Method for measuring large component of steel bridge

Abstract

The invention discloses a method for measuring a large component of a steel bridge, and belongs to the technical field of steel bridge component machining and manufacturing. The method comprises the following steps: (1) constructing a measuring field; (2) establishing a three-dimensional rectangular coordinate system; (3) setting geometric feature points; (4) setting positioning feature points; (5) setting measuring points; (6) scanning a bolt hole group; (7) coordinate transformation; and (8) calculating production errors. The method is suitable for three-dimensional measurement and modeling of the large steel member, the advantages of different measurement devices are fully utilized, the advantages of the different measurement devices are made the best of one another, the measurement method is high in practicability, easy to operate and high in efficiency, the geometric dimension precision and the bolt hole position precision of the steel bridge member can be guaranteed, and the manufacturing quality of the steel bridge member can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel bridge component processing and manufacturing, and in particular relates to a measuring method for large steel bridge components. Background Art

[0002] With the continuous development of measurement technology, 3D laser scanner measurement, photogrammetry and 3D laser tracking measurement instruments have emerged in the field of steel bridge manufacturing. However, in the process of measuring large components, handheld 3D laser scanners have disadvantages such as low measurement efficiency, low long-distance measurement accuracy and large storage data. Although photogrammetry has greater accuracy, it also has the disadvantage of low measurement efficiency, which is not conducive to promotion and application. Although the measurement of 3D laser tracking measurement instruments is more accurate, it has higher requirements for the use environment and is difficult to apply in workshops and other environments.

[0003] Steel bridge components have the characteristics of large outline dimensions and high production precision requirements. Their geometric precision requirements are ≤2mm, and the hole group measurement precision requirements are ≤1mm. The above three-dimensional measurement technologies are difficult to take into account the requirements of measurement efficiency and measurement accuracy at the same time. In order to ensure the measurement accuracy and efficiency of large-sized steel bridge members, it is urgent to develop a measurement technology suitable for large steel bridge components based on the existing three-dimensional measurement technology. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention designs a measurement method for large steel bridge components. The total station and the handheld 3D scanner each take advantage of their strengths to effectively ensure the measurement accuracy of the steel bridge components (accuracy ≤ 1mm), and construct a real 3D wireframe model based on the measurement data, which is convenient for rapid calculation of errors. The method is highly practical, simple to operate and highly efficient, and has been proven to be effective in practice.

[0005] The present invention provides a method for measuring large steel bridge components, which is characterized by comprising the following steps: ① Place the steel component on a stable support, the height of which is not less than the tripod height of the total station; ② Set three coordinate points around the steel component, and the three coordinate points and the plumb bob direction constitute a three-dimensional rectangular coordinate system; ③ Set several geometric inflection points and connection points on the surface of the steel component as geometric feature points; ④ Set three positioning feature points for each bolt hole group of the steel component, and the three positioning feature points constitute a plane rectangular coordinate system; ⑤ According to the distribution of the geometric feature points and the positioning feature points, set several measuring points around the steel component, and the total station is sequentially set up on the measuring points to measure all the geometric feature points and the positioning feature points. ⑥ Use a handheld scanner to scan and measure the bolt hole positions in each bolt hole group of the steel component to obtain the two-dimensional coordinate data of all the bolt hole positions in the corresponding plane rectangular coordinate system; ⑦ Based on the three positioning feature points of each bolt hole group, convert the two-dimensional coordinate data of all the bolt hole positions in the corresponding plane rectangular coordinate system into three-dimensional coordinate data in the three-dimensional rectangular coordinate system; ⑧ Compare the three-dimensional coordinate data of the steel component with the theoretical coordinate data to obtain the production error.

[0006] Furthermore, a wireframe model of the steel component is established on the drawing software according to the three-dimensional coordinate data of the geometric feature points and the positioning feature points in the three-dimensional rectangular coordinate system, and a wireframe model of each bolt hole group is established on the drawing software according to the two-dimensional coordinate data of the bolt hole positions in the corresponding plane rectangular coordinate system, and based on the three positioning feature points of the bolt hole group, the wireframe model of each bolt hole group is fitted with the wireframe model of the steel component to form a real three-dimensional wireframe model of the steel component.

[0007] Furthermore, the production error between the real three-dimensional wireframe model and the theoretical geometric model of the steel member is obtained using drawing software.

[0008] Compared with the prior art, the outstanding effects of the present invention are: ① fully utilizing the characteristics of the total station's long-distance measurement and high accuracy (accuracy of 0.5mm within a range of 100m) and the handheld 3D scanner's high short-range measurement accuracy (accuracy of 0.5mm within a range of 1.5m), taking advantage of each to improve measurement efficiency while ensuring measurement accuracy; ② constructing a real 3D wireframe model to facilitate the rapid calculation of steel component processing errors and simulate pre-assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of the measurement site and the bracket of this embodiment; Figure 2 is a schematic diagram of a three-dimensional rectangular coordinate system of this embodiment; Figure 3is a schematic diagram of geometric feature points and positioning feature points in this embodiment; Figure 4 is a schematic diagram of the bolt hole group and the plane rectangular coordinate system of this embodiment; Figure 5 Schematic diagram of the measurement points in this embodiment. DETAILED DESCRIPTION

[0010] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0011] Step 1: Set up the measurement site. Figure 1 As shown, the steel component is placed on a stable bracket 1 to ensure that the steel component does not move or shake during the measurement process. At the same time, in order to facilitate the measurement of the total station, the height of the bracket 1 is not less than the height of the tripod of the total station.

[0012] Step 2: Establish a three-dimensional rectangular coordinate system. Figure 2 As shown, three coordinate points 2 are set around the steel member, and the three coordinate points 2 and the plumb bob direction form a three-dimensional rectangular coordinate system 20. For ease of calculation, the coordinate axes of the three-dimensional rectangular coordinate system 20 are parallel or perpendicular to the main contour line of the steel member.

[0013] Step 3: Set up geometric feature points. Figure 3 As shown, the geometric inflection points on the surface of the steel component that determine its structure and the two end points of the connection lines of different components are set as geometric feature points 3-1, and these geometric feature points 3-1 can outline the wireframe model of the steel component; Step 4: Set up positioning feature points. Figure 3 As shown, in order to establish the positional relationship of each bolt hole group on the steel component, this embodiment sets three positioning feature points 3-2 for each bolt hole group, and these positioning feature points 3-2 can determine the precise position of the corresponding bolt hole group on the steel component. Figure 4 As shown, the above three positioning feature points 3 - 2 constitute a plane rectangular coordinate system 30 . For the convenience of calculation, the coordinate axes of the plane rectangular coordinate system 30 are parallel or perpendicular to the contour lines of the adjacent steel components.

[0014] Step 5: Set up measurement points. Figure 5 As shown, according to the distribution of all the above-mentioned geometric feature points 3-1 and positioning feature points 3-2, several measuring points 4 are set around the steel structure, and it is required that when the total station is set up on the set measuring points 4 in sequence, all the geometric feature points 3-1 and positioning feature points 3-2 can be measured to obtain the three-dimensional coordinate data of all the geometric feature points 3-1 and positioning feature points 3-2 in the three-dimensional rectangular coordinate system 20.

[0015] Step 6: Establishing a wireframe model of the steel component. Establishing a wireframe model of the steel component on the drawing software according to the three-dimensional coordinate data of the geometric feature point 3 - 1 and the positioning feature point 3 - 2 in the three-dimensional rectangular coordinate system 20 .

[0016] Step 7: Scan the bolt hole group. Use a handheld scanner to scan and measure the bolt hole positions in each bolt hole group of the steel component to obtain the two-dimensional coordinate data of all the bolt hole positions in the corresponding plane rectangular coordinate system 30.

[0017] Step 8: Establishing a wireframe model of the bolt hole group. Establishing a wireframe model of each bolt hole group on the drawing software according to the two-dimensional coordinate data of the bolt hole position in the plane rectangular coordinate system 30 .

[0018] Step 9: Wireframe fitting. Based on the three positioning feature points 3-2 of each bolt hole group, the two-dimensional coordinate data of all bolt hole positions in the corresponding plane rectangular coordinate system 30 are converted into three-dimensional coordinate data in the three-dimensional rectangular coordinate system 20, and the wireframe model of the bolt hole group is fitted with the wireframe model of the steel component to form a real three-dimensional wireframe model of the steel component.

[0019] Step 10: Calculate the error. Use drawing software to calculate the production error between the real 3D wireframe model and the theoretical geometric model of the steel component to complete the quality inspection of the steel component.

Claims

1. A method for measuring large steel bridge components, characterized in that: The following steps are included: ① Place the steel structure on a stable support (1), wherein the height of the support (1) is not less than the height of the tripod of the total station; ② setting three coordinate points (2) around the steel component, wherein the three coordinate points (2) and the plumb bob direction form a three-dimensional rectangular coordinate system (20); ③ Set several geometric inflection points and connection points on the surface of the steel component as geometric feature points (3-1); ④ setting three positioning feature points (3-2) for each bolt hole group of the steel component, wherein the three positioning feature points (3-2) constitute a plane rectangular coordinate system (30); ⑤ According to the distribution of the geometric feature points (3-1) and the positioning feature points (3-2), a plurality of measuring points (4) are set up around the steel member, and a total station is sequentially set up on the measuring points (4) to measure all the geometric feature points (3-1) and the positioning feature points (3-2), thereby obtaining three-dimensional coordinate data of all the geometric feature points (3-1) and the positioning feature points (3-2) in the three-dimensional rectangular coordinate system (20); ⑥ Using a handheld scanner to scan and measure the bolt hole positions in each bolt hole group of the steel component to obtain two-dimensional coordinate data of all bolt hole positions in the corresponding plane rectangular coordinate system (30); ⑦ Taking the three positioning feature points (3-2) of each bolt hole group as a reference, converting the two-dimensional coordinate data of all bolt hole positions in the corresponding plane rectangular coordinate system (30) into three-dimensional coordinate data in the three-dimensional rectangular coordinate system (20); ⑧Compare the three-dimensional coordinate data of the steel component with the theoretical coordinate data to obtain the production error.

2. The measuring method according to claim 1, characterized in that: A wireframe model of the steel component is established on the drawing software according to the three-dimensional coordinate data of the geometric feature points (3-1) and the positioning feature points (3-2) in the three-dimensional rectangular coordinate system (20); a wireframe model of each bolt hole group is established on the drawing software according to the two-dimensional coordinate data of the bolt hole positions in the corresponding plane rectangular coordinate system (30); and based on the three positioning feature points (3-2) of the bolt hole group, the wireframe model of each bolt hole group is fitted with the wireframe model of the steel component to form a real three-dimensional wireframe model of the steel component.

3. The measuring method according to claim 2, characterized in that: The production error of the real three-dimensional wireframe model and the theoretical geometric model of the steel member is obtained using drawing software.

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