A machining centering method for a spatial curved surface structure

Abstract

The application provides a machining centering method of a spatial curved surface structure and relates to the technical field of machining. The method is characterized in that: the method is used for quickly positioning through special mark points, the spatial point cloud is introduced into the fitted three-dimensional curved surface model by fitting the three-dimensional curved surface model, the fitting process of the three-dimensional curved surface model is tracked, the final state of the spatial point cloud is consistent with the best fitting state of the three-dimensional curved surface model, the three-dimensional coordinate values of the machining positioning mark points are obtained according to the coordinates of the special mark points in the adjusted spatial point cloud, and then the optimal machining reference is determined through a machine tool to perform machining. Compared with the traditional machine tool marking method, the machining reference determining method is more convenient and faster, the three-dimensional curved surface model is fitted to reach the best state of matching the theoretical numerical model, the spatial point cloud is adjusted, the machining reference is determined by using the coordinates of the special mark points in the adjusted spatial point cloud, and the accuracy is higher.

Description

Technical Field

[0001] This invention relates to the field of mechanical manufacturing technology, and more specifically, to a method for machining and centering a spatial curved surface structure. Background Technology

[0002] For blank products with complex spatial curved surface structures, the main body has a curved shape, making it difficult to detect machining allowances using traditional measurement methods, thus making it impossible to determine the optimal machining datum. For example, the turbine runner in hydropower products is assembled and welded from three castings: the upper crown, the lower ring, and the blades. Among these, the upper crown and lower ring, etc., have a main body that is a flow-through curved surface (such as...). Figure 1 As shown, if the traditional scribing method is used, only the dimensions of one side of the end face can be checked, and most of the remaining dimensions cannot be measured. Before entering the machining process, the machining datum must be determined. The traditional machining centering method is to use a dial indicator on the machine tool, typically marking 8 generatrices on both the inner and outer sides, with 6-8 points on each generatrices. This takes a long time on the machine tool, and even then, machining eccentricity often occurs, resulting in a larger machining volume on one side and a smaller dimension on the opposite side. By the time the operator discovers the problem, some parts have already been machined and cannot be re-marked. For larger upper crowns and lower rings, the current technology, to ensure machining accuracy, involves pre-machining after marking the dial indicator, increasing the number of times the workpiece is lifted, turned, and clamped, before marking the dial indicator again to determine the datum. While this avoids the problem of smaller dimensions, it further increases the machining time. In summary, for large and complex curved surface castings such as upper crowns and lower rings, and other spatial curved surface structure blanks such as irregular forgings, the current methods for scribing and centering during machining are difficult, making it hard to determine the machining datum, and easily leading to problems such as welding repairs or scrap due to eccentricity. Summary of the Invention

[0003] The problem this invention aims to solve is how to quickly and accurately center complex spatial curved surface structures during the processing.

[0004] To address the above problems, this invention provides a method for machining and centering a spatial curved surface structure, comprising:

[0005] Marking points are pasted on the inner and outer surfaces of the spatial curved surface structure. The marking points include positioning base points and special marking points formed by pasting multiple positioning base points into a preset shape.

[0006] A laser camera and Vxelements software were used to collect the marked points on the spatial curved surface structure to obtain a spatial point cloud;

[0007] The inner and outer surfaces of the spatial curved surface structure are scanned using a 3D scanner to obtain a 3D curved surface model. The coordinate system of the 3D curved surface model is the same as the coordinate system of the spatial point cloud.

[0008] fitting the three-dimensional curved surface model, adjusting the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model of the spatial curved surface structure, to obtain a fitted three-dimensional curved surface model;

[0009] importing the spatial point cloud into the fitted three-dimensional curved surface model, adjusting the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional curved surface model, to obtain an adjusted spatial point cloud;

[0010] obtaining the three-dimensional coordinates of the special marker points in the adjusted spatial point cloud;

[0011] obtaining the machining center of the spatial curved surface structure according to the three-dimensional coordinates of the special marker points.

[0012] Preferably, the marker points further include a zero point arranged on the outer surface of the spatial curved surface structure and pasted by a plurality of positioning base points, and the zero point is the coordinate system origin of the spatial point cloud.

[0013] Preferably, the laser camera and Vxelements software are used to collect the marker points on the spatial curved surface structure to obtain a spatial point cloud, including:

[0014] photographing and identifying the marker points pasted on the inner and outer surfaces of the spatial curved surface structure from different angles to obtain a plurality of photos, and each of the photos includes a specified number of marker points at different positions;

[0015] splicing the plurality of photos to obtain the spatial positions of each of the marker points;

[0016] obtaining the spatial point cloud according to the spatial positions of each of the marker points.

[0017] Preferably, the adjusting of the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model of the spatial curved surface structure includes:

[0018] obtaining the machining allowance of each point on the three-dimensional curved surface model;

[0019] translating the coordinate system origin of the three-dimensional curved surface model and / or rotating the coordinate system axis of the three-dimensional curved surface model according to the machining allowance, so that the three-dimensional curved surface model coincides with the coordinate system of the theoretical numerical model; wherein the rotation axis for rotating the coordinate system axis of the three-dimensional curved surface model includes one of the coordinate system axis of the three-dimensional curved surface model and an arbitrarily established coordinate axis.

[0020] Preferably, the adjusting of the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional curved surface model includes:

[0021] acquiring coordinate conversion data used in the process of adjusting the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model;

[0022] adjusting the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional curved surface model according to the coordinate conversion data.

[0023] Preferably, the coordinate conversion data is stored in a file in the tfm format.

[0024] Preferably, the adjusting the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model of the spatial curved surface structure further comprises:

[0025] displaying different colors of the three-dimensional curved surface model according to the size of the machining allowance.

[0026] Preferably, the displaying different colors of the three-dimensional curved surface model according to the size of the machining allowance comprises:

[0027] when the machining allowance exceeds a preset value, the three-dimensional curved surface model displays a first color;

[0028] when the machining allowance is less than the preset value, the three-dimensional curved surface model displays a second color.

[0029] Preferably, the positioning base points are arranged at intervals between the inner and outer surfaces of the spatial curved surface structure, and the distance between every two positioning base points is 150-200 mm.

[0030] Preferably, the three-dimensional laser scanning measurement system comprises a collection device and a Vxelements software, the collection device is used for photographing and identifying the mark points pasted on the inner and outer surfaces of the spatial curved surface structure, and the Vxelements software is used for generating the spatial position coordinates of the mark points.

[0031] The machining centering method of the spatial curved surface structure of the present application has the following advantages compared with the prior art:

[0032] The present application can be quickly positioned by the special mark point method, and the space point cloud is introduced into the three-dimensional curved surface model after fitting by fitting the three-dimensional curved surface model with the theoretical numerical model, the fitting process of the three-dimensional curved surface model is tracked, so that the final state of the space point cloud is consistent with the best fitting state of the three-dimensional curved surface model, and finally the three-dimensional coordinate value of the machining positioning mark point is obtained according to the coordinates of the special mark point in the adjusted space point cloud, and then the optimal machining reference is determined through the machine tool, and machining is carried out. Compared with the traditional machine tool marking table method, the machining reference determination method of the present application is more convenient and fast, and by fitting the three-dimensional curved surface model to the best state matching the theoretical numerical model, and then adjusting the space point cloud, the machining reference is determined by the special mark point coordinates in the adjusted space point cloud, and the accuracy is higher. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The flow chart of the machining centering method of the space curved surface structure in the embodiment of the present application is shown in the figure.

[0034] Figure 2 The schematic diagram of the space point cloud of the lower ring in the embodiment of the present application is shown in the figure.

[0035] Figure 3 The schematic diagram of the space point cloud of the lower ring in the embodiment of the present application is shown in the figure.

[0036] Figure 4 The schematic diagram of the three-dimensional curved surface model of the lower ring in the embodiment of the present application is shown in the figure.

[0037] Figure 5 The schematic diagram of the three-dimensional curved surface model of the lower ring in the embodiment of the present application is shown in the figure.

[0038] Figure 6 The three-dimensional curved surface model of the lower ring in the embodiment of the present application is shown in the figure.

[0039] Figure 7 The three-dimensional curved surface model of the lower ring in the embodiment of the present application is shown in the figure. Figure 1 ;

[0040] Figure 8 The three-dimensional curved surface model of the lower ring in the embodiment of the present application is shown in the figure. Figure 2 ;

[0041] Figure 9 The three-dimensional curved surface model of the lower ring in the embodiment of the present application is shown in the figure. Figure 3 ;

[0042] Figure 10 The schematic diagram of the adjusted space point cloud of the lower ring in the embodiment of the present application is shown in the figure.

[0043] Figure 11A schematic view of a comparison between a theoretical numerical model of a lower ring in an embodiment of the present application and an adjusted spatial point cloud.

[0044] Figure 12 A Figure 11 enlarged view. DETAILED DESCRIPTION

[0045] In order to make the above objectives, features and advantages of the present application more apparent and easy to understand, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] Referring to Figure 1 The machining centering method of a spatial curved surface structure (hereinafter also referred to as machining centering method) of an embodiment of the present application comprises:

[0047] S110, marking points are pasted on the inner and outer surfaces of the spatial curved surface structure, the marking points comprising positioning base points and special marking points pasted in a preset shape from the positioning base points;

[0048] S120, a laser camera and Vxelements software are used to collect the marking points on the spatial curved surface structure to obtain a spatial point cloud;

[0049] S130, a three-dimensional scanner is used to scan the inner and outer surfaces of the spatial curved surface structure to obtain a three-dimensional curved surface model, the coordinate system of the three-dimensional curved surface model being the same as that of the spatial point cloud;

[0050] S140, the three-dimensional curved surface model is fitted, and the coordinate system of the three-dimensional curved surface model is adjusted to coincide with that of the theoretical numerical model of the spatial curved surface structure to obtain a fitted three-dimensional curved surface model;

[0051] S150, the spatial point cloud is imported into the fitted three-dimensional curved surface model, and the coordinate system of the spatial point cloud is adjusted to coincide with that of the fitted three-dimensional curved surface model to obtain an adjusted spatial point cloud;

[0052] S160, three-dimensional coordinates of the special marking points in the adjusted spatial point cloud are obtained;

[0053] S170, the machining center of the spatial curved surface structure is obtained according to the three-dimensional coordinates of the special marking points.

[0054] The embodiment uses three-dimensional detection technology to firstly perform three-dimensional scanning on the blank product of the spatial curved surface structure. The three-dimensional detection technology includes two parts, namely, a Vxelements system and a handheld three-dimensional scanner and a laser photographing device, so as to respectively obtain a spatial point cloud and a three-dimensional curved surface model. Since the spatial point cloud is generated on a computer based on the mark points pasted on the inner and outer surfaces of the spatial curved surface structure, and since the spatial curved surface structure generally has structural characteristics such as a large-area curved surface, if the same mark points are used for marking, the points in the generated spatial point cloud are not easy to one-to-one correspond to the mark points on the physical product. Therefore, in the three-dimensional point cloud creation using the laser photographing device and the Vxelements system, special mark points are pasted on the surface of the product, so that the mark points can be quickly found on the computer or the physical product, and the centering is facilitated. The form of the special mark points is not limited, for example, can be a ring structure formed by a plurality of positioning base points around a positioning base point, or can be a triangle, a pentagram or other regular or irregular shapes. In principle, as long as the shape features are different from a single positioning base point, the special mark points can be used.

[0055] After the three-dimensional curved surface model of the physical product with the mark points is obtained by three-dimensional scanning, the curved shell structure of the three-dimensional curved surface model is fitted with the theoretical numerical model of the spatial curved surface structure, so that the three-dimensional curved surface model reaches an optimal state. The optimal state means that each part of the three-dimensional curved surface model has a machining amount to meet the machining requirements. At this time, the three-dimensional curved surface model of the physical product completely matches the theoretical numerical model, and the origin and coordinate axes of the coordinate systems are coincident. The theoretical numerical model refers to the design model before the spatial curved surface structure is produced and manufactured. It can be understood that the physical product of the spatial curved surface structure is produced and manufactured according to the theoretical numerical model.

[0056] Since the three-dimensional curved surface model is a curved surface, and the spatial point cloud is a collection of a plurality of point coordinates generated by the laser photographing device and the Vxelements system irradiated to the surface of the spatial curved surface structure, and is a spatial model matched with the physical product composed of a large number of points, if the spatial point cloud is fitted with the theoretical numerical model, on the one hand, it is not easy to observe the matching between the points and the surface, and on the other hand, the point clouds have a certain spacing, which easily leads to that some parts have machining amounts and some parts have no machining amounts, causing local missing. Therefore, the embodiment adjusts the three-dimensional curved surface model obtained by scanning the physical product according to the theoretical numerical model by fitting the three-dimensional curved surface model with the theoretical numerical model, so that the state of the three-dimensional curved surface model reaches the optimal state. The advantage of fitting the three-dimensional curved surface model of the physical product is that it is more intuitive, it is more convenient to adjust the optimal state, and all surfaces can be considered to ensure that the machining requirements are met.

[0057] But through the three-dimensional curved surface model can only view the machining allowance of each part, and detect whether the actual model of the physical object can meet the machining, but it cannot realize the centering work during machining. Therefore, the embodiment also tracks the coordinate origin to make the three-dimensional space point cloud reach the same coordinate system as the fitted three-dimensional curved surface model of the physical object, so that each point of the space point cloud falls on the curved surface of the three-dimensional curved surface model. Then, the required special marker points are selected in the adjusted space point cloud, and the new coordinate values of the special marker points are generated in the adjusted coordinate system origin. Subsequently, the machining center is adjusted according to the coordinates of the special marker points.

[0058] The embodiment tracks the fitting process of the three-dimensional curved surface model by the special marker point method, fits the three-dimensional curved surface model and the theoretical model first, and then imports the space point cloud into the fitted three-dimensional curved surface model. The final state of the space point cloud is consistent with the best fitting state of the three-dimensional curved surface model. Finally, the three-dimensional coordinate values of the machining positioning markers are obtained according to the coordinates of the special marker points in the adjusted space point cloud. The machine tool can quickly and conveniently determine the optimal machining reference for machining, and the traditional machine tool marking method is changed.

[0059] In some embodiments, in step S110, the marker points are pasted on the inner and outer surfaces of the space curved surface structure, and the marker points have a certain interval. The interval can be equal or unequal. In the embodiment, the interval is preferably 150-200 mm. The marker point is a special reflective point matched with the three-dimensional laser scanning measurement system and can be recognized by the scanning device of the three-dimensional laser scanning measurement system. Generally, it is a circular sticker with adhesive on the back, and the specifications include Φ6 mm, Φ10 mm, Φ12 mm, etc. The arrangement of the marker points can be set according to the characteristics of the space curved surface structure. In principle, the denser the marker points are set, the closer the space model obtained by scanning is to the actual object and the more accurate it is. Figure 2 The special marker point can have a shape as shown by the circle, and 1, 1, 1, and 3 positioning base points are arranged around the central positioning base point. The position and number of the special marker points can be set according to actual needs and the characteristics of the space curved surface structure.

[0060] Step S110 further includes: setting a zero point pasted by a plurality of positioning base points on the outer surface of the space curved surface structure. The zero point is the coordinate system origin of the space point cloud. When scanning subsequently, each point in the space point cloud is a point cloud formed with the origin.

[0061] In some embodiments, in step S120, the laser camera and Vxelements software are used to collect the marker points on the space curved surface structure to obtain the space point cloud, including:

[0062] The mark points pasted on the inner and outer surfaces of the spatial curved surface structure are photographed and recognized from different angles to obtain multiple photos, and each of the photos includes a specified number of mark points at different positions;

[0063] The multiple photos are spliced to obtain the spatial positions of each mark point;

[0064] The spatial point cloud is obtained according to the spatial positions of each mark point.

[0065] The three-dimensional laser scanning measurement system used in the embodiment includes a collection device for photographing and recognizing the mark points pasted on the inner and outer surfaces of the spatial curved surface structure and a Vxelements software for generating the spatial positions of the mark points.

[0066] The following ring product is taken as an example. Since the lower ring wall is thin, it is difficult to establish the inner and outer surfaces in the same coordinate system. In order to form the inner and outer sides as a whole, the "bridging method" or the "sequential" connection method is used to realize the creation of the whole spatial point cloud. According to the splicing principle of the three-dimensional laser scanning measurement system, four different position code points are selected in each photo, and the multiple photos taken by the three-dimensional laser scanning measurement system are spliced to obtain the spatial positions of each mark point, so as to obtain the spatial point cloud of the whole product, as shown in Figure 3 It can be seen that the coordinate system origin of the spatial point cloud is located on the curved side wall, which is mainly because the coordinate origin is set on the outer surface of the product when the spatial point cloud coordinate system is established, that is, the zero point set on the outer surface of the spatial curved surface structure as described above.

[0067] In some embodiments, in step S130, a three-dimensional scanner is used to scan the inner and outer surfaces of the spatial curved surface structure to obtain a three-dimensional curved surface model of the actual product. The three-dimensional curved surface model of the actual product is taken as an example, as shown in Figure 4 It can be seen that the coordinate system origin of the three-dimensional curved surface model at this time is the same as the coordinate origin of the spatial point cloud, which is mainly because the three-dimensional scanner and the scanning device of the three-dimensional laser scanning measurement system scan the same object, that is, the spatial curved surface structure with mark points, and the outer surface of the spatial curved surface structure is provided with a zero point and coordinate axes to facilitate subsequent scanning by taking the zero point as the coordinate system origin.

[0068] In some embodiments, in step S140, the three-dimensional scanned curved surface of the actual product is fitted with a theoretical numerical model. As shown in Figure 5 It can be seen that the coordinate origin of the three-dimensional theoretical numerical model is located at the center position, while the curved surface origin of the actual product scanning is located on the first boundary. Therefore, when the three-dimensional curved surface model and the theoretical numerical model are imported into the same interface, the following phenomenon will occurFigure 6 Therefore, it is necessary to fit the three-dimensional surface model scanned from the physical object with the theoretical numerical model. It should be noted that the coordinate system origin of the three-dimensional surface model scanned from the physical object and the coordinate system origin of the theoretical numerical model are not necessarily located on the boundary and the center position as shown in the embodiment, but in general, the coordinate system origins of the two are different. Therefore, as long as the coordinate origins of the two are different, the three-dimensional surface model of the physical object needs to be fitted.

[0069] The fitting process mainly takes the three-dimensional theoretical numerical model as the reference object, and the coordinate origin is fixed. The coordinate position of the three-dimensional surface model of the physical object is adjusted so that the three-dimensional model of the physical object wraps the theoretical numerical model, as shown in Figure 7 Specifically, the adjustment of the coordinate system of the three-dimensional surface model to coincide with the coordinate system of the theoretical numerical model of the spatial curved surface structure comprises:

[0070] Obtaining the machining allowance of each point on the three-dimensional surface model;

[0071] According to the machining allowance, the coordinate system origin of the three-dimensional surface model is translated, and / or the coordinate system axis of the three-dimensional surface model is rotated, so that the three-dimensional surface model coincides with the coordinate system of the theoretical numerical model; wherein the rotation axis of the rotation of the coordinate system axis of the three-dimensional surface model comprises one of the coordinate system axis of the three-dimensional surface model and an arbitrarily established coordinate axis.

[0072] In the embodiment, according to the machining allowance of each part of the three-dimensional surface model, it is judged whether the coordinate origin of the three-dimensional surface model needs to be moved. For example, if the machining allowance shows a negative value, it means that the machining allowance is insufficient here, and if it is not adjusted, it may cause the situation of insufficient size during subsequent machining. Therefore, the state of the three-dimensional surface model needs to be adjusted by translation or rotation, so that the three-dimensional surface model coincides with the coordinate system of the theoretical numerical model. It should be noted that the fitting process can be automatically fitted by software or manually fitted. So-called manual fitting means that whether to adjust and how to adjust are determined artificially according to the machining allowance. Exemplarily, the fitting state of the three-dimensional surface model after adjustment with the theoretical numerical model is shown in Figure 8 As can be seen from Figure 8 , there are many insufficient size parts in Figure 9 , and it is not the best fitting state. Therefore, it needs to be continuously adjusted. The adjustment method is still translation or rotation or a combination thereof. The adjustment result is shown in Figure 9 As can be seen from , the depths of all regions in

[0073] are uniform, indicating that there is machining allowance at each part, which can meet the machining requirements.In some embodiments, in step S150, the three-dimensional point cloud is brought into the same coordinate system as the adjusted real three-dimensional model by the coordinate origin tracking method. The adjustment of the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional surface model comprises:

[0074] Obtaining coordinate conversion data used in the process of adjusting the coordinate system of the three-dimensional surface model to coincide with the coordinate system of the theoretical numerical model;

[0075] Adjusting the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional surface model according to the coordinate conversion data.

[0076] Specifically, the adjusted real three-dimensional coordinates are converted into a tfm file using the save command in coordinate conversion, and then the three-dimensional point cloud is imported into the model, and the three-dimensional point cloud coordinates are made consistent with the real three-dimensional model using the load command in coordinate conversion. Before adjustment, as shown in Figure 3 , after adjustment, as shown in Figure 10 , at this time, the point cloud state is consistent with the best fitting state of the three-dimensional surface model of the real object.

[0077] Step S150 further comprises, after adjusting the coordinate system of the spatial point cloud to coincide with the fitted three-dimensional surface model, comparing and analyzing the spatial point cloud model with the theoretical numerical model, as shown in Figure 11 , the surface in the figure represents the theoretical numerical model, and the points on the surface represent the spatial point cloud model. It can be seen that after the fitting of the three-dimensional surface model with the theoretical numerical model and the fitting of the spatial point cloud with the fitted three-dimensional surface model, each point of the spatial point cloud falls on the theoretical numerical model.

[0078] In some embodiments, the adjustment of the coordinate system of the three-dimensional surface model to coincide with the coordinate system of the theoretical numerical model of the spatial surface structure further comprises: displaying the three-dimensional surface model in different colors according to the size of the machining allowance.

[0079] In some embodiments, the displaying of the three-dimensional surface model in different colors according to the size of the machining allowance comprises: when the machining allowance exceeds a preset value, the three-dimensional surface model is displayed in a first color; and when the machining allowance is less than the preset value, the three-dimensional surface model is displayed in a second color. For example, Figure 11 , the different depths of the points indicate different machining allowances.

[0080] Thus, the coordinates of different marker points can be obtained. In this embodiment, special marker points are set to facilitate positioning, so that the three-dimensional coordinates of the special marker points in the adjusted spatial point cloud can be obtained, as shown in Figure 12 , and Figure 12A001 and A002 in the figure represent the labels of different special mark points. After obtaining the three-dimensional coordinates of the special mark points, the machining center of the spatial curved surface structure can be further obtained according to the three-dimensional coordinates of the special mark points. Compared with the traditional direct table setting on the machine tool, the machining centering method of the embodiment can determine the machining reference more quickly, conveniently and accurately.

[0081] In summary, the machining centering method of the embodiment can be applied to the machining centering of almost all complex spatial curved surface structure blank products. Taking the lower ring product in the field of water turbine blades as an example, at least 2 days of table setting time on the machine tool can be saved for each lower ring by using the method of the embodiment. For some complex spatial curved surface structure products, the traditional method cannot be used for measurement. By using the three-dimensional scanning of the embodiment, the best fitting between the actual three-dimensional model and the theoretical numerical model can be realized, the most basic data of casting can be mastered, data support can be provided for the optimization of the hot processing technology, and a foundation can be laid for optimizing the process and reducing the processing amount. For the complex spatial curved surface structure blank, the method for determining the machining reference of the embodiment can optimize the machining, avoid the occurrence of size shortage repair welding due to machining eccentricity, and avoid the generation of waste products.

[0082] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications shall fall within the protection scope of the present disclosure.

Claims

1. A method for processing and centering a spatial curved surface structure, characterized in that, The method comprises the following steps: pasting mark points on the inner and outer surfaces of the spatial curved surface structure, the mark points comprising positioning base points and special mark points pasted in a preset shape by a plurality of positioning base points; collecting the mark points on the spatial curved surface structure by using a three-dimensional laser scanning measurement system to obtain a spatial point cloud; scanning the inner and outer surfaces of the spatial curved surface structure by using a three-dimensional scanner to obtain a three-dimensional curved surface model, the coordinate system of the three-dimensional curved surface model being the same as the coordinate system of the spatial point cloud; fitting the three-dimensional curved surface model to adjust the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of a theoretical numerical model of the spatial curved surface structure to obtain a fitted three-dimensional curved surface model; importing the spatial point cloud into the fitted three-dimensional curved surface model to adjust the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional curved surface model to obtain an adjusted spatial point cloud; obtaining three-dimensional coordinates of the special mark points in the adjusted spatial point cloud; obtaining a machining center of the spatial curved surface structure according to the three-dimensional coordinates of the special mark points.

2. The machining centering method of a spatial curved surface structure according to claim 1, characterized in that, The mark points further comprise zero points provided on the outer surface of the spatial curved surface structure and pasted by a plurality of positioning base points, the zero points being the coordinate system origin of the spatial point cloud.

3. The method of claim 1, wherein The method of collecting the mark points on the spatial curved surface structure by using a three-dimensional laser scanning measurement system to obtain a spatial point cloud comprises the following steps: photographing and identifying the mark points pasted on the inner and outer surfaces of the spatial curved surface structure from different angles to obtain a plurality of photos, and each photo comprises a specified number of mark points at different positions; splicing the plurality of photos to obtain the spatial positions of each mark point; obtaining the spatial point cloud according to the spatial positions of each mark point.

4. The method of claim 1, wherein The method of adjusting the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model of the spatial curved surface structure comprises the following steps: obtaining machining allowances of each point on the three-dimensional curved surface model; performing translation on the coordinate system origin of the three-dimensional curved surface model and / or performing rotation on the coordinate system axis of the three-dimensional curved surface model according to the machining allowances to make the three-dimensional curved surface model coincide with the coordinate system of the theoretical numerical model; wherein the rotation axis for performing rotation on the coordinate system axis of the three-dimensional curved surface model comprises one of the coordinate system axis of the three-dimensional curved surface model and an arbitrarily established coordinate axis.

5. The method of claim 1, wherein The method of adjusting the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional curved surface model comprises the following steps: obtaining coordinate conversion data used in the process of adjusting the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model; adjusting the coordinate system of the spatial point cloud to coincide with the coordinate system of the fitted three-dimensional curved surface model according to the coordinate conversion data.

6. The method of claim 5, wherein the method further comprises: The coordinate conversion data is stored in a file in a tfm format.

7. The method of claim 4, wherein the method further comprises: The method of adjusting the coordinate system of the three-dimensional curved surface model to coincide with the coordinate system of the theoretical numerical model of the spatial curved surface structure further comprises the following steps: displaying the three-dimensional curved surface model in different colors according to the size of the machining allowances.

8. The method of claim 7, wherein the method further comprises: The method of displaying the three-dimensional curved surface model in different colors according to the size of the machining allowances comprises the following steps: When the machining allowance exceeds a preset value, the three-dimensional curved surface model displays a first color; When the machining allowance is less than the preset value, the three-dimensional curved surface model displays a second color.

9. The method of claim 1, wherein The positioning base points are arranged at intervals between the inner and outer surfaces of the spatial curved surface structure, and the interval between every two positioning base points is 150-200 mm.

10. The machining centering method for a spatial curved surface structure according to claim 1, characterized in that, The three-dimensional laser scanning measurement system comprises a collection device and Vxelements software, the collection device is used for photographing and identifying the mark points pasted on the inner and outer surfaces of the spatial curved surface structure, and the Vxelements software is used for generating the spatial position coordinates of the mark points.

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