CN106881539B - Pressure container - Google Patents

Abstract

The invention discloses a pressure vessel, which is provided with a non-centripetal connecting pipe (10), wherein the non-centripetal connecting pipe (10) is non-centripetally connected to a cylinder body (20) of the pressure vessel, the non-centripetal connecting pipe (10) is connected with the cylinder body (20) through a groove, the groove is arranged on the cylinder body (20), the cylinder body (20) is welded with the non-centripetal connecting pipe (10) through the groove, the groove is a unilateral V-shaped groove, and preferably, the distance from the upper end point on the outer side of the cylinder body of the groove to the connecting pipe is equal to the distance from the lower end point on the outer side of the cylinder body of the groove to the connecting pipe; the groove provided by the invention can effectively ensure the accuracy after gas cutting, does not damage the root of the groove, can effectively control the welding deformation and ensures the welded size of the connecting pipe.

Description

Pressure container

Technical Field

The invention relates to a pressure vessel, in particular to a pressure vessel with a non-centripetal connecting pipe.

Background

The non-centripetal connecting pipe is a common structural form in a pressure vessel product, and for a welding groove of the connecting pipe and the cylinder, after the non-centripetal connecting pipe and the cylinder are processed by a conventional welding groove, the space in at least 1/4 circumferences of the groove at the acute angle formed by the connecting pipe and the cylinder is too large, so that a great amount of welding deposited metal filling amount is increased in the welding process; and the other symmetrical side has less filling amount of welding deposited metal, so that the difference of heat input amount in the welding process of the two sides of the connecting pipe is huge, and the phenomenon is increased along with the increase of the distance between the connecting pipe and the axial center of the cylinder. Therefore, the groove form causes the following two serious problems after the non-centripetal pipe is welded with the cylinder body:

1) the connecting pipe is deformed seriously and deforms towards one side of the center of the cylinder body, so that the dislocation cannot be realized when the connecting pipe is welded with an external pipeline or is butted with a flange; if the adapter is a liquid level meter adapter of the container, the function of controlling the liquid position in the container by the adapter is failed;

2) the barrel body deforms, and if the barrel body is thin, the barrel body deforms greatly at a welding position.

Therefore, how to control the welding deformation of the non-centripetal connecting pipe and the cylinder body and ensure the position precision requirement of the connecting pipe after welding becomes a difficult problem in the manufacturing process of pressure vessel products.

For the reasons, the inventor modifies the prior art and researches a welding groove of a non-centripetal connecting pipe and a cylinder of a pressure vessel

Disclosure of Invention

In order to overcome the above problems, the present inventors have made intensive studies to design a pressure vessel in which a bevel at a junction of a non-centripetal nozzle and a bevel enables welding deposited metal filling amounts around the bevel to be substantially the same, thereby contributing to control of welding deformation.

In particular, the object of the invention is to provide a pressure vessel with a non-centripetal nozzle 10, the non-centripetal nozzle 10 being non-centripetally connected to the cylinder 20 of the pressure vessel. The non-centripetal connecting pipe 10 is connected with the cylinder 20 through a welding groove.

The groove is arranged on the cylinder body 20, the groove is a single-side V-shaped groove, and the distance from the upper end point of the outer side of the cylinder body of the groove to the connecting pipe is equal to the distance from the lower end point of the outer side of the cylinder body of the groove to the connecting pipe.

The groove is formed by cutting along a lofting line step by step, and preferably, the cutting is carried out according to the following steps:

finding the central point of the opening on the cylinder 20 to be welded, and drawing each line on the cylinder;

cutting off the walnut-shaped area 6;

the shadow area 7 is removed;

cutting off the inner side part of the opening;

the cutting removes the diagonal region 8.

The lofting line is drawn by using an auxiliary tool, the lofting line drawn, printed or engraved by the auxiliary tool comprises a hole-opening lofting line 1 and an initial centripetal hole lofting line 2, the hole-opening lofting line 1 comprises a groove inner edge line 3, a groove outer edge line 4 and an inner groove line 5, and the inner groove line 5 is an inner lofting drawing of the cylinder body;

the initial centripetal hole lofting line 2 is superposed with the central point of the groove inner edge line 3, and the superposed and crossed part of the two lines is a walnut-shaped area 6;

and the center points of the groove inner edge line 3, the groove outer edge line 4 and the walnut-shaped area 6 are superposed and combined to obtain a lofting map of the outer side of the cylinder.

The remaining portion of the inner edge line 3 of the groove, except the walnut-shaped area 6, forms a shaded area 7.

The non-overlapping portion of the groove inner edge line 3 and the groove outer edge line 4 forms a diagonal line region 8.

The invention has the advantages that:

1. the groove provided by the invention adopts a single-side V-shaped groove, the width of the groove is marked instead of marking the angle of the groove, the problem that the width of the non-centripetal connecting pipe and the local groove of the cylinder body is overlarge is avoided, and the filling amount of welding deposited metal at the periphery of the groove is basically consistent, so that the welding deformation can be effectively controlled while the welding amount is reduced, and the post-welding size of the connecting pipe is ensured;

2. the processing auxiliary tool with the proportion of 1:1 is adopted for drawing the lines of the cylinder body, and the processing auxiliary tool is simple to manufacture, convenient to operate and strong in flexibility;

3. in the invention, the groove is machined by adopting a gas cutting centripetal hole, trepanning and groove three-step gas cutting method, so that the accuracy of the gas cutting groove can be effectively ensured, the gas cutting trepanning is ensured not to damage the root of the groove, the defect of manual gas cutting rough machining is made up to a certain extent, and the machined groove meets the high requirement of pattern design;

4. according to the invention, additional machining is not needed, the groove machining cost is effectively reduced, the groove machining effect is increased, and the welding quality of the connecting pipe and the cylinder body is improved;

5. the method has the advantages of simple calculation, convenient use and wide application range, and is particularly suitable for various connecting pipes with high position precision requirements.

Drawings

FIG. 1 is a schematic view showing the connection of a non-centripetal nozzle and a cylinder according to a preferred embodiment of the present invention;

FIG. 2 shows an enlarged view of circled portion A of FIG. 1;

FIG. 3 shows a schematic diagram labeling groove width D in accordance with the present invention;

FIG. 4 shows a schematic view of a cartridge opening in accordance with a preferred embodiment of the present invention;

FIG. 5 shows a schematic view of a half arc length according to the present invention;

FIG. 6 shows a schematic of arc length according to the present invention;

FIG. 7 shows a schematic view of the quartering points of the arc length in accordance with the present invention;

FIG. 8 illustrates a schematic view of a half chord length according to a preferred embodiment of the present invention;

FIG. 9 shows a schematic view of a loft line according to a preferred embodiment of the present invention;

FIG. 10 shows a schematic view of a centripetal cutting according to a preferred embodiment of the present invention;

FIG. 11 shows a schematic view of a walnut-shaped region according to a preferred embodiment of the invention;

FIG. 12 shows a schematic view of a loft view of the outside of a cartridge in accordance with a preferred embodiment of the present invention;

FIG. 13 shows a schematic view of a loft of the inside of a can according to a preferred embodiment of the present invention;

fig. 14 shows a schematic view of a tapping process according to a preferred embodiment of the present invention.

The reference numbers indicate:

1-holing lofting line

2-initial centripetal hole lofting line

3-groove inner edge line

4-bevel outer edge line

5-inner bevel line

6-walnut shaped region

7-shaded area

8-oblique line area

9-projection aperture

10-connecting pipe

11-center point of opening hole on outer side of cylinder

12-center point of inner side opening of cylinder

13-opening of the hole

20-barrel

Detailed Description

The invention is explained in more detail below with reference to the figures and examples. The features and advantages of the present invention will become more apparent from the description.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The invention provides a pressure vessel with a non-centripetal nozzle 10, wherein in a preferred embodiment, the connection relationship between the non-centripetal nozzle 10 and a pressure vessel cylinder 20 is as shown in figure 1, and the non-centripetal nozzle 10 is preferably welded with the cylinder 20; in addition, as shown in fig. 2, in the welding operation, the V-groove angle between the connection pipe and the cylinder is conventionally marked in a pattern, and in the present invention, β only refers to the V-groove angle between the connection pipe and the cylinder, and does not have any other meaning.

In the pressure vessel provided by the invention, the non-centripetal connecting pipe 10 is connected with the cylinder 20 through the groove, the groove is arranged on the cylinder 20, the groove is a single-side V-shaped groove, and in a preferred embodiment, the distance from the upper end point of the outer side of the cylinder of the groove to the connecting pipe is equal to the distance from the lower end point of the outer side of the cylinder of the groove to the connecting pipe.

In the groove provided by the invention, the groove angle is marked instead of marking the groove width, wherein the groove width is the distance from the upper end point on the outer side of the opening of the cylinder body to the connecting pipe, or the distance from the lower end point on the outer side of the opening of the cylinder body to the connecting pipe. In the present invention, as shown in fig. 3, the groove width is represented by D, and the groove width D may be arbitrarily changed to a set value according to actual conditions.

The marked groove width D is used for replacing the marked groove angle beta, so that the calculation is convenient, the application range is wide, and the problem of overlarge width of the non-centripetal connecting pipe and the local groove of the cylinder body can be effectively avoided.

The groove provided by the invention is formed by cutting step by step, and cutting step by step is carried out along a lofting line, in a preferred embodiment, the cutting mode of the groove is gas cutting, and the gas cutting is carried out according to the following steps:

step 1') finding a central point of an opening hole on a cylinder body 20 to be welded, and drawing a lofting line on the cylinder body;

wherein the lofting line is drawn by means of an auxiliary tool. The auxiliary tool is provided with a lofting line in a drawing, printing or engraving mode, and the ratio of the auxiliary tool to the size of the opening of the cylinder to be welded is 1: 1. And, the appurtenance has certain thickness and hardness, can bend, can cut or cut wantonly.

In a preferred embodiment, the auxiliary tool may be any one of a metal sheet, a paper sheet, and a plastic sheet;

in a more preferred embodiment, the auxiliary tool is highland barley paper.

In a preferred embodiment, the auxiliary tool may be printed with any one of the lofting lines; in a more preferred embodiment, the auxiliary tool may be printed with a plurality of lines in the loft line.

In the invention, the lofting line on the auxiliary tool comprises a hole-opening lofting line 1 and an initial centripetal hole lofting line 2, wherein the hole-opening lofting line 1 comprises an inner edge line 3 of a groove, an outer edge line 4 of the groove and an inner edge line 5; wherein, the inner bevel line 5 is a lofting drawing of the inner side of the cylinder body;

in a preferred embodiment, the opening lofting line 1 is drawn according to the following steps:

A) as shown in fig. 4, an opening 13 is drawn on the cylinder 20, the opening axis is the connection pipe axis, the intersection point of the opening axis and the cylinder 20 is determined as an opening axial central point, and the opening axial central points are two, namely a cylinder outside opening central point 11 and a cylinder inside opening central point 12; determining the half arc length between the top point of the opening on the same side of the cylinder 20 and the axial center point of the opening;

in one embodiment, as shown in fig. 5, the half arc length is the length of the half arc between the apex of the barrel outside opening and the barrel outside opening center point 11;

in another embodiment, the half arc length may also be the length of the half arc between the apex of the barrel inside opening and the barrel inside opening center point 12;

in the present invention, the half arc length is represented by L2, and L2 is represented by the length of the half arc only.

B) Determining the arc length between the upper end point and the lower end point of the opening on the same side of the cylinder body 20, and determining the arc length to divide equally;

in one embodiment, as shown in fig. 6, the arc length is the length of the arc between the upper end point of the opening on the outer side of the cylinder and the lower end point of the opening on the outer side of the cylinder;

in another embodiment, the arc length can also be the length of an arc between the upper end point of the opening on the inner side of the cylinder and the lower end point of the opening on the inner side of the cylinder;

in the present invention, the arc length is represented by L1, and L1 is represented by the length of the arc only.

In the present invention, the arc length L1 is divided equally and is not limited by the number of equal divisions: the more the number of divisions, the higher the drawing accuracy of the line, and the less the number of divisions, the lower the drawing accuracy of the line.

In a preferred embodiment, the arc length L1 is quartered, as shown in fig. 7, the arc length L1 is divided into four small arcs of equal length by three quartering points, and in the present invention, for clarity, the first quartering point is designated as a1, the second quartering point is designated as a2, and the third quartering point is designated as a 3.

C) And (4) projecting the opening 13, and determining the half chord length from the projection point of the bisector to the projection opening 9.

In a preferred embodiment, projected as shown in fig. 8, the half chord length from the projection point of the quartering point to the projection opening 9 is determined, and the half chord length has three; for clarity, the half chord length from the projection point of the first bisector a1 to the projection aperture 9 is denoted by d1, the half chord length from the projection point of the second bisector a2 to the projection aperture 9 is denoted by d2, and the half chord length from the projection point of the third bisector a3 to the projection aperture 9 is denoted by d 3.

D) According to the data, drawing a line segment in a new plane by taking the half arc length, the arc length and the half chord length as parameters, wherein the half arc length is flush with the upper end of the arc length, and the lower endpoint of the half arc length is the axial central point of the opening; drawing the half-chord length at the corresponding equal division point perpendicular to the arc length or the half-arc length, connecting end point curves of the arc length and the half-chord length, and performing mirror image replication by taking the arc length as an axis to prepare an open-hole lofting line 1;

in a preferred embodiment, the line segment is drawn in a new plane by taking the half arc length L2, the arc length L1, the half chord length d1, the half chord length d2 and the half chord length d3 as parameters, as shown in FIG. 9, wherein the half arc length L2 is flush with the upper end of the arc length L1, and the lower end point of the half arc length L2 is the axial center point of the opening; the axial center point of the opening can be the center point 11 of the opening on the outer side of the cylinder body or the center point 12 of the opening on the inner side of the cylinder body; and the half chord length d1, the half chord length d2 and the half chord length d3 are respectively drawn perpendicular to the arc length L1 or the half arc length L2 at the projection positions of the corresponding quartering points, the end point curves of the line sections are connected, and are subjected to mirror image replication by taking the arc length L1 as an axis to prepare the open pore lofting line 1.

As shown in fig. 13, the inner bevel line 5 is a lofting view of the inner side of the cylinder;

in the invention, according to the drawing method of the opening lofting line 1, the inner edge line 3, the groove outer edge line 4 and the inner groove line 5 can be drawn.

In a preferred embodiment, the distance from the upper end point of the groove outer edge line 4 to the connecting pipe is equal to the distance from the lower end point of the groove outer edge line 4 to the connecting pipe, and the distance is the groove width D.

According to the method, the problem that the width of the non-centripetal connecting pipe and the local groove of the cylinder body is too large can be solved by determining the width D of the groove, so that the filling amount of welding deposited metal at the periphery of the groove is basically consistent, the welding amount is reduced, the welding deformation can be effectively controlled, and the post-welding size of the connecting pipe is ensured.

In a preferred embodiment, the initial plotting of the hole loft line 2 comprises the following steps:

a) determining an angle formed between a connecting line from the center of the cylinder 20 to the outer upper end point of the cylinder 20 and a connecting line from the center of the cylinder 20 to the inner lower end point of the cylinder 20, or determining an angle formed between a connecting line from the center of the cylinder 20 to the outer lower end point of the cylinder 20 and a connecting line from the center of the cylinder 20 to the inner upper end point of the cylinder 20 when the center of the cylinder is above the opening 13;

in one embodiment, the center of the section of the cylinder is connected with the upper end point on the outer side of the cylinder, and the center of the section of the cylinder is connected with the lower end point on the inner side of the cylinder, and a certain angle is formed between the two connecting lines, wherein the angle is represented by i for convenience of description;

b) performing rotary excision within the angle range to obtain an centripetal hole;

in a preferred embodiment, the centripetal rotary cutting of the cylinder 20 within said angular range results in a centripetal hole; in a more preferred embodiment, as shown in FIG. 10, the cylinder 20 is cut centripetally in a rotary manner with the i/2 angle line as the axis and the i/2 angle as the range, resulting in a centripetally oriented hole.

c) Processing the centripetal hole to obtain an initial centripetal hole lofting line 2;

in a preferred embodiment, the centripetal aperture is projected radially, i.e. projected towards the centripetal aperture along an i/2 angular line, resulting in an initial centripetal aperture loft line 2, wherein the cylinder outside opening centre point 11 is below said initial centripetal aperture loft line 2.

In the invention, the initial centripetal hole lofting line 2 is superposed with the central point of the groove inner edge line 3, and the overlapped and crossed part of the two is a walnut-shaped area 6;

in a preferred embodiment, the center point 11 of the opening hole on the outer side of the cylinder body of the initial centripetal hole lofting line 2 and the groove inner edge line 3 is coincident, as shown in fig. 11, it is found that the initial centripetal hole lofting line 2 has an area beyond the inner edge line 3 of the groove, and the range of centripetal gas cutting cannot be larger than the range of the opening hole 13, so that the intersection of the two is taken to obtain a walnut-shaped area 6 as the overlapped intersection part of the two, and the remaining part in the groove inner edge line 3 is a shadow area 7.

And the center points of the groove inner edge line 3, the groove outer edge line 4 and the walnut-shaped area 6 are superposed and combined to obtain a cylinder body outer side lofting drawing;

in a preferred embodiment, as shown in fig. 12, the groove inner edge line 3, the groove outer edge line 4 and the center point 11 of the opening on the outer side of the cylinder of the walnut-shaped area 6 are drawn to coincide and merge, so as to obtain a lofting map on the outer side of the cylinder, wherein the non-overlapped part of the groove inner edge line 3 and the groove outer edge line 4 is an oblique line area 8;

in the invention, a cylinder body outer side lofting drawing or a cylinder body inner side lofting drawing is more preferably printed on the auxiliary tool;

in a preferred embodiment, the auxiliary tool is printed with a lofting drawing of the outer side of the cylinder, and when in use, the groove outer edge line 4 is cut first, and the groove outer edge line 4 is scribed on the outer side of the cylinder 20 by the auxiliary tool; cutting out the inner edge line 3 of the groove from the auxiliary tool, and scribing the inner edge line 3 of the groove on the outer side of the cylinder body 20 by using the auxiliary tool; finally, cutting out the contour line of the walnut-shaped area 6 by the aid of the aid, and cutting out the contour line of the walnut-shaped area 6 on the outer side of the barrel body 20 by the aid of the aid; the scribing sequence comprises a groove, an opening and a centripetal hole.

In a preferred embodiment, a hole center point is found on the cylinder 20 to be welded, the cylinder outer side hole center point 11 and the cylinder inner side hole center point 12 of the auxiliary tool are respectively superposed with the corresponding hole center points, and then lines in the auxiliary tool are scribed on the cylinder through cutting and scribing;

the auxiliary tool provided by the invention is used for assisting in drawing the perforating lofting line 1 at the position to be perforated of the cylinder body 20 and assisting in perforating operation of the welding groove, and is simple to manufacture, convenient to operate and strong in flexibility; and additional machining is not needed, the groove machining effect is effectively improved, the auxiliary tool is reused after being cut for many times, the operation is simple and convenient, and materials are saved.

Step 2') gas cutting to remove the walnut-shaped area 6;

in a preferred embodiment, the portion of the barrel corresponding to the walnut-shaped zone 6 is removed by a centripetal cutting outside the barrel 20;

when the cylinder 20 is directly subjected to gas cutting and hole opening, the root of the groove is easily accidentally injured in the gas cutting process, so that the local groove is larger, and the gap between the root of the groove is uneven when the pipe is subsequently welded. The invention firstly performs gas cutting on the centripetal hole, and aims to avoid directly opening the hole to hurt the root of the groove.

For products with large connecting pipe diameter and large holes, the manual gas cutting difficulty is relatively small, and the step of gas cutting to the radial holes can be omitted; for products with small connecting pipe diameter and small holes, the manual gas cutting difficulty is relatively high, and the final hole forming quality can be ensured only by gas cutting towards the center hole.

After the walnut-shaped region 6 is removed outside the cylinder 20 by a heart-wise cutting as shown in fig. 14, a part of the region outside the cylinder 20 has reached the opening size requirement, wherein the region outside the cylinder 20 that does not reach the opening size requirement is shown as a shaded region 7 in fig. 14.

Step 3') removing the shadow area 7;

in a preferred embodiment, the shaded area 7 is removed outside the cylinder 20 parallel to the direction of the aperture axis; at this point, the outside of the cartridge 20 has reached the opening size requirement. There is a portion of the area inside the barrel 20 that does not meet the opening size requirement.

Step 4') cutting off the inner part of the opening by gas cutting;

in a preferred embodiment, the inside of the hole is cut off by gas cutting from the inside of the cylinder 20 along the inside bevel line 5 in parallel to the direction of the hole axis; at this time, the cylindrical body 20 completes the boring operation.

Step 5') gas cutting to remove the oblique line area 8;

in a preferred embodiment, the oblique line region 8 is gas-cut along the bevel outer edge line 4 on the outer side of the cylindrical body in the direction of connecting the bevel outer edge line 4 and the bevel inner line 5, and the gas-cutting direction is changed in the circumferential direction of the connecting line as indicated by arrows in fig. 14. At this time, the cylindrical body 20 is completely perforated.

In the invention, the groove is machined by adopting a gas cutting centripetal hole, trepanning and groove three-step gas cutting method, so that the accuracy of the gas cutting groove can be effectively ensured, the gas cutting trepanning is ensured not to damage the root part of the groove, the defect of manual gas cutting rough machining is overcome to a certain extent, and the machined groove meets the high requirement of pattern design.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", and the like indicate orientations or positional relationships based on an operating state of the present invention, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected" and "connected" are to be construed broadly, and may be, for example, a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; the connection may be direct or indirect via an intermediate medium, and may be a communication between the two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features related to the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The present invention has been described above in connection with preferred embodiments, but these embodiments are merely exemplary and merely illustrative. On the basis of the above, the invention can be subjected to various substitutions and modifications, and the substitutions and the modifications are all within the protection scope of the invention.

Claims (13)

1. Pressure vessel with a non-centripetal nozzle (10), characterized in that the non-centripetal nozzle (10) is non-centripetally connected to the vessel's barrel (20);

a welding groove is formed in the cylinder body (20), and the non-centripetal connecting pipe (10) is welded with the cylinder body (20) through the groove;

the groove is a single-side V-shaped groove;

the distance from the upper end point of the outer side of the groove of the cylinder body to the connecting pipe (10) is equal to the distance from the lower end point of the outer side of the groove of the cylinder body to the connecting pipe (10);

the groove is formed by cutting along a lofting line step by step, and the lofting line on the auxiliary tool comprises a hole-opening lofting line (1) and an initial centripetal hole lofting line (2).

2. Pressure vessel according to claim 1, wherein the non-centripetal nozzle (10) is welded to the cylinder (20).

3. The pressure vessel of claim 1, wherein the cutting is performed according to the following steps:

1') finding a hole center point on a cylinder (20) to be welded, respectively coinciding a hole center point (11) on the outer side of the cylinder and a hole center point (12) on the inner side of the cylinder of an auxiliary tool with the corresponding hole center points, and scribing lines in the auxiliary tool on the cylinder by cutting and scribing;

the hole-opening lofting line (1) comprises a groove inner edge line (3), a groove outer edge line (4) and an inner side groove line (5), wherein the inner side groove line (5) is a cylinder inner side lofting drawing;

the initial centripetal hole lofting line (2) is superposed with the central point of the groove inner edge line (3), and the overlapped and crossed part of the two lines is a walnut-shaped area (6);

the shadow area (7) is formed in the remaining part of the inner edge line (3) of the groove except the walnut-shaped area (6);

the non-overlapped part of the inner edge line (3) of the bevel and the outer edge line (4) of the bevel forms a slash area (8);

2') cutting off the walnut-shaped region (6);

3') removing the shadow zone (7);

4') cutting off the inner part of the opening;

5') cutting out the oblique line area (8).

4. The pressure vessel of claim 3, wherein the bevel is cut by gas cutting,

in step 2'), the walnut-shaped area (6) is removed by heart-gas cutting outside the cylinder;

in the step 3'), a shadow area (7) is removed on the outer side of the cylinder body in a direction parallel to the opening axis;

in the step 4'), the inner part of the opening is cut off by gas cutting along the direction of the inner slope line (5) parallel to the axis of the opening from the inner side of the cylinder;

and 5') gas cutting the outer side of the cylinder along the outer edge line (4) of the groove to remove the oblique line region (8), wherein the gas cutting direction is a connecting line between the outer edge line (4) of the groove and the inner edge line (5), and the gas cutting direction is continuously changed along the circumferential direction of the connecting line.

5. The pressure vessel of claim 4,

the auxiliary tool in the step 1') is used for drawing a lofting line.

6. The pressure vessel of claim 5, wherein the auxiliary tool draws, prints or stamps the loft line, the auxiliary tool to weld opening ratio being 1: 1.

7. The pressure vessel of claim 6, wherein the auxiliary tool is bendable.

8. The pressure vessel of claim 4,

and the central points of the inner edge line (3) of the groove, the outer edge line (4) of the groove and the walnut-shaped area (6) are superposed and combined, and the obtained combination is the lofting drawing of the outer side of the cylinder body.

9. The pressure vessel of claim 8,

the distance from the upper end point of the groove outer edge line (4) to the upper end of the outer wall of the connecting pipe is equal to the distance from the lower end point of the groove outer edge line (4) to the lower end of the outer wall of the connecting pipe, and the set value of the distance can be changed according to welding requirements.

10. Pressure vessel according to claim 8, characterized in that the aperture loft line (1) is drawn according to the following steps:

A) drawing a cylinder body (20), and drawing an opening (13) on the cylinder body (20), wherein the axis of the opening is the axis of a connecting pipe; determining the intersection point of the opening axis and the cylinder (20) as an axial center point of the opening, and then determining the half arc length between the top point of the opening on the same side of the cylinder (20) and the center point of the opening;

B) determining the arc length between the upper end point and the lower end point of the opening on the same side of the cylinder (20), and equally dividing the arc length;

C) projecting the opening (13), and determining the half chord length from the projection point of the bisector to the projection opening (9);

D) drawing a line segment in a new plane by taking the half arc length, the arc length and the half chord length as parameters according to the obtained data, wherein the half arc length is flush with the upper end of the arc length, and the lower endpoint of the half arc length is an axial central point of the opening; and drawing the half chord length at the corresponding equal points in a manner of being vertical to the arc length or the half arc length, connecting end point curves of the arc length and the half chord length, and performing mirror image replication by taking the arc length as an axis to prepare the open pore lofting line (1).

11. The pressure vessel of claim 10,

in the step B), the arc length is divided into four equal parts;

and in the step C), the opening (13) is projected along the axis direction of the connecting pipe, and the half chord length from the projection point of the quartering point to the projection opening (9) is determined, wherein the half chord length is three.

12. Pressure vessel according to claim 10, characterized in that the initial centripetal lofting line (2) is plotted according to the following steps:

a) determining an angle formed between a connecting line from the center of the cylinder (20) to the outer upper end point of the cylinder (20) and a connecting line from the center of the cylinder (20) to the inner lower end point of the cylinder (20) in the step A), or determining an angle formed between a connecting line from the center of the cylinder (20) to the outer lower end point of the cylinder (20) and a connecting line from the center of the cylinder (20) to the inner upper end point of the cylinder (20) when the center of the cylinder is above the opening (13);

b) performing rotary excision within the angle range to obtain an centripetal hole;

c) and processing the centripetal hole, and projecting the centripetal hole to obtain an initial centripetal hole lofting line (2).

13. The pressure vessel of claim 12, wherein the centripetal aperture is radially projected.

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