CN111536876B - A method for in-situ measurement of sealing surface of triple eccentric butterfly valve - Google Patents
A method for in-situ measurement of sealing surface of triple eccentric butterfly valve Download PDFInfo
- Publication number
- CN111536876B CN111536876B CN202010487818.6A CN202010487818A CN111536876B CN 111536876 B CN111536876 B CN 111536876B CN 202010487818 A CN202010487818 A CN 202010487818A CN 111536876 B CN111536876 B CN 111536876B
- Authority
- CN
- China
- Prior art keywords
- equation
- straight line
- conical surface
- conical
- data points
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000007789 sealing Methods 0.000 title claims abstract description 38
- 238000012625 in-situ measurement Methods 0.000 title claims abstract description 15
- 230000014509 gene expression Effects 0.000 claims description 17
- 238000009795 derivation Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 27
- 238000012545 processing Methods 0.000 abstract description 18
- 238000004422 calculation algorithm Methods 0.000 abstract description 6
- 238000003754 machining Methods 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- 230000008901 benefit Effects 0.000 description 5
- 238000000691 measurement method Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000010923 batch production Methods 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000007306 turnover Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
Abstract
本发明公开了一种三偏心蝶阀密封面的在位测量方法，包括：获取置于转台上待测工件外部轮廓数据点的坐标信息；对数据点的坐标信息通过最小二乘拟合建立第一空间直线方程；从第一空间直线方程中根据预设锥角选取最优母线方程；通过最优母线方程拟合得到第一圆锥面方程；获取m个拟合的中心点的坐标，将中心点的坐标代入第一圆锥面方程，得到相应的m个第二圆锥面的方程；在数据点到m个第二圆锥面的最小距离值集合中选取误差最小的集合所对应的第二圆锥面为最佳拟合圆锥曲面。通过以上算法，实现了在加工的同时进行测量，随时掌握加工误差，避免离线测量后对工件进行拆卸带来的二次加工误差。
The invention discloses an in-situ measurement method for a sealing surface of a triple eccentric butterfly valve, comprising: acquiring coordinate information of data points on the outer contour of a workpiece to be measured placed on a turntable; The space straight line equation; select the optimal generatrix equation according to the preset cone angle from the first space line equation; obtain the first conical surface equation by fitting the optimal generatrix equation; obtain the coordinates of m fitted center points, The coordinates of are substituted into the equation of the first conical surface, and the corresponding equations of m second conic surfaces are obtained; the second conical surface corresponding to the set with the smallest error is selected from the set of minimum distance values from the data point to the m second conical surfaces: Best fit conic surface. Through the above algorithm, it is possible to measure at the same time of processing, grasp the processing error at any time, and avoid the secondary processing error caused by the disassembly of the workpiece after offline measurement.
Description
Technical Field
The invention relates to the technical field of measurement, in particular to an in-place measurement method for a sealing surface of a three-eccentric center butterfly valve.
Background
The majority of current machine manufacturing processes use off-line measurement techniques. The off-line measurement method needs to be carried out on professional equipment respectively for processing and measurement, and a processed workpiece needs to be moved to measurement equipment for detection. The method is suitable for large-batch production, and has the defects of unavoidably bringing about the problems of secondary clamping error, prolonged processing period, damage to the workpiece in the turnover process and the like, and influencing the production progress and efficiency.
A common off-line measurement method includes: caliper measurement, three-coordinate measuring machine, etc. The caliper has the advantages of low price and convenient use due to the use of standardized tools such as a vernier caliper, a micrometer and a caliper gauge. However, the unique oblique conical surface structure of the triple eccentric butterfly valve causes that the maximum size from the straight edge to the oblique edge is only the distance between two points on the maximum straight edge and the maximum oblique edge, so the measurement always depends on the hand feeling of an operator, the measurement repetition precision is poor, and different measurement results of the operator have great difference. And the three eccentric zero leakage sealing needs the sealing surfaces to be in complete surface contact, and the contact part is only one line due to the size error, so that the requirement of zero leakage is difficult to realize, not to mention the requirement of realizing bidirectional zero leakage sealing. In addition, the existing three-coordinate measuring instrument cannot accurately measure the butterfly valve with a larger diameter due to size limitation; and the workpiece is required to be detached from the lathe machining workbench by using the three-coordinate measuring instrument, and the error obtained by measurement cannot be used for secondary tool compensation machining on the workpiece. After the measurement is finished, if the secondary machining is carried out, the workpiece needs to be clamped again, due to the asymmetry of the sealing surface shape of the three-eccentric center butterfly valve, a large error is inevitably generated in the secondary clamping, the secondary machining cannot be carried out even if the workpiece is clamped on a lathe again, and only the scrapping treatment can be selected for the workpiece which only slightly exceeds the error allowable range.
In-place measurement means that a workpiece is not disassembled after being machined, the workpiece is still clamped on a machine tool, the machined part is measured on the machine tool, if the measurement result is unqualified, the workpiece is directly and quickly repaired on the machine tool, secondary machining errors caused by disassembling the workpiece after offline measurement are avoided, and machining precision is further improved.
Therefore, how to adopt the in-place measurement method for the workpiece, measure while processing, grasp the processing error at any time, avoid the secondary processing error that brings to dismantle the workpiece after off-line measurement, become the problem that needs to be solved urgently.
Disclosure of Invention
In view of this, the embodiment of the present invention provides an in-situ measurement method for a sealing surface of a triple eccentric butterfly valve, so as to solve the problem of a secondary machining error caused by the adoption of offline measurement to disassemble a workpiece in the prior art.
The embodiment of the invention provides an in-place measuring method for a sealing surface of a three-eccentric center butterfly valve, which comprises the following steps:
acquiring coordinate information of an external contour data point of a workpiece to be detected, which is arranged on a rotary table;
establishing a first space linear equation for the coordinate information of the data points through least square fitting;
selecting an optimal bus equation from the first space linear equation according to a preset taper angle;
fitting through an optimal generatrix equation to obtain a first conical surface equation;
obtaining m fitted coordinates of the central point, and substituting the coordinates of the central point into the first conical surface equation to obtain corresponding m second conical surface equations; the center point is selected from a preset area in a plane where a conical vertex of the workpiece to be measured is located, the plane is parallel to the upper surface of the rotary table, the preset area is a circular area containing the conical vertex and having a radius of r, or the preset area is a square area containing the conical vertex and having a side length of r, and m is a natural number greater than or equal to 1;
and selecting the second conical surface corresponding to the set with the minimum error from the minimum distance value sets from the data points to the m second conical surfaces as the best fitting conical curved surface.
Optionally, the obtaining of the coordinate information of the external contour data point of the workpiece to be measured placed on the turntable includes: when the rotary table rotates for a preset angle, the laser sensor performs one-time acquisition operation on the workpiece to be detected; after the rotary table rotates for a circle, the laser sensor moves downwards along the Z axis by a preset distance for the next acquisition operation.
Optionally, before the establishing the first spatial straight-line equation by least-squares fitting on the coordinate information of the data points, the method further includes:
setting the optimal data meeting the requirements in the data points as standard points, and taking the rest data points as data points to be screened;
setting a relative distance deviation threshold value;
and calculating the relative distance between the data point to be screened and the standard point, wherein if the relative distance is less than or equal to the relative distance deviation threshold value, the data point to be screened is a qualified data point.
Optionally, the selecting an optimal generatrix equation from the first spatial linear equation according to the preset taper angle includes:
acquiring a direction vector of a first space linear equation;
acquiring an included angle between a first space straight line and a standard straight line according to the direction vector;
calculating the cone angle of a cone taking the first space straight line as a bus according to the included angle;
taking all first space straight lines with the cone angle ranging from 18 degrees to 23 degrees as second space straight lines;
and selecting one straight line from the second space straight lines as an optimal bus.
Optionally, obtaining the direction vector of the first spatial line equation comprises:
calculating the sum of squares of residuals of the first space linear equation;
and deriving the residual sum of squares to obtain a coefficient of a first space straight line equation and a direction vector of the first space straight line.
Optionally, obtaining m fitted coordinates of the central point, and substituting the coordinates of the central point into the first conical surface equation to obtain m corresponding second conical surface equations includes:
and substituting the equation of the second space straight line into the general equation of the first conical surface to obtain the equation of the second conical surface, wherein the equation of the second conical surface is related to the coefficient of the equation of the first space straight line.
Optionally, selecting, as the best-fit conical curved surface, the second conical surface corresponding to the set with the smallest error from the minimum distance value sets of the data points to the m second conical surfaces includes:
obtaining a general expression of the minimum distance value from the data point to the m second conical surfaces by utilizing a Lagrange multiplier method of the multivariate function conditional extremum;
substituting the data points into a general expression of the minimum distance value to obtain a minimum distance value set from the data points to m second conical surfaces;
and respectively calculating errors of the minimum distance value sets from the data points to the m second conical surfaces, and selecting the second conical surface corresponding to the minimum distance value set with the minimum error as a best-fit conical curved surface.
Optionally, the obtaining a general expression of the minimum distance values from the data points to the m second conical surfaces by using a lagrangian multiplier method of the multivariate function conditional extremum includes:
obtaining a Lagrange function according to the coordinates of the data points;
respectively deriving from Lagrange functions according to the three-dimensional coordinate parameters to obtain coordinate algebraic expressions related to the Lagrange parameters and the coordinates of the data points;
substituting the coordinate algebraic expression into the equation of the second conical surface to obtain a third conical surface equation related to the Lagrangian parameter;
obtaining a specific numerical value of the Lagrangian parameter by calculating an extreme value of the third conical surface equation;
and solving the minimum distance value from the data point to the m second conical surfaces by a coordinate algebraic expression related to the Lagrange parameter and the coordinate of the data point.
The embodiment of the invention provides an in-place measuring method for a sealing surface of a three-eccentric butterfly valve, which comprises the steps of placing a workpiece to be measured of the three-eccentric butterfly valve on a rotary table, collecting coordinate information of a sealing surface data point of the workpiece to be measured through a laser sensor, and transmitting data collected by the laser sensor to a computer through an encoder; judging whether the data points can be fitted on the conical surface or not by calculating the distance from the data points (the data points except the data points fitting the space straight line) to the conical surface; otherwise, searching the central point of the next plane, continuously fitting to obtain a conical surface, and calculating the distances from the rest data points to the conical surface to judge whether the data points can be fitted to the conical surface; repeating the above steps, fitting error till | Deltaij≤Δ00And l, the conical surface is explained as the best fitting surface.
Through the in-place measuring method of the sealing surface of the three-eccentric butterfly valve, provided by the embodiment, more complete correct measuring data of a workpiece can be obtained, so that the measuring accuracy of a measuring system is improved, and a guiding effect is provided for subsequent processing. The measuring is carried out while processing is carried out, the processing error is mastered at any time, and the secondary processing error caused by disassembling the workpiece after offline measurement is avoided.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:
FIG. 1 is a flow chart illustrating an in-situ measurement method for a sealing surface of a triple offset butterfly valve according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a relationship between collected data points and qualified data points for a sealing surface of a triple offset butterfly valve according to an embodiment of the present invention;
fig. 3 shows a flow chart of another algorithm for measuring the sealing surface of the triple offset butterfly valve in place according to the embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Currently, in-situ measurement obtains a plurality of discrete data of the processed curved surface by in-situ measurement, and according to the data, a continuous curved surface is expected to be obtained to be matched with known data, and the process is a curved surface fitting process. The surface fitting technology is widely applied to the fields of computer graphics, numerical calculation and the like. The current common surface fitting methods include: least squares, interpolation, scaling algorithms, etc.
The interpolation method is to construct an nth-order polynomial P according to the interpolation principlen(x) So that P isn(x) The data at each test point just passes through the real test point; although interpolation can retain the original data points, in general many data points are collected to reflect the actual situation to the greatest extent possible, resulting in an interpolation polynomial Pn(x) The number of times is very high, which not only increases the calculated amount, but also influences the fitting precision, and is not beneficial to the curved surface fitting of the workpiece in the actual production process of the engineering. The scaling algorithm is a direct iterative algorithm with contraction and expansion of search space as basic features, and can realize optimal fitting without providing proper initial values under the condition of simpler search space, but once the search space is complicated, the search efficiency is reduced, andand difficult to implement for multi-parameter non-linearity problems. The least squares method is to select an approximate function f (x) based on known data such that the root mean square error of the function f (x) is minimized. Although the least square fitting is not enough under the condition of reserving certain original data points, the greatest advantage of the least square fitting is that the fitting precision can be regulated and controlled, and different fitting precisions can be selected according to actual use conditions. The least square normal linear fitting curved surface is simple and direct, is convenient to operate and is beneficial to the feedback of the actual processing process.
The embodiment of the invention provides an in-place measuring method for a sealing surface of a three-eccentric center butterfly valve, which comprises the following steps of:
and step S10, acquiring coordinate information of the external contour data points of the workpiece to be measured placed on the turntable.
In this embodiment, a to-be-measured triple eccentric butterfly valve workpiece is placed on the rotary table, coordinate information of a sealing surface data point of the to-be-measured workpiece is collected through the laser sensor, and data collected by the laser sensor is transmitted to the computer through the encoder.
In step S20, a first spatial straight-line equation is established by least-squares fitting to the coordinate information of the data points.
In this embodiment, the to-be-measured triple eccentric butterfly valve workpiece rotates along with the rotary table, the laser sensor performs information acquisition on the sealing surface of the to-be-measured triple eccentric butterfly valve workpiece to obtain three-dimensional coordinate information of the sealing surface of the to-be-measured triple eccentric butterfly valve workpiece, and linear fitting is performed on data points to obtain equations of a plurality of first space straight lines.
The least squares method is to select an approximate function f (x) based on known data such that the root mean square error of the function f (x) is minimized. Although the least square fitting is not enough under the condition of reserving certain original data points, the greatest advantage of the least square fitting is that the fitting precision can be regulated and controlled, and different fitting precisions can be selected according to actual use conditions. The least square normal linear fitting curved surface is simple and direct, is convenient to operate and is beneficial to the feedback of the actual processing process.
In the embodiment, the machining error condition can be fed back in time by adopting the least square normal linear fitting curved surface under the in-place measuring condition, and technical guidance is provided for subsequent machining, so that the machining precision of the workpiece is further improved.
And step S30, selecting an optimal generatrix equation from the first space linear equation according to a preset taper angle.
In this embodiment, since the sealing surface of the to-be-measured triple offset butterfly valve workpiece is approximately a conical surface, one straight line is selected from the equations of the plurality of first spatial straight lines in step S20 as the optimal generatrix of the fitted conical surface. And selecting the optimal bus according to the cone angle between the first space linear equation and the standard straight line.
And step S40, obtaining a first conical surface equation through optimal generatrix equation fitting.
In this embodiment, a line segment and a cone angle are determined in a world coordinate system, so that a plurality of conical surfaces can be obtained, and the vertexes of the conical surfaces are not determined.
And step S50, obtaining the coordinates of m fitted central points, and substituting the coordinates of the central points into the first conical surface equation to obtain corresponding m second conical surface equations. The center point is selected from a preset area in a plane where a conical vertex of the workpiece to be measured is located, the plane is parallel to the upper surface of the rotary table, the preset area is a circular area containing the conical vertex and having a radius of r, or the preset area is a square area containing the conical vertex and having a side length of r, and m is a natural number larger than or equal to 1.
In this embodiment, the laser sensor performs data acquisition on the coordinate of the vertex of the sealing surface of the workpiece to be measured of the three-eccentric center butterfly valve, and in the process that the workpiece to be measured rotates along with the turntable, the x-axis coordinate and the y-axis coordinate of the vertex of the sealing surface of the workpiece to be measured may change, while the z-axis coordinate of the vertex of the sealing surface of the workpiece to be measured generally does not change. If the vertex of the sealing surface of the to-be-tested triple eccentric butterfly valve workpiece is just right above the center of the rotary table when the to-be-tested triple eccentric butterfly valve workpiece is placed, the coordinate of the vertex of the sealing surface of the to-be-tested workpiece cannot be changed in the rotating process of the rotary table.
Taking a circular area as an example, in any measurement process, determining a circular area with the vertex coordinate of the sealing surface as the center of a circle and r as the radius, dividing the circular area into m unit areas on average according to a preset size, selecting the center coordinate of the unit area as a fitting center point, and substituting the m fitting center point coordinates into the first conical surface equation in the step S40 to obtain m second conical surface equations. The values of the radii r and m can be set according to actual needs.
And step S60, selecting the second conical surface corresponding to the set with the minimum error from the minimum distance value sets from the data points to the m second conical surfaces as the best fitting conical curved surface.
In this embodiment, whether the data point can be fitted to the conical surface is determined by calculating the distance from the data point (the data point divided by the fitting space straight line) to the conical surface; otherwise, searching the central point of the next plane, continuously fitting to obtain a conical surface, and calculating the distances from the rest data points to the conical surface to judge whether the data points can be fitted to the conical surface; repeating the above steps, fitting error till | Deltaij≤Δ00And l, the conical surface is explained as the best fitting surface.
Through the in-place measuring method of the sealing surface of the three-eccentric butterfly valve, provided by the embodiment, more complete correct measuring data of a workpiece can be obtained, so that the measuring accuracy of a measuring system is improved, and a guiding effect is provided for subsequent processing. The measuring is carried out while processing is carried out, the processing error is mastered at any time, and the secondary processing error caused by disassembling the workpiece after offline measurement is avoided.
As an optional implementation manner, acquiring coordinate information of an external contour data point of a workpiece to be measured, which is placed on a turntable: when the rotary table rotates for a preset angle, the laser sensor performs one-time acquisition operation on the workpiece to be detected; after the rotary table rotates for a circle, the laser sensor moves downwards along the Z axis by a preset distance for the next acquisition operation.
In the embodiment, a workpiece to be measured is placed on a rotary table, the rotary table drives the workpiece to be measured to rotate at a constant speed, the laser measures data once when the workpiece to be measured rotates at the same angle, and the laser sensor completes measurement once after the workpiece rotates for one circle; and then the laser sensor moves downwards along with the Z axis by a proper distance, the laser measures data once when the workpiece rotates by the same angle, and the laser sensor finishes one measurement after rotating for one circle. Repeating the above operations to finally obtain all data points.
All measured data points are characterized by: there is one data band having the same value and another data band having the same value.
The turntable drives the workpiece to rotate at a constant speed, and data points can be divided into data point rows according to the average rotation angle.
As an optional implementation manner, before step S20, the method further includes:
and step S11, setting the optimal data meeting the requirements in the data points as standard points, and taking the rest data points as the data points to be screened.
In step S12, a relative distance deviation threshold is set.
And step S13, calculating the relative distance between the data point to be screened and the standard point, and if the relative distance is less than or equal to the relative distance deviation threshold value, the data point to be screened is a qualified data point.
In the present embodiment, the relative distance deviation is used to remove the abnormal data points; each time the measurement is completed by one circle, the data points of the group of data have two obviously different values, and the group of data with smaller values is closer to the standard value. Assuming that the acquired data point column has optimal data meeting the requirement, the optimal data is set as a standard point. As shown in fig. 2, the standard point set is set according to the above method, the relative average distance D between other data points and the standard point set is calculated, meanwhile, the relative distance deviation threshold epsilon is set according to the requirement, if D is less than or equal to epsilon, the data point meets the requirement, and finally, all the data points meeting the requirement are obtained.
As an alternative embodiment, step S30 includes:
step S301, a direction vector of the first spatial linear equation is obtained.
Step S302, acquiring and obtaining an included angle between the first space straight line and the standard straight line according to the direction vector.
And step S303, calculating the cone angle of the cone taking the first space straight line as the generatrix according to the included angle.
And step S304, taking all the first space straight lines with the cone angle ranging from 18 degrees to 23 degrees as second space straight lines.
Step S305, selecting one straight line from the second space straight lines as an optimal bus.
In the present embodiment, a straight line having a taper angle of 20 ° is selected as the optimal generatrix.
As an alternative embodiment, step S301 includes:
calculating the sum of squares of residuals of the first space linear equation;
and deriving the residual sum of squares to obtain a coefficient of a first space straight line equation and a direction vector of the first space straight line.
In this embodiment, assume that the equation of a straight line is:
wherein
The data point coordinates of the sealing surface of the three-eccentric center butterfly valve workpiece to be detected are acquired by the laser sensor.
The sum of the squares of the residuals is found to be:
Qijand Qi，j+1I.e. the optimization criterion, for QijAnd Qi，j+1Respectively obtaining the following derivatives:
the coefficients of the first spatial line equation are:
from the normal vector of the plane, the normal linear direction vector
The direction vector of the space straight line is
Then, in step S302, an included angle between the first spatial straight line and the standard straight line is obtained according to the direction vector: according to
A first spatial straight line l can be calculatedijAt an angle to the normal line of
Step S303, calculating according to the included angle to obtain a cone angle alpha of a cone taking the first space straight line as a generatrixij。
As an alternative embodiment, step S50 includes: and substituting the equation of the second space straight line into the general equation of the first conical surface to obtain the equation of the second conical surface, wherein the equation of the second conical surface is related to the coefficient of the equation of the first space straight line.
In the embodiment, the second spatial straight line is a taper angle α between the same standard straight lineijA first space straight line of 20 degrees, and a second space straight line l2：
Substituting the equation of the conical surface: g (x, y, z) ═ a2(x2+y2)-z2And the coefficient a in the equation is obtained by fitting calculation according to the data points on the second space straight line.
Obtaining a conical surface equation:
determination of the center point Cm(x, y, z), coordinate C of the center pointm(x, y, z) is substituted into the equation of the conical surface to obtain:
as an alternative embodiment, step S60 includes:
step S601, a lagrangian multiplier method of the multivariate function conditional extremum is used to obtain a general expression of the minimum distance between the data point and the m second conical surfaces.
Specifically, step S601 includes:
step S6011 obtains a Lagrangian function according to the coordinates of the data points.
The lagrange function is listed:
Lij＝(x-xij)2+(y-yij)2+(z-zij)2+λ[a2(x2+y2)-z2]
wherein (x, y, z) is a point on the conical surface, (x)ij，yij，zij) Is a second spatial straight line l2Point (c) above.
Step S6012, deriving from the Lagrangian functions according to the three-dimensional coordinate parameters respectively, and obtaining coordinate algebraic expressions related to the Lagrangian parameters and the coordinates of the data points.
Derivation of the lagrangian function in step S6011:
l 'of'x＝0，L'y＝0，L'z0, find the xyz coordinate algebraic expression for λ and the data point coordinates:
and step S6013, substituting the coordinate algebraic expression into the equation of the second conical surface to obtain a third conical surface equation related to the Lagrangian parameter.
Substituting the xyz coordinate algebraic expression in the step S6012 into the equation G (x, y, z) of the conical surface to obtain:
step S6014, the specific numerical value of the Lagrangian parameter is obtained by calculating the extreme value of the third conic equation.
The value of λ can be obtained by obtaining an extremum for G (λ).
And step S6015, the minimum distance values from the data points to the m second conical surfaces are obtained through a coordinate algebraic expression related to the Lagrangian parameter and the coordinate of the data points.
The set of known data points X e { X ═ X (X)ij,yij,zij) Calculate the spatial point (x)ij,yij,zij) Distance to the conical surface:
step S602, substituting the data point into the general expression of the minimum distance value to obtain a minimum distance value set from the data point to the m second conical surfaces.
As is known from step S6012,
and the value of λ obtained in step S6014 is substituted into the distance formula dijAnd (5) calculating the minimum value of the distances from the data points to the m second conical surfaces.
And step S603, errors are respectively calculated for the minimum distance value sets from the data points to the m second conical surfaces, and the second conical surface corresponding to the minimum distance value set with the minimum error is selected as the best fitting conical curved surface.
Order to
When deltaijAnd when the ratio is less than 0.2%, stopping iteration, and finding the best fitting conical surface.
As shown in fig. 3, the algorithm for linearly fitting the sealing surface of the triple offset butterfly valve by using the least squares under the in-place measurement condition includes the following steps:
the method comprises the following steps: during laser measurement, a workpiece is placed on a rotary table, the rotary table drives the workpiece to rotate at a constant speed, the laser measures data once when the workpiece rotates at the same angle, and after the workpiece rotates for one circle, the laser sensor completes one measurement; and then the laser sensor moves downwards along with the Z axis by a proper distance, the laser measures data once when the workpiece rotates by the same angle, and the laser sensor finishes one measurement after rotating for one circle. Repeating the above operations to finally obtain all data points. The encoder transmits the data obtained by the acquisition and measurement to the computer.
Step two: removing abnormal data points by using the relative distance deviation; each time the measurement is completed by one circle, the data points of the group of data have two obviously different values, and the group of data with smaller values is closer to the standard value. And setting a standard point set according to the method, calculating the relative average distance D between other data points and the standard point set, simultaneously setting a relative distance deviation threshold epsilon according to requirements, if D is less than or equal to epsilon, enabling the data points to meet the requirements, and finally obtaining all the data points meeting the requirements.
Step three: establishing a space linear equation of data points and performing least square fitting; finally obtaining a space straight line l by solving the optimization criterion, namely the sum of squares of residual errorsijAnd the direction vector of the straight line is
Step four: and calculating a cone angle according to the obtained space straight line, fitting to obtain a three-dimensional curved surface, and constraining the three-dimensional curved surface into a conical surface to obtain a general equation of the conical surface.
Step five: for the obtained general conic surface equation, the central point C is determinedm(x, y, z) sequentially obtaining a conical surface for further fitting; the Lagrange multiplier method of the extreme value of the multivariate function condition is utilized to solve the distance equation d between the data point set and the conical surfaceij(ii) a By calculating the distance equation d between the data point set and the conical surfaceijMean value ofijAnd judging the conical surface obtained by final fitting as an optimal solution.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (8)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010487818.6A CN111536876B (en) | 2020-06-02 | 2020-06-02 | A method for in-situ measurement of sealing surface of triple eccentric butterfly valve |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010487818.6A CN111536876B (en) | 2020-06-02 | 2020-06-02 | A method for in-situ measurement of sealing surface of triple eccentric butterfly valve |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111536876A CN111536876A (en) | 2020-08-14 |
| CN111536876B true CN111536876B (en) | 2021-07-13 |
Family
ID=71980751
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010487818.6A Active CN111536876B (en) | 2020-06-02 | 2020-06-02 | A method for in-situ measurement of sealing surface of triple eccentric butterfly valve |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111536876B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112353513B (en) * | 2020-11-05 | 2021-09-28 | 深圳市翔通光电技术有限公司 | Machining method and machining device for base station, storage medium and computer equipment |
| CN112611325B (en) * | 2020-12-07 | 2022-05-24 | 东莞市兆丰精密仪器有限公司 | Calibration method of laser center and calibration method of laser center synchronous with image center |
| CN113804121B (en) * | 2021-08-26 | 2024-05-17 | 华东师范大学 | Real-time measuring method and measuring system for profiles of multiple workpieces |
| CN116182698A (en) * | 2021-11-26 | 2023-05-30 | 中国石油天然气集团有限公司 | A blowout preventer cleaning and sealing detection device |
| CN116452527B (en) * | 2023-03-31 | 2025-08-05 | 华东理工大学 | Butterfly valve sealing surface identification method |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102537382A (en) * | 2012-02-28 | 2012-07-04 | 常州大学 | Simple and easy determining method of three-eccentric center butterfly valve seal surface dimension interference |
| CN102609566A (en) * | 2012-01-12 | 2012-07-25 | 中国石油天然气集团公司 | Optimization design method for non-API (American petroleum institute) thread sealing face |
| CN203657757U (en) * | 2013-11-19 | 2014-06-18 | 苏州慧利仪器有限责任公司 | Optical detection apparatus of hollow cylinder inner surface |
| CN105526885A (en) * | 2015-12-03 | 2016-04-27 | 郑州轻工业学院 | Taper hole cone angle high precision detection method based on composite probe |
| CN106446361A (en) * | 2016-09-08 | 2017-02-22 | 河海大学常州校区 | Tightness evaluation method of oil casing pipe screwed joint |
| CN107063132A (en) * | 2016-11-15 | 2017-08-18 | 首都航天机械公司 | A kind of space flight valve products morpheme size measuring method |
| CN108846894A (en) * | 2018-06-27 | 2018-11-20 | 燕山大学 | A kind of elliptic cone and ellipsoid parameter extracting method based on the literary Burger-Marquardt method of column |
| CN108895980A (en) * | 2018-05-23 | 2018-11-27 | 江苏理工学院 | A kind of detection device and its detection method of conical bore profile |
| CN109598779A (en) * | 2018-07-17 | 2019-04-09 | 哈尔滨工业大学（威海） | A kind of circular cone spline surface generation method for approaching given surface model |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9316493B2 (en) * | 2013-12-13 | 2016-04-19 | Siemens Energy, Inc. | Method and apparatus for determining gas turbine dampening cone inner diameter |
-
2020
- 2020-06-02 CN CN202010487818.6A patent/CN111536876B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102609566A (en) * | 2012-01-12 | 2012-07-25 | 中国石油天然气集团公司 | Optimization design method for non-API (American petroleum institute) thread sealing face |
| CN102537382A (en) * | 2012-02-28 | 2012-07-04 | 常州大学 | Simple and easy determining method of three-eccentric center butterfly valve seal surface dimension interference |
| CN203657757U (en) * | 2013-11-19 | 2014-06-18 | 苏州慧利仪器有限责任公司 | Optical detection apparatus of hollow cylinder inner surface |
| CN105526885A (en) * | 2015-12-03 | 2016-04-27 | 郑州轻工业学院 | Taper hole cone angle high precision detection method based on composite probe |
| CN106446361A (en) * | 2016-09-08 | 2017-02-22 | 河海大学常州校区 | Tightness evaluation method of oil casing pipe screwed joint |
| CN107063132A (en) * | 2016-11-15 | 2017-08-18 | 首都航天机械公司 | A kind of space flight valve products morpheme size measuring method |
| CN108895980A (en) * | 2018-05-23 | 2018-11-27 | 江苏理工学院 | A kind of detection device and its detection method of conical bore profile |
| CN108846894A (en) * | 2018-06-27 | 2018-11-20 | 燕山大学 | A kind of elliptic cone and ellipsoid parameter extracting method based on the literary Burger-Marquardt method of column |
| CN109598779A (en) * | 2018-07-17 | 2019-04-09 | 哈尔滨工业大学（威海） | A kind of circular cone spline surface generation method for approaching given surface model |
Non-Patent Citations (1)
| Title |
|---|
| 三坐标测量机在匣阀测量中的应用研究;刘紫薇等;《化学工程与装备》;20161030;参见正文168-170页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111536876A (en) | 2020-08-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111536876B (en) | A method for in-situ measurement of sealing surface of triple eccentric butterfly valve | |
| CN102483621B (en) | Machine tool calibration method | |
| EP1528355B1 (en) | Dynamic artefact comparison | |
| EP3134707B1 (en) | Calibration of measurement probes | |
| CN115922439B (en) | Machining accuracy detection method for CNC five-axis machine tools | |
| Mutilba et al. | Uncertainty assessment for on-machine tool measurement: An alternative approach to the ISO 15530-3 technical specification | |
| CN115365941A (en) | Automatic workpiece pose calibration method for optical polishing | |
| JP2023035004A (en) | Calculation method of corrected parameter of motion error in machine tool and machine tool | |
| CN118243009B (en) | Rapid detection method for roundness abnormal area of large-diameter cylinder | |
| CN117308848A (en) | Method for detecting machining precision of large-size gear | |
| JP2011206862A (en) | Method of positioning rotary tool in multishaft processing machine | |
| Buajarern et al. | Effect of step number on roundness determination using multi-step method | |
| CN108332642B (en) | Right-angle head precision detection method | |
| CN113427320A (en) | Multi-axis on-machine measurement planning method for reducing measurement uncertainty | |
| Drbul et al. | Influence of normal vectors on the accuracy of product's geometrical specification | |
| KR20220023270A (en) | Method for measuring geometric errors of vertical 5-axis machine tools | |
| WO2016034855A1 (en) | Coordinate measuring method and apparatus for inspecting workpieces, comprising generating measurement correction values using a reference shape that is known not to deviate substantially from a perfect form | |
| Khan et al. | A methodology for error characterization and quantification in rotary joints of multi-axis machine tools | |
| CN104596461B (en) | For detecting feature exemplar and the method for three axle diamond lathe positioning precisions | |
| CN109443290B (en) | Method for measuring waveform size of three-lobe wave outer raceway of bearing | |
| CN206618368U (en) | A kind of roundness measuring device | |
| Collins et al. | Alternate methods for sampling in coordinate metrology | |
| CN104596465B (en) | For detecting feature exemplar and the method for three axle diamond lathe axial system errors | |
| CN116330043A (en) | Method and system for measuring surface edge error based on constant longitude vector measurement | |
| CN116483021A (en) | A comprehensive compensation method for key errors in five-axis on-machine measurement |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |