A split-structured lightweight and high-strength civil air defense door with a leveling device and its manufacturing method

Abstract

A split - type lightweight and high - strength civil air defense door with a leveling device and its manufacturing method. It is designed to be split - type, assembled by an upper part and a lower part, and is equipped with a leveling device. It includes an upper inner panel and an upper outer panel, the door leaf side channel steels around; a lower inner panel and a lower outer panel, the door leaf side channel steels around; there is an intermediate outer panel at the splicing position of the upper part and the lower part, and the leveling device is installed on the intermediate outer panel. The leveling device includes a jack with a bracket connected above, and both ends of the bracket extend to the upper outer panel and the lower outer panel respectively. The door leaf of the present invention is designed to be split - type, which solves the problem of large volume and is convenient for transportation; at the same time, a leveling device is designed. Through the leveling device for adjustment and compaction, the panel is closely attached to the skeleton for shaping, which solves the shortcoming that it is difficult to remedy in the prior art after the product production is formed, making the flatness of the fitting surface of the door leaf not exceed the standard allowable range, and optimizing the installation process and quality control process of the steel - structure door leaf.

Description

Technical Field

[0001] The present invention relates to the field of civil air defense engineering, and particularly to a split-type lightweight and high-strength civil air defense door with a leveling device and a manufacturing method thereof. Background Art

[0002] The protective equipment for civil air defense engineering refers to various equipment installed at various orifice parts of civil air defense engineering to block or weaken the killing and destructive effects of weapons from entering the interior of the project and ensure the safety inside the project. The protective equipment is usually installed at the orifice of the project and is an important part of the overall protective system of the protective project.

[0003] The protective equipment for civil air defense engineering (excluding valves) usually consists of four major parts: a doorframe, a door leaf, a locking device, and a hinge mechanism. Due to the variety of protective equipment, taking the most common and widely used steel structure door as an example, the door leaf adopts a flat structure form with a steel skeleton inside and a steel plate covered outside. As the orifice of the protective project becomes larger and larger, there are more and more super-large-sized protective equipment, such as subway interval partition doors, due to problems such as being too large in volume and unable to be transported as a whole due to on-site restrictions. The main functions of the door leaf include: resisting shock wave loads, achieving airtight functions, being able to open and close conveniently, providing installation positions for accessory mechanisms, etc.

[0004] In order to ensure the above functions of the doorframe, the following four aspects must be grasped during the production process:

[0005] Ensure that the door leaf has sufficient structural strength; ensure that the mating surface between the door leaf and the doorframe is flat; the welds at the seal strip embedding plate and the middle rubber strip groove should be fully welded; the opening positions at various places should be accurate.

[0006] In the actual assembly practice at the construction site, it is difficult to meet the above technological requirements. After the door leaf is processed and formed, it is extremely easy to have deformation conditions, and the remedy is complex, consuming human and material resources. During the welding process of the middle panel of the door leaf in the final process, deformation is likely to occur due to internal stress, etc. In relevant specifications such as the "Quality Inspection and Construction Acceptance Standards for Protective Equipment Products of Civil Air Defense Engineering" (RFJ01-2002) and the "Quality Acceptance and Evaluation Standards for Civil Air Defense Engineering" (RFJ01-2015), clear requirements are made for the flatness of the door leaf of the protective equipment, and there are certain difficulties in actual on-site operations. At the same time, in the production and manufacturing of civil air defense doors, there is a lack of a production process for adjustable deformation of the door leaf, and the installation process and production quality control process of steel structure door leaves need to be optimized urgently.

[0007] The structure of protective equipment is constantly improving and developing. At present, the research on protective equipment has shifted from initially focusing on improving resistance to lightweight design of the structure. To achieve lightweight of the protective door while meeting the requirements of technical and tactical indicators, simply changing the material type is difficult to meet the design requirements. While adopting new materials, corresponding lightweight and high-strength structures should be used. For example, various sandwich structures such as honeycomb structure, grid structure, and lattice structure can be explored for the feasibility of the door leaf structure. The structural improvement realizes buffering and energy absorption, being lightweight and high-strength. Summary of the Invention

[0008] The present invention provides a split-type civil air defense door with a leveling device and a manufacturing method thereof, which realizes split processing and transportation, enables the panel and the skeleton to be closely attached for shaping, and meets the product quality requirements.

[0009] A split-type civil air defense door with a leveling device according to the present invention has a split design for the door leaf. The door leaf is assembled by an upper part and a lower part and is provided with a leveling device. The upper part is assembled by an upper inner panel and an upper outer panel arranged oppositely and the door leaf side channel steels around. The lower part is assembled by a lower inner panel and a lower outer panel arranged oppositely and the door leaf side channel steels around. An intermediate outer panel is provided at the joint of the upper part and the lower part. The leveling device is installed on the intermediate outer panel. The leveling device includes at least two jacks. A bracket is commonly connected above the jacks. The two ends of the bracket respectively extend above the upper outer panel and the lower outer panel. A bracket foot is provided at each of the two ends of the bracket and is respectively connected to the upper outer panel and the lower outer panel.

[0010] Further, butt bolt holes and positioning pins are opened on the bottom side channel steel of the upper part and the top side channel steel of the lower part. The two channel steels are welded and the deformation is corrected to achieve leveling butt joint. The butt bolt holes are fixedly connected by bolts with spring washers to form a joint. An intermediate outer panel and an intermediate inner panel are laid outside the joint. Door leaf side channel steels are provided on both sides of the joint.

[0011] Further, door leaf I-beams are provided in the side channel steels on both sides of the door leaf. The I-beams are evenly spaced. The side channel steels and the I-beams form a steel skeleton grid beam structure.

[0012] Further, the butt bolt holes are symmetrically arranged up and down, and 4 groups of butt bolt holes are opened up and down respectively. The positioning pins are symmetrically arranged left and right on the center line, and 2 positioning pins are opened. The positioning pins are internal thread taper pins.

[0013] Furthermore, no less than two groups of foam aluminum filled tube buffering energy absorbing structures are used to replace the steel frame in the middle of the door leaf. The foam aluminum filled tube buffering energy absorbing structures are distributed in an equidistant array. The foam aluminum filled tube buffering energy absorbing structures include a top plate, a bottom plate and a thin-walled circular tube in the middle. The thin-walled circular tube is glued to the middle of the top plate and the bottom plate and then connected to the top plate and the bottom plate with bolts. The top plate is made of high-strength steel plate, and the bottom plate is made of low-carbon steel. The thin-walled circular tube is made of aluminum or low-carbon steel, and is filled with polymer porous foam. The polymer porous foam is made of one or more of polyurethane foam, polystyrene foam plastic, and polyethylene foam plastic.

[0014] The present invention provides a method for manufacturing a split-structure civil air defense door with a leveling device, comprising the following steps:

[0015] S1. Cutting: Check the appearance and ends of channel steel and I-beam to see if there are warping, unevenness, dead bend, heavy skin, cracks, cut and straighten them, use negative tolerance for processing size, and when cutting inner and outer panels, the cutting nozzle should be perpendicular to the panel surface;

[0016] S2. Drill the plug welding holes of the inner and outer panels. When processing the plug welding holes of the inner and outer panels, first mark the spacing of the door frame. When the panels are spliced, add a row of plug welding holes at the splicing seams. After passing the inspection, use a rocker drill to drill the plug welding holes. The plug welding holes are processed by a drilling machine.

[0017] S3, assemble and weld the frame; spot weld the outer frame of the channel steel on the platform, use a square ruler to measure to ensure that the channel steel and the platform are 90 degrees, place the I-beam, the butt gap is ≤ 2mm, weld, and after the frame is formed, the allowable deviation of the frame height is +2mm;

[0018] S4. Assemble and weld the panels to form the upper and lower door leaves; when assembling and welding the outer panels, first spot weld the frame and the outer panels together, and make sure the panels fit tightly with the frame. Weld according to the welding requirements of the drawings. After passing the inspection, proceed to the next process, otherwise rework will be required; when assembling and welding the inner panels, diffuse the welding plug points from the center to the surrounding areas, and finally use a linear trolley welding machine to weld the welds on the four sides, assemble the embedded pressure plate, and polish the welds to make them smooth; when splicing the inner and outer panels, an automatic submerged arc welding machine must be used for welding, and the joints should be on the frame. When welding, ensure that the welding wire is in the center of the weld, and after the weld is formed, it must not be lower than the plate surface;

[0019] S5. Splice the upper and lower door leaves; the two middle channel steels must be connected with bolts first, then the channel steel I-beams are welded into a frame, and then the inner and outer panels are welded; after the door leaves are welded, the inner and outer surfaces are flat, and the flatness tolerance and the adjacent edge verticality tolerance are both 2mm; the upper and lower door leaves and door frames are assembled at the construction site with positioning pins and docking bolts. After assembly, ensure that the fitting surface is flat, with a flatness tolerance of 2mm;

[0020] S6. Weld the middle panel and shape it; the inner middle panel and the outer panel are welded on-site. After the door leaf is formed, it is deformed. Use the leveling device pre-installed on the middle panel and press it with a jack to make the panel fit tightly against the skeleton, and then weld it in sections in sequence to make the flatness of the fitting surface of the door leaf reach the standard allowable range.

[0021] Further, the allowable deviation range for cutting the inner panel and the outer panel is as follows: when the panel width is ≥ 1000 mm and ≤ 2000 mm, the allowable deviation range is ±1 mm, and the string angle ≤ 2 mm; when the panel width is > 2000 mm and ≤ 3500 mm, the allowable deviation range is ±2 mm, and the string angle ≤ 3 mm.

[0022] Further, the allowable deviation of the width of the door leaf panel skeleton is as follows: when the skeleton width is ≥ 1000 mm and ≤ 2000 mm, the allowable deviation range is +1 mm; when the skeleton width is > 2000 mm and ≤ 3500 mm, the allowable deviation range is +2 mm; when the skeleton width is > 3500 mm and ≤ 4500 mm, the allowable deviation range is +3 mm.

[0023] Further, the specific steps of step S3 include:

[0024] S31. Lay out the full-size pattern on the working platform according to the door leaf drawing, and then lay the I-beams and channel steels respectively according to the full-size pattern and make rigid fixation;

[0025] S32. Cut the required round holes and square holes respectively with a profiling cutting machine, and perform secondary treatment on the cut edges to remove burrs and rust;

[0026] S33. Use the production platform for positioning and group welding. Tighten all welding seams. If the gap exceeds 1 mm, then perform fixed welding. At both ends of the wing plate of each joint, spot weld 20 mm at the flat welding position, and spot weld 30 - 40 mm in the middle on both sides of the web;

[0027] S34. Welding of the skeleton composed of channel steel and I-beam: When welding the skeleton, skip welding should be carried out from the middle to the surrounding. The door leaf should be divided into 4 equal areas, and 4 welders should perform skip welding from the middle to the surrounding of each area respectively;

[0028] Press each component tightly against the positioning block on the platform, control the perpendicularity of the component to the positioning block to be no greater than 2 mm, and the flatness to be less than 1.5 mm. First, perform spot welding. After checking that the dimensions of each part are correct, weld them in sequence from the inside to the outside according to the process standard to make the welding internal stress release outward by itself;

[0029] The welding sequence is: first weld the flat welds of the lower flanges of each grid area. After all are welded and cooled, then weld the fillet welds of the transverse I-beam web and the lower flange of the longitudinal I-beam, and finally weld the butt flat welds of the upper flanges;

[0030] When the inner panel is welded to the skeleton, it should be closely attached, and the welding seams should be carried out in the order of intermittent welding and segmented welding;

[0031] When plug welding the panel to the skeleton, use a jack to press it firmly, and then carry out the welding in the order of zoning and segmentation. First, position-weld a hole at an interval of 500 - 600 mm to connect the skeleton and the inner panel;

[0032] To control the deformation of the door leaf, it is required that the joints of the panel must be opened with V-shaped grooves, welded on both sides and the joints are on the I-beam;

[0033] Press the outer panel tightly against the skeleton, with the gap not exceeding 1 mm; carry out spot welding from the middle to the surrounding, with the interval not exceeding 400 mm, and the weld length is generally 30 - 50 mm; after the spot welding is completed, use staggered intermittent welds. First, weld the longitudinal I-beams and channels, and finally weld the transverse I-beams;

[0034] Divide the inner panel into 4 areas, and 4 welders carry out skip welding at a distance of 800 - 1000 mm. Each welding hole is welded in three layers, and the temperature of each welding layer is controlled at 80 °C. After all the first layers of welding holes are welded, then weld the second layer, and after the second layer is welded, then weld the third layer;

[0035] For the welding of the panel and the surrounding channels of the skeleton, divide the perimeter of the door leaf frame into multiple equal parts at about 500 - 600 mm, and four welders carry out skip welding from the middle to both ends on the four seams;

[0036] After all parts are adjusted, weld the outer panel. Drill and plug weld the outer panel, and finally carry out the welding around. Since the outer dimension of the door leaf is large, when the panel joints are opened with V-shaped grooves and welded on both sides, the weld seams must be on the I-beam. To reduce deformation, use the methods of simultaneous symmetric welding and segmented reverse welding;

[0037] After the grid skeleton is welded, adjust the flatness, then lay the panel on the I-beam skeleton and hold it firmly with a jack;

[0038] S35. The appearance quality of the weld seams is measured by a weld seam angle gauge, measure the weld seam thickness, weld seam reinforcement and observe the cleaning conditions of weld seam slag inclusions, pores, and weld beads. Quality inspectors use a measuring instrument to check the dimensions and control the errors;

[0039] Deal with unqualified welding areas and use an ultrasonic flaw detector to detect the weld seam quality;

[0040] S36. Add reinforcing plates and connecting angle steels for fixation to reduce the degree of deformation;

[0041] S37. Before welding the outer panel, spray two coats of anti-rust paint inside the skeleton, then assemble the locking mechanism components inside the door leaf, and carry out the flatness debugging of the lock, and lubricate each rotating part with oil.

[0042] Further, the specific steps of step S4 include:

[0043] In the welding process of the outer panel and the skeleton:

[0044] S41. Before welding, open small protective door holes on the outer panel. Place the spliced and aligned outer panel flat on the platform, then lift and place the steel skeleton on it. Assemble it according to the dimensions required by the drawing and then spot weld for positioning in the middle of the door leaf.

[0045] S42. Positioning welding: After the door leaf is positioned, use the gantry steel and pressure codes to press the skeleton and the outer panel tightly and check with a feeler gauge. The gap shall not exceed 1 mm. Then, perform positioning welding from the middle to the surrounding at intervals of 350 - 400 mm. The weld leg is 5 mm and the weld length is 30 - 50 mm.

[0046] S43. After the positioning welding is completed and all are cooled, perform skip welding from the middle longitudinal I-beam to both ends. After all the longitudinal I-beams are welded, then weld the inner side weld of the channel steel and the outer panel. The welding method is intermittent welding, the weld angle is 5 mm, the spacing is 50 mm, and the weld length is 50 mm.

[0047] S44. After welding the longitudinal I-beam, channel steel and the fillet weld of the panel, adopt the same method as in step S43 to weld the transverse I-beam, channel steel and the fillet weld of the outer panel.

[0048] In the welding process of the inner panel and the skeleton:

[0049] S441. Lay the inner panel with plug weld holes drilled, inspection holes opened and small protective door holes opened on the steel skeleton according to the specified dimensions. Weld 3 or 4 points by spot welding in the middle of the panel to position the panel and the steel skeleton. Then use the gantry to press from the middle to the surrounding to press the inner panel and the steel skeleton tightly, and the gap shall not be greater than 1 mm.

[0050] S442. After the panel is pressed tightly, weld the plug weld holes in three layers. For the first layer, weld a pair of plug weld holes at intervals of 500 - 600 mm from the middle of the door leaf to the surrounding to fix the whole panel and the skeleton according to this distance. The first layer of plug weld should be evenly welded in a circle along the root of the plug weld hole, and the welding thickness shall not exceed 5 mm. For the remaining plug weld holes, after checking the deformation of the door leaf, adjust the welding sequence according to the actual situation of the door leaf. Before performing the first layer of welding, the panel and the steel plate skeleton must be pressed tightly.

[0051] S443. After the first layer of plug welding of the panel is completed, divide the door leaf into four areas and perform skip welding from the middle of the door leaf to the surrounding at intervals of 8000 - 1000 mm until the second layer of all plug weld holes is welded, and then weld the third layer.

[0052] S444. Stress relief by hammering. Use a Type C6 pneumatic chisel for hammering. Grind the chisel head into a spherical round head with R = 5 mm. Ensure that the working pressure of the air source is 0.63 MPa. Hammering should be carried out immediately while the weld is still red-hot after each layer of weld is completed.

[0053] S445. Welding of the inner and outer panels to the peripheral channel steel of the steel skeleton: Press the edge seams tightly. Divide the lengths of the four sides of the door leaf into equal parts of 500 - 600 mm. Weld in a skip pattern from the middle of each side length to both ends until all welding is completed.

[0054] S446. Welding of the middle rubber strip groove is carried out according to the welding procedure of the airtight groove support plate of the door frame.

[0055] A split - type lightweight and high - strength civil air defense door with a leveling device provided by the present invention, compared with the prior art, when the size of the door leaf of the civil air defense door is relatively large, the door leaf is designed as a split type, divided into upper and lower parts, which is convenient for transportation. At the same time, a leveling device is designed. After the door leaf is processed and formed, during the on - site assembly process, the middle panel is left for on - site welding. During the welding process, if deformation occurs, it is adjusted and compacted through the leveling device, and the panel is shaped by making it fit tightly with the skeleton, solving the drawback in the prior art that it is difficult to remedy after the product production is formed. The on - site assembly also solves the transportation problem, making the flatness of the fitting surface of the door leaf not exceed the standard allowable range, and optimizing the installation process and quality control process of the steel - structure door leaf.

[0056] The present invention also provides a manufacturing method for a split - type lightweight and high - strength civil air defense door with a leveling device, which strictly limits the production process. It gives a comprehensive design and detailed requirements for the product from blanking to plug - welding holes of the inner and outer panels, assembling and welding the skeleton, welding the panels to form the upper and lower door leaves, splicing the upper and lower door leaves, welding the middle panel and shaping, forming a systematic production line.

[0057] The present invention fills with aluminum foam and increases the density of aluminum foam, which can reduce the maximum displacement and improve the impact force and energy absorption of the aluminum - foam - filled tube buffer energy - dissipation structure. In addition, filling with aluminum foam can also avoid the sharp increase in impact force when the aluminum - foam - filled tube buffer energy - dissipation structure reaches densification. In addition, the aluminum - foam - filled tube buffer energy - dissipation structure shows higher energy - absorption capacity by specifying that the flat steel plate and the tubular core have similar thicknesses. At the same time, the aluminum - foam - filled tube buffer energy - dissipation structure replaces the steel skeleton, greatly reducing the weight of the product and achieving lightweight and high - strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a schematic structural diagram of the present invention;

[0059] Figure 2 is a side view of the present invention;

[0060] Figure 3Side view structural diagram of another embodiment of the present invention;

[0061] Figure 4 Enlarged sectional view structural diagram of part I (joint) in the attached drawings of the present invention;

[0062] Figure 5 Schematic diagram of the grooved steel structure at the joint between the upper part and the lower part of the present invention;

[0063] Figure 6 Schematic diagram of the buffer energy dissipation structure of the aluminum foam filled tube of the present invention;

[0064] In the figure: 1. Upper outer panel; 2. Upper inner panel; 3. Lower outer panel; 4. Lower inner panel; 5. Middle outer panel; 6. Door leaf side channel steel; 7. Door leaf body; 8. Leveling device; 81. Jack; 82. Bracket; 83. Bracket foot; 9. Door leaf I-beam; 10. Bottom side channel steel of the upper part; 11. Top side channel steel of the lower part; 12. Docking bolt hole; 13. Positioning pin; 14. Spring washer; 15. Buffer energy dissipation structure of aluminum foam filled tube; 151. Top plate; 152. Bottom plate; 153. Thin-walled round tube. Detailed implementation manners

[0065] Next, in combination with the attached drawings and the detailed implementation manners, the present invention will be further described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0066] With reference to Figure 1 and Figure 2, which are the structural schematic diagram and the side view structural schematic diagram of the present invention. The present invention provides a split-type lightweight and high-strength civil air defense door with a leveling device. The door leaf is designed to be split-type, and the split-type design means that the entire civil air defense door is composed of multiple parts, assembled by the upper part and the lower part, and a leveling device 8 is provided on the door leaf body 7. In this embodiment, the overall door leaf is a cuboid structure. The upper part is assembled by the upper inner panel 2 and the upper outer panel 1 arranged oppositely and the door leaf side channel steel 6 around. The lower part is assembled by the lower inner panel 4 and the lower outer panel 3 arranged oppositely and the door leaf side channel steel 6 around. An intermediate outer panel 5 is provided at the joint of the upper part and the lower part. The three parts together form the door leaf body 7. The leveling device 8 is installed on the intermediate outer panel 5. The leveling device 8 includes no less than two jacks 81, which are selected as three in this embodiment. The three jacks 81 are arranged collinearly and have the same height, and are leveled by an instrument to further ensure that the bracket 82 connected commonly above the support shaft of the jack 81 remains horizontal. In the present invention, the bracket 82 can be selected as other rigid horizontal steel plates and other structures, or can be selected as sections with higher levelness. The two ends of the bracket 82 respectively extend above the upper outer panel 1 and the lower outer panel 3. One bracket foot 83 is provided at each end of the bracket 82 and is respectively connected to the upper outer panel 1 and the lower outer panel 3, and the connection method can be selected as welding. In this embodiment, considering the difficulty of transporting the door leaf, the split design divides the panels into 6 pieces in total, namely the upper inner panel 2, the upper outer panel 1, the lower inner panel 4, the lower outer panel 3, the intermediate outer panel 5 and the intermediate inner panel, or can be reduced to 5 pieces excluding the intermediate inner panel, that is, the upper inner panel 2 and the lower inner panel 4 on the reverse side of the illustrated embodiment are directly welded and assembled.

[0067] Refer to the side view attachment Figure 2 , door leaf I-beams 9 are provided in the side channel steels on both sides of the door leaf body 7. The door leaf I-beams 9 are evenly spaced. The side channel steels on both sides of the door leaf body 7 and the door leaf I-beams 9 form a steel skeleton grid beam structure. The horizontal door leaf I-beams 9 are the main load-bearing members, and cooperate with the vertical I-beams of the side channel steels to form a grid beam, enhancing the strength of the civil air defense door structure of the present invention.

[0068] Refer to the attachment Figure 4 And the attachment Figure 5, is an enlarged sectional view structure diagram of the splicing part (Part I) of the present invention and a schematic diagram of the channel steel structure; butt bolt holes 12 are opened on the bottom side channel steel 10 of the upper part and the top side channel steel 11 of the lower part, and positioning pins 13 are opened. The butt bolt holes 12 are symmetrically arranged up and down. In this embodiment, 4 groups of butt bolt holes 12 are opened up and down; the positioning pins 13 are symmetrically arranged left and right on the center line, and 2 positioning pins 13 are opened. The positioning pins 13 are internal thread taper pins. In this embodiment, the two channel steels are welded and the deformation is corrected to achieve leveling butt joint. The butt bolt holes 12 are fixedly connected by bolts with spring washers 14 to form a splicing part; an intermediate outer panel 5 is laid outside the splicing part, and door leaf side channel steels are arranged on both sides of the splicing part.

[0069] Combined with reference to the attached Figure 3 And the attached Figure 6 , is a side view structure diagram of another embodiment of the present invention and a schematic diagram of the foam aluminum filled tube buffer energy dissipation structure 15. Based on the goal of lightweight and high strength of the protection equipment, in this embodiment, the steel skeleton inside the door leaf body 7 is no longer used, and no less than two groups of foam aluminum filled tube buffer energy dissipation structures 15 are selected to replace the steel skeleton in the middle of the door leaf. The foam aluminum filled tube buffer energy dissipation structures 15 are arranged in an equidistant array. In actual application, reasonable design can be carried out according to the product strength requirements. The foam aluminum filled tube buffer energy dissipation structure 15 includes a top plate 151, a bottom plate 152 and a thin-walled circular tube 153 in the middle. The thin-walled circular tube 153 is adhered to the middle of the top plate 151 and the bottom plate 152 and then the top plate 151 and the bottom plate 152 are connected by bolts. The top plate 151 is made of high-strength steel plate material, and the bottom plate 152 is made of low-carbon steel material. The size can be customized according to the requirements to obtain the best performance; the thin-walled circular tube 153 is made of aluminum or low-carbon steel material, and the inside is filled with polymer porous foam. The polymer porous foam is selected from one or several of polyurethane foam, polystyrene foam plastic, and polyethylene foam plastic. Filling foam aluminum and increasing the density of foam aluminum can reduce the maximum displacement and improve the impact force and energy absorption of the foam aluminum filled tube buffer energy dissipation structure 15. In addition, filling foam aluminum can also avoid the sharp increase of the impact force when the foam aluminum filled tube buffer energy dissipation structure 15 reaches densification. In addition, the foam aluminum filled tube buffer energy dissipation structure 15 shows higher energy absorption capacity by specifying that the flat steel plate and the tubular core have similar thicknesses.

[0070] The split-structure lightweight high-strength civil air defense door with a leveling device 8 of the present invention realizes that when the size of the civil air defense door leaf is large, the door leaf is designed to be split, divided into upper and lower parts, which is convenient for transportation; at the same time, a leveling device is designed, and after the door leaf is processed and formed, the middle panel is left for on-site welding during the on-site assembly process. If there is deformation during the welding process, the leveling device 8 is used to adjust and compact the panel and the frame to perform shaping, which solves the shortcomings of the prior art that the product has been formed and is difficult to remedy. The on-site assembly simultaneously solves the transportation problem, so that the flatness of the door leaf joint surface does not exceed the standard allowable range, and the installation process and quality control process of the steel structure door leaf are optimized.

[0071] The present invention also provides a method for manufacturing a split-structure lightweight high-strength civil air defense door with a leveling device, comprising the following steps:

[0072] S1. Cutting: Check the appearance and ends of channel steel and I-beam to see if there are defects such as warping, unevenness, dead bends, heavy skin, cracks, etc. Only after checking that they are correct can you mark the lines according to the drawing dimensions. Cut the transverse channel steel, transverse I-beam, longitudinal channel steel, and I-beam manually or with a steel cutting machine, then straighten them and ensure that the cut is square. The processing size preferably has a negative tolerance. When cutting the inner and outer panels, you can use a linear cutting machine to make the cut straight and the cutting nozzle perpendicular to the plate surface. Control the flame angle and the travel speed of the trolley to ensure the cut quality.

[0073] In this embodiment, it is recommended to use a shearing machine to cut the embedded pressure plate and the rubber strip groove, and the length and width dimensions should meet the requirements of the drawings. The cutting, drilling, punching, cutting and other processing of the steel structure door leaf should be processed according to the positive tolerance of the tolerance marked on the drawings.

[0074] The allowable deviation range of inner and outer panel cutting is as follows:

[0075] Panel width (A) Allowable deviation range (mm) 1000≤A≤2000 +1mm 2000＜A≤3500 +2mm

[0076] When the panel width is ≥1000mm and ≤2000mm, the allowable deviation range is ±1mm and the string angle is ≤2mm; when the panel width is >2000mm and ≤3500mm, the allowable deviation range is ±2mm and the string angle is ≤3mm.

[0077] S2. Drill plug welding holes on the inner and outer panels. When processing the plug welding holes on the inner and outer panels, first mark the distance between the door leaf frames. When splicing the panels, add a row of plug welding holes at the joints. After passing the inspection, use a radial drill to drill the plug welding holes. Use a drilling machine to process the plug welding holes, and do not use gas cutting.

[0078] S3. Assemble and weld the skeleton; spot weld the outer frame of the channel steel on the platform first, and use a square ruler to measure to ensure that the channel steel is 90 degrees with the platform. Place the I-beams according to the drawing size and the positions of the horizontal and vertical I-beams. The butt gap is ≤ 2mm. Flat iron and other objects shall not be placed in the weld gap to reduce the gap. Weld the horizontal and vertical I-beams and the rings. All welds meet the requirements of the drawings. After the skeleton is formed, the allowable deviation of the skeleton height is +2mm, and the allowable deviation of the width is shown in the following table:

[0079] Skeleton width (B) Allowable deviation range (mm) 1000≤B≤2000 +1mm 2000＜B≤3500 +2mm 3500＜B≤4500 +3mm

[0080] The allowable deviation of the door panel frame width is: when the frame width is ≥1000mm and ≤2000mm, the allowable deviation range is +1mm; when the frame width is >2000mm and ≤3500mm, the allowable deviation range is +2mm; when the frame width is >3500mm and ≤4500mm, the allowable deviation range is +3mm.

[0081] Step S3 specifically includes:

[0082] S31. Lay out the large pattern on the working platform according to the door leaf drawing, and then lay the I-beams and channel steels according to the large pattern for rigid fixation; cut and process according to the drawing, cut the channel steels and I-beams as required, and cut them with a linear cutting machine.

[0083] S32. Cut the required round holes and square holes with a contour cutting machine, and perform secondary treatment on the cut edges to remove burrs and rust. During assembly welding, strictly follow the compiled process flow, and require operators to master the process in the form of a blackboard report, unify the steps, and then implement them.

[0084] S33. Use the production platform for positioning and welding. The welding of each positioning block is strictly carried out according to the standard to ensure the processing accuracy of the door leaf. Each welding seam is tight and the local gap exceeds 1mm. This is an effective way to reduce welding deformation. Then fix welding is performed. The two ends of each joint wing plate are spot welded 20mm at the flat welding position, and the middle of the two sides of the web are spot welded 30~40mm.

[0085] S34. Frame welding composed of channel steel and I-beam: When welding the frame, the welding should be done from the middle to the surrounding areas. The door leaf should be divided into 4 equal areas, and 4 welders should weld from the middle to the surrounding areas of each area.

[0086] Place each component close to the positioning block on the platform, control the verticality between the component and the positioning block to be no more than 2mm, and the flatness to be less than 1.5mm, spot weld first, and after checking the dimensions of each part to make sure they are correct, weld them from the inside to the outside in sequence according to the process standards, so that the internal stress of the welding can be released outwards by itself.

[0087] The welding sequence is as follows: First, weld the flat welds of the lower flanges of each grid area. After all are welded and cooled, then weld the fillet welds of the transverse I-beam webs and the lower flanges of the longitudinal I-beams. Finally, weld the butt flat welds of the upper flanges.

[0088] When the inner panel is welded to the skeleton, it should be closely attached. The welding seams are carried out in the order of intermittent welding and segmented welding.

[0089] When the outer panel is welded to the skeleton by plug welding, a jack must be used to press it firmly to make the panel closely attached to the skeleton. Then, it is carried out in the order of welding in sections and areas. First, position weld a hole at an interval of 500 - 600 mm to connect the skeleton and the inner panel.

[0090] To control the deformation of the door leaf, it is required that the joints of the panel must be opened with V-shaped grooves, welded on both sides, and the joints are on the I-beams.

[0091] Press the outer panel and the skeleton firmly, and the gap does not exceed 1 mm; carry out spot welding from the middle to the surrounding, with an interval not exceeding 400 mm, and the weld length is generally 30 - 50 mm; after spot welding is completed, use staggered intermittent welds. First, weld the longitudinal I-beams and channels, and finally weld the transverse I-beams.

[0092] Divide the inner panel into 4 areas, and 4 welders weld in a skip welding manner at a distance of 800 - 1000 mm. Each welding hole is welded in three layers, and the temperature of each welding layer is controlled at 80 °C. After all the first layers of the welding holes are welded, then weld the second layer, and after the second layer is welded, then weld the third layer.

[0093] When a welding hole is welded for one layer, it should be hammered immediately while it is in a red-hot state. In principle, one welder is paired with one person for hammering until the surface is shiny.

[0094] For the welding of the panel and the surrounding channels of the skeleton, divide the perimeter of the door leaf frame into multiple equal parts at about 500 - 600 mm, and 4 welders carry out skip welding from the middle to both ends on the four seams.

[0095] After all parts are adjusted, weld the outer panel. Drill holes for plug welding on the outer panel, and finally carry out welding around. Since the outer dimension of the door leaf is relatively large and the joints of the panel are opened with V-shaped grooves and welded on both sides, the weld seams must be on the I-beams. To reduce deformation, the methods of simultaneous symmetric welding and segmented reverse welding are adopted.

[0096] After the grid skeleton is welded, adjust the flatness, and then lay the panel on the I-beam skeleton and fasten it firmly with a jack.

[0097] S35. The appearance quality of the weld seams is measured by a weld seam angle gauge, measuring the weld seam thickness, weld seam reinforcement, and observing the cleaning conditions of weld seam slag inclusions, pores, and weld beads. Quality inspection personnel use a measuring instrument to check the dimensions and control the errors.

[0098] After dealing with the unqualified welding areas, use an ultrasonic flaw detector to detect the weld seam quality.

[0099] S36. Because the outer panel has a concealed locking installation and debugging inspection hole, the strength of the steel plate is greatly affected. During the installation and debugging process, multiple moves and flipping of the door leaf can easily cause deformation. Therefore, control measures are taken to increase reinforcement plates and connect angle steels for fixation to reduce the degree of deformation.

[0100] S37. Before welding the outer panel, spray the inside of the frame with two coats of anti-rust paint, then assemble the locking mechanism components inside the door leaf, perform plane adjustment for locking, and lubricate each rotating part with oil.

[0101] S4. Assemble and weld the panels to form the upper and lower door leaves; when assembling and welding the outer panels, first spot weld the frame and the outer panels together, and make sure the panels fit tightly against the frame. Weld according to the welding requirements in the drawing, and proceed to the next process after passing the inspection, otherwise rework will be required; when assembling and welding the inner panels, diffuse the welding plug points from the center to the surrounding areas, and finally use a linear trolley welding machine to weld the welds on all four sides, assemble the embedded pressure plates, and polish the welds until smooth; when splicing the inner and outer panels, an automatic submerged arc welding machine must be used for welding, and the joints should be on the frame. When welding, ensure that the welding wire is in the center of the weld, and the weld must not be lower than the panel surface after formation.

[0102] Step S4 specifically includes: In the welding procedure of the outer panel and the frame:

[0103] S41. Before welding, make a small protective door hole on the outer panel, place the spliced ​​and calibrated outer panel flat on the platform, then hang the steel frame on it, align the dimensions according to the drawing requirements, and then spot weld in the middle of the door leaf to position it.

[0104] S42. Positioning welding: After the door leaf is positioned, use gantry steel and pressure weights to press the frame and the outer panel tightly. Check with a feeler gauge that the gap does not exceed 1mm. Then, at a spacing of 350-400mm, position welding is performed from the middle to the surrounding areas. The weld foot is 5mm and the weld length is 30-50mm.

[0105] S43. After positioning welding is completed and all the parts have cooled down, perform jump welding from the middle longitudinal I-beam to both ends. After all the longitudinal I-beams have been welded, weld the channel steel and the inner weld of the outer panel. The welding method is intermittent welding, with a welding angle of 5mm, a spacing of 50mm, and a weld length of 50mm.

[0106] S44, after the longitudinal I-beam, channel steel and panel fillet welds are welded, the transverse I-beam, channel steel and outer panel fillet welds are welded in the same manner as step S43.

[0107] Inner panel and frame welding procedure:

[0108] S441. Lay the inner panel with drilled plug weld holes, opened inspection holes and small protective door holes on the steel skeleton according to the specified dimensions, weld 3 or 4 points in the middle of the panel by spot welding to position the panel and the steel skeleton; then use a gantry to press from the middle to the surrounding to press the inner panel and the steel skeleton tightly, and the gap shall not be greater than 1 mm.

[0109] S442. After the panel is pressed tightly, the plug weld holes are welded in three layers; for the first layer, weld a pair of plug weld holes at intervals of 500 - 600 mm from the middle of the door leaf to the surrounding, and fix the entire panel and the skeleton according to this distance; the first layer of plug welds shall be evenly welded in a circle along the root of the plug weld hole, and the welding thickness shall not exceed 5 mm; for the remaining plug weld holes, after checking the deformation of the door leaf, adjust the welding sequence according to the actual situation of the door leaf. Before applying the first layer of welding, the panel and the steel plate skeleton must be pressed tightly.

[0110] S443. After the first layer of plug welding of the panel is completed, divide the door leaf into four areas and perform skip welding from the middle of the door leaf to the surrounding at intervals of 8000 - 1000 mm until the second layer of all plug weld holes is welded, and then weld the third layer.

[0111] S444. Hammer to eliminate stress. Use a C6 type pneumatic chisel for hammering. Grind the chisel head into a spherical round head with R = 5 mm, and ensure that the working pressure of the air source is 0.63 MPa; hammering should be carried out immediately while the welds of each layer are still in a red-hot state after welding.

[0112] S445. Welding of the inner and outer panels and the peripheral channel steel of the steel skeleton: Press the side seams tightly, divide the equal parts of 500 - 600 mm according to the lengths of the four sides of the door leaf; perform skip welding from the middle of the side length to both ends until all are welded.

[0113] S446. Weld the middle rubber strip groove according to the welding procedure of the support plate of the airtight groove of the door frame.

[0114] S5. Splice the upper and lower door leaves; first connect the two middle channel steels with bolts, then weld the channel steel and I-beam into a frame, and then weld the inner panel and the outer panel; after the door leaf is assembled and welded, the inner and outer surfaces are flat, and the flatness tolerance and the perpendicularity tolerance of the adjacent sides are both 2 mm; the upper and lower door leaves and the door frame are assembled with positioning pins 13 and butt bolts at the construction site. After assembly, ensure that the mating surface is flat and the flatness tolerance is 2 mm.

[0115] S6. Weld the middle panel and shape it; the middle inner panel and the middle outer panel 5 are welded on site. After the door leaf is formed, there is deformation. Use the leveling device 8 pre-installed on the middle panel and press it with a jack 81 to make the panel fit tightly with the skeleton, and then carry out the welding sequence by dividing into areas and sections to make the flatness of the mating surface of the door leaf reach the standard allowable range.

[0116] A manufacturing method of a split - type lightweight and high - strength civil air defense door with a leveling device 8 according to the present invention strictly restricts the production process. It gives an all - round design for this product from blanking to plug - welding holes on the inner and outer panels, assembling and welding the skeleton, welding the panels to form the upper and lower door leaves, splicing the upper and lower door leaves, welding the middle panel and shaping, and puts forward detailed requirements to form a systematic production line.

[0117] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A split-structured lightweight and high-strength civil air defense door with a leveling device, characterized in that The door leaf is designed to be split-type. The door leaf is assembled by an upper part and a lower part and is provided with a leveling device. The upper part is assembled by an upper inner panel and an upper outer panel arranged oppositely and the door leaf side channel steels around. The lower part is assembled by a lower inner panel and a lower outer panel arranged oppositely and the door leaf side channel steels around. An intermediate outer panel is provided at the splicing position of the upper part and the lower part. The leveling device is installed on the intermediate outer panel. The leveling device includes not less than two jacks. A bracket is commonly connected above the jacks. Two ends of the bracket respectively extend above the upper outer panel and the lower outer panel. A bracket foot is arranged at each of the two ends of the bracket and is respectively connected with the upper outer panel and the lower outer panel.

2. The split-type lightweight and high-strength civil air defense door with a leveling device according to claim 1, wherein Butt bolt holes and positioning pins are opened on the bottom side channel steel of the upper part and the top side channel steel of the lower part. The two channel steels are welded and the deformation is corrected to achieve leveling butt joint. The butt bolt holes are fixedly connected by bolts with spring washers to form a splicing position. The intermediate outer panel is laid outside the splicing position. Door leaf side channel steels are provided on both sides of the splicing position.

3. The split-type lightweight and high-strength civil air defense door with a leveling device according to claim 1 or 2, characterized in that Door leaf I-beams are arranged in the side channel steels on both sides of the door leaf. The I-beams are evenly spaced. The side channel steels and the I-beams form a steel skeleton grid beam structure.

4. The split-type lightweight and high-strength civil air defense door with a leveling device according to claim 2, wherein, The butt bolt holes are symmetrically arranged up and down. 4 groups of butt bolt holes are opened up and down respectively. The positioning pins are symmetrically arranged left and right on the center line. 2 positioning pins are opened. The positioning pins are internal thread taper pins.

5. The split-structured lightweight and high-strength civil air defense door with a leveling device according to any one of claims 1, 2 or 4, characterized in that Use not less than two groups of aluminum foam filling tube buffer energy dissipation structures to replace the steel section skeleton in the middle of the door leaf. The aluminum foam filling tube buffer energy dissipation structures are arranged in an equidistant array. The aluminum foam filling tube buffer energy dissipation structure includes a top plate, a bottom plate and a thin-walled circular tube in the middle. The thin-walled circular tube is glued to the middle of the top plate and the bottom plate and then the top plate and the bottom plate are connected by bolts. The top plate is made of high-strength steel plate. The bottom plate is made of low-carbon steel. The thin-walled circular tube is made of aluminum or low-carbon steel and is filled with polymer porous foam inside. The polymer porous foam is selected from one or several of polyurethane foam, polystyrene foam plastic and polyethylene foam plastic.

6. A manufacturing method of a split - type lightweight and high - strength civil air defense door with a leveling device, which is applied to the split - type lightweight and high - strength civil air defense door with a leveling device according to any one of claims 1 to 5, characterized in that, It includes the following steps: S1. Cutting: Check the appearance and the ends of the channel steel and I-beam for defects such as warping, unevenness, dead bend, double skin and crack. Cut and straighten. The processing dimension selects negative tolerance. During the cutting of the inner panel and the outer panel, the cutting nozzle is perpendicular to the panel surface. S2. Drilling plug weld holes on the inner panel and the outer panel: When processing the plug weld holes on the inner panel and the outer panel, first draw lines according to the door leaf skeleton spacing. When splicing the panels, an additional row of plug weld holes is added at the splicing seam. After passing the inspection, use a radial drill to drill the plug weld holes. The plug weld holes are processed by a drill press. S3. Assembling and welding the skeleton: First spot-weld the channel steel outer frame on the platform. Use a square to measure to ensure that the channel steel is at 90 degrees to the platform. Place the I-beam. The butt joint gap is ≤2 mm. Weld. After the skeleton is formed, the allowable deviation of the skeleton height is +2 mm. S4. Assemble and weld the panels to form the upper and lower door leaves. When assembling and welding the outer panel, first spot-weld the frame and the outer panel together, ensure the panel fits tightly against the frame, weld according to the weld requirements on the drawing, and transfer to the next process after passing the inspection; otherwise, rework. When assembling and welding the inner panel, weld the plug welds by spreading from the center to the periphery, and finally use a straight trolley welder to weld the four-sided welds, assemble and weld the embedded pressing plates, and polish the welds smoothly. When splicing the inner and outer panels, an automatic submerged arc welder must be used for welding, and the joint should be on the frame. During welding, ensure the welding wire is in the center of the weld bead. After the weld is formed, it should not be lower than the panel surface. S5. Splice the upper and lower door leaves. First, connect the two intermediate channel steels with bolts, then weld the channel steel and I-beam into a frame, and then weld the inner and outer panels. After the door leaves are assembled and welded, the inner and outer surfaces are flat, and the flatness tolerance and the perpendicularity tolerance of the adjacent sides are both 2 mm. The upper and lower door leaves and the door frame are assembled at the construction site with positioning pins and docking bolts. After assembly, ensure the mating surface is flat, and the flatness tolerance is 2 mm. S6. Weld the intermediate panel and shape it. The intermediate inner panel and the outer panel are welded on-site. After the door leaf is formed, there is deformation. Use the leveling device pre-installed on the intermediate panel and press it with a jack to make the panel fit tightly against the frame, and then weld in sections by area in sequence to make the flatness of the mating surface of the door leaf reach the standard allowable range.

7. The manufacturing method of the split-structured lightweight and high-strength civil air defense door with a leveling device according to claim 6, characterized in that, The allowable deviation range for cutting the inner and outer panels is as follows: when the panel width is ≥ 1000 mm and ≤ 2000 mm, the allowable deviation range is ±1 mm, and the skew angle ≤ 2 mm; when the panel width is > 2000 mm and ≤ 3500 mm, the allowable deviation range is ±2 mm, and the skew angle ≤ 3 mm.

8. The manufacturing method of the split-structured lightweight and high-strength civil air defense door with a leveling device according to claim 6, characterized in that The allowable deviation of the width of the door leaf panel frame is as follows: when the frame width is ≥ 1000 mm and ≤ 2000 mm, the allowable deviation range is +1 mm; when the frame width is > 2000 mm and ≤ 3500 mm, the allowable deviation range is +2 mm; when the frame width is > 3500 mm and ≤ 4500 mm, the allowable deviation range is +3 mm.

9. The manufacturing method of the split-structured lightweight and high-strength civil air defense door with a leveling device according to claim 6, characterized in that, The specific steps of step S3 include: S31. Mark the full-size pattern on the working platform according to the door leaf drawing, and then lay the I-beam and channel steel according to the full-size pattern respectively and make rigid fixation. S32. Cut the required round holes and square holes with a profiling cutting machine respectively, and perform secondary treatment on the cut edges to remove burrs and rust. S33. Use the production platform for positioning and assembly welding. Tighten all the weld seams. If the gap exceeds 1 mm, then perform fixed welding. At each joint, spot-weld 20 mm at both ends of the flange plate in the flat welding position, and spot-weld 30 - 40 mm in the middle of both sides of the web plate. S34. Weld the frame composed of channel steel and I-beam: When welding the frame, skip welding should be carried out from the middle to the periphery. The door leaf should be divided into 4 equal areas, and 4 welders should perform skip welding from the middle to the periphery of each area respectively. Press each component tightly against the positioning block on the platform, control the perpendicularity of the component to the positioning block not to be greater than 2 mm, and the flatness to be less than 1.5 mm. First, spot-weld. After checking that all dimensions are correct, weld in sequence from the inside to the outside according to the process standard to allow the welding internal stress to be released outward by itself. The welding sequence is as follows: First, weld the flat welds of the lower flanges of each grid area. After all are welded and cooled, then weld the fillet welds of the transverse I-beam webs and the lower flanges of the longitudinal I-beams. Finally, weld the butt flat welds of the upper flanges. When welding the inner panel to the skeleton, make them fit tightly, and carry out the welding in the sequence of intermittent welding and segmented welding. When welding the inner panel to the skeleton by plug welding, use a jack to press it firmly, and then carry out the welding in the sequence of segmented welding by area. First, position-weld a hole at an interval of 500 - 600 mm to connect the skeleton and the inner panel. To control the deformation of the door leaf, it is required that the joints of the panel must be opened with V-shaped grooves, welded on both sides, and the joints are on the I-beams. Press the outer panel tightly against the skeleton, with the gap not exceeding 1 mm. Carry out spot welding from the middle to the surrounding, with the interval not exceeding 400 mm, and the weld length is generally 30 - 50 mm. After spot welding is completed, then use staggered intermittent welds. First, weld the longitudinal I-beams and channels, and finally weld the transverse I-beams. Divide the inner panel into 4 areas, and 4 welders carry out skip welding at a distance of 800 - 1000 mm. Each welding hole is welded in three layers, and the temperature of each welding layer is controlled at 80 °C. After all the first layers of welding holes are welded, then weld the second layer, and after the second layer is welded, then weld the third layer. For the welding of the outer panel and the surrounding channels of the skeleton, divide the perimeter of the door leaf frame into multiple equal parts at intervals of 500 - 600 mm, and 4 welders carry out skip welding from the middle to both ends on the four seams. After all parts are adjusted, weld the outer panel. Carry out plug welding for the drilled holes on the outer panel, and finally carry out welding around. Since the outer dimension of the door leaf is relatively large, the joints of the panel are opened with V-shaped grooves. When welding on both sides, the welds must be on the I-beams. To reduce deformation, use the methods of simultaneous symmetric welding and segmented reverse welding. After the grid skeleton is welded, adjust the flatness, then lay the panel on the I-beam skeleton, and use a jack to hold it firmly. S35. The appearance quality of the welds is measured by a weld angle gauge, measure the weld thickness, weld reinforcement, and observe the cleaning conditions of weld slag inclusions, pores, and weld beads. The quality inspection personnel use a measuring instrument to check the dimensions and control the errors. Deal with the unqualified welding areas, and use an ultrasonic flaw detector to detect the weld quality. S36. Add reinforcing plates and connecting angle steels for fixation to reduce the degree of deformation. S37. Before welding the outer panel, spray two coats of anti-rust paint inside the skeleton, then assemble the locking mechanism components inside the door leaf, and carry out the planar debugging of the lock. Lubricate each rotating part.

10. The manufacturing method of the split-structured lightweight and high-strength civil air defense door with a leveling device according to claim 6, characterized in that The specific steps of step S4 are as follows: In the welding procedure of the outer panel and the skeleton: S41. Before welding, open the small protective door hole on the outer panel. Place the aligned and spliced outer panel flat on the platform, then lift and place the steel skeleton on it. Assemble it according to the dimensions required by the drawing and then carry out spot welding for positioning in the middle of the door leaf. S42. Position welding: After the door leaf is positioned, use the gantry steel and pressing codes to press the skeleton and the outer panel tightly, and check with a feeler gauge. The gap does not exceed 1 mm. Then carry out position welding from the middle to the surrounding at an interval of 350 - 400 mm, with a weld leg of 5 mm and a weld length of 30 - 50 mm. S43. After the tack welding is completed and all has cooled down, start skip welding from the middle longitudinal I-beam towards both ends. After all the longitudinal I-beams are welded, then weld the inner welds between the channel steel and the outer panel; the welding method is intermittent welding, with a weld fillet of 5 mm and a spacing of 50 mm, and the weld length is 50 mm. S44. After the fillet welds between the longitudinal I-beams, channel steel and the panel are completed, use the same method as in step S43 to weld the fillet welds between the transverse I-beams, channel steel and the outer panel. In the welding procedure of the inner panel and the framework: S441. Lay the inner panel with drilled plug weld holes, opened inspection holes and small protective door holes on the steel framework according to the specified dimensions. Spot weld 3 or 4 points in the middle of the panel to position the panel and the steel framework; then use a gantry to press from the middle to the periphery to press the inner panel and the steel framework tightly, with the gap not greater than 1 mm. S442. After the panel is pressed tightly, weld the plug weld holes in three layers; for the first layer, weld a pair of plug weld holes at intervals of 500 - 600 mm from the middle of the door leaf to the periphery, and fix the entire panel and the framework according to this distance; the first layer of plug welds should be evenly welded in a circle along the root of the plug weld hole, and the welding thickness shall not exceed 5 mm; for the remaining plug weld holes, after checking the deformation of the door leaf, adjust the welding sequence according to the actual situation of the door leaf. Before applying the first layer of welding, the panel and the steel plate framework must be pressed tightly. S443. After the first layer of plug welding of the panel is completed, divide the door leaf into four areas and perform skip welding from the middle of the door leaf to the periphery at intervals of 8000 - 1000 mm until all the second layers of plug weld holes are welded, and then weld the third layer. S444. Hammer to eliminate stress. Use a C6 type pneumatic chisel for hammering. Grind the chisel head into a spherical round head with R = 5 mm, and ensure that the working pressure of the air source is 0.63 MPa; hammering should be carried out immediately while the welds are still red-hot after each layer of welding is completed. S445. Welding of the inner and outer panels and the peripheral channel steel of the steel framework: Press the side seams tightly, divide the lengths of the four sides of the door leaf into equal parts of 500 - 600 mm; perform skip welding from the middle of the side length towards both ends until all are welded. S446. Welding of the middle rubber strip groove.

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