Method for assembling tail shield of shield machine
By using total station measurements and jack adjustments, combined with process support and welding control, the problem of poor installation accuracy of various parts of the tail shield was solved, thus improving the quality of tunnel boring machine construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-23
- Publication Date
- 2026-03-17
AI Technical Summary
Poor installation accuracy of different parts of the tail shield affects the quality of shield tunneling.
The radius of each segment of the shield tail was measured and recorded using a total station. The center axis and 180° position line of the front and middle shields were calibrated. The position of the segments was adjusted by jacks to ensure accurate alignment and welding of each segment. The stress on the weld was controlled by process supports and welding sequence. Real-time detection and correction were carried out to ensure that the roundness met the design requirements.
It improved the assembly accuracy and efficiency of the tail shield of the tunnel boring machine, ensured the stress strength of the weld and the overall roundness of the tail shield, and improved the quality of tunnel construction.
Smart Images
Figure CN116160158B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of tunnel boring machine (TBM) installation technology, specifically to a method for assembling the tail shield of a TBM. Background Technology
[0002] A tunnel boring machine (TBM) is a type of tunnel excavator that uses the shield tunneling method for tunneling. It is cylindrical in shape and consists of three parts: the front shield, the middle shield, and the tail shield. The front shield is installed behind the cutterhead and contains a steel structure supporting the main drive unit and the screw conveyor. The middle shield is securely connected to the front shield via high-strength bolts and welding. The propulsion cylinders for tunneling and the shield articulation cylinders (an auxiliary device for the tail shield) are located within the middle shield area. Supports connected to suspension trusses are mounted on the middle shield for installing the segment assembler. The tail shield is connected to the middle shield via articulation cylinders. Under the protection of the tail shield, the segment assembler assembles the tunnel segments. A sealing brush at the end of the tail shield seals the gaps between the tail shield and the ring of tunnel segments, and grouting pipes within the tail shield fill these gaps with grout.
[0003] Because the tail shield has a large diameter, it is difficult to process it as a whole. It needs to be manufactured in sections. Based on the distribution of the sections, the tail shield is generally divided into bottom shield, left shield, right shield, and top shield. Since the tail shield is a cylindrical structure assembled from various sections, and the roundness of the tail shield has high requirements for the quality of tunnel construction, the assembly accuracy of each section directly affects the final construction quality of the tunnel. Therefore, it is necessary to avoid problems such as misalignment and twisting during the installation of the tail shield sections to ensure the roundness of the tail shield.
[0004] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0005] In view of at least one of the above technical problems, this application provides a method for assembling the tail shield of a tunnel boring machine, which aims to solve the problem of poor installation accuracy of various parts of the tail shield, affecting the quality of tunnel boring machine construction.
[0006] According to one aspect of this disclosure, a method for assembling a tail shield of a tunnel boring machine is provided. The tail shield includes a bottom block, a left side block, a right side block, and a top block, comprising the following steps:
[0007] (1) Before the tail shield is hoisted and lowered into the well, the radius of each section of the tail shield is measured and recorded using a total station;
[0008] (2) Install the bottom block, mark the center axis of the front and middle shields and the 180° position line, and mark the 180° position line on the reaction frame; lift the bottom block into the well, and adjust the position of the bottom block by using the jacks set at the corresponding connection positions of the tail shield and the middle shield and at the bottom of the shield body until the 180° position line of the tail shield coincides with the 180° position line of the front and middle shields, and the straight deviation is less than 3mm; measure the inner diameter of the tail of the bottom block and adjust its tolerance to ±10mm;
[0009] (3) The left side is installed by using a crane and a hand hoist to lift the left side section down into the well to the position to be assembled. The dimensional tolerance is adjusted to -10 to 0 mm by using jacks installed at the corresponding connection between the middle shield and the tail shield. The section is then positioned and welded in place. The radius is measured and the data is recorded.
[0010] (4) Right side section installation: The right side section is lifted down into the well by a crane and a hand hoist to the position to be assembled. The dimensional tolerance is adjusted to -10 to 0 mm by jacks installed at the corresponding connection between the middle shield and the tail shield. The section is then positioned and welded in place. The radius is measured and the data is recorded.
[0011] (5) The top section is installed in a triangular arrangement of lifting lugs, and the two front lifting lugs are equipped with shackles. After being lifted into the well, the size tolerance is adjusted to 0 to +10 mm by jacks installed at the corresponding connection points of the middle shield and the tail shield. Then, it is fixed by positioning and welding, and its radius is measured and the data is recorded.
[0012] (6) Use a total station to verify and adjust the tail shield's tail radius tolerance to ±10mm;
[0013] (7) Install process supports at the segmentation points of the tail shield and at the weld seams between the tail shield and the middle shield;
[0014] (8) Weld each section of the shield tail. First, weld the inner side of each weld, then clean the outer side, and then weld the outer side. Weld the welds that are 180° apart in the four welds symmetrically. Weld each weld in sections.
[0015] (9) Welding process and shell diameter detection after welding: The shell diameter is detected and recorded before formal welding, 15 minutes after welding on one side, 15 minutes after welding on the other side, and after the overall welding is completed. If the shell radius exceeds the size requirements, the shell is mechanically corrected according to the measurement data.
[0016] (10) Weld the circumferential weld between the tail shield and the middle shield. First weld the longitudinal weld, and then weld the transverse weld that is parallel to the shield axis.
[0017] (11) Verify the radius of the tail shield shell. Verify and adjust the dimensions according to the measurement data and the required dimensions of the shell radius, and remove the process support.
[0018] (12) Welding of shield tail brushes: Before welding, grind the weld seam and both sides to reveal a metallic luster. Various shield tail brushes are arranged in a staggered manner from front to back.
[0019] In some embodiments of this disclosure, in step (1), the shield tail is assembled as a whole on the wellhead and its radius is measured and recorded. The measurement positions are 24 points that are evenly divided into the circumferences at the front and rear ends of the radial direction.
[0020] In some embodiments of this disclosure, in step (1), the 0° or 180° center crosshair position line corresponding to the corresponding block is checked, and if there is no line, the corresponding line is marked.
[0021] In some embodiments of this disclosure, in step (2), before hoisting, the welding positions of each section and 50mm on both sides need to be ground until they have a metallic luster.
[0022] In some embodiments of this disclosure, in step (2), the jack includes a vertical adjustment jack and a horizontal adjustment jack. The vertical adjustment jack is located at the edge of the tail shield corresponding to the middle shield and abuts against the corresponding wall of the L-shaped limiting plate fixed at the corresponding edge of the middle shield. The horizontal adjustment jack is vertically located at the corresponding positions on both sides and the center of the outer wall of the tail shield.
[0023] In some embodiments of this disclosure, in steps (3), (4) or (5), one end of the jack rests against the edge of the tail shield, and the other end rests against the corresponding wall of the L-shaped limiting plate fixed at the corresponding edge of the middle shield.
[0024] In some embodiments of this disclosure, in steps (3), (4) or (5), the welding material used for the positioning welding is the same as the preheating temperature and welding material used for the formal welding, and its length is greater than 100 mm.
[0025] In some embodiments of this disclosure, in step (7), the process support is a U-shaped rib.
[0026] In some embodiments of this disclosure, in step (9), the detection point for the shell diameter detection is the intersection of the cross section divided into three equal layers along the axial direction and the shield body.
[0027] In some embodiments of this disclosure, in step (9) or (11), the correction is performed mechanically or by flame correction via a chain or oxyacetylene, and is measured in real time during the correction process.
[0028] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:
[0029] By adjusting each jack and limiting the tolerances, the assembly accuracy and efficiency were effectively improved. Furthermore, by adjusting the welding sequence and real-time adjustments during the welding process, the stress strength of the weld and the overall roundness of the tail shield after welding were ensured. Attached Figure Description
[0030] Figure 1 This is a schematic diagram showing the adjustment of the connection position between the bottom tail shield and the middle shield in one embodiment of this application.
[0031] Figure 2 This is a schematic diagram of the tail shield bottom block adjustment state in one embodiment of this application.
[0032] In the above diagrams, 1 is the tail shield, 2 is the middle shield, 3 is the L-shaped limit plate, 4 is the vertical adjustment jack, and 5 is the horizontal adjustment jack. Detailed Implementation
[0033] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0034] This example discloses a method for assembling the tail shield of a tunnel boring machine. The tail shield includes a bottom section, a left section, a right section, and a top section. It is lowered into the shaft using a 650T crawler crane. The method includes the following steps:
[0035] (1) Before the tail shield is hoisted and lowered into the well, the radius of each section of the tail shield is measured and recorded using a total station.
[0036] Each segment of the tail shield undergoes a certain amount of quality inspection before leaving the factory to ensure that its radius dimensions meet the design requirements. However, considering that the condition of the tail shield during loading, unloading, and transportation cannot be fully controlled, a total station is needed to verify and record the dimensions and radii of each segment when the tail shield arrives at the construction site. This verification checks for errors between the processed radius and the design radius, as well as whether external forces caused deformation during transportation. Accurate recording of the measurement data is used to compare the differences between the radius inspection data before hoisting and the data during assembly in the subsequent assembly process. This helps to monitor errors generated during assembly and provides accurate measurement data for fine-tuning each segment.
[0037] In addition, each segment of the tail shield is marked with a 0° or 180° center crosshair at the center of the corresponding top and bottom blocks before leaving the factory. This is to ensure that the placement of the shield shell during tail shield assembly is on the same axis as the center of the launching platform, which facilitates the installation of the tail shield on the launching platform. To avoid wear and tear during transportation or failure to mark before leaving the factory, the 0° or 180° center crosshair of the corresponding segments is checked before the tail shield is lifted and assembled. If it is blurry and difficult to identify or was not marked before leaving the factory, a total station is used to measure and mark the lines.
[0038] In some other embodiments, if the ground space allows, the tail shield is trial-assembled to verify whether the roundness of the overall assembly meets the requirements. The radius and roundness of the tail shield are detected and recorded by detecting 24 points equally divided at the front and rear ends of the radial circumference.
[0039] (2) Install the bottom block, mark the center axis of the front and middle shields and the 180° position line, and mark the 180° position line on the reaction frame; lift the bottom block into the well, and adjust the position of the bottom block by using jacks set at the corresponding connection positions of the tail shield and the middle shield and at the bottom of the shield body until the 180° position line of the tail shield coincides with the 180° position line of the front and middle shields, and the straight deviation is less than 3mm; use a total station to detect the inner diameter of the tail of the bottom block, and adjust its tolerance to ±10mm by using jacks.
[0040] After verifying each segment of the tail shield and confirming its design requirements, the hoisting and lowering operation can begin. Since the tail shield is being hoisted from the ground downhole, and the bottom block is located at the bottom of the shaft, the bottom segment is installed first. Before installing the bottom segment, the centerline and 180° position line of the front and middle shields are measured and marked. Because the positioning centerline of the underground shield launching platform must coincide with the centerline of the tail shield, the centerline of the front and middle shields, measured using a total station, is calculated and laid out to the reaction frame, clearly marked, serving as a reference benchmark for the positioning and installation of the tail shield bottom segment, ensuring that the centerline of the tail shield coincides with the centerline of the front and middle shields. Simultaneously, it is also necessary to ensure that the 180° position line of the tail shield coincides with the 180° position line of the front and middle shields, with a straight-line deviation of less than 3mm, thereby achieving accurate alignment of the tail shield bottom segment.
[0041] For the radius measurement of the tail shield segment, in this embodiment, a total station is used to observe the assembled front and middle shield bodies, and the shield machine axis is fitted and calculated. The axis is then projected vertically downwards onto the shells of the middle and tail shields, and a mark is painted on the shells. At least three measuring points are selected on the segment arc, and the radius difference between the measuring point positions is calculated based on the fitted shield machine axis and the design radius of the tail shield. The difference between the measured radius and the design radius is obtained, and this is used as the basis for correction.
[0042] During the alignment and installation, the tunnel boring machine (TBM) determines its installation tolerance based on its design using finite element analysis. This tolerance is the allowable deviation that will not affect the smooth excavation of the TBM. In this embodiment, the inner diameter of the tail block is measured and recorded using a total station to ensure a tolerance of ±10mm. If this is not met, adjustments are required. When the tolerance deviation is large, the tail shield base block is re-lifted by a crane, its installation position is changed, and it is re-installed and positioned to correct the deviation. When the tolerance deviation is small, adjustments are made using jacks temporarily installed around the tail shield. In this embodiment, the jacks include vertical adjustment jacks and horizontal adjustment jacks, as detailed below. Figure 1A vertical jack is positioned at the edge of the tail shield corresponding to the connecting middle shield, and rests against the corresponding wall of the L-shaped limiting plate fixed at the edge of the middle shield. The jack's lifting action allows for fine-tuning of the base radius near this position. Considering that the tail shield may deform if the lifting force exceeds the compressive yield strength of the steel during the lifting process, instruments must be used to monitor the adjustment data to prevent the data from exceeding allowable tolerances. (See also...) Figure 2 Horizontal adjustment jacks are vertically installed on both sides and at the center of the outer wall of the tail shield. By lifting the jacks on both sides, the bottom block can be moved to that side, and the position of the bottom block can be adjusted along the circumferential direction. The height of the bottom block of the shield can also be adjusted by raising and lowering each jack.
[0043] In addition, before hoisting, the welding positions of each section and 50mm on both sides must be ground until they have a metallic luster, and the paint, rust, burrs, etc. at the weld seams must be cleaned to avoid affecting the welding quality.
[0044] (3) The left side is installed by using a crane and a hand hoist to lift the left side section down into the well to the position to be assembled. The dimensional tolerance is adjusted to -10 to 0 mm by using jacks installed at the corresponding connection points of the middle shield and the tail shield. The section is then positioned and welded. The radius is measured and the data is recorded by a total station.
[0045] After the tail shield bottom block is installed, the two side blocks are lifted and lowered into the well. In this embodiment, the left side block is installed first. In other embodiments, the right side block is installed first, and then the left side block is installed.
[0046] In this example, three lifting points are set up on the left side block. Each lifting point is equipped with a 20T hand-operated hoist connected to the crane hook by a wire rope. The position of the side block is adjusted by the hand-operated hoist for initial alignment. After the side block is lowered to the position to be spliced, the dimensional tolerance of the side block is further adjusted to -10 to 0 mm by a jack set at the connection between the middle shield and the tail shield. One end of the jack rests against the left side block of the tail shield, and the other end rests against the L-shaped limiting plate welded to the edge of the middle shield and the plate wall parallel to the centerline of the tail shield.
[0047] Furthermore, in this embodiment, considering that the tail shield has already been bent inward during manufacturing, and due to the influence of elastic deformation, it is difficult to continue bending inward. Therefore, during assembly and fine-tuning, it is easier to adjust to a positive value (to the outward expansion value of the shield body) and more difficult to adjust to a negative value (to the inward contraction value of the shield body). That is, it is less difficult to expand outward during the adjustment process than to contract inward. As the left and right blocks are affected by gravity, the force expands outward during installation. To counteract the displacement caused by the expansion force, the left side block is adjusted to a 270° position close to the minimum negative tolerance when lowering it into the well.
[0048] After the left-side section is adjusted into place, it is fixed by tack welding. The welding materials used for tack welding must be the same as those used for the final welding, and the preheating temperature before welding must be consistent with that of the final welding. The length of the tack weld should not be less than 100mm to ensure the reliability of the weld. Before and after welding, to avoid uneven stress or collisions during hoisting, or changes in the section radius caused by thermal expansion and contraction of the tack weld, a total station is used to verify and record the section radius and other data.
[0049] (4) Similarly, the right side section is installed by lifting the right side section down the well to the position to be assembled using a crane and a hand hoist. The dimensional tolerance is adjusted to -10 to 0 mm by using jacks installed at the corresponding connection points of the middle shield and the tail shield, and then the section is positioned and welded. The radius is measured and the data is recorded using a total station.
[0050] (5) The top section is installed in a triangular arrangement of lifting lugs, and the two front lifting lugs are equipped with shackles. After being lifted into the well, the size tolerance is adjusted to 0 to +10 mm by jacks installed at the corresponding connection points of the middle shield and the tail shield. Then, the section is positioned and welded in place. The radius is measured and the data is recorded by a total station.
[0051] Finally, the top section is installed. Since the top section contains grouting pipes and grease pipes that need to connect to the central shield, in this embodiment, to facilitate the insertion of these pipes into the central shield, a 50T shackle is added to each of the two lifting lugs closest to the central shield in the triangular distribution at the top of the top section, causing the top section to tilt towards the front. After initial alignment, the position is fine-tuned using jacks installed at the connection between the central and tail shields. Considering the influence of gravity on the top section, the force during installation causes it to contract inwards. To counteract this inward displacement, the 0° center position of the top section is moved close to the maximum positive tolerance. Before adjustment and after positioning welding, the section radius is checked again to avoid installation and welding errors.
[0052] (6) Use a total station to check and adjust the tail shield's tail radius tolerance to ±10mm.
[0053] After all the sections of the tail shield are assembled, a total station is used to check the radius tolerance of the tail shield to determine whether it meets the tolerance requirement of ±10mm, and corrections are made accordingly based on the measurement data.
[0054] (7) Add process support at the segmentation of the tail shield and at the weld between the tail shield and the middle shield.
[0055] Considering that each segment of the tail shield weighs up to tens of tons, in order to ensure the reliability of the support at the adjacent segments and the corresponding welding positions of the tail shield and the middle shield, and to ensure that the welds can be accurately connected, in this embodiment, a U-shaped stiffener is added at the weld as a process support. It is connected to the tail shield by fillet weld, and the welding size is 20mm.
[0056] (8) Weld each section of the shield tail. First, weld the inner side of each weld, then clean the outer side, and then weld the outer side. Weld the welds that are 180° apart in the four welds symmetrically. Weld each weld in sections.
[0057] (9) Welding process and shell diameter detection after welding: The shell diameter is detected and recorded before formal welding, 15 minutes after welding on one side, 15 minutes after welding on the other side, and after the overall welding is completed. If the shell radius exceeds the size requirements, the shell is corrected according to the measurement data.
[0058] Because welding alters the stress distribution between different sections, and thermal expansion and contraction can cause deformation of the shield, the shell diameter needs to be measured during and before / after welding. In this embodiment, three sections parallel to the shield axis are selected to divide the tail shield's circular surface into three equal parts, and their intersections with the circumference are used as measuring points to reflect changes in the shell diameter. Correction is then performed based on the measurement data to meet design requirements. In this embodiment, mechanical or flame correction is performed using a guide chain or oxy-acetylene torch, and the changes in the tail shield shell are measured in real time during the correction process.
[0059] (10) Weld the circumferential weld between the tail shield and the middle shield. First weld the longitudinal weld, then weld the transverse weld that is parallel to the shield axis.
[0060] Because the tail shield has protruding grouting blocks, some of which extend into the tail of the middle shield, during the formal welding, there are transverse seams parallel to the shield axis and longitudinal seams that coincide with or are parallel to the joints of the middle and tail shields. In this example, considering the influence of gravity, the longitudinal seams are subjected to greater stress than the transverse seams. Therefore, it is chosen to weld the longitudinal seams first, followed by the transverse seams, to control deformation.
[0061] (11) Verify the radius of the tail shield shell. Verify and adjust the dimensions according to the measurement data and the required dimensions of the shell radius, and cut off the process support.
[0062] When cutting off the process support, a root of more than 5mm must be left to prevent damage to the shield body. After cutting, the root is removed by carbon arc gouging, and finally the transition is smoothed by grinding with a grinding wheel.
[0063] (12) Welding of shield tail brushes: Before welding, grind the weld seam and both sides to reveal a metallic luster. Various shield tail brushes are arranged in a staggered manner from front to back.
[0064] In this embodiment, before welding the tail shield brushes, debris, water, oil, and other contaminants inside the tail shield are cleaned, and the weld seam and 20mm on both sides are ground until a metallic luster appears. The tail shield brushes are divided into three types, and when installed, they are arranged from front to back as follows: two A-type brushes, two B-type brushes, and one C-type brush, with staggered seams.
[0065] Although some preferred embodiments of this invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.
[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention is also intended to include these modifications and variations.
Claims
1. A method of assembling a tail shield of a tunneling machine, the tail shield comprising a bottom segment, a left segment, a right segment, a top segment, characterized in that, The method comprises the following steps: (1) Before hoisting the tail shield downhole, a total station instrument is used to measure the radius of each segment of the tail shield and record the measurement; (2) The bottom segment is installed, the central axis of the front and middle shields is calibrated, and the 180° position line is drawn and marked on the reaction frame. The bottom segment is hoisted downhole, and the position of the bottom segment is adjusted to the 180° position line of the tail shield and the 180° position line of the front and middle shields by using the jacks arranged at the corresponding connection positions of the tail shield and the middle shield and at the bottom of the shield body, so that the 180° position line of the tail shield coincides with the 180° position line of the front and middle shields, and the straightness deviation is less than 3 mm. The inner diameter of the tail of the bottom segment is measured, and the tolerance is adjusted to ±10 mm. The jacks comprise vertical adjustment jacks and horizontal adjustment jacks. The vertical jacks are arranged at the edges of the tail shield corresponding to the connection of the middle shield, and abut against the corresponding walls of the L-shaped limiting plates fixed at the corresponding edges of the middle shield. The horizontal adjustment jacks are vertically arranged at the corresponding positions on both sides and in the center of the outer wall of the tail shield; (3) The left segment is installed. The left segment is hoisted downhole to the position to be assembled by using a crane and a hand-operated hoist, and is fixed by positioning and welding after the size tolerance is adjusted to -10-0 mm by using the jacks arranged at the corresponding connection positions of the middle shield and the tail shield. The radius is measured and the data is recorded; (4) The right segment is installed. The right segment is hoisted downhole to the position to be assembled by using a crane and a hand-operated hoist, and is fixed by positioning and welding after the size tolerance is adjusted to -10-0 mm by using the jacks arranged at the corresponding connection positions of the middle shield and the tail shield. The radius is measured and the data is recorded; (5) The top segment is installed. The lifting lugs of the top segment are arranged in a triangular shape, and the two lifting lugs at the front are additionally provided with shackles. After being hoisted downhole, the size tolerance of the top segment is adjusted to 0-+10 mm by using the jacks arranged at the corresponding connection positions of the middle shield and the tail shield, and is fixed by positioning and welding. The radius is measured and the data is recorded; (6) The radius tolerance of the tail of the tail shield is adjusted to ±10 mm by using a total station instrument; (7) Process supports are arranged at the segment positions of the tail shield and the welding seam positions between the tail shield and the middle shield; (8) Each segment of the tail shield is welded. The inner side of each welding seam is first welded by bottom welding, and then the outer side is cleaned. The outer side of each welding seam is then welded by bottom welding. The welding seams opposite to each other at 180° are symmetrically welded. Each welding seam is segmented and welded; (9) The shell diameter is detected before formal welding, 15 minutes after single-side welding, 15 minutes after opposite-side welding and after the completion of overall welding. If the shell radius exceeds the required size, the shell is corrected according to the measurement data; (10) The circumferential welding seam between the tail shield and the middle shield is welded. The longitudinal seam is first welded, and then the transverse seam parallel to the axis of the shield body is welded; (11) The radius of the tail shield shell is reviewed. The measurement data and the required size of the shell radius are used for review and adjustment and correction, and the process supports are cut off; (12) The tail shield is brush-welded. The welding seam positions and the metal gloss on both sides are polished before welding. All kinds of tail shields are arranged in a staggered manner from front to back.
2. The method of claim 1, wherein, 3. The method of claim 1, wherein, In the step (1), the 0° or 180° center cross position line corresponding to the respective block is checked, and if not, the corresponding line is marked.
4. The method of claim 1, wherein, In the step (2), before hoisting, the welding position and the 50mm position on both sides of each block are polished to metal gloss.
5. The method of claim 1, wherein, In the step (3), step (4) or step (5), one end of the jack abuts against the edge of the tail shield, and the other end abuts against the corresponding wall of the L-shaped limiting plate fixed on the corresponding edge of the middle shield.
6. The method of claim 1, wherein, In the step (3), step (4) or step (5), the welding material used for the positioning welding is the same as that used for the formal welding in terms of preheating temperature and welding material, and the length is greater than 100mm.
7. The method of claim 1, wherein, In the step (7), the process support is a "concave" type rib plate.
8. The method of claim 1, wherein, In the step (9), the detection points for the shell diameter detection are the intersection points of the cross sections equally divided into three layers in the axial direction and the shield body.
9. The method of claim 1, wherein, In the step (9) or (11), the correction is carried out by mechanical or flame correction through a guide chain or oxygen-acetylene, and real-time measurement is carried out during the correction process.
Citation Information
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