Processing technology for large-diameter cylinders with different wall thicknesses

Abstract

The invention relates to a machining technology for large-diameter cylinders with different wall thicknesses. The machining technology comprises the steps that the cylinders are divided into at least two identical arc sections in the circumferential direction; acquiring plane plate materials corresponding to sections with different wall thicknesses, and reserving machining allowances at two ends; the plane plate materials corresponding to the at least two sections included in each arc section are welded, and one faces of the at least two plane plate materials are flush to form the arc section which is unfolded to be a plane; base plates are welded on the surface plate materials except the surface plate material with the largest thickness on the step surface of the arc section which is unfolded into the plane, one side face of each base plate is attached to the surface plate materials, and the thickness of the base plate welded on each surface plate material is the same as the thickness difference between the surface plate material and the surface plate material with the largest thickness; after the arc section which is unfolded into the plane is subjected to edge rolling forming, the base plate is removed, the machining allowance is cut off, and a formed arc section is obtained; and the at least two formed arc sections are welded to form a cylinder. The machining difficulty of large-diameter cylinders with different wall thicknesses can be reduced, and the forming precision is improved.

Description

Technical Field

[0001] The invention relates to the field of large-scale cylinder manufacturing technology, and in particular to a processing technology for large-diameter cylinders with different wall thicknesses. Background Art

[0002] The function of the cylinder is to provide the pressure-bearing space required for the process, and it is one of the most important pressure-bearing components of the pressure vessel. Cylindrical cylinders (i.e., cylinders) and spherical cylinders are the most commonly used cylinder structures in engineering. Large-diameter cylinders are widely used in various steel structures, such as shield machines, rotating racks, proton therapy devices, etc. They are widely used in industry and play an important role in the performance, safety and stability of equipment.

[0003] For large diameter cylinders with different wall thicknesses in the axial direction, the current processing method is to divide them into two or more cylinder segments along the axial direction according to the wall thickness, and then form them separately, and then weld them to the required height. The direction of the weld is perpendicular to the axial direction of the cylinder, so it is called a circumferential weld. Among them, due to the length limit of the sheet, it is necessary to divide each cylinder segment into two or more identical arc segments in the circumferential direction according to the diameter of the cylinder segment, and each arc segment is formed separately and then welded to form a complete cylinder segment.

[0004] When using the above method, it is necessary to strictly control the forming diameter of each cylinder segment, and when riveting and welding are performed between two cylinder segments before welding, it is necessary to ensure that the riveting and welding gap and the amount of misalignment between the cylinder segments meet the requirements, so as to avoid the gap being too large, resulting in the inability to perform subsequent welding or the size being out of tolerance after welding. Therefore, very high requirements are placed on the forming accuracy, riveting and welding accuracy, and welder skills of the cylinder segments, and the process is relatively difficult. Summary of the invention

[0005] Based on the above description, the present invention provides a processing technology for large-diameter cylinders with different wall thicknesses to solve the problem that the processing methods in the related art have very high requirements on the forming accuracy, riveting and welding accuracy, and welder skills of the cylinder sections, and the process is relatively difficult.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: The present application provides a large diameter cylinder processing technology with different wall thicknesses, and the technical solutions adopted are as follows: A process for processing large diameter cylinders with different wall thicknesses, comprising: The cylinder is divided into at least two identical arc segments along the circumferential direction, and according to the different wall thicknesses of the cylinder, the arc segment includes at least two segments with different wall thicknesses in the axial direction; Obtaining plane sheets corresponding to segments with different wall thicknesses, and reserving machining allowances at both ends of each plane sheet corresponding to both sides of the segment in the circumferential direction; Welding the planar plates corresponding to at least two segments included in each arc segment, with one side of at least two planar plates flush, to form an arc segment unfolded into a plane; On the stepped surface of the arc segment unfolded into a plane, a backing plate is welded on the plane sheet except the plane sheet with the largest thickness, and one side of the backing plate is attached to the plane sheet. The thickness of the backing plate welded on each plane sheet is the same as the difference between the thickness of the plane sheet and the plane sheet with the largest thickness; After the arc segment unfolded into a plane is rolled into a circle, the backing plate is removed and the machining allowance is cut off to obtain a formed arc segment; At least two arc segments are welded to form a cylinder.

[0007] Preferably, when obtaining the planar sheets corresponding to the segments with different wall thicknesses and reserving a set length of machining allowance at both ends of each planar sheet corresponding to the two sides on the circumferential direction of the segment, of the two planar sheets corresponding to the two adjacent segments in an arc segment, a chamfer is provided on one side of the planar sheet with smaller thickness for connecting with the planar sheet with larger thickness.

[0008] Preferably, when pads are welded on the planar sheets except the planar sheet with the largest thickness on the stepped surface of the arc segment unfolded into a plane, multiple pads are welded on each planar sheet, and the multiple pads are evenly distributed on the entire surface of the planar sheet.

[0009] Preferably, when welding the flat plates corresponding to at least two segments included in each arc segment, gas shielded welding or submerged arc welding is used for welding.

[0010] Preferably, the backing plate is welded to the flat sheet material by intermittent welding.

[0011] Preferably, when rolling the arc segment unfolded into a plane into an arc segment, the machining allowances at both ends of the arc segment unfolded into a plane are pre-bent, and then the rolling is performed.

[0012] Preferably, a lifting hole is prefabricated on the machining allowance.

[0013] Compared with the prior art, the technical solution of the present application has at least the following beneficial technical effects: 1. The present application divides a cylinder into at least two identical arc segments along the circumferential direction, and each arc segment is divided into at least two segments with different wall thicknesses according to different wall thicknesses. The plane sheet corresponding to each segment is cut out, and then the plane sheet corresponding to at least two segments included in each arc segment is welded according to the design to form an arc segment in an unfolded state. The arc segment in the unfolded state is rolled into a round shape to obtain a formed arc segment that meets the design requirements, and then at least two formed arc segments are welded to form a cylinder. Through this process, the annular weld between two cylinder sections with different wall thicknesses of the cylinder is welded in a plane sheet state, and the welding difficulty is low and the precision is high; and each arc segment is formed separately and then welded to each other to form a cylinder. During welding, each arc segment is convenient for calibration to ensure that the weld gap between the two arc segments meets the requirements, ensure the smooth progress of welding work, reduce the welding difficulty and improve the welding precision, thereby reducing the cylinder processing difficulty and improving the forming precision. Furthermore, by welding a backing plate on the plane sheet material other than the plane sheet material with the largest thickness, the backing plate will fill the thickness difference between the corresponding plane sheet material and the plane sheet material with the largest thickness, so as to roll the arc segment unfolded into a plane into a round shape, thereby reducing the difficulty of rolling and ensuring the forming accuracy. Therefore, the processing technology of the present application can reduce the processing difficulty of large-diameter cylinders with different wall thicknesses and improve the forming accuracy.

[0014] 2. For cylinders with smaller diameters, the processing technology of the present application does not need to segment the cylinder in the circumferential direction if the sheet length is sufficient. The sheets corresponding to the cylinder sections with different wall thicknesses can be directly welded in a flat state to form a cylinder that is unfolded into a plane, and then directly rolled into a cylinder after welding the pad, thereby further reducing the difficulty of forming and improving the forming accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a cylinder and arc segments in a process for processing a large-diameter cylinder with different wall thicknesses provided by an embodiment of the present invention, wherein the cylinder is divided into two arc segments for illustration; Figure 2 A schematic diagram of the groove of a flat sheet material in a large-diameter cylinder processing process with different wall thicknesses provided in an embodiment of the present invention; Figure 3 A schematic diagram of flat plate welding in a large diameter cylinder processing process with different wall thicknesses provided by an embodiment of the present invention; Figure 4 A schematic diagram of the distribution of pads on a flat sheet in a process for machining a large-diameter cylinder with different wall thicknesses provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0018] It will be appreciated that spatial relationship terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It will be appreciated that, in addition to the orientations shown in the figures, spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0019] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. The "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0020] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0021] Reference Figure 1-4 As shown, the embodiment of the present application provides a large diameter cylinder processing process with different wall thicknesses, including: The cylinder is divided into at least two identical arc segments along the circumferential direction. According to different wall thicknesses of the cylinder, the arc segment includes at least two segments with different wall thicknesses in the axial direction.

[0022] The plane sheets corresponding to the segments with different wall thicknesses are obtained, and machining allowances are reserved at both ends of each plane sheet corresponding to the two sides of the segment in the circumferential direction.

[0023] The plane plates corresponding to at least two segments included in each arc segment are welded, and one side of the at least two plane plates is flush, so as to form an arc segment unfolded into a plane.

[0024] On the stepped surface of the arc segment unfolded into a plane, a pad is welded on the plane sheet except the plane sheet with the largest thickness, and one side of the pad fits the plane sheet. The thickness of the pad welded on each plane sheet is the same as the difference in thickness between the plane sheet and the plane sheet with the largest thickness.

[0025] After the arc segment unfolded into a plane is rolled into a circle, the backing plate is removed and the machining allowance is cut off to obtain a formed arc segment.

[0026] At least two formed arc segments are welded to form a cylinder.

[0027] Specifically, when the cylinder is divided into at least two identical arc segments along the circumferential direction, the number of arc segments is set according to the design diameter of the cylinder. On the premise of ensuring that the sheet length can meet the requirements, the number of arc segments is reduced as much as possible to reduce subsequent welding work. Figure 1 As shown, in this embodiment, the cylinder is divided into two arc segments for illustration, and the central angle of each arc segment is 180°. According to the different wall thicknesses of the cylinder, the arc segment includes at least two segments with different wall thicknesses in the axial direction, and each different wall thickness of the cylinder corresponds to a segment.

[0028] When obtaining the plane sheets corresponding to the segments with different wall thicknesses, a processing allowance of a set length is reserved at both ends of each plane sheet corresponding to the two sides of the segment in the circumferential direction.

[0029] Specifically, when cutting flat sheet materials, according to the conventional expansion method of equal-wall thickness cylinders, the expansion is carried out according to the center layer. The calculation formula for the cutting length of flat sheet materials is as follows: For cylinders with the same outer diameter: L = (R-δ / 2) × π + (machining allowance) × 2.

[0030] For cylinders with the same inner diameter: L=(r+δ / 2)×π+(machining allowance)×2.

[0031] Wherein, L is the blanking length, in mm; R is the outer radius of the cylinder, in mm; r is the inner radius of the cylinder, in mm; δ is the wall thickness, in mm.

[0032] Depending on the material, carbon steel is cut by CNC flame cutting, and stainless steel is cut by CNC water jet or laser cutting. At the same time, lifting holes are prefabricated on the processing allowance to facilitate the lifting and transfer of flat sheet materials.

[0033] Furthermore, in the two plane sheets corresponding to the two adjacent segments in an arc segment, the plane sheet with a smaller thickness has a bevel on one side for connecting with the plane sheet with a larger thickness. Specifically, a semi-automatic flame cutting machine is used to weld a bevel on a long side of the plane sheet with a smaller thickness. The bevel form is generally an X-shaped bevel, and the bevel angle is adjusted according to the wall thickness. Under the premise of meeting the weld performance, the welding filling amount is minimized. Figure 2 As shown, an X-shaped groove is used as an illustration in this embodiment.

[0034] After the planar sheet material is cut, the planar sheet materials corresponding to at least two segments included in each arc segment are welded, and one side of at least two planar sheets is flush to form an arc segment unfolded into a plane. The following steps are included: Grind the groove and the surrounding area within a certain range (e.g. 30-50mm) and expose it to light to clean rust, oil and other impurities.

[0035] Reference Figure 3 As shown, firstly, the plane plates corresponding to at least two segments included in each arc segment are riveted and welded into a whole, ensuring that one side is flush. In the figure, each arc segment includes two segments for illustration.

[0036] Before welding, the corresponding welding process assessment should be completed according to the standard requirements.

[0037] Use gas shielded welding (such as CO2 gas shielded welding) or submerged arc welding for welding, and select welding materials, shielding gas and welding parameters (including current, voltage, gas flow, welding speed, etc.) according to the qualified welding process regulations.

[0038] After welding is completed, grind the weld to make it smooth and check the overall flatness, which is required to be less than the set value (e.g. 2mm).

[0039] Non-destructive testing (RT, UT, PT, MT, etc.) is performed on the tailored welds. The testing methods and acceptance requirements are implemented according to the project product quality requirements.

[0040] After welding to obtain an arc segment that is unfolded into a plane, a pad is welded on the planar sheet except the planar sheet with the largest thickness on the step surface of the arc segment that is unfolded into a plane, and one side of the pad fits the planar sheet. The thickness of the pad welded on each planar sheet is the same as the difference in thickness between the planar sheet and the planar sheet with the largest thickness.

[0041] Specifically, while cutting the flat sheet, a number of pads of different thicknesses are cut according to the required pads. Figure 4As shown, in this embodiment, multiple pads are welded on each flat sheet, and the multiple pads are evenly distributed on the entire surface of the flat sheet, and each arc segment is illustrated in the figure as including two segments. The width and length dimensions, specific distribution method and gaps between the pads are designed and adjusted according to actual conditions, so that each flat sheet is covered by multiple pads, and the thickness difference between each flat sheet and the thickest flat sheet is made up by the pads. In the subsequent rolling process of the arc segment unfolded into a plane, the pads are in contact with the roller of the plate rolling machine, so that the forces on both sides of the arc segment are balanced, thereby successfully completing the rolling process.

[0042] When welding the pad, lay the arc segment that has passed the inspection and has been unfolded into a plane flat on the workbench, with the step surface facing up, and level it until the flatness is less than the set value (for example, 2mm). According to the designed pad size and distribution method, draw the pad distribution positioning dimension line on the flat sheet. First, rivet and weld the cut pad to the flat sheet according to the positioning dimension line, and fill the thickness step difference between the flat sheet except the thickest flat sheet and the thickest flat sheet to ensure that the two sides of the arc segment unfolded into a plane are flush. Use intermittent welding to weld the pad to the flat sheet. There is no need to fully weld between the pad and the flat sheet, just ensure that the pad and the flat sheet are firmly fixed.

[0043] After the pad is welded, the arc segment unfolded into a plane is rolled into a circle, the pad is removed, and the machining allowance is cut off to obtain a formed arc segment.

[0044] Specifically, a CNC horizontal downward adjustment three-roller plate rolling machine is used for rolling and forming. When rolling, pay attention to controlling the feed amount of the upper roller within the set value (for example, 5mm) each time. First, the machining allowance at both ends of the arc segment that is unfolded into a plane is appropriately pre-bent, and then the middle arc segment is rolled. The overhead crane is used to assist in the rolling process. At the same time, non-related personnel should stay away from the plate rolling machine as much as possible during the rolling process.

[0045] During the rolling process, the inner diameter needs to be continuously checked. In this embodiment, a master mold is used for detection. The master mold is obtained by laser cutting according to the standard inner diameter of the cylinder. The degree of fit between the master mold and the inner wall of the arc segment is used to determine whether the inner diameter of the detection position meets the design requirements. During actual detection, at least three sections in the axial direction of the arc segment are detected, and multiple positions in each area in the circumferential direction are detected. The rolling process is completed only after each detection position meets the design requirements.

[0046] After the arc segment is rolled into shape, the machining allowance is cut off and the pad is removed. The weld is cleaned and polished to make it smooth. The removed pad can be leveled on the plate rolling machine, reused or used for other parts.

[0047] After at least two arc segments are formed, at least two formed arc segments are welded to form a cylinder. After welding, the weld is cleaned and polished to make it smooth. The welded cylinder also needs to be tested for its inner diameter. If it passes the test, a large-diameter cylinder with different wall thickness but the same inner diameter or outer diameter that meets the design requirements is obtained.

[0048] For cylinders with smaller diameters, if the sheet length is sufficient, there is no need to segment the cylinder in the circumferential direction. The sheets corresponding to the cylinder sections with different wall thicknesses can be directly welded in a flat state to form a cylinder that is unfolded into a plane, and then directly rolled into a cylinder after welding the pad, thereby further reducing the difficulty of forming and improving the forming accuracy.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for processing large diameter cylinders with different wall thicknesses, characterized in that: include: The cylinder is divided into at least two identical arc segments along the circumferential direction, and according to the different wall thicknesses of the cylinder, the arc segment includes at least two segments with different wall thicknesses in the axial direction; Obtaining plane sheets corresponding to segments with different wall thicknesses, and reserving machining allowances at both ends of each plane sheet corresponding to both sides of the segment in the circumferential direction; Welding the planar plates corresponding to at least two segments included in each arc segment, with one side of at least two planar plates flush, to form an arc segment unfolded into a plane; On the stepped surface of the arc segment unfolded into a plane, a backing plate is welded on the plane sheet except the plane sheet with the largest thickness, and one side of the backing plate is attached to the plane sheet. The thickness of the backing plate welded on each plane sheet is the same as the difference between the thickness of the plane sheet and the plane sheet with the largest thickness; After the arc segment unfolded into a plane is rolled into a circle, the backing plate is removed and the machining allowance is cut off to obtain a formed arc segment; At least two formed arc segments are welded to form a cylinder.

2. The process for processing large diameter cylinders with different wall thicknesses according to claim 1, characterized in that: When obtaining the planar sheets corresponding to the segments with different wall thicknesses and reserving a set length of machining allowance at both ends of each planar sheet corresponding to the two sides of the segment in the circumferential direction, one side of the planar sheet corresponding to the two adjacent segments in an arc segment is chamfered on the side of the planar sheet with smaller thickness for connecting with the planar sheet with larger thickness.

3. The process for processing large-diameter cylinders with different wall thicknesses according to claim 1, characterized in that: When welding the flat plates corresponding to at least two segments included in each arc segment, gas shielded welding or submerged arc welding is used for welding.

4. The process for processing large diameter cylinders with different wall thicknesses according to claim 1, characterized in that: When pads are welded on the planar sheets except the planar sheet with the largest thickness on the stepped surface of the arc segment unfolded into a plane, multiple pads are welded on each planar sheet and the multiple pads are evenly distributed on the entire surface of the planar sheet.

5. The process for processing large diameter cylinders with different wall thicknesses according to claim 1, characterized in that: The backing plate is welded on the plane plate by intermittent welding.

6. The process for processing large diameter cylinders with different wall thicknesses according to claim 1, characterized in that: When the arc segment unfolded into a plane is rolled into an arc segment, the machining allowances at both ends of the arc segment unfolded into a plane are pre-bent, and then the rolling is performed.

7. The process for processing large diameter cylinders with different wall thicknesses according to claim 1, characterized in that: A lifting hole is prefabricated on the machining allowance.

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