CN115415853A - Method and system for identifying geometric error of swing head of five-axis numerical control machine tool - Google Patents
Method and system for identifying geometric error of swing head of five-axis numerical control machine tool Download PDFInfo
- Publication number
- CN115415853A CN115415853A CN202211288741.5A CN202211288741A CN115415853A CN 115415853 A CN115415853 A CN 115415853A CN 202211288741 A CN202211288741 A CN 202211288741A CN 115415853 A CN115415853 A CN 115415853A
- Authority
- CN
- China
- Prior art keywords
- machine tool
- coordinate system
- axis
- numerical control
- error
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 49
- 238000005259 measurement Methods 0.000 claims abstract description 63
- 239000011159 matrix material Substances 0.000 claims abstract description 39
- 230000009466 transformation Effects 0.000 claims abstract description 32
- 238000009434 installation Methods 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 230000008569 process Effects 0.000 claims description 12
- 230000008859 change Effects 0.000 claims description 5
- 239000013598 vector Substances 0.000 claims description 5
- 238000002474 experimental method Methods 0.000 claims description 2
- 238000001514 detection method Methods 0.000 description 10
- 238000010586 diagram Methods 0.000 description 10
- 230000006870 function Effects 0.000 description 9
- 238000000088 particle-induced gamma-ray emission spectroscopy Methods 0.000 description 9
- 238000004590 computer program Methods 0.000 description 7
- 238000012545 processing Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 230000004044 response Effects 0.000 description 4
- 238000003860 storage Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004422 calculation algorithm Methods 0.000 description 2
- NAWXUBYGYWOOIX-SFHVURJKSA-N (2s)-2-[[4-[2-(2,4-diaminoquinazolin-6-yl)ethyl]benzoyl]amino]-4-methylidenepentanedioic acid Chemical compound C1=CC2=NC(N)=NC(N)=C2C=C1CCC1=CC=C(C(=O)N[C@@H](CC(=C)C(O)=O)C(O)=O)C=C1 NAWXUBYGYWOOIX-SFHVURJKSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001900 extreme ultraviolet lithography Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
- B23Q17/24—Arrangements for observing, indicating or measuring on machine tools using optics or electromagnetic waves
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
Abstract
The invention discloses a method and a system for identifying geometric errors of a swing head of a five-axis numerical control machine tool, wherein a measuring coordinate system is established, a moving reflector on the five-axis numerical control machine tool is tracked in real time, and the distance between a machine tool measuring point and a base station and the distance between each measuring point are obtained; calibrating the position of a laser tracking interferometer base station and the three-dimensional coordinate value of a machine tool measuring point under a measuring coordinate system according to the distance, determining the measuring coordinate system, and performing homogeneous coordinate transformation with the machine tool coordinate system to obtain a homogeneous transformation matrix between the two coordinate systems; converting the three-dimensional coordinates of the measuring points in the measuring coordinate system into three-dimensional coordinates in the machine tool coordinate system; solving a measuring point space error caused by a machine tool rotating shaft geometric error under a machine tool coordinate system, determining an identification model of the rotating shaft position related geometric error, and realizing the swing head geometric error identification of the five-axis numerical control machine tool by utilizing the identification model. The invention reduces the influence of random errors on the measurement precision and improves the measurement efficiency and the measurement precision.
Description
Technical Field
The invention belongs to the technical field, and particularly relates to a method and a system for identifying a swing head geometric error of a five-axis numerical control machine tool.
Background
The precision and ultra-precision machining and manufacturing technology has an increasing demand on high-grade multi-axis numerical control machine tools with ultrahigh-precision rotating shafts, and particularly in the field of manufacturing large-caliber optical free-form surface elements such as inertial confinement nuclear fusion, earth observation, laser radar and EUV lithography. The geometric accuracy of the rotating shaft directly influences key optical performance indexes such as the axis position, the surface shape accuracy, the surface roughness and the like of the large-scale optical lens to be processed, and in addition, the requirements on the geometric accuracy and the performance of the rotating shaft of the numerical control machine tool for off-axis processing of the large-caliber optical element are more strict.
The conventional method for measuring the geometrical error of the rotating shaft mainly comprises a laser interferometer and a ball rod instrument. Most of laser interferometers are used for measuring the positioning error of the rotary table, and the light path is difficult to adjust in the measuring process, so that the laser interferometers are extremely dependent on the level of an operator, and the measuring efficiency is low; the ball arm instrument method can realize the separation of geometric errors only by carrying out multiple times of installation, and the eccentricity needs to be adjusted in the testing process, so that the adjustment is time-consuming, the testing range is smaller, and the measuring precision is lower. The traditional measuring method is limited by the installation position, and cannot measure and distinguish the geometric error of a rotating shaft of any type of machine tool (such as a five-axis numerical control machine tool with an AB swing shaft).
Disclosure of Invention
The invention aims to solve the technical problems that in order to overcome the defects in the prior art, the invention provides a method and a system for identifying the geometric error of a swing head of a five-axis numerical control machine tool, which are used for solving the technical problems that the measurement efficiency of a rotating shaft of the five-axis machine tool is low, the measurement precision is low, and the installation of a measuring instrument is limited by the working space of the machine tool.
The invention adopts the following technical scheme:
a method for identifying a geometrical error of a swing head of a five-axis numerical control machine tool comprises the following steps:
s1, establishing a measurement coordinate system by tracking the position of an interferometer base station by utilizing laser (S) < L X, L Y, L Z) using laser tracking interferometer to track the moving reflecting mirror on the five-axis numerical control machine tool in real time to obtain the machine tool measurementThe distance between the point and the base station and the distance between the measuring points;
s2, calibrating the position of the laser tracking interferometer base station and the three-dimensional coordinate value of the machine tool measuring point under the measuring coordinate system according to the distance obtained in the step S1, determining the measuring coordinate system, and performing homogeneous coordinate transformation with the machine tool coordinate system to obtain a homogeneous transformation matrix between the two coordinate systems
S3, utilizing the homogeneous transformation matrix obtained in the step S2
Will measure the coordinate system ( L X, L Y, L Z) converting the three-dimensional coordinates of the lower measuring point into three-dimensional coordinates under a machine tool coordinate system;
and S4, solving a measuring point space error caused by the geometric error of the machine tool rotating shaft in the machine tool coordinate system obtained in the step S3, determining an identification model of the geometric error related to the position of the rotating shaft, and identifying the swing head geometric error of the five-axis numerical control machine tool by using the identification model.
Specifically, step S1 specifically includes:
s101, placing a laser tracking interferometer on a five-axis numerical control machine tool workbench, and installing a reflector in a tool coordinate system T-CS (T-CS) j J represents the jth initial installation position J =1, … …, J of the reflector, three linear axes of the five-axis numerical control machine tool are moved, and the laser tracking interferometer is respectively positioned in LT of a machine tool working space i The position I represents the position I =1 of the ith base station, … …, I, and the laser tracking interferometer adjusts the yaw angle and the pitch angle of the laser tracking interferometer and tracks the moving reflector in real time;
s102, B-axis rotation angle B k K denotes the K-th measuring point K =1, … …, K, measured by a laser tracking interferometer and records the relative distance change L ijk ；
S103, moving the laser tracking interferometer to the next position LT i+1 Repeating the process of the step S102 until the preset laser tracking interferometer base station positions are all measured;
s104, mounting the reflector to the next initial position t j+1 And the laser tracking interferometer aims again and locks the reflecting mirror, and the steps S102 and S103 are repeated until all the machine tool space measuring points arranged in the experiment are measured.
Specifically, in step S2, the measurement residual u is utilized according to the least square principle ijk And rigid body motion constraint condition residual error r q Solving a least square problem through a condition of minimum sum of squares of residual errors; calculating an optimal solution using Levenberg-Marquardt nonlinear least squares
And determining the space position coordinate of the laser tracking interferometer base station, the actual space three-dimensional coordinate of the measuring point and the dead zone length.
Further, solving the least square function specifically comprises:
k is the number of measuring points in the rotating process of the rotating shaft, V is an unknown vector, F is a least square function, and Q is the number of residual error equations.
Specifically, in step S3, the matrix is transformed in a homogeneous manner
The method specifically comprises the following steps:
wherein, I 3×3 In the form of a third-order identity matrix, M [LT i ]is a theoretical coordinate value of the base station position under the machine tool coordinate system, L [LT i,a ]to measure the actual position of the base station in the coordinate system.
Specifically, step S4 specifically includes:
determining a transformation matrix from a rotating shaft coordinate system to a five-axis numerical control machine tool coordinate system, and establishingA relational expression of the coordinates of the measuring points and the installation position of the reflector; solving the condition that the geometric error of the initial position of the rotating shaft is set to be 0 to obtain the actual initial installation position of the reflector under a B-axis coordinate system B [t j,a ](ii) a And solving the geometric error of the measuring point caused by the geometric error of the rotating shaft under the coordinate system of the five-axis numerical control machine tool, and determining the identification model of the geometric error related to the position of the rotating shaft.
Further, the relation between the coordinate of the measuring point and the installation position of the reflector is specifically as follows:
wherein, M [P jk,n ]under the ideal condition, measuring the coordinates of the points under a coordinate system of the five-axis numerical control machine;
under the ideal condition, a transformation matrix from a B-axis coordinate system to a coordinate system of the five-axis numerical control machine tool is obtained; B [t j,a ]the actual initial installation position of the reflector under a B-axis coordinate system.
Further, solving the geometric error of the measuring point caused by the geometric error of the rotating shaft under the coordinate system of the five-axis numerical control machine tool is specifically as follows:
wherein, M [ΔP jk,GE ]the method is characterized in that the spatial position deviation of a measuring point caused by the geometric error of a B axis is obtained under a machine tool coordinate system; M [P jk,a ]the method comprises the following steps of (1) measuring an actual space three-dimensional coordinate of a point under a machine tool coordinate system; M [P jk,n ]under the ideal condition, measuring the coordinates of the points under a coordinate system of the five-axis numerical control machine;
under the ideal condition, a transformation matrix from a B-axis coordinate system to a coordinate system of a five-axis numerical control machine tool; B [t j,a ]as a B-axis coordinate systemNext, the actual mounting position coordinates of the mirror.
Further, the identification model of the geometric error related to the position of the rotating shaft is specifically as follows:
wherein, M [ΔP jk,PDGE ]is a position-related geometric error matrix generated by the machine tool in the measurement process under the coordinate system of the machine tool, B jk,PDGE As a matrix of coefficients relating to the initial mounting position of the mirror and the angle of rotation of the B axis, E AB (b k ) For the angle error of the B-axis around the X-axis when the axis of rotation is rotated to the kth position, E BB (b k ) For the positioning error of the B-axis when the rotation axis is rotated to the k-th position, E CB (b k ) For the angle error of the B-axis around the Z-axis when the axis is rotated to the k-th position, E XB (b k ) For the straightness error of the B axis in the X axis direction when the rotation axis is rotated to the k-th position, E YB (b k ) Error of straightness of B axis in Y axis direction when the rotation axis is rotated to k position, E ZB (b k ) When the rotating shaft rotates to the k-th position, the straightness error of the B-axis in the Z-axis direction is realized.
In a second aspect, an embodiment of the present invention provides a system for identifying a geometric error of a swing head of a five-axis numerical control machine, where the system includes:
a measurement module for establishing a measurement coordinate system by tracking the position of the interferometer base station with laser light ( L X, L Y, L Z), tracking a moving reflector on a five-axis numerical control machine tool in real time by using a laser tracking interferometer to obtain the distance between a machine tool measuring point and a base station and the distance between each measuring point;
a calibration module for calibrating the laser tracking interferometer base station position and the three-dimensional coordinate value of the machine tool measuring point under the measuring coordinate system according to the distance obtained by the measuring module, determining the measuring coordinate system, and performing homogeneous coordinate transformation with the machine tool coordinate system to obtain a homogeneous transformation matrix between the two coordinate systems
Conversion module, homogeneous transformation matrix obtained by using calibration module
Will measure the coordinate system ( L X, L Y, L Z) converting the three-dimensional coordinates of the lower measuring point into three-dimensional coordinates under a machine tool coordinate system;
and the identification module is used for solving a measuring point space error caused by the geometric error of the machine tool rotating shaft under the machine tool coordinate system obtained by the conversion module, determining an identification model of the geometric error related to the position of the rotating shaft, and identifying the swing head geometric error of the five-axis numerical control machine tool by using the identification model.
Compared with the prior art, the invention has at least the following beneficial effects:
according to the method for identifying the swing geometric error of the five-axis numerical control machine tool, the base station is only installed once, and the position change of the base station is realized through the movement of the workbench, so that the time spent on multiple installation of the base station is reduced, and the measurement efficiency is greatly improved; the rigid body rotation motion constraint theory is introduced, and the random error of measurement is greatly reduced.
Furthermore, the laser tracker is used for measuring the geometric error of the yaw axis, length data are used, and angle data are not needed, so that the measurement precision is improved; the laser tracker four-base-station measurement establishes a measurement coordinate system independent of a machine tool coordinate system, and measurement point space coordinate information does not need to be converted during collection, so that the measurement efficiency is improved.
Furthermore, a rigid body rotation constraint theory is introduced, and the base station position and the measuring point space coordinate are solved by utilizing the least square principle, so that a conversion matrix of a measuring coordinate system and a machine tool coordinate system is determined; the matlab program can be used for realizing the rapid conversion of the coordinates of the measuring points, and a foundation is laid for the next error identification.
Furthermore, according to the rigid body rotation constraint theory, two reflectors which are fixed on the rotating shaft and have different positions rotate at any angle, and the distance between the two reflectors is unchanged; the minimum distance between the measuring points is solved by utilizing the least square principle, so that the position of the base station and the space coordinates of the measuring points are determined, and the uncertainty of measurement caused by random errors is reduced.
Furthermore, the transformation matrix between the two coordinate systems can be directly obtained according to the homogeneous coordinate transformation principle, but the solving is greatly influenced by random errors, and the more accurate coordinate transformation matrix can be determined by determining the coordinate transformation matrix by utilizing the least square method principle.
Further, the actual space error of the measuring points is used for separating and solving the geometric error irrelevant to the position of the rotating shaft, and the actual space error of the measuring points is differed from the space error caused by the error irrelevant to the position of the rotating shaft theoretically, so that the space position error caused by the error relevant to the position of the rotating shaft is obtained, and the error relevant to the position of the rotating shaft is further solved; the separation and identification of the geometric errors of the rotating shaft are realized.
Furthermore, three different positions of the reflector are utilized, and measuring point coordinates corresponding to the positions of the reflector can form multiple groups of equations according to a constraint theory during rigid body rotation, so that a statically indeterminate equation is formed, and the precise solution of the coordinates of the base station is facilitated.
Furthermore, measuring point errors caused by geometric errors of the rotating shaft under the machine tool coordinate system are solved, the evaluation of the change situation of the machine tool space precision under the influence of the geometric errors is facilitated, and the geometric errors of the machine tool can be separated through an error identification model established through the change of theoretical coordinates.
Furthermore, a separation algorithm of the geometric errors related to the position of the rotating shaft is encapsulated into an identification model by utilizing matlab, so that the data processing efficiency can be improved, and the measurement cost is saved; the separation and identification of the machine tool position related error can be realized only by introducing the space error vector caused by the position related error in the measured data into the identification model.
It is understood that the beneficial effects of the second aspect can be referred to the related description of the first aspect, and are not described herein again.
In conclusion, the invention utilizes the additional rigid body motion constraint theory to calibrate the base station position, the dead zone length and the measuring point coordinate of the laser tracker, thereby reducing the influence of random errors on the measurement precision and improving the measurement efficiency and the measurement precision.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a schematic diagram of a laser tracking interferometer measurement;
FIG. 2 is a schematic view of a measurement coordinate system formed by the laser tracking interferometer of the present invention;
FIG. 3 is a schematic diagram of the laser tracking interferometer base station and the measurement point position calculation.
Detailed Description
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, 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.
In the description of the present invention, it should be understood that the terms "comprises" and/or "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and including such combinations, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter associated objects are in an "or" relationship.
It should be understood that although the terms first, second, third, etc. may be used to describe preset ranges, etc. in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, the first preset range may also be referred to as a second preset range, and similarly, the second preset range may also be referred to as the first preset range, without departing from the scope of the embodiments of the present invention.
The word "if," as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection," depending on context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
Various structural schematics according to the disclosed embodiments of the invention are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.
The invention provides a method for identifying a swing geometric error of a five-axis numerical control machine tool, which utilizes four-base-station laser tracking interferometer to perform time-sharing measurement, thereby reducing the measurement cost while ensuring the measurement precision; and a rotational rigid body motion constraint is introduced into a measurement algorithm, so that the measurement uncertainty is effectively reduced. Meanwhile, the self-calibration coordinate system of the four-base-station laser tracking interferometer is used for measurement, so that the limitation of the coordinate system of the numerical control machine tool is eliminated, and the application range is wider. In addition, the invention has the advantages of less detection time, high detection precision and low detection uncertainty, the detection precision meets the detection requirement of the precision numerical control machine tool, and the invention can be used for the error detection of the rotating shaft of the precision numerical control machine tool.
The invention discloses a method for identifying geometric errors of a swing head of a five-axis numerical control machine tool, which comprises a measurement scheme and measurement data processing, and specifically comprises the following steps:
s1, measuring
Referring to fig. 2, during measurement, a measurement coordinate system is established by tracking the position of the interferometer base station with laser. Before measuring the geometric error of a rotating shaft of the five-axis machine tool, the geometric error of a linear shaft needs to be measured firstly, and the accuracy of the linear shaft is ensured to be within a required range; thereby ensuring the measurement accuracy of the geometric error term of the rotating shaft.
Referring to fig. 1, the measurement process is as follows:
s101, placing a single laser tracking interferometer on a workbench of a five-axis numerical control machine tool, and installing a reflector at a position close to the end face of a main shaft, namely T in a tool coordinate system T-CS j (J represents the jth initial mounting position of the mirror J =1, … …, J), and LT for moving three linear axes of the machine tool so that the laser tracking interferometer is located in the working space of the machine tool i In the position (I represents the position I =1 of the ith base station, … …, I), the laser tracking interferometer adjusts the yaw angle and the pitch angle of the laser tracking interferometer and tracks the moving reflector in real time;
s102, B-axis rotation angle B k (K denotes the K-th station K =1, … …, K), the laser tracking interferometer measures and records the relative distance variation L ijk (indicating the base station at the ith position, the jth initial installation position of the mirror, and the B-axis angle B k The relative distance between the measurement point and the base station);
and when the B shaft rotates for one angle, the machine tool stops for a certain time, and the laser tracking interferometer measures and records the relative distance variation once.
S103, moving the laser tracking interferometer to the next position LT i+1 Repeating the process of the step S102 until all the preset base station positions are measured;
S104mounting the reflector to the next initial position t j+1 And (5) the laser tracking interferometer aims again and locks the reflector, and the steps S102 and S103 are repeated until all the measuring points are measured.
Establishing a measurement coordinate system by using the mutual position relationship among four measurement base stations ( L X, L Y, L Z); base station LT 1 The reference point is set as the origin of coordinates, the base station LT 1 Reference point and base station LT 2 With reference points connected by lines arranged to measure the coordinate system L X-axis, measuring coordinate system L Y axis perpendicular to L X-axis, and base station LT 3 Is located at L X L In the Y plane, the measurement coordinate system can be determined according to the right-hand rule of the spiral L The Z axis. The constructed measurement coordinate system constrains six system parameters. Under the measurement coordinate system, the position coordinate of the base station and the three-dimensional coordinate of the actual space of the measuring point have determination solutions.
Setting the position coordinates of four base stations according to the above conditions L [LT i ]Comprises the following steps:
under the measurement coordinate system, the position coordinates of the base station and the three-dimensional coordinate values of the actual space of the measurement point are expressed as L [LT i,a ]And
represents the initial installation position of the jth reflector and the rotation angle of the rotating shaft is b k The coordinate value of the measuring point.
S2, calibrating three-dimensional coordinate values of base station position and measuring point of tracking interferometer
According to the ranging principle of the laser tracking interferometer and the definition of the dead zone length, a nonlinear equation set of the three-dimensional coordinate values of the base station position and the actual space of the measuring point is listed, as shown in a formula (2). Aiming at different two points under the same coordinate system, when the two points move around the same rotating shaft by the same angle, the distance between the two points is kept unchanged; and introducing rigid motion constraint conditions when the reflector rotates around the rotating shaft, as shown in formula (4).
|| L [LT i,a ]- L [P jk,a ]||＝L ijk +l j (2)
Wherein L is ijk The base station is at the ith position, the jth initial installation position of the reflector and the rotating shaft angle b k The relative distance between the point and the base station.
According to the least-squares principle and using the measurement residual u ijk And rigid body motion constraint condition residual error r q Solving the least square problem by the condition of minimum sum of squared residuals, as shown in formula (5); solving the optimal solution by utilizing Levenberg-Marquardt nonlinear least square method
Thereby determining the space position coordinate of the base station, the actual space three-dimensional coordinate of the measuring point and the dead zone length.
Wherein K is the number of measuring points in the rotation process of the rotating shaft, and V is an unknown vector: ( L [LT a ], T [P a ],l) T And respectively representing unknown vectors of a base station position coordinate, a measured point actual space three-dimensional coordinate and a dead zone length in a measured coordinate system, wherein F is a least square function, and Q is the number of residual error equations.
S3, conversion of measurement coordinate system and machine tool coordinate system
The conversion of the measuring coordinate system and the machine tool coordinate system is realized by utilizing the corresponding homogeneous transformation matrix, and the conversion relation of the laser tracking interferometer base station position and the measuring point space coordinate in the two coordinate systems is shown in formulas (6) and (7).
Wherein, M [P jk ,a]is an actual space three-dimensional coordinate value of a measuring point under a coordinate system of a five-axis numerical control machine tool,
is a homogeneous coordinate transformation matrix from a measurement coordinate system to a coordinate system of a five-axis numerical control machine tool.
Wherein, M [LT i ]obtaining a theoretical coordinate value of the base station position from a numerical control system under a machine tool coordinate system; M [LT i,a ]to measure the actual coordinates of the base station position in the coordinate system.
Rewriting to a formula for solving a least squares function according to formula (6), as shown in formula (8); determining a homogeneous coordinate transformation matrix from the measurement coordinate system to the machine coordinate system by solving the least squares function
S4, solving a measuring point space error caused by a machine tool rotating shaft (swing head) geometric error under a machine tool coordinate system;
determining a conversion matrix from a rotating shaft coordinate system to a machine tool coordinate system according to a topological structure of a five-axis machine tool; thereby establishing a relational expression of the coordinates of the measuring points and the installation position of the reflecting mirror, which is shown in a formula (9). Solving the condition that the geometric error of the initial position of the rotating shaft is set to be 0 to obtain the actual initial installation position of the reflector under a B-axis coordinate system B [t j,a ](ii) a And solving the geometric error of the measuring point caused by the geometric error of the rotating shaft under the machine tool coordinate system according to the formula (10).
Wherein, M [P jk,n ]under the ideal condition, measuring the coordinates of the point under a machine tool coordinate system;
under the ideal condition, a transformation matrix from a B-axis coordinate system to a machine tool coordinate system; B [t j,a ]the actual initial installation position of the reflector under a B-axis coordinate system.
Wherein, M [ΔP jk,GE ]the method is characterized in that the method is a measuring point space position deviation caused by a B-axis geometric error under a machine tool coordinate system; M [P jk,a ]the method comprises the following steps of (1) measuring an actual space three-dimensional coordinate of a point under a machine tool coordinate system; M [P jk,n ]under the ideal condition, measuring the coordinates of the point under a machine tool coordinate system;
under the ideal conditionA transformation matrix from the B axis coordinate system to the machine tool coordinate system; B [t j,a ]and the actual installation position coordinates of the reflector under the B-axis coordinate system.
According to the spatial position error caused by the geometric error of the rotating shaft obtained above, the geometric error of the rotating shaft is separately identified through step S401 and step S402, which is as follows:
separation and identification of geometric errors of rotating shaft (swing head)
S401, separating and identifying position-independent errors of rotating shaft (swing head)
Forming a mode group by all the measuring point models, namely a formula (11); to be solved M [ΔP jk,GE ]Instead of the former M [ΔP jk,PIGE ]The formula (11) is solved by using the least square principle, thereby separating 4-term PIGEs (E) of the rotation axis AOB ,E COB ,E XOB ,E ZOB )。
Substituting 4 PIGEs of the rotation axis into formula (11), and solving the position-independent geometric error caused by the geometric error of the rotation axis M [ΔP PIGE ]。
Wherein, M [ΔP PIGE ]a spatial error matrix caused by position-independent errors at all measuring points under a machine tool coordinate system; b is PIGE Is a matrix of coefficients relating to the initial mirror mounting position and the B-axis rotation angle at all measurement points.
S402, separating and identifying the position related error of a rotating shaft (swing head);
according to the machine tool coordinate conversion matrix and the machine tool rotating shaft position correlation errorDefining difference, determining an identification model of geometric errors related to the head swing position as shown in a formula (14), substituting a formula (15) into the formula (14), and solving by using a least square method to obtain PDGEs (E) with 6 terms of rotating shafts AB (b k ),E BB (b k ),E CB (b k ),E XB (b k ),E YB (b k )，E ZB (b k ))。
M [ΔP GE-PIGE ]＝ M [ΔP GE ]- M [ΔP PIGE ] (15)
Wherein, B jk,PDGE Is a matrix of coefficients related to the initial mounting position of the mirror and the rotation angle of the B-axis.
In another embodiment of the present invention, a system for identifying a geometric error of a wobble head of a five-axis numerical control machine is provided, where the system can be used to implement the method for identifying a geometric error of a wobble head of a five-axis numerical control machine.
Wherein, the measuring module uses the laser to track the position of the interferometer base station to establish a measuring coordinate system ( L X, L Y, L Z), tracking a moving reflector on a five-axis numerical control machine tool in real time by using a laser tracking interferometer to obtain the distance between a machine tool measuring point and a base station and the distance between each measuring point;
a calibration module for calibrating the laser tracking interferometer base station position and the three-dimensional coordinate value of the machine tool measuring point under the measuring coordinate system according to the distance obtained by the measuring module, determining the measuring coordinate system, and performing homogeneous coordinate transformation with the machine tool coordinate system to obtain a homogeneous transformation matrix between the two coordinate systems
Conversion module, homogeneous transformation matrix obtained by using calibration module
Will measure the coordinate system ( L X, L Y, L Z) converting the three-dimensional coordinates of the lower measuring point into three-dimensional coordinates under a machine tool coordinate system;
and the identification module is used for solving a measuring point space error caused by the geometric error of the machine tool rotating shaft under the machine tool coordinate system obtained by the conversion module, determining an identification model of the geometric error related to the position of the rotating shaft, and identifying the swing head geometric error of the five-axis numerical control machine tool by using the identification model.
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. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the 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.
Examples
Referring to fig. 3, in the embodiment, four base stations are used to measure the geometric error of the rotating shaft in a time-sharing manner; when each base station is used for measurement, three reflectors at different positions are sequentially arranged according to the positions to measure the geometric errors of the rotating shaft; and calibrating a measurement coordinate system by using a rotation rigid body constraint theory.
The measurement takes 100min, 4 PIGEs and 6 PDGEs of different rotating shafts of the five-axis numerical control machine tool can be obtained by substituting the test data into a calculation program compiled by MTALAB, 20 rotating shaft geometric errors are obtained, the detection efficiency is extremely high, the measurement efficiency of the geometric errors of the numerical control rotary table is greatly improved on the premise of ensuring the measurement accuracy, and the five-axis numerical control machine tool rotating shaft geometric error detection has wide engineering application prospect and practical application value.
In conclusion, the method and the system for identifying the swing geometric error of the five-axis numerical control machine tool greatly improve the measurement efficiency and the measurement precision, can reduce the overhaul cost of the machine tool in engineering application, improve the use efficiency of the machine tool and reduce the production cost.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. A method for identifying a swing head geometric error of a five-axis numerical control machine tool is characterized by comprising the following steps:
s1, establishing a measurement coordinate system by tracking the position of an interferometer base station by utilizing laser (S) < L X, L Y, L Z), tracking a moving reflector on a five-axis numerical control machine tool in real time by using a laser tracking interferometer to obtain the distance between a machine tool measuring point and a base station and the distance between each measuring point;
s2, calibrating the position of the laser tracking interferometer base station and the three-dimensional coordinate value of the machine tool measuring point under the measuring coordinate system according to the distance obtained in the step S1, determining the measuring coordinate system, and performing homogeneous coordinate transformation with the machine tool coordinate system to obtain a homogeneous transformation matrix between the two coordinate systems
S3, utilizing the homogeneous transformation matrix obtained in the step S2
Will measure the coordinate system ( L X, L Y, L Z) converting the three-dimensional coordinates of the lower measuring point into three-dimensional coordinates under a machine tool coordinate system;
and S4, solving a measuring point space error caused by the geometric error of the machine tool rotating shaft in the machine tool coordinate system obtained in the step S3, determining an identification model of the geometric error related to the position of the rotating shaft, and identifying the swing head geometric error of the five-axis numerical control machine tool by using the identification model.
2. The method for identifying the swing head geometric error of the five-axis numerical control machine tool according to claim 1, wherein the step S1 is specifically as follows:
s101, placing a laser tracking interferometer on a five-axis numerical control machine tool workbench, and installing a reflector in a tool coordinate system T-CS (T-CS) j J represents the jth initial installation position J =1, … …, J of the reflector, three linear axes of the five-axis numerical control machine tool are moved, and the laser tracking interferometers are respectively positioned in LT of a machine tool working space i The position I represents the position I =1 of the ith base station, … …, I, and the laser tracking interferometer adjusts the yaw angle and the pitch angle of the laser tracking interferometer and tracks the moving reflector in real time;
s102, B-axis rotation angle B k K denotes the K-th measuring point K =1, … …, K, and the laser tracking interferometer measures and records the relative distance change L ijk ；
S103, moving the laser tracking interferometer to the next position LT i+1 Repeating the process of the step S102 until the preset laser tracking interferometer base station positions are all measured;
s104, mounting the reflector to the next initial position t j+1 And the laser tracking interferometer aims again and locks the reflecting mirror, and the steps S102 and S103 are repeated until all the machine tool space measuring points arranged in the experiment are measured.
3. The method for identifying yaw geometry error of five-axis numerical control machine tool according to claim 1, wherein in step S2, the measurement residual u is utilized according to the principle of least squares ijk And rigid body motion constraint condition residual error r q Solving a least square problem through a condition of minimum sum of squares of residual errors; calculating the optimal solution by using Levenberg-Marquardt nonlinear least square method
Determining laser lightAnd tracking the space position coordinates of the interferometer base station, the actual space three-dimensional coordinates of the measuring points and the dead zone length.
4. The method for identifying the yaw geometry error of the five-axis numerical control machine according to claim 3, wherein solving the least square function specifically comprises:
k is the number of measuring points in the rotating process of the rotating shaft, V is an unknown vector, F is a least square function, and Q is the number of residual error equations.
5. The method for identifying yaw geometry error of five-axis numerical control machine tool according to claim 1, wherein in step S3, the homogeneous transformation matrix is used
The method specifically comprises the following steps:
wherein, I 3×3 In the form of a third-order identity matrix, M [LT i ]is a theoretical coordinate value of the base station position under the machine tool coordinate system, L [LT i,a ]to measure the actual position of the base station in the coordinate system.
6. The method for identifying the geometric error of the yaw of the five-axis numerical control machine according to claim 1, wherein the step S4 specifically comprises:
determining a conversion matrix from a rotating shaft coordinate system to a five-axis numerical control machine tool coordinate system, and establishing a relational expression of measuring point coordinates and a reflector mounting position; solving the condition that the geometric error of the initial position of the rotating shaft is set to be 0 to obtain the actual initial installation position of the reflector under a B-axis coordinate system B [t j,a ](ii) a Solution five-axis numerical control machine tool seatAnd determining an identification model of the geometric error related to the position of the rotating shaft by measuring point geometric errors caused by the geometric errors of the rotating shaft under the standard system.
7. The method for identifying the geometric error of the yaw of the five-axis numerical control machine tool according to claim 6, wherein the relational expression between the coordinates of the measuring point and the mounting position of the reflecting mirror is as follows:
wherein, M [P jk,n ]under the ideal condition, measuring the coordinates of the points under a coordinate system of the five-axis numerical control machine;
under the ideal condition, a transformation matrix from a B-axis coordinate system to a coordinate system of a five-axis numerical control machine tool; B [t j,a ]the actual initial installation position of the reflector under a B-axis coordinate system.
8. The method for identifying the geometric error of the yaw of the five-axis numerical control machine tool according to claim 6, wherein solving the geometric error of the measuring point caused by the geometric error of the rotating shaft under the coordinate system of the five-axis numerical control machine tool is specifically as follows:
wherein, M [ΔP jk,GE ]the method is characterized in that the spatial position deviation of a measuring point caused by the geometric error of a B axis is obtained under a machine tool coordinate system; M [P jk,a ]the method comprises the following steps of (1) measuring an actual space three-dimensional coordinate of a point under a machine tool coordinate system; M [P jk,n ]under the ideal condition, measuring the coordinate of a point under a coordinate system of the five-axis numerical control machine;
ideally, from the B-axis coordinateA transformation matrix tied to a coordinate system of the five-axis numerical control machine tool; B [t j,a ]and the actual installation position coordinates of the reflector under the B-axis coordinate system.
9. The method for identifying the yaw geometry error of the five-axis numerical control machine tool according to claim 6, wherein the identification model of the geometric error related to the position of the rotating shaft is specifically as follows:
wherein, M [ΔP jk,PDGE ]is a position-related geometric error matrix generated by the machine tool in the measurement process under the coordinate system of the machine tool, B jk,PDGE As a matrix of coefficients relating to the initial mounting position of the mirror and the angle of rotation of the B axis, E AB (b k ) For the angle error of the B-axis around the X-axis when the axis of rotation is rotated to the kth position, E BB (b k ) For the positioning error of the B-axis when the rotation axis is rotated to the k-th position, E CB (b k ) For the angle error of the B-axis around the Z-axis when the axis is rotated to the k-th position, E XB (b k ) For the straightness error of the B axis in the X axis direction when the rotation axis is rotated to the k-th position, E YB (b k ) For the straightness error of the B axis in the Y axis direction when the rotation axis is rotated to the k-th position, E ZB (b k ) When the rotating shaft rotates to the k-th position, the straightness error of the B-axis in the Z-axis direction is realized.
10. The utility model provides a five digit control machine tool pendulum head geometric error identification system which characterized in that includes:
a measurement module for establishing a measurement coordinate system by tracking the position of the interferometer base station with laser light ( L X, L Y, L Z), tracking a moving reflector on a five-axis numerical control machine tool in real time by using a laser tracking interferometer to obtain the distance between a machine tool measuring point and a base station and the distance between each measuring point;
a calibration module for calibrating the laser tracking rod according to the distance obtained by the measurement moduleThe position of the interferometer base station and the three-dimensional coordinate value of the machine tool measuring point in the measuring coordinate system are determined, the measuring coordinate system is determined, homogeneous coordinate transformation is carried out on the measuring coordinate system and the machine tool coordinate system, and a homogeneous transformation matrix between the two coordinate systems is obtained
Conversion module, homogeneous transformation matrix obtained by using calibration module
Will measure the coordinate system ( L X, L Y, L Z) converting the three-dimensional coordinates of the lower measuring point into three-dimensional coordinates under a machine tool coordinate system;
and the identification module is used for solving a measuring point space error caused by the geometric error of the machine tool rotating shaft under the machine tool coordinate system obtained by the conversion module, determining an identification model of the geometric error related to the position of the rotating shaft, and identifying the swing head geometric error of the five-axis numerical control machine tool by using the identification model.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211288741.5A CN115415853A (en) | 2022-10-20 | 2022-10-20 | Method and system for identifying geometric error of swing head of five-axis numerical control machine tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211288741.5A CN115415853A (en) | 2022-10-20 | 2022-10-20 | Method and system for identifying geometric error of swing head of five-axis numerical control machine tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115415853A true CN115415853A (en) | 2022-12-02 |
Family
ID=84207860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211288741.5A Pending CN115415853A (en) | 2022-10-20 | 2022-10-20 | Method and system for identifying geometric error of swing head of five-axis numerical control machine tool |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115415853A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116382191A (en) * | 2023-04-07 | 2023-07-04 | 成都飞机工业（集团）有限责任公司 | Numerical control machining method and coordinate system establishment method for finished part based on part characteristics |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107186548A (en) * | 2017-06-08 | 2017-09-22 | 大连理工大学 | A kind of five-axle number control machine tool gyroaxis geometric error detection method |
| CN110524309A (en) * | 2019-08-30 | 2019-12-03 | 西安交通大学 | Numerical control rotating platform geometric error measurement method based on four base station laser traces systems |
| CN112276674A (en) * | 2020-10-13 | 2021-01-29 | 上海交通大学 | Precision measurement method and system for geometric motion error of rotating shaft of multi-axis numerical control machine tool |
| CN112518422A (en) * | 2020-11-19 | 2021-03-19 | 西安交通大学 | Five-axis AC swing head gantry machine tool geometric error modeling and separating method |
| CN113601269A (en) * | 2021-08-26 | 2021-11-05 | 西南交通大学 | Novel method for quickly separating geometric errors of rotating shaft of multi-shaft numerical control machine tool |
| KR20220023271A (en) * | 2020-08-20 | 2022-03-02 | 한국기계연구원 | Method for measuring geometric errors of 5-axis machine tools |
-
2022
- 2022-10-20 CN CN202211288741.5A patent/CN115415853A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107186548A (en) * | 2017-06-08 | 2017-09-22 | 大连理工大学 | A kind of five-axle number control machine tool gyroaxis geometric error detection method |
| CN110524309A (en) * | 2019-08-30 | 2019-12-03 | 西安交通大学 | Numerical control rotating platform geometric error measurement method based on four base station laser traces systems |
| KR20220023271A (en) * | 2020-08-20 | 2022-03-02 | 한국기계연구원 | Method for measuring geometric errors of 5-axis machine tools |
| CN112276674A (en) * | 2020-10-13 | 2021-01-29 | 上海交通大学 | Precision measurement method and system for geometric motion error of rotating shaft of multi-axis numerical control machine tool |
| CN112518422A (en) * | 2020-11-19 | 2021-03-19 | 西安交通大学 | Five-axis AC swing head gantry machine tool geometric error modeling and separating method |
| CN113601269A (en) * | 2021-08-26 | 2021-11-05 | 西南交通大学 | Novel method for quickly separating geometric errors of rotating shaft of multi-shaft numerical control machine tool |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116382191A (en) * | 2023-04-07 | 2023-07-04 | 成都飞机工业（集团）有限责任公司 | Numerical control machining method and coordinate system establishment method for finished part based on part characteristics |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110524309B (en) | Geometric error measuring method of numerical control turntable based on four-base-station laser tracking system | |
| CN104625880B (en) | A kind of five-axis machine tool cutter-orientation and the synchronous testing agency of point of a knife point site error | |
| Deng et al. | Geometric errors identification considering rigid-body motion constraint for rotary axis of multi-axis machine tool using a tracking interferometer | |
| Schwenke et al. | Error mapping of CMMs and machine tools by a single tracking interferometer | |
| CN109732402B (en) | Laser interferometer based multi-line machine tool space geometric error measurement identification method | |
| CN105136031A (en) | Five-axis linkage machine tool rotation shaft geometric error continuous measurement method | |
| CN111678472B (en) | Error identification method for rotary table of four-axis coordinate measuring machine | |
| CN102430959A (en) | Method for rapidly detecting motion error of numerical control machine turntable | |
| CN103389038A (en) | Targeting multi-station measuring method for detecting geometric accuracy of numerical control machine tool through laser tracker | |
| Huang et al. | Identification of geometric errors of rotary axes on 5-axis machine tools by on-machine measurement | |
| CN106363465A (en) | Method for identifying mutual position relationship of horizontally moving shafts and rotating shaft of multi-axis numerically-controlled machine tool | |
| CN204893581U (en) | Continuous measuring device of geometrical error of five -axle linkage lathe rotation axis | |
| CN112325773B (en) | Method for calibrating beam direction vector and origin position of laser displacement sensor | |
| CN106406237B (en) | A kind of processing method with free form surface metal parts | |
| CN110161965B (en) | On-machine measurement method for large-scale aerospace casing inclined hole | |
| CN107091608B (en) | A kind of five degree of freedom measurement method of parameters based on primary standard of curved surface part | |
| Zha et al. | Four-station laser tracer-based geometric error measurement of rotary table | |
| Wang et al. | Research on volumetric error compensation for NC machine tool based on laser tracker measurement | |
| Wang et al. | The identification method of the relative position relationship between the rotary and linear axis of multi-axis numerical control machine tool by laser tracker | |
| CN109884659B (en) | Large-scale precise rotary table calibration method based on laser tracker multi-station measurement system | |
| CN105371793A (en) | One-time clamping measurement method for geometric error of rotating shaft of five-axis machine tool | |
| CN114012585B (en) | Polishing point position calibration method for double-pendulum-shaft type five-axis magnetorheological machine tool | |
| CN115415853A (en) | Method and system for identifying geometric error of swing head of five-axis numerical control machine tool | |
| Xing et al. | Comparison of direct and indirect methods for five-axis machine tools geometric error measurement | |
| Gąska et al. | Simulation model for uncertainty estimation of measurements performed on five-axis measuring systems |
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 |