A method for manufacturing a super-thick hollow pressure-bearing plate structure

Abstract

The application provides a manufacturing method of a super-thick hollow pressure-bearing plate structure, comprising the following steps: dividing the pressure-bearing plate into multiple splicing units and cutting; pre-deforming the butt joint welds between all the splicing units by the vector height distribution of the support tooth plate, and completing the overall assembly of all the splicing units at one time; after the front surface of all the butt joint welds is welded, the pressure-bearing plate is turned over for the first time and the back surface is welded; the welding process adopts CO2 gas protection backing welding and automatic filling and covering welding; the pre-welding preheating temperature is 100-200 DEG C; the backing welding current is 260+ / -20 A, the voltage is 28+ / -2 V, and the welding speed is 300+ / -30 mm / min; the filling and covering welding current is 680+ / -30 A, the voltage is 32+ / -2 V, and the welding speed is 400+ / -40 mm / min; the weld slope adopts a double-sided asymmetric U-shaped slope; the sum of the double-sided fusion depths of the pressure-bearing plate is not less than 2 / 3 of the plate thickness; and the front surface welding depth of the butt joint weld is at least 20 mm before turning over. The manufacturing process is first used without constraint, in a whole set and whole welding manner, and the construction efficiency is considered on the basis of deformation control, and the flatness precision can reach more than 1 mm / m.

Description

TECHNICAL FIELD

[0001] The present application relates to steel structure manufacturing, in particular to a manufacturing method of a special thick hollow pressure plate structure. BACKGROUND

[0002] At present, the special thick pressure plate structure applied on the large bridge steel tower in China is a solid web structure, which is made of special thick plates, and the welding deformation of the butt joint is mainly single and simple angular deformation. During the factory manufacturing, the total assembly after two splices, symmetrical arrangement of the weld, symmetrical welding, the use of heavy blocks or the forced constraint of welding deformation, and the restriction of the deformation trend by the weight of the steel plate, combined with the post-welding heat correction, can basically meet the expected flatness requirements.

[0003] The special thick hollow pressure plate structure mentioned in the present application is a bottom structure of a new type of steel-concrete composite tower, which is used on the transition part of the pressure plate block between the concrete and the steel structure tower, and bears a large load.

[0004] The special thick hollow pressure plate structure has the following manufacturing difficulties:

[0005] (1) It is difficult to guarantee the high flatness precision of 1mm / m

[0006] Firstly, the middle part of the pressure plate is hollow, the overall structure is not rigid enough, and the welds are mainly distributed on the side or corner. The butt joint of the special thick plate has a large welding filling amount, a large welding deformation, and a two-way angular deformation. Especially, the deformation trend of the plate at the corner of the component is more complex. If not properly controlled, it is easy to cause tens of millimeters of welding deformation, which is difficult to recover the flatness of the plate through heat correction later.

[0007] Secondly, the steel plates of the previous special thick pressure plate to be welded are basically symmetrical, the weight of the steel plate to be welded is symmetrical, the shape of the steel plate is symmetrical, the welding deformation is uniform and obvious, and it is easy to control. The special thick hollow pressure plate structure mentioned in the present application has an asymmetric structure, and the shape and weight of the steel plate to be welded are quite different. The center of gravity is asymmetrically distributed, the deformation trends of the two joints are different, and the welding deformation control is difficult. If the welding deformation is not properly controlled during the process, it is difficult to guarantee the precision requirement through heat correction later.

[0008] Thirdly, the traditional bulk process, i.e. the method of completing the correction of small assemblies after two-by-two splicing, and finally completing the total assembly, has the problem of large cumulative assembly accuracy error.

[0009] (2) The traditional bulk process also has the problem of low efficiency. Under the condition of considering symmetrical welding of the weld, the turning over times of the pressure plate during the manufacturing process are as high as dozens of times.

[0010] The above difficulties have no mature cases to refer to in similar structural members in the prior art, and serious deformation caused by improper operation method will directly lead to the scrapping of the structural member if there is no proper method for correction and repair. SUMMARY

[0011] The present application aims to provide a manufacturing method for a special thick hollow pressure plate structure with high manufacturing efficiency and guaranteed accuracy.

[0012] Technical scheme: The present application provides a manufacturing method for a special thick hollow pressure plate structure, comprising: dividing the pressure plate into multiple splicing units and cutting; setting pre-deformation for the butt welds between all splicing units through the distribution of the support tooth plate height, and completing the overall assembly of all splicing units at one time, after the front surface of all butt welds is welded, the back surface is welded after the first overturning.

[0013] The present application uses a non-constrained, whole assembly and whole welding manufacturing process for the first time, and after one-time single-sided welding of all butt welds, the other side is welded after overturning, the overturning frequency is low (reducing 90% of the overturning workload in the splicing and welding process of the special thick plate), the manufacturing efficiency is high (more than 50% higher than the traditional two-splicing and overall assembly process), the safety hidden danger is small (avoiding the safety hidden danger caused by multiple overturning), and the cumulative accuracy error caused by multiple assembly in the traditional two-splicing and overall assembly process can be avoided; during the splicing and welding process, each splicing unit is in a free shrinkage deformation state, that is, no weight block or mar plate is used for welding seam forced constraint, which can effectively reduce the welding residual stress in the structure; since the pre-deformation is set before welding, the pressure plate is basically flat after welding, and the local uneven part is corrected by flame, and the post-welding heat correction workload is reduced by more than 80% compared with the traditional process, and the influence of flame correction and even overcorrection on the mechanical properties of the base material can be avoided, and the flatness after correction can reach 1mm / m accuracy requirement.

[0014] Further, the division of the pressure plate into multiple splicing units follows the principle of as few butt welds as possible and as small area of corner-shaped plate parts as possible, wherein the control of as few butt welds as possible can reduce welding deformation, and the control of as small area of corner-shaped plate parts as possible can save material.

[0015] Further, when cutting, in order to facilitate cutting and avoid cutting defects at the cutting ignition point, and to avoid the cutting of thick plates caused by the traditional preheating cutting method, a blank part is drilled at the edge of the material before cutting, the hole diameter is 20-40mm, and the local correction of the flatness of the steel plate near the cutting edge is performed after the cutting is completed.

[0016] Further, due to the different self-weight of the to-be-welded head steel plate and the asymmetric distribution of the gravity center, the deformation sizes of the two to-be-welded joints are different, different pre-deformation amounts need to be set for different butt welds, and the height difference of the support tooth plate for setting pre-deformation is between 0-40mm.

[0017] Further, to ensure the stability of the welding quality of the thick plate weld and to reduce the influence of the first backing welding on the angular deformation of the joint, the welding process adopts CO2 gas protection backing welding and automatic filling and covering welding; the preheating temperature before welding is 100-200 DEG C; the backing welding current is 260+20A, the voltage is 28+2V, and the welding speed is 300+30mm / min; the filling and covering welding current is 680+30A, the voltage is 32+2V, and the welding speed is 400+40mm / min.

[0018] Further, the sum of the double-sided fusion depths of the pressure plate is not less than 2 / 3 of the plate thickness; considering that the butt weld is in a shearing state during the overturning, to avoid the shearing of the weld causing excessive angular deformation or even weld failure, before the first overturning, all the butt welds need to be welded at least 20mm deep on one side to ensure that the weld stress meets the requirements during the overturning.

[0019] Further, because the welding filling amount is too large due to the above-mentioned welding at least 20mm deep on one side, it is difficult to offset the deformation generated after the overturning, therefore, the weld groove form is designed as a double-sided asymmetric U-shaped groove, the deep groove side is 48mm deep, the shallow groove side is 40mm deep, the groove angle is 20 DEG, and the groove bottom is R10mm arc.

[0020] Further, during welding, the front side is welded to a thickness of 20-25mm, the first overturning is performed, and then the back side is welded to a thickness of 30-35mm; after the flatness of the steel plate is measured to meet the requirements, the second overturning is performed, the front side is welded to the end of the covering, and the third overturning is performed, the back side is welded to the end of the covering.

[0021] Further, the welding sequence is: first, welding the butt welds of the spliced units which provide rigid support to the overall structure, then, welding the transverse butt welds of the outer contour corner, and finally, welding the remaining longitudinal butt welds; the same type of symmetrically distributed welds are welded simultaneously and in the same direction. The technical solution further reduces the welding deformation by the rigidity of the structure itself, and the same type of symmetrically distributed welds welded simultaneously and in the same direction can evenly disperse the deformation.

[0022] Further, during the overturning of the pressure plate, the most stable direction is selected to prevent the elastic-plastic deformation from expanding the welding deformation.

[0023] The present application controls the welding deformation by formulating welding deformation control measures in aspects such as block division of the pressure plate, pre-deformation setting, welding filling amount, welding process parameters, and welding sequence, so that the welding deformation of the overall manufacturing of the thick hollow pressure plate structure is controllable (the welding deformation of the special-shaped asymmetric welding joint is controllable), and the flatness precision of the overall manufacturing of the thick hollow pressure plate structure can reach more than 1mm / m.

[0024] Beneficial effects: compared with the prior art, the present application has the following remarkable advantages: adopting a non-restricted, integrated and integrated welding manufacturing process, having the advantages of high precision, high efficiency, high safety, etc. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is an embodiment, a special thick hollow pressure plate structure assembly schematic diagram;

[0026] Figure 2 is a U-shaped groove structure schematic diagram;

[0027] Figure 3 is a J-shaped groove structure schematic diagram;

[0028] Figure 4 is an embodiment, a support tooth plate arrangement and a pre-deformation amount setting schematic diagram before welding;

[0029] Figure 5 is an embodiment, a special thick hollow pressure plate structure welding sequence schematic diagram;

[0030] Figure 6 is an embodiment, a lug arrangement position schematic diagram;

[0031] The drawings show that: 1 is an angle block, 2 is a side block, and 3 is a vertical rib. DETAILED DESCRIPTION

[0032] The present application will be further described in detail below in combination with the drawings.

[0033] This embodiment takes a hollow pressure plate structure with length x width x thickness of 15790mm x 15790mm x 120mm as an example to specifically introduce a manufacturing method of a special thick hollow pressure plate structure, including the following steps:

[0034] I. Determine the pressure plate block scheme

[0035] According to market research, the maximum plate length of a 120mm thick steel plate supplied by a steel plant is 14m. In order to control the number of butt welds, reduce the overall profile size of special-shaped components, and avoid material waste, the pressure plate is divided into 12 splicing units, including 4 angle blocks 1, 4 side blocks 2 and 4 vertical ribs 3, as shown in Figure 1 The total number of butt welds is 14, including 10 longitudinal butt welds and 4 transverse butt welds.

[0036] II. Pressure plate blanking

[0037] In order to facilitate cutting, avoid cutting defects at the cutting fire point, and at the same time avoid the thick plate cutting caused by the traditional preheating cutting method, first drill holes with a diameter of 30mm at the blanking edge of the blanking thick plate. After blanking, the flatness of the steel plate near the cutting edge is locally corrected.

[0038] III. Design of pressure plate groove

[0039] The pressure plate needs to meet the welding requirement that the sum of the double-sided penetration is not less than 2 / 3 of the plate thickness. Considering that the butt weld is in a shearing state during the overturning, in order to avoid the weld shearing leading to excessive deformation of the block angle or even weld failure, theoretical calculation shows that at least 20mm single-sided welding is required for all butt welds to ensure that the weld stress meets the requirements during the overturning. At this time, due to the excessive welding filling amount, it is difficult to offset the deformation after the back welding after the overturning. Therefore, the weld groove form is designed as a double-sided asymmetric U-shaped groove. In this embodiment, the butt weld between the vertical rib 3 and the side block 2 is designed as an asymmetric J-shaped groove, which reduces the groove machining process of the side block 2 and prevents the groove misplacement of the welding joint caused by the groove position error of the side block 2. As shown in Figure 2 and Figure 3 The included angle of the asymmetric U-shaped groove is 20°, the groove depth of the deep groove side is 48mm, the groove depth of the shallow groove side is 40mm, the groove bottom is R10mm arc, and the bevel is 32mm. The included angle of the symmetric J-shaped groove is 30°, the groove depth of the deep groove side is 48mm, the groove depth of the shallow groove side is 40mm, the groove bottom is R10mm arc, and the bevel is 32mm. Compared with the general V-shaped groove, the U-shaped groove and the J-shaped groove reduce the welding deposition metal filling amount, which greatly reduces the welding deformation.

[0040] IV. Development of welding process and parameters

[0041] The butt weld of the pressure plate requires groove welding and needs to meet the GB / T11345-2013 II level weld quality requirement.

[0042] According to the above requirements, the gas shielded welding + automatic submerged arc welding process is preferred in terms of welding method; in terms of material performance, according to the material characteristics and use requirements of the pressure plate Q420qD, the matching welding material is selected, that is, the backing welding material is solid wire G55A4UC1ZSN2Φ1.2, and the filling and covering welding material is S49A4UFB-SUG35H5Φ5.0 submerged arc welding wire-solder combination.

[0043] According to the proposed welding groove form, welding method, welding material and welding process parameters, the corresponding welding process evaluation test is carried out according to the standard specification requirements, and the evaluation result reaches the expected weld quality target, the weld quality is stable, and it is feasible for construction.

[0044] The welding process parameters in the following table are executed during the site welding.

[0045]

[0046] V. Development of welding deformation control measures

[0047] A series of welding deformation pre-control measures are taken before and during the welding of the pressure plate to reduce the amount of welding deformation of the pressure plate and ensure that the product quality meets the expected flatness requirements. The following measures are taken.

[0048] (1) Pre-welding deformation setting

[0049] To avoid excessive deformation during front welding, especially to strictly control the welding deformation of the corner part, pre-welding deformation setting is completed on the ground platform by pre-fabricating support tooth plates. The specific deformation amount is set by the distribution of the height of the support tooth plates. Due to the asymmetric butt joint steel plate of the hollow pressure plate structure, the weight of the to-be-welded joint steel plate is different and the center of gravity is asymmetrically distributed, the deformation of the two to-be-welded joints is different, and different butt welds need to be set with different pre-deformation amounts. The height difference of the support tooth plates for setting pre-deformation is between 0-40mm. In this embodiment, the support tooth plate has a thickness of 30mm, a width of 300mm, and a height of 60-100mm.

[0050] According to the structural characteristics of this embodiment, the reverse deformation amount design value is set larger due to the small weight of the corner component and the existence of two-way angular deformation; the reverse deformation amount of the remaining components is set smaller. Through welding seam arrangement analysis, the entire structure shows an upward deformation trend on the outer ring structure after welding. The specific support tooth plate support arrangement and reverse deformation amount design value are shown in the attached Figure 4 , the numbers in the box are the elevations of the support tooth plates, with units of mm.

[0051] (2) Develop overall welding sequence

[0052] In this embodiment, under the premise of ensuring welding deformation control, the hollow thick plate structure is considered for overall assembly and welding, that is, all 12 hollow thick plate splicing units are assembled and positioned, and after one-time single-sided welding of 14 welds, the other side is flipped, which reduces the number of flips and avoids the cumulative accuracy error of multiple joint assembly.

[0053] As shown in Figure 5 , to reduce welding deformation, combined with the structural characteristics of the component, the support and restraint of the two vertical ribs on the entire hollow thick plate are utilized, and the 14 welds are welded in the following order: first, the lengthening welds between the two vertical ribs in the structure (serial number ①), then the four horizontal butt welds of the outer contour corner butt joint (serial number ②), and finally the remaining eight longitudinal butt welds (serial number ③). As can be seen, due to the support of the two vertical ribs on the hollow pressure plate structure in the horizontal direction, the eight longitudinal butt welds, which are the last to be welded and have a large number, can be sufficiently constrained in terms of horizontal angular deformation. In addition, the same type of symmetrically distributed welds should be welded simultaneously in the same direction to evenly distribute the deformation, and all the welding directions are towards the outer ring of the overall structure.

[0054] (3) Strictly implement the welding process specification

[0055] According to the welding process parameters determined by the welding process evaluation, strictly control the welding preheating temperature and the temperature between each weld; strictly control the vehicle speed to ensure uniform welding speed; control the current and voltage, and try to use the lower limit for welding; after welding, use slow cooling or heat preservation measures to protect the weld. Through constant process parameter control, the weld stress is uniform, and local large deformation is not caused.

[0056] (4) Symmetrical welding to control welding deformation

[0057] After completing the assembly and positioning of all spliced units on the pre-deformation bench, weld the front surface with a thickness of 20-25 mm, which can ensure the safety of lifting and turning, then weld the back surface with a thickness of 30-35 mm, and measure the flatness of the steel plate. When the flatness is basically flat, perform the second turning, weld the front surface to the cover surface, and then perform the third turning, weld the back surface to the cover surface. After welding, use slow cooling or heat preservation measures to protect the weld.

[0058] If the welding deformation exceeds the predetermined deformation during welding, and the weld filling thickness does not meet the above requirements, in order to control the welding deformation from expanding, the number of turning welding can be increased to achieve the goal of minimizing welding deformation.

[0059] (5) Develop a turning plan

[0060] Although the pressure plate is thick, its outline size is large, and the middle part is hollow, the overall rigidity and flat bending resistance of the structural member are insufficient, and a special plan needs to be developed for welding and turning. Considering the size and weight of the pressure plate, a large gantry crane, lifting rigging and welding lifting lugs are used for turning, and stress analysis is performed to ensure the safety of the construction operation.

[0061] Turning direction: The turning direction should consider the welding deformation direction, dead weight, lifting deformation, etc. The direction with the most stable rigidity of the structural member is selected to prevent the occurrence of elastic-plastic deformation and expansion of the welding deformation, while ensuring the safety of turning, i.e. adopting horizontal lifting to perform in-air posture turning, effectively utilizing the vertical ribs to provide rigid support to the overall structure.

[0062] Turning timing: The turning should be performed after welding a suitable thickness of weld on the first surface. The weld thickness should be the minimum thickness that can ensure the safety of the component stress during turning, and should not be too thick, otherwise the angular deformation will be too large and the subsequent welding will not be able to effectively restore the flatness of the plate.

[0063] The lug plate for turning is 40 mm thick, and a total of 4 lug plates are provided, which are welded with the pressure plate block according to double-sided equal strength bevel groove welds. After welding, ultrasonic non-destructive testing is performed, and the turning operation is performed after passing the test. The lug arrangement drawing is shown in Figure 6 .

[0064] Six, local uneven parts are modified by hot correction measures

[0065] The overall flatness of the pressure plate is detected by using the feature point and the pull line method. Since the pre-deformation is set before welding, the pressure plate is basically flat after welding. The local uneven parts are corrected by flame correction, and the flatness after correction can reach the accuracy level of 1 mm / m or above.

Claims

1. A method for manufacturing a super-thick hollow pressure-bearing plate structure, characterized in that, The manufacturing process is non-restricted, integral and integral welding, including: dividing the pressure plate into multiple splicing units and cutting; pre-deforming the butt welds between all splicing units by the height distribution of the support tooth plate, setting different pre-deformation amounts for different butt welds, and completing the overall assembly of all splicing units at one time; after completing the front welding of all butt welds, performing the first overturning and welding the back; The sum of the double-sided fusion depth of the pressure plate is not less than 2 / 3 of the plate thickness; before the first overturning, the front welding depth of the butt weld is at least 20 mm; during welding, the front welding thickness is 20-25 mm, after the first overturning, the back welding thickness is 30-35 mm; after the planeness of the steel plate is measured to meet the requirements, the second overturning is performed, the front welding is performed to the finish, the third overturning is performed, the back welding is performed to the finish; the pressure plate is overturned by using a large gantry crane, a lifting sling and a welding lifting lug; when the pressure plate is overturned, the most stable direction in rigidity is selected; The welding sequence is: first, welding the butt welds of the splicing units which provide rigid support to the overall structure, then welding the horizontal butt welds of the outer contour corner, and finally welding the remaining longitudinal butt welds; welds of the same type and symmetrical distribution are welded simultaneously and in the same direction.

2. The production method according to claim 1, characterized by, The division of the pressure plate into multiple splicing units follows the principle of minimizing the number of butt welds and minimizing the area of the corner-shaped plate members.

3. The method of making of claim 1, wherein, When cutting, first drill holes in the blanking edge of the thick plate to be cut, and then perform local correction on the planeness of the steel plate near the cutting edge after cutting is completed.

4. The method of making of claim 1, wherein, The height difference of the support tooth plate is 0-40 mm.

5. The method of making of claim 1, wherein, The welding process adopts CO2 gas protection backing welding and automatic filling cover welding; the preheating temperature before welding is 100-200℃; the backing welding current is 260±20A, the voltage is 28±2V, and the welding speed is 300±30mm / min; the filling cover welding current is 680±30A, the voltage is 32±2V, and the welding speed is 400±40mm / min.

6. The method of making of claim 1, wherein, The welding groove form adopts a double-sided asymmetric U-shaped groove, the deep groove side is 48 mm, the shallow groove side is 40 mm, the groove angle is 20°, and the groove bottom is R10mm arc.

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