius of each measuring position are calculated based on the real data, angle data and the measurement data of the linear displacement sensor M2. According to the corresponding relationship between the center coordinates and radius of each measuring position and the geometric parameters of the crankshaft 1, the geometric parameters of the crankshaft 1 are calculated, which are specifically:

[0064] Step 51, filter the real data to filter out the inherent frequency noise of the equipment, specifically: select a measurement position, perform FFT fast Fourier transform on the real data of the measurement position, convert it into frequency domain data, remove the high-frequency components in the frequency domain, and then perform iFFT inverse transform to convert it back to time domain data, complete the filter calculation of the measurement position, and repeat this step until the filter calculation of each measurement position is completed;

[0065] Step 52, select a measurement position, match the real data with the angle data one by one, obtain multiple points of the measurement position, perform coordinate conversion on all points, convert the polar coordinate system to the rectangular coordinate system, combine the measurement data of the linear displacement sensor M2, obtain the coordinates of all points of the measurement position in the rectangular coordinate system, repeat this step until the coordinates of all points of all measurement positions in the rectangular coordinate system are obtained;

[0066] Step 53, select a measurement position, perform least squares fitting of a circle on all points of the measurement position in the rectangular coordinate system, obtain the center coordinates and radius of the measurement position, and repeat this step until the center coordinates and radius of all measurement positions are obtained;

[0067] Step 54: Calculate the geometric parameters of the crankshaft 1 based on the corresponding relationship between the center coordinates and radius of each measuring position and the geometric parameters of the crankshaft 1.

[0068] In this embodiment, Figure 2 As shown, 8 measurement positions are preset, denoted as Z0 to Z7, and are set in pairs on the spline side cylinder C1, the spline side eccentric shaft C2, the non-spline side eccentric shaft C3, and the non-spline side cylinder C4. It can be understood that in order to ensure the measurement effect, Z0 and Z1 should evenly divide the spline side cylinder C1, Z2 and Z3 should evenly divide the spline side eccentric shaft C2, Z4 and Z5 should evenly divide the non-spline side eccentric shaft C3, and Z6 and Z7 should evenly divide the non-spline side cylinder C4.

[0069] like Figure 4 As shown, the contact position sensor M1 moves up and down in the vertical direction driven by the drive system, and the linear displacement sensor M2 can measure the vertical position of the contact displacement sensor M1. The drive system can accurately stop at each position Z0 to Z7. When the contact displacement sensor M1 moves up and down, the drive system moves the contact displacement sensor M1 to the retracted position ( Figure 2 When the contact displacement sensor M1 reaches the preset 8 measurement positions, the drive system moves the contact displacement sensor M1 to the extended position ( Figure 2 At Q1 in the middle, the probe of the contact displacement sensor M1 contacts the crankshaft 1 of the part.

[0070] At each measuring position, the pin G drives the crankshaft 1 to rotate at a constant speed around the axis. During one rotation, the values ​​of the absolute angles M3 and M1 of the crankshaft 1 are collected at equal time intervals to obtain displacement data and angle data. The time interval and rotation speed determine the sampling amount. By repeating this process, a total of 8 groups of displacement data and 8 groups of angle data corresponding to Z0~Z7 can be obtained. Similarly, due to relative motion, a linear sensor M2 is also required to collect the vertical position of M1. Among them, the contact displacement sensor M1, the linear sensor M2 and the angle sensor M3 for measuring the rotation angle of the crankshaft 1 are all absolute sensors, which can obtain absolute values. However, the present application is not limited to the use of absolute sensors, and incremental sensors with reference points can also meet the measurement requirements.

[0071] Taking a certain moment at the Z0 position as an example, the collected data set is (contact displacement sensor value M1-0, angle sensor value M3-0), such as Figure 5 As shown, each value in M1-0 is the distance from each point in the circumferential direction of the crankshaft 1 to the probe origin O2 during the rotation process, that is, e2 in the figure, and the data actually to be measured is the real data (the distance from the probe to the rotation center O1), that is, e3 in the figure. In order to obtain the real data, the calibration distance must be obtained first, that is, e1 in the figure, and then the displacement data is subtracted from the calibration distance to obtain the real data. As for the angle data, after determining an initial position W on the crankshaft 1, the rotation angle θ of the initial position W relative to the angle sensor M3 during the rotation of the crankshaft 1 can be measured.

[0072] like Figure 6 As shown, the calibration data (H0, ..., H7) cannot be directly measured and need to be obtained through a calibration program. In this embodiment, before calibration, a calibration part that has been measured by other equipment for accurate radius data needs to be prepared. The radius data of the calibration part at Z0 is Rref0, so collecting and saving {Ref0+M1_0} can form a new data set, and the data of the data set can be averaged to obtain the value of the calibration distance H0. According to the same method, Z1, Z6 and Z7 are measured, and a total of four calibration parameters H0, H1, H6 and H7 can be obtained. The calibration distances H2, H3, H4, and H5 are not directly obtained, but are fitted by the least squares method from the four points (H0, Z0), (H1, Z1), (H6, Z6), and (H7, Z7) The straight line is obtained by substituting the values ​​of Z2~Z5 into the fitting straight line formula. After the equipment calibration is completed, the values ​​of H0~H7 are stored in the non-volatile storage medium of the control system 2 for permanent storage until the next recalibration.

[0073] After the calibration is completed, the data is processed according to the steps to obtain the diameter, eccentric circle diameter, eccentricity, coaxiality, cylindricity and other parameters of the crankshaft 1. According to the corresponding relationship between the center coordinates and radius of each measuring position and the geometric parameters of the crankshaft 1, the geometric parameters are calculated and determined as follows:

[0074] Get the center coordinates of each measurement position (O xyz -0~O xyz -7) and radius (R0~R7):

[0075] The center coordinates of the spline side cylinder C1 are (O xyz -0+O xyz -1) / 2, the radius is (R0+R1) / 2;

[0076] The center coordinates of the eccentric shaft C2 on the spline side are ( xyz -2+O xyz -3) / 2, the radius is (R2+R3) / 2;

[0077] The center coordinates of the eccentric shaft C3 on the non-spline side are (xyz -4+O xyz -5) / 2, the radius is (R4+R5) / 2;

[0078] The center coordinates of the non-spline side cylinder C4 are (O xyz -6+O xyz -7) / 2, the radius is (R6+R7) / 2;

[0079] The eccentricity of the crankshaft is the distance between the spline side eccentric shaft C2 and the non-spline side eccentric shaft C3 and the central axis, and the central axis is the line connecting the centers of the spline side cylinder C1 and the non-spline side cylinder C4;

[0080] The coaxiality of the crankshaft is O xyz -0, O xyz -1, O xyz -6, O xyz -7 The maximum distance from the central axis multiplied by 2;

[0081] The cylindricality of the crankshaft is equal to (O xyz -0~O xyz -7) The maximum value minus the minimum value of the distance to the center axis.

[0082] The following is an implementation data of this application:

[0083] 1) Collecting raw data

[0084] Execute Step 1 to Step 3. If it is the first time to execute, you also need to determine the calibration distance of each measurement position. After the acquisition is completed, the data is arranged in columns according to the sequence number index-marker point name Marker-displacement sensor value p-height value L-angle encoder data phi. Due to the problem of displacement sensor settings, the actual sampling value may be negative. When calculating, you need to take its absolute value. p is the measurement value of the contact displacement sensor M1, that is, Figure 5 The e2 and L in the figure are the measured values ​​of the linear displacement sensor M2, and phi is the measured value of the angle sensor M3. The original data is as follows. Due to the large amount of data, some measured values ​​are omitted:

[0085] ZartName:RV20E028

[0086] index, Marker, p, L, phi

[0087] 0, Z0, -20810.6, 33004.02, 0.092597655

[0088] 1, Z0, -20810.6, 33004.03, 0.092603133

[0089] 2,Z0,-20810.6,33004.03,0.092603133

[0090] 3,Z0,-20810.6,33004,0.092585602

[0091] 4,Z0,-20810.6,33004.02,0.09259875

[0092] 5,Z0,-20810.6,33004.02,0.092603133

[0093] 6,Z0,-20810.6,33004.01,0.09259875

[0094] 7,Z0,-20810.6,33004.01,0.092585602

[0095] 8,Z0,-20810.6,33004.02,0.09259875

[0096] 9,Z0,-20810.6,33004.02,0.092585602

[0097] 10,Z0,-20810.6,33004.02,0.092603133

[0098] 11,Z0,-20810.6,33004.02,0.09259875

[0099] 12,Z0,-20810.6,33004.02,0.09259875

[0100] 13,Z0,-20810.6,33004.02,0.092602037

[0101] 14,Z0,-20810.6,33004.02,0.092603133

[0102] 15,Z0,-20810.6,33004.02,0.092589985

[0103] 16,Z0,-20810.6,33004.01,0.092585602

[0104] 17,Z0,-20810.6,33004.02,0.092597655

[0105] 18,Z0,-20810.6,33004.03,0.092589985<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0106] <h2 style=";text-align:left;direction:ltr"> 19,Z0,-20810.6,33004.01,0.09259875<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0107] <h2 style=";text-align:left;direction:ltr"> 20,Z0,-20810.4,33004.02,0.094450484<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0108] <h2 style=";text-align:left;direction:ltr"> 21,Z0,-20810.3,33004.03,0.098067392<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0109] <h2 style=";text-align:left;direction:ltr"> 22,Z0,-20810.3,33004.03,0.102422801<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0110] <h2 style=";text-align:left;direction:ltr"> 23,Z0,-20810.2,33004.01,0.107009404<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"> ...<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0112] <h2 style=";text-align:left;direction:ltr"> 10156,Z7,-20819.5,71006.16,0.662792558<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0113] <h2 style=";text-align:left;direction:ltr"> 10157,Z7,-20819.5,71006.14,0.667722114<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0114] <h2 style=";text-align:left;direction:ltr"> 10158,Z7,-20819.6,71006.14,0.672629757<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0115] <h2 style=";text-align:left;direction:ltr"> 10159,Z7,-20819.6,71006.15,0.677531921<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0116] <h2 style=";text-align:left;direction:ltr"> 10160,Z7,-20819.6,71006.16,0.682339856<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0117] <h2 style=";text-align:left;direction:ltr"> 10161,Z7,-20819.7,71006.15,0.68724202<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0118] <h2 style=";text-align:left;direction:ltr"> 10162,Z7,-20819.6,71006.15,0.692042284<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0119] <h2 style=";text-align:left;direction:ltr"> 10163,Z7,-20819.6,71006.15,0.696988276<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0120] <h2 style=";text-align:left;direction:ltr"> 10164,Z7,-20819.6,71006.14,0.702118346<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0121] <h2 style=";text-align:left;direction:ltr"> 10165,Z7,-20819.6,71006.14,0.707272522<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0122] <h2 style=";text-align:left;direction:ltr">10166,Z7,-20819.6,71006.16,0.712436559<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0123] <h2 style=";text-align:left;direction:ltr"> 10167,Z7,-20819.7,71006.14,0.717548002<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0124] <h2 style=";text-align:left;direction:ltr"> 10168,Z7,-20819.6,71006.15,0.722632052<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0125] <h2 style=";text-align:left;direction:ltr"> 10169,Z7,-20819.6,71006.14,0.727673371<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0126] <h2 style=";text-align:left;direction:ltr"> 10170,Z7,-20819.6,71006.16,0.732682914<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0127] <h2 style=";text-align:left;direction:ltr"> 10171,Z7,-20819.6,71006.14,0.737676021<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0128] <h2 style=";text-align:left;direction:ltr"> 10172,Z7,-20819.7,71006.15,0.742623109<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0129] <h2 style=";text-align:left;direction:ltr"> 10173,Z7,-20819.8,71006.14,0.747569101<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0130] <h2 style=";text-align:left;direction:ltr"> 10174,Z7,-20819.8,71006.14,0.7526663<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0131] <h2 style=";text-align:left;direction:ltr"> 10175,Z7,-20819.8,71006.15,0.757840199<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0132] <h2 style=";text-align:left;direction:ltr"> 10176,Z7,-20819.8,71006.16,0.76294945<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0133] <h2 style=";text-align:left;direction:ltr"> 10177,Z7,-20819.8,71006.15,0.768035692<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0134] <h2 style=";text-align:left;direction:ltr"> 10178,Z7,-20819.8,71006.15,0.773025513<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0135] <h2 style=";text-align:left;direction:ltr"> 10179,Z7,-20819.8,71006.15,0.77804163<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0136] <h2 style=";text-align:left;direction:ltr"> 10180,Z7,-20819.7,71006.15,0.783067608<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0137] <h2 style=";text-align:left;direction:ltr"> 10181,Z7,-20819.7,71006.14,0.788049759

[0138] 2) Calculate the actual distance value

[0139] The calibration distances H0 to H7 have been calculated using calibration parts and are:

[0140] H0=28415.265430150022;

[0141] H1=28414.78629921261;

[0142] H2 = 28414.166349833478;

[0143] H3=28415.932204481185;

[0144] H4=28417.690196895641;

[0145] H5=28418.249276324481;

[0146] H6=28421.040015540086;

[0147] H7=28421.848592650462;

[0148] For each measurement position, the distance H is calibrated n (n=0-7) Subtract the displacement sensor value p of the measurement position to get the actual distance value of all positions, such as the first point of Z0 will become 28415.26-20810.6, and the last point of Z7 will become 28421.84-20819.7. In this way, the data sets P-0, P-2, ..., P-7 are obtained from the data sets M1-0, M1-1, ..., M1-7. After completion, the real data at the 8 measurement positions are obtained.

[0149] 3) Perform filtering calculation

[0150] The real data of each measurement position are filtered and calculated respectively. First, the real data is subjected to FFT fast Fourier transform to obtain the frequency domain data set, and then the high-frequency components are removed in the frequency domain and then iFFT inverse transform is performed to obtain the filtered time domain data.

[0151] 4) Convert to rectangular coordinate system

[0152] Taking the first point of Z0 as an example, the point marked by the real data + angle data is (l, ang), where l is the actual distance value of the first point at Z0, and ang is the angle value of the first point at Z0. The conversion to the rectangular coordinate system is (l*cos(ang), l*sin(ang)). Combined with the measurement data of the linear displacement sensor M2, all points are converted to obtain a new data set.

[0153] 5) Perform least squares fitting

[0154] Taking the measurement position Z0 as an example, the least squares method is used to fit multiple points to a circle in the rectangular coordinate system to obtain the coordinates of the center of the circle O xyz -0 = (x-0, y-0, z-0) and radius R0, the center coordinates and radius at the 8 measurement positions are as follows:

[0155] O xyz -0=(1.6173, 1.0284, 33004.18), R0=7602.34;

[0156] O xyz -1=(1.6195, 1.0110, 35012.58), R1=7602.06;

[0157] O xyz -2=(-851.9504, -284.9413, 40018.41), R2=11845.87;

[0158] O xyz -3=(-851.7774, -285.7959, 46006.78), R3=11845.09;

[0159] O xyz -4=(854.1788, 287.0766, 53006.79), R4=11846.12;

[0160] O xyz -5=(853.8936, 287.4504, 58006.80), R5=11845.43;

[0161] O xyz -6=(1.3125, 0.0468, 65013.44), R6=7602.62;

[0162] O xyz -7=(1.2778, -0.0562, 71006.15), R7=7601.71;

[0163] 6) Calculate the parameters of crankshaft 1

[0164] The radius of the spline side cylinder C1 is (R0+R1) / 2=7602.2, and the center is (O xyz -0+O xyz -1) / 2=(1.6184, 1.0196, 34008.38);

[0165] The radius of the eccentric circle C2 on the spline side is (R2+R3) / 2=11845.48, and the center is (O xyz -2+O xyz -3) / 2 = (-851.86, -285.36, 43012.60);

[0166] The radius of the eccentric circle C3 on the non-spline side is (R4+R5) / 2=11845.77, and the center is (O xyz -4+O xyz -5) / 2=(854.03, 287.26, 55506.79);

[0167] The radius of the non-spline side cylinder C4 is (R6+R7) / 2=7602.16, and the center is (O xyz -6+O xyz -7) / 2 = (1.2951, -0.0046, 68009.79);

[0168] The equation of the center axis of crankshaft 1 is obtained by connecting the centers of C1 and C4. The eccentricity is the distance from the centers of C2 and C3 to the center axis.

[0169] The coaxiality of the crankshaft is O xyz -0, O xyz -1, O xyz -6, O xyz -7 The maximum distance from the central axis multiplied by 2;

[0170] The cylindricality of the crankshaft is equal to (O xyz -0~O xyz -7) The maximum value minus the minimum value of the distance to the center axis.

[0171] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for detecting an ultra-high precision RV reducer crankshaft, characterized in that: It is realized based on the RV reducer crankshaft detection device, which includes a control system, a drive system, a contact displacement sensor M1, a linear displacement sensor M2 and an angle sensor M3; Specifically, the detection method includes the following steps: Step 1, the driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at a preset measuring position; Step 2, the probe of the contact displacement sensor M1 is extended and contacts the crank shaft, and the crank shaft is driven by the driving system to rotate around the axial direction. During the rotation of the crank shaft, the contact displacement sensor M1 measures the displacement data M1-n of the crank shaft relative to the measurement origin of the contact displacement sensor M1, the linear displacement sensor M2 is used to measure the position of the contact displacement sensor M1 in the vertical direction, and the angle sensor M3 measures the angle data M3-n of the crank shaft, where n is an integer used to indicate different measurement positions; Step 3, preset N+1 measurement positions, N>0, repeat Step 1 to Step 2 until the displacement data and angle data of each measurement position are obtained: {M1-n, n=0, ..., N}, {M3-n, n=0, ..., N}; Step 4. Obtain the pre-stored calibration distances of each measurement position (H0, ..., H N ), the calibration distance is the distance between the measurement origin of the contact displacement sensor M1 and the rotation center of the crankshaft, and the displacement data is subtracted from the calibration distance of each measurement position to obtain the real data {Pn, n=0, ..., N} of each measurement position; Step 5, based on the real data, the angle data and the measurement data of the linear displacement sensor M2, the center coordinates and radius of each measurement position are calculated, and the geometric parameters of the crankshaft are calculated according to the corresponding relationship between the center coordinates and radius of each measurement position and the geometric parameters of the crankshaft; Step 5 is as follows: Step 51, filter the real data to remove the inherent frequency noise of the equipment; Step 52, select a measurement position, match the real data with the angle data one by one, obtain multiple points of this measurement position, perform coordinate conversion on all points, convert from polar coordinate system to rectangular coordinate system, combine with the measurement data of linear displacement sensor M2, obtain the coordinates of all points of this measurement position in the rectangular coordinate system, repeat this step until the coordinates of all points of all measurement positions in the rectangular coordinate system are obtained; Step 53, select a measurement position, perform least squares fitting of a circle on all points of the measurement position in the rectangular coordinate system, obtain the center coordinates and radius of the measurement position, and repeat this step until the center coordinates and radius of all measurement positions are obtained; Step 54: Calculate the geometric parameters of the crankshaft based on the correspondence between the center coordinates and radius of each measuring position and the geometric parameters of the crankshaft.

2. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 1, characterized in that: Step 51 is specifically as follows: select a measurement position, perform FFT fast Fourier transform on the real data of this measurement position, convert it into frequency domain data, remove the high-frequency components in the frequency domain, and then perform iFFT inverse transform to convert it back to time domain data, complete the filtering calculation of the measurement position, and repeat this step until the filtering calculation of each measurement position is completed.

3. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 1, characterized in that: The crankshaft includes a spline K, a spline side cylinder C1, a spline side eccentric shaft C2, a non-spline side eccentric shaft C3 and a non-spline side cylinder C4 from bottom to top. The spline K, the spline side cylinder C1 and the non-spline side cylinder C4 are coaxial, and their axes are the rotation center of the crankshaft. The spline part is pressed by a pair of ejector pins G, and the driving system drives the crankshaft to rotate through the ejector pins. There are 8 preset measuring positions, denoted as Z0~Z7, which are arranged in pairs on the spline side cylinder C1, the spline side eccentric shaft C2, the non-spline side eccentric shaft C3 and the non-spline side cylinder C4.

4. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 3, characterized in that: Get the center coordinates of each measurement position (O xyz -0~O xyz -7) and radius (R0~R7): The center coordinates of the spline side cylinder C1 are (O xyz -0+O xyz -1) / 2, the radius is (R0+R1) / 2; The center coordinates of the eccentric shaft C2 on the spline side are ( xyz -2+O xyz -3) / 2, the radius is (R2+R3) / 2; The center coordinates of the eccentric shaft C3 on the non-spline side are ( xyz -4+O xyz -5) / 2, the radius is (R4+R5) / 2; The center coordinates of the non-spline side cylinder C4 are (O xyz -6+O xyz -7) / 2, the radius is (R6+R7) / 2; The eccentricity of the crankshaft is the distance between the spline side eccentric shaft C2 and the non-spline side eccentric shaft C3 and the central axis, and the central axis is the line connecting the centers of the spline side cylinder C1 and the non-spline side cylinder C4; The coaxiality of the crankshaft is O xyz -0, O xyz -1, O xyz -6, O xyz -7 The maximum distance from the central axis multiplied by 2; The cylindricality of the crankshaft is equal to (O xyz -0~O xyz -7) The maximum value minus the minimum value of the distance to the center axis.

5. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 1, characterized in that: The calibration distance of each measuring position is determined as follows: Take a part whose geometric parameters have been measured. The driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at the preset measurement position. The driving system drives the part to rotate axially. During the rotation of the part, the contact displacement sensor M1 measures the displacement data of the part relative to the measurement origin of the contact displacement sensor M1. The displacement data is added to the radius of the part at the measurement position and the average is taken to obtain the calibration distance at each measurement position.

6. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 1, characterized in that: The calibration distance of each measuring position is determined as follows: Take a part whose geometric parameters have been measured. The driving system drives the contact displacement sensor M1 to move in the vertical direction and stop at a part of the measuring position. The driving system drives the part to rotate axially. During the rotation of the part, the contact displacement sensor M1 measures the displacement data of the part relative to the measuring origin of the contact displacement sensor M1. The displacement data is added to the radius of the part at the measuring position and the average is taken to obtain the calibration distance at a part of the measuring position. The calibration distance at the remaining measurement position is obtained by fitting using the least squares method.

7. A method for detecting an ultra-high precision RV reducer crankshaft according to claim 5 or 6, characterized in that: The part is a crank shaft.

8. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 1, characterized in that: In the RV reducer crankshaft detection equipment, the driving system includes a driving motor S1, a driving motor S2 and a driving cylinder. The driving motor S1 drives the contact displacement sensor M1 to move in the vertical direction, the driving motor S2 drives the crankshaft to rotate axially, and the driving cylinder drives the contact displacement sensor M1 to extend and retract in the horizontal direction. The driving motor S1, the driving motor S2 and the driving cylinder are controlled by a control system.

9. The method for detecting an ultra-high precision RV reducer crankshaft according to claim 1, characterized in that: The RV reducer crankshaft detection equipment also includes a data acquisition system, through which the contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3 are connected to the control system, and the measurement values ​​of the contact displacement sensor M1, the linear displacement sensor M2 and the angle sensor M3 are synchronously transmitted to the control system.

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