A normal construction method of a bow section plate of a ship

Abstract

The application discloses a normal construction method of a bow section plate of a ship, and belongs to the technical field of ship construction. According to the designed lines of the bow section plate, the method establishes a normal construction control coordinate system on a ship baseline plane, and divides the bow section plate into a plurality of curvature strips. The theoretical plate surface of each curvature strip is discretized into a plurality of normal control points, a normal point cloud sequence of each curvature strip is generated, a surface normal constraint line is constructed by using adjacent normal control points, a fairing transition parameter is calculated, a cradle support height program sequence is generated, the cradle is arranged according to the cradle support height program sequence, the posture of the curvature strip is adjusted, and the normal control points of adjacent curvature strips are aligned. Positioning welding is performed at the joint of the curvature strips, the actual coordinates of the normal control points on both sides of the joint are collected again after the positioning welding, the cradle support height program sequence is updated, and the normal construction of the bow section plate is completed. The method can reduce the normal deviation of the plate and the deformation accumulation after the positioning welding.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, specifically to a normal construction method for the bow section outer plating of a ship. Background Technology

[0002] The bow section outer plating of a ship features complex shapes such as the bowstock angle, large curvature flare, and deck edge contraction. Normal construction is a crucial step in the assembly of ship sections and the control of hull lines. In existing technologies, normal construction of the bow section outer plating mainly relies on manual templates, wooden molds, or simple jigs for shape positioning, using rib lines and markings as references for plating installation and assembly. During the construction preparation phase, the division of curvature slats is largely done by operators based on experience, lacking a unified coordinate reference based on the hull baseline plane and centerline plane. This results in inconsistencies between the normal direction of the outer plating surface and the jig support direction, leading to unstable attitude control of the outer plating on the jig.

[0003] In terms of curvature slat support positioning, existing methods typically use the measured elevations at discrete rib or longitudinal bone positions as the jig support height, failing to discretize the outer plate surface into normal control points or form continuous normal constraint lines. The lack of correlation between normal control points between adjacent curvature slats easily leads to misalignment and uneven gaps in the normal direction of the outer plate surfaces on both sides of the joint. When the curvature of the curvature slats varies significantly, the fixed jig support height struggles to match the normal changes of the outer plate surface, resulting in localized areas of suspension or over-constraint, and an increased deviation between the outer plate surface and the theoretical profile.

[0004] During the tack welding stage, existing methods generally do not re-acquire the actual coordinates of the normal control points on both sides of the joint after the tack welding is completed, and the jig support elevation sequence is not corrected based on the measured deformation. The local shrinkage and warping caused by tack welding will cause the normal control points to deviate from their theoretical positions. Without a closed-loop support elevation update mechanism, the subsequent formal welding of the curvature slat joint and the assembly of adjacent slats will continue to accumulate errors on the basis of the existing deformation, requiring a lot of fire correction and secondary adjustments.

[0005] To address the aforementioned issues, a normal construction control coordinate system needs to be established on the hull baseline plane. A jig support elevation sequence is generated using normal control points and surface normal constraint lines. After tack welding, the actual coordinates are re-acquired to update the support elevation sequence, thus avoiding accuracy losses caused by inconsistent outer plate surface normal control benchmarks and the inability to dynamically compensate for support elevations. Summary of the Invention

[0006] To address the issues of lack of a unified benchmark for the normal control points of curvature slats, missing normal constraint lines for curved surfaces, and the inability of the jig support height sequence after positioning welding to dynamically update based on measured coordinates, which lead to the normal deviation and deformation accumulation of the outer plate, a normal construction method for the bow section outer plate of a ship is proposed.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a normal construction method for the bow section outer plating of a ship. Based on the design profile of the bow section outer plating, a normal construction control coordinate system is established on the hull baseline plane. Using the hull centerline plane and the hull baseline plane as coordinate reference planes, the bow section outer plating is divided into multiple curvature slats. The theoretical outer plating surface of each curvature slat is discretized into several normal control points, generating a normal point cloud sequence for each curvature slat. Adjacent normal points in the normal point cloud sequence are used as the reference points for the construction of the bow section outer plating. Control points are used to construct surface normal constraint lines, and the smooth transition parameters between these lines are calculated to generate a jig support elevation sequence. The jig is then arranged according to this sequence, and the curvature slats are hoisted onto it. The attitude of the curvature slats is adjusted using the surface normal constraint lines as a reference to align the normal control points of adjacent curvature slats. Tack welding is performed at the joints of the curvature slats. After tack welding, the actual coordinates of the normal control points on both sides of the joint are re-acquired, and the jig support elevation sequence is updated, completing the normal construction of the bow section outer plate. This construction method forms a closed loop between the design profile, normal control points, surface normal constraint lines, and jig support elevation, ensuring that the curvature slats remain consistent with the theoretical outer plate surface under normal construction conditions, reducing joint misalignment and local deformation.

[0008] As a specific implementation method, the process of establishing a normal construction control coordinate system includes: extracting the bow outline, deck edge line, and outer plating development line from the design lines of the bow section outer plating; dividing the outer plating development line into layers according to the design waterline intervals; using the intersection of the hull centerline plane and the hull baseline plane as the longitudinal reference axis, and the intersection of the longitudinal reference axis and the bow perpendicular as the coordinate origin; establishing a normal construction control coordinate system at the coordinate origin, ensuring that the horizontal plane of this coordinate system coincides with the hull baseline plane, the longitudinal axis points towards the stern along the longitudinal reference axis, and the transverse axis is perpendicular to the hull centerline plane; converting the various shape value points on the outer plating development line to the normal construction control coordinate system, and using the converted shape value points as the dividing boundaries of multiple curvature slats. This method can unify the coordinate references of the design lines, dividing boundaries, and subsequent normal control points, reducing errors introduced by multiple coordinate transformations.

[0009] Preferably, when dividing the bow section outer plate into multiple curvature strips, the initial dividing line is generated at equal arc length intervals along the direction of the greatest longitudinal curvature gradient of the outer plate, using the bow column angle line as the starting boundary. A geometric check is performed on the strip area enclosed by the initial dividing line and the outer plate boundary. When the initial dividing line passes through an elbow plate seat or manhole on the outer plate, the initial dividing line is reoriented along the edge of the elbow plate seat or manhole to obtain the actual dividing line. The actual dividing line is mapped onto the outer plate surface, and each curvature strip is numbered according to the direction of the actual dividing line, generating multiple curvature strips. This avoids local opening structures such as elbow plate seats and manholes, making the strip boundaries more adaptable to the characteristics of the outer plate structure and reducing interference between later joints and structural openings.

[0010] Preferably, when discretizing the theoretical outer plate surface of each curvature slat into several normal control points, sampling grids are arranged on the theoretical outer plate surface of each curvature slat according to the rib spacing and longitudinal rib spacing, and the nodes of the sampling grids are used as candidate control points. A normal line is drawn through each candidate control point to the outer plate surface, and the intersection of the normal line and the hull baseline plane is marked as the projection foot point. The candidate control point is then translated outward along the normal line by a plate thickness distance to obtain the neutral surface control point of the outer plate. The neutral surface control point of the outer plate and the corresponding projection foot point form a normal control point pair. All normal control point pairs are arranged in the longitudinal order of the curvature slats to generate a normal point cloud sequence. This normal point cloud sequence contains both surface position and outer plate thickness direction information, providing a unified positioning reference for subsequent constraint line construction, jig support elevation calculation, and slat attitude adjustment.

[0011] As a technical solution of this invention, the process of constructing surface normal constraint lines using adjacent normal control points in the normal point cloud sequence, calculating smooth transition parameters between the surface normal constraint lines, and generating a jig support height sequence includes: sequentially connecting adjacent normal control points in the normal point cloud sequence to form initial constraint polylines; projecting the initial constraint polylines onto the hull baseline plane to obtain projected polylines, and associating each inflection point of the projected polylines with the corresponding normal control points; using the arc length and the included angle between adjacent normal control points as smooth transition parameters, smoothing the initial constraint polylines according to the smooth transition parameters to obtain surface normal constraint lines; extending each point on the surface normal constraint lines along the opposite direction of the outer plate surface normal to the top surface of the jig, extracting the vertical height of each extended point, arranging the vertical heights according to the direction of the projected polylines, and generating a jig support height sequence. This process converts the curvature change of the outer plate surface into the elevation change of the jig top surface, which is beneficial for the accurate matching of the jig support height with the outer plate curvature.

[0012] During the jig arrangement and curvature slat hoisting stages, each elevation value in the jig support elevation sequence is assigned to the corresponding jig lifting cylinder, generating a lifting cylinder stroke command. The lifting height of each jig lifting cylinder is adjusted according to the stroke command, and a set of wooden blocks matching the curvature of the outer plate of the curvature slat is installed on the top surface of the jig. The curvature slat is hoisted onto the wooden blocks, and positioning reference points are set at the four corners of the curvature slat. The actual coordinates of the positioning reference points are measured using a total station, and the actual coordinates are correlated with the coordinates of the corresponding normal control points on the surface normal constraint line. The stroke of the jig lifting cylinder and the height of the local wooden blocks in the wooden blocks are adjusted to ensure that the outer plate surface of the curvature slat conforms to the surface normal constraint line. This achieves the initial positioning of the curvature slat on the jig, ensuring that the outer plate surface conforms to the theoretical constraint line, providing a basis for the alignment of adjacent slats.

[0013] When aligning the normal control points of adjacent curvature slats, select paired normal control points at the same rib position on both sides of the joint of adjacent curvature slats. Use the normal control point on the side of the preceding curvature slat as a fixed point. Adjust the support height of the subsequent curvature slat at the corresponding position in the jig support height sequence so that the normal control point on the side of the subsequent curvature slat coincides with the fixed point. Arrange ceramic pads at equal intervals along the joint direction within the overlapped joint area, ensuring that the thickness direction of the ceramic pads is perpendicular to the outer plate surface on both sides of the joint. Apply temporary constraints to the overlapped paired normal control points, and repeat the operation by selecting paired normal control points at the next rib position until all normal control points of adjacent curvature slats are aligned. This step ensures that adjacent slats form a continuous outer plate surface at the joint, reducing the misalignment at the joint.

[0014] During the tack welding process, the joint is divided into multiple tack welding sections from the lower end to the upper end of the bow section outer plate. Each tack welding section contains at least two rib spacings. Within each tack welding section, tack welding points and saddle plates are alternately arranged along the joint centerline, with the saddle plates spanning the curved strips on both sides of the joint. For the current tack welding section, welding is performed sequentially from the tack welding point in the middle of the section to the tack welding points at both ends of the section. After each tack welding section is completed, the current coordinates of the normal control points on both sides of the joint of that section are collected, and the current coordinates are converted into correction values ​​for the corresponding support elevations in the jig support elevation sequence. The corrected support elevation is used as the constraint value for the next tack welding section, and the welding of all tack welding sections is completed sequentially. This method of segmented welding, welding from the middle to both ends, and combining saddle plate constraints can control the shrinkage deformation during the welding process, gradually compensating for the deviations of each tack welding section.

[0015] After tack welding, the actual coordinates of the normal control points on both sides of the joint are re-acquired. When updating the jig support height program, the sampling position is determined along the joint length direction according to the spacing between adjacent ribs. The actual coordinates of the normal control points on both sides of the joint are collected at the sampling position. The actual coordinates of the same normal control point are matched with the corresponding support elevation in the jig support height program to determine the support elevation compensation amount corresponding to the normal control point. The corresponding support elevation in the jig support height program is reverse-corrected according to the support elevation compensation amount to generate a corrected jig support height program. The corrected jig support height program is sent to the jig lifting cylinder, so that the jig lifting cylinder adjusts the support height corresponding to the joint area according to the corrected jig support height program. Through re-measurement and reverse correction after tack welding, the local deviations caused by tack welding can be eliminated in time, improving the surface fit before subsequent formal welding.

[0016] After the template support height sequence is updated, a re-measurement grid is arranged on the outer plate surface of the bow section outer plate according to the rib positions and longitudinal rib spacing. The actual coordinates of each node of the re-measurement grid are collected, and the normal vector of the outer plate surface at each node is obtained. The normal vector is spatially registered with the design outer plate normal corresponding to that node to obtain the distribution of the outer plate surface normal vector. Based on the distribution of the outer plate surface normal vector, the local support elevation in the template support height sequence is adjusted so that the distribution of the outer plate surface normal vector is orthogonal to the theoretical outer plate surface. During the period of maintaining the orthogonality, the formal welding of the curvature slat joints and the treatment of the weld excess height are completed in sequence to obtain the normally constructed bow section outer plate. This re-measurement and adjustment process ensures that the section outer plate maintains the design normal state before and after formal welding, further improving the construction accuracy of the bow section outer plate.

[0017] The technical effects and advantages provided by the present invention in the above technical solution are as follows: Based on the design lines of the bow section outer plating, a normal construction control coordinate system is established on the hull baseline plane, using the hull centerline plane and the hull baseline plane as coordinate reference planes. The outer plating is divided into multiple curvature strips. The theoretical outer plating surface of each curvature strip is discretized into several normal control points, generating a normal point cloud sequence. Normal constraint lines are constructed using adjacent normal control points, and smooth transition parameters between the normal constraint lines are calculated to generate a jig support elevation sequence. The support height of the curvature strips is calculated from the normal control points and the continuous surface normal constraint lines. The jig support elevation is consistent with the normal direction of the outer plating surface, thus avoiding normal offset and local overhang of the outer plating surface on the jig. The normal control points of adjacent curvature strips are aligned with the same coordinate reference, resulting in a continuous transition of the outer plating surfaces on both sides of the joint, reducing misalignment, and improving the smoothness of the outer plating lines.

[0018] After the tack welding of the curvature slat joint is completed, the actual coordinates of the normal control points on both sides of the joint are re-acquired. These actual coordinates are then matched with the corresponding support elevations in the jig support elevation program to determine the support elevation compensation amount corresponding to the normal control points. The jig support elevation program is then reverse-corrected and sent to the jig lifting cylinder to adjust the support height of the joint area. The local shrinkage and warping deformation caused by the tack welding can be fed back by the measured coordinates, dynamically compensating for the jig support elevation and allowing the normal control points between adjacent curvature slats to be realigned. Subsequent formal welding of the curvature slat joint is carried out under the corrected support condition, reducing deformation accumulation, extending the time the outer plate surface normal vector remains orthogonal to the theoretical outer plate surface, and reducing the workload of flame straightening. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0020] Figure 1 This is a flowchart of the normal construction method for the bow section outer plating of a ship; Figure 2 This is a flowchart illustrating the method for dividing the curvature slats of the outer plate of the bow section; Figure 3 This is a flowchart of the registration and adjustment process for the normal vector of the re-measurement grid on the outer plate of the bow section; Figure 4 This is a comparison diagram of the normal point cloud sequence of the curvature slats and the vertical coordinate sequence of the high-order sequence of the jig support; Figure 5 It is a diagram showing the target elevation, actual elevation, and vertical deviation distribution of the positioning reference point for the lifting cylinder of the jig frame; Figure 6 This is a diagram showing the distribution of the normal deviation angle of the grid nodes in the bow section of the outer plate. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0022] See Figure 1 This invention provides a normal construction method for the bow section outer plating of a ship, comprising: establishing a normal construction control coordinate system on the hull baseline plane according to the design lines of the bow section outer plating, wherein the normal construction control coordinate system uses the hull centerline plane and the hull baseline plane as coordinate reference planes, and dividing the bow section outer plating into multiple curvature strips; discretizing the theoretical outer plating surface of each curvature strip into several normal control points, generating a normal point cloud sequence for each curvature strip; and constructing a surface using adjacent normal control points in the normal point cloud sequence. Normal constraint lines are calculated, and smooth transition parameters between the surface normal constraint lines are generated to create a jig support height sequence. The jig is arranged according to the jig support height sequence, and the curvature slats are hoisted onto the jig. The attitude of the curvature slats is adjusted with the surface normal constraint lines as a reference to align the normal control points of adjacent curvature slats. Position welding is performed at the joints of the curvature slats. After position welding, the actual coordinates of the normal control points on both sides of the joint are re-acquired, and the jig support height sequence is updated to complete the normal construction of the bow section outer plate.

[0023] In specific implementation, please refer to Figure 2 The bow outline, deck edge line, and outer plate development line are extracted from the design lines of the bow section outer plating. The bow outline is the intersection line of the bow outer plating and the bow structure on the lines drawing; the deck edge line is the intersection line of the deck edge and the outer plating on the lines drawing; and the outer plate development line is the outline curve after the outer plating surface is developed. The outer plate development line is layered according to the design waterline. Specifically, the design lines data are read from the hull design software, and a horizontal section is established at each design waterline height. The intersection of the horizontal section and the outer plate development line is obtained to obtain the layer intersection point, which serves as the layer value point of the outer plate development line.

[0024] In some embodiments, the intersection of the hull centerline plane and the hull baseline plane is used as the longitudinal reference axis. The hull centerline plane is the plane of symmetry of the hull, and the hull baseline plane is a plane passing through the bottom baseline and parallel to the design waterline. The longitudinal reference axis is the straight line intersecting the hull centerline plane and the hull baseline plane. The intersection of the longitudinal reference axis and the bow perpendicular is used as the origin of the coordinate system. The bow perpendicular is a perpendicular line passing through the leading edge of the bowpost and perpendicular to the hull baseline plane.

[0025] In some embodiments, a normal construction control coordinate system is established at the origin. The horizontal plane of the normal construction control coordinate system coincides with the hull baseline plane. The longitudinal axis of the normal construction control coordinate system points towards the stern along the longitudinal reference axis, the transverse axis of the normal construction control coordinate system is perpendicular to the hull centerline plane and points towards the starboard side, and the vertical axis of the normal construction control coordinate system is determined according to the right-hand rule and points vertically upward. The various model points on the outer plate development line are converted to the normal construction control coordinate system. The conversion process is as follows: obtain the coordinate values ​​of each model point in the original hull coordinate system; obtain the coordinate values ​​of the origin in the original hull coordinate system as a translation vector; obtain the normals of the hull centerline plane and the hull baseline plane to construct a rotation matrix; subtract the translation vector from the original hull coordinates of each model point and multiply by the rotation matrix to obtain the coordinates of each model point in the normal construction control coordinate system. The converted model points serve as the dividing boundaries for multiple curvature slats.

[0026] In practical implementation, the bow column bend line in the design profile of the bow section outer plate is used as the starting boundary. The bow column bend line is the profile where the curvature of the bow outer plate changes at the bow column. Initial dividing lines are generated at equal arc length intervals along the direction of the maximum longitudinal curvature gradient of the outer plate. The longitudinal curvature gradient of the outer plate is the first derivative of the curvature of the outer plate surface with respect to the arc length along the longitudinal arc length direction. When obtaining the direction of the maximum longitudinal curvature gradient of the outer plate, the first derivative of the longitudinal curve curvature with respect to the longitudinal arc length at each point on the outer plate surface is calculated as the longitudinal curvature change rate. The longitudinal tangent direction at the point with the largest absolute value of the longitudinal curvature change rate is taken as the dividing line advancement direction. The equal arc length interval is obtained by dividing the total longitudinal arc length of the outer plate by the number of preset curvature strips. The number of preset curvature strips is converted from the maximum strip width given by the construction accuracy requirements. The conversion method is to divide the total longitudinal arc length of the outer plate by the maximum strip width and round up. Initial dividing lines are generated sequentially along the direction of advancement of the dividing lines at equal arc length intervals until the entire width of the bow section outer plate is covered.

[0027] In some embodiments, a geometric check is performed on the slatted area enclosed by the initial dividing line and the outer plate boundary. The outer plate boundary includes the bow bend line, the deck edge line, and the stern boundary of the outer plate unfolding line. During the geometric check, the outlines of the elbow plate seat and the manhole on the outer plate are extracted, and projected onto the outer plate surface to obtain the elbow plate seat boundary curve and the manhole boundary curve. It is determined whether the initial dividing line intersects with the elbow plate seat boundary curve or the manhole boundary curve. When the initial dividing line passes through the elbow plate seat or manhole on the outer plate, the initial dividing line is reoriented along the edge of the elbow plate seat or manhole. The specific method of reorientation is as follows: on the elbow plate seat boundary curve or the manhole boundary curve, take the two edge points closest to the entry point and exit point of the initial dividing line, and replace the corresponding arc segment of the initial dividing line between the entry point and the exit point with the arc segment of the elbow plate seat boundary curve or the manhole boundary curve between the two edge points. After replacement, the actual dividing line is formed. The slat area enclosed by the actual dividing line after reorientation and the outer plate boundary does not pass through the elbow plate seat or manhole.

[0028] In some embodiments, the actual dividing lines are mapped to the outer plate surface. The actual dividing lines are generated on the dividing plane or unfolding plane. They are mapped to the three-dimensional outer plate surface according to the parametric mapping relationship of the outer plate surface, resulting in three-dimensional actual dividing lines located on the outer plate surface. Each curvature slat is numbered according to the direction of the actual dividing lines. Numbering is performed longitudinally along the outer plate from bow to stern, and transversely from the hull centerline to the hull side, with numbers increasing sequentially. After all numbering is completed, multiple curvature slats are generated.

[0029] In practice, sampling grids are arranged on the theoretical outer plate surface of each curvature slat according to the rib spacing and longitudinal rib spacing. The rib spacing is the distance between adjacent ribs, and the longitudinal rib spacing is the distance between adjacent longitudinal ribs. The rib spacing and longitudinal rib spacing values ​​are read from the hull structure drawings. Within the parameter domain of the theoretical outer plate surface, the hull is divided at equal intervals according to the rib spacing along the longitudinal parameter direction and at equal intervals according to the longitudinal rib spacing along the vertical parameter direction, forming a parameter domain grid line group. The intersection points of each grid line in the parameter domain grid line group are mapped to the three-dimensional outer plate surface to obtain sampling grid nodes, which serve as candidate control points. Each parameter domain grid line, after being mapped to the three-dimensional outer plate surface, becomes a curve on the outer plate surface, and the intersection points of the parameter domain grid lines are mapped to corresponding points on the outer plate surface.

[0030] Draw a normal to the outer plate surface through each candidate control point. The normal to the outer plate surface is a straight line passing through the candidate control point and perpendicular to the tangent plane of the outer plate surface at the candidate control point. The tangent plane of the outer plate surface at the candidate control point is determined by the plane formed by the two parametric directional partial derivatives of the outer plate surface at the candidate control point. Mark the intersection of the normal and the hull baseline plane as the projection foot point. The hull baseline plane is the horizontal plane of the established normal construction control coordinate system. When the normal is parallel to the hull baseline plane, draw a perpendicular line to the hull baseline plane through the candidate control point, and use the foot of the perpendicular as the projection foot point. Translate the candidate control point along the normal to the outer plate by a plate thickness distance to obtain the neutral surface control point of the outer plate. The plate thickness distance is the design plate thickness value of the outer plate, and the outer side of the outer plate is the side of the outer plate surface away from the internal space of the hull. The neutral surface control point of the outer plate is located on the neutral surface of the outer plate, and the neutral surface control point of the outer plate and the projection foot point form a normal control point pair. In the normal control point pair, the neutral surface control point of the outer plate is used to describe the position of the outer plate surface, and the projection foot point is used to describe the projection reference position on the normal of the outer plate surface. All normal control point pairs are arranged in longitudinal order along the curvature slats to generate a normal point cloud sequence. The longitudinal order of the curvature slats is from the first end to the second end along the length of the curvature slat, with the first end being the end closer to the bow and the second end being the end closer to the stern. Normal control point pairs within the same curvature slat are numbered in longitudinal order, and all numbered normal control point pairs form the normal point cloud sequence.

[0031] In the normal point cloud sequence, adjacent normal control points are connected sequentially to form an initial constraint polyline. Adjacent normal control points are pairs of normally control points with adjacent numbers in the normal point cloud sequence. When connecting, the outer plate neutral surface control point from each pair is selected, and a straight line segment connects the two adjacent outer plate neutral surface control points. All straight line segments between adjacent outer plate neutral surface control points are connected sequentially to form the initial constraint polyline.

[0032] The initial constraint polyline is projected onto the hull baseline plane to obtain the projected polyline. The projection direction is perpendicular to the hull baseline plane. Each outer plate neutral surface control point in the initial constraint polyline is projected onto the hull baseline plane along a direction perpendicular to the hull baseline plane to obtain the inflection points of the projected polyline. Each inflection point of the projected polyline is associated with a corresponding normal control point. Each inflection point of the projected polyline corresponds to an outer plate neutral surface control point aligned with a normal control point, and also corresponds to a projection foot point.

[0033] The arc length and the polygonal angle between adjacent normal control points are used as smooth transition parameters. The arc length is the length of the arc along the outer plate surface between two adjacent neutral surface control points. The arc length is calculated as follows: on the outer plate surface, using the parameter interval of the outer plate surface where the two adjacent neutral surface control points are located as the integration interval, perform curve integration on the first basic form of the outer plate surface within the parameter interval to obtain the arc length value. The polygonal angle is the angle between two adjacent polygonal segments at the inflection point in the projected polygonal line. The formula for calculating the polygonal angle is:

[0034] in , indicating the first in the projected polyline The angle between two adjacent line segments at each inflection point The inflection point number in the projected polyline; Indicates the projection polyline consisting of the first... The fold point points to the first A vector with inflection points Within the baseline plane of the hull; Indicates the projection polyline consisting of the first... The fold point points to the first A vector with inflection points Within the baseline plane of the hull; This represents the vector dot product operation; Representing vectors The modulus of the vector Length; Representing vectors The modulus of the vector Length; This represents the inverse cosine function. At the inflection point, the two adjacent line segments are the first... From the first inflection point to the... The broken line segment at the inflection point and the first inflection point From the first inflection point to the... A broken line segment with a fold inflection point. The included angle of the broken line. The value range is 0 to radian. The value range is from 2 to integers, This represents the total number of inflection points of the projected polyline.

[0035] The initial constraint polyline is smoothed according to the smoothing transition parameters to obtain the surface normal constraint line. The smoothing method involves performing cubic spline interpolation on the coordinates of all inflection points in the initial constraint polyline. The nodes of the cubic spline interpolation are the inflection points of the projected polyline, and the interpolation curve passes through each inflection point. In the construction of the cubic spline interpolation, the arc length between adjacent normal control points and the included angle of the polyline are used as constraints, ensuring that the length of the curve segment between adjacent inflection points is proportional to the arc length between adjacent normal control points, and that the turning angle of the interpolation curve at the inflection point satisfies a linear mapping relationship with the included angle of the polyline. The cubic spline curve satisfying the constraints serves as the surface normal constraint line. The surface normal constraint line is a three-dimensional spatial curve that passes through all the neutral surface control points of the outer plate.

[0036] Points on the surface normal constraint line are extended to the top surface of the jig along the opposite direction of the outer plate surface normal. Each point on the surface normal constraint line is a discrete sampling point on the surface normal constraint line, and the sampling density of the discrete sampling points is consistent with the density of the normal control point pairs in the normal point cloud sequence. The opposite direction of the outer plate surface normal is the direction in which the outer plate surface normal points towards the internal space of the hull. When extending to the top surface of the jig, a ray is drawn from each discrete sampling point on the surface normal constraint line along the opposite direction of the outer plate surface normal, and the intersection of the ray and the top surface of the jig is obtained to obtain the extension point. The top surface of the jig is the theoretical support surface formed at the top of the jig support structure, and the initial position of the top surface of the jig is determined by the set height value in the normal construction control coordinate system. The vertical height of each extension point is extracted; the vertical height is the vertical coordinate value of the extension point in the normal construction control coordinate system. The vertical heights are arranged according to the direction of the projection polyline, which is the order of the projection polyline from the first end to the second end of the curvature slat. The arranged vertical heights form a frame support height sequence. Each vertical height value in the frame support height sequence corresponds to a normal control point pair, a projection foot point, and a turning point of a projection polyline.

[0037] See Figure 4In the figure, the horizontal axis represents the inflection point number of the projected polyline, ranging from 0 to approximately 500, and the vertical axis represents the vertical height in millimeters. The figure uses different curves and scatter points to represent the vertical height distribution of key data. Gray scatter points represent the vertical coordinates of the control points on the neutral surface of the outer plate, reflecting the actual positions of the control points on the curved surface of the outer plate according to the curvature slat theory. Green dashed lines represent the vertical coordinates of the projection foot points, with values ​​always close to zero, indicating that the projection foot points are located on the established hull baseline plane. Red dotted lines represent the vertical height of the initial constraint polyline, based on the straight-line connection of adjacent neutral surface control points of the outer plate, exhibiting a stepped fluctuation, reflecting the initial discrete characteristics of the curvature slat outer plate profile. Blue dashed lines represent the vertical height of the surface normal constraint lines, which, after cubic spline interpolation smoothing, have a smooth and continuous curve, well fitting the height trend of the control points on the neutral surface of the outer plate, ensuring a natural transition between adjacent normal control points. The solid black line represents the height sequence of the jig support. The overall curve closely follows the normal constraint line of the curved surface, indicating that the support height of the jig matches the design curved surface well, ensuring accurate adjustment of the curvature slats' attitude during hoisting and support. The curve exhibits a wave-like change of first rising, then falling, and then slightly rising again, which conforms to the spatial characteristics of the complex curvature changes of the bow section's outer plate.

[0038] In practice, each elevation value in the jig support elevation sequence is assigned to the corresponding jig lifting cylinder, generating a lifting cylinder stroke command. The jig lifting cylinders are positioned on the jig foundation, and each cylinder has a horizontal position coordinate in the normal construction control coordinate system. Each elevation value in the jig support elevation sequence is matched with the horizontal position of the jig lifting cylinder according to the projection line direction. The matching method is as follows: take the horizontal coordinate of the projection foot point corresponding to an elevation value in the jig support elevation sequence, find the center point of the jig lifting cylinder that is horizontally closest to the projection foot point's horizontal coordinate, and assign the elevation value to the nearest jig lifting cylinder. After all elevation values ​​are assigned, a target elevation value is generated for each jig lifting cylinder.

[0039] In some embodiments, a lifting cylinder stroke command is generated based on the target elevation value, and the calculation formula for the stroke command is as follows:

[0040] in, Indicates the first The stroke command value of the lifting cylinder of the tire frame. This refers to the serial number of the hydraulic cylinder used for lifting the tire frame; This indicates that the high-order sequence of the tire frame support is assigned to the first... The elevation value of the lifting cylinder of the tire frame; Indicates the first The zero-position reference height of the lifting cylinder of the tire carrier. The zero-position reference height of each jig lifting cylinder is determined by the jig installation reference plane. After the jig is installed, the vertical coordinates of the top center of each jig lifting cylinder in the zero-position state are calibrated using a total station. The calibrated vertical coordinates are used as... .when When it is positive, the first The tire frame lifting cylinder lifts upwards when When it is negative, the first The hydraulic cylinder for lifting the tire frame lowers downwards.

[0041] The lifting height of each jig lifting cylinder is adjusted according to the stroke command. The stroke command value is sent to the controller of each jig lifting cylinder, and the controller drives the hydraulic circuit to change the lifting height of each jig lifting cylinder according to the corresponding stroke command value. After all jig lifting cylinders have completed their operation, the actual elevation of the top surface of each jig lifting cylinder is re-measured using a level. When the difference between the measured elevation and the target elevation exceeds the set threshold, the corresponding jig lifting cylinder is fine-tuned. The set threshold is ±1 mm.

[0042] A set of wooden blocks, matching the curvature of the outer plate of the curvature slat, is installed on the top surface of the lifting cylinder of the jig frame. The wooden block set consists of multiple stacked wooden blocks. The curvature matching method is as follows: the local radius of curvature and normal of the outer plate surface of the curvature slat at each support point are obtained, and the height and upper surface inclination angle of the wooden block set are determined based on these local radii and normals. The upper surface of each wooden block set forms a supporting curved surface that partially conforms to the outer plate surface of the curvature slat.

[0043] Hoist the curvature slats onto the wooden blocks. During hoisting, use lifting equipment to lift the curvature slats from their flat position and move them above the jig. Slowly lower the curvature slats so that the outer surface of the curvature slats contacts the upper surface of each wooden block.

[0044] Positioning reference points are set at the four corners of the curvature slab. These four corners are the points where the curvature slab's boundary lines intersect pairwise. Positioning reference points are established at these four corners using either punching holes or by installing reflectors. These positioning reference points are used for total station measurements.

[0045] Use a total station to measure the actual coordinates of the positioning reference point. Set up the total station on a known control point in the normal construction control coordinate system, backsight another known control point to complete the orientation, and then measure the three-dimensional coordinates of the positioning reference point at each of the four corner points of the curvature slab to obtain the actual coordinates.

[0046] The actual coordinates are mapped to the coordinates of the corresponding normal control points on the surface normal constraint line. The corresponding normal control points on the surface normal constraint line are the outer plate neutral surface control points in the normal control point pair corresponding to the four corner points of the curvature slat. The mapping method is as follows: find the normal control point pair closest to the four corner points of the curvature slat in the normal point cloud sequence, and take the coordinates of the outer plate neutral surface control point in the normal control point pair as the corresponding coordinates. The actual coordinates are compared with the corresponding coordinates to obtain the deviation values ​​in the three coordinate directions.

[0047] Adjust the stroke of the jig lifting cylinder and the height of the local shims in the shim group to ensure the outer surface of the curvature slats conforms to the normal constraint line of the curved surface. During adjustment, calculate the required vertical height adjustment at each corner point based on the coordinate deviation of the four corner positioning reference points, and distribute the vertical height adjustment amount to the stroke of the corresponding jig lifting cylinder. Simultaneously, for locations where the upper surface inclination of the shim group does not adequately conform to the local curved surface of the outer plate, correct the support angle by increasing or decreasing the height of the local shims. Repeat the measurement and adjustment until the deviation between the actual coordinates of the four corner positioning reference points and the coordinates of the corresponding normal control points is less than ±1 mm. At this point, the outer surface of the curvature slats conforms to the normal constraint line of the curved surface.

[0048] Select paired normal control points at the same rib position on both sides of the joint of adjacent curvature slats. The joint is the butt joint between adjacent curvature slats, and the same rib position is the location where the rib lines on the curvature slats on both sides of the joint are at the same position. Select one normal control point on each curvature slat on both sides of the joint, and the two normal control points are located at the same rib line to form a pair of normal control points.

[0049] The normal control point on the side of the preceding curvature slat in a pair of normal control points is designated as the fixed point. The preceding curvature slat is the curvature slat that has undergone attitude adjustment and is in a fixed position, while the following curvature slat is the curvature slat that needs to be aligned with the fixed point as a reference. The coordinates of the fixed point are the coordinates of the outer plate neutral surface control point of the pair of normal control points on the side of the preceding curvature slat.

[0050] Adjust the support height of the rear curvature slat at the corresponding position in the jig support height sequence so that the normal control point on one side of the rear curvature slat coincides with the fixed point. The normal control point on one side of the rear curvature slat is the outer plate neutral surface control point aligned with the corresponding normal control point on the rear curvature slat at the same rib position. The support height at the corresponding position is the elevation value corresponding to the jig lifting cylinder stroke command of the normal control point on one side of the rear curvature slat. The adjustment method is as follows: calculate the coordinate difference between the normal control point on one side of the rear curvature slat and the fixed point, calculate the vertical height adjustment amount based on the vertical component in the coordinate difference, adjust the stroke of the corresponding jig lifting cylinder, and simultaneously adjust the local shim height in the shim group until the normal control point on one side of the rear curvature slat coincides with the fixed point in space.

[0051] Ceramic gaskets are arranged at equal intervals along the joint direction within the overlapping joint area. The ceramic gaskets are elongated welded gaskets, and the spacing between them is the net distance between two adjacent ceramic gaskets, taken as 5 cm. The thickness direction of the ceramic gaskets is perpendicular to the outer surface of the plates on both sides of the joint. When arranging the ceramic gaskets, the bottom surface of the gaskets is placed against the root of the joint, so that the length direction of the ceramic gaskets is along the joint direction, and the thickness direction is the average normal direction of the outer surface of the plates on both sides of the joint.

[0052] Temporary constraints are applied to the paired normal control points that have achieved overlap. The temporary constraint method is as follows: temporary clamps are installed across the joint on both sides of the paired normal control points, and the temporary clamps are clamped to the edges of the curvature strips on both sides of the joint by bolts. The temporary constraints keep the paired normal control points in an overlapped state.

[0053] Repeat the process by selecting the paired normal control points at the next rib position until all normal control points of adjacent curvature slats are aligned. The paired normal control points at the next rib position are selected in the order from bottom to top along the joint direction. Repeat the setting of fixed points, adjustment of subsequent curvature slat support height, arrangement of ceramic pads, and application of temporary constraints until all paired normal control points along the entire length of the joint are aligned.

[0054] See Figure 5 In the diagram, the horizontal axis represents the serial number of the tire carrier lifting cylinder, the left side of the vertical axis represents the height value of the tire carrier lifting cylinder (in millimeters), and the right side of the vertical axis represents the vertical deviation of the positioning reference point (in millimeters). The solid black line curve represents the changing trend of the target elevation value of the tire carrier lifting cylinder. The target elevation value gradually increases with the serial number of the tire carrier lifting cylinder, rising steadily from about 500 mm to nearly 3000 mm. The curve shows a smooth and continuous upward trend, reflecting the design feature of the tire carrier support height gradually increasing from the low end to the high end. The dashed red line represents the zero-position reference height of the tire carrier lifting cylinder, which remains at a constant level of about 500 mm, serving as the reference value for calculating the stroke of the tire carrier lifting cylinder.

[0055] The blue dashed line represents the actual measured elevation of the jig lifting cylinder. The overall trend closely matches the black target elevation curve, and they overlap frequently, indicating that the actual execution effect of the lifting cylinder height adjustment highly meets design expectations. The measured value curve is smooth, without any significant abnormal fluctuations deviating from the target elevation, verifying the effectiveness of precisely controlling the lifting height of the jig lifting cylinder through stroke commands.

[0056] The purple triangular dots represent the vertical deviation of the positioning reference point, with a numerical distribution range of approximately ±1 mm. The distribution is random, without any obvious trend or shift, and the deviation is controlled within the set threshold of ±1 mm, meeting the stringent requirements for positioning accuracy. This deviation data reflects the level of deviation between the actual coordinates of the four corner points of the curvature slat and the coordinates of the corresponding normal control points, indicating that the actual position of the positioning reference point is highly consistent with the desired position, ensuring accurate attitude adjustment of the curvature slat on the jig.

[0057] In practice, the joint is divided into multiple tack weld sections from the lower end to the upper end of the bow section outer plating. The lower end of the joint is the end of the joint on the bow section outer plating closest to the bottom baseline, and the upper end is the end of the joint on the bow section outer plating closest to the deck edge line. The rib spacing is the distance between adjacent rib lines. Each tack weld section contains at least two rib spacings. During division, the total length of the joint along its length is obtained, and the spacing between adjacent ribs is also obtained. Using two adjacent rib spacings as the standard tack weld section length, multiple tack weld sections are sequentially cut upwards along the joint centerline from the lower end of the joint, according to the standard tack weld section length. The portion at the top that is less than two adjacent rib spacings is incorporated into the adjacent tack weld section above it.

[0058] In some embodiments, tack welds and shims are alternately arranged along the joint centerline within each tack weld section. A tack weld is a position for spot welding along the joint centerline, and a shim is a plate-shaped auxiliary connector that spans the curved strips on both sides of the joint. The joint centerline is the central curve formed when adjacent curved strips meet at the joint. Tack welds and shims are alternately arranged along the joint centerline within the tack weld section, with one shim between adjacent tack welds and one tack weld between adjacent shims. The spacing between tack welds is one rib spacing. The width of the shim extends across the joint centerline, and both ends of the shim abut against the outer surfaces of the curved strips on both sides of the joint.

[0059] For the current tack weld section, first weld the tack weld point located in the middle of the current tack weld section, then weld the tack weld points at both ends of the current tack weld section. The current tack weld section is the tack weld section currently being welded. The tack weld point in the middle of the current tack weld section is the tack weld point near the midpoint of the current tack weld section's length. The tack weld points at both ends of the current tack weld section are the tack weld points near the lower and upper ends of the current tack weld section's length. The welding sequence is as follows: first, complete the tack weld at the midpoint of the current tack weld section's length, then complete the tack weld at the lower end of the current tack weld section, and finally complete the tack weld at the upper end of the current tack weld section.

[0060] After each welding section is completed, the current coordinates of the normal control points on both sides of the joint in the current locating weld section are collected. The normal control points on both sides of the joint are the outer plate neutral surface control points among the paired normal control points located on both sides of the joint on adjacent curvature strips. The data collection method is as follows: using a total station, the three-dimensional coordinates of the normal control points on both sides of the joint in the current locating weld section are measured point by point in the normal construction control coordinate system to obtain the current coordinates.

[0061] The current coordinates are converted into a correction amount for the corresponding support elevation in the jig support elevation sequence. The correction amount is calculated as follows: For each normal control point within the current tack weld section, based on its number in the normal point cloud sequence, the corresponding support elevation is found in the jig support elevation sequence. The difference between the vertical coordinate of the current coordinates of the normal control point and its corresponding support elevation in the jig support elevation sequence is taken to obtain the support elevation correction amount for that normal control point. The formula for calculating the support elevation correction amount is:

[0062] in, Indicates the number of the current tack weld section. The support elevation correction amount corresponding to each normal control point This refers to the sequence number of the normal control point within the current tack welding section; Indicates the number of the current tack weld section. The vertical coordinates of the current coordinates of each normal control point; Indicates the number of the current tack weld section. The support elevation corresponding to each normal control point in the support height sequence of the jig support. A positive value indicates that the current vertical coordinate of the normal control point is higher than the corresponding support elevation in the jig support height program. A negative value indicates that the current vertical coordinate of the normal control point is lower than the corresponding support elevation in the jig support height program.

[0063] The corrected support elevation is used as the constraint value for the next tack weld segment. The corrected support elevation is obtained by subtracting the correction amount of the support elevation corresponding to the normal control point within the current tack weld segment from the original support elevation. The next tack weld segment is the adjacent tack weld segment above the current tack weld segment along the joint direction. The corrected support elevation replaces the corresponding support elevation in the jig support elevation sequence and is used as the support elevation constraint value for welding the next tack weld segment. Welding of all tack weld segments is completed sequentially. After the current tack weld segment is welded and the support elevation is corrected, the next tack weld segment is welded in the same way until all tack weld segments above the joint are completed.

[0064] After all tack welding sections are completed, sampling positions are determined along the joint length according to the spacing between adjacent ribs. The joint length is the direction from the bottom to the top along the joint centerline. The spacing between adjacent ribs is the distance between adjacent ribs as indicated on the hull structure drawings. Sampling positions are taken at every other rib spacing along the joint centerline, starting from the bottom of the joint and continuing at every other rib spacing until the top of the joint.

[0065] The actual coordinates of the normal control points on both sides of the joint were collected at the sampling location. These normal control points are the neutral surface control points of the outer plate among the paired normal control points arranged on the curved slats on both sides of the joint at each sampling location. The three-dimensional coordinates of the normal control points on both sides of the joint at the sampling location were measured point by point in the normal construction control coordinate system using a total station to obtain the actual coordinates.

[0066] The actual coordinates of the same normal control point are matched with the corresponding support elevation in the jig support elevation sequence. The same normal control point is the normal control point in the normal point cloud sequence corresponding to the actual coordinate acquisition point. The matching method is as follows: based on the number of the normal control point in the normal point cloud sequence, find the support elevation value corresponding to the normal control point number in the jig support elevation sequence. Determine the support elevation compensation amount corresponding to the normal control point. The support elevation compensation amount is the difference between the vertical coordinate of the actual coordinates of the normal control point and the corresponding support elevation in the jig support elevation sequence. When re-acquiring the actual coordinates after overall tack welding, the calculation method for the support elevation compensation amount is the same as the calculation method for the support elevation correction amount within the current tack welding section, that is, the support elevation compensation amount is equal to the actual vertical coordinate of the normal control point minus the corresponding support elevation in the jig support elevation sequence.

[0067] The support elevation in the jig support elevation sequence is reverse-corrected based on the support elevation compensation. The reverse correction method is as follows: subtract the support elevation compensation from the corresponding support elevation in the jig support elevation sequence to obtain the corrected support elevation. After the support elevation compensation at all sampling locations has been reverse-corrected, the corrected jig support elevation sequence is generated. In the corrected jig support elevation sequence, the support elevation remains unchanged except for the support elevation corresponding to the joint area.

[0068] The revised jig support height program is sent to the jig lifting cylinders. The sending method is as follows: each elevation value in the revised jig support height program is re-matched to the corresponding jig lifting cylinder, generating a revised lifting cylinder stroke command. After receiving the stroke command, each jig lifting cylinder adjusts the support height corresponding to the joint area according to the revised jig support height program. The support height corresponding to the joint area is the top elevation of the jig lifting cylinders at the joint of the curved slats on both sides of the joint and the corresponding wooden blocks. After adjustment, the actual vertical coordinates of the normal control points on both sides of the joint are consistent with the corresponding support elevation in the revised jig support height program.

[0069] In specific implementation, please refer to Figure 3 After the frame support height sequence is updated, a re-measurement grid is arranged on the outer plate surface of the bow section outer plating according to the rib positions and longitudinal girder spacing. Rib lines and longitudinal girder lines are extracted from the hull structure drawings and projected onto the outer plate surface along the normal direction of the bow section outer plating, resulting in rib projection lines and longitudinal girder projection lines. The intersection points formed by the rib projection lines and longitudinal girder projection lines on the outer plate surface are used as re-measurement grid nodes. The re-measurement grid nodes cover the entire area of ​​the bow section outer plating.

[0070] In some embodiments, the actual coordinates of each node of the remeasurement grid are collected, and the normal vector of the outer plate surface at each node is obtained. When collecting the actual coordinates of each node of the remeasurement grid, a total station is used to measure the three-dimensional coordinates of the remeasurement grid nodes point by point in the normal construction control coordinate system to obtain the actual coordinates. When obtaining the normal vector of the outer plate surface at each node, a three-dimensional laser scanner is used to scan the outer plate surface area adjacent to the remeasurement grid node to obtain the point cloud data of the outer plate surface adjacent to the remeasurement grid node; local tangent plane fitting is performed on the point cloud data of the outer plate surface adjacent to the remeasurement grid node. The fitting method is as follows: taking the remeasurement grid node as the center, the neighborhood radius is determined by the outer plate curvature radius and the remeasurement grid node spacing, and the local tangent plane is obtained by least squares plane fitting. The unit normal vector of the local tangent plane is used as the normal vector of the outer plate surface at the remeasurement grid node.

[0071] Spatially register the normal vector with the design outer plate normal corresponding to the measured grid node. The design outer plate normal corresponding to the measured grid node is determined by the normal direction of the theoretical outer plate surface at the corresponding parameter position of the measured grid node. The theoretical outer plate surface is the outer plate surface generated by surface interpolation from the design profile of the bow segment outer plate. The design outer plate normal vector is the normalized surface normal vector. During spatial registration, for each measured grid node, calculate the angle between the measured outer plate surface normal vector and the design outer plate normal vector.

[0072] The formula for calculating the normal deviation angle is:

[0073] in, Indicates the first The normal deviation angle of each retested grid node, in radians; This refers to the node number of the retested grid, with a value ranging from 1 to... , This represents the total number of grid nodes in the retest. Indicates the first The measured normal vector of the outer plate surface at each remeasured grid node is a three-dimensional unit vector; Indicates the first The design outer plate normal vector corresponding to each retested grid node is a three-dimensional unit vector. This represents the vector dot product operation; Representing vectors The model; Representing vectors The model; This represents the inverse cosine function. When... When the value is 0, the measured normal vector of the outer plate coincides with the designed normal vector of the outer plate; when... When the value increases, the deviation between the measured normal vector of the outer plate surface and the designed normal vector of the outer plate increases.

[0074] The normal deviation angles of all remeasured grid nodes are arranged according to their positions on the outer plate of the bow section, forming the normal vector distribution of the outer plate surface.

[0075] Based on the distribution of the normal vector on the outer plate surface, adjust the local support elevation in the jig support elevation sequence to ensure that the distribution of the normal vector on the outer plate surface is orthogonal to the theoretical outer plate surface. When adjusting the local support elevation, determine the position of the jig lifting cylinder or wooden block group corresponding to each remeasured grid node. Based on the normal deviation angle at the remeasured grid node and the direction of the measured normal vector on the outer plate surface, calculate the vertical height that needs to be corrected at the remeasured grid node. If the normal deviation angle is positive and the measured normal vector on the outer plate surface is biased towards the outside of the hull, decrease the corresponding local support elevation; if the normal deviation angle is negative and the measured normal vector on the outer plate surface is biased towards the inside of the hull, increase the corresponding local support elevation. Modify the corresponding values ​​in the jig support elevation sequence and send the corrected jig support elevation sequence to the jig lifting cylinder for adjustment. Repeatedly collect the actual coordinates and normal vectors of the remeasured grid nodes and calculate the normal deviation angle until the normal deviation angle values ​​of all remeasured grid nodes are less than the set threshold. The threshold value is determined by the allowable value of the normal deviation of the outer plate in the construction accuracy standard.

[0076] During the orthogonal state maintenance period, the formal welding of the curved slat joints and the treatment of weld reinforcement are completed sequentially. The formal welding is performed according to the welding procedure specification, and the welding sequence is symmetrical from the bottom end of the joint to the top end. After the root pass welding is completed, the filler weld and the cover weld are performed. The treatment of weld reinforcement involves grinding the weld metal that exceeds the design surface height of the outer plate after the formal welding is completed, so that the weld reinforcement meets the surface flatness requirements of the outer plate.

[0077] Finally, the bow section outer plate was obtained from the normal construction.

[0078] See Figure 6 In the figure, the horizontal axis represents the serial number of the re-measured grid node, covering the entire area of ​​the bow section's outer plate, and the vertical axis represents the normal deviation angle of the outer plate surface, in radians. Blue dots represent the normal deviation angles at each re-measured grid node before adjustment; these blue dots are generally distributed within the range of 0.01 to 0.06 radians, indicating a large and highly discrete normal deviation of the outer plate surface before adjustment. Red squares represent the normal deviation angles at each re-measured grid node after adjustment; these red squares are mainly concentrated between 0 and 0.01 radians, and are generally significantly lower than the values ​​before adjustment, indicating that adjusting the jig support height sequence significantly reduced the normal deviation of the outer plate surface.

[0079] The black dashed line in the figure represents the threshold value for the normal deviation angle, which is approximately 0.008 radians. This threshold serves as the allowable limit for the normal deviation of the outer panel surface. After adjustment, most of the red data points are below this threshold, indicating that the overall normal deviation of the outer panel surface meets the construction accuracy requirements. The green solid line represents the distribution curve of the normal vector of the outer panel surface. This curve exhibits small fluctuations and a stable overall trend, further reflecting the good match between the adjusted outer panel surface normal and the design normal.

[0080] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method of normal construction of a hull bow section of a ship, characterized in that, include: Based on the design lines of the bow section outer plating, a normal construction control coordinate system is established on the hull baseline plane. The normal construction control coordinate system uses the hull centerline plane and the hull baseline plane as coordinate reference planes, and divides the bow section outer plating into multiple curvature strips. The theoretical outer surface of each curvature slab is discretized into several normal control points, generating a normal point cloud sequence for each curvature slab. Construct surface normal constraint lines using adjacent normal control points in the normal point cloud sequence, calculate the smooth transition parameters between the surface normal constraint lines, and generate a jig support height sequence, including: In the normal point cloud sequence, adjacent normal control points are connected sequentially to form an initial constraint polyline; The initial constraint polyline is projected onto the hull baseline plane to obtain the projected polyline, and each inflection point of the projected polyline is associated with the corresponding normal control point. Using the arc length and the included angle of the polyline between adjacent normal control points as the smoothing transition parameters, the initial constraint polyline is smoothed according to the smoothing transition parameters to obtain the surface normal constraint line; Extend each point on the surface normal constraint line to the top surface of the jig along the opposite direction of the outer plate surface normal, extract the vertical height of each extension point, arrange the vertical heights according to the direction of the projection broken line, and generate the jig support height sequence. The jig is arranged according to the jig support height sequence. The curvature strip is hoisted onto the jig. The attitude of the curvature strip is adjusted with the surface normal constraint line as a reference so that the normal control points of adjacent curvature strips are aligned. Position welding is performed at the joint of the curvature slats. After positioning welding, the actual coordinates of the normal control points on both sides of the joint are re-acquired, and the height sequence of the jig support is updated to complete the normal construction of the bow section outer plate.

2. A method of normal construction of a hull bow section of a ship according to claim 1, characterized in that, The method of dividing the bow section outer plate into multiple curvature strips includes: Using the bow column angle line in the design profile of the bow section outer plate as the starting boundary, initial dividing lines are generated at equal arc length intervals along the direction of the maximum longitudinal curvature gradient of the outer plate. A geometric check is performed on the slat area enclosed by the initial dividing line and the outer plate boundary. When the initial dividing line passes through the elbow plate seat or manhole on the outer plate, the initial dividing line is reoriented along the edge of the elbow plate seat or manhole to obtain the actual dividing line. The actual dividing lines are mapped onto the outer plate surface, and each curvature slat is numbered according to the direction of the actual dividing lines to generate the plurality of curvature slats.

3. A method of normal construction of a hull bow section according to claim 1, characterized in that, The process of discretizing the theoretical outer surface of each curvature slab into several normal control points to generate a normal point cloud sequence for each curvature slab includes: Sampling grids are arranged on the theoretical outer plate surface of each curvature slat according to the rib spacing and longitudinal rib spacing, and the nodes of the sampling grids are used as candidate control points. Draw a normal line to the outer plate surface through each candidate control point, mark the intersection of the normal line and the hull baseline plane as the projection foot point, and translate the candidate control point along the normal line to the outside of the outer plate by a plate thickness distance to obtain the outer plate neutral surface control point; The neutral surface control points of the outer plate are paired with the corresponding projection foot points to form normal control point pairs. All normal control point pairs are arranged in the longitudinal order of the curvature strips to generate the normal point cloud sequence.

4. A method of normal construction of a hull bow section according to claim 1, characterized in that, The step of arranging the jig according to the jig support height sequence, hoisting the curvature slats onto the jig, and adjusting the attitude of the curvature slats with the surface normal constraint line as a reference includes: Each elevation value in the jig support elevation sequence is assigned to the corresponding jig lifting cylinder to generate a lifting cylinder stroke command. Adjust the lifting height of each jig lifting cylinder according to the stroke command, and install a set of wooden blocks on the top surface of the jig that matches the curvature of the outer plate of the curvature strip; The curvature strip is hoisted onto the wooden block assembly, and positioning reference points are set at the four corners of the curvature strip; The actual coordinates of the positioning reference point are measured using a total station. The actual coordinates are then compared with the coordinates of the corresponding normal control point on the surface normal constraint line. The stroke of the lifting cylinder of the jig and the height of the local pads in the pad group are adjusted so that the outer surface of the curvature strip is in contact with the surface normal constraint line.

5. A method of normal construction of a hull bow section of a ship according to claim 1, characterized in that, Aligning the normal control points of adjacent curvature slats includes: Select paired normal control points at the same rib position on both sides of the joint of adjacent curvature strips; Using the normal control point on the side of the preceding curvature strip as a fixed point, the support height of the following curvature strip at the corresponding position in the frame support height sequence is adjusted so that the normal control point on the side of the following curvature strip coincides with the fixed point. Ceramic pads are arranged at equal intervals along the joint direction within the overlapping joint area, and the thickness direction of the ceramic pads is perpendicular to the outer plate surface on both sides of the joint. Apply temporary constraints to the pairs of normal control points that have completed the overlap, and then select the pairs of normal control points at the next rib position to repeat the operation until all normal control points of adjacent curvature slats are aligned.

6. The normal construction method for the bow section outer plating of a ship according to claim 1, characterized in that, The aforementioned tack welding at the joint of the curved strip includes: The joint is divided into multiple tack weld sections from the lower end to the upper end of the bow section outer plate, and each tack weld section contains at least two rib spacings. In each tack welding section, tack welding points and saddle plates are alternately arranged along the center line of the joint, and the saddle plates are straddled on the curved strips on both sides of the joint; First, weld the locating weld point located in the middle of the current locating weld section, and then weld the locating weld points at both ends of the section. After each tack welding section is completed, the current coordinates of the normal control points on both sides of the joint of that section are collected, and the current coordinates are converted into the correction amount of the corresponding support elevation in the jig support elevation program sequence. The corrected support elevation is used as the constraint value for the next tack weld section, and the welding of all tack weld sections is completed in sequence.

7. The normal construction method for the bow section outer plating of a ship according to claim 1, characterized in that, The process of re-acquiring the actual coordinates of the normal control points on both sides of the joint after the positioning weld and updating the jig support height program column includes: The sampling position is determined along the length of the joint according to the spacing between adjacent ribs, and the actual coordinates of the normal control points on both sides of the joint are collected at the sampling position. Match the actual coordinates of the same normal control point with the corresponding support elevation of the normal control point in the support elevation sequence of the jig support to determine the support elevation compensation amount corresponding to the normal control point. Based on the support elevation compensation amount, the corresponding support elevation in the jig support elevation program sequence is reversed to generate the corrected jig support elevation program sequence. The modified jig support height program is sent to the jig lifting cylinder, so that the jig lifting cylinder adjusts the support height corresponding to the joint area according to the modified jig support height program.

8. The normal construction method for the bow section outer plating of a ship according to claim 1, characterized in that, The completion of the normal construction of the bow section outer plate includes: After the update of the high program sequence of the frame support is completed, a re-measurement grid is arranged on the outer plate surface of the bow section outer plate according to the rib position and longitudinal rib spacing; Collect the actual coordinates of each node of the retest grid and obtain the normal vector of the outer plate surface at each node; The normal vector is spatially registered with the design outer plate normal corresponding to the node to obtain the distribution of the outer plate surface normal vector; Based on the distribution of the normal vector of the outer plate surface, adjust the local support elevation in the support height sequence of the jig frame so that the distribution of the normal vector of the outer plate surface is orthogonal to the theoretical outer plate surface. During the period of maintaining the orthogonal state, the formal welding of the curvature slat joints and the treatment of the weld reinforcement are completed in sequence to obtain the bow section outer plate of normal construction.

9. The normal construction method for the bow section outer plating of a ship according to claim 1, characterized in that, The establishment of a normal construction control coordinate system on the hull baseline plane based on the design lines of the bow section outer plating includes: Extract the bow outline, deck edge line, and outer plate development line from the design profile of the bow section outer plate, and then divide the outer plate development line into layers according to the design waterline interval; The intersection of the hull centerline plane and the hull baseline plane is taken as the longitudinal reference axis, and the intersection of the longitudinal reference axis and the bow perpendicular is taken as the origin of the coordinate system. Establish the normal construction control coordinate system at the origin of the coordinate system, make the horizontal plane of the normal construction control coordinate system coincide with the baseline plane of the hull, make the longitudinal axis of the normal construction control coordinate system point to the stern along the longitudinal reference axis, and make the transverse axis of the normal construction control coordinate system perpendicular to the centerline plane of the hull. The shape value points on the outer plate development line are converted to the normal construction control coordinate system, and the converted shape value points are used as the dividing boundary of the multiple curvature strips.

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