Single-side tooth profile abrasion involute straight spur gear parameter reverse solving method based on visual inspection

Abstract

The invention relates to a single-side tooth profile wear involute straight spur gear parameter reverse solving method based on visual inspection, and the method comprises the steps: 1, obtaining a gear end surface contour point column through employing a visual inspection technology; 2, calculating a gear center point; 3, extracting a gear tooth meshing tooth profile point column and a tooth root transition curve segment point column; 4, identifying the tooth profile of the abraded gear tooth; fifthly, the tooth profiles of the abraded gear teeth are repaired; step 6, calculating the length of the common normal of the cross-k tooth; and 7, solving gear design parameters. By means of the method, under the condition that no gear design original data exist or data are lost, the worn tooth profile is recognized and repaired, then design parameters of the gear are effectively reversely solved, the worn gear is replaced, equipment scrapping caused by gear damage is avoided, the service life of equipment is prolonged, and cost is saved.

Description

Technical Field

[0001] The invention relates to a method for inversely seeking parameters of an involute spur gear with single-side tooth profile wear based on visual detection, and belongs to the technical field of inspection and testing. Background Art

[0002] As an important part in mechanical transmission, gears are widely used in reducer equipment and are in great demand, especially spur gears with involute tooth profiles. They are frequently used in various mechanical transmission equipment because of their mature production technology, high manufacturing precision, and excellent transmission performance. Influenced by the use requirements and gear lubrication, gear transmission in most cases is one-way transmission. After long-term operation, the gear teeth on the meshing side of the gear are prone to wear and fatigue pitting, resulting in gear failure. In order to ensure the normal operation of the equipment, it is necessary to replace the worn gears in time. However, in actual operation, the original design data of the gears are often lost due to poor storage management, and the purchased equipment usually does not provide the original design data, resulting in the inability to accurately obtain the design parameters of the gears, and it is difficult to process the gears consistent with the original equipment for replacement. Since gears are usually the core parts of the equipment, if the gears fail and cannot be repaired, the entire equipment will be scrapped, resulting in large economic losses.

[0003] In order to effectively obtain the gear design parameters, the existing methods usually use manual measurement methods to map the gears, and use tools such as vernier calipers to directly measure the gear's addendum circle diameter, root circle diameter, common normal length and other parameters to solve. This method is more suitable for unused gears with complete tooth profiles, but for gears that have worn on one side after long-term use, since the tooth profile is no longer a standard involute shape, and the traditional contact point measurement is difficult to accurately obtain the gear's tooth profile curve, the measurement results deviate too much from the true value of the gear, and the gear design parameters cannot be accurately obtained. With the development of visual inspection technology, it has become a trend to use non-contact measurement methods based on machine vision to measure gears, but it is currently mainly used for dimensional measurement and error detection. There is no literature on the inverse of the design parameters of gears with single-sided tooth profile wear based on visual inspection technology.

[0004] In view of the above problems, the present invention proposes a method for inversely determining the design parameters of a single-sided tooth profile worn involute spur gear based on visual detection. The method uses a high-precision camera to obtain the end face tooth profile image of the gear, uses image processing and space transformation technology to obtain the end face tooth profile curve point sequence of the gear, and performs segmentation and feature extraction on the tooth profile curve point sequence based on the gear structure principle, and effectively identifies the worn tooth profile. On this basis, the standard involute tooth profile on the unworn side is used to "repair" and reconstruct the worn side tooth profile to obtain a complete designed tooth profile, and the relationship between the gear structure parameters is used to inversely determine the gear module, pressure angle, displacement coefficient and other design parameters. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for inversely determining parameters of an involute spur gear with single-sided tooth profile wear based on visual detection.

[0006] The technical solution of the present invention is as follows:

[0007] A method for inversely determining parameters of an involute spur gear with single-sided tooth profile wear based on visual detection comprises the following steps:

[0008] Step 1: Use visual inspection technology to obtain the gear end face contour point sequence;

[0009] Step 2: Based on the gear end face contour point sequence, reconstruct the gear addendum circle and tooth root circle, and then calculate the gear center point;

[0010] Step 3, extracting the gear meshing profile point sequence and the tooth root transition curve segment point sequence from the gear end face contour point sequence;

[0011] Step 4: Based on the principle that the distance from the center point of the gear to the normal line of any point on the meshing tooth profile is a constant value, identify the worn tooth profile;

[0012] Step 5: Based on the principle that the tooth profiles on the left and right sides of the involute spur gear are symmetrical with respect to the center line of the gear teeth, repair the worn gear tooth profiles;

[0013] Step 6: Calculate the length of the common normal line across k teeth;

[0014] Step 7: Solve the gear design parameters.

[0015] Preferably, the use of visual inspection technology in step 1 refers to obtaining an end face image of the worn gear through a camera, and then filtering, binarizing and edge extracting the obtained end face image using the image processing function of MATLAB software to obtain an end face profile image point sequence of the gear {P i (u i ,v i )}(1￡i￡N), N is the number of points in the image point array, and then the image point array is transformed by using the intrinsic and extrinsic parameters obtained by camera calibration to obtain the corresponding 3D point array in the world coordinate system. Since the end face contour point array of the gear is on the same plane through the end face, and only the coordinates of the point array in the gear end face plane are involved in the inverse design parameter, the gear end face contour point array is transformed by 2D plane coordinates {Q i (x i ,y i )}(1￡i￡N) represents.

[0016] Preferably, the camera is an industrial camera with more than 25 million pixels. The advantage of this design is that in order to ensure the effect of the end face image obtained, it is not advisable to choose a camera with too low pixels.

[0017] Preferably, the step 2 comprises the following steps:

[0018] (1) Construction of initial tooth tip circle and initial tooth root circle of gear

[0019] a) Based on the gear end face contour point list {Q i (x i ,y i )}(1￡i￡N), and use formula (1) to calculate its center of gravity Use it as the initial center point of the gear;

[0020]

[0021] b) Calculate the point sequence {Q i (x i ,y i )}(1￡i￡N) from each point to the initial center point of the gear The distance corresponding to the point sequence is obtained. i}((1￡i￡N));

[0022] c) Traverse the distance set {d i}((1￡i￡N)), search for the maximum distance value d max and the minimum distance d min , with the initial center point of the gear As the center of the circle, respectively max and d min As the radius, the initial addendum circle C of the gear is obtained. a and initial tooth root circle C r ;

[0023] d) Set the distance threshold ε (2mm￡ε￡4mm); calculate the point sequence {Q i (x i ,y i )}(1￡i￡N) to the initial tooth tip circle C a The minimum distance of i ′}((1￡i￡N)), then at the point column {Q i (x i ,y i )}(1￡i￡N) to extract the distance value less than the threshold ε tooth profile points to construct the initial tooth tip circle point array

[0024] e) Calculate the point sequence {Q i(x i ,y i )}(1￡i￡N) to the initial tooth root circle C r The minimum distance of i i′}((1￡i￡N)), then in the point column {Q i (x i ,y i )}(1￡i￡N) to extract the distance value less than the threshold ε tooth profile points to construct the initial tooth root point array

[0025] (2) Gear tip circle reconstruction

[0026] a) Take the initial distance threshold of the tooth top circle reconstruction as The initial tooth tip circle point sequence extracted is fitted by the least squares circle fitting method. Perform circle fitting to obtain the fitting tooth addendum circle Its center is Calculate the point sequence sequentially Each point in the tooth to the fitting addendum circle The distance of

[0027] b) Traverse the distance set If a distance value is greater than Then the point corresponding to the distance value is removed from the point list , thereby effectively removing some non-tooth tip dots in the initial tooth tip dot array, and the remaining points constitute a new tooth tip circle point array

[0028] c) Reduce the threshold by half, (k is the number of repetitions, k = 1, 2, 3, ...), repeat steps a) and b) to fit the extracted tooth top point sequence and remove non-tooth top points according to the given threshold until the reduced threshold is (k=1,2,3,…)￡0.03mm, then extract Points composed of tooth top circle point array It can be used as the effective tooth tip circle point sequence of the gear, and the tooth tip circle obtained by fitting this point sequence is is the addendum circle of the gear, with its center is the center point of the gear, and its radius r a is the radius of the gear tooth tip circle;

[0029] (3) Gear root circle reconstruction

[0030] The method of gear root circle reconstruction is the same as that of tooth addendum circle reconstruction. The initial distance threshold of gear root circle reconstruction is Repeat step (2) several times to re-order the initial tooth root point array. Perform root circle fitting and remove non-root circle points until the reduced threshold is reached (t is the number of repetitions, t = 1, 2, 3, ...) It stops when ￡0.03mm, and the The tooth root circle point array consists of It can be used as the effective root circle point sequence of the gear, and the root circle obtained by fitting is the root circle of the gear, and its center It is also the center point of the gear, and its radius r f is the root circle radius of the gear;

[0031] (4) Calculation of gear center point

[0032] The center point of the gear is obtained by performing the above steps (2) and (3) twice. and Since the center point of the gear is unique, and Theoretically, they should be coincident points; calculate the two center points and If Δ is less than the given threshold ε Δ (0.03mm<ε Δ <0.05mm), then the center point obtained above is valid, and the midpoint of the line connecting the two center points is taken. As the center point of the gear; if Δ>ε Δ , then the center point O obtained by the above-mentioned gear addendum circle reconstruction and gear root circle reconstruction is incorrect, and the distance threshold ε should be increased and the gear center point calculation should be performed again until a valid gear center point is obtained.

[0033] Preferably, the step three comprises the following steps:

[0034] (1) Extract the overall tooth profile point sequence

[0035] The tooth top point array extracted in step 2 and tooth root dot row From the gear end face contour point list {Q i (x i ,y i )}(1￡i￡N), and remove the invalid isolated points near the addendum circle and the root circle, and the remaining N g The points are the tooth profile points of each gear tooth, thus obtaining the corrected overall tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g );

[0036] (2) Construction of meshing tooth profile boundary circle

[0037] In order to effectively identify the worn tooth profile, the non-meshing points near the tooth top and tooth root must be separated from the overall tooth profile point list {Q g (x g ,y g )}(1￡g￡N g ) is removed; in order to ensure that all non-meshing points in the overall tooth profile point sequence are removed, the intercept length of the tooth top fillet curve segment and the tooth root transition curve segment is increased; taking the correction coefficient as λ (0.1￡λ￡0.15), the distance r from the lowest point of the tooth top fillet curve and the highest point of the tooth root transition curve to the gear center is h and r l It can be obtained by the following formula (2):

[0038]

[0039] With the gear center point O as the center of the circle, h and r l As the radius, find the two boundary circles C hb and C lb , then the overall tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g ) is located on the boundary circle C hb Inside the boundary circle C lb The points outside are the involute tooth profile points of the actual meshing section of the gear, located on the boundary circle C hb Points outside the boundary circle C are useless points and are not retained. lb The points within are points on the tooth root transition curve;

[0040] (3) Extraction of gear meshing tooth profile point sequence and initial tooth root transition curve point sequence

[0041] In order to facilitate the subsequent repair of the worn tooth profile, a tooth root transition curve point sequence {T c (x c ,y c )}(c=1,2,3,…); traverse the entire tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g ), calculate each point Q in turn g (x g ,y g )(1￡g￡N g ) to the gear center point O g , if d g >r h, then the point is a point on the tooth top rounding, and it is removed as a useless point; if d g <r l , then the point is a point on the tooth root transition curve segment, and it is stored in the initial tooth root transition curve point list {T c (x c ,y c )}(c=1,2,3,…), and then in the gear tooth profile point list {Q g (x g ,y g )}(1￡g￡N g ) to remove it;

[0042] After the traversal is completed, the gear tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g ) are all deleted, and the tooth root transition curve point array is all stored in the point array {T c (x c ,y c )}(1￡c￡N c ,N c is the number of points in the point sequence), and the remaining points are composed of the tooth profile points on the actual meshing segments of each gear tooth, thus forming a gear meshing tooth profile point sequence {Q e (x e ,y e )}(1￡e￡N e ,N e is the number of remaining points);

[0043] (4) Point segmentation of each gear tooth meshing profile

[0044] Gear tooth meshing profile point sequence {Q e (x e ,y e )}(1￡e￡N e ) is composed of point sequences on the meshing tooth profile segments on both sides of each gear tooth, which are sorted and clustered, and the gear tooth to which the first group of point sequences belongs is taken as the first tooth, and the tooth sequence of the remaining gear teeth is determined in the counterclockwise direction; let the number of teeth of the gear be Z, since each gear tooth of the involute spur gear has two meshing tooth profiles on the left and right, and the two tooth profiles are symmetrical with respect to the midline of the gear tooth, 2Z groups of meshing tooth profile point sequences can be obtained, that is, the left meshing tooth profile point sequence of the Z group And the right meshing tooth profile point sequence of group Z Where w is the tooth sequence, k and l are the midpoint numbers of the meshing tooth profile points on the left and right sides of the wth tooth, respectively. wG and l wH are the number of points in the meshing tooth profile point series on the left and right sides of the w-th tooth respectively.

[0045] Preferably, the step 4 comprises the following steps:

[0046] The cubic B-spline curve interpolation method is used to interpolate the extracted 2Z group meshing tooth profile point series to obtain the left meshing tooth profile of group Z. Meshing tooth profile on the right side of group Z

[0047] (1) Take the left meshing tooth profile of the first tooth Based on the method of average parameter curve sampling, m (10￡m￡15) sampling points are extracted from the tooth profile. Find the normal line of the tooth profile at each sampling point, and calculate the distance from the center point of the gear to each normal line, get m distance values, and calculate the average value of these distance values and the root mean square error ε l ;

[0048] (2) Similarly, take the right meshing tooth profile of the first tooth. Extract m (10￡m￡15) sampling points from the tooth profile based on the average parameter curve sampling method Calculate the normal line of the tooth profile at each sampling point, and calculate the distance from the center point of the gear to each normal line. Similarly, get m distance values, and calculate the average value of these distance values. and the root mean square error ε r ;

[0049] (3) Selecting the error threshold ε d (0.05mm￡ε d ￡0.1mm), if ε l >ε d , ε r ￡ε d , then the left tooth profile is worn; if ε l ￡ε d , ε r >ε d , then the right tooth profile is worn; if ε l >ε d , ε r >ε d , it means that the tooth profiles on both sides are not involutes, which is inconsistent with the unilateral wear of the gear, and the error threshold ε needs to be increased. d Then re-test the left and right meshing tooth profiles of the first tooth; if ε l ￡ε d , ε r ￡ε d , and |ε l -ε r |>0.01, indicating the error threshold ε d Too large, need to reduce ε dAfter the value of , re-test the left and right meshing tooth profiles of the first tooth; if ε l ￡ε d , ε r ￡ε d , and |ε l -ε r |￡0.01, it means that the left and right tooth profiles of the first tooth have no wear or the wear amount is very small, and it is difficult to effectively identify the worn side. At this time, the above detection method should be used to detect the worn tooth profile of the second tooth and subsequent teeth in turn until the worn tooth profile is effectively identified and the detection is terminated;

[0050] (4) For a single-sided worn gear, all the teeth on it are worn on the same side. The sequence of the worn tooth profiles of all the teeth on the entire gear is determined based on the sequence of the identified worn tooth profiles.

[0051] Preferably, in step 4, if all the tooth profiles identified are not worn or have very little wear, no repair is required and step 6 can be performed directly.

[0052] Preferably, the step five comprises the following steps:

[0053] After the worn side tooth profile is identified, based on the principle that the tooth profiles on both sides of the gear are symmetrical relative to the gear tooth centerline, the worn side tooth profile is repaired with the involute tooth profile on the unworn side. The specific steps are as follows:

[0054] (1) For the tooth root transition curve point sequence {T c (x c ,y c )}(1￡c￡N c ), the same method as the meshing tooth profile segmentation is used for segmentation and sorting processing, and the corresponding Z group of left tooth root transition curve point series and Z group of right tooth root transition curve point series are obtained; for the convenience of processing, the tooth root transition curve point series of the same gear tooth and the meshing tooth profile point series use the same tooth sequence; the cubic B-spline curve interpolation method is used to interpolate the 2Z group of tooth root transition curve point series respectively, and the Z group of gear tooth left tooth root transition curve and the Z group of gear tooth right tooth root transition curve are obtained;

[0055] (2) In order to repair the worn tooth profile, the center line of each gear tooth must be accurately determined; for any gear tooth of an involute spur gear, the tooth root transition curves on the left and right sides are symmetrical with respect to the tooth center line, and since they do not participate in meshing, the tooth root transition curve will never be worn regardless of whether the tooth profile is worn or not. Based on this, the center line of each gear tooth can be accurately obtained; with the gear center point O as the center, and r as the center, the tooth root transition curve is symmetrical with respect to the tooth center line. f +(1mm~2mm) is the radius, and an auxiliary circle is made. Then the auxiliary circle intersects with the 2Z tooth root transition curves, and 2Z intersection points are obtained;

[0056] (3) Take the first gear tooth of the gear, connect the intersection points on the transition curves of the tooth roots on the left and right sides of the tooth, and then find the midpoint of the connecting line. The straight line passing through the midpoint of the connecting line and the center point O of the gear is the midline of the first gear tooth. Mirror the unworn meshing tooth profile of the first gear tooth along the midline and replace the worn side tooth profile of the first gear tooth. The meshing tooth profile of the worn side can be repaired. The meshing tooth profile of the repaired gear tooth has the same shape as the unworn meshing tooth profile, which is a standard involute on the same base circle.

[0057] (4) Repair the meshing tooth profiles of the remaining gear teeth on the worn side in sequence according to the method of step (3).

[0058] Preferably, the step six comprises the following steps:

[0059] In order to inversely obtain the design parameters of the gear, the normal length of the gear is calculated using the repaired gear meshing tooth profile; the number of teeth k across the gear during measurement is determined by formula (3);

[0060]

[0061] The function symbol floor in the formula means rounding down. In actual measurement, the number of teeth spanned can be k or k+1.

[0062] The steps for calculating the length of the common normal across k teeth are as follows:

[0063] (1) Theoretically, the length of the common normal line of any span k of the same gear is the same, so from the repaired gear meshing tooth profile sequence and Extract the right meshing tooth profile of the nth (1￡n￡Z-k+1) tooth arbitrarily The meshing tooth profile on the left side of the n+k-1th tooth

[0064] (2) According to the formation principle of involute gears, The normal line of any point on the circle should be tangent to the base circle. There is an intersection point, then the normal is The normal of If the normal of any point on intersect, then the normal is and The common normal of

[0065] Based on this, the over-meshing tooth profile The end point on the side away from the center of the gear is the meshing tooth profile. If the normal line is the same as the meshing tooth profile If there is an intersection point, then the normal line and and The distance between the two intersection points is the length of the gear's common normal across the k teeth. If there is no intersection, then According to the principle of equal spacing, select a point along the curve approaching the center of the gear. , and calculate the normal and Is there an intersection? If there is an intersection, the length of the common normal line of the gear across k teeth can be calculated. If there is still no intersection, then Continue to calculate points on the above until the length of the gear's normal line across k teeth is obtained.

[0066] Preferably, the step seven comprises the following steps:

[0067] According to the structural principle of involute spur gears, the relationship between the pitch circle pressure angle α and the module m can be obtained by the following formula (4):

[0068]

[0069] Where W k and W k+1 are the normal lengths of the gear across k teeth and across k+1 teeth respectively; the relationship between the gear modification coefficient χ and the module m is obtained by formula (5):

[0070]

[0071] (1) Reverse calculation of modulus m

[0072] Using the method described in step 6 above, first calculate the value of the gear's span number k, and then calculate the length W of the common normal line across the k-tooth span and the k+1-tooth span respectively. k and W k+1 ; Gear span k tooth common normal length W k The relationship between the number of teeth Z, module m, displacement coefficient χ, and pitch circle pressure angle α is determined by formula (6);

[0073] W k =m{cosα[(k-0.5)π+Z·invα]+2χ·sinα} (6)

[0074] In the formula, invα=tanα-α (the first α after the equal sign is an angle, and the second α is a radian)

[0075] Substituting equation (4) and equation (5) into equation (6), since W k+1 , W k , k, Z, r f All are known, thus obtaining an equation about the modulus m, and solving the equation can obtain the calculated value of the modulus m;

[0076] The gear module m is a standard value. Theoretically, the calculated module value should be the value in the standard module series. In actual application, due to the influence of measurement error and calculation error, the calculated module value has a certain error. Therefore, the closest standard module value is selected from the national standard GB / T1357-2008 to replace the calculated value as the gear module.

[0077] (2) Inverse calculation of the pitch circle pressure angle α

[0078] Substituting the obtained gear module m into formula (4), the calculated value of the dividing circle pressure angle α can be obtained;

[0079] The pitch circle pressure angle series usually has only six standard values: 14.5°, 20°, 22.5°, 25°, 30°, and 45°. Select the value closest to the calculated value from the six standard values ​​to replace the calculated value to obtain the pitch circle pressure angle α of the gear;

[0080] (3) Inverse calculation of displacement coefficient χ

[0081] Substituting the gear module m obtained by inverse calculation into formula (5), the gear modification coefficient χ can be effectively obtained.

[0082] A computer-readable storage medium stores a computer program, which, when executed by a processor, performs the steps of the method for inversely determining parameters of an involute spur gear with single-sided tooth profile wear based on visual detection.

[0083] A device for inversely calculating the parameters of an involute spur gear with single-side tooth profile wear based on visual detection, comprising:

[0084] Memory, for storing software applications,

[0085] The processor is used to execute the software application program, and each program of the software application program correspondingly executes each step of the method for inversely determining parameters of an involute spur gear with single-sided tooth profile wear based on visual detection.

[0086] Technical features and beneficial effects of the present invention:

[0087] 1. The present invention proposes for the first time a method for inversely determining the design parameters of an involute spur gear with a single-sided tooth profile wear. This method can be used to identify and repair the worn tooth profile in the absence of original gear design data or when the data is lost. The design parameters of the gear can then be effectively inversely determined, and the worn gear can be replaced, thereby avoiding equipment scrapping due to gear damage, thereby extending the service life of the equipment and saving costs.

[0088] 2. The gear design parameter inverse method proposed in the present invention is not only applicable to standard involute spur gears, but also to displacement gears which are the most widely used but rarely involved in existing detection methods. The method used in the present invention is not only applicable to equal displacement gears, but also to unequal displacement gears (there is no relevant literature at present), which effectively ensures the universality of the method.

[0089] 3. The present invention adopts a non-contact visual detection method, and all analysis and calculations are implemented by programming. Compared with the existing commonly used contact detection method, it is less affected by the operation mode and the technical level of the operator. Not only the detection efficiency is effectively improved, but also the advantages of accuracy and stability are more obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 It is a schematic diagram of converting the gear end face tooth profile image point array into a plane point array;

[0091] Figure 2 This is a schematic diagram for calculating the center point of the gear;

[0092] Figure 3 It is a schematic diagram of the point array segmentation of the overall tooth profile of the gear;

[0093] Figure 4 This is a schematic diagram of the tooth profile of an unworn gear;

[0094] Figure 5 Schematic diagram of worn gear tooth profile;

[0095] Figure 6 This is a schematic diagram of repairing the worn gear tooth profile;

[0096] Figure 7 This is a schematic diagram for calculating the length of the common normal line across k teeth;

[0097] Figure 8 The inverse flow chart of the design parameters of the involute spur gear with single-sided tooth profile wear; DETAILED DESCRIPTION

[0098] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0099] Embodiment 1:

[0100] Reference Figure 8 As shown, this embodiment provides a method for inversely determining parameters of an involute spur gear with single-sided tooth profile wear based on visual detection, comprising the following steps:

[0101] Step 1: Use visual inspection technology to obtain the gear end face contour point sequence;

[0102] Combination Figure 1Understand that the use of visual inspection technology means obtaining the end face image of the worn gear through an industrial camera with more than 25 million pixels, and then using the image processing function of MATLAB software to filter, binarize and extract the edge of the acquired end face image to obtain the end face contour image point sequence of the gear {P i (u i ,v i )}(1￡i￡N), N is the number of points in the image point array, and then the image point array is transformed by using the intrinsic and extrinsic parameters obtained by camera calibration to obtain the corresponding 3D point array in the world coordinate system. Since the end face contour point array of the gear is on the same plane through the end face, and only the coordinates of the point array in the gear end face plane are involved in the inverse design parameter, the gear end face contour point array is transformed by 2D plane coordinates {Q i (x i ,y i )}(1￡i￡N) represents.

[0103] Step 2: Based on the gear end face contour point sequence, reconstruct the gear addendum circle and tooth root circle, and then calculate the gear center point; Figure 2 understand;

[0104] (1) Construction of initial tooth tip circle and initial tooth root circle of gear

[0105] a) Based on the gear end face contour point list {Q i (x i ,y i )}(1￡i￡N), and use formula (1) to calculate its center of gravity Use it as the initial center point of the gear;

[0106]

[0107] b) Calculate the point sequence {Q i (x i ,y i )}(1￡i￡N) from each point to the initial center point of the gear The distance corresponding to the point sequence is obtained. i}((1￡i￡N));

[0108] c) Traverse the distance set {d i}((1￡i￡N)), search for the maximum distance value d max and the minimum distance d min , with the initial center point of the gear As the center of the circle, respectively max and d min As the radius, the initial addendum circle C of the gear is obtained. a and initial tooth root circle C r ;

[0109] d) Set the distance threshold ε (2mm￡ε￡4mm); calculate the point sequence {Q i (x i ,y i )}(1￡i￡N) to the initial tooth tip circle C a The minimum distance of i ′}((1￡i￡N)), then at the point column {Q i (x i ,y i )}(1￡i￡N) to extract the distance value less than the threshold ε tooth profile points to construct the initial tooth tip circle point array

[0110] e) Calculate the point sequence {Q i (x i ,y i )}(1￡i￡N) to the initial tooth root circle C r The minimum distance of i}((1￡i￡N)), then in the point column {Q i (x i ,y i )}(1￡i￡N) to extract the distance value less than the threshold ε tooth profile points to construct the initial tooth root point array

[0111] (2) Gear tip circle reconstruction

[0112] a) Take the initial distance threshold of the tooth top circle reconstruction as The initial tooth tip circle point sequence extracted is fitted by the least squares circle fitting method. Perform circle fitting to obtain the fitting tooth addendum circle Its center is Calculate the point sequence sequentially From each point to the fitting circle The distance of

[0113] b) Traverse the distance set If a distance value is greater than Then the point corresponding to the distance value is removed from the point list , thereby effectively removing some non-tooth tip dots in the initial tooth tip dot array, and the remaining points constitute a new tooth tip circle point array

[0114] c) Reduce the threshold by half, (k is the number of repetitions, k = 1, 2, 3, ...), repeat steps a) and b) to fit the extracted tooth top point sequence and remove non-tooth top points according to the given threshold until the reduced threshold is , then extract the Points composed of tooth top circle point array It can be used as the effective tooth tip circle point sequence of the gear, and the tooth tip circle obtained by fitting this point sequence is is the addendum circle of the gear, with its center is the center point of the gear, and its radius r a is the radius of the gear tooth tip circle;

[0115] (3) Gear root circle reconstruction

[0116] The method of gear root circle reconstruction is the same as that of tooth addendum circle reconstruction. The initial distance threshold of gear root circle reconstruction is Repeat step (2) several times to re-order the initial tooth root point array. Perform root circle fitting and remove non-root circle points until the reduced threshold is reached (t is the number of repetitions, t = 1, 2, 3, ...) It stops when ￡0.03mm, and the The tooth root circle point array consists of It can be used as the effective root circle point sequence of the gear, and the root circle obtained by fitting is the root circle of the gear, and its center It is also the center point of the gear, and its radius r f is the root circle radius of the gear;

[0117] (4) Calculation of gear center point

[0118] The center point of the gear is obtained by performing the above steps (2) and (3) twice. and Since the center point of the gear is unique, and Theoretically, they should be coincident points; calculate the two center points and If Δ is less than the given threshold ε Δ (0.03mm<ε Δ <0.05mm), then the center point obtained above is valid, and the midpoint of the line connecting the two center points is taken. As the center point of the gear; if Δ>ε Δ , then the center point O obtained by the above-mentioned gear addendum circle reconstruction and gear root circle reconstruction is incorrect, and the distance threshold ε should be increased and the gear center point calculation should be performed again until a valid gear center point is obtained.

[0119] Step 3: Extract the gear meshing profile point sequence and the tooth root transition curve segment point sequence from the gear end face contour point sequence; Figure 3 understand;

[0120] (1) Extract the overall tooth profile point sequence

[0121] The tooth top point array extracted in step 2 and tooth root dot row From the gear end face contour point list {Q i (x i ,y i )}(1￡i￡N), and remove the invalid isolated points near the addendum circle and the root circle, and the remaining N g The points are the tooth profile points of each gear tooth, thus obtaining the corrected overall tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g );

[0122] (2) Construction of meshing tooth profile boundary circle

[0123] In order to ensure the constant instantaneous transmission ratio, the end face tooth profile of the involute spur gear adopts an involute, but the tooth profile after wear is no longer an involute, which is the basis for effectively identifying the worn tooth profile of the gear. Affected by gear structural factors such as tooth top rounding and gear transition curve, the tooth profile near the tooth top and tooth root is usually not an involute, and does not participate in meshing during the transmission process, but the tooth profile of the actual meshing section of the gear should be an involute.

[0124] In order to effectively identify the worn tooth profile, the non-meshing points near the tooth top and tooth root must be removed from the overall tooth profile point list {Q g (x g ,y g )}(1￡g￡N g ) is removed; in order to ensure that all non-meshing points in the tooth profile point sequence are removed, the intercept length of the tooth top fillet curve segment and the tooth root transition curve segment is increased; the correction coefficient is taken as λ (0.1￡λ￡0.15), then the distance r from the lowest point of the tooth top fillet curve (the farthest point from the tooth top circle) and the highest point of the tooth root transition curve (the farthest point from the tooth root circle) to the gear center h and r l It can be obtained by the following formula (2):

[0125]

[0126] With the gear center point O as the center of the circle, h and r l As the radius, find the two boundary circles C hb and C lb , then the overall tooth profile point sequence {Qg (x g ,y g )}(1￡g￡N g ) is located on the boundary circle C hb Inside the boundary circle C lb The points outside are the involute tooth profile points of the actual meshing section of the gear, located on the boundary circle C hb Points outside the boundary circle C are useless points and are not retained. lb The points within are points on the tooth root transition curve;

[0127] (3) Extraction of gear meshing tooth profile point sequence and initial tooth root transition curve point sequence

[0128] In order to facilitate the subsequent repair of the worn tooth profile, a tooth root transition curve point sequence {T c (x c ,y c )}(c=1,2,3,…); traverse the entire tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g ), calculate each point Q in turn g (x g ,y g )(1￡g￡N g ) to the gear center point O g , if d g >r h , then the point is a point on the tooth top rounding, and it is removed as a useless point; if d g <r l , then the point is a point on the tooth root transition curve segment, and it is stored in the initial tooth root transition curve point list {T c (x c ,y c )}(c=1,2,3,…), and then in the overall tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g ) to remove it;

[0129] After the traversal is completed, the overall tooth profile point sequence {Q g (x g ,y g )}(1￡g￡N g ) are all deleted, and the tooth root transition curve point array is all stored in the point array {T c (x c ,y c )}(1￡c￡N c ,N cis the number of points in the point sequence), and the remaining points are composed of the tooth profile points on the actual meshing segments of each gear tooth, thus forming a gear meshing tooth profile point sequence {Q e (x e ,y e )}(1￡e￡N e ,N e is the number of remaining points);

[0130] (4) Point segmentation of each gear tooth meshing profile

[0131] Gear tooth meshing profile point sequence {Q e (x e ,y e )}(1￡e￡N e ) is composed of point sequences on the meshing tooth profile segments on both sides of each gear tooth, which are sorted and clustered in a conventional manner, and the gear tooth to which the first group of point sequences belongs is taken as the first tooth, and the tooth sequence of the remaining gear teeth is determined in the counterclockwise direction; let the number of teeth of the gear be Z, since each gear tooth of the involute spur gear has two meshing tooth profiles on the left and right, and the two tooth profiles are symmetrical with respect to the midline of the gear tooth, 2Z groups of meshing tooth profile point sequences can be obtained, that is, the left meshing tooth profile point sequence of the Z group And the right meshing tooth profile point sequence of group Z Where w is the tooth sequence, k and l are the midpoint numbers of the meshing tooth profile points on the left and right sides of the wth tooth, respectively. wG and l wH are the number of points in the meshing tooth profile point series on the left and right sides of the w-th tooth respectively.

[0132] Step 4: Based on the principle that the distance from the center point of the gear to the normal line of any point on the meshing tooth profile is a constant, identify the worn tooth profile; Figure 4 and Figure 5 understand;

[0133] The cubic B-spline curve interpolation method is used to interpolate the extracted 2Z group meshing tooth profile point series to obtain the left meshing tooth profile of group Z. Meshing tooth profile on the right side of group Z According to the properties of the involute, that is, the normal line at any point on the involute must be tangent to its base circle, it can be seen that when the gear teeth are not worn, the meshing tooth profile is an involute, and the distance from the center point O of the gear to the normal line at any point on the meshing tooth profile is a constant value (base circle radius). However, after the tooth profile is worn, it is no longer an involute, so the distance from the center point O of the gear to the meshing tooth profile is no longer a constant value, but fluctuates greatly with the degree of wear. Based on this principle, the following steps can be used to effectively identify the tooth profile on the worn side of the gear:

[0134] (1) Take the left meshing tooth profile of the first tooth Based on the method of average parameter curve sampling, m (10￡m￡15) sampling points are extracted from the tooth profile. Find the normal line of the tooth profile at each sampling point, and calculate the distance from the center point of the gear to each normal line, get m distance values, and calculate the average value of these distance values and the root mean square error ε l ;

[0135] (2) Similarly, take the right meshing tooth profile of the first tooth. Extract m (10￡m￡15) sampling points from the tooth profile based on the average parameter curve sampling method Calculate the normal line of the tooth profile at each sampling point, and calculate the distance from the center point of the gear to each normal line. Similarly, get m distance values, and calculate the average value of these distance values. and the root mean square error ε r ;

[0136] (3) Selecting the error threshold ε d (0.05mm￡ε d ￡0.1mm), if ε l >ε d , ε r ￡ε d , then the left tooth profile is worn; if ε l ￡ε d , ε r >ε d , then the right tooth profile is worn; if ε l >ε d , ε r >ε d , it means that the tooth profiles on both sides are not involutes, which is inconsistent with the unilateral wear of the gear, and the error threshold ε needs to be increased. d Then re-test the left and right meshing tooth profiles of the first tooth; if ε l ￡ε d , ε r ￡ε d , and |ε l -ε r |>0.01, indicating the error threshold ε d Too large, need to reduce ε d After the value of , re-test the left and right meshing tooth profiles of the first tooth; if ε l ￡ε d , ε r ￡ε d , and |ε l -ε r|￡0.01, it means that the left and right tooth profiles of the first tooth have no wear or the wear amount is very small, and it is difficult to effectively identify the worn side. At this time, the above detection method should be used to detect the worn tooth profile of the second tooth and subsequent teeth in turn until the worn tooth profile is effectively identified and the detection is terminated;

[0137] (4) For a single-sided worn gear, all the teeth on it are worn on the same side. The position sequence of the worn tooth profiles of all the teeth on the entire gear is determined based on the position sequence (position sequence: an abbreviation for position sequence, which refers to whether the identified worn tooth profile is located on the left or right side of the tooth).

[0138] In exceptional cases, if all the tooth profiles identified have no wear or very little wear, no repair is required and you can proceed directly to step six.

[0139] Step 5: Based on the principle that the tooth profiles on the left and right sides of the involute spur gear are symmetrical relative to the center line of the gear teeth, repair the worn gear tooth profiles; Figure 6 understand;

[0140] After identifying the worn side tooth profile, based on the principle that the tooth profiles on both sides of the gear are symmetrical with respect to the center line of the gear teeth, the worn side tooth profile is repaired with the involute tooth profile on the unworn side. The specific steps are as follows:

[0141] (1) For the tooth root transition curve point sequence {T c (x c ,y c )}(1￡c￡N c ), the same method as the meshing tooth profile segmentation is used for segmentation and sorting processing, and the corresponding Z group of left tooth root transition curve point series and Z group of right tooth root transition curve point series are obtained; for the convenience of processing, the tooth root transition curve point series of the same gear tooth and the meshing tooth profile point series use the same tooth sequence; the cubic B-spline curve interpolation method is used to interpolate the 2Z group of tooth root transition curve point series respectively, and the Z group of gear tooth left tooth root transition curve and the Z group of gear tooth right tooth root transition curve are obtained;

[0142] (2) In order to repair the worn tooth profile, the center line of each gear tooth must be accurately determined; for any gear tooth of an involute spur gear, the tooth root transition curves on the left and right sides are symmetrical with respect to the tooth center line, and since they do not participate in meshing, the tooth root transition curve will never be worn regardless of whether the tooth profile is worn or not. Based on this, the center line of each gear tooth can be accurately obtained; with the gear center point O as the center, and r as the center, the tooth root transition curve is symmetrical with respect to the tooth center line. f +(1mm~2mm) is the radius, and an auxiliary circle is made. Then the auxiliary circle intersects with the 2Z tooth root transition curves, and 2Z intersection points are obtained;

[0143] (3) Take the first gear tooth of the gear, connect the intersection points on the transition curves of the tooth roots on the left and right sides of the tooth, and then find the midpoint of the connecting line. The straight line passing through the midpoint of the connecting line and the center point O of the gear is the midline of the first gear tooth. Mirror the unworn meshing tooth profile of the first gear tooth along the midline and replace the worn side tooth profile of the first gear tooth. The meshing tooth profile of the worn side can be repaired. The meshing tooth profile of the repaired gear tooth has the same shape as the unworn meshing tooth profile, which is a standard involute on the same base circle.

[0144] (4) Repair the meshing tooth profiles of the remaining gear teeth on the worn side in sequence according to the method of step (3).

[0145] Step 6: Calculate the length of the common normal line across k teeth; Figure 7 understand;

[0146] On the gear end face, the gear's normal length W k It refers to the distance between parallel straight lines tangent to the tooth profiles on opposite sides of two teeth separated by k. It is an important parameter of the gear and is related to the design parameters such as the pitch circle pressure angle α, module m and displacement coefficient χ of the gear. In order to inversely calculate the design parameters of the gear, the normal length of the gear is calculated using the repaired gear meshing tooth profile. The recommended number of teeth k for gear measurement is determined by formula (3);

[0147]

[0148] The function symbol floor in the formula means rounding down. In actual measurement, the number of teeth spanned can be k or k+1.

[0149] The steps for calculating the length of the common normal across k teeth are as follows:

[0150] (1) Theoretically, the length of the common normal line of any span k of the same gear is the same, so from the repaired gear meshing tooth profile sequence and Extract the right meshing tooth profile of the nth (1￡n￡Z-k+1) tooth arbitrarily The meshing tooth profile on the left side of the n+k-1th tooth

[0151] (2) According to the formation principle of involute gears, The normal line of any point on the circle should be tangent to the base circle. There is an intersection point, then the normal is The normal of If the normal of any point on intersect, then the normal is and The common normal of

[0152] Based on this, the over-meshing tooth profile The end point on the side away from the center of the gear is the meshing tooth profile. If the normal line is the same as the meshing tooth profile If there is an intersection point, then the normal line and and The distance between the two intersection points is the length of the gear's common normal across k teeth. If there is no intersection, then According to the principle of equal spacing, select a point along the curve approaching the center of the gear. , and calculate the normal and Is there an intersection? If there is an intersection, the length of the common normal line of the gear across k teeth can be obtained according to the above method. If there is still no intersection, then Continue to select points and calculate according to the above method until the length of the gear's normal line across k teeth is obtained.

[0153] Step 7: Solve the gear design parameters;

[0154] The design parameters of involute spur gears include the number of teeth Z, module m, pitch circle pressure angle α, and tooth top height coefficient h. a * , head clearance coefficient c * And the displacement coefficient χ, according to the national standard GB / T 1356-2001, we know that: h a * =1, c * =0.25, and the number of teeth Z of the gear can be obtained intuitively without calculation, so there are only three design parameters that need to be inversely calculated, namely, the module m, the pitch circle pressure angle α and the displacement coefficient χ; According to the structural principle of involute spur gears, the relationship between the pitch circle pressure angle α and the module m can be obtained by the following formula (4):

[0155]

[0156] Where W k and W k+1 are the normal lengths of the gear across k teeth and across k+1 teeth respectively; the relationship between the gear modification coefficient χ and the module m is obtained by formula (5):

[0157]

[0158] (1) Reverse calculation of modulus m

[0159] Using the method described in step 6 above, first calculate the value of the gear's span number k, and then calculate the length W of the common normal line across the k-tooth span and the k+1-tooth span respectively. k and W k+1 ; Gear span k tooth common normal length W k The relationship between the number of teeth Z, module m, displacement coefficient χ, and pitch circle pressure angle α is determined by formula (6);

[0160] W k =m{cosα[(k-0.5)π+Z·invα]+2χ·sinα} (6)

[0161] In the formula, invα=tanα-α (the first α after the equal sign is an angle, and the second α is a radian)

[0162] Substituting equation (4) and equation (5) into equation (6), since W k+1 , W k , k, Z, r f All are known, thus obtaining an equation about the modulus m, and solving the equation can obtain the calculated value of the modulus m;

[0163] The gear module m is a standard value. Theoretically, the calculated module value should be the value in the standard module series. In actual application, due to the influence of measurement error and calculation error, the calculated module value has a certain error. Therefore, the closest standard module value is selected from the national standard GB / T1357-2008 to replace the calculated value as the gear module.

[0164] (2) Inverse calculation of the pitch circle pressure angle α

[0165] Substituting the obtained gear module m into formula (4), the calculated value of the dividing circle pressure angle α can be obtained;

[0166] Since gear machining usually uses standardized tools, in order to reduce the number of tools, the pitch circle pressure angle series usually has only six standard values ​​of 14.5°, 20°, 22.5°, 25°, 30°, and 45°. Just like the inverse calculation of the module m, the value closest to the calculated value is selected from the six standard values ​​to replace the calculated value to obtain the pitch circle pressure angle α of the gear;

[0167] (3) Inverse calculation of displacement coefficient χ

[0168] Substituting the gear module m obtained by inverse calculation into formula (5), the gear modification coefficient χ can be effectively obtained.

[0169] Embodiment 2:

[0170] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the method for inversely determining parameters of a single-sided tooth profile worn involute spur gear based on visual detection as described in Example 1.

[0171] Embodiment 3:

[0172] A device for inversely calculating the parameters of an involute spur gear with single-side tooth profile wear based on visual detection, comprising:

[0173] Memory, for storing software applications,

[0174] The processor is used to execute the software application, and each program of the software application correspondingly executes each step of the method for inverse determination of parameters of involute spur gears with single-sided tooth profile wear based on visual detection as described in Example 1.

[0175] The above description is only a specific implementation mode of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for inversely determining parameters of involute spur gears with single-sided tooth profile wear based on visual inspection, characterized in that: The following steps are involved: Step 1: Use visual inspection technology to obtain the gear end face contour point sequence; Step 2: Based on the gear end face contour point sequence, reconstruct the gear addendum circle and tooth root circle, and then calculate the gear center point; Step 3, extracting the gear meshing profile point sequence and the tooth root transition curve segment point sequence from the gear end face contour point sequence; Step 4: Based on the principle that the distance from the center point of the gear to the normal line of any point on the meshing tooth profile is a constant value, identify the worn tooth profile; Step 5: Based on the principle that the tooth profiles on the left and right sides of the involute spur gear are symmetrical with respect to the center line of the gear teeth, repair the worn gear tooth profiles; Step 6: Calculate the length of the common normal line across k teeth; Step 7: Solve the gear design parameters.

2. The method for inversely determining parameters of a single-sided tooth profile worn involute spur gear based on visual detection as claimed in claim 1, characterized in that: The visual inspection technology in step 1 refers to obtaining the end face image of the worn gear through a camera, and then filtering, binarizing and edge extraction processing are performed on the obtained end face image using the image processing function of MATLAB software to obtain the end face profile image point sequence of the gear {P i (u i ,v i )}(1≤i≤N), N is the number of points in the image point array, and then the image point array is transformed by using the intrinsic and extrinsic parameters obtained by camera calibration to obtain the corresponding 3D point array in the world coordinate system. Since the end face contour point array of the gear is on the same plane through the end face, and only the coordinates of the point array in the gear end face plane are involved in the inverse design parameter, the gear end face contour point array is transformed by 2D plane coordinates {Q i (x i ,y i )}(1≤i≤N) represents.

3. The method for inversely determining parameters of a single-sided tooth profile worn involute spur gear based on visual detection as claimed in claim 2, characterized in that: The step 2 comprises the following steps: (1) Construction of initial tooth tip circle and initial tooth root circle of gear a) Based on the gear end face contour point list {Q i (x i ,y i )}(1≤i≤N), and use formula (1) to calculate its center of gravity Use it as the initial center point of the gear; b) Calculate the point sequence {Q i (x i ,y i )}(1≤i≤N) from each point to the initial center point of the gear The distance corresponding to the point sequence is obtained. i }((1≤i≤N)); c) Traverse the distance set {d i }((1≤i≤N)), search for the maximum distance value d max and the minimum distance d min , with the initial center point of the gear As the center of the circle, respectively max and d min As the radius, the initial addendum circle C of the gear is obtained. a and initial tooth root circle C r ; d) Set the distance threshold ε (2mm≤ε≤4mm); calculate the point sequence {Q i (x i ,y i )}(1≤i≤N) to the initial tooth tip circle C a The minimum distance of i ′}((1≤i≤N)), then at the point column {Q i (x i ,y i )}(1≤i≤N) to extract the distance value less than the threshold ε tooth profile points to construct the initial tooth tip circle point array e) Calculate the point sequence {Q i (x i ,y i )}(1≤i≤N) to the initial tooth root circle C r The minimum distance of i }((1≤i≤N)), then at the point column {Q i (x i ,y i )}(1≤i≤N) to extract the distance value less than the threshold ε tooth profile points to construct the initial tooth root point array (2) Gear tip circle reconstruction a) Take the initial distance threshold of the tooth top circle reconstruction as The initial tooth tip circle point sequence extracted is fitted by the least squares circle fitting method. Perform circle fitting to obtain the fitting tooth addendum circle Its center is Calculate the point sequence sequentially Each point in the tooth to the fitting addendum circle The distance of b) Traverse the distance set If a distance value is greater than Then the point corresponding to the distance value is removed from the point list , thereby effectively removing some non-tooth tip dots in the initial tooth tip dot array, and the remaining points constitute a new tooth tip circle point array c) Reduce the threshold by half, (k is the number of repetitions, k = 1, 2, 3, ...), repeat steps a) and b) to fit the extracted tooth top point sequence and remove non-tooth top points according to the given threshold until the reduced threshold is , then extract the Points composed of tooth tip circle point array It can be used as the effective tooth tip circle point sequence of the gear, and the tooth tip circle obtained by fitting this point sequence is is the addendum circle of the gear, with its center is the center point of the gear, and its radius r a is the radius of the gear tooth tip circle; (3) Gear root circle reconstruction The method of gear root circle reconstruction is the same as that of tooth addendum circle reconstruction. The initial distance threshold of gear root circle reconstruction is Repeat step (2) several times to re-order the initial tooth root point array. Perform root circle fitting and remove non-root circle points until the reduced threshold is reached (t is the number of repetitions, t = 1, 2, 3, ...) ≤ 0.03 mm, then the extraction is The tooth root circle point array consists of It can be used as the effective root circle point sequence of the gear, and the root circle obtained by fitting is the root circle of the gear, and its center It is also the center point of the gear, and its radius r f is the root circle radius of the gear; (4) Calculation of gear center point The center point of the gear is obtained by performing the above steps (2) and (3) twice. and Since the center point of the gear is unique, and Theoretically, they should be coincident points; calculate the two center points and If Δ is less than the given threshold ε Δ (0.03mm<ε Δ <0.05mm), then the center point obtained above is valid, and the midpoint of the line connecting the two center points is taken. As the center point of the gear; if Δ>ε Δ , then the center point O obtained by the above-mentioned gear addendum circle reconstruction and gear root circle reconstruction is incorrect, and the distance threshold ε should be increased and the gear center point calculation should be performed again until a valid gear center point is obtained.

4. The method for inversely determining parameters of a single-sided tooth profile worn involute spur gear based on visual detection as claimed in claim 3, characterized in that: The step three comprises the following steps: (1) Extract the overall tooth profile point sequence The tooth top point array extracted in step 2 and tooth root dot row From the gear end face contour point list {Q i (x i ,y i )}(1≤i≤N), and remove the invalid isolated points near the addendum circle and the root circle, and the remaining N g The points are the tooth profile points of each gear tooth, thus obtaining the corrected overall tooth profile point sequence {Q g (x g ,y g )}(1≤g≤N g ); (2) Construction of meshing tooth profile boundary circle In order to effectively identify the worn tooth profile, the non-meshing points near the tooth top and tooth root must be separated from the overall tooth profile point list {Q g (x g ,y g )}(1≤g≤N g ) is removed; in order to ensure that all non-meshing points in the overall tooth profile point sequence are removed, the intercept length of the tooth top fillet curve segment and the tooth root transition curve segment is increased; taking the correction coefficient as λ (0.1≤λ≤0.15), the distance r from the lowest point of the tooth top fillet curve and the highest point of the tooth root transition curve to the gear center is h and r l It can be obtained by the following formula (2): With the gear center point O as the center of the circle, h and r l As the radius, find the two boundary circles C hb and C lb , then the overall tooth profile point sequence {Q g (x g ,y g )}(1≤g≤N g ) is located on the boundary circle C hb Inside the boundary circle C lb The points outside are the involute tooth profile points of the actual meshing section of the gear, located on the boundary circle C hb Points outside the boundary circle C are useless points and are not retained. lb The points within are points on the tooth root transition curve; (3) Extraction of gear meshing tooth profile point sequence and initial tooth root transition curve point sequence In order to facilitate the subsequent repair of the worn tooth profile, a tooth root transition curve point sequence {T c (x c ,y c )}(c=1,2,3,…); traverse the entire tooth profile point sequence {Q g (x g ,y g )}(1≤g≤N g ), calculate each point Q in turn g (x g ,y g )(1≤g≤N g ) to the gear center point O g , if d g >r h , then the point is a point on the tooth top rounding, and it is removed as a useless point; if d g <r l , then the point is a point on the tooth root transition curve segment, and it is stored in the initial tooth root transition curve point list {T c (x c ,y c )}(c=1,2,3,…), and then in the gear tooth profile point list {Q g (x g ,y g )}(1≤g≤N g ) to remove it; After the traversal is completed, the gear tooth profile point sequence {Q g (x g ,y g )}(1≤g≤N g ) are all deleted, and the tooth root transition curve point array is all stored in the point array {T c (x c ,y c )}(1≤c≤N c ,N c is the number of points in the point sequence), and the remaining points are composed of the tooth profile points on the actual meshing segments of each gear tooth, thus forming a gear meshing tooth profile point sequence {Q e (x e ,y e )}(1≤e≤N e ,N e is the number of remaining points); (4) Point segmentation of each gear tooth meshing profile Gear tooth meshing profile point sequence {Q e (x e ,y e )}(1≤e≤N e ) is composed of point sequences on the meshing tooth profile segments on both sides of each gear tooth, which are sorted and clustered, and the gear tooth to which the first group of point sequences belongs is taken as the first tooth, and the tooth sequence of the remaining gear teeth is determined in the counterclockwise direction; let the number of teeth of the gear be Z, since each gear tooth of the involute spur gear has two meshing tooth profiles on the left and right, and the two tooth profiles are symmetrical with respect to the midline of the gear tooth, 2Z groups of meshing tooth profile point sequences can be obtained, that is, the left meshing tooth profile point sequence of the Z group And the right meshing tooth profile point sequence of group Z Where w is the tooth sequence, k and l are the midpoint numbers of the meshing tooth profile points on the left and right sides of the wth tooth, respectively. wG and l wH are the number of points in the meshing tooth profile point series on the left and right sides of the w-th tooth respectively.

5. The method for inversely determining parameters of involute spur gears with single-sided tooth profile wear based on visual detection as claimed in claim 4, characterized in that: The step 4 comprises the following steps: The cubic B-spline curve interpolation method is used to interpolate the extracted 2Z group meshing tooth profile point series to obtain the left meshing tooth profile of group Z. Meshing tooth profile on the right side of group Z (1) Take the left meshing tooth profile of the first tooth Based on the method of average parameter curve sampling, m (10≤m≤15) sampling points are extracted from the tooth profile. Find the normal line of the tooth profile at each sampling point, and calculate the distance from the center point of the gear to each normal line, get m distance values, and calculate the average value of these distance values and the root mean square error ε l ; (2) Similarly, take the right meshing tooth profile of the first tooth. Extract m (10≤m≤15) sampling points from the tooth profile based on the average parameter curve sampling method Calculate the normal line of the tooth profile at each sampling point, and calculate the distance from the center point of the gear to each normal line. Similarly, get m distance values, and calculate the average value of these distance values. and the root mean square error ε r ; (3) Selecting the error threshold ε d (0.05mm≤ε d ≤0.1mm), if ε l >ε d , ε r ≤ε d , then the left tooth profile is worn; if ε l ≤ε d , ε r >ε d , then the right tooth profile is worn; if ε l >ε d , ε r >ε d , it means that the tooth profiles on both sides are not involutes, which is inconsistent with the unilateral wear of the gear, and the error threshold ε needs to be increased. d Then re-test the left and right meshing tooth profiles of the first tooth; if ε l ≤ε d , ε r ≤ε d , and |ε l -ε r |>0.01, indicating the error threshold ε d Too large, need to reduce ε d After the value of , re-test the left and right meshing tooth profiles of the first tooth; if ε l ≤ε d , ε r ≤ε d , and |ε l -ε r |≤0.01, it means that the left and right tooth profiles of the first tooth have no wear or the wear is very small, and it is difficult to effectively identify the worn side. At this time, the above detection method should be used to detect the worn tooth profile of the second tooth and subsequent teeth in turn until the worn tooth profile is effectively identified and the detection is terminated; (4) For a single-sided worn gear, all the teeth on it are worn on the same side. The sequence of the worn tooth profiles of all the teeth on the entire gear is determined based on the sequence of the identified worn tooth profiles.

6. The method for inversely determining parameters of a single-sided tooth profile worn involute spur gear based on visual detection as claimed in claim 5, characterized in that: The step five comprises the following steps: After identifying the worn side tooth profile, based on the principle that the tooth profiles on both sides of the gear are symmetrical with respect to the gear tooth centerline, the worn side tooth profile is repaired with the involute tooth profile on the unworn side. The specific steps are as follows: (1) For the tooth root transition curve point sequence {T c (x c ,y c )}(1≤c≤N c ), the same method as the meshing tooth profile segmentation is used for segmentation and sorting processing, and the corresponding Z group of left tooth root transition curve point series and Z group of right tooth root transition curve point series are obtained; for the convenience of processing, the tooth root transition curve point series of the same gear tooth and the meshing tooth profile point series use the same tooth sequence; the cubic B-spline curve interpolation method is used to interpolate the 2Z group of tooth root transition curve point series respectively, and the Z group of gear tooth left tooth root transition curve and the Z group of gear tooth right tooth root transition curve are obtained; (2) In order to repair the worn tooth profile, the center line of each gear tooth must be accurately determined; for any gear tooth of an involute spur gear, the tooth root transition curves on the left and right sides are symmetrical with respect to the tooth center line, and since they do not participate in meshing, the tooth root transition curve will never be worn regardless of whether the tooth profile is worn or not. Based on this, the center line of each gear tooth can be accurately obtained; with the gear center point O as the center, and r as the center, the tooth root transition curve is symmetrical with respect to the tooth center line. f +(1mm~2mm) is the radius, and an auxiliary circle is made. Then the auxiliary circle intersects with the 2Z tooth root transition curves, and 2Z intersection points are obtained; (3) Take the first gear tooth of the gear, connect the intersection points on the transition curves of the tooth roots on the left and right sides of the tooth, and then find the midpoint of the connecting line. The straight line passing through the midpoint of the connecting line and the center point O of the gear is the midline of the first gear tooth. Mirror the unworn meshing tooth profile of the first gear tooth along the midline and replace the worn side tooth profile of the first gear tooth. The meshing tooth profile of the worn side can be repaired. The meshing tooth profile of the repaired gear tooth has the same shape as the unworn meshing tooth profile, which is a standard involute on the same base circle. (4) Repair the meshing tooth profiles of the remaining gear teeth on the worn side in sequence according to the method of step (3).

7. The method for inversely determining parameters of a single-sided tooth profile worn involute spur gear based on visual detection as claimed in claim 6, characterized in that: The step six comprises the following steps: In order to inversely obtain the design parameters of the gear, the normal length of the gear is calculated using the repaired gear meshing tooth profile; the number of teeth k across the gear during measurement is determined by formula (3); The function symbol floor in the formula means rounding down. In actual measurement, the number of teeth spanned can be k or k+1. The steps for calculating the length of the common normal across k teeth are as follows: (1) Theoretically, the length of the common normal line of any span k of the same gear is the same, so from the repaired gear meshing tooth profile sequence and Extract the right meshing tooth profile of the nth (1≤n≤Z-k+1) tooth arbitrarily The meshing tooth profile on the left side of the n+k-1th tooth (2) According to the formation principle of involute gears, The normal line of any point on the circle should be tangent to the base circle. There is an intersection point, then the normal is The normal of If the normal of any point on intersect, then the normal is and The common normal of Based on this, the over-meshing tooth profile The end point on the side away from the center of the gear is the meshing tooth profile. If the normal line is the same as the meshing tooth profile If there is an intersection point, then the normal line and and The distance between the two intersection points is the length of the gear's common normal across k teeth. If there is no intersection, then According to the principle of equal spacing, select a point along the curve approaching the center of the gear. , and calculate the normal and Is there an intersection? If there is an intersection, the length of the common normal line of the gear across k teeth can be calculated. If there is still no intersection, then Continue to calculate points on the above until the length of the gear's normal line across k teeth is obtained.

8. The method for inversely determining parameters of involute spur gears with single-sided tooth profile wear based on visual detection as claimed in claim 7, characterized in that: The step seven comprises the following steps: According to the structural principle of involute spur gears, the relationship between the pitch circle pressure angle α and the module m can be obtained by the following formula (4): Where W k and W k+1 are the normal lengths of the gear across k teeth and across k+1 teeth respectively; the relationship between the gear modification coefficient χ and the module m is obtained by formula (5): (1) Reverse calculation of modulus m Using the method described in step 6 above, first calculate the value of the gear's span number k, and then calculate the length W of the common normal line across the k-tooth span and the k+1-tooth span respectively. k and W k+1 ; Gear span k tooth common normal length W k The relationship between the number of teeth Z, module m, displacement coefficient χ, and pitch circle pressure angle α is determined by formula (6); W k =m{cosα[(k-0.5)π+Z·invα]+2χ·sinα} (6) In the formula, invα=tanα-α (the first α after the equal sign is an angle, and the second α is a radian) Substituting equation (4) and equation (5) into equation (6), since W k+1 , W k , k, Z, r f All are known, thus obtaining an equation about the modulus m, and solving the equation can obtain the calculated value of the modulus m; The gear module m is a standard value. Theoretically, the calculated module value should be the value in the standard module series. In actual application, due to the influence of measurement error and calculation error, the calculated module value has a certain error. Therefore, the closest standard module value is selected from the national standard GB / T1357-2008 to replace the calculated value as the gear module. (2) Inverse calculation of the pitch circle pressure angle α Substituting the obtained gear module m into formula (4), the calculated value of the dividing circle pressure angle α can be obtained; The pitch circle pressure angle series usually has only six standard values: 14.5°, 20°, 22.5°, 25°, 30°, and 45°. Select the value closest to the calculated value from the six standard values ​​to replace the calculated value to obtain the pitch circle pressure angle α of the gear; (3) Inverse calculation of displacement coefficient χ Substituting the gear module m obtained by inverse calculation into formula (5), the gear modification coefficient χ can be effectively obtained.

9. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the method for inverse determination of parameters of a single-sided tooth profile wear involute spur gear based on visual detection as described in any one of claims 1 to 8 are performed.

10. A device for inversely determining the parameters of an involute spur gear with single-sided tooth profile wear based on visual detection, comprising: Memory, for storing software applications, A processor is used to execute the software application, and each program of the software application correspondingly executes each step of the method for inverse determination of parameters of an involute spur gear with single-sided tooth profile wear based on visual detection as described in any one of claims 1-8.

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