Large gantry crane girder zero-allowance construction control method

Abstract

A control method for zero-allowance construction of a main beam of a large gantry crane comprises the steps that the two ends of the main beam and sub-beams are divided to form two end beams and two sub-beams, then the two sub-beams are sequentially divided to form a plurality of segmented beams of any length, the distance between the edge of each segmented beam and an adjacent large partition plate needs to be 300 mm, welding compensation is added to an upper panel, a lower panel and a web of each segmented beam, and then the main beam and the sub-beams are welded. The method comprises the following steps: splicing a plurality of segmented beams to form sub-beams, splicing the sub-beams to form a main beam, carrying out a load test on the main beam, after the final load test is passed, keeping the crane no-load, and at the moment, measuring and recording a camber value and a profile of the main beam. And the turnover and construction time is shortened. The number of the segments is reduced, the construction continuity is improved, and the redundant procedures of manual cutting of the grinding amount and on-site beveling in the assembling stage of the small segments are abandoned.

Description

Technical Field

[0001] The invention belongs to the field of large-scale gantry crane beam design and construction, and in particular relates to a large-scale gantry crane main beam zero-residue construction control method. Background Art

[0002] At present, the main beam construction method of large gantry cranes generally reserves 50~100mm of welding grinding and matching amount for panels and webs on both sides of each section of the main beam. During construction, the grinding and matching amount is added to the left and right ends of the panels and webs of the main beam. The first is to prevent the shortening and distortion of the structure caused by welding shrinkage and welding deformation, and the second is to determine the length of each section before the overall assembly to control the overall length of the main beam in the next step. The construction sequence is: ⑴ Cutting the webs and panels of the main beam, adding grinding and matching amount to the left and right ends, and the panels and webs at both ends are not cut to meet the butt joints with the butt beams; ⑵ The panels and webs of the small sections of the main beam are welded to the horizontal and vertical stiffening ribs of its structure to prefabricate into a single beam; ⑶ After pressing the beam, the upper panel of the main beam is laid on the "concave" production frame, with the upper panel of the main beam as the bottom plate, and fixed, and then the reverse construction of the structure is carried out; ⑶ Mark the left and right sides of the panel, position the webs, and increase the web side Add supporting tooling to prevent the web from tipping over and forming lateral bending during welding; ⑷ Weld the internal profiles and other accessories of the main beam. At this time, the lower panel of the main beam has not yet been welded to the main beam; ⑸ Weld the lower panel of the main beam and weld the whole into a small section; ⑹ Then, according to the size requirements of the drawing, cut off the grinding and matching amount on both sides of the small section, and cut the butt groove at the interface between the panel and the web; ⑺ Repeat the construction from ⑴ to ⑹, and perform non-destructive testing on the welding grooves of each section; ⑻ Weld the main beam as a whole, cut off the excess grinding and matching amount, and perform non-destructive testing on the overall closing seam.

[0003] The above methods have the following main disadvantages: the welding process is complicated, the control of welding deformation is difficult, and compared with the crane involved in this patent, it is necessary to manually cut the 18 welds of a single main beam, and the workload of each cross section is nearly 70m². In addition, the construction personnel need to cut the groove on site at the assembly site, which increases the man-hours and the use of kinetic energy, which is not conducive to cost control and increases the construction cycle. Therefore, it is necessary to design a crane main beam construction method that can not only ensure the continuity of construction, improve the quality of welding, but also further reduce costs and improve work efficiency. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a large gantry crane main beam no-residue construction control method, aiming to improve manufacturing efficiency and effectively control welding deformation. The technical solution adopted is: A control method for the construction of a main beam of a large gantry crane without margins, a control method for the construction of a main beam of a large gantry crane without margins, characterized in that the main beam is composed of two sub-beams with the same structure, the cross section of the sub-beam is an isosceles trapezoid, and the sub-beam with a trapezoidal cross section is composed of two webs and an upper panel and a lower panel, a plurality of reinforcing ribs are fixed on the web, and the plurality of reinforcing ribs are continuously arranged along the length direction of the web, a plurality of large partitions are longitudinally inserted inside the sub-beam, and are perpendicular to the upper panel and the lower panel, the large partitions are composed of strip plates and support tubes, and four strip plates are enclosed to form an isosceles trapezoidal frame matching the cross section of the sub-beam, a plurality of support tubes are fixed in the frame, and the plurality of support tubes form a plurality of triangles reinforced in the frame from bottom to top; two sub-beams are arranged in parallel horizontally, there is a spacing between the two sub-beams, and the ends are welded into one by square end plates to form a main beam with a square cross section, and the overall length of the main beam is 129m; The specific construction method is as follows: S1: Split the two ends of the main beam and the sub-beam to form two end beams and two sub-beams, and then split the two sub-beams in sequence to form multiple segmented beams of any length. The edge of the segmented beam must be 300mm away from the adjacent large partition. Add welding compensation to the upper panel, lower panel and web of each segmented beam. The compensation value is 15mm. The segmented beam located in the middle of the sub-beam has compensation added on both sides, and the other segmented beams have compensation added on one side. By calculation formula: fa=main beam span*[0.9,1.4] / 1000; The prefabricated camber of the main beam = fa + the downward deflection of the main beam's deadweight + the correction value of the main beam's camber; The precast camber of the main beam is obtained, and the remaining camber values ​​are evenly distributed. The camber value at the projection of the main beam and the center span of the track is set to 0mm.

[0005] S2: Determine the web curve of each segmented beam according to the formula Y=fa*(122000-X)X / 61000², where Y is the main beam camber value at the calculation point; X is the distance from the calculation point to the starting point of the span. Add 1mm welding shrinkage to the web, upper panel and lower panel for every 1m in the length direction of the segmented beam, and strictly check the outer dimensions of the steel plate after cutting. The allowable deviation of the length dimension is ±2mm, the allowable deviation of the width dimension is ±1mm, the diagonal is <3mm, the allowable straightness of 3m in length is <3mm, the camber value is consistent with the actual line shape ≤2mm, and a K-type butt groove is opened on the edge of the web and panel.

[0006] S3: Use a spirit level to level the tire frame, place the web on the tire frame, and fix a metal pad on the lower surface of the thin part of the web according to the thickness data of the web in the drawing to ensure that the web is laid flat and solid and the assembly surface is horizontal. The main web is used as the bottom plate, the web that is first placed on the tire frame for welding is the main web, and the web that is welded later is the secondary web. Draw the center position line of the main web on the tire frame, and then draw the upper panel on the tire frame according to its inner width center line, web assembly center line, partition assembly center line, and partition width center line.

[0007] After drawing, assembly positioning welding is carried out, and the segmented beams are corner welded in the order of main web and large partition, upper panel and main web secondary web, secondary web and large partition, lower panel and main web secondary web; the web and upper and lower panels are welded by automatic welding, and welding materials with a diameter of 4.8mm are used for base, filling and covering. The welding current is 500~550A, the welding voltage is 28~32V, and the welding speed is 400~600mm / min for base welding; the welding current is 600~700A, the welding voltage is 32~36V, and the welding speed is 400~600mm / min for filling and covering, and the large partition, web and reinforcement are welded by gas shielded welding.

[0008] To prevent asymmetric deformation when welding fillet seams, the welding sequence is symmetrical from the middle to both sides.

[0009] S4: 24 hours after the completion of the splicing seam and fillet weld, UT flaw detection and dimension measurement shall be carried out on each segment beam and end beam. The quality of UT flaw detection shall not be lower than the Level 1 requirement in JB / T 10559. For suspicious parts, MT flaw detection is required, and the quality of MT flaw detection shall not be lower than the Level I requirement specified in JB / T 6061.

[0010] Use a total station to measure the diagonal of the cross section, diagonal of the longitudinal section, horizontal deflection of the upper and lower panels, horizontal height difference of the same section, distortion of the segmented beam, verticality of the web, waviness of the web, horizontal curvature of the beam, and length of the segmented beam, and compare the measured values ​​with the drawing data to see if there is too much deviation. If there is too much deviation, correct the size of the segmented beam to ensure that the measured value is within the allowable deviation range; the deviation of the diagonal of the cross section of the segmented beam shall not exceed 4mm, and the deviation of the diagonal of the longitudinal section of the segmented beam shall not exceed 5mm.

[0011] S5: Draw the ground sample reference line at the closing site, and place the pads and adjust the horizontal data values ​​starting from the mid-span segmental beam according to the position of each segmental beam on the closing ground sample. The horizontal data value adjustment is carried out with reference to the camber.

[0012] S6: When the segmented beams are butt-jointed, the segmented beam in the middle of the sub-beam is used as the reference, and the segmented beams are placed to both sides in sequence. After the two segments of the same cross-section are placed, they are adjusted and aligned according to the ground sample line. A level is used to detect the camber, vertical deflection of the web, horizontal deflection, horizontal bending and twisting of the upper panel, and the center distance and diagonal of the two adjacent segmented beams to meet the requirements of the ground sample line. After the above numerical tests are passed, the upper and lower panels of the two adjacent segments are sealed with tooling code plates, and the segmented beams are aligned with the center line of the ground sample, and the whole is assembled and welded to form a sub-beam.

[0013] S7: After the segmented beams are butt-jointed, all the closing positions of the segmented beams shall be inspected, and the welds shall be subjected to ultrasonic and radiographic inspections. The butt welds shall be ultrasonically inspected for 100% of their length, and their quality shall not be lower than the Level 1 standard of GB11345-B inspection. For important butt welds, 10% of the total length of the welds shall be sampled for radiographic inspection, and their quality shall not be lower than the Level II standard specified in GB / T3323. At least one film shall be taken for each tension weld.

[0014] S8: After the sub-beam size data is formed, measure the size of the sub-beam closing mouth, and then cut the upper and lower panels and webs of the end beam. The installation method of the end beam is the same as that of the sub-beam section. After the end beam is independently welded, the end beam is butt-jointed with the sub-beam. At this time, a K-shaped groove is made on the edge of the end beam, and a 2mm butt weld is reserved to complete the overall closing of the main beam and record the completed size.

[0015] S9: Carry out load test on the main beam. After the final load test, keep the crane unloaded. At this time, measure the camber value and profile of the main beam and record them.

[0016] The above-mentioned method for controlling the construction of a main beam of a large gantry crane without any excess, further, divides the sub-beams into sections according to the lifting capacity of the construction site, and the divided sectioned beams must be within the capacity range that can be lifted.

[0017] The above-mentioned large gantry crane main beam zero-residue construction control method further includes the main beam's web, upper panel and lower panel being cut using a plasma CNC cutting machine, and the cutting accuracy of the plasma cutting machine is <0.2mm.

[0018] The above-mentioned large gantry crane main beam zero-residue construction control method, further, in step S3, during positioning welding, gas shielded welding is used to first perform fillet welds on the main web and the large partition, and then the segmented beam is turned over 90° clockwise, and the upper panel is used as the bottom plate and placed on the tire frame, and then the upper panel of the segmented beam and the main web are welded by automatic welding. After the upper panel is welded to the main web, the segmented beam is turned over 90° clockwise, and the secondary web is used as the bottom plate and placed on the tire frame, and gas shielded welding is used to perform fillet welds on the secondary web and the large partition, and automatic welding is used to perform fillet welds on the secondary web and the lower panel, and the lower panel and the main web are welded.

[0019] The above-mentioned large gantry crane main beam zero-residue construction control method further comprises: in step S7, the tooling code plate is selected to have the same thickness as the main beam structure, and the basic thickness is 10, 14, and 20 mm.

[0020] The above-mentioned large gantry crane main beam zero-residue construction control method, further, the automatic welding adopts an automatic submerged arc welding wire trolley, model MZ-ZK-1000, the welding speed is 0.2~1.5m / min, and the wire feeding speed is 0.3~3m / min.

[0021] The above-mentioned large gantry crane main beam zero-residue construction control method, further, in step S6, the ground sample reference line includes: the trolley track center line, the main beam longitudinal center line, the trolley track center line, the main beam span center line, the end beam transverse center line, the end beam longitudinal center line and the segmented port line.

[0022] The beneficial effects of the present invention are: 1. Make the process more simplified. This method is based on the production capacity of the manufacturer and reasonably allocates the number of sections of the main beam, which can better carry out construction and transportation, reduce turnover and construction time. The number of sections is reduced, and the continuity of construction is also improved.

[0023] 2. The small segment closing increases the welding compensation amount, and the structural parts increase the welding shrinkage amount, thereby eliminating the redundant processes of manual cutting and matching and on-site beveling of small segments during the assembly stage.

[0024] 3. In the segmented group stage, the side panels are used as the base for construction, which can reduce the original standard value of the main beam lateral bending value of ≤20mm to ≤10mm, reducing the workload of correction after welding.

[0025] 4. It is more convenient to assemble small sections using a horizontal frame. The original main beam construction plan used the upper panel as the bottom plate for construction, which required welding a large number of partitions or piers at the bottom and building them into the shape of the main beam arch, which increased labor and consumed a large amount of welding materials and tooling materials.

[0026] 5. Reduced energy consumption and rework waste. The bevel of the closing seam has been cut in the cutting stage, which greatly reduces the uncontrollability of manual on-site beveling and improves the pass rate of flaw detection, thus eliminating a large amount of waste (labor costs, kinetic energy, materials, sites, lifting machinery, etc. for rework) and saving a lot of expenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the main beam structure rotated 90° from top to bottom and divided into sections; Figure 2 is a schematic diagram of the cross-sectional structure of the sub-beam; Figure 3 It is a schematic diagram of the segmented beam placed on the tire frame; Figure 4 It is a schematic diagram of the diagonal dimensions of the cross section of the main beam in the method of the present invention; Figure 5 It is a schematic diagram of the diagonal dimensions of the longitudinal section of the main beam in the method of the present invention; Among them, 1-web plate, 2-strip plate, 3-support tube, 4-tire frame, 5-upper panel, 6-lower panel. DETAILED DESCRIPTION

[0028] The present invention will be further described in conjunction with the accompanying drawings.

[0029] A 350t double-beam gantry crane, the main beam span design drawing requirements are 122m±25mm, the overall length of the main beam is 129m, such as Figure 1 As shown, the main beam is composed of two sub-beams with the same structure. The cross-section of the sub-beam is an isosceles trapezoid. The sub-beam with a trapezoidal cross-section is composed of a front web, a rear web, an upper panel, and a lower panel. A plurality of reinforcing ribs are fixed on the web, and the plurality of reinforcing ribs are continuously arranged along the length direction of the web.

[0030] like Figure 2 As shown, the large partition is composed of strip plates and support tubes. Four strip plates enclose an isosceles trapezoidal frame that matches the cross section of the sub-beam. Multiple support tubes are fixed in the frame. The multiple support tubes form multiple triangles and are reinforced in the frame from bottom to top. Multiple large partitions are inserted into the sub-beam at equal intervals, and the large partitions are arranged longitudinally inside the sub-beam. Two sub-beams are arranged side by side horizontally, with a gap between the two sub-beams. The ends are welded together through square end plates to form a main beam with a square cross section. The overall length of the main beam is 129m.

[0031] A method for controlling the construction of a main beam of a large gantry crane without excess is described in detail as follows: S1: splitting the two ends of the main beam from the sub-beam to form two end beams and two sub-beams, and then splitting the two sub-beams in sequence to form a plurality of segmented beams of arbitrary lengths, such as Figure 1As shown, each segmented beam is numbered. The edge of the segmented beam needs to be 300mm away from the adjacent large partition. Welding compensation is added to the upper panel, lower panel and web of each segmented beam. The compensation value is 15mm. The segmented beam located in the middle of the sub-beam has compensation added on both sides, and the remaining segmented beams have compensation added on one side.

[0032] By calculation formula: fa=main beam span*[0.9,1.4] / 1000.

[0033] The precast camber of the main beam = fa + the downward deflection of the main beam's own weight + the correction value of the main beam's camber.

[0034] Among them, according to the drawings, the span of the main beam is 122000mm, [0.9,1.4] takes the value of 1.4, so fa is 170mm, the main beam's self-weight deflection is 136mm, the main beam's arch correction value is 44mm, and the prefabricated upper arch of the main beam = 170mm+136mm+44mm.

[0035] The precast camber of the main beam is 350mm, and the remaining camber values ​​are evenly distributed, and the camber value at the projection of the main beam and the center span of the track is set to 0mm.

[0036] S2: Determine the web curve of each segmented beam according to the formula Y=fa*(122000-X)X / 61000², where Y is the main beam camber value at the calculation point; X is the distance from the calculation point to the starting point of the span. Add 1mm welding shrinkage to the web, upper panel and lower panel for every 1m length in the length direction of the segmented beam, and strictly check the outer dimensions of the steel plate after cutting. The length dimension allows a deviation of ±2mm, the width dimension allows a deviation of ±1mm, the diagonal is <3mm, the length of 3m allows a straightness of <3mm, the camber value matches the actual line shape ≤2mm, and the edges of the web and panel are opened with a K-type butt groove.

[0037] S3: Use a level to level the tire frame, and arrange strip metal pads (i.e. tooling plates of unequal thickness) on the platform at positions corresponding to the web assembly according to the unequal thickness dimensions of the webs in the drawings and weld them in place to ensure that the webs are laid flat and the assembly surface is level. Figure 3 As shown, the main web is used as the base plate, the web that is first placed on the tire frame for welding is the main web, and the web that is welded later in the process is the secondary web. The center position line of the main web is drawn on the tire frame, and then the upper panel is drawn on the tire frame one by one according to its inner width center line, web assembly center line, partition assembly center line, and partition width center line.

[0038] After drawing, assembly positioning welding is carried out. The segmented beams are corner welded in the order of main web and large partition, upper panel and main web secondary web, secondary web and large partition, lower panel and main web secondary web. Automatic welding is used to weld the web and upper and lower panels, and gas shielded welding is used to weld the large partition and web. The welding current, voltage, and temperature of the weld are controlled.

[0039] In order to prevent asymmetric deformation, the welding sequence in the above process is symmetrical welding from the middle to both sides.

[0040] S4: 24 hours after welding, each segment beam and end beam shall be inspected and dimensioned. like Figure 4 , 5 As shown, a total station is used to measure the diagonals D11 and D12 of the cross section of the segmented beam, the diagonals D21 and D22 of the longitudinal section of the segmented beam, the horizontal deflection of the upper and lower panels, the horizontal height difference of the same section, the distortion of the segmented beam, the verticality of the web, the waviness of the web, the horizontal curvature of the beam, and the length. The deviation of the diagonals D11 and D12 does not exceed 4 mm, and the deviation of the diagonals D21 and D22 does not exceed 5 m.

[0041] S5: Perform ultrasonic and radiographic testing on the welds. Perform ultrasonic testing on 100% of the butt weld length. The quality should not be lower than the Level 1 standard of GB11345-B inspection. For important butt welds, 10% of the total weld length must be sampled for radiographic inspection. The quality should not be lower than the Level II standard specified in GB / T3323. At least one film should be taken for each tensile weld.

[0042] S6: First, draw the ground sample benchmark, which includes: the center line of the trolley track, the longitudinal center line of the main beam, the center line of the trolley track, the center line of the main beam span, the transverse center line of the end beam, the longitudinal center line of the end beam, and the segmented port line. In order to ensure the quality of the panel, the horizontal tread and ground sample layout need to be checked, and the ground sample layout accuracy control is: ① Segmented ground sample dimension line accuracy: ≤1mm; ② Segmented ground sample diagonal difference: ≤1mm; ③ Closed ground sample dimension line accuracy: ≤1mm; ④ Closed ground sample diagonal accuracy: ≤2mm.

[0043] On the closed ground sample, according to the position of each segmented beam, start from the mid-span segmented beam to place the pads and adjust the horizontal data values. The adjustment of the horizontal data values ​​is carried out with reference to the camber.

[0044] S7: When the segmented beams are butt-jointed, the segmented beam in the middle of the sub-beam is used as the reference, and the segmented beams are placed to both sides in sequence. After the two segments of the same cross-section are placed, they are adjusted and aligned according to the ground sample line. A level is used to detect the camber, vertical deflection of the web, horizontal deflection, horizontal bending and twisting of the upper panel, and the center distance and diagonal of the two adjacent segmented beams to meet the requirements of the ground sample line. After the above numerical tests are passed, the upper and lower panels of the two adjacent segments are sealed with tooling code plates, and the segmented beams are aligned with the center line of the ground sample, and the whole is assembled and welded to form a sub-beam.

[0045] S8: After the sub-beam size data is formed, measure the size of the sub-beam closing mouth, and then cut the upper panel, lower panel and web of the end beam and cut the groove. The installation method of the end beam is the same as the installation method of the sub-beam section. After the end beam is installed, the end beam is connected to the sub-beam, and a K-shaped groove is made on the edge of the end beam, and a 2mm butt weld is reserved. The group erects the end beam, and finally completes the overall closing of the main beam, and records the completed size.

[0046] S9: Carry out load test on the main beam. After the final load test, keep the crane unloaded. At this time, measure the arch value and profile of the main beam and record them.

[0047] In order to ensure the welding quality of the panels, we abandon the uncertainty of manual welding quality and try to use automatic welding to improve the welding quality. We use the existing automatic submerged arc welding wire trolley (model MZ-ZK-1000), with a welding speed of 0.2~1.5m / min and a wire feeding speed of 0.3~3 m / min.

[0048] The tooling code plate uses the same thickness as the main beam structure, and the basic thickness is 10, 14, and 20 mm.

[0049] The material of the main beam steel plate and profile is: Q355C.

[0050] For the above steps: 1. Strictly ensure the levelness of the horizontal tread and the dimensional accuracy of each process; 2. When welding the panels automatically, code plates need to be installed at the starting and ending points of the automatic welding. The same automatic welding grooves should be opened at the joints between the code plates and the steel plates to enable full penetration welding and prevent welding defects. 3. During the hoisting operation, the main beam structure openings should be reinforced with steel pipes and channel steels that meet the structural strength to prevent the hoisting operation from damaging the structural dimensions; 4. Welding: Strictly follow the WPS welding process requirements and perform welding in the corresponding sequence.

[0051] Before welding, the weld needs to be preheated at a temperature of ≥10°C and monitored in real time using an industrial temperature measuring gun. This can be omitted if the ambient temperature permits. 5. NDT: UT and RT NDT shall be carried out as required.

[0052] The butt joints of important metal structural parts and T-joint welds with full penetration marked on the drawings shall be subjected to non-destructive testing after welding. The radiographic testing shall reach Level II in GB3323, and the ultrasonic testing shall reach Level B-I in GB11345. RT shall be no less than 10% of the total length, and UT shall be 100% full-length inspection. For the full penetration fillet welds, no less than 50% of the total length of the weld shall be extracted for ultrasonic testing, and its quality shall not be lower than the Level 2 standard of JB / T10559. For the suspicious parts, magnetic particle testing shall be performed again, and the defect level shall not be lower than the Level I standard specified in JB / T6061.

Claims

1. A control method for the construction of a large gantry crane main beam without excess, characterized in that: The main beam is composed of two sub-beams with the same structure. The cross section of the sub-beam is an isosceles trapezoid. It is composed of two webs and an upper panel and a lower panel to form a sub-beam with a trapezoidal cross section. Multiple stiffeners are fixed on the webs. The multiple stiffeners are continuously arranged along the length direction of the webs. Multiple large partitions are longitudinally inserted inside the sub-beams and are perpendicular to the upper panel and the lower panel. The large partitions are composed of strip plates and support tubes. Four strip plates are enclosed to form an isosceles trapezoidal frame that matches the cross section of the sub-beam. Multiple support tubes are fixed in the frame. The multiple support tubes form multiple triangles and are reinforced in the frame from bottom to top. The two sub-beams are arranged in parallel horizontally. There is a gap between the two sub-beams. The ends are welded together through square end plates to form a main beam with a square cross section. The overall length of the main beam is 129m. The specific construction method is as follows: S1: Split the two ends of the main beam and the sub-beam to form two end beams and two sub-beams, and then split the two sub-beams in sequence to form multiple segmented beams of any length. The edge of the segmented beam must be 300mm away from the adjacent large partition. Add welding compensation to the upper panel, lower panel and web of each segmented beam. The compensation value is 15mm. The segmented beam located in the middle of the sub-beam has compensation added on both sides, and the other segmented beams have compensation added on one side. By calculation formula: fa=main beam span*[0.9,1.4] / 1000; The prefabricated upper camber of the main beam = fa + the downward deflection of the main beam's deadweight + the correction value of the main beam's camber; Get the precast camber of the main beam, and evenly distribute the remaining camber values. The camber value at the projection of the main beam and the center span of the track is set to 0mm. S2: Determine the web curve of each segmented beam according to the formula Y=fa*(122000-X)X / 61000², where Y is the main beam camber value at the calculation point; X is the distance from the calculation point to the starting point of the span. Add 1mm welding shrinkage to the web, upper panel and lower panel for every 1m length in the length direction of the segmented beam, and strictly check the outer dimensions of the steel plate after cutting. The length dimension allows a deviation of ±2mm, the width dimension allows a deviation of ±1mm, the diagonal is <3mm, the length of 3m allows a straightness of <3mm, the camber value matches the actual line shape ≤2mm, and a K-type butt groove is opened on the edges of the web and panel; S3: Use a level to level the tire frame, place the web on the tire frame, and fix a metal pad on the lower surface of the thin part of the web according to the thickness data of the web in the drawing to ensure that the web is laid flat and solid and the assembly surface is horizontal. The main web is used as the bottom plate. The web that is first placed on the tire frame for welding is the main web, and the web that is welded later is the secondary web. Draw the center position line of the main web on the tire frame, and then draw the center line of the inner width of the upper panel, the center line of the web assembly, the center line of the partition assembly, and the center line of the partition width on the tire frame one by one; After drawing, assembly positioning welding is carried out, and the segmented beams are welded in the order of main web and large partition, upper panel and main web secondary web, secondary web and large partition, lower panel and main web secondary web; the web and upper and lower panels are welded by automatic welding, and welding materials with a diameter of 4.8mm are used for base, filling and covering. The welding current is 500~550A, the welding voltage is 28~32V, and the welding speed is 400~600mm / min for base welding; the welding current is 600~700A, the welding voltage is 32~36V, and the welding speed is 400~600mm / min for filling and covering. The large partition, web and reinforcement are welded by gas shielded welding; To prevent asymmetric deformation during fillet welding, the welding sequence is symmetrical welding from the middle to both sides; S4: 24 hours after the completion of the joint seam and fillet weld, UT flaw detection and dimension measurement shall be carried out on each segment beam and end beam. The quality of UT flaw detection shall not be lower than the level 1 requirement in JB / T 10559. For suspicious parts, MT flaw detection shall be carried out. The quality of MT flaw detection shall not be lower than the level I requirement specified in JB / T 6061. Use a total station to measure the diagonal of the cross section, the diagonal of the longitudinal section, the horizontal deflection of the upper and lower panels, the horizontal height difference of the same section, the distortion of the segmented beam, the verticality of the web, the waviness of the web, the horizontal curvature of the beam, and the length, and compare the measured values ​​with the drawing data to see if there is a large deviation. If there is a large deviation, the size of the segmented beam is corrected to ensure that the measured value is within the allowable deviation range; the deviation of the diagonal of the cross section of the segmented beam does not exceed 4mm, and the deviation of the diagonal of the longitudinal section of the segmented beam does not exceed 5mm; S5: Draw the ground sample reference line at the closing site, and place the pads and adjust the horizontal data values ​​starting from the mid-span segmental beam according to the position of each segmental beam on the closing ground sample. The horizontal data value adjustment is carried out with reference to the camber; S6: After the segmental beams are butt-jointed, all the closing positions of the segmental beams shall be inspected, and the welds shall be ultrasonically inspected and radiographically inspected. The butt welds shall be ultrasonically inspected for 100% of the weld length, and the quality shall not be lower than the Class 1 standard of GB11345-B inspection. Among the important butt welds, 10% of the total weld length shall be sampled for radiographic inspection, and the quality shall not be lower than the Class II standard specified in GB / T3323. At least one film shall be taken for each tensile weld; S7: When the segmented beams are butt-jointed, the segmented beam in the middle of the sub-beam is used as the reference, and the segmented beams are placed on both sides in sequence. After the two segments of the same cross section are placed, they are adjusted and aligned according to the ground sample line. A level is used to detect the camber, vertical deflection of the web, horizontal deflection, horizontal bending, distortion of the upper panel, and the center distance and diagonal of the two adjacent segmented beams to meet the ground sample line requirements. After the above numerical tests are qualified, the upper and lower panels of the two adjacent segments are sealed with tooling code plates, and the segmented beams are aligned with the center line of the ground sample, and the whole is assembled and welded to form a sub-beam; S8: After the sub-beam size data is formed, the size of the sub-beam closing mouth is measured, and then the upper panel, lower panel and web of the end beam are cut and grooved. The installation method of the end beam is the same as that of the segmented beam. After the end beam is independently welded, the end beam is butt-jointed with the sub-beam. At this time, a K-shaped groove is made on the edge of the end beam, and a 2mm butt weld is reserved to complete the overall closing of the main beam, and the completed size is recorded; S9: Carry out load test on the main beam. After the final load test, keep the crane unloaded. At this time, measure the arch value and profile of the main beam and record them.

2. A large gantry crane main beam zero-residue construction control method according to claim 1, characterized in that: The sub-beams are divided into sections according to the lifting capacity of the construction site, and the divided section beams must be within the lifting capacity.

3. A large gantry crane main beam zero-residue construction control method according to claim 1, characterized in that: The web, upper and lower panels of the main beam are cut using a plasma CNC cutting machine, and the cutting accuracy of the plasma cutting machine is <0.2mm.

4. A large gantry crane main beam zero-residue construction control method according to claim 1, characterized in that: In step S3, during positioning welding, gas shielded welding is used to first perform fillet welds on the main web and the large partition, then the segmented beam is turned over 90° clockwise, and the upper panel is used as the bottom plate and placed on the tire frame, and then automatic welding is used to perform fillet welds on the upper panel and the main web of the segmented beam. After the upper panel is welded to the main web, the segmented beam is turned over 90° clockwise, and the secondary web is used as the bottom plate and placed on the tire frame, and gas shielded welding is used to perform fillet welds on the secondary web and the large partition, and automatic welding is used to perform fillet welds on the secondary web and the lower panel, and on the lower panel and the main web.

5. The method for controlling the construction of a main beam of a large gantry crane without any margin according to claim 1, characterized in that: In step S7, the tooling code plate is selected to have the same thickness as the main beam structure, and the basic thickness is 10, 14, and 20 mm.

6. A large gantry crane main beam zero-residue construction control method according to claim 1, characterized in that: Automatic welding uses an automatic submerged arc welding wire trolley, model MZ-ZK-1000, with a welding speed of 0.2~1.5m / min and a wire feeding speed of 0.3~3m / min.

7. A large gantry crane main beam zero-residue construction control method according to claim 1, characterized in that: In step S6, the ground sample reference line includes: the trolley track center line, the main beam longitudinal center line, the trolley track center line, the main beam span center line, the end beam transverse center line, the end beam longitudinal center line and the segmented port line.

Images