A lofting method for a thin film type LNG liquefied gas ship liquid dome segmented inner shell plate

Abstract

The application discloses a lofting method for a thin film type LNG liquefied gas ship liquid dome segmented inner shell plate, which comprises the following steps: drawing an initial inner shell plate in CAD drawing software according to the length and width dimensions of the actual inner shell plate after butt welding; correcting the boundary of the initial inner shell plate and all the hole positions on the plate according to the actual opening data of the liquid dome inner deck to obtain an inner shell plate drawing; and converting lofting data and generating lofting data according to the drawn inner shell plate drawing, marking and cutting the actual inner shell plate, effectively improving the marking and cutting precision, and ensuring that the size of the cut inner shell plate matches the actual opening of the liquid dome inner deck, the hole position on the inner shell plate is aligned with the position of the pipe to be penetrated, and the bolt hole position on the inner shell plate is aligned with the positioning bolt on the insulation box, so that the inner shell plate is matched with the surrounding ship body structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of shipbuilding technology, in particular to a lofting method of a liquid dome section inner hull plate of a membrane type LNG liquefied gas ship. BACKGROUND

[0002] Each cargo hold area of the membrane type LNG liquefied gas ship is equipped with a pump tower, and the pump tower base is arranged on the cargo hold bottom plate. A plurality of pipes are connected to the pump tower, and the pipes pass through the deck from the bottom of the hold to the outside of the hold through openings on the deck, and the cargo liquefied gas is transported through the pipes for loading and unloading.

[0003] According to the installation process, a separate section, referred to as a pump tower section, needs to be drawn on the part of the deck structure through which the pipes pass, and the pump tower section is composed of an inner and outer double hull. The inner hull part is made of stainless steel, and bolt holes are opened on the stainless steel part of the pump tower section for fixing the insulation box. The pump tower section needs to be hoisted and embedded after the completion of the installation of the insulation box in the hold and the installation of the pump tower and the pipes. Due to the particularity of the pump tower section, the stainless steel part of the inner hull needs to be fitted with the surrounding parts, the opening position on the part needs to be aligned with the pipes passing through, the bolt holes on the part need to be aligned with the positioning bolts of the insulation box, and once there is a deviation, it cannot be corrected on site. SUMMARY

[0004] Therefore, the present application provides a lofting method of a liquid dome section inner hull plate of a membrane type LNG liquefied gas ship to solve the problems in the background art.

[0005] A lofting method of a liquid dome section inner hull plate of a membrane type LNG liquefied gas ship, specifically comprising the following steps:

[0006] S1, drawing an initial inner hull plate in CAD drawing software;

[0007] S2, collecting actual opening data of the inner deck of the liquid dome;

[0008] S3, determining the actual boundary of the inner hull plate on the initial inner hull plate by using the CAD point drawing function according to the actual opening data of the inner deck of the liquid dome;

[0009] Then, the actual boundary of the inner hull plate is offset by the distance of the bevel gap from the outside to the inside by using the CAD offset function, and a fillet is drawn at the four corners to obtain the actual contour of the inner hull plate;

[0010] S4, obtaining a liquid dome opening position deviation table according to the actual opening data of the inner deck of the liquid dome, and correcting the position of the standard pipe hole drawn on the inner hull plate according to the liquid dome opening position deviation table;

[0011] S5, lofting a welding bevel for the pipe hole that needs to be welded on the inner hull plate to obtain an inner hull plate CAD drawing;

[0012] S6, according to the inner shell plate CAD drawing by lofting software to generate marking and cutting instructions, marking and cutting the actual inner shell plate.

[0013] Preferably, the specific steps of drawing the initial inner shell plate in the CAD drawing software according to the theoretical design data in step S1 are:

[0014] According to the length and width dimensions of the actual inner shell plate spliced by two stainless steel plates, the inner shell plate is drawn in the CAD drawing software;

[0015] Draw the ship centerline and the rib inspection line on the inner shell plate;

[0016] According to the theoretical opening position and size of each pipe hole, draw each standard pipe hole on the inner shell plate.

[0017] Preferably, the liquid dome opening position deviation table includes the deviation value X of the pump tower base center to the rib inspection line and the deviation value Y of the pump tower base center to the ship centerline.

[0018] Preferably, the specific steps of lofting the welding bevel of the pipe hole that needs to be welded on the inner shell plate in step S5 are: for the pipe hole that needs to be welded on the inner shell plate, mark the required lofting bevel angle on the CAD drawing when it is welded and fixed with the corresponding pipe.

[0019] Preferably, the marking instructions generated in step S6 include the outer contour cutting line of the inner shell plate, the opening position marking of each pipe hole, and the bolt hole position marking,

[0020] The generated cutting instructions include the outer contour size of the inner shell plate and the opening hole diameter of each pipe hole.

[0021] Preferably, the standard pipe hole drawn on the inner shell plate in the CAD drawing is represented by a broken line to distinguish from the cutting instructions.

[0022] The beneficial effects of the present application are:

[0023] The present application draws the initial inner shell plate in the CAD drawing software according to the actual length and width dimensions of the actual inner shell plate after splicing, and then corrects the boundary of the initial inner shell plate and all the opening positions on the plate according to the actual opening data of the liquid dome inner deck, to obtain the inner shell plate drawing. According to the drawn inner shell plate drawing, lofting data conversion and lofting data generation are carried out, and the actual inner shell plate is marked and cut, which effectively improves the marking and cutting precision, ensures that the size of the cut inner shell plate matches the actual opening of the liquid dome inner deck, the opening position on the inner shell plate is aligned with the position of the pipe to be penetrated, and the bolt hole position on the inner shell plate is aligned with the positioning bolt on the insulation box, so that the inner shell plate is consistent with the surrounding ship structure, and the pump tower section is installed in place at one time. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0025] Figure 1 is the liquid dome inner deck stainless steel reference line and the theoretical opening position.

[0026] Figure 2 is the liquid dome inner deck stainless steel part opening measurement data.

[0027] Figure 3 is the liquid dome inner deck pump tower base center measurement data.

[0028] Figure 4 is the liquid dome inner deck stainless steel part scribe CAD drawing.

[0029] Figure 5 is the liquid dome inner deck stainless steel part cutting CAD drawing.

[0030] The meanings of the reference numerals in the drawings are as follows:

[0031] 1 is a first stainless steel plate, 2 is a second stainless steel plate, 3 is a pipe hole, 4 is a bolt hole position line, 5 is a ship centerline, 6 is a frame inspection line, 7 is a lofting bevel, 8 is a pump tower base center, and 9 is an opening center position line. DETAILED DESCRIPTION

[0032] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be described in detail below by means of specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0033] The terms used in the present disclosure are merely for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The singular forms "a", "said" and "the" used in the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein means and includes any or all possible combinations of one or more associated listed items.

[0034] In order to better understand the technical solutions of the present application, the present application will be described in detail below with reference to the drawings.

[0035] This invention provides a method for laying out the inner hull plate of a membrane-type LNG carrier liquid dome section, specifically including the following steps:

[0036] S1, Draw the initial inner shell plate in CAD drawing software.

[0037] Specifically, such as Figure 1 As shown, first, check the positioning information of all openings on the inner shell plate, and draw the initial outline of the inner shell plate 1 in CAD drawing software based on the actual length and width dimensions of the inner shell plate which is welded together using two stainless steel plates (first stainless steel plate 1 and second stainless steel plate 2).

[0038] Then, draw the hull centerline 5 and the rib inspection line 6 on the inner shell plate;

[0039] Then, based on the theoretical opening positions and dimensions of each opening, draw the corresponding positions of each hole on the inner shell plate 1 (including the positions of pipe hole 3 and bolt hole 4).

[0040] The pipe hole 3 drawn on the inner shell plate 1 is represented by a broken line to distinguish it from the cutting line drawn on the plate before the actual cutting.

[0041] S2, collects actual opening data of the inner deck of the liquid dome.

[0042] S3, based on the actual opening data of the inner deck of the liquid dome, use the CAD plotting function to plot points on the initial inner shell plate drawn in step S1, and correct the boundary of the inner shell plate, such as... Figure 2 As shown.

[0043] Then, using the CAD offset function, the boundary of the inner shell plate after correction is offset from the outside to the inside by the distance of the bevel gap, and rounded corners are drawn at its four corners to obtain the actual outline of the inner shell plate, as shown in Figure 2.

[0044] S4, Based on the actual opening data of the inner deck of the liquid dome, obtain the liquid dome opening position deviation table, such as... Figure 3 As shown, the initial positions of all the openings drawn on the inner shell plate are corrected according to the liquid dome opening position deviation table.

[0045] The liquid dome opening position deviation table includes the deviation value X from the pump tower base center 8 to the rib inspection line 6, and the deviation value Y from the pump tower base center 8 to the hull centerline 5.

[0046] like Figure 3As shown, for example, the theoretical value X from the pump tower base center 8 to the rib inspection line 6 should be 857mm, but the actual value X is 847mm. The theoretical value Y from the pump tower base center 8 to the hull centerline 5 is 1250mm, but the actual value Y is 1262mm. Therefore, the pump tower base center 8 deviates 10mm to the right in the X direction and 12mm upward in the Y direction compared to its theoretical position. Therefore, all openings on the inner shell plate need to be deviated 10mm to the right in the X direction and 12mm upward in the Y direction according to the offset of the pump tower base center 8. That is, the relative positions of each opening to the pump tower base center 8 and the relative positions of the openings themselves remain unchanged; only the positions of each opening are translated accordingly based on the offset of the pump tower base center 8. Figure 4 As shown.

[0047] S5, lay out the welding bevel for the pipe holes that need to be welded on the inner shell plate.

[0048] For welding bevel layout of pipe holes on the inner shell plate, it means marking on the CAD drawing the bevel angle required for welding and fixing to the corresponding pipeline (e.g., ...). Figure 5 The reference number 7 indicates the "45-degree reverse, leave 12.5" mark on the pipe hole.

[0049] The CAD drawing of the inner shell plate can be obtained by the above steps S1-S5.

[0050] S6, such as Figure 5 As shown, based on the CAD drawing of the inner shell plate, the layout software generates scribing and cutting instructions to scribing and cutting the actual inner shell plate. The starting point of the scribing and cutting instructions is the same position.

[0051] When scribing and cutting the actual inner shell plate, first scribing the opening lines on the actual inner shell plate (the opening lines on the actual inner shell plate are represented by solid lines), and then manually verifying the accuracy of the scribing before proceeding with the formal cutting.

[0052] The generated scribing instructions include cutting lines for the outer contour of the inner shell plate, scribing lines for the positions of various openings, and scribing lines for the positions of bolt holes.

[0053] The generated cutting instructions include the outer contour dimensions of the inner shell plate and the diameter of each opening.

[0054] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for laying out the inner hull plates of a membrane-type LNG carrier's liquid dome section, characterized in that, Specifically, the following steps are included: S1. The actual inner shell plate is obtained by welding two stainless steel plates together. The initial inner shell plate is drawn in CAD drawing software according to the length and width dimensions of the actual inner shell plate. S2, collect actual opening data of the inner deck of the liquid dome; S3. Based on the actual opening data of the inner deck of the liquid dome, the boundary of the initial inner shell plate is corrected using the CAD plotting function. Then, using the CAD offset function, the boundary of the inner shell plate after correction is offset from the inside to the outside by the distance of the bevel gap, and rounded corners are drawn at its four corners to obtain the actual outline of the inner shell plate. S4. Obtain the liquid dome opening position deviation table based on the actual opening data of the inner deck of the liquid dome, and correct the initial position of all openings drawn on the inner shell plate according to the liquid dome opening position deviation table. The liquid dome opening position deviation table includes the deviation value X from the pump tower base center (8) to the rib inspection line (6) and the deviation value Y from the pump tower base center (8) to the hull centerline (5). S5, lay out the welding bevel for the pipe holes that need to be welded on the inner shell plate to obtain the CAD drawing of the inner shell plate; The specific steps for laying out the welding bevel for the pipe holes that need to be welded on the inner shell plate in step S5 are as follows: For the pipe holes that need to be welded on the inner shell plate, mark the bevel angle that needs to be reserved when welding and fixing them with the corresponding pipeline on the CAD drawing. S6 generates scribing and cutting instructions based on the CAD drawing of the inner shell plate using layout software, and then scribing and cutting the actual inner shell plate.

2. The method for laying out the inner hull plate of the liquid dome section of a membrane-type LNG carrier according to claim 1, characterized in that, The specific steps in step S1 to draw the initial inner shell plate in CAD drawing software based on the actual length and width dimensions of the inner shell plate are as follows: Draw the inner shell plate in CAD drawing software according to the actual length and width dimensions of the inner shell plate (1). Draw the hull centerline (5) and rib inspection lines (6) on the inner shell plate. Draw each hole on the inner shell plate (1) according to the theoretical hole position and size of each hole.

3. The method for laying out the inner hull plate of the liquid dome section of a membrane-type LNG carrier according to claim 1, characterized in that, The scribing instructions generated in step S6 include the inner shell plate outer contour cutting line, scribing lines for each opening position, and scribing lines for the bolt hole positions. The generated cutting instructions include the outer contour dimensions of the inner shell plate and the diameter of each opening.

4. The method for laying out the inner hull plate of the liquid dome section of a membrane-type LNG carrier according to claim 1, characterized in that, In CAD drawings, the standard pipe hole (3) drawn on the inner shell plate is represented by a broken line to distinguish it from the cutting command.

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