Method for improving manufacturing precision of welded double-layer tube plate
Through the precision processing of the welding bevels and pipe holes of the welded double-layer pipe plate through back-to-back stacking turning and positioning technology, the problems of low coaxiality and large deformation during the manufacturing process are solved, and high-precision welded double-layer pipe plate manufacturing is achieved, improving the stability and heat transfer efficiency of the heat pipe.
Patent Information
- Application Number
- CN202510002149.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2025-02-28
AI Technical Summary
When manufacturing welded double-layer pipe plates, there are problems such as low coaxiality of the inner and outer pipe plates, insufficient assembly accuracy of welding bevels, and large deformation during processing and welding, resulting in poor stability, reliability and heat transfer efficiency of the heat pipe.
The welding bevels of the inner and outer pipe plates are precision-processed through the back-to-back stacking turning process, and the coaxiality of the pipe holes is ensured by technical means such as positioning direct pins and guide conical pins before welding. Then, the welded back plate and tie rod components are used to increase the stiffness during welding and reduce deformation.
The manufacturing accuracy of welded double-layer pipe plates is improved, ensuring high coaxiality of heat pipe holes and high assembly accuracy of welded bevels of inner and outer pipe plates, thereby improving the heat pipe stability, reliability and heat transfer efficiency of welded double-layer pipe plates.
Smart Images
Figure CN119525948A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of heat exchanger manufacturing, and in particular to a method for improving the manufacturing accuracy of a welded double-layer tube sheet. Background Art
[0002] A heat exchanger is a device that transfers part of the heat of a hot fluid to a cold fluid. It is also called a heat exchanger. It is widely used in energy, chemical, power, pharmaceutical and many other industrial productions. There are many types of heat exchangers. One type of heat exchanger uses a double tube sheet structure, called a double tube sheet heat exchanger. Each end of the heat exchange tube is connected to two tube sheets. The one close to the shell is called the inner tube sheet 1, and the one close to the tube is called the outer tube sheet 2. The heat exchange tube and the two tube sheets are usually connected by expansion or welding, or a combination of expansion welding.
[0003] In actual use, the double tube sheet structure generally includes assembled double tube sheets and welded double tube sheets. Among them, the welded double tube sheet is to firmly connect two tube sheets together by welding. The advantages of this method are tight connection, no leakage, and high strength and corrosion resistance.
[0004] like Figure 1 As shown, the welded double-layer tube sheet includes an inner tube sheet 1 and an outer tube sheet 2. The inner tube sheet 1 is provided with a plurality of inner tube sheet tube holes 11 penetrating the upper and lower ends thereof, and the outer tube sheet 2 is provided with outer tube sheet tube holes 21 corresponding to the inner tube sheet tube holes 11. In actual use, the inner tube sheet 1 and the outer tube sheet 2 are generally circular structures. The inner tube sheet 1 and the outer tube sheet 2 are provided with an inner tube sheet welding groove 12 and an outer tube sheet welding groove 22 on opposite sides, respectively. Before welding, after the welded double-layer tube sheet is assembled, the inner tube sheet welding groove 12 of the inner tube sheet 1 and the outer tube sheet welding groove 22 of the outer tube sheet 2 correspond to each other up and down, and a precision weld 3 is formed between the inner tube sheet welding groove 12 and the outer tube sheet welding groove 22; the inner tube sheet tube holes 11 of the inner tube sheet 1 and the outer tube sheet tube holes 21 of the outer tube sheet 2 correspond to each other up and down to form heat pipe holes for installing heat exchange tubes.
[0005] In order to ensure the quality of welded double-layer tube sheets, the following requirements and problems are generally encountered during the actual manufacture of welded double-layer tube sheets: 1. The coaxiality of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 in the welded double-layer tube sheet structure is required to be high, so as to ensure the stability, reliability and heat transfer efficiency of the heat pipe.
[0006] 2. The welding groove assembly accuracy requirements of the inner tube sheet 1 and the outer tube sheet 2 are high, which can improve the coaxiality of the heat pipe holes of the double-layer tube sheet to a certain extent, thereby further ensuring the stability, reliability and heat transfer efficiency of the heat pipe.
[0007] 3. In the actual manufacture of welded double-layer tube sheets, there are problems such as the inner tube sheet 1 and the outer tube sheet 2 are easy to deform during processing and welding due to their large diameter and thin thickness, and the low precision of the tube holes after welding the double-layer tube sheet makes it difficult to thread the tube.
[0008] Therefore, in view of the high requirements for manufacturing welded double-layer tube sheets and the problems encountered in actual processing and manufacturing, it is necessary to provide a method for improving the manufacturing accuracy of welded double-layer tube sheets, which has small deformation during processing and welding, high coaxiality of heat pipe holes, and high assembly accuracy of inner and outer tube sheet welding grooves 22. Summary of the invention
[0009] The purpose of the present invention is to provide a method for improving the manufacturing accuracy of welded double-layer tube sheets, which does not deform during processing and welding, has high coaxiality of heat pipe holes, and has high assembly accuracy of inner and outer tube sheet welding grooves, in view of the shortcomings of the prior art.
[0010] The technical purpose of the present invention is achieved by the following technical solutions: A method for improving the manufacturing accuracy of a welded double-layer tube sheet comprises the following steps: Step 1, respectively rough turning, fine turning and drilling the inner tube sheet and the outer tube sheet in the double-layer tube sheet; Step 2, the inner tube sheet and the outer tube sheet are arranged back to back, and after the tube holes of the inner tube sheet and the outer tube sheet are aligned, they are fixed together by fasteners; Step 3: Place the fixed double-layer tube sheets on a lathe for alignment; Step 4: After the alignment is completed, turn the welding groove of one tube sheet, and use the outer circle to turn the welding groove of the other tube sheet to find the alignment reference; Step 5, turn over the double-layer tube sheet and align it with the outer circle and end face turned in step 4, and turn the welding groove of another tube sheet; Step 6, performing tube hole coaxiality detection on the inner tube sheet and the outer tube sheet in the double-layer tube sheet; Step 7: After the tube hole coaxiality test is qualified, the double-layer tube sheet is precisely welded; Step 8: Pipe through the pipe hole.
[0011] Preferably, in step 2, when the inner tube sheet and the outer tube sheet are arranged back to back, a gasket with the same height as the cavity is first placed in the cavity between the inner tube sheet and the outer tube sheet; then a guide cone pin is used to guide the tube holes of the inner tube sheet and the tube holes of the outer tube sheet to be concentrically assembled; and then a plurality of positioning straight pins are used to correct the coaxiality of the tube holes of the inner tube sheet and the tube holes of the outer tube sheet and fix the relative positions of the inner and outer tube sheets.
[0012] Preferably, in step 2, a plug gauge smaller than the tube hole is used to detect whether the coaxiality of the tube hole of the inner tube sheet and the tube hole of the outer tube sheet is qualified. If unqualified, the positions of the tube hole of the inner tube sheet and the tube hole of the outer tube sheet are readjusted until the tube hole coaxiality test is qualified; and then a plurality of stud bolts matched with the tube hole of the inner tube sheet and the tube hole of the outer tube sheet are used to uniformly tighten the inner tube sheet and the outer tube sheet.
[0013] Preferably, the diameter of the positioning straight pin is 0.02-0.05 mm smaller than the diameter of the tube hole.
[0014] Preferably, in step 6, a guide cone pin is first used to pass through the inner tube sheet tube hole and the outer tube sheet tube hole of the double-layer tube sheet and the tube hole of the welding back plate; then a positioning straight pin with a diameter smaller than the hole diameter of the inner tube sheet tube hole and the outer tube sheet tube hole is used to correct the coaxiality and locate the position of the inner tube sheet tube hole and the outer tube sheet tube hole; if it is unqualified, the position of the inner tube sheet tube hole and the outer tube sheet tube hole is readjusted until the tube hole coaxiality test is qualified.
[0015] Preferably, in step 7, when precision welds are performed between the inner tube sheet and the outer tube sheet of the double-layer tube sheet, a welding back plate is arranged on the side of the inner tube sheet away from the outer tube sheet; the inner tube sheet, the outer tube sheet and the welding back plate are detachably fixedly connected by a plurality of spaced downward push rod assemblies; the inner tube sheet and the welding back plate are detachably fixedly connected by a plurality of spaced upward pull rod assemblies.
[0016] Preferably, the tube holes of the welding back plate correspond to the tube holes of the inner tube plate and the outer tube plate, and the diameter of the tube holes of the welding back plate is slightly larger than the tube holes of the inner tube plate and the outer tube plate.
[0017] Preferably, the push-down rod assembly consists of a double-headed screw, two nuts and a plurality of washers.
[0018] Preferably, the pull-up rod assembly is composed of a single-head screw with a square head or a hexagonal head having an eccentric step, a positioning washer and a nut.
[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The inner tube sheet and the outer tube sheet of the present invention are turned back to back to obtain precise inner tube sheet welding grooves and outer tube sheet welding grooves, so as to achieve the coaxiality of the inner and outer tube sheet tube holes and the precise inner and outer tube sheet welding grooves. Therefore, the present invention has the advantages of high tube hole coaxiality and high assembly precision of the inner and outer tube sheet welding grooves.
[0020] 2. The present invention improves the manufacturing accuracy of the welded double-layer tube sheet by tightly connecting the inner tube sheet and the welding back plate, thereby increasing the rigidity during welding and reducing welding deformation. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a cross-sectional view of a welded double-layer tube sheet; Figure 2 It is a schematic structural diagram of the inner tube sheet and the outer tube sheet of the present invention when they are arranged back to back; Figure 3 It is a structural schematic diagram of the inner tube plate, the outer tube plate and the welded back plate of the present invention; Figure 4 yes Figure 3 Schematic diagram of the structure in which the inner tube sheet, the outer tube sheet and the welding back plate are fixed together; Figure 5 yes Figure 4 Structural schematic diagram of the middle and upper pull rod assembly; Reference numerals: 1—inner tube sheet; 11—tube hole of inner tube sheet; 12—welding groove of inner tube sheet; 13—welding back plate; 131—tube hole of welding back plate; 2—outer tube sheet; 21—tube hole of outer tube sheet; 22—welding groove of outer tube sheet; 3—precision weld; 4—cavity; 41—washer; 5—positioning direct pin; 6—stud bolt; 7—upper pull rod assembly; 71—single-head screw; 72—positioning sleeve; 73—nut. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.
[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0024] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0025] like Figure 1 — Figure 5 As shown, a method for improving the manufacturing accuracy of a welded double-layer tube sheet comprises the following steps: Step 1, rough turning, fine turning and drilling are performed on the inner tube sheet 1 and the outer tube sheet 2 in the double-layer tube sheet respectively; Step 2, the inner tube sheet 1 and the outer tube sheet 2 are arranged back to back, and after the tube holes of the inner tube sheet 1 and the outer tube sheet 2 are aligned, they are fixed together by fasteners; Step 3: Place the fixed double-layer tube sheets on a lathe for alignment; Step 4: After the alignment is completed, turn the precision welding groove of one tube sheet, and use the alignment reference when turning the welding groove of the other tube sheet on the outer circle; Step 5, turn over the double-layer tube sheet and align it with the outer circle and end face turned in step 4, and turn the precision welding groove of another tube sheet; Step 6, performing tube hole coaxiality detection on the inner tube sheet 1 and the outer tube sheet 2 in the double-layer tube sheet; Step 7: After the tube hole coaxiality test is qualified, the double-layer tube sheet is precisely welded; Step 8: Pipe through the hole.
[0026] Specifically, firstly, the inner tube sheet 1 and the outer tube sheet 2 in the double-layer tube sheet are rough-turned, fine-turned and drilled respectively; the inner tube sheet 1 and the outer tube sheet 2 having the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 are manufactured; the inner tube sheet tube hole 11 of the inner tube sheet 1 and the outer tube sheet tube hole 21 of the outer tube sheet 2 correspond to each other up and down to form a heat pipe hole for installing the heat exchange tube. In the specific implementation, in order to ensure that the relative position between the tube holes is accurate when the inner tube sheet 1 and the outer tube sheet 2 are drilled respectively, the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 are processed by the same machine tool with qualified positioning accuracy and repeated positioning accuracy. The technical measures are adopted to improve the accuracy of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21. In order to control the flatness of the inner tube sheet 1 and the outer tube sheet 2; control the cutting parameters and reduce the cutting force; drill from the side with less turning, and the cutting force offsets part of the stress of the tube sheet removal. This technical measure is adopted to improve the flatness of the inner tube sheet 1 and the outer tube sheet 2.
[0027] Furthermore, precise inner tube sheet welding grooves 12 and outer tube sheet welding grooves 22 are respectively processed on the inner tube sheet 1 and outer tube sheet 2 that have been rough-turned, fine-turned and drilled.
[0028] like Figure 2As shown, specifically, the inner tube sheet 1 and the outer tube sheet 2 are first arranged back to back, and after the end faces of the inner tube sheet 1 and the outer tube sheet 2 are aligned, they are fixed together by fasteners. In a specific implementation, the inner tube sheet 1 and the outer tube sheet 2 are arranged back to back so that the inner tube sheet 1 has a side with an inner tube sheet 1 welding groove and the outer tube sheet 2 has a side with an outer tube sheet welding groove 22. Then, when the inner tube sheet 1 and the outer tube sheet 2 are assembled back to back, a gasket 41 with the same height as the cavity 4 is first placed in the cavity 4 between the inner tube sheet 1 and the outer tube sheet 2. Then, a guide cone pin (not shown in the figure) is used to guide the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 to be assembled concentrically; and then a plurality of positioning straight pins 5 are used to correct the coaxiality of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 and fix the relative positions of the inner and outer tube sheets 2. Among them, when the guide cone pin completes the guidance, the guide cone pin is pulled out.
[0029] like Figure 2 As shown, the inner tube sheet 1 and the outer tube sheet 2 are arranged back to back, and the 17 inner tube sheet tube holes 11 of the inner tube sheet 1 and the 17 outer tube sheet tube holes 21 of the outer tube sheet 2 are arranged correspondingly; the five positioning straight pins 5 arranged at intervals are respectively inserted from the upper inner tube sheet tube holes 11 into the lower outer tube sheet tube holes 21; the fastener is a stud bolt 6; the inner tube sheet 1 and the outer tube sheet 2 are fixed to each other by four stud bolts 6 arranged at intervals, thereby fixing the relative position of the inner tube sheet 1 and the outer tube sheet 2. Among them, the diameter of the positioning straight pin 5 is 0.02-0.05mm smaller than the diameter of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21. The material of the washer 41 is made of the same material as the tube sheet. The stud bolt 6 includes a stud screw and two bolts, and the washer 41 is provided with a through hole that cooperates with the stud screw. The washer 41 is arranged in the cavity 4 and cooperates with the stud screw. The number of washers 41 is the same as the number of stud bolts 6. The inner tube sheet 1 is a thin plate, which is easy to deform. By providing a gasket 41 with the same height as the cavity 4, the inner tube sheet 1 can be supported to ensure that the inner tube sheet 1 is not deformed due to external forces during processing, thereby improving the manufacturing accuracy of the welded double-layer tube sheet.
[0030] When installing the positioning pin 5, it is also necessary to check the coaxiality of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21. Specifically, use a plug gauge slightly smaller than the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 to check whether the coaxiality of the inner tube sheet 1 and the outer tube sheet 2 is qualified; if it is unqualified, readjust the position of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 until the coaxiality is qualified; when the coaxiality test of the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 is qualified, use multiple stud bolts 6 that match the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 to evenly tighten the inner tube sheet 1 and the outer tube sheet 2. The degree of tightening is based on the deformation of the thinner inner tube sheet 1 not exceeding 0.5mm. Among them, when the coaxiality of the tube hole is tested before welding, if it does not pass the plug gauge, the hole is reamed to the upper diameter difference. The adoption of this technical measure ensures the accuracy of machining the inner tube sheet welding groove 12 and the outer tube sheet welding groove 22, thereby improving the manufacturing accuracy of the welded double-layer tube sheet.
[0031] Further, after the inner tube sheet 1 and the outer tube sheet 2 are assembled, the welding groove of one tube sheet is turned after alignment on the lathe, and the alignment reference is used when the welding groove of the other tube sheet is turned on the outer circle. In a specific implementation, after alignment on the lathe, the inner tube sheet welding groove 12 is turned, and the alignment reference is used when the outer tube sheet welding groove 22 is turned on the outer circle; or after alignment on the lathe, the outer tube sheet welding groove 22 is turned, and the alignment reference is used when the inner tube sheet welding groove 12 is turned on the outer circle.
[0032] Further, the double-layer tube sheet is turned over and the outer circle and end face turned in step 4 are aligned, and the welding groove of another tube sheet is turned; in the specific implementation, the inner tube sheet 1 of the double-layer tube sheet with the inner tube sheet welding groove 12 already turned is turned over to the other side, and the outer circle and end face turned in the previous step are aligned, and the end face runout is controlled within 0.02mm, and the outer tube sheet welding groove 22 is turned; or the outer tube sheet 2 of the double-layer tube sheet with the outer tube sheet welding groove 22 already turned is turned over to the other side, and the outer circle and end face turned in the previous step are aligned, and the end face runout is controlled within 0.02mm, and the inner tube sheet welding groove 12 is turned. At the same time, the cutting depth and feed amount are controlled during turning to prevent the tube sheet from being deformed due to excessive cutting force.
[0033] Through step 2 to step 5, the precise inner tube sheet welding groove 12 and the outer tube sheet welding groove 22 are turned out, so as to achieve the coaxiality between the inner and outer tube sheet tube holes 21 and the precise welding grooves.
[0034] like Figure 3 , Figure 4As shown; further, in step 6, firstly, a guide cone pin is used to pass through the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 of the double-layer tube sheet and the welding back plate tube hole 131; then, a positioning straight pin 5 having a diameter smaller than the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 is used to correct the coaxiality and locate the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21; if it is unqualified, the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21 are readjusted until the tube hole coaxiality test is qualified. In a specific implementation, the side of the inner tube sheet 1 away from the inner tube sheet welding groove 12 is a plane. The welding back plate 13 is arranged on the side of the inner tube sheet 1 away from the inner tube sheet welding groove 12. The welding back plate tube hole 131 of the welding back plate 13 corresponds to the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21, and the diameter of the welding back plate tube hole 131 is slightly larger than the inner tube sheet tube hole 11 and the outer tube sheet tube hole 21. The welding back plate tube hole 131, the inner tube plate tube hole 11 and the outer tube plate tube hole 21 are arranged in sequence from top to bottom, and the guide cone pin is inserted into the welding back plate tube hole 131, the inner tube plate tube hole 11 and the welding back plate tube hole 131 from top to bottom.
[0035] like Figure 4 As shown, further, in step 7, when the precision weld 3 is welded between the inner tube sheet 1 and the outer tube sheet 2 of the double-layer tube sheet, a welding back plate 13 is arranged on the side of the inner tube sheet 1 away from the outer tube sheet 2; the inner tube sheet 1, the outer tube sheet 2 and the welding back plate 13 are detachably fixedly connected by a plurality of spaced downward pressing rod assemblies; the inner tube sheet 1 and the welding back plate 13 are detachably fixedly connected by a plurality of spaced upward pulling rod assemblies 7. In a specific implementation, by tightly connecting the inner tube sheet 1 and the welding back plate 13 together, the rigidity during welding is improved, and the welding deformation is reduced, thereby improving the manufacturing accuracy of the welded double-layer tube sheet.
[0036] like Figure 4 As shown, the push rod assembly is a stud bolt 6, which is composed of a stud screw, two nuts 73 and a plurality of washers 41. In a specific implementation, one end of the stud screw passes through the outer tube sheet tube hole 21 at the lower part, and is installed with washers 41 and nuts 73; the other end thereof passes through the inner tube sheet tube hole 11 at the upper part and the uppermost welding back plate tube hole 131, and is installed with washers 41 and nuts 73. The inner tube sheet 1, the outer tube sheet 2 and the welding back plate 13 are fixed together by the push rod assembly.
[0037] like Figure 5As shown, the upper pull rod assembly 7 is composed of a single-head screw 71 with a square head or a hexagonal head having an eccentric step, a positioning sleeve 72 and a nut 73. In a specific implementation, one end of the single-head screw 71 with an eccentric step is set at one end of the inner tube sheet tube hole 11, and the threaded end of the single-head screw 71 passes through the inner tube sheet tube hole 11 and the welding back plate tube hole 131, and then the positioning sleeve 72 and the nut 73 are installed. The upper pull rod assembly 7 precisely connects the thinner inner tube sheet 1 and the welding back plate 13 together, thereby improving the rigidity during welding and reducing welding deformation.
[0038] Furthermore, in step 8, after the precision weld 3 is welded between the inner tube sheet 1 and the outer tube sheet 2 of the double-layer tube sheet, the tube hole coaxiality test is performed after welding. If the tube cannot be inserted, additional reaming is required until the tube hole coaxiality test can be passed, and then the tube hole is inserted. The use of this technical measure can improve the manufacturing accuracy of the welded double-layer tube sheet.
[0039] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.
Claims
1. A method for improving the manufacturing accuracy of a welded double-layer tube sheet, characterized in that: The following steps are involved: Step 1, respectively rough turning, fine turning and drilling the inner tube sheet and the outer tube sheet in the double-layer tube sheet; Step 2, the inner tube sheet and the outer tube sheet are arranged back to back, and after the tube holes of the inner tube sheet and the outer tube sheet are aligned, they are fixed together by fasteners; Step 3: Place the fixed double-layer tube sheets on a lathe for alignment; Step 4: After the alignment is completed, turn the welding groove of one tube sheet, and use the outer circle to turn the welding groove of the other tube sheet to find the alignment reference; Step 5, turn over the double-layer tube sheet and align it with the outer circle and end face turned in step 4, and turn the welding groove of the other tube sheet; Step 6, performing tube hole coaxiality detection on the inner tube sheet and the outer tube sheet in the double-layer tube sheet; Step 7: After the tube hole coaxiality test is qualified, the double-layer tube sheet is precisely welded; Step 8: Pipe through the hole.
2. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 1, characterized in that: In step 2, when the inner tube sheet and the outer tube sheet are arranged back to back, First, place a gasket in the cavity between the inner tube sheet and the outer tube sheet at the same height as the cavity; Then use the guide cone pin to guide the inner tube sheet hole and the outer tube sheet hole to assemble concentrically; Then, a plurality of positioning direct pins are used to correct the coaxiality of the tube holes of the inner tube sheet and the outer tube sheet and to fix the relative positions of the inner and outer tube sheets.
3. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 2, characterized in that: In step 2, a plug gauge smaller than the tube hole is used to detect whether the coaxiality of the tube hole of the inner tube sheet and the tube hole of the outer tube sheet is qualified; If it is unqualified, readjust the position of the inner tube sheet and the outer tube sheet until the tube hole coaxiality test is qualified; Then, multiple stud bolts matched with the tube holes of the inner tube sheet and the tube holes of the outer tube sheet are used to evenly compress the inner tube sheet and the outer tube sheet.
4. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 2, characterized in that: The diameter of the positioning straight pin is 0.02-0.05 mm smaller than the diameter of the tube hole.
5. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 1, characterized in that: In step 6, a guide cone pin is first used to pass through the inner tube sheet tube hole and the outer tube sheet tube hole of the double-layer tube sheet and the tube hole of the welding back plate; Then use a positioning straight pin with a diameter smaller than the diameter of the inner tube sheet hole and the outer tube sheet hole to correct the coaxiality and locate the position of the inner tube sheet hole and the outer tube sheet hole; if it is unqualified, readjust the position of the inner tube sheet hole and the outer tube sheet hole until the tube hole coaxiality test is qualified.
6. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 1, characterized in that: In step 7, when precision welding is performed between the inner tube sheet and the outer tube sheet of the double-layer tube sheet, A welding back plate is arranged on the side of the inner tube plate away from the outer tube plate; the inner tube plate, the outer tube plate and the welding back plate are detachably fixedly connected by a plurality of spaced downward push rod assemblies; the inner tube plate and the welding back plate are detachably fixedly connected by a plurality of spaced upward pull rod assemblies.
7. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 5 or 6, characterized in that: The tube holes of the welding back plate correspond to the tube holes of the inner tube plate and the outer tube plate, and the diameter of the tube holes of the welding back plate is slightly larger than the tube holes of the inner tube plate and the outer tube plate.
8. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 6, characterized in that: The push-down pull rod assembly is a stud bolt.
9. The method for improving the manufacturing accuracy of welded double-layer tube sheets according to claim 6, characterized in that: The pull rod assembly is composed of a single-head screw rod with a square head or a hexagonal head and an eccentric cylindrical step, a positioning bushing and a nut.