A hole system workpiece parallelism error measurement method and a measurement device thereof

Abstract

The application discloses a hole series workpiece parallelism error measurement method and a measurement device thereof, which comprises at least five displacement sensors installed on a connecting frame in the same hole, and installation position parameters of the sensors are acquired; the measurement device is calibrated by using a standard workpiece; the measurement device is installed on a workpiece to be measured on a machining machine tool to perform measurement; data processing is performed to establish a space straight line position relationship of displacement sensor readings in the same hole about the connecting frame axis and the hole center line, and a space straight line position relationship of the remaining holes to be measured and the reference hole center line is further established, and parallelism error is calculated; and the position of the measurement device is changed to perform multi-position measurement.

Description

Technical Field

[0001] This invention relates to a method and apparatus for measuring parallelism error, and in particular to a method and apparatus for measuring parallelism error of hole-system workpieces, belonging to the field of parallelism measurement technology. Background Technology

[0002] A hole-system workpiece refers to a workpiece consisting of two or more holes with certain relative positions in space. The parallelism error of this workpiece affects its matching accuracy with other workpieces, thus impacting the overall product quality. Hole machining is a crucial step in the processing of hole-system workpieces, and its quality determines whether the workpiece meets the conditions for further processing. Accurate measurement of the parallelism error of hole-system workpieces allows for the timely detection of problems in the production process, providing guidance for subsequent machining, thereby ensuring product quality, reducing production costs, and improving production efficiency.

[0003] However, measuring the parallelism error of hole-system workpieces presents significant challenges. First, the unique nature of the measurement object makes parallelism error measurement complex and difficult, as hole-system workpieces are typically three-dimensional structures containing multiple holes of different directions and depths. Furthermore, the influence of factors such as hole wall finish, roughness, and foreign matter on the measurement results must be considered. Second, extracting the centerline of a single hole is also challenging, as it requires measuring the inner surface of the workpiece. Single image or laser methods are insufficient; multiple sensors must be used in conjunction to effectively extract the hole centerline. Finally, modeling the spatial relationship between the centerlines of each hole requires characterizing them in the same coordinate system. However, the distance between these spatial lines is significant, making it difficult to guarantee the model's accuracy. Currently, the measurement of parallelism error in hole-system workpieces primarily utilizes coordinate measuring machines (CMMs), which are inefficient, costly, and difficult to perform on-machine measurements. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings of existing technologies, this invention provides a method and device for measuring the parallelism error of a hole system workpiece. This invention transforms the coordinates of the center lines of the remaining holes to be measured into the coordinate system of the center line of the reference hole, thereby unifying the center lines of the remaining holes to be measured and the center line of the reference hole into the same coordinate system, thus completing the parallelism measurement of the hole system workpiece.

[0005] Technical solution: A method for measuring the parallelism error of a hole system workpiece, comprising the following steps:

[0006] S1: After determining the number of displacement sensors to be installed for the reference hole based on the simulation, install the displacement sensors in a circular arrangement on the connecting frame. At the same time, install the displacement sensors required for the other holes to be measured in the same way. The number of displacement sensors required for the other holes to be measured is the same as that for the reference hole. The measuring device is now installed.

[0007] S2: Determine the installation angle θ and installation height h of the displacement sensors for each hole on the connecting frame, and establish a spatial rectangular coordinate system σ on the axis perpendicular to the connecting frame for each hole. k ;

[0008] S3: Use the installed measuring device to measure a standard workpiece with known parallelism, compare the measured value with the standard value, calibrate the measuring device, and then measure the workpiece to be measured.

[0009] S4: Determine the coordinates of the centerline l1 of the datum hole in the datum hole connecting frame coordinate system σ1;

[0010] S5: Determine the centerline of the remaining holes to be tested. k In the coordinate system σ of the remaining holes to be measured k Coordinates in;

[0011] S6: For the coordinate system σ of the remaining holes to be measured, k Unify the coordinate system σ1 with the reference hole connecting frame;

[0012] S7: Establish the coordinate system σ′ of the reference hole centerline l1, and determine the centerlines l of the remaining holes to be measured. k The coordinates in the coordinate system σ′ of the reference hole centerline l1;

[0013] S8: Determine l1 and l k Spatial linear positional relationship ζ 1-k And calculate the parallelism;

[0014] S9: Change the position of the measuring device relative to the workpiece being measured, return to S4, and perform parallelism measurements at different positions.

[0015] This invention first unifies the centerline coordinates of each hole into its respective connecting frame coordinate system. Then, it unifies the connecting frame coordinate systems of the remaining holes to be tested with the coordinate system of the reference hole connecting frame. A reference hole centerline coordinate system is established with the centerline of the reference hole as the reference line. The centerline coordinates of the remaining holes to be tested are then unified into the reference hole centerline coordinate system. This ensures that the centerline of the reference hole and the centerlines of the remaining holes to be tested are in the same coordinate system. The spatial linear position relationship is then determined based on this, and the parallelism is obtained. After comparison with the standard, the parallelism error is obtained, providing evidence for the correction of the machine tool.

[0016] In the preferred embodiment, the specific steps of S1 are as follows:

[0017] Let L be a straight line in three-dimensional space, and l be the center line of the hole near the straight line L. Establish a spatial rectangular coordinate system σ = [O; X, Y, Z] on the straight line L, so that the Z axis coincides with L. Then, transform L by rotating it around the X axis by an angle α, moving it along the X axis by a distance e, rotating it around the Z axis by an angle β, and moving it along the Z axis by a distance d.

[0018] The positional relationship between two spatial lines L and l is uniquely represented by ζ:

[0019] ζ=(α,e,β,d)(1)

[0020] Where α is the rotation angle of L around the X-axis; e is the distance L moves along the X-axis; β is the rotation angle of L around the Z-axis; and d is the distance L moves along the Z-axis.

[0021] Make the initial position of l coincide with L, and make the target position of l the final position. During the transformation from the initial position to the final position, the pose change of the cylindrical surface of the hole is consistent with the center line l of the hole.

[0022] Let P be the coordinates of a point on the cylindrical surface of the hole. i (x i y i , z i ), (i = 1, 2, 3…), according to formula (1), establish P i The relationship with ζ:

[0023] (x i cosβ-e+y i sinβ) 2 +[(z i -h)sinα+y i cosαcosβ-x i cosαsinβ] 2 =r 2 (2)

[0024] Where r represents the radius of the hole;

[0025] Let point P be on the cylindrical surface of the hole. i The function is gf i :

[0026] gf i =(x i cosβ-e+y i sinβ) 2 +[(z i -h)sinα+y i cosαcosβ-x i cosαsinβ] 2 -r 2 (3)

[0027] Let the objective function be F:

[0028]

[0029] The minimum value of the objective function is obtained by using an optimization function. The simulation results show that the unique solution of ζ can only be obtained when i≥5. Therefore, the reference hole requires at least five displacement sensors, and the number of displacement sensors required for the other holes to be measured is the same as that for the reference hole.

[0030] In the preferred embodiment, the specific steps of S2 are as follows:

[0031] Let the axis of the connecting bracket for mounting the reference hole be L1, and let axis L1 be perpendicular to the connecting bracket. Let the centerline of the reference hole be l1. Let the axis of the connecting bracket for mounting the other holes to be measured be L. k (k = 2, 3, 4, ...), axis L k Perpendicular to the connecting frame, the centerline of the remaining holes to be measured is l. k ;

[0032] Establish a spatial rectangular coordinate system σ1 = [O1; X1, Y1, Z1] on axis L1, with the Z1 axis coinciding with L1. Five displacement sensors are defined by E. i (i = 1, 2, 3, 4, 5), installation angle is θ i The installation height is h i ; on axis L k Establish a spatial rectangular coordinate system σ on the above k =[O k ;X k Y k Z k ], making Z k Axis and L k Overlapping, five displacement sensors for E j (j=1, 2, 3, 4, 5), installation angle is θ j The installation height is h j .

[0033] In a preferred embodiment, the specific steps of S4 are as follows:

[0034] S401: Determine the positional relationship ζ1 between the connecting bracket axis L1 of the reference hole and the center line l1 of the reference hole;

[0035] L1 is rotated by an angle α1 around the X1 axis, moved by a distance e1 along the X1 axis, rotated by an angle β1 around the Z1 axis, and moved by a distance d1 along the Z1 axis before being transformed into L1.

[0036] The positional relationship between two spatial lines L1 and l1 is uniquely represented by ζ1:

[0037] ζ1=(α1, e1, β1, d1) (5)

[0038] Where α1 is the rotation angle of L1 around the X1 axis, e1 is the distance L1 moves along the X1 axis, β1 is the rotation angle of L1 around the Z1 axis, and d1 is the distance L1 moves along the Z1 axis.

[0039] S402: Based on ζ1 in S401, the coordinates of the centerline l1 of the reference hole in the reference hole connecting frame coordinate system σ1 are obtained by transformation matrix;

[0040] Make the initial position of l1 coincide with L1, and make the target position of l1 the final position. During the process of changing from the initial position to the final position, the pose change of the reference hole cylindrical surface is consistent with the center line l1 of the reference hole.

[0041] According to formula (5), the sensor reading S is established. i The relationship with ζ1:

[0042]

[0043] Among them, S i D represents the reading of the i-th displacement sensor measuring the reference hole. i θ represents the distance from the zero point of the displacement sensor probe to the Z1 axis. i h represents the installation angle of the displacement sensor. i The value r represents the installation height of the displacement sensor, and r1 represents the radius of the reference hole.

[0044] Let the displacement sensor reading S be... i The function is f i :

[0045]

[0046] Let the objective function be F1:

[0047]

[0048] Where f1 is a function of displacement sensor reading S1, f2 is a function of displacement sensor reading S2, f3 is a function of displacement sensor reading S3, f4 is a function of displacement sensor reading S4, and f5 is a function of displacement sensor reading S5.

[0049] ζ1 can be obtained by finding the minimum value of the objective function using the optimization function;

[0050] The formulas for the rotation and translation matrices Rot(x, α), Rot(z, β), Trans(e 0 0), and Trans(0 0 d) are as follows:

[0051]

[0052] The coordinate transformation matrix from L1 to l1 is denoted as T1:

[0053] T1=Trans(0 0 d1)Rot(Z1,β1)Trans(e1 0 0)Rot(X1,α1) (10)

[0054] Let the coordinates of a point on the Z1 axis in σ1 be (0, 0, qz), and the coordinates of a point on the l1 axis in σ1 be (x, y, qz). p1 y p1 , z p1 ),but:

[0055]

[0056] That is, the coordinates of the center line l1 of the reference hole in the coordinate system σ1 of the reference hole connecting frame are obtained.

[0057] In a preferred embodiment, the specific steps of S5 are as follows:

[0058] S501: Determine the axis L of the connecting bracket for the remaining holes to be tested. k and the center line of the other holes to be tested l k Positional relationship ζ k ;

[0059] L k Circling X in sequence k Axis rotation angle α k Along X k Axis travel distance e k , around Z k Axis rotation angle β k Along Z k Axis movement distance d k After transformation to l k ;

[0060] Two spatial lines L k With l k Positional relationships are represented by ζ k Unique representation:

[0061] ζ k =(α k e k ,β k d k (12)

[0062] Where, α k For L k Around X k Axis rotation angle, e k For L k Along X kAxis travel distance, β k For L k Around Z k Axis rotation angle, d k For L k Along Z k Axis travel distance;

[0063] S502: According to ζ in S501 k The centerline l of the remaining holes to be tested is obtained by transforming the matrix. k In the coordinate system σ of the remaining holes to be measured k Coordinates in;

[0064] Make l k The initial position and L k Overlap, making l k The target position is the final position. During the transformation from the initial position to the final position, the pose change of the cylindrical surface of the hole is consistent with the center line of the hole.

[0065] According to formula (12), the sensor reading S is established. j With ζ k Relationship:

[0066]

[0067] Among them, S j D represents the reading of the j-th sensor used to measure the remaining holes to be measured. j Indicates the zero position to Z position of the displacement sensor probe. k Distance between axes, θ j h represents the installation angle of the displacement sensor. j The value r represents the installation height of the displacement sensor. k This represents the radius of the remaining test holes k;

[0068] Let the displacement sensor reading S be... j The function is g j :

[0069]

[0070] Let the objective function F k :

[0071]

[0072] Where g1 is a function of displacement sensor reading S1, g2 is a function of displacement sensor reading S2, g3 is a function of displacement sensor reading S3, g4 is a function of displacement sensor reading S4, and g5 is a function of displacement sensor reading S5.

[0073] By finding the minimum value of the objective function using the optimization function, ζ can be obtained. k ;

[0074] From L k Transform to l k The coordinate transformation matrix is ​​denoted as T. k :

[0075] T k =Trans(0 0 d) k Rot(Z) k ,β k Trans(e) k 0 0)Rot(X k α k (16)

[0076] Let Z k Points on the axis at σ k The coordinates in the equation are (0, 0, qz). k ), l k The point on σ k The coordinates in (x) pk y pk , z pk ),but:

[0077]

[0078] That is, the center line l of the remaining holes to be measured is obtained. k In the coordinate system σ of the remaining holes to be measured k The coordinates in the diagram.

[0079] In a preferred embodiment, the specific steps of S6 are as follows:

[0080] From coordinate system σ k The matrix transformed to σ1 is denoted as M. 1k Let σ k The coordinates of the origin in σ1 are (x ok y ok , z ok ), then σ k →σ1:

[0081]

[0082] Let l k The coordinates of the point on the x-axis in σ1 are (x-y) pk1 y pk1 , z pk1 According to formula (17), then:

[0083]

[0084] That is, to complete the coordinate system σ of the remaining test holes connecting frame k The coordinate system σ1 of the reference hole connecting frame is unified.

[0085] In the preferred embodiment, the specific steps of S7 are as follows:

[0086] Establish a spatial rectangular coordinate system σ′ = [O′; X′, Y′, Z′] on l1; make the Z′ axis coincide with l1; let the coordinates of a point on l1 in σ′ be (x, Y, Z′). p1 ′,y p1 ′,z p1 '),but:

[0087]

[0088] Let l k The coordinates of the point on the x-axis in σ′ are (x-y) pk1 ′,y pk1 ′,z pk1 According to formula (19), then:

[0089]

[0090] That is, the center line l of the remaining holes to be measured is obtained. k The coordinates in the coordinate system σ′ of the center line l1 of the reference hole.

[0091] In the preferred embodiment, the specific steps of S8 are as follows:

[0092] Find l1 and l k Spatial linear positional relationship ζ 1-k :

[0093] ζ 1-k =(α 1-k e 1-k ,β 1-k d 1-k ) (twenty two)

[0094] Using the center line l1 of the reference hole as the reference line, measure the center lines l of the other holes to be measured. k The parallelism relative to l1; then the parallelism magnitude t pa The calculation formula is:

[0095] t pa =Htanω (23)

[0096] Where H is the hole depth; ω is the angle between the two spatial lines; ω = α 1-k ;

[0097] In three-dimensional space, parallelism errors of the same magnitude can have different directions; therefore, a direction angle is introduced. To indicate the direction of parallelism error, i.e.

[0098] Let the measurement result be t. pan , The parallelism is then characterized as follows:

[0099]

[0100] Where t par Indicates the degree of parallelism. Indicates the direction of parallelism.

[0101] A device for measuring the parallelism error of a hole system workpiece includes an adjustable connecting frame and measuring components. At least two sets of mutually parallel measuring components are installed on the adjustable connecting frame. The measuring components are vertically installed on the adjustable connecting frame and include at least five displacement sensor components distributed along the circumferential direction.

[0102] This invention integrates multiple displacement sensors to jointly measure the parallelism of a hole system workpiece. This solves the problem of needing to integrate multiple displacement sensors to measure the parallelism of holes. Furthermore, the invention enables the use of this measuring device to model the spatial positional relationship of the center lines of each hole to be measured, thereby representing the center lines of each hole to be measured in the same coordinate system and finally obtaining the parallelism error. Moreover, the measurement does not require disassembling the workpiece, allowing for direct on-machine measurement, making it more convenient to use. Additionally, multiple sets of data can be obtained by changing multiple positions, resulting in more accurate parallelism measurement results.

[0103] In a preferred embodiment, for ease of measurement, the displacement sensor assembly includes a displacement sensor, a probe, a probe head, and an adjustable mounting base. One end of the probe is connected to the displacement sensor, and the other end is connected to the probe head. The displacement sensor is mounted on the adjustable mounting base, and the probe head contacts the inner wall of the hole. The probe has a Z-shaped structure. Because the displacement sensor is relatively large, a Z-shaped probe head is mounted on it. During measurement, the displacement sensor body does not enter the hole to be measured; only the probe head is inserted into the hole via the probe head, where it contacts the inner wall. Simultaneously, the adjustable mounting base adjusts the distance between each displacement sensor assembly and the adjustable connecting frame, ensuring that the adjustable connecting frame is parallel to the workpiece during measurement. This improves measurement accuracy and solves the problem of excessively large displacement sensors that cannot be installed simultaneously.

[0104] Beneficial effects: This invention determines the spatial linear positional relationship of the reference hole centerline and the centerlines of the other holes to be measured by transforming them into the same coordinate system, thus obtaining the parallelism. After comparing with the standard value, the parallelism error is obtained, reducing the difficulty of parallelism error measurement. Furthermore, by jointly solving multiple displacement sensors, the measurement of the inner surface of the hole system workpiece is completed. By unifying the coordinates of the axes of the other holes to be measured into the coordinate system of the reference hole axis, the spatial positional relationship of each hole centerline is modeled, ensuring its accuracy. The parallelism error is used as the basis for machine tool correction. Moreover, users can choose the more efficient measurement method to assemble the measuring device according to the number of holes to be measured. Through multiple sets of measurement data, the measurement accuracy is improved. By distributing the installation positions of the displacement sensors, the problem of displacement sensors being too large to be installed simultaneously is solved. Attached Figure Description

[0105] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0106] Figure 1 This is a flowchart of the method of the present invention;

[0107] Figure 2 To obtain the displacement sensor parameter diagram;

[0108] Figure 3 A diagram illustrating the method of transforming L to l;

[0109] Figure 4 A schematic diagram showing the measurement of the centerline positions of the two holes;

[0110] Figure 5 This is an overall structural diagram of the device of the present invention;

[0111] Figure 6 This is a detailed structural diagram of the displacement sensor assembly of the present invention;

[0112] Figure 7 This is a schematic diagram of the structure of the present invention installed on a hole-system workpiece. Detailed Implementation

[0113] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0114] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0115] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0116] like Figure 1 As shown, a method for measuring the parallelism error of a hole system workpiece includes the following steps:

[0117] S1: After determining the number of displacement sensors to be installed for the reference hole based on the simulation, install the displacement sensors in a circular arrangement on the connecting frame. At the same time, install the displacement sensors required for the other holes to be measured in the same way. The number of displacement sensors required for the other holes to be measured is the same as that for the reference hole. The measuring device is now installed.

[0118] S2: Determine the installation angle θ and installation height h of the displacement sensor for each hole on the connecting frame, and establish a spatial rectangular coordinate system σ2 on the axis perpendicular to the connecting frame for each hole;

[0119] S3: Use the installed measuring device to measure a standard workpiece with known parallelism, compare the measured value with the standard value, calibrate the measuring device, and then measure the workpiece to be measured.

[0120] S4: Determine the coordinates of the centerline l1 of the datum hole in the datum hole connecting frame coordinate system σ1;

[0121] S5: Determine the coordinates of the centerline l2 of the remaining holes to be measured in the coordinate system σ2 of the connecting frame of the remaining holes to be measured;

[0122] S6: Unify the coordinate system σ2 of the remaining test hole connection frame and the coordinate system σ1 of the reference hole connection frame;

[0123] S7: Establish the coordinate system σ′ of the reference hole centerline l1, and determine the coordinates of the centerlines l2 of the other holes to be measured in the coordinate system σ′ of the reference hole centerline l1;

[0124] S8: Determine the spatial linear relationship between l1 and l2. 1-2 And calculate the parallelism;

[0125] S9: Change the position of the measuring device relative to the workpiece being measured, return to S4, and perform parallelism measurements at different positions.

[0126] By unifying the centerline coordinates of each hole into its respective connecting frame coordinate system, and then unifying the connecting frame coordinate systems of the remaining holes to be measured with the coordinate system of the reference hole connecting frame, a reference hole centerline coordinate system is established with the centerline of the reference hole as the reference line. The centerline coordinates of the remaining holes to be measured are then unified into the reference hole centerline coordinate system. This ensures that the centerline of the reference hole and the centerlines of the remaining holes to be measured are in the same coordinate system. The spatial linear position relationship is then determined, and the parallelism is obtained. After comparing with the standard, the parallelism error is obtained, providing evidence for the correction of the machine tool.

[0127] like Figure 3 As shown, the specific steps of S1 are as follows:

[0128] Let L be a straight line in three-dimensional space, and l be the center line of the hole near the straight line L. Establish a spatial rectangular coordinate system σ = [O; X, Y, Z] on the straight line L, so that the Z axis coincides with L. Then, transform L by rotating it around the X axis by an angle α, moving it along the X axis by a distance e, rotating it around the Z axis by an angle β, and moving it along the Z axis by a distance d.

[0129] The positional relationship between two spatial lines L and l is uniquely represented by ζ:

[0130] ζ=(α,e,β,d) (1)

[0131] Where α is the rotation angle of L around the X-axis; e is the distance L moves along the X-axis; β is the rotation angle of L around the Z-axis; and d is the distance L moves along the Z-axis.

[0132] Make the initial position of l coincide with L, and make the target position of l the final position. During the transformation from the initial position to the final position, the pose change of the cylindrical surface of the hole is consistent with the center line l of the hole.

[0133] Let P be the coordinates of a point on the cylindrical surface of the hole. i (x i y i , z i ), (i = 1, 2, 3…), according to formula (1), establish P i The relationship with ζ:

[0134] (xi cosβ-e+y i sinβ) 2 +[(z i -h)sinα+y i cosαcosβ-x i cosαsinβ] 2 =r 2 (2)

[0135] Where r represents the radius of the hole;

[0136] Let point P be on the cylindrical surface of the hole. i The function is gf i :

[0137] gf i =(x i cosβ-e+y i sinβ) 2 +[(z i -h)sinα+y i cosαcosβ-x i cosαsinβ] 2 -r 2 (3)

[0138] Let the objective function be F:

[0139]

[0140] The minimum value of the objective function is obtained by using an optimization function. The simulation results show that the unique solution of ζ can only be obtained when i≥5. Therefore, the reference hole requires at least five displacement sensors, and the number of displacement sensors required for the other holes to be measured is the same as that for the reference hole.

[0141] like Figure 4 As shown, the specific steps of S2 are as follows:

[0142] Let the axis of the connecting bracket for mounting the reference hole be L1, and let axis L1 be perpendicular to the connecting bracket. Let the center line of the reference hole be l1. Let the axis of the connecting bracket for mounting the other holes to be measured be L2, and let axis L2 be perpendicular to the connecting bracket. Let the center line of the other holes to be measured be l2.

[0143] Establish a spatial rectangular coordinate system σ1 = [O1; X1, Y1, Z1] on axis L1, with the Z1 axis coinciding with L1. Five displacement sensors are defined by E. i (i = 1, 2, 3, 4, 5), installation angle is θ i The installation height is h i Establish a spatial rectangular coordinate system σ2 = [O2; X2, Y2, Z2] on axis L2, making the Z2 axis coincide with L2. Five displacement sensors are defined by E.j (j=1, 2, 3, 4, 5), installation angle is θ j The installation height is h j .

[0144] like Figure 2 As shown, the specific steps of S4 are as follows:

[0145] S401: Determine the positional relationship ζ1 between the connecting bracket axis L1 of the reference hole and the center line l1 of the reference hole;

[0146] L1 is rotated by an angle α1 around the X1 axis, moved by a distance e1 along the X1 axis, rotated by an angle β1 around the Z1 axis, and moved by a distance d1 along the Z1 axis before being transformed into L1.

[0147] The positional relationship between two spatial lines L1 and l1 is uniquely represented by ζ1:

[0148] ζ1=(α1, e1, β1, d1) (5)

[0149] Where α1 is the rotation angle of L1 around the X1 axis, e1 is the distance L1 moves along the X1 axis, β1 is the rotation angle of L1 around the Z1 axis, and d1 is the distance L1 moves along the Z1 axis.

[0150] S402: Based on ζ1 in S401, the coordinates of the centerline l1 of the reference hole in the reference hole connecting frame coordinate system σ1 are obtained by transformation matrix;

[0151] Make the initial position of l1 coincide with L1, and make the target position of l1 the final position. During the process of changing from the initial position to the final position, the pose change of the reference hole cylindrical surface is consistent with the center line l1 of the reference hole.

[0152] According to formula (5), the sensor reading S is established. i The relationship with ζ1:

[0153]

[0154] Among them, S i D represents the reading of the i-th displacement sensor measuring the reference hole. i θ represents the distance from the zero point of the displacement sensor probe to the Z1 axis. i h represents the installation angle of the displacement sensor. i The value r represents the installation height of the displacement sensor, and r1 represents the radius of the reference hole.

[0155] Let the displacement sensor reading S be... i The function is f i :

[0156]

[0157] Let the objective function be F1:

[0158]

[0159] Where f1 is a function of displacement sensor reading S1, f2 is a function of displacement sensor reading S2, f3 is a function of displacement sensor reading S3, f4 is a function of displacement sensor reading S4, and f5 is a function of displacement sensor reading S5.

[0160] ζ1 can be obtained by finding the minimum value of the objective function using the optimization function;

[0161] The formulas for the rotation and translation matrices Rot(x, α), Rot(z, β), Trans(e 0 0), and Trans(0 0 d) are as follows:

[0162]

[0163] The coordinate transformation matrix from L1 to l1 is denoted as T1:

[0164] T1=Trans(0 0 d1)Rot(Z1,β1)Trans(e1 0 0)Rot(X1,α1) (10)

[0165] Let the coordinates of a point on the Z1 axis in σ1 be (0, 0, qz), and the coordinates of a point on the l1 axis in σ1 be (x, y, qz). p1 y p1 , z p1 ),but:

[0166]

[0167] That is, the coordinates of the center line l1 of the reference hole in the coordinate system σ1 of the reference hole connecting frame are obtained.

[0168] The specific steps of S5 are as follows:

[0169] S501: Determine the positional relationship ζ2 between the connecting frame axis L2 and the center line l2 of the remaining holes to be tested;

[0170] L2 is rotated around the X2 axis by an angle α2, moved along the X2 axis by a distance e2, rotated around the Z2 axis by an angle β2, and moved along the Z2 axis by a distance d2 before being transformed into l2.

[0171] The positional relationship between two spatial lines L2 and l2 is uniquely represented by ζ2:

[0172] ζ2=(α2, e2, β2, d2) (12)

[0173] Where α2 is the rotation angle of L2 around the X2 axis, e2 is the distance L2 moves along the X2 axis, β2 is the rotation angle of L2 around the Z2 axis, and d2 is the distance L2 moves along the Z2 axis;

[0174] S502: Based on ζ2 in S501, the coordinates of the center line l2 of the remaining test holes in the coordinate system σ2 of the connecting frame of the remaining test holes are obtained by transformation matrix;

[0175] Make the initial position of l2 coincide with L2, and make the target position of l2 the final position. During the process of changing from the initial position to the final position, the pose change of the cylindrical surface of the hole is consistent with the center line of the hole.

[0176] According to formula (12), the sensor reading S is established. j The relationship with ζ2:

[0177]

[0178] Among them, S j D represents the reading of the j-th sensor used to measure the remaining holes to be measured. j θ represents the distance from the zero point of the displacement sensor probe to the Z2 axis. j h represents the installation angle of the displacement sensor. j r1 represents the installation height of the displacement sensor, and r2 represents the radius of the remaining test holes 2;

[0179] Let the displacement sensor reading S be... j The function is g j :

[0180]

[0181] Let the objective function be F2:

[0182]

[0183] Where g1 is a function of displacement sensor reading S1, g2 is a function of displacement sensor reading S2, g3 is a function of displacement sensor reading S3, g4 is a function of displacement sensor reading S4, and g5 is a function of displacement sensor reading S5.

[0184] ζ2 can be obtained by finding the minimum value of the objective function using the optimization function;

[0185] The coordinate transformation matrix from L2 to l2 is denoted as T2:

[0186] T2=Trans(0 0 d2)Rot(Z1,β2)Trans(e2 0 0)Rot(X1,α2) (16)

[0187] Let the coordinates of a point on the Z2 axis in σ2 be (0, 0, qz2), and the coordinates of a point on l2 in σ2 be (x, qz2 ... p2 y p2 , z p2 ),but:

[0188]

[0189] That is, the coordinates of the center line l2 of the other holes to be tested in the coordinate system σ2 of the connecting frame of the other holes to be tested are obtained.

[0190] The specific steps of S6 are as follows:

[0191] The matrix that transforms the coordinate system from σ2 to σ1 is denoted as M. 12 Let the coordinates of the origin of σ2 in σ1 be (x...). o2 y o2 , z o2 If σ2→σ1, then σ2→σ1:

[0192]

[0193] Let the coordinates of a point on l2 in σ1 be (x p21 y p21 , z p2] According to formula (17), then:

[0194]

[0195] This means unifying the coordinate system σ2 of the remaining test hole connection frame and the coordinate system σ1 of the reference hole connection frame.

[0196] like Figure 4 As shown, the specific steps of S7 are as follows:

[0197] Establish a spatial rectangular coordinate system σ′ = [O′; X′, Y′, Z′] on l1; make the Z′ axis coincide with l1; let the coordinates of a point on l1 in σ′ be (x, Y, Z′). p1 ′,y p1 ′,z p1 '),but:

[0198]

[0199] Let the coordinates of a point on l2 in σ′ be (x p21 ′,y p21 ′,z p21 According to formula (19), then:

[0200]

[0201] That is, the coordinates of the center line l2 of the other holes to be tested in the coordinate system σ′ of the center line l1 of the reference hole can be obtained.

[0202] The specific steps of S8 are as follows:

[0203] The spatial linear positional relationship ζ between l1 and l2 is obtained. 1-2 :

[0204] ζ 1-2 =(α 1-2 e 1-2 ,β 1-2 d 1-2 ) (twenty two)

[0205] Using the centerline l1 of the reference hole as the reference line, measure the parallelism of the centerlines l2 of the other holes to be measured relative to l1; then the magnitude of the parallelism t is... pa The calculation formula is:

[0206] t pa =Htanω (23)

[0207] Where H is the hole depth; ω is the angle between the two spatial lines; ω = α 1-2 ;

[0208] In three-dimensional space, parallelism errors of the same magnitude can have different directions; therefore, a direction angle is introduced. To indicate the direction of parallelism error, i.e.

[0209] Let the measurement result be t. pan , The parallelism is then characterized as follows:

[0210]

[0211] Where t par Indicates the degree of parallelism. Indicates the direction of parallelism.

[0212] like Figures 5-7 As shown, a device for measuring the parallelism error of a hole system workpiece includes an adjustable connecting frame 1 and a measuring component 2. At least two sets of mutually parallel measuring components 2 are installed on the adjustable connecting frame 1. The measuring components 2 are vertically installed on the adjustable connecting frame 1. The measuring component 2 includes at least five displacement sensor components 21 distributed along the circumferential direction.

[0213] By integrating multiple displacement sensors to jointly measure the parallelism of a hole system workpiece, this method solves the problem of needing to integrate multiple displacement sensors to measure hole parallelism. Furthermore, it enables the use of this measuring device to model the spatial positional relationship of the centerlines of each hole under test, achieving the representation of the centerlines of each hole under test in the same coordinate system, and finally obtaining the parallelism error. Moreover, the measurement does not require disassembling the workpiece, allowing for direct on-machine measurement, making it more convenient to use. Additionally, multiple sets of data can be obtained from different positions, resulting in more accurate parallelism measurement results.

[0214] For ease of measurement, the displacement sensor assembly 21 includes a displacement sensor 211, a measuring rod 212, a probe 213, and an adjustable mounting base 214. One end of the measuring rod 212 is connected to the displacement sensor 211, and the other end is connected to the probe 213. The displacement sensor 211 is mounted on the adjustable mounting base 214, and the probe 213 contacts the inner wall of the hole. The measuring rod 212 has a Z-shaped structure. Because the displacement sensor is relatively large, a Z-shaped measuring rod is mounted on it. During measurement, the displacement sensor body does not enter the hole to be measured; only the measuring rod guides the probe into the hole, where it contacts the inner wall. Simultaneously, the adjustable mounting base adjusts the distance between each displacement sensor assembly and the adjustable connecting frame, ensuring that the adjustable connecting frame is parallel to the workpiece during measurement. This improves measurement accuracy and solves the problem of the displacement sensors being too large to be installed simultaneously.

[0215] When installing the adjustable connecting frame on the workpiece with holes, V-blocks are installed on the adjustable connecting frame to maintain the stability of the measuring device, further improving the stability of the device. In order to facilitate the installation of displacement sensors, a connecting shaft perpendicular to the adjustable connecting frame is installed on the adjustable connecting frame, and the displacement sensor is installed on the connecting shaft. Alternatively, an adjustable connecting frame with uniform holes can be used to install the displacement sensor.

[0216] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0217] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring the parallelism error of a hole system workpiece, characterized in that: Includes the following steps: S1: After determining the number of displacement sensors to be installed for the reference hole based on the simulation, install the displacement sensors in a circular arrangement on the connecting frame. At the same time, install the displacement sensors required for the other holes to be measured in the same way. The number of displacement sensors required for the other holes to be measured is the same as that for the reference hole. The measuring device is now installed. The specific steps of S1 are as follows: Let L be a straight line in three-dimensional space, and l be the center line of the hole near the straight line L. Establish a spatial rectangular coordinate system σ=[O;X,Y,Z] on the straight line L, so that the Z axis coincides with L. Then, transform L by rotating it around the X axis by an angle α, moving it along the X axis by a distance e, rotating it around the Z axis by an angle β, and moving it along the Z axis by a distance d. The positional relationship between two spatial lines L and l is uniquely represented by ζ: (1) Where α is the rotation angle of L around the X-axis; e is the distance L moves along the X-axis; β is the rotation angle of L around the Z-axis; and d is the distance L moves along the Z-axis. Make the initial position of l coincide with L, and make the target position of l the final position. During the transformation from the initial position to the final position, the pose change of the cylindrical surface of the hole is consistent with the center line l of the hole. Let P be the coordinates of a point on the cylindrical surface of the hole. i (x i ,y i ,z i ), (i=1,2,3···), according to formula (1), establish P i The relationship with ζ: (2) Where r represents the radius of the hole; Let point P be on the cylindrical surface of the hole. i The function is gf i : (3) Let the objective function be F: (4) The minimum value of the objective function is solved by using an optimization function. The simulation results show that the unique solution of ζ can only be found when i ≥ 5. Therefore, the reference hole requires at least five displacement sensors, and the number of displacement sensors required for the other holes to be measured is the same as that for the reference hole. S2: Determine the installation angle θ and installation height h of the displacement sensors for each hole on the connecting frame, and establish a spatial rectangular coordinate system σ on the axis perpendicular to the connecting frame for each hole. k ; S3: Use the installed measuring device to measure a standard workpiece with known parallelism, compare the measured value with the standard value, calibrate the measuring device, and then measure the workpiece to be measured. S4: Determine the coordinates of the centerline l1 of the datum hole in the datum hole connecting frame coordinate system σ1; S5: Determine the centerline of the remaining holes to be tested. k In the coordinate system σ of the remaining holes to be measured k Coordinates in; S6: For the coordinate system σ of the remaining holes to be measured, k Unify the coordinate system σ1 with the reference hole connecting frame; S7: Establish the coordinate system σ´ of the reference hole centerline l1, and determine the centerlines l of the remaining holes to be measured. k The coordinates in the coordinate system σ´ of the center line l1 of the reference hole; S8: Determine l1 and l k Spatial linear positional relationship ζ 1-k And calculate the parallelism; S9: Change the position of the measuring device relative to the workpiece being measured, return to S4, and perform parallelism measurements at different positions.

2. The method for measuring the parallelism error of a hole system workpiece according to claim 1, characterized in that: The specific steps of S2 are as follows: Let the axis of the connecting bracket for mounting the reference hole be L1, and let axis L1 be perpendicular to the connecting bracket. Let the centerline of the reference hole be l1. Let the axis of the connecting bracket for mounting the other holes to be measured be L. k (k=2,3,4,…), axis L k Perpendicular to the connecting frame, the centerline of the remaining holes to be measured is l. k ; Establish a spatial rectangular coordinate system σ1=[O1;X1,Y1,Z1] on axis L1, with the Z1 axis coinciding with L1. Five displacement sensors are defined by E. i (i=1,2,3,4,5), with an installation angle of θ i The installation height is h i ; on axis L k Establish a spatial rectangular coordinate system σ on the above k =[O k ;X k ,Y k Z k ], making Z k Axis and L k Overlapping, five displacement sensors for E j (j=1,2,3,4,5), installation angle is θ j The installation height is h j .

3. The method for measuring the parallelism error of a hole system workpiece according to claim 2, characterized in that: The specific steps of S4 are as follows: S401: Determine the positional relationship ζ1 between the connecting bracket axis L1 of the reference hole and the center line l1 of the reference hole; L1 is rotated by an angle α1 around the X1 axis, moved by a distance e1 along the X1 axis, rotated by an angle β1 around the Z1 axis, and moved by a distance d1 along the Z1 axis before being transformed into L1. The positional relationship between two spatial lines L1 and l1 is uniquely represented by ζ1: (5) Where α1 is the rotation angle of L1 around the X1 axis, e1 is the distance L1 moves along the X1 axis, β1 is the rotation angle of L1 around the Z1 axis, and d1 is the distance L1 moves along the Z1 axis. S402: Based on ζ1 in S401, the coordinates of the centerline l1 of the reference hole in the reference hole connecting frame coordinate system σ1 are obtained by transformation matrix; Make the initial position of l1 coincide with L1, and make the target position of l1 the final position. During the process of changing from the initial position to the final position, the pose change of the reference hole cylindrical surface is consistent with the center line l1 of the reference hole. Based on formula (5), establish the sensor reading S i The relationship with ζ1: (6) Among them, S i D represents the reading of the i-th displacement sensor measuring the reference hole. i θ represents the distance from the zero point of the displacement sensor probe to the Z1 axis. i h represents the installation angle of the displacement sensor. i The value r represents the installation height of the displacement sensor, and r1 represents the radius of the reference hole. Let the displacement sensor reading S be... i The function is f i : (7) Let the objective function be F1: (8) Where f1 is a function of displacement sensor reading S1, f2 is a function of displacement sensor reading S2, f3 is a function of displacement sensor reading S3, f4 is a function of displacement sensor reading S4, and f5 is a function of displacement sensor reading S5. ζ1 can be obtained by finding the minimum value of the objective function using the optimization function; The formulas for the rotation and translation matrices Rot(x,α), Rot(z,β), Trans(e 0 0), and Trans(0 0 d) are as follows: ， ； ， (9) The coordinate transformation matrix from L1 to l1 is denoted as T1: (10) Let the coordinates of a point on the Z1 axis in σ1 be (0, 0, qz), and the coordinates of a point on the l1 axis in σ1 be (x, qz ... p1 ,y p1 ,z p1 ),but: (11) That is, the coordinates of the center line l1 of the reference hole in the coordinate system σ1 of the reference hole connecting frame are obtained.

4. The method for measuring the parallelism error of a hole system workpiece according to claim 3, characterized in that: The specific steps of S5 are as follows: S501: Determine the axis L of the connecting bracket for the remaining holes to be tested. k and the center line of the other holes to be tested l k Positional relationship ζ k ; L k Circling X in sequence k Axis rotation angle α k Along X k Axis travel distance e k , around Z k Axis rotation angle β k Along Z k Axis movement distance d k After transformation to l k ; Two spatial lines L k With l k Positional relationships are represented by ζ k Unique representation: (12) Where, α k For L k Around X k Axis rotation angle, e k For L k Along X k Axis travel distance, β k For L k Around Z k Axis rotation angle, d k For L k Along Z k Axis travel distance; S502: According to ζ in S501 k The centerline l of the remaining holes to be tested is obtained by transforming the matrix. k In the coordinate system σ of the remaining holes to be measured k Coordinates in; Make l k The initial position and L k Overlap, making l k The target position is the final position. During the transformation from the initial position to the final position, the pose change of the cylindrical surface of the hole is consistent with the center line of the hole. Based on formula (12), establish the sensor reading S j With ζ k Relationship: (13) Among them, S j D represents the reading of the j-th sensor used to measure the remaining holes to be measured. j Indicates the zero position to Z position of the displacement sensor probe. k Distance between axes, θ j h represents the installation angle of the displacement sensor. j The value r represents the installation height of the displacement sensor. k This represents the radius of the remaining test holes k; Let the displacement sensor reading S be... j The function is g j : (14) Let the objective function F k : (15) Where g1 is a function of displacement sensor reading S1, g2 is a function of displacement sensor reading S2, g3 is a function of displacement sensor reading S3, g4 is a function of displacement sensor reading S4, and g5 is a function of displacement sensor reading S5. By finding the minimum value of the objective function using the optimization function, ζ can be obtained. k ; From L k Transform to l k The coordinate transformation matrix is ​​denoted as T. k : (16) Let Z k Points on the axis at σ k The coordinates in the equation are (0, 0, qz). k ), l k The point on σ k The coordinates in (x) pk ,y pk ,z pk ),but: (17) That is, the center line l of the remaining holes to be measured is obtained. k In the coordinate system σ of the remaining holes to be measured k The coordinates in the diagram.

5. The method for measuring the parallelism error of a hole system workpiece according to claim 4, characterized in that: The specific steps of S6 are as follows: From coordinate system σ k The matrix transformed to σ1 is denoted as M. 1k Let σ k The coordinates of the origin in σ1 are (x ok ,y ok ,z ok ), then σ k →σ1: (18) Let l k The coordinates of the point on the x-axis in σ1 are (x-y) pk1 ,y pk1 ,z pk1 According to formula (17), then: (19) That is, to complete the coordinate system σ of the remaining test holes connecting frame k The coordinate system σ1 of the reference hole connecting frame is unified.

6. The method for measuring the parallelism error of a hole system workpiece according to claim 5, characterized in that: The specific steps of S7 are as follows: Establish a spatial rectangular coordinate system σ´=[O´;X´,Y´,Z´] on l1; make the Z´ axis coincide with l1; let the coordinates of a point on l1 in σ´ be (x...X´,Y´,Z´). p1 ´,y p1 ´,z p1 but: (20) Let l k The coordinates of the point on the line are (x) in σ'. pk1 ´,y pk1 ´,z pk1 According to formula (19), then: (21) That is, the center line l of the remaining holes to be measured is obtained. k The coordinates in the coordinate system σ´ of the center line l1 of the reference hole.

7. The method for measuring the parallelism error of a hole system workpiece according to claim 6, characterized in that: The specific steps of S8 are as follows: Find l1 and l k Spatial linear positional relationship ζ 1-k : (22) Using the center line l1 of the reference hole as the reference line, measure the center lines l of the other holes to be measured. k The parallelism relative to l1; then the parallelism magnitude t pa The calculation formula is: (23) Where H is the hole depth; ω is the angle between the two spatial lines; ω = α 1-k ; In three-dimensional space, parallelism errors of the same magnitude can have different directions; therefore, a direction angle φ (0~360°) is introduced to represent the direction of the parallelism error, i.e., φ=β. 1-k ; Let the measurement result be t. pan , φ n If n=1,2,3…, then the parallelism is characterized as follows: (24) Where t par φ represents the degree of parallelism. r Indicates the direction of parallelism.

8. The method for measuring the parallelism error of a hole system workpiece according to claim 7, characterized in that: It includes an adjustable connecting frame (1) and a measuring component (2). At least two sets of parallel measuring components (2) are installed on the adjustable connecting frame (1). The measuring components (2) are vertically installed on the adjustable connecting frame (1). The measuring component (2) includes at least five displacement sensor components (21) distributed along the circumferential direction.

9. The method for measuring the parallelism error of a hole system workpiece according to claim 8, characterized in that: The displacement sensor assembly (21) includes a displacement sensor (211), a probe (212), a probe (213), and an adjustable mounting base (214). One end of the probe (212) is connected to the displacement sensor (211), and the other end is connected to the probe (213). The displacement sensor (211) is mounted on the adjustable mounting base (214). The probe (213) is in contact with the inner wall of the hole. The probe (212) has a Z-shaped structure.

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