Method for manufacturing weak-rigidity large-diameter conical section of rotary kiln

Abstract

A manufacturing method for a weak-rigidity large-diameter conical section of a rotary kiln relates to the technical field of rotary kiln manufacturing, and comprises the following steps: 1, expanding a conical part into a fan-shaped surface, and uniformly dividing the fan-shaped surface into a plurality of reference fan-shaped surfaces; 2, dividing the plurality of reference sectors into a plurality of rolling groups; 3, a plurality of reference material blanks are obtained through blanking based on the reference sectors; 4, sequentially welding and connecting the reference material blanks in the same rolling group to obtain a plurality of rolling material blanks; 5, marking the position of each round hole to be processed on the rolled material blank; 6, the multiple rolled material blanks are rolled to be round and welded into a complete conical part, and the upper shell ring and the lower shell ring are welded; 7, rechecking the position mark of the round hole to be machined, and cutting a blank hole in the conical part according to the mark after annealing treatment; and 8, finish-milling the blank hole by using a milling machine to finish the machining of a round hole, thereby completing the overall machining. By optimizing the machining process of the weak-rigidity large-diameter conical section, on the premise that the machining quality is guaranteed, the manufacturing time is shortened, and the requirement for the production schedule is met.

Description

Technical Field

[0001] This invention relates to the field of rotary kiln manufacturing technology, specifically a method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln. Background Technology

[0002] The currently operating φ7.2×138.5 meter coal chemical kiln uses low-rank coal as raw material and achieves mild pyrolysis under normal pressure, low temperature, and fully sealed conditions to obtain upgraded coal, low-temperature coal tar, and coal gas rich in methane and hydrogen. The kiln shell has a diameter of φ7.2 meters and a total length of 138.5 meters. The conical section is made of 80 mm thick pearlitic heat-resistant steel plate, and 210 φ328 mm circular holes are arranged on the cone. The axis of the circular holes is not perpendicular to the plate surface, but parallel to the axis of the cone, which makes the manufacturing process extremely difficult.

[0003] If the round hole is cut before the flat plate is rolled, the rigidity of the part will be reduced. Both rolling and welding will cause significant deformation of the product, and the size of the round hole will also deviate after rolling. If the round hole is cut after the tapered section is formed, the quality of the hand-cut surface will be poor, and the accumulation of internal stress during cutting will easily cause cracks in the cut surface, with unimaginable consequences. Moreover, if post-weld processing is used, the processing cycle is expected to be 2 months, and multiple stress relief treatments are required during processing to control processing accuracy, which will make it impossible to meet the production schedule. Summary of the Invention

[0004] The purpose of this invention is to provide a method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln. By optimizing the steps of blanking, welding, marking irregular holes, rolling, overall welding, and step-by-step hole processing, the manufacturing time can be shortened while ensuring processing quality and meeting production schedule requirements.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln includes the following steps: S1. Based on the dimensions of the conical part in the conical segment, determine the fan-shaped surface of its planar unfolding, and divide the fan-shaped surface into multiple reference fans on an equal basis; S2. Divide multiple reference sectors into multiple roll groups, each roll group including one or more reference sectors connected in sequence; S3. Based on the dimensional parameters of the reference sector, cut materials separately to obtain multiple reference blanks; S4. Weld the reference blanks in the same rolling group together in sequence to obtain multiple rolled blanks; S5. Mark the position of each hole to be processed on the rolled blank; S6. Using a plate rolling machine, roll multiple rolled blanks to a predetermined arc, and weld the multiple rolled blanks into a complete conical part, and weld the upper and lower cylinder sections at both ends of the conical part; S7. Re-inspect the position markings of the round holes to be processed, and cut out the blank holes on the tapered part according to the markings after annealing. S8. Use a milling machine to finish mill the blank hole to complete the round hole machining, and the overall machining is completed.

[0007] Furthermore, in S1, when dividing the reference sector, the dividing line must avoid the position of the circular hole to be processed, and the position distribution of the circular hole to be processed on each reference sector must be the same.

[0008] Furthermore, in S3, when cutting material based on the dimensions of the reference sector, a pressure head needs to be reserved on the outer edge of the reference blank located at both ends of the rolling group. The pressure head is cut off after the rolling blank is rolled into a circle.

[0009] Furthermore, in S4, the reference blanks in the same rolling group are welded together sequentially, including the following steps: S41. After smoothing the corresponding edges of adjacent reference blanks, connect them together; S42. Weld connecting plates at both ends of the butt joint. The connecting plate on the outer side is cut with an arc according to the outer arc diameter, and the connecting plate on the inner side is cut with an arc according to the inner arc diameter. The upper surface of the connecting plate is flush with the root of the bevel on the front side. S43. Weld the arc-starting plate onto the flat surface of the connecting plate. During welding, the upper surface of the arc-starting plate shall be flush with the inner side of the bevel. S44. Use a heater to heat the part to be welded, and start welding when it reaches the preset temperature, and maintain the temperature during the welding process.

[0010] Further, in S5, marking the positions of each circular hole to be processed on the rolled blank includes the following steps: S51. Draw the outline of each circular hole to be processed on the rolled blank. The outline dimensions are calculated based on the neutral layer. S52. Draw the cross center lines of each contour line. Drill positioning holes at the four intersections of the contour lines and the corresponding cross center lines. Mark the positions of the four arc-starting holes on each contour line. The four arc-starting holes are symmetrical about the cross center lines. The diameter of the arc-starting holes is 20 mm. The distance between the center of the arc-starting hole and the contour line is 5 mm. The distance between two corresponding arc-starting holes at the top and bottom is less than the distance between two corresponding arc-starting holes at the horizontal level. Drill all the arc-starting holes.

[0011] Furthermore, in step S6, during the rolling process, the side with the outline drawn is located on the side of the concave arc.

[0012] Furthermore, in step S6, after multiple rolled blanks are welded into a complete conical part, a straightening process is required.

[0013] Furthermore, in step S7, the positions of all contour lines, cross center lines, positioning holes, and arc-starting holes on the inner side of the conical part are re-inspected, and six sample punches are evenly set along the re-inspected contour lines between two adjacent positioning holes.

[0014] Furthermore, in step S7, cutting the blank hole includes the following steps: S71. After the conical section is annealed, it is cut while still warm. From the inside of the conical part, using the arc-starting hole, gas cutting is used to cut along the contour line and the punch between the two upper arc-starting holes and the two lower arc-starting holes in each contour line, leaving the part between the two corresponding upper and lower arc-starting holes uncut. S72, Second annealing treatment; S73. Cut the portion between the two corresponding arc-starting holes on each contour line to complete the blank hole machining.

[0015] Furthermore, in step S8, the milling machine performs finishing on each blank hole along the axis of the conical segment to obtain a circular hole with an axis parallel to the axis of the conical segment.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: 1. This invention reduces the difficulty of operation and ensures the accuracy of the hole position by marking the position of the circular hole to be processed and processing the arc-starting hole before rolling the blank into a circle, and verifying the position after rolling into a circle, and then processing the blank hole. 2. The present invention cuts the blank hole in two steps. After the first heat treatment, most of the blank hole outline is cut out. Then, after the second heat treatment, the remaining outline is cut out, so that the internal stress of the cone segment is released more fully and the overall structure is more stable. 3. This invention obtains a round hole by first manually cutting the blank hole with gas and then using a machine tool to precision machine the blank hole, resulting in higher processing quality; 4. By preheating before welding and setting an arc-starting plate, this invention can effectively avoid quality problems such as cracking and root defects during thick plate welding; 5. This invention adopts segmented processing and makes full use of the heat treatment interval time, thereby improving processing efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the cone segment in the embodiment.

[0018] Figure 2 This is a schematic diagram illustrating the division of the sector and the reference sector in the embodiment.

[0019] Figure 3 This is a schematic diagram of the structure of the rolled blank corresponding to the first rolling group in the embodiment.

[0020] Figure 4This is a schematic diagram of the structure of the rolled blank corresponding to the second rolling group in the embodiment.

[0021] Figure 5 This is a schematic diagram of the overall structure of the template.

[0022] Figure 6 This is an enlarged schematic diagram of point A on the template.

[0023] Figure descriptions: 1. Conical section, 11. Upper cylinder section, 12. Lower cylinder section, 2. Fan-shaped surface, 21. Reference fan, 3. Reference blank, 31. Press head, 4. Rolled blank, 5. Hole to be processed, 51. Outline, 52. Cross center line, 53. Positioning hole, 54. Arc-starting hole, 6. Template. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the features and performance of a method for manufacturing a weakly rigid large-diameter cone section of a rotary kiln according to the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Please see the appendix Figures 1-6 A method for manufacturing a large-diameter, weakly rigid cone section of a rotary kiln includes the following steps.

[0026] S1. Based on the dimensions of the conical portion 1 in the conical segment, determine its unfolded sector surface 2, and divide the sector surface 2 into multiple reference sectors 21 on an equal basis. When dividing the reference sectors 21, the dividing lines should avoid the positions of the circular holes 5 to be processed, and the positions of the circular holes 5 to be processed on each reference sector 21 should be distributed in the same way.

[0027] Specifically, the number of reference sectors 21 divided by the sector 2 is determined according to the actual size of the specific processing target and the distribution of the circular holes. This embodiment uses a conical part 1 with a large diameter of 7.2 meters and a small diameter of 2.8 meters, and 210 φ328 mm circular holes evenly distributed in 5 concentric rings from top to bottom as an example. Its sector 2 is as follows... Figure 2 As shown, the sector 2 is evenly divided into seven reference sectors 21, which ensures that the dividing line avoids the position of the circular hole, and the position distribution of the circular hole 5 to be processed in each reference sector 21 is the same.

[0028] S2. Divide the multiple reference sectors 21 into multiple roll groups, each roll group including one or more reference sectors 21 connected in sequence.

[0029] S3. Based on the dimensional parameters of the reference sector 21, cut the blanks separately to obtain multiple reference blanks 3. When cutting the blanks based on the dimensions of the reference sector 21, a pressure head 31 needs to be reserved on the outer edge of the reference blanks 3 located at both ends of the rolling group, so that both ends of the welded rolled blank 4 have pressure heads 31, which facilitates the subsequent rolling process. The pressure heads 31 are removed after the rolled blank 4 is rolled into a circle.

[0030] Specifically, if the rolling group contains only one reference sector 21, then pressure heads 31 need to be reserved on both sides of the corresponding reference blank 3 to facilitate the rolling machine's rolling. If the rolling group contains two or more reference sectors 21, pressure heads 31 only need to be reserved on the outer sides of the reference sectors 21 located at both ends. In this embodiment, since there are a total of seven reference sectors 21, it is divided into two rolling groups. Rolling group one contains three reference sectors 21, and rolling group two contains four reference sectors 21. Both rolling group one and rolling group two reserve pressure heads 31 on the outer sides of the reference sectors 21 located at both ends.

[0031] S4. The reference blanks 3 in the same rolling group are welded together in sequence to obtain multiple rolled blanks 4, including the following steps.

[0032] S41. After smoothing the corresponding edges of the adjacent reference blanks 3, connect them.

[0033] S42. Weld connecting plates at both ends of the butt joint. The connecting plate on the outer side is cut with an arc according to the outer arc diameter, and the connecting plate on the inner side is cut with an arc according to the inner arc diameter. The upper surface of the connecting plate is flush with the root of the bevel on the front side.

[0034] S43. Weld the arc-starting plate to the flat surface of the connecting plate. During welding, the upper surface of the arc-starting plate is flush with the inner side of the bevel.

[0035] S44. Use a heater to heat the part to be welded, and start welding when it reaches the preset temperature, and maintain the temperature during the welding process.

[0036] Since there are two rolling groups in this embodiment, two rolled blanks 4 are obtained by welding. One rolled blank 4 contains three reference blanks 3, and the other rolled blank 4 contains four reference blanks 3. Figure 3 and Figure 4 As shown.

[0037] S5. Mark the positions of each circular hole 5 to be processed on the rolled blank 4, including the following steps.

[0038] S51. Draw the outline 51 of each circular hole 5 to be processed on the rolled blank 4. The dimensions of the outline 51 are calculated according to the neutral layer.

[0039] S52. Draw the cross center line 52 of each contour line 51. Drill positioning holes 53 at the four intersection points of the contour line 51 and the corresponding cross center line 52. Mark the positions of four arc-starting holes 54 on each contour line 51. The four arc-starting holes 54 are symmetrical about the cross center line 52. The diameter of the arc-starting hole 54 is 20 mm. The distance between the center of the arc-starting hole 54 and the contour line 51 is 5 mm. The distance between two corresponding arc-starting holes 54 at the top and bottom is less than the distance between two corresponding arc-starting holes 54 at the horizontal level. Drill all the arc-starting holes 54.

[0040] Specifically, the marking hole 53 mainly serves a positioning function. In this embodiment, a blind hole with a diameter of 2 mm is used, which can be completed using a hand drill. The arc-starting hole 54 has two functions: first, it facilitates subsequent gas cutting; second, by setting the distance between two corresponding upper and lower arc-starting holes 54 to be much smaller than the distance between two corresponding horizontal arc-starting holes 54, the outline 51 is divided into four arc segments (two long and two short), laying the foundation for subsequent steps. Since the size of the circular hole 5 to be processed in this embodiment is φ328 mm, the distance between two corresponding upper and lower arc-starting holes 54 is controlled between 30 and 50 mm.

[0041] Specifically, this step can be facilitated by additionally processing a 1:1 template 6. The size of the template 6 is determined based on the actual target size and ease of processing. In this embodiment, the template 6 is made according to half the size of the basic sector 21. The outline 51 of each circular hole 5 to be processed is drawn on the template 6 according to the drawing dimensions. The dimensions of the outline 51 are calculated based on the neutral layer. On each outline 51, a cross center line 52, a positioning hole 53, and an arc-starting hole 54 are drawn as required. The overall outline is cut along the outer arc of the outline 51 and the positioning hole 53. The arc-starting hole 54 is not processed. Figure 5 and Figure 6 As shown.

[0042] Draw the 1 / 2 dividing lines corresponding to each reference blank 3 on the rolled blank 4. By placing the template 6 on the corresponding area on the rolled blank 4, all the outline lines 51, cross center lines 52, positioning holes 53 and arc-starting holes 54 in that area can be easily drawn. Then, drill the positioning holes 53 and arc-starting holes 54 according to the drawn lines.

[0043] S6. Using a plate rolling machine, multiple rolled blanks 4 are rolled to a predetermined arc, and the rolled blanks 4 are welded together to form a complete conical part 1. Upper cylindrical sections 11 and lower cylindrical sections 12 are welded to both ends of the conical part 1. During rolling, the side with the outline 51 is located on the concave side of the arc. After rolling, each pressure head 31 is removed. Before splicing and welding two rolled blanks 4, the corresponding edges of adjacent rolled blanks 4 are smoothed and then joined together. During welding, connecting plates and arc-starting plates are also welded. After welding to form a complete conical part 1, straightening treatment is required.

[0044] S7. Re-inspect the position markings of the circular hole 5 to be processed, and re-inspect the positions of all contour lines 51, cross center lines 52, positioning holes 53, and arc-starting holes 54 on the inner side of the conical part 1. Then, evenly distribute six punches along the re-inspected contour lines 51 between two adjacent positioning holes 53. After annealing, cut the blank hole on the conical part 1 according to the markings, including the following steps.

[0045] S71. After annealing the conical section, cut it while it is still warm, ideally between 100 and 150°C. Starting from the inside of the conical section 1, use gas cutting with the help of the arc-starting holes 54 to cut along the contour lines 51 between the two upper arc-starting holes 54 and between the two lower arc-starting holes 54, leaving the portion between the corresponding upper and lower arc-starting holes 54 uncut. During cutting, a four-person symmetrical cutting method is used. If the temperature drops below 100°C during cutting, reheating is performed. After cutting, cover with asbestos for insulation to ensure slow cooling.

[0046] S72, undergo annealing again.

[0047] S73. Cut the portion between the two corresponding arc-starting holes 54 on each contour line 51 to complete the blank hole processing.

[0048] S8. Use a milling machine to finish mill the blank holes. The milling machine performs finish machining on each blank hole along the axis of the tapered section to obtain a round hole with the axis parallel to the axis of the tapered section. The round hole machining is completed, and the overall machining is finished.

[0049] In specific implementation, this invention discloses a method for rolling and forming a large-diameter weakly rigid conical section, a special material thick plate welding process, a method for scribing densely holed fan-shaped plate, and a method for manufacturing densely holed sections on a large-diameter conical segment.

[0050] The conical section 1 has a large opening diameter of 7.2 meters and a small opening diameter of 2.8 meters. It contains 210 φ328 circular holes arranged in five concentric rings from top to bottom. Due to its relatively poor overall rigidity, it is called a large-diameter, weak-rigidity conical section. Its structural schematic diagram is shown below. Figure 1 As shown.

[0051] I. Design of a large-diameter, densely packed conical segment splicing and material arrangement method.

[0052] When the entire conical part 1 is unfolded, it becomes a fan-shaped surface 2. Based on the distribution pattern of the circular holes 5 to be machined on the conical part 1, grouping them into sets of 1 / 7 of the fan shape effectively avoids the hole positions. Figure 2 As shown. Due to the large size of the unfolded fan-shaped surface 2, and considering the width of the plate, it was finally determined that the fan-shaped surface 2 would be divided into 7 reference fan-shaped sections 21, which were cut separately, resulting in a total of 7 reference blanks 3.

[0053] During production, the reference blank 3 needs to be spliced ​​into two halves, 3 / 7 and 4 / 7, and then the rolled blank 4 is rolled separately and assembled into a complete circle, as shown below. Figure 3 and Figure 4 As shown. Since the steel plate is 80mm thick, there will be some straight ends after rolling. Therefore, a 300mm pressure head 31 is left at both ends of the rolled blank 4, which is cut off after rolling.

[0054] II. Develop a special material thick plate welding process.

[0055] The product is made of 12Cr2Mo1VR material, which is highly susceptible to cold cracking and has extremely poor weldability, requiring preheating to 200-250℃ before welding. To avoid root defects causing cracking of the entire weld, the following welding method is adopted for splicing.

[0056] a. The joints of each reference blank 3 need to be smoothed before joining.

[0057] b. Weld connecting plates at both ends of the butt joint. The inner connecting plate is cut with an arc according to the inner arc diameter of the fan-shaped plate, and the outer connecting plate is cut with an arc according to the outer arc diameter of the fan-shaped plate. The connecting plates are made of Q235B or Q345B low alloy high strength steel, with specifications of 20mm×150mm×300mm. The upper surface of the connecting plate is flush with the root of the bevel on the front side, and the welding is firm.

[0058] c. Weld an arc-extinguishing plate (10mm x 40mm x 80mm) onto the flat surface of the connecting plate. During assembly, ensure that the inner side of the bevel is flush and the angle is consistent with the bevel angle.

[0059] d. Use a long, straight heater to heat the part to be welded. To avoid uneven heating of the steel plate and resulting deformation or misalignment, the heater must be placed in the exact center of the weld.

[0060] e. The entire weld seam is heated to above 200 ℃ before welding. During the welding process, the lower heater continuously heats and maintains the temperature. After welding, heat treatment is performed, followed by heat preservation, slow cooling, grinding, and flaw detection.

[0061] f. Form two rolled blanks, 3 / 7 and 4 / 7.

[0062] 3. Design a scribing template for a fan-shaped plate with dense holes.

[0063] The template 6 is unfolded into a 1:1 scale based on half of the reference sector 21, that is, 1 / 14 of the sector surface 2. All dimensions on the template 6 are calculated based on the neutral layer. The manufacturing process of the template 6 is as follows.

[0064] a. After unfolding to 1 / 2 of the reference sector 21, draw the hole positions according to the drawing dimensions. The circular holes 5 to be machined on the conical part 1 are unfolded into irregular elliptical outlines 51 in the flat state, such as... Figure 5 and Figure 6 As shown.

[0065] b. Draw 4-φ2mm positioning holes 53 at the intersection of each contour line 51 and the corresponding cross center line 52, as follows: Figure 6 As shown. The positioning holes 53 serve two purposes: firstly, to facilitate positioning by quickly drawing the cross center lines of each hole on the rolled blank 4; and secondly, to allow for quick inspection of the hole dimensions after the part has been rolled and welded.

[0066] c. Draw 4-φ20mm arc-starting holes 54 on both sides of the horizontal center line of each hole. The center position of the arc-starting hole 54 is 5mm away from the outline 51, and the spacing between two corresponding arc-starting holes 54 is 30-50mm. Figure 6 As shown.

[0067] d. Template 6 is made of a thin steel plate with a thickness of δ=2mm. A 6KW laser cutting machine is used to cut the material, and the outlines 51 and the outer arcs of the positioning holes 53 are cut out, as shown below. Figure 6 The black line in the middle indicates that the arc hole 54 is not cut.

[0068] IV. Develop a method for fabricating dense holes on a large-diameter conical segment.

[0069] Considering the dense arrangement of the circular holes 5 to be machined on the conical part 1 and the high cutting stress, if the holes are cut while the flat plate is in operation, on the one hand, the stress may not be released during the tapering process, causing the base material to tear along the edge of the hole; on the other hand, the rigidity may be insufficient to guarantee the tapering roundness and the post-weld dimensions. Therefore, the positioning holes 53 and arc-starting holes 54 are drilled while the flat plate is in operation. After the rolled blank 4 is rolled into shape, welded into a complete circle, and welded to the upper cylinder section 11 and lower cylinder section 12 at both ends, two "bridge" sections are left and cut off. After secondary annealing, the two "bridge" sections are cut off. The specific operation is as follows.

[0070] a. Draw the 1 / 14 dividing line on the two rolled blanks 4 of 3 / 7 and 4 / 7 according to the dimensions on the drawing.

[0071] b. Place template 6 on the rolled blank 4 according to the lines. Mark the positions of the hole outline 51, cross center line 52, positioning hole 53, and arc-starting hole 54 on template 6 with a punch. Drill 4-φ2mm positioning holes with a hand drill. The depth is not required. Drill the arc-starting hole 54 with a scribe line and drill it with a drill press. The positioning hole 53 and arc-starting hole 54 on the outline 51 of each hole serve as the alignment reference for the outline 51 of each hole after the tapered part 1 is welded.

[0072] c. Roll the rolled blank 4 into a circle on a 160 plate rolling machine, with the scribed side rolled on the inside. After rolling, cut off the pressure head 31 according to the line, weld it into a whole circle and straighten it. Then assemble and weld it with the upper cylinder section 11 and the lower cylinder section 12 into one piece.

[0073] d. Using template 6, re-inspect the position lines of the cross center line 52, positioning hole 53 and arc-starting hole 54 on each reference blank 3 from one side of the inner surface of the cone section. After passing the inspection, use template 6 to draw the hole outline line 51 again, and punch a punch along the circumference. Punch 6 punches between two adjacent positioning holes 53, for a total of 24 points.

[0074] e. After the conical section is annealed, the blank hole is cut while it is still warm (about 100-150℃). Four people cut symmetrically at the same time. During the cutting, the two sets of short arcs on each contour line 51 are not cut. During the cutting, the temperature of the steel plate cutting area is measured with a temperature gun at any time. If the temperature drops, it is heated to above 100℃ before cutting. After cutting, asbestos is used to cover the plate for heat preservation and slow cooling.

[0075] f. Perform annealing again to eliminate cutting thermal stress. After the second annealing, cut off the two sets of short arcs on each contour line 51. At this time, most of the thermal stress has been eliminated and the machining amount is very small. Then proceed with machining. Place the tapered section upright and mill the hole circumference allowance from top to bottom according to the drawing dimensions to complete the machining.

[0076] It should be noted that the parts not described in detail in this solution are all prior art. The above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln, characterized in that: Includes the following steps, S1. Based on the dimensions of the conical part (1) in the conical segment, determine the fan-shaped surface (2) of its planar unfolding, and divide the fan-shaped surface (2) into multiple reference fan-shaped areas (21) on an equal basis. S2. Divide multiple reference sectors (21) into multiple roll groups, each roll group including one or more reference sectors (21) connected in sequence. S3. Based on the dimensional parameters of the reference sector (21), cut materials to obtain multiple reference blanks (3); S4. The reference blanks (3) in the same rolling group are welded together in sequence to obtain multiple rolled blanks (4). S5. Mark the positions of each hole (5) to be processed on the rolled blank (4); S6. Using a plate rolling machine, roll multiple rolled blanks (4) to a predetermined arc, and weld the multiple rolled blanks (4) into a complete conical part (1), and weld the upper cylinder section (11) and the lower cylinder section (12) at both ends of the conical part (1). S7. Re-inspect the position markings of the round hole (5) to be processed, and cut out the blank hole on the tapered part (1) according to the markings after annealing. S8. Use a milling machine to finish mill the blank hole to complete the round hole machining, and the overall machining is completed.

2. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In S1, when dividing the reference sector (21), the dividing line must avoid the position of the circular hole (5) to be processed, and the position distribution of the circular hole (5) to be processed on each reference sector (21) must be the same.

3. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In S3, when cutting the material based on the dimensions of the reference sector (21), the outer edge of the reference blank (3) located at both ends of the rolling group needs to reserve a pressure head (31), which is cut off after the rolling blank (4) is rolled into a circle.

4. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In S4, the reference blanks (3) in the same rolling group are welded together sequentially, including the following steps: S41. After smoothing the corresponding edges of the adjacent reference blanks (3), they are joined together. S42. Weld connecting plates at both ends of the butt joint. The connecting plate on the outer side is cut with an arc according to the outer arc diameter, and the connecting plate on the inner side is cut with an arc according to the inner arc diameter. The upper surface of the connecting plate is flush with the root of the bevel on the front side. S43. Weld the arc-starting plate onto the flat surface of the connecting plate. During welding, the upper surface of the arc-starting plate shall be flush with the inner side of the bevel. S44. Use a heater to heat the part to be welded, and start welding when it reaches the preset temperature, and maintain the temperature during the welding process.

5. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In S5, the positions of each circular hole (5) to be processed are marked on the rolled blank (4), including the following steps: S51. Draw the outline (51) of each circular hole (5) to be processed on the rolled blank (4). The dimensions of the outline (51) are calculated according to the neutral layer. S52. Draw the cross center line (52) of each contour line (51). Drill positioning holes (53) at the four intersection points of the contour line (51) and the corresponding cross center line (52). Mark the positions of the four arc-starting holes (54) on each contour line (51). The four arc-starting holes (54) are symmetrical about the cross center line (52). The diameter of the arc-starting hole (54) is 20 mm. The distance between the center of the arc-starting hole (54) and the contour line (51) is 5 mm. The distance between the two corresponding arc-starting holes (54) at the top and bottom is less than the distance between the two corresponding arc-starting holes (54) at the horizontal level. Drill all the arc-starting holes (54).

6. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In step S6, during the rolling process, the side with the outline (51) is located on the side of the concave arc.

7. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In step S6, after multiple rolled blanks (4) are welded into a complete conical part (1), they need to be straightened.

8. The method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 5, characterized in that: In step S7, the positions of all contour lines (51), cross center line (52), positioning hole (53), and arc-starting hole (54) on the inner side of the conical part (1) are re-inspected, and 6 sample punches are evenly set along the re-inspected contour line (51) between two adjacent positioning holes (53).

9. A method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 7, characterized in that: In step S7, cutting the blank hole includes the following steps: S71. After the conical section is annealed, it is cut while still warm. From the inside of the conical part (1), the two upper arc-starting holes (54) and the two lower arc-starting holes (54) in each contour line (51) are cut along the contour line (51) and the punch with gas cutting through the arc-starting hole (54). The part between the two corresponding upper and lower arc-starting holes (54) is left uncut. S72, Second annealing treatment; S73. Cut the part between the two corresponding arc holes (54) in each contour line (51) to complete the blank hole processing.

10. A method for manufacturing a large-diameter, weakly rigid conical section of a rotary kiln as described in claim 1, characterized in that: In step S8, the milling machine performs finishing on each blank hole along the axis of the conical segment to obtain a circular hole with the axis parallel to the axis of the conical segment.

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