Method for establishing coordinate system for three-coordinate measurement of curved glass and supporting device thereof

Abstract

The application discloses a kind of curved surface glass three-coordinate measurement coordinate system establishment method and its supporting device, belong to three-coordinate measurement technical field, comprising: according to the appearance of curved surface glass is installed in the appropriate position of measuring machine measurement support device;Curved surface glass is placed on the gear of support device;Extract two positioning pins on curved surface glass and its plane and construct two intersection points;The symmetry point c of two intersection points is constructed, and the Z direction coordinate value of point c is recorded;According to c point coordinate extraction tangent L and determine the normal of the theoretical coordinate value of system point e;Calculate the angle of positioning pin in whole vehicle coordinate system;Through adjusting dial plate simulation glass in the angle of whole vehicle;Positioning measuring machine to the X, Z position of point e;System measurement evaluation is established;The establishment method and its supporting device can realize the coordinate system of three-coordinate measurement fast establishment, can carry out subsequent profile measurement, without needing to carry out coordinate system multiple iteration, improve detection result accuracy and detection efficiency.

Description

Technical Field

[0001] This invention belongs to the field of coordinate measuring technology, specifically relating to a method for establishing a coordinate system and a supporting device for coordinate measuring of curved glass. Background Technology

[0002] In recent years, my country's demand for automobile products has been increasing. In the automobile production process, automotive glass is one of the important materials. With the continuous development of production technology, high-end automobile products have increasingly higher requirements for the quality of automotive glass. The shape quality and appearance dimensions of automotive glass are important indicators for measuring whether automotive glass production is qualified.

[0003] With the development of measurement technology, coordinate measuring machines (CMMs) have emerged. A CMM is a measuring device capable of calculating various geometric shapes and dimensions within a three-dimensional measurable space based on point data returned by a probe system and using software. The basic principle of a CMM is to place the part to be measured within its permissible measurement space, accurately measure the XYZ coordinates of points on the part's surface, and then process these coordinates using a computer to fit and form measurement elements such as circles, spheres, cylinders, cones, and curved surfaces. Mathematical calculations are then used to derive its shape, positional tolerances, and other geometric data. Due to its high accuracy and repeatability, CMMs are widely used for measuring the geometric dimensions, shape, and position of objects.

[0004] In existing technologies, coordinate measuring machines (CMMs) are commonly used to measure curved glass. The process of measuring curved glass parts using a CMM mainly includes: part measurement and positioning, coordinate system establishment, and measurement analysis. During CMM measurement, the measurement reference is usually established by contacting points on the curved glass surface using the CMM. The goal is to select as many reasonably positioned points as possible on the curved glass surface. The coordinate system is then optimized through multiple measurements and iterations to continuously bring it closer to the theoretical value. However, the system establishment process is slow and inefficient for batch measurements. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a coordinate system establishment method and supporting device for coordinate measurement of curved glass, which enables rapid establishment of the coordinate system for coordinate measurement, allowing for subsequent surface measurement without multiple iterations of the coordinate system, thereby improving the accuracy and efficiency of the detection results.

[0006] This invention is achieved through the following technical solution:

[0007] A method for establishing a coordinate system for coordinate measurement of curved glass includes the following steps:

[0008] Step S1: Install the measuring support device at a suitable position on the measuring machine according to the shape of the curved glass;

[0009] Step S2: Place the curved glass on the gear of the support device, ensuring it does not tip over or shift.

[0010] Step S3: Extract the two positioning pins on the curved glass and their corresponding planes, and construct two intersection points a and b. These two intersection points are located at the two ends of the bottom edge of the curved glass, respectively.

[0011] Step S4: Construct the symmetrical point c of intersection points a and b, and record the Z-coordinate value of point c;

[0012] Step S5: Capture data in the data acquisition window of the measurement software, draw a theoretical intersection line on the digital model, modify the Z value of this line in the capture window to the Z coordinate value of the symmetrical point c, generate a slice curve line L, select the optimal point e as the third point, and record the X, Y, Z coordinate values ​​of point e and its N value. X N Y N Z value;

[0013] S6. In the measurement program, edit a measuring point and set its X, Y, Z coordinates and N. X N Y N Z The value is the same as that of point e;

[0014] S7. The X and Y coordinates of point e in the machine coordinate system have been determined. The Z coordinate can be obtained by calculating the difference between the X coordinate value of point e in the digital model and the Z value of the symmetrical point c in the machine coordinate system, shifting the measuring ball of the measuring machine upward, and can be obtained through an automatic positioning measuring machine.

[0015] On the other hand, the present invention also provides a support device for establishing a coordinate system for coordinate measurement of curved glass, including a measuring machine plate 14. One end of the measuring machine plate 14 is fixed with two opposing first bases 1 with internal threads, and a worm gear 3 with a scale 8 is connected between the two first bases 1. The other end is fixed with a third base 11, and a track 10 is fixed on the third base 11. A second base 2 is arranged between the two first bases 1 and the third base 11. A shaft 12 is connected to the second base 2. An L-shaped bracket 5 is fitted in the middle of the shaft 12 for installing an adjustable center 4. Gears 7 and bearings 9 are respectively connected to both ends of the shaft 12. The gears 7 mesh with the worm gear 3 and are used to place the curved glass. The bearings 9 are installed in the track 10.

[0016] Furthermore, the two first bases 1, the second base 2, and the third base 11 are all arranged in parallel relative to each other, with the second base 2 located in the middle position between the first base 1 and the third base 11.

[0017] Furthermore, the shaft 12 is arranged parallel to the measuring machine plate 14.

[0018] Furthermore, the first base 1 and the second base 2 are at the same height.

[0019] Furthermore, the gear 7 and the bearing 9 are respectively fixed to the shaft 12 by keys with the same limiting direction.

[0020] Furthermore, the vertical surface of the L-shaped bracket 5 is provided with a matrix of circular holes for mounting the adjustable tip 4.

[0021] Furthermore, the gear 7 has an angle of 3° per tooth, and the upper center line of the gear 7 has an opening with the same thickness as the curved glass 6, and the depth is the same as the center of the gear, which is engaged with a worm gear with an axial tooth pitch of 3mm.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] The present invention provides a coordinate system establishment method and supporting device for three-coordinate measurement of curved glass, which enables rapid establishment of the coordinate system for three-coordinate measurement, allowing for subsequent surface measurement without multiple iterations of the coordinate system, thereby improving the accuracy and efficiency of the detection results. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0025] Figure 1 This is a flowchart illustrating a method for establishing a coordinate system in a three-coordinate measurement of curved glass according to the present invention.

[0026] Figure 2 This is a schematic diagram of the sampling points;

[0027] Figure 3 This is a side view of a support device for establishing a coordinate system for coordinate measurement of curved glass according to the present invention.

[0028] Figure 4 This is a schematic diagram of the overall structure of a support device for establishing a coordinate system for coordinate measurement of curved glass according to the present invention.

[0029] Figure 5This is a schematic diagram of the dial.

[0030] Figure 6 This is a schematic diagram of the measuring device after adjustment.

[0031] Figure 7 Schematic diagram of the measurement and sampling process

[0032] In the picture:

[0033] First base 1, second base 2, worm gear 3, adjustable center 4, L-shaped bracket 5, glass 6, gear 7, dial 8, bearing 9, track 10, third base 11, shaft 12, positioning pin 13, measuring machine plate 14, measuring rod 15, and measuring machine 16. Detailed Implementation

[0034] To clearly and completely describe the technical solution and its specific working process of the present invention, the specific embodiments of the present invention are as follows, in conjunction with the accompanying drawings:

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0038] The principle of the coordinate system establishment method for coordinate measurement of curved glass provided in this embodiment is as follows:

[0039] In the machine coordinate system, the base plane of the measuring equipment is the XY plane. When the car is mounted on the measuring machine, the three axes of the vehicle coordinate system and the machine coordinate system are consistent: the front of the car is X-, the left side of the car is Y-, and the roof is Z+. The XY plane of the equipment base plate and the XY plane of the vehicle coordinate system are aligned. When only one piece of glass is being inspected, it is impossible to place it within the entire vehicle and measure it in its specific position within the vehicle coordinate system. When measuring a single part arbitrarily on the measuring machine, the coordinate system measured using the digital model does not match the machine coordinate system. Establishing a plane requires three points. For a glass with two locating pins, the pins have positioning requirements with the vehicle body during assembly, which are the RPS datums. Therefore, these two pins can be used as the constituent points of the first datum plane for establishing the system, as follows:

[0040] 1. Determine the third point on the first reference plane for establishing the system;

[0041] Extract two locating pins from the digital model and their corresponding planes to form two intersection points. These two intersection points are located at the two ends of the base (long side) of the triangular glass, covering the outermost perimeter of this curved part. When establishing a coordinate system for a part, the plane constraining the first axis should be as large as possible. Therefore, the third point should ideally be selected at the apex corresponding to the base of the triangular glass. These three selected points essentially form the first reference point of the coordinate system, representing the outer perimeter of the triangular glass and with relatively balanced centroids.

[0042] II. Selection;

[0043] In the start system, manually measure the extracted plane and cylinder, calculate the theoretical and actual values ​​of the two intersection points, and observe that the actual and theoretical values, as well as the normal values, of these two intersection points do not match the actual values. For example, the long side of the glass placed on the gear opening, which is the side aligned with the X-axis on the measuring machine, is vertical in the whole vehicle and parallel to the Z-axis of the whole vehicle. At this point, construct a symmetrical point between the two intersection points. The X value of this point corresponds to the Z value in the whole vehicle coordinate system. Record the theoretical Z value of the symmetrical point. Then open the Extract Element window and extract a tangent line from the digital model. The position of the curve is changed in the coordinate value extraction window. Input the theoretical Z-value of the symmetry point that was just recorded. A tangent line will then appear on the digital model. This tangent line will create a cross-sectional curve of the surface model along the Z-coordinate of the symmetry point. Edit the strategy for this cross-sectional curve to multiple measurement points. Then, open all the measurement values ​​and normals of these measurement points. Select measurement points as close as possible to the angle corresponding to the long side of the bottom of the triangular glass to maximize the determination of the datum plane for system establishment. The selected surface point is now on the theoretical digital model. Record its XYZ values ​​and the NX, NY, and NZ direction values ​​respectively. Then, edit a surface measurement point in the measurement software. Manually input the XYZ values ​​and the NX, NY, and NZ direction values ​​of this point from the theoretical values ​​of the third point selected in the tangent line of the digital model that best establishes the system. The X-value of this point should be consistent with the X-value of the symmetry point. This corresponds to the Z-value in the theoretical digital model.

[0044] III. Measurement;

[0045] Three measurement points were determined for the coordinate plane. Two of the intersection points have been measured, but the theoretical and measured values ​​do not match. The former is the theoretical value in the vehicle coordinate system, while the latter is the measured value of the glass in the machine coordinate system. The same applies to the symmetrical points of the two intersection points. The third point does not have any clear features on the curved glass that allow people to accurately locate the measurement point by visual inspection. The measuring machine can be positioned using the X and Z values ​​of the symmetrical point, so that the position coordinates of the measuring ball are at the XZ position of the symmetrical point of the intersection of the two positioning pins extracted from the digital model. The X value at this time corresponds to the Z value in the whole vehicle. The Z value of the third point selected in the tangent of the digital model must be consistent with the current X value position of the measuring machine. The theoretical X value of the selected third point, the difference between the theoretical X value of the symmetrical point and the X value of the third point selected by the tangent is the Z value difference of the part in the machine coordinate system. Adding this difference to the current Z value is the Z value of the third point. Here, the theoretical XZ position of the third point can be obtained by automatically positioning the measuring machine. When a point has been positioned in two directions, lock the measuring machine in these two positions, and then manually probe along the normal direction to obtain the coordinates of the third point. The plane determination is completed.

[0046] Example 1

[0047] like Figure 1The diagram shown is a flowchart illustrating a method for establishing a coordinate system in a three-coordinate measurement of curved glass according to this embodiment. The method specifically includes the following steps:

[0048] Step S1: Install the measuring support device at a suitable position on the measuring machine according to the shape of the curved glass;

[0049] Step S2: Place the curved glass on the gear of the support device, ensuring it does not tip over or shift.

[0050] Step S3: Extract the two positioning pins on the curved glass and their corresponding planes, and construct two intersection points a and b. These two intersection points are located at the two ends of the bottom edge of the curved glass, respectively.

[0051] Step S4: Construct the symmetrical point c of intersection points a and b, and record the Z-coordinate value of point c;

[0052] Step S5: Capture data in the data acquisition window of the measurement software, draw a theoretical intersection line on the digital model, modify the Z value of this line in the capture window to the Z coordinate value of the symmetrical point c, generate a slice curve line L, select the optimal point e as the third point, and record the X, Y, Z coordinate values ​​of point e and its N value. X N Y N Z value;

[0053] S6. In the measurement program, edit a measuring point and set its X, Y, Z coordinates and N. X N Y N Z The value is the same as that of point e;

[0054] S7. The X and Y coordinates of point e in the machine coordinate system have been determined. The Z coordinate can be obtained by calculating the difference between the X coordinate value of point e in the digital model and the Z value of the symmetrical point c in the machine coordinate system, shifting the measuring ball of the measuring machine upward, and can be obtained through an automatic positioning measuring machine.

[0055] Example 2

[0056] This embodiment provides a method for establishing a coordinate system for coordinate measurement of curved glass. Taking the normal of the positioning pin axis NX 0NY 0.9962NZ 0.0871 as an example, this pin axis has only one axis direction angle. According to the cosine theorem, arccos∠0.9962=4.996°, that is, the angle between the pin axis and the Y+ axis of the coordinate system is 4.996 degrees. In this embodiment, it is set to approximately 5°. The specific steps include the following:

[0057] I. Data Extraction Stage;

[0058] S1. Place the glass at the center opening of the gear with the same height, ensuring it does not tip over or shift.

[0059] S2. Use a digital model to collect theoretical data of the cylindrical pins, manually measure two cylindrical pins and construct points a and b;

[0060] S3. Construct a symmetrical point c between points a and b, and record the Z coordinate value of point c;

[0061] S4. Construct the third point e (theoretical point) of the system-building plane on the digital model. The principle is as follows: intersect the digital model with a plane in the Z direction that passes through the symmetric point c. After editing the measurement strategy of the intersection line, take a specific point on this intersection line as the third point of the system-building plane.

[0062] S5. Capture data in the data acquisition window of the measurement software, draw a theoretical intersection line on the digital model, and manually modify the Z value of this line in the capture window to the Z coordinate value of the symmetrical point c. Click OK. At this time, a Slicecurve line L is generated in the program. Edit the measurement strategy of this line to make it have more measurement points. Then click to view the number of measurement points window. At this time, you can see the coordinate values ​​of all points and their NX, NY, and NZ values. We need to select the point e closest to one corner of the triangular glass as the third point and record the XYZ coordinate values ​​of point e and their NX, NY, and NZ values.

[0063] S6. In the measurement program, edit a measuring point so that its XYZ coordinates and its NXNYNZ values ​​are the same as those of point e;

[0064] S7. The X and Y coordinates of point e in the machine coordinate system have been determined. The Z coordinate can be obtained by calculating the difference between the X coordinate value of point e in the digital model and the Z value of the symmetrical point c in the machine coordinate system, shifting the measuring ball of the measuring machine upward, and can be obtained through an automatic positioning measuring machine.

[0065] II. Component support components;

[0066] 1. Initial support;

[0067] The curved glass is placed vertically along the X-axis of the measuring machine, avoiding horizontal placement to prevent errors caused by gravitational deformation. A measuring machine plate 14 with a matrix of circular holes is placed on the XY plane of the measuring machine's base plate, with the measuring machine plate 14 aligned with the XY plane of the vehicle body. Figure 3 As shown, two threaded bases 1 are fixed at a suitable position at one end of the measuring machine plate 14. The threads of the bases 1 engage with a worm gear 3 with a scale 8 at one end. Figure 4As shown, a third base 11 with a track 10 is fixed to the other end of the measuring machine plate 14, which mates with the bearing 9. A shaft 12 has gears 7 and bearings 9 installed at both ends, and is fixed to the shaft 12 by keys with the same limiting direction. An L-shaped bracket 5 is fixed to a base 2 with the same height as the worm gear 3 support base 1, installed in the middle of the shaft 12, and locked to the shaft with a key. The vertical surface of the L-shaped bracket 5 has a matrix of round holes. Select the appropriate height of the round holes to install the length adjustable center, so that the glass rests on the center. After the center position is selected, the base is fixed to the base plate of the measuring equipment. The installed shaft should be parallel to the measuring machine plate, and ensure that no displacement occurs in the bases when the gear rotates, and only the shaft drives the central opening of the gear to rotate. Each tooth of the gear at one end of the shaft is 3°, and there is an opening on the upper center line of the gear with the same thickness as the glass and the same depth as the center of the gear, which mates with the worm gear with an axial tooth pitch of 3mm. The bearing at the other end of the shaft is installed in the track connected to the base 3 on the same side. When the gear rotates, the bearing can slide in the track. Place the glass at the opening, ensuring it falls to the bottom. Adjust the probe angle of the machine to 0.0 degrees. Use the measuring rod 15 of the measuring machine 16 as a reference, positioned close to the locating pin of the curved glass 6. Adjust the angle of the curved glass 6 by rotating the dial 8 to drive the gear 7, aligning the normal of the locating pin 13 with the Y-axis of the measuring machine 16. Then, adjust the adjustable position and length of the adjustable tip 4 on the L-shaped bracket 5, so that the curved glass rests against the adjustable tip 4.

[0068] 2. Accurate alignment;

[0069] In the theoretical digital model, the normal direction of the positioning pin axis is: NX 0NY 0.9962NZ 0.0871. The Y-axis angle is 0.9962 - INV - cos⁻¹ = 4.996 degrees, meaning the angle between the pin axis and the Y+ axis of the coordinate system is 4.996 degrees. For example... Figure 4 As shown, the dial in the support device has a standard internal hexagon in the center, which is fixed to one end of the worm gear. The axial tooth pitch of the worm gear is 3mm, and the end face pitch of the gear that mates with the worm gear is also 3mm. One rotation of the dial is 3 degrees, divided into 4 large divisions, each large division being 0.75°, and each large division being divided into 15 small divisions, each small division being 0.5 degrees. One rotation of the dial moves it 3mm towards the leading edge axis, simultaneously causing the gear to rotate one tooth, i.e., the gear rotates 3°. Rotating the dial one and a half times and 10 small divisions is 5°, which is the angle of the locating pin in the vehicle. At this point, the normal direction of the simulated glass in the vehicle is completed. Afterwards, an adjustable support tip is manually placed under the L-shaped bracket for stability. Figure 5 As shown, the measuring support device has been adjusted and positioned, and after being fixed, it is used as a gauge.

[0070] III. Establishment of the system survey;

[0071] Place the curved glass into the adjusted support device. Manually measure the coordinates of two cylindrical pins to obtain the coordinates of points a, b, and c. After selecting point e, automatically position the measuring machine at the XY coordinates of point e. Lock the measuring machine's XY axis stationary and manually measure the Y coordinate of point e along the Y-axis. Use points a, b, and e to construct a plane as the first reference plane for establishing the coordinate system. The line connecting points a and b is the second reference. Take the locating pin where the glass mates with the circular hole on the vehicle body as the center to establish a standard coordinate system. In the edited measurement program, pay attention to the normal direction of each measuring point, such as... Figure 6 As shown, an incorrect probe angle will cause measurement errors. The appropriate probe angle should be selected based on the normal vector direction of the theoretical data for measurement. If the glass is highly rigid, subsequent surface measurements can be performed directly in the standard coordinate system. If the glass is less rigid, a subroutine can be established in the standard coordinate system to create a multi-point iterative best-fit plane to constrain the Y direction of the glass. In this case, the points can be automatically measured in the existing standard coordinate system, improving measurement efficiency.

[0072] Example 3

[0073] like Figure 3 and Figure 4 The diagram shows a structural schematic of a support device for establishing a coordinate system in a coordinate measuring machine for curved glass, according to this embodiment. The support device includes a measuring machine plate 14. Two first bases 1 with internal threads are fixed to opposite sides of one end of the measuring machine plate 14, and a worm gear 3 with a scale 8 is connected between the two first bases 1. A third base 11 is fixed to the other end, and a track 10 is fixed on the third base 11. A second base 2 is provided between the two first bases 1 and the third base 11, and a shaft 12 is connected to the second base 2. An L-shaped bracket 5 is fitted in the middle of the shaft 12 for mounting an adjustable center 4. Gears 7 and bearings 9 are connected to both ends of the shaft 12, respectively. The gears 7 mesh with the worm gear 3 and are used to place the curved glass. The bearings 9 are installed in the track 10.

[0074] The two first bases 1, the second base 2 and the third base 11 are all arranged in parallel relative to each other, with the second base 2 located in the middle position between the first base 1 and the third base 11.

[0075] The shaft 12 is arranged parallel to the measuring machine plate 14.

[0076] The first base 1 and the second base 2 have the same height.

[0077] The gear 7 and bearing 9 are respectively fixed to the shaft 12 by keys with the same limiting direction.

[0078] The L-shaped bracket 5 has a matrix of circular holes on its vertical surface for mounting the adjustable center 4.

[0079] The gear 7 has an angle of 3° per tooth. The upper center line of the gear 7 has an opening with the same thickness as the curved glass 6 and the same depth as the center of the gear. It is engaged with a worm gear with an axial tooth pitch of 3mm.

[0080] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0081] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0082] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for establishing a coordinate system for coordinate measurement of curved glass, characterized in that, Specifically, the steps include the following: Step S1: Install the measuring support device at a suitable position on the measuring machine according to the shape of the curved glass; Step S2: Place the curved glass on the gear of the support device, ensuring it does not tip over or shift. Step S3: Extract the two positioning pins on the curved glass and their corresponding planes, and construct two intersection points a and b. These two intersection points are located at the two ends of the bottom edge of the curved glass, respectively. Step S4: Construct the symmetrical point c of intersection points a and b, and record the Z-coordinate value of point c; Step S5: Capture data in the data acquisition window of the measurement software. Draw a theoretical intersection line on the digital model. Modify the Z value of this line in the capture window to the Z coordinate value of the symmetrical point c. Generate a slice curve line L. Edit the measurement strategy for this line. Then click to view the number of measurement points window. At this time, you can see the coordinate values ​​of all points and their NX, NY, and NZ values. Select the point e closest to one corner of the triangular glass as the third point. Record the X, Y, and Z coordinate values ​​of point e and its N value. X N Y N Z value; S6. In the measurement program, edit a measuring point and set its X, Y, Z coordinates and N. X N Y N Z The value is the same as that of point e; S7. The X and Y coordinates of point e in the machine coordinate system have been determined. The Z coordinate can be obtained by calculating the difference between the X coordinate value of point e in the digital model and the Z value of the symmetrical point c in the machine coordinate system, shifting the measuring ball of the measuring machine upward, and can be obtained through an automatic positioning measuring machine.

2. A support device for establishing a coordinate system in coordinate measuring machine (CMM) of curved glass, used to implement the coordinate system establishment method for CMM of curved glass as described in claim 1, characterized in that, The measuring machine includes a measuring machine plate (14), one end of which is fixed with two opposing first bases (1) with internal threads, and a worm gear (3) with a scale (8) is connected between the two first bases (1); the other end is fixed with a third base (11), and a track (10) is fixed on the third base (11); a second base (2) is provided between the two first bases (1) and the third base (11), and a shaft (12) is connected on the second base (2). An L-shaped bracket (5) is fitted in the middle of the shaft (12) for installing an adjustable center (4); gears (7) and bearings (9) are connected to the two ends of the shaft (12) respectively; the gears (7) mesh with the worm gear (3), and the gears (7) are used to place curved glass, and the bearings (9) are installed in the track (10).

3. The support device for establishing a coordinate system for coordinate measurement of curved glass as described in claim 2, characterized in that, The two first bases (1), the second base (2) and the third base (11) are all arranged in parallel relative to each other, with the second base (2) located in the middle position between the first base (1) and the third base (11).

4. The support device for establishing a coordinate system for coordinate measurement of curved glass as described in claim 2, characterized in that, The shaft (12) is set parallel to the measuring machine plate (14).

5. The support device for establishing a coordinate system for coordinate measurement of curved glass as described in claim 2, characterized in that, The first base (1) and the second base (2) have the same height.

6. The support device for establishing a coordinate system for coordinate measurement of curved glass as described in claim 2, characterized in that, The gear (7) and bearing (9) are fixed to the shaft (12) by keys with the same limiting direction.

7. The support device for establishing a coordinate system for coordinate measurement of curved glass as described in claim 2, characterized in that, The L-shaped bracket (5) has a matrix of round holes on its vertical surface for mounting adjustable tips (4).

8. The support device for establishing a coordinate system for coordinate measurement of curved glass as described in claim 2, characterized in that, The gear (7) has an angle of 3° per tooth. The upper center line of the gear (7) has an opening with the same thickness as the curved glass (6) and the same depth as the center of the gear. It is engaged with a worm gear with an axial tooth pitch of 3 mm.

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