A method for installing a turret propeller in stages with full azimuth rotation on a tugboat

Abstract

This invention belongs to the field of rudder propeller installation technology, specifically relating to a segmented installation method for a rudder propeller capable of azimuth rotation on a tugboat. Based on the design dimensions of the rudder propeller base, the method involves reverse manufacturing during segment production to form a segmented hull structure with a positioning reference surface. The segment is flipped over, and the centerline and baseline are used as theoretical positioning references. The center position of the rudder propeller base is determined and marked using a total station. The azimuth-rotating rudder propeller is hoisted, aligning its center with the base center, and initially fixed using an installation bracket. The welding strength is confirmed based on finite element analysis. After confirmation, the bracket is removed, and the rudder propeller base is welded to the base. The connection is then welded, and a rudder propeller sealing plate is welded on, completing the segmented installation. Through positioning and segmented installation, the accurate installation position of the rudder propeller is ensured, improving installation precision. The use of finite element analysis to confirm welding strength ensures structural reliability. The segmented operation reduces installation difficulty, improves installation efficiency, and ensures a stable connection between the rudder propeller and the base, which is beneficial for the stable operation of the tugboat.

Description

Technical Field

[0001] This invention belongs to the field of rudder propeller installation technology, specifically relating to a segmented installation method for a rudder propeller that rotates azimuthally on a tugboat. Background Technology

[0002] Azimuth propellers are a type of marine power unit that integrates propulsion and maneuvering functions. They are widely used in tugboats, marine engineering vessels, ferries, and other ship types that require high maneuverability.

[0003] Tugboat azimuth propeller installation is mostly carried out on the slipway or in dry dock. At this time, the hull sections have been joined together, and the propeller base is located in the narrow space under the hull. Construction workers have to work lying supine, their line of sight is obstructed, and it is difficult to set up measuring instruments.

[0004] When using a total station for surveying, the reference point is taken from the fixed control network on the slipway. The reference point transfer requires multiple station transfers, and each transfer increases the centering error. Moreover, the rudder propeller base is bolted to the base. When the rudder propeller is running, the lateral thrust generates alternating bending moments, causing fatigue cracks to form on the borehole walls at the bolted connections, affecting its later use. Summary of the Invention

[0005] This invention provides a method for the segmented installation of a turret propeller for azimuth-rotor tugboats. The propeller positioning and welding are completed in each segment. During the manufacturing process, a total station is used for layout to ensure that the positioning error meets requirements. Finite element analysis is employed beforehand to ensure welding strength. This method is applicable to the construction of twin-propeller tugboats.

[0006] Includes the following steps: S1: Based on the design dimensions and positioning parameters of the propeller base, the reverse mold manufacturing of the propeller base installation area is completed in advance during the segment manufacturing stage to form a hull segment structure with a positioning reference surface. S2: The completed hull sections are flipped over so that the bottom outer plate of the section is in a horizontal and upward position, and the centerline and baseline of the flipped section are used as the theoretical reference for the positioning of the propeller base. S3: Using a total station for benchmark positioning, with the centerline and baseline of the segment after overturning as references, the center position of the rudder propeller base is obtained, and the installation coordinates of the rudder propeller base are precisely set and marked. S4: Based on the set center position of the rudder propeller base, hoist the azimuth propeller onto the section, and adjust the position of the rudder propeller to align the center of the rudder propeller with the center position of the rudder propeller base. S5: After the rudder propeller is installed and aligned, the connection between the rudder propeller and the rudder propeller base is initially rigidly supported and temporarily fixed using the mounting plate, and the structural strength of the weld is confirmed to meet the requirements based on the finite element analysis results. S6: After confirming that the structural strength meets the requirements, remove the support plate bolts, take off the support plate, and weld the base of the rudder propeller to the rudder propeller base as one piece by welding. S7: Weld the connection between the propeller base and the propeller mount, and weld the propeller sealing plate to the bottom of the outer perimeter of the propeller base to complete the phased installation of the propeller and the base.

[0007] Preferably, S1 specifically includes the following steps: S11: Based on the design dimensions of the propeller base, a reverse tire frame is laid on the floor of the segment manufacturing workshop. The three-dimensional projection points of the segment centerline, baseline, and theoretical center of the propeller base are engraved on the frame panel. The coordinates of each support point on the frame panel are obtained by reverse calculation based on the outer plate shape value. S12: Lay the segmented bottom outer plate on the jig. Using the segment centerline and baseline as references, mark the rudder propeller base installation boundary line along the inner surface of the outer plate. Arrange multiple sets of positioning reference pins within the area enclosed by the boundary line. The height of each reference pin extending out of the inner surface of the outer plate is determined by the formula Hi=H0+Δi, where H0 is the theoretical installation height of the base and Δi is the actual surface deviation of the outer plate at the corresponding position. S13: Welded segmented structure, with an annular reinforcing elbow plate added to the back of the outer plate at the propeller base mounting position. The inner edge of the elbow plate is concentric with the theoretical center of the base, and the concentricity deviation is controlled within ±1.5mm. Three copper reference blocks distributed at 120° are pre-embedded on the surface of the elbow plate, and the normal of the working surface of each reference block points to the theoretical center axis of the base.

[0008] Preferably, S2 specifically includes the following steps: S21: Calculate the elastic deformation of the hull section during gravity overturning, weld reinforcing trusses on the non-stressed side of the section, and preset the reverse compensation angle according to the deformation. Use a gantry crane in conjunction with a turning frame to rotate the section 180° and place it on the support pier. S22: After the segment is stabilized, the physical centerline is constructed based on the cross-section of the main rib at both ends of the segment. Horizontal reference points are projected on the outer plates at the beginning and end of the segment to reproduce and mark the segment centerline and baseline after the overturning as theoretical references.

[0009] Preferably, S3 specifically includes the following steps: S31: Set the total station in a stable position around the segment, use the known control points on the slipway as the backsight reference, construct a measurement coordinate system, and detect the coordinates of the segment centerline and baseline reference points marked in step S2, and analyze the reference deviation correction value. S32: Extract the theoretical center coordinates and output shaft tilt angle from the propeller base design drawings, superimpose the reference deviation correction value calculated in step S31, and analyze the actual installation control coordinates of the propeller base on the segment. S33: Weld positioning code plates onto the segmented outer plate, set up theodolites and levels, adjust the position of the positioning code plates according to the actual installation control coordinates, and construct a virtual cross center line and height reference plane to support the positioning of the propeller base.

[0010] Preferably, S4 specifically includes the following steps: Four guide grooves are pre-machined on the lower surface of the rudder propeller base, radially distributed at 90° intervals; four guide sliders are welded to the corresponding positions on the upper surface of the rudder propeller base; the rudder propeller is lifted synchronously using two electric hoists; when the rudder propeller descends to the distance from the upper surface of the base, it is paused and the height difference between the four corners of the base is measured, and the height difference is finely adjusted using jacks; the rudder propeller continues to descend, so that the guide sliders are engaged with the guide grooves.

[0011] Preferably, S5 specifically includes the following steps: Six to eight support plates are evenly distributed around the circumference in the annular gap between the propeller base and the upper surface of the base panel. Each pallet includes an L-shaped pressure-bearing block that fits against the lower surface of the base flange, a bottom pad that fits against the upper surface of the base panel, and a bidirectional adjusting screw assembly connecting the two. Rotate the horizontal adjustment screw to make the inner side of the L-shaped block fit against the outer cylindrical surface of the base flange; rotate the vertical adjustment screw to make the upper surface of the L-shaped block fit against the lower surface of the base flange. After all the support plates are installed and spot-welded in place, use a total station to measure the coordinates of four pre-marked symmetrical points on the propeller base; compare the measured coordinates with the theoretical coordinates after alignment, and calculate the planar position deviation and height deviation. If the deviation exceeds the limit, it is corrected by fine-tuning the adjusting screw of the corresponding position of the support plate, and then the measurement is repeated until the accuracy requirements are met.

[0012] Preferably, S5 further includes the following steps: Call the pre-established finite element analysis model that includes the propeller, base plate, base and segmented structure; In the finite element analysis model, the actual position, quantity, and contact relationship of the pallets are applied as boundary conditions; based on the tugboat's operating conditions, the design load spectrum of the rudder propeller under maximum thrust, maximum rotational torque, and combined load is applied to the rudder propeller center of gravity position in the model in the form of force and torque. Perform static analysis to extract the equivalent stress of each pallet and the weld joint connecting it to the base; The maximum equivalent stress is compared with the allowable stress of the pallet and base panel materials; If the requirements are met, the structural strength of the temporary support system is deemed to meet the safety requirements during welding construction.

[0013] Preferably, S6 specifically includes the following steps: Loosen the bolts on the support plate and remove the support plate; use carbon arc gouging to remove the paint and oxide scale from the surface of the joint between the base and the pedestal; use gas shielded welding to divide the weld into 16 arc segments, each segment with a length of πD / 16, where D is the outer diameter of the base; welding sequence: first weld the 0° and 180° segments, then weld the 90° and 270° segments, then weld the 45°, 135°, 225°, and 315° segments, and finally weld the remaining 8 segments.

[0014] Preferably, step S1 further includes the following steps: Eight radial reinforcing elbows are arranged between the outer wall of the propeller base cylinder and the inner surface of the outer plate of the hull; the elbows are evenly distributed along the circumference of the cylinder, and the central angle between adjacent elbows is 45°. The thickness of the elbow plate is 0.8 to 1.0 times the thickness of the cylinder wall, and the radial length of the elbow plate is 0.6 to 0.8 times the height of the part of the cylinder that penetrates the outer plate. A horizontal annular reinforcing ring is set 150 mm to 200 mm below the upper end face of the cylinder. The reinforcing ring is welded to the outer wall of the cylinder with double-sided fillet welds. The lower surface of the reinforcing ring is connected to the flange of the eight elbow plates with fillet welds.

[0015] Preferably, during the temporary fixing process in step S5, the pre-tightening operation is performed alternately on both sides: First, pre-tighten a pair of support plates on the left rudder propeller base, then pre-tighten a pair of support plates on the right rudder propeller base at the same angle, and repeat this alternating sequence until all 8 support plates are pre-tightened. After welding, use a laser tracker to measure the position of the output shafts of the left and right rudder propellers respectively, calculate the parallelism deviation of the two shafts. If the included angle is greater than 0.05°, insert copper compensation shims between the outer edge of the two rudder propeller bases and the hull plate. The thickness distribution of the shims is calculated according to the tangent of the deviation angle. Tighten the sealing plate bolts and weld them again.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: This invention moves the propeller base installation process forward to the segmented reverse-molding stage. The base positioning reference is directly engraved on the mold panel, and after the segments are removed from the mold, the reference is transferred through copper pins and positioning holes. The segments are flipped so that the bottom outer plate faces upward, and the total station is set up on the platform above the segments, covering the entire measurement area in a single setup. The actual centerline and baseline coordinates of the inner surface of the segments are collected from multiple points, and the influence of local unevenness of the outer plate is eliminated by fitting the data using the least squares method.

[0017] During hoisting, this invention utilizes the wedge-shaped fit between the guide groove and the slider to achieve horizontal alignment. After the support plate is temporarily fixed, an overload with maximum thrust is applied using a finite element model, and strain gauge data is read in real time to calculate stress. If the stress exceeds the limit, the support plate density is increased. During the dual-propeller installation, the left and right base support plates are pre-tightened alternately. After welding, a laser tracker is used to measure the direction vectors of the two axes, and the angle between the horizontal and vertical planes is calculated. If the angle exceeds the tolerance, copper wedge-shaped shims are embedded for compensation, ensuring installation quality and accuracy.

[0018] This invention utilizes copper compensation shims whose texture is adapted to the deformation characteristics of the ship's structure, resulting in a high degree of fit after embedding. After secondary welding of the sealing plate, the overall structure is tightly fitted, preventing assembly gaps from gradually widening with navigation vibrations. A segmented reverse-molding process solidifies the rudder propeller base reference surface, and a total station accurately calibrates the installation coordinates, ensuring stable and controllable center alignment accuracy for each individual rudder propeller. Without bolted connections, the rudder propeller base and base are integrally fused and welded, eliminating gaps and channels at the connection points. This avoids the problem of alternating bending moments caused by lateral thrust during propeller operation, preventing fatigue cracks from arising from the bore walls at bolted connections. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Schematic diagram of the propeller base positioning; Figure 2 A schematic diagram showing the hoisting and centering of the azimuth propeller body; Figure 3 Schematic diagram of welding and sealing plate welding nodes for rudder propeller installation; Figure 4 This is a general layout diagram of the top layer of the twin rudder propellers on the hull. Figure 5 A schematic diagram showing the fit between the outer wall of the propeller base cylinder and the outer plate of the hull. Figure 6 for Figure 5 Schematic diagram of the M-direction. Detailed Implementation

[0021] The present invention Figures 1 to 4 middle, Figure 4 It is the overall layout drawing of the top layer of the twin rudder propellers on the bottom of the ship, which defines the symmetrical spacing of the twin rudder propellers, the overall axis deflection angle, and the installation vertical height parameters. Figures 1 to 3 It is a partial process implementation diagram, detailing the specific technical parameters and structural forms of single rudder propeller positioning, installation, and welding.

[0022] in Figure 4 In the middle, the azimuth propeller and fairing assembly 11 is based on the hoisting and alignment stage. The blade center is the reference point for judging the coaxiality of the propeller and assists in adjusting the alignment of the propeller and the center of the base.

[0023] Figure 4In the hull section, the bottom outer plate 12 serves as the mounting carrier for the rudder propeller base, bearing the loads during rudder propeller installation and operation. During the rollover manufacturing stage, the curved surface of the outer plate acts as the reference for the jig fabrication, and the pre-drilled openings provide space for the rudder propeller base installation. During the rollover stage, the horizontal orientation of the outer plate provides a stable operating plane for subsequent total station positioning and rudder propeller hoisting. During the sealing plate welding stage, the outer plate is welded to the rudder propeller sealing plate to achieve structural sealing and prevent seawater from entering the cabin. The azimuth-rotating rudder propeller upper power unit 13, comprising a motor, reducer, and slewing mechanism, is the power and control device for the rudder propeller and is installed above the hull base panel. During the hoisting and alignment stage, the center marker point of the power unit is a key reference for total station positioning; the rudder propeller position is adjusted by measuring the coordinates of this point.

[0024] The left rudder propeller output shaft deflection reference line 14 is the reference for the angle between the propeller's own axis and the vertical line of the hull during the hoisting and alignment stage in step S4. This reference line serves as a reference for adjusting the propeller's axis attitude. The angle between the axis and the reference line is measured using a total station to control the propeller deflection angle within the design range. During the welding stage, an inclinometer is used to monitor angle changes to prevent welding shrinkage from causing axis misalignment. The right rudder propeller output shaft deflection reference line 15 forms a 3° angle with the left rudder propeller output shaft deflection reference line 14. During the post-weld inspection stage, the deflection angle is compared to verify the parallelism of the two propeller axes. If the deviation exceeds the standard, it is adjusted using copper compensation shims. The lower swivel section 16 of the azimuth propeller connects the upper power unit and the propeller blades, including the base flange, sealing structure, and bearing components. It is the component that is welded and fixed to the hull base.

[0025] The present invention Figure 1 This is a schematic diagram of the rudder propeller base positioning. Figure 1 The transverse bulkhead 7 of the hull provides longitudinal boundary constraints for the rudder propeller base mounting area and is a segmented rigid load-bearing component. The rudder propeller base mounting area is a hull bottom outer plate 8 with openings. The rudder propeller base reinforcing elbow plate welded inside is the direct mounting carrier for the rudder propeller base and bears the entire load of the rudder propeller operation. Figure 1 The intersection point 1 of the output axis and the center line of the propeller mount is shown. The intersection point 1 of the output axis and the center line of the propeller mount serves as the coordinate origin for the entire process, providing a unified benchmark for design and construction. Figure 1 All positioning parameters, including the longitudinal, height, and lateral coordinates of the center of the propeller mount's upper surface, the center position of the hull plating openings, and the symmetrical dimension of 2650mm lateral distance from the center, are set with intersection point 1 as the reference. In subsequent steps, such as the reverse tire manufacturing in step S1, the arrangement of the jig support points, the layout of the hull plating openings, and the welding positioning of the internal reinforcing elbow plates are all controlled with intersection point 1 as the origin. In step S3, during total station positioning, intersection point 1 is used as the origin of the three-dimensional coordinate system to project the installation coordinates of the propeller mount, avoiding reference misalignment between segmented manufacturing and on-site installation.

[0026] Figure 2This is a schematic diagram showing the hoisting and centering of the azimuth rotor blade. Figure 2 The positions of the propeller body 3, the propeller base 4, and the transverse strong bulkhead 21 on the right side of the hull section are given.

[0027] The right-side transverse strong bulkhead 21 of the hull section provides structural boundary constraints for the rudder propeller installation area, bearing the loads during section hoisting, rudder propeller installation, and operation. In subsequent steps, specifically the S1 reverse molding stage, the bulkhead end face serves as the right-side forming boundary of the section. During the jig fabrication, this boundary is used as a reference to control the welding positions of the section's outer plates and internal reinforcing structures, preventing deformation of the right side of the section. In the S2 turning operation stage, the bulkhead bears the hoisting load, protecting the section structure from stress damage. Positioning marks on the bulkhead surface assist in verifying the position of the section's centerline and baseline. In the S3 total station positioning stage, the bulkhead serves as an auxiliary reference point, measuring its distance from the center of the rudder propeller base to verify the base's transverse positioning accuracy and prevent offset.

[0028] Figure 2 The azimuth propeller and fairing assembly 11 consists of blades, hub, and fairing, providing propulsion and steering thrust for the tugboat. The blade center axis is the core reference for propeller attitude control. In the subsequent S4 hoisting and alignment stage, the blade center axis serves as a reference for propeller coaxiality and attitude control. During hoisting, the propeller position is adjusted based on this reference to ensure that the blade center is aligned with the base center, while simultaneously adjusting the propeller axis deflection angle to the design 5°.

[0029] Figure 3 A schematic diagram of the welding and sealing plate welding nodes for the rudder propeller installation. Figure 3 The locations of support plate 5 and propeller sealing plate 6 are shown. The installation method of the support components, the welding process details of the main body connection, and the sealing structure of the bottom sealing plate are given.

[0030] The following combination Figures 1 to 4 The method for installing a turret propeller in stages with full azimuth capability on a tugboat, as described in this application, will be described in detail. Specific details, such as particular system structures and technologies, are presented for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0031] It should be understood that, when used in this specification, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please see Figure 1 The diagram shows a flowchart of a segmented installation method for a turret's azimuth propeller in a specific embodiment. The method includes: S1: Based on the design dimensions and positioning parameters of the propeller base, the reverse tire manufacturing of the propeller base installation area is completed in advance during the segment manufacturing stage to form a hull segment structure with a positioning reference surface.

[0034] As a specific implementation of step S1 in this embodiment, the following steps are included: S11: Based on the longitudinal FR=492.5, lateral center distance 2684.4 and height surface base plate 3343.4 in the design dimensions of the propeller base, a reverse tire frame is laid on the floor of the segment manufacturing workshop. The segment center line, baseline and the three-dimensional projection point of the theoretical center of the propeller base are engraved on the frame panel. The coordinates of each support point of the frame panel are obtained by reverse calculation based on the outer plate shape value.

[0035] S12: Lay the segmented bottom outer plate on the jig. Using the segment centerline and baseline as references, mark the rudder propeller base installation boundary line along the inner surface of the outer plate. Arrange multiple sets of positioning reference pins within the area enclosed by the boundary line. The height of each reference pin extending out of the inner surface of the outer plate is determined by the formula Hi=H0+Δi, where H0 is the theoretical installation height of the base and Δi is the actual surface deviation of the outer plate at this position.

[0036] S13: Welded segmented structure, with an annular reinforcing elbow plate added to the back of the outer plate at the propeller base mounting position. The inner edge of the elbow plate is concentric with the theoretical center of the base, and the concentricity deviation is controlled within ±1.5mm. Three copper reference blocks distributed at 120° are pre-embedded on the surface of the elbow plate, and the normal of the working surface of each reference block points to the theoretical center axis of the base.

[0037] In some embodiments, a segmented bottom outer steel plate, 20mm thick, is laid on the jig. Using the segmented centerline and baseline marked on the jig panel as alignment lines, the position of the steel plate is adjusted so that the pre-marked centerline on the steel plate coincides with the jig centerline. On the inner surface of the outer plate, two concentric circles are drawn with the theoretical center projection point of the base as the center, with radii R1=300mm and R2=2650mm respectively. The annular area between the two circles is the rudder propeller base installation boundary line. Sixteen positioning reference pins are evenly arranged along this annular boundary line. Each reference pin is made of round steel with a diameter of 20mm and a length of 60mm, one end of which is welded to the steel plate, and the other end is machined into a hemispherical shape.

[0038] Furthermore, the annular reinforcing elbow plate improves the local stiffness of the base mounting area, and the normal of the working surface of the copper reference block points to the theoretical central axis. When installing a total station for measurement, the reflecting prism can be vertically attached to the reference block, ensuring that the line of sight at each measurement point passes through the theoretical center, simplifying coordinate transformation calculations. The three reference blocks are distributed at 120°, so even if individual reference blocks are slightly deformed after segmented flipping or transportation, accurate center coordinates can still be obtained by fitting a spatial circle using three points.

[0039] Furthermore, in combination Figure 5 and Figure 6 As shown, between the outer wall 22 of the propeller base cylinder and the inner surface of the outer plate 23 of the hull, according to Figure 5 The eight cross-sectional orientations shown depict eight radially arranged elbow plates 24. The elbow plates 24 are evenly distributed along the circumference of the cylinder, with a central angle of 45° between adjacent elbow plates.

[0040] The thickness of the elbow plate 24 is 0.8 to 1.0 times the thickness of the cylinder wall, and the radial length of the elbow plate 24 is 0.6 to 0.8 times the height of the portion of the cylinder penetrating the outer plate. A single-sided V-shaped bevel is made between the elbow plate 24 and the outer wall of the cylinder and the inner surface of the outer plate. A horizontal annular reinforcing ring is installed 150mm to 200mm below the upper end face of the cylinder. The reinforcing ring is welded to the outer wall of the cylinder using double-sided fillet welds. The lower surface of the reinforcing ring is connected to the flange of the eight elbow plates using fillet welds. Flat steel stiffeners are arranged at intervals of 300mm to 350mm on the inner surface of the outer plate between adjacent elbow plates, and the stiffeners are staggered welded to the outer plate and the web of the elbow plate.

[0041] S2: The completed hull sections are flipped over so that the bottom outer plate of the section is in a horizontal and upward position, and the centerline and baseline of the flipped section are used as the theoretical reference for the positioning of the propeller base.

[0042] As a specific implementation of step S2 in this embodiment, the following steps are included: S21: The elastic deformation of the hull section during gravity overturning is obtained through finite element pre-analysis. Reinforcing trusses are welded on the non-stressed side of the section, and the reverse compensation angle is preset according to the deformation. The section is rotated 180° and placed on the support pier using a gantry crane and a turning frame. S22: After the segment is stabilized, the physical centerline is constructed based on the cross-section of the main rib at both ends of the segment. Horizontal reference points are projected on the outer plates at the beginning and end of the segment to reproduce and mark the segment centerline and baseline after the overturning as theoretical references.

[0043] It should be noted that the sections may have shifted after being flipped, and the theoretical lines on the jig cannot be directly used. Based on the principle that two points determine a straight line, the actual geometric center of the section is used as the reference for subsequent positioning, eliminating the influence of section manufacturing errors. Reproducing the baseline using a level instrument involves establishing a horizontal reference using a level instrument, accurately transferring the absolute elevation to the section, and establishing a local coordinate system independent of the slipway but related to the design.

[0044] Furthermore, gravity-driven tilting can be achieved by welding four sets of tilting lugs on both sides of the segment's center of gravity. Each set consists of a main lug and an auxiliary lug, using two gantry cranes. The main hook hooks the main lug, and the auxiliary hook hooks the auxiliary lug. When the segment's bottom surface is nearly level, the wire rope of the auxiliary hook is gradually transferred to the ground anchor point, while the main hook continues to lift the segment, detaching it from the jig. Once the segment is completely suspended, it is slowly rotated 180°, with the bottom outer plate facing upwards, and lowered onto the tilting support. A rubber pad is laid on top of the support, with the contact point located at the intersection of the hull's longitudinal skeletons.

[0045] S3: Using a total station for benchmark positioning, and taking the centerline and baseline of the segment after overturning as references, the center position of the propeller base is obtained, and the installation coordinates of the propeller base are precisely set and marked.

[0046] As a specific implementation of step S3 in this embodiment, the following steps are included: S31: Set the total station in a stable position around the segment, use the known control points on the slipway as the backsight reference, construct a measurement coordinate system, and detect the coordinates of the segment centerline and baseline reference points marked in step S2, and analyze the reference deviation correction value. S32: Extract the theoretical center coordinates (X0, Y0, Z0) and output shaft tilt angle β from the propeller base design drawings, and superimpose the reference deviation correction value calculated in step S31 to parse out the actual installation control coordinates of the propeller base on the segment. S33: Weld positioning code plates onto the segmented outer plate, set up theodolites and levels, adjust the position of the positioning code plates according to the actual installation control coordinates, and construct a virtual cross center line and height reference plane to support the positioning of the propeller base.

[0047] It should be noted that, based on a total station performing a 360° horizontal and vertical angle scan, at least three known coordinate points in the shipyard reference network are captured, and the station coordinates (Xs, Ys, Zs) are determined by least squares adjustment. Combining the measured coordinates (Xm, Ym, Zm) of the outer plate reference point in step S2 with the theoretical values ​​(Xt, Yt, Zt), the translation corrections ΔX, ΔY, ΔZ and the rotation correction angle are obtained.

[0048] Read the coordinates of the center point of the base bottom surface and the vector direction of the output axis, and raise the Z-axis coordinate. Here, combined with the translation correction obtained in step S31, the final installation control point coordinates are calculated using the coordinate transformation matrix T. P final =T×(P de +P co ) It should be noted that the coordinate transformation matrix T is used to transform coordinates from one coordinate system to another. For example, it transforms the design or theoretical coordinate system to the segmented actual coordinate system or construction coordinate system. In shipbuilding, due to factors such as segment turning, welding deformation, and installation deviations, the ideal coordinate values ​​P on the design drawings may differ. de It cannot be used directly; it is transformed to the actual position and attitude of the current segment via T.

[0049] P co The compensation correction is an adjustment value added to eliminate errors and meet process requirements. It includes an error correction component and a process elevation adjustment. The error correction component is the translation correction value obtained in step S31. Because after segmented rotation, the actual centerline and baseline may deviate from their theoretical positions, and the total station measured this deviation, P. co The value included in the formula is the one that counteracts this deviation.

[0050] The process elevation refers to raising the Z-axis coordinate. To compensate for shrinkage deformation after welding, a certain distance needs to be added to the design height.

[0051] According to the analysis of P final Based on the coordinates, several L-shaped positioning code plates are welded onto the segmented outer plate. The longitudinal and transverse center lines of the base are marked on the code plates using a laser beam projected by a theodolite and a scribing needle. The elevation of the top surface of the code plates is adjusted to form a support surface parallel to the bottom surface of the propeller base, and the code plates are spot-welded to form a rigid limiting frame. This eliminates the error caused by sag in the string method and ensures the positioning accuracy of the base before welding.

[0052] Of course, combined with appendix Figures 1 to 4 In summary, steps S31 to S33 involve placing the segment on the turning support and adjusting the height screws at the four corners of the support to make the centerline of the segment parallel to the ground baseline. A measuring platform is then erected above the segment, and the total station is fixed in place. First, the instrument is aimed at the intersection of the crosshairs pre-marked on the inner surface of the segment; this intersection is the reference point. Figure 1 The intersection of FR=492.5 and the centerline is used as the origin. A point is collected every 300mm along the longitudinal direction, for a total of 7 points, and a spatial straight line is fitted as the new centerline.

[0053] Similarly, collect 5 points along the horizontal direction to fit a new baseline. Calculate the intersection of the two lines. Input the design coordinates (492.5, 2684.4, 3343.4). Further, considering the elevation difference, change the input coordinates to (492.5, 2684.4, 3343.4 + elevation difference). Use the total station to calculate the stakeout point P. finalA vertical laser beam is emitted from the total station using a laser pointer, illuminating the inner surface of the outer plate to form a 2mm diameter spot. A circle is drawn along the edge of the spot using a scriber, and three 1.5mm locating holes are drilled inside the circle, arranged in an equilateral triangle with sides of 20mm. Copper pins are pressed into the three holes, and crosshairs are engraved on the top of the pins.

[0054] S4: Based on the set center position of the rudder propeller base, hoist the azimuth propeller onto the section, and adjust the position of the rudder propeller to align the center of the rudder propeller with the center position of the rudder propeller base.

[0055] In some embodiments, four guide grooves are pre-machined on the lower surface of the propeller base, radially distributed at 90° intervals. Four guide sliders are welded to corresponding positions on the upper surface of the propeller base, with the top of the sliders chamfered at 30°. The propeller is lifted synchronously using two electric hoists. When the propeller descends to a distance from the upper surface of the base, the hoisting is paused and the height difference between the four corners of the base is measured. The height difference is then finely adjusted using jacks. The descent continues until the guide sliders engage with the guide grooves. At this point, the axis of the base coincides with that of the base. Here, the guide grooves and sliders form a wedge-shaped slide, allowing the base to move horizontally until it is centered. The jack leveling prevents jamming caused by tilting during lifting.

[0056] S5: After the rudder propeller is installed and aligned, the connection between the rudder propeller and the rudder propeller base is initially rigidly supported and temporarily fixed using the mounting plate, and the structural strength of the weld is confirmed to meet the requirements based on the finite element analysis results.

[0057] The following is combined with Figure 3 As shown, 6 to 8 support plates are evenly distributed circumferentially within the annular gap between the propeller base and the upper surface of the base panel. Each support plate includes an L-shaped pressure-bearing block that fits against the lower surface of the base flange, a bottom pad that fits against the upper surface of the base panel, and a bidirectional adjusting screw assembly connecting the two. Rotate the horizontal adjusting screw to make the inner side of the L-shaped block fit against the outer cylindrical surface of the base flange; rotate the vertical adjusting screw to make the upper surface of the L-shaped block fit against the lower surface of the base flange. Spot weld the bottom pad of the support plate to the base panel.

[0058] Furthermore, after all the support plates are installed and spot-welded in place, the coordinates of four pre-marked symmetrical points on the propeller base are measured using a total station. The measured coordinates are then compared with the theoretical coordinates after alignment to calculate the planar position deviation and height deviation.

[0059] If the deviation exceeds the limit, it is corrected by fine-tuning the adjusting screws of the corresponding positions of the support plates, and then remeasured until the accuracy requirements are met. Finally, the locking nuts of all adjusting screws are tightened, and the L-shaped clamps are intermittently spot-welded to the edge of the base flange to form a temporary rigid constraint.

[0060] Furthermore, a pre-established finite element analysis model containing the rudder propeller, carrier plate, base, and segmented structure is invoked. In the finite element analysis model, the actual position, quantity, and contact relationship of the carrier plate are applied as boundary conditions. Based on the tugboat's operating conditions, the design load spectrum of the rudder propeller under maximum thrust, maximum rotational torque, and combined loads is applied as forces and moments to the rudder propeller's center of gravity position in the model.

[0061] Perform static analysis to extract the equivalent stress at each support plate and the weld joint connecting it to the base. Compare the maximum equivalent stress with the allowable stress of the support plate and base panel materials. If the requirements are met, the structural strength of the temporary support system is determined to meet the safety requirements during welding construction. If not, increase the number of support plates or adjust their layout, then remeasure and check the strength until the requirements are met.

[0062] As an example, a support plate can be inserted every 45° along the circumference of the base. The gaps between the support plate and the base / base are sealed with copper wedges. Each support plate is tightened with two M24 bolts. Eight sets of strain gauges are attached circumferentially to the upper surface of the base. A simulated thrust is applied to the propeller output shaft using a hydraulic cylinder. After loading, the strain values ​​are recorded, and the Mises stress is calculated according to the fourth strength theory. If the maximum stress is less than 0.8 times the material's yield strength, the strength is satisfied.

[0063] S6: After confirming that the structural strength meets the requirements, remove the support plate bolts, take off the support plate, and weld the base of the rudder propeller to the rudder propeller base as one piece.

[0064] In some embodiments, loosen the support plate bolts and remove the support plate. Use carbon arc gouging to remove paint and scale from the surface of the joint between the base and the pedestal. Use CO2 gas shielded welding to divide the weld into 16 arc segments, each segment being πD / 16 in length, where D is the outer diameter of the base. Welding sequence: first weld the 0° and 180° segments, then the 90° and 270° segments, followed by the 45°, 135°, 225°, and 315° segments, and finally the remaining 8 segments. Each segment is welded using multiple layers and multiple passes, and after each segment is welded, cover it with asbestos cloth for insulation. After all welding is completed, use ultrasonic testing to detect internal defects.

[0065] S7: Weld the connection between the propeller base and the propeller mount, and weld the propeller sealing plate to the bottom of the outer perimeter of the propeller base to complete the phased installation of the propeller and the base.

[0066] In some embodiments, four rudder propeller end plates are first spot-welded at the connection between the bottom perimeter of the propeller base and the hull hull. A prefabricated annular end plate is then hoisted into the V-groove of the rudder propeller end plate. The height of the end plate is adjusted so that its lower edge is flush with the inner surface of the hull hull hull and its upper edge is flush with the outer edge of the base. The rudder propeller end plates are removed, and continuous fillet welds are applied around the perimeter of the end plates. After welding, the remaining support plate bolts from step S5 are removed with a wrench, and all support plates are removed. The weld excess is ground down to be flush with the base material using an angle grinder. In this way, the end plates integrate the propeller with the hull, improving impact resistance. Removing the support plates leaves the structure with no extra parts, reducing weight.

[0067] In some specific embodiments, during step S4, the pre-tightening operation on both sides is performed alternately during the installation and alignment of the left and right rudder propeller bases and the temporary fixing process in step S5. First, pre-tighten the pair of support plates on the left rudder propeller base, that is, in the 0° and 180° directions. Then, pre-tighten the pair of support plates on the right rudder propeller base in the same angular direction. Repeat this alternating sequence until all 8 support plates are pre-tightened, and keep them stationary for 2 minutes between each stage.

[0068] Furthermore, after welding is completed, the positions of the output axes of the left and right rudder propellers are measured using a laser tracker, and the parallelism deviation of the two axes is calculated. If the included angle is greater than 0.05°, copper compensation shims are embedded between the outer edge of the two rudder propeller bases and the hull plate. The thickness distribution of the shims is calculated according to the tangent of the deviation angle. The sealing plate bolts are then tightened and repaired by welding.

[0069] It can be seen that alternating pre-tightening increases the clamping force on both sides of the base synchronously, preventing segmental lateral deflection during hoisting or welding of the other side after one side is completely locked. After all welding is completed, a laser tracker is used to install reflector ball mounts in the output shaft holes of the left and right rudder propellers respectively.

[0070] The 0.05° here is based on the requirement that the parallelism deviation of the output axis of a twin-propeller or multi-propeller propulsion system be controlled within 0.05°. The purpose is to prevent the yaw moment caused by inconsistent thrust directions of the two propellers, and to avoid the hull drifting and increasing fuel consumption.

[0071] The parallelism deviation between the two axes is calculated based on measuring the direction vector Vleft of the left axis and the direction vector Vright of the right axis in space. The parallelism deviation is calculated as follows: the angle θh in the horizontal plane = arctan(|Vleft.y - Vright.y| / longitudinal distance between the two measuring points), and the angle θv in the vertical plane = arctan(|Vleft.z - Vright.z| / lateral distance). If θh or θv > 0.05°, compensation is required.

[0072] Vleft.y is the Y-axis component of the direction vector of the left rudder propeller output axis perpendicular to the axis in the horizontal plane, i.e., the beam direction. Vright.y is the Y-axis component of the direction vector of the right rudder propeller output axis, i.e., the lateral slope of the right axis. Vleft.z is the vertical Z-axis component of the direction vector of the left rudder propeller output axis, equal to the Z-coordinate difference divided by the X-coordinate difference, reflecting the longitudinal inclination slope of the axis in the vertical plane. Vright.z is the Z-axis component of the direction vector of the right rudder propeller output axis, i.e., the vertical slope of the right axis.

[0073] The compensation method involves cutting copper plates with a thickness of 0.1mm to 2mm into wedge-shaped shims according to the direction of the deviation. The bolts connecting the base to the hull are then retightened, and the shims are spot-welded to their edges for fixation. After welding, the parallelism is re-measured until the angle between the two axes is ≤0.03°. Post-weld correction ensures that the propeller's thrust on the water flow is parallel, preventing yaw moment and hull vibration.

[0074] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0075] It should be understood that when an element or layer is referred to as being "connected" or "coupled" to another element or layer "on" it may be directly connected or coupled to said other element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element or layer "on" it is not an intermediate element or layer. Similar figures in all figures indicate similar elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0076] Spatially relative terms such as “below,” “under,” “lower,” “above,” “above,” etc., may be used here to describe the relationship between one element or feature and another, as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation other than those shown in the figure. For example, if the device in the figure were flipped over, the element described as “below” or “under” other elements or features would be facing “above” other elements or features. Thus, the exemplary term “below” can include both above and below orientations. Other orientations (rotation 90 degrees or other orientations) may be adopted, and the spatially relative terms used herein will be interpreted accordingly.

[0077] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the expression within this document. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that, when used in this specification, the term “comprising” means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for installing a turret propeller in stages with azimuth capability on a tugboat, characterized in that, Includes the following steps: S1: Based on the design dimensions and positioning parameters of the propeller base, the reverse mold manufacturing of the propeller base installation area is completed in advance during the segment manufacturing stage to form a hull segment structure with a positioning reference surface. S2: The completed hull sections are flipped over so that the bottom outer plate of the section is in a horizontal and upward position, and the centerline and baseline of the flipped section are used as the theoretical reference for the positioning of the propeller base. S3: Using a total station for benchmark positioning, with the centerline and baseline of the segment after overturning as references, the center position of the rudder propeller base is obtained, and the installation coordinates of the rudder propeller base are precisely set and marked. S4: Based on the set center position of the rudder propeller base, hoist the azimuth propeller onto the section, and adjust the position of the rudder propeller to align the center of the rudder propeller with the center position of the rudder propeller base. S5: After the rudder propeller is installed and aligned, the connection between the rudder propeller and the rudder propeller base is initially rigidly supported and temporarily fixed using the mounting plate, and the structural strength of the weld is confirmed to meet the requirements based on the finite element analysis results. S6: After confirming that the structural strength meets the requirements, remove the support plate bolts, take off the support plate, and weld the base of the rudder propeller to the rudder propeller base as one piece by welding. S7: Weld the connection between the propeller base and the propeller mount, and weld the propeller sealing plate to the bottom of the outer perimeter of the propeller base to complete the phased installation of the propeller and the base.

2. The method for installing a turret propeller in stages according to claim 1, characterized in that, S1 specifically includes the following steps: S11: Based on the design dimensions of the propeller base, a reverse tire frame is laid on the floor of the segment manufacturing workshop. The three-dimensional projection points of the segment centerline, baseline, and theoretical center of the propeller base are engraved on the frame panel. The coordinates of each support point on the frame panel are obtained by reverse calculation based on the outer plate shape value. S12: Lay the segmented bottom outer plate on the jig. Using the segment centerline and baseline as references, mark the rudder propeller base installation boundary line along the inner surface of the outer plate. Arrange multiple sets of positioning reference pins within the area enclosed by the boundary line. The height of each reference pin extending out of the inner surface of the outer plate is determined by the formula Hi=H0+Δi, where H0 is the theoretical installation height of the base and Δi is the actual surface deviation of the outer plate at the corresponding position. S13: Welded segmented structure, with an annular reinforcing elbow plate added to the back of the outer plate at the propeller base mounting position. The inner edge of the elbow plate is concentric with the theoretical center of the base, and the concentricity deviation is controlled within ±1.5mm. Three copper reference blocks distributed at 120° are pre-embedded on the surface of the elbow plate, and the normal of the working surface of each reference block points to the theoretical center axis of the base.

3. The method for segmented installation of a turret propeller with full azimuth capability as described in claim 1, characterized in that, S2 specifically includes the following steps: S21: Calculate the elastic deformation of the hull section during gravity overturning, weld reinforcing trusses on the non-stressed side of the section, and preset the reverse compensation angle according to the deformation. Use a gantry crane in conjunction with a turning frame to rotate the section 180° and place it on the support pier. S22: After the segment is stabilized, the physical centerline is constructed based on the cross-section of the main rib at both ends of the segment. Horizontal reference points are projected on the outer plates at the beginning and end of the segment to reproduce and mark the segment centerline and baseline after the overturning as theoretical references.

4. The method for segmented installation of a turret rudder propeller as described in claim 1, characterized in that, S3 specifically includes the following steps: S31: Set the total station in a stable position around the segment, use the known control points on the slipway as the backsight reference, construct a measurement coordinate system, and detect the coordinates of the segment centerline and baseline reference points marked in step S2, and analyze the reference deviation correction value. S32: Extract the theoretical center coordinates and output shaft tilt angle from the propeller base design drawings, superimpose the reference deviation correction value calculated in step S31, and analyze the actual installation control coordinates of the propeller base on the segment. S33: Weld positioning code plates onto the segmented outer plate, set up theodolites and levels, adjust the position of the positioning code plates according to the actual installation control coordinates, and construct a virtual cross center line and height reference plane to support the positioning of the propeller base.

5. The method for segmented installation of a turret propeller with full azimuth capability as described in claim 1, characterized in that, S4 specifically includes the following steps: Four guide grooves are pre-machined on the lower surface of the rudder propeller base, radially distributed at 90° intervals; four guide sliders are welded to the corresponding positions on the upper surface of the rudder propeller base; the rudder propeller is lifted synchronously using two electric hoists; when the rudder propeller descends to the distance from the upper surface of the base, it is paused and the height difference between the four corners of the base is measured, and the height difference is finely adjusted using jacks; the rudder propeller continues to descend, so that the guide sliders are engaged with the guide grooves.

6. The method for segmented installation of a turret propeller with full azimuth capability as described in claim 1, characterized in that, S5 specifically includes the following steps: Six to eight support plates are evenly distributed around the circumference in the annular gap between the propeller base and the upper surface of the base panel. Each pallet includes an L-shaped pressure-bearing block that fits against the lower surface of the base flange, a bottom pad that fits against the upper surface of the base panel, and a bidirectional adjusting screw assembly connecting the two. Rotate the horizontal adjustment screw to make the inner side of the L-shaped block fit against the outer cylindrical surface of the base flange; rotate the vertical adjustment screw to make the upper surface of the L-shaped block fit against the lower surface of the base flange. After all the support plates are installed and spot-welded in place, use a total station to measure the coordinates of four pre-marked symmetrical points on the propeller base; compare the measured coordinates with the theoretical coordinates after alignment, and calculate the planar position deviation and height deviation. If the deviation exceeds the limit, it is corrected by fine-tuning the adjusting screw of the corresponding position of the support plate, and then the measurement is repeated until the accuracy requirements are met.

7. The method for segmented installation of a turret propeller with full azimuth capability as described in claim 6, characterized in that, S5 also includes the following steps: Call the pre-established finite element analysis model that includes the propeller, base plate, base and segmented structure; In the finite element analysis model, the actual position, quantity, and contact relationship of the pallets are applied as boundary conditions; based on the tugboat's operating conditions, the design load spectrum of the rudder propeller under maximum thrust, maximum rotational torque, and combined load is applied to the rudder propeller center of gravity position in the model in the form of force and torque. Run static analysis to extract the equivalent stress of each pallet and the weld joint connecting it to the base; The maximum equivalent stress is compared with the allowable stress of the pallet and base panel materials; If the requirements are met, the structural strength of the temporary support system is deemed to meet the safety requirements during welding construction.

8. The method for installing a turret propeller in stages according to claim 1, characterized in that, S6 specifically includes the following steps: Loosen the bolts on the support plate and remove the support plate; use carbon arc gouging to remove the paint and oxide scale from the surface of the joint between the base and the pedestal; use gas shielded welding to divide the weld into 16 arc segments, each segment with a length of πD / 16, where D is the outer diameter of the base; welding sequence: first weld the 0° and 180° segments, then weld the 90° and 270° segments, then weld the 45°, 135°, 225°, and 315° segments, and finally weld the remaining 8 segments.

9. The method for segmented installation of a turret propeller with full azimuth capability as described in claim 1, characterized in that, Step S1 also includes the following steps: Eight radial reinforcing elbows are arranged between the outer wall of the propeller base cylinder and the inner surface of the outer plate of the hull; the elbows are evenly distributed along the circumference of the cylinder, and the central angle between adjacent elbows is 45°. The thickness of the elbow plate is 0.8 to 1.0 times the thickness of the cylinder wall, and the radial length of the elbow plate is 0.6 to 0.8 times the height of the part of the cylinder that penetrates the outer plate. A horizontal annular reinforcing ring is set 150 mm to 200 mm below the upper end face of the cylinder. The reinforcing ring is welded to the outer wall of the cylinder with double-sided fillet welds. The lower surface of the reinforcing ring is connected to the flange of the eight elbow plates with fillet welds.

10. The method for installing a turret's azimuth propeller in stages according to claim 1, characterized in that, During the temporary fixation process in step S5, the pre-tightening operation is performed alternately on both sides: First, pre-tighten a pair of support plates on the left rudder propeller base, then pre-tighten a pair of support plates on the right rudder propeller base at the same angle, and repeat this alternating sequence until all 8 support plates are pre-tightened. After welding, use a laser tracker to measure the position of the output shafts of the left and right rudder propellers respectively, calculate the parallelism deviation of the two shafts. If the included angle is greater than 0.05°, insert copper compensation shims between the outer edge of the two rudder propeller bases and the hull plate. The thickness distribution of the shims is calculated according to the tangent of the deviation angle. Tighten the sealing plate bolts and weld them again.

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