Forge welding forming process for main cable saddle of suspension bridge

Abstract

The invention relates to application of forging and welding technologies in manufacturing and forming of a cable saddle of a suspension bridge, and particularly discloses a forging and welding forming process of a main cable saddle of the suspension bridge, which mainly comprises the following steps of: (1) forming a base plate and a bottom plate of a cable saddle groove by adopting a forging process, and (2) blanking to form each component of a saddle body structure and a side wall plate of the cable saddle groove; (3) the cable saddle groove bottom plate and the side wall plate are welded to obtain the cable saddle groove; and (4) the plate welding sequence of the saddle body structure is planned to obtain the optimal welding space and welding quality. In the traditional process, the cable saddle groove is generally formed by casting, so that the quality strength of the cable saddle groove is low, and the cable saddle groove bottom plate in the scheme is formed by forging, so that the purposes of light weight and strength improvement are achieved.

Description

Technical Field

[0001] The invention relates to the application of forging and welding technology in the manufacturing and forming of a suspension bridge saddle, and in particular to a forging and welding forming process of a main saddle of a suspension bridge. Background Art

[0002] my country's bridge design and construction capabilities are developing rapidly. Among the top ten completed and under-construction suspension bridge projects in the world, my country accounts for 8. The saddle is an important load-bearing component of the suspension bridge. The larger the span of the saddle body, the heavier the weight of the saddle body. Generally, there are 4 sets of main saddles and 4 sets of loose saddles in the whole bridge. In the large-span suspension bridge, the traditional cast saddle is used. The weight of the main saddle is basically at the level of 200 tons, and the maximum lifting weight of a single piece reaches 150 tons. This is a huge challenge for the transportation and installation of the saddle, especially in mountainous areas. This problem is more obvious.

[0003] Castings have a wide range of applications and are not limited by the size, thickness, and complexity of shapes of castings, and their production methods are flexible. At present, cable saddles mainly adopt a fully cast or cast-welded structure design. The cast-welded combination is that the saddle head used for limiting and directly bearing the main cable is formed by a casting process, while the saddle head and the saddle body are combined by a welding process. However, the casting industry consumes a lot of energy and causes great pollution; therefore, casting companies with small scale, backward technology, serious pollution, and poor working conditions have been eliminated in recent years, resulting in a shortage of casting resources and a significant extension of the casting period of cast steel year-on-year; this has in turn lengthened the manufacturing cycle of cable saddles, increased capital investment, and increased the manufacturing cost of cable saddles.

[0004] In addition, steel castings have the characteristics of uneven organization, coarse internal grains and non-dense organization, which leads to low mechanical properties. As the span of bridges increases, oversized cable saddle structures are common. The tensile strength grade of the main cable wire has increased from 1670MPa to more than 2000MPa. As the strength of the main cable increases, the pressure on the saddle groove per unit cross section increases, and the contact stress at the bottom of the groove increases. Through the sliding test of cast steel cable saddles and high-strength steel wire strands, it was found that after the strands slipped, very obvious and dense main cable wire tensile indentations were formed on the side walls of the saddle groove and the bottom of the strand groove. The indentation depth was mostly between 0.5 and 1mm, and there were even cases where the indentation depth exceeded 1mm. Therefore, the molding quality and mechanical properties of the oversized casting saddle head face real challenges, and even the strength of its material is no longer compatible with the high-strength main cable wire.

[0005] Influenced by casting conditions, quality and the demand for lightweight cable saddles, the industry has proposed a new idea of ​​using forging technology instead of casting technology. Since the materials manufactured by forging technology have high strength, good mechanical properties and compact internal structure, using forging technology instead of casting technology can reduce the amount of materials used and achieve the purpose of improving the quality and lightweight of cable saddles. However, due to the conditions of the forging process, the entire cable saddle cannot be obtained directly by forging, so the cable saddle structure must be decomposed and then welded as a whole by welding technology, that is, when the cable saddle is manufactured by forging technology, a forging and welding combined structural design must be adopted. Since the forging and welding combined cable saddle structure uses high-strength materials, the requirements for welding strength are also extremely high; and the forging and welding combined cable saddle structure has many components. If the welding process and welding sequence are not planned, it will lead to problems such as narrow welding space, insufficient welding strength, and weld cracks caused by welding stress concentration, thus failing to form a qualified product. Summary of the invention

[0006] The present invention provides a forging and welding forming process for a main cable saddle of a suspension bridge, so as to improve the strength of the main cable saddle and realize the lightweight of the main cable saddle, and reduce the welding difficulty by reasonably planning the welding process, so as to ensure the product quality.

[0007] To solve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: the main cable saddle is composed of a seat plate, a cable saddle groove and a saddle body structure welded by high-strength steel plates, and the cable saddle groove is composed of a bottom plate and a side wall plate blanked by high-strength steel plates; the main cable saddle adopts a two-section or three-section design structure and is connected into a whole by high-strength bolts. The forging and welding forming process of the main cable saddle includes the following steps: Step 1: Forming the bottom plate of the saddle groove by forging process; Step 2: Cut the components of the saddle body structure and the side wall panels of the saddle groove; Step 3: Weld the bottom plate of the saddle groove to the side wall plate to obtain the saddle groove; Step 4: Two main rib plates and multiple middle partition plates are joined on the seat plate surface by positioning welding. The two main rib plates are arranged relatively parallel, and the middle partition plates are distributed between the two main rib plates along the length direction of the main rib plates to form a grid structure, thus completing the welding of the seat plate and the saddle body structure; Step 5: Position the saddle groove on the saddle body structure, and use single-sided welds between the main rib plate of the saddle body structure and the middle partition plates at both ends and the bottom surface of the saddle groove to complete the combined welding of the saddle groove and the saddle body structure; Step 6: Position side rib plates perpendicular to the main rib plates between the side wall plates and the seat plates on both sides of the saddle groove, and weld the butt joints between the side rib plates and the main rib plates, the seat plates, the saddle groove bottom plates, and the saddle groove side wall plates; Step 7: Weld the vertical rib plates between the adjacent side rib plates on both sides of the saddle body structure.

[0008] The beneficial effects of this solution are: 1. The saddle groove of the main saddle is in direct contact with the cable, and the bottom plate of the saddle groove directly bears the pressure transmitted by the cable. The bottom plate of the saddle groove has the highest requirements for strength and toughness. Traditional saddle grooves are generally cast. In order for the saddle groove to bear the pressure transmitted by the cable, the saddle groove usually increases the material consumption to ensure the reliability of strength. In this solution, the bottom plate of the saddle groove is forged, which can ensure the reliability of strength while reducing the material consumption. The side wall plate of the saddle groove is not the main load-bearing part, and it is made of high-strength steel plate like the frame structure, which fully reflects the design principle of "using good steel on the blade". At the same time, the seat plate and the side wall plate of the saddle groove are made of high-strength steel plate, which can simplify the process and reduce the processing cost.

[0009] 2. In the traditional main cable saddle structure, its structure is usually divided into two parts: the saddle head and the saddle seat. That is, in the traditional cast-welded main cable saddle structure, the saddle head is formed by casting, and the saddle seat is welded from steel plates. After the saddle head and the saddle seat are processed, the saddle head and the saddle seat are connected as a whole by welding or bolting, which is conducive to improving the processing efficiency. When the saddle head and the saddle seat are connected by welding, the side rib plate connecting the saddle head and the saddle seat usually plays a role in transmitting force. In the present scheme, the main rib plate, the middle partition plate and the side rib plate play the role of transmitting force from the cable saddle groove to the saddle body structure; if the traditional method disclosed in the patent with announcement number CN106181090 B is adopted: based on the saddle head, the main rib plate and the middle partition plate are first welded on the saddle head bottom plate so that the main rib plate and the middle partition plate can be fully welded, the welding quality requirements of the main rib plate, the middle partition plate and the cable saddle groove are high, and 3 to 5 layers of weld layers need to be repeatedly applied. In the present scheme, the weld length of the side rib plate is long, and the lateral force transmitted from the cable saddle groove to the side rib plate can be better dispersed to the weld of the side rib plate, thereby playing a major load-bearing role, thereby appropriately reducing the welding requirements of the main rib plate, the middle partition plate and the cable saddle groove. Therefore, the present scheme first welds the core part of the middle part of the saddle body based on the bottom plate, which can improve the welding efficiency.

[0010] 3. This solution first welds the main rib plate and the middle partition plate into a grid-shaped positioning weld on the seat plate, which is more conducive to the positioning of the saddle body structure, and then welds the saddle groove to the top of the saddle body structure. After completing the welding of the grid structure formed by the seat plate, the main rib plate and the middle partition plate and the saddle groove, the side rib plate is welded, which is conducive to the adjustment and correction of the side rib plate. If the traditional method disclosed in the patent with announcement number CN111218892 B is adopted: the saddle body is first completely welded into shape, and the welds between the saddle groove and the side rib plate are concentrated on the bottom surface of the saddle groove, and the upper part of the saddle groove is a cantilever structure. Since the side rib plate cannot be completely spot welded and positioned in the height direction, the heat generated during the welding process can easily cause thermal deformation of the side rib plate. When the saddle groove is placed into the saddle body structure, the saddle groove cannot be correctly positioned. And if Figure 1As shown, the side rib plate at the section is formed by two identical side rib plates being fixed together to form a complete side rib plate. In this scheme, the saddle groove is a three-section structure. If a single-section saddle groove is welded to the side rib plate at the bottom and then multiple sections of the saddle groove are spliced, the side rib plate at the section is easily misplaced when the saddle groove falls into it. The welding method of this scheme is to first complete the welding of the grid structure formed by the bottom plate, the main rib plate, and the middle partition plate to the saddle groove, and then weld the side rib plate, which can reduce the welding deformation of the side rib plate.

[0011] Preferred solution 1: As a further optimization of the basic solution, the vertical rib plate includes a first vertical rib plate and a second vertical rib plate. The bottom edge of the first vertical rib plate is welded to the top surface of the seat plate, and the side walls of the first vertical rib plate are respectively welded between the middle parts of the opposite surfaces of adjacent side rib plates; the bottom edge of the second vertical rib plate is welded to the top surface of the seat plate, and the plane where the second vertical rib plate is located is flush with the side edges of the adjacent side rib plates.

[0012] Two rows of vertical rib plates are welded between adjacent side rib plates. On the one hand, this increases the support between the side rib plates to ensure structural stability. On the other hand, it increases the support area between the side rib plates and the bottom plate so that the stress can be dispersed on the seat plate.

[0013] Optimal Option 2: As a further optimization of Optimal Option 1, during welding, after the positioning welding of the components is completed, the welding groove and surrounding areas are preheated with a natural gas flame. The preheating temperature of the high-strength steel plate butt joint should be controlled at 100-150°C, and the preheating temperature of the forging should be controlled at 250~300°C.

[0014] The welding of thick plates and extra-thick plates has problems such as large welding residual stress, large deformation after welding, and easy generation of hot cracks and cold cracks. The purpose of preheating is to slow down the temperature gradient and cooling rate when the weld joint is heated, reduce or avoid the generation of hardened structure, reduce welding stress and deformation, facilitate the escape of hydrogen, and prevent the generation of cracks.

[0015] Optimal Option 3: As a further optimization of Optimal Option 2, after the welding of the welds on the bottom plate and the bottom block of the saddle groove is completed, the welds and the surrounding areas on both sides are heated to about 350°C, kept warm for 2-3 hours, and then cooled naturally.

[0016] Optimal Solution 4: As a further optimization of Optimal Solution 3, the welding of each plate adopts a multi-layer and multi-pass welding process.

[0017] The purpose of improving welding quality is achieved by "preheating" the subsequent welds through the previous welds and "post-heat treating" the previous welds through the subsequent welds.

[0018] Optimal Option 5: As a further optimization of Optimal Option 4, the seat plate is forged from high-strength steel plates, the saddle groove bottom plate is forged from 30CrMo, and the high-strength steel plates are Q420qE grade steel plates.

[0019] In terms of material selection, in the cast-weld saddle structure, in order to ensure good weldability with the saddle body steel plate, the cast saddle head generally chooses weldable cast steel; and the highest material strength grade of weldable cast steel is ZG340-550H, and its yield strength is not less than 340MPa. The main saddle at this strength is seriously mismatched with the high-strength cast steel wire. And there are only four types of casting materials that meet the requirements of the saddle and meet the standards: ZG230-450H, ZG270-480H, ZG300-500H, and ZG340-550H. After adopting the forging process, there are as many as 75 types of selectable materials that meet the requirements, including 15 carbon steel forgings and 60 alloy steel forgings. This provides more possibilities for designing and manufacturing high-strength and high-performance saddles.

[0020] Based on the current matching demand of increasing the tensile strength of the main cable steel wire to 2000MPa, based on the accumulated experience of engineers and the comparison of relevant experimental structure analysis, 30CrMo forged steel is the first choice for the bottom forged steel parts; based on the weldability of the steel plate and the forged steel parts, Q420qE grade steel plate is selected.

[0021] Preferred solution six: As a further optimization of preferred solution five, the saddle groove bottom plate forming process is as follows: Step A: The cable saddle groove bottom plate is forged by a two-stage or three-stage segmented forging process, and the segmented forging is used to obtain the cable saddle groove bottom plate blank of each segment and perform heat treatment; Step B: performing rough machining on the saddle groove bottom plate blanks of each section to obtain rough-machined parts; After completing step 6, each section of the saddle assembly is subjected to mechanical finishing.

[0022] The main saddle groove bottom plate plays the main role in bearing the pressure and dispersing force of the steel cable. Based on its force requirements, the saddle groove bottom plate is designed as an arc structure; therefore, if the saddle groove is to be directly forged into an arc structure, a forging die must be used. However, the structural dimensions of the saddle are usually designed specifically according to the structure and span of the bridge. Generally, only 4 sets of saddles with the same structural dimensions are produced, that is, the manufacturing and production of the saddle does not meet the conditions for mass production. Forging dies are usually an effective means of mass production to improve efficiency, but the cost of forging dies is high, especially for large forging dies.

[0023] Based on cost considerations, this scheme adopts a die-free forging method, that is, a press is directly used to forge the raw materials into a rectangular billet similar in shape to the saddle groove bottom plate, and then the shape is formed by mechanical processing. However, since the saddle groove bottom plate is an arc-shaped structure, the rectangular billet needs to be cut a lot when the saddle groove bottom plate is forged as a whole and formed by mechanical processing, which will lead to a large amount of material waste. Therefore, in this scheme, the saddle groove bottom plate is forged in sections, and each section is combined to form a complete saddle groove bottom plate after rough machining. The curvature of each section is reduced, and the amount of material cutting is reduced, thereby reducing material waste. On the other hand, the saddle structure is large in size, and the one-piece forging of the saddle groove bottom plate requires a whole piece of forged steel for forging and forming, which also increases the procurement and acquisition cost of forged steel.

[0024] The cable saddle groove bottom plate is composed of multiple welded sections. If steps are formed at the joints of the sections, a relatively concentrated extrusion stress will be formed on the steel cable, which will have an adverse effect on the steel cable. Therefore, after the assembly of this scheme is completed, the cable saddle groove bottom plate is mechanically finished, and the whole is finished after assembly to reduce errors.

[0025] Preferred solution seven: As a further optimization of preferred solution six, step A includes the following steps: Step a1: put the steel ingot on a 3500 ton press, control the initial forging temperature at 1220°C and the final forging temperature at 850°C, perform chamfering, riser removal and other corrections on the steel ingot, and then return it to the heating furnace for further heating; Step a2: put the blank into a 3500-ton press, control the initial forging temperature at 1220°C and the final forging temperature at 850°C, and return the blank to the heating furnace for further heating after roughing and drawing. Step a3: put the blank into a 3500-ton press, control the initial forging temperature at 1220°C, and the final forging temperature at 850°C, perform a second upsetting and drawing process on the blank, and then return to the heating furnace for further heating; Step a4: Put it on a 3500-ton press, stretch it, trim it, and then put it into an annealing furnace for heat preservation; Step a5: After the planned number of products to be loaded into the annealing furnace is completed, the normalizing + tempering heat treatment process is started. The normalizing temperature is controlled at 880±15℃, and the tempering temperature is controlled at 650±10℃.

[0026] In the existing forging process of 30CrMo forged steel, the forging temperature is generally selected between 1100℃ and 850℃ in the normalizing or tempering state. However, the saddle groove bottom plate blank is large in size and heavy in weight, and it is difficult to transfer it between the heating furnace and the press. If it is to be transferred repeatedly, it is even more difficult; therefore, increasing the interval value of the initial forging temperature and the terminal temperature can reduce the number of transfers of the blank during the forging process. Secondly, the billet is heavy and thick, which also leads to slow heating inside the material. Therefore, appropriately increasing the heating temperature is conducive to increasing the heating rate. Secondly, the surface temperature of the billet is increased by using the temperature gradient inside and outside the billet. The impact on the material is mainly reflected in the reduction of the performance of the surface material. However, on the one hand, the surface material will be mechanically cut. On the other hand, the saddle groove bottom plate is in direct contact with the steel cable, and its surface strength requirement is less than that of the steel cable, which is beneficial to the steel cable. The saddle groove forged at this temperature is then subjected to the indentation test with the steel cable, which shows good matching performance with the steel cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of the main cable saddle in the present invention; Figure 2 This is a main cable saddle welding forming flow chart of the present invention; Figure 3 This is the finite element extrusion analysis diagram of ZG270-480H casting; Figure 4 This is the finite element extrusion analysis diagram of ZG300-500H casting; Figure 5 This is the finite element extrusion analysis diagram of 30CrMo forged steel. DETAILED DESCRIPTION

[0028] The following is further described in detail through specific implementation methods: The figure marks in the drawings of the specification include: bottom plate 01, side wall plate 02, saddle groove 10, saddle body structure 03, seat plate 04, main rib plate 31, middle partition plate 32, side rib plate 33, first vertical rib plate 41, and second vertical rib plate 42.

[0029] The embodiment is basically as shown in the attached Figure 1 To Attachment Figure 5 As shown: The main cable saddle structure design of forged and welded suspension bridge is shown in the attached figure. Figure 1 As shown, the main cable saddle is divided into three sections, which are composed of a front section, a middle section and a rear section connected by high-strength bolts. The joint surface of the front section and the middle section and the joint surface of the middle section and the rear section form an inverted trapezoidal wedge, and the inclination directions of the two joint surfaces relative to the horizontal plane are opposite.

[0030] Each section of the main saddle includes a seat plate 04, a saddle groove 10 and a supporting saddle body structure 03. The seat plate 04, the saddle groove 10 and the saddle body structure 03 are connected by welding. In order to enhance the connection strength between the saddle groove 10 and the saddle body structure 03, side ribs 33 are used to weld and connect the saddle groove 10 and the side of the saddle body structure 03.

[0031] The saddle groove 10 is welded by the bottom plate 01 and the side wall plate 02 to form a groove structure. The bottom plate 01 of the saddle groove is forged in three sections and then welded into a whole. The saddle body structure 03 is welded by steel plates, and the crisscrossing main rib plates 31 and the middle partition plate 32 are used as the saddle body structure 03. After the saddle body is connected to the side rib plates 33, two layers of vertical rib plates are set in the adjacent side rib plates 33 to connect with the base for reinforcement. The two sides of the first vertical rib plate 41 are located between the middle of the opposite surfaces of the adjacent side rib plates 33, and the bottom edge of the first vertical rib plate 41 is connected to the top surface of the seat plate 04; the side wall of the second vertical rib plate 42 is connected to the outer side of the two adjacent side rib plates 33, and the bottom edge of the second vertical rib plate 42 is also connected to the top surface of the base.

[0032] Since the main cable saddle mentioned above consists of many components, and its design adopts a forging and welding combined structural design in order to achieve lightweight, in order to match it with the 2000MPa level tensile strength of the main cable steel wire, rational design is required based on material selection, welding performance and welding planning. Therefore, after comprehensive analysis, the following forging and welding forming process of the main cable saddle of the suspension bridge is formed.

[0033] Step 1: Forging 1.1. The saddle groove bottom plate 01 is forged.

[0034] Material selection: The saddle trough bottom plate 01 uses 30CrMo forged steel ingots as raw materials. The steel ingots are required to be smelted in electric arc furnace (EAF) + ladle refining (LF) + vacuum deoxidation (VD) + argon protection casting; the saddle trough bottom plate 01 is forged in three sections to facilitate the selection of steel ingots and reduce the difficulty of processing.

[0035] Ingot charging: Special steel ingots are charged into the furnace in batches with the same furnace number and heated to the initial forging temperature.

[0036] Forging blank: The blank is forged by dieless forging, and a rectangular block equivalent to the corresponding section of the saddle groove bottom plate 01 is formed through shaping. The specific forging steps are as follows: (1) The steel ingot is taken out of the furnace and put into a 3500-ton press. After slight chamfering, clamping and riser removal, it is returned to the heating furnace for further heating. The starting forging temperature is 1220°C and the final forging temperature is 850°C. (2) The billet is taken out of the furnace and put into a 3500-ton press for upsetting and drawing. After the billet is drawn and made, it is returned to the heating furnace for further heating. The forging start temperature is 1220°C and the final forging temperature is 850°C. (3) The billet is taken out of the furnace and put into a 3500-ton press for a second upsetting and drawing process. After the billet is drawn and made, it is returned to the heating furnace for further heating. The initial forging temperature is (1220°C) and the final forging temperature is (850°C). (4) The billet is taken out of the furnace, put into a 3500-ton press, stretched, trimmed and formed, and then put into an annealing furnace for heat preservation; (5) When the planned number of products to be loaded into the annealing furnace is completed, the first heat treatment process (normalizing at 880±15℃ + tempering at 650±10℃) is started.

[0037] Mechanical rough machining: The forging blank is subjected to mechanical rough machining so that the rough-machined forgings can form the preliminary shape of the saddle groove bottom plate 01 after splicing.

[0038] Step 2: Selection and cutting of base plate 01 and steel plate materials: Based on the strength and weldability of different materials, the side wall plates 02 of the saddle groove 10 and the steel plate components that make up the saddle body structure 03 are made of Q420qE grade steel plates.

[0039] Step 3: Welding: Since the main saddle is composed of many components, the space between the components is narrow after assembly, which makes welding difficult. Cancelling some welding or welding strength due to space limitations requires comprehensive consideration from the overall structure of the saddle. Therefore, it is very important to identify the main welds and plan the welding sequence. The welding sequence is as shown in the attached figure. Figure 2 As shown, since the multi-section main saddles differ only in the shape of the side wall plate 02, Figure 2 Only one section of the welding and assembly process of the main saddle is shown.

[0040] 3.1. Preheating before welding: After completing the positioning welding of the parts to be welded, before starting to weld the weld, use a natural gas flame to preheat the welding groove and surrounding areas. The preheating temperature of Q420qE steel plate butt joints should be controlled at 100-150°C, and the preheating temperature of 30CrMo forgings should be controlled at 250~300°C; the preheating range is generally more than 75mm on each side of the weld, and the temperature is measured within 30~50mm from the weld.

[0041] 3.2. Welding of the saddle groove 10: Firstly, three sections of the rough-machined forgings of the saddle groove bottom plate 01 are welded together to form a whole, and then the side wall plates 02 are welded to both sides of the saddle groove bottom plate 01.

[0042] 3.3. Saddle body structure 03 welding The two main ribs 31 and the four middle partitions 32 are joined to the surface of the base by positioning welding through auxiliary beams. First, one of the main ribs 31 is vertically welded to the base, and then the four middle partitions 32 are positioned and welded between the side wall of the main rib 31 and the top surface of the base. Finally, another main rib 31 is welded, and the other end faces of the main rib 31 and the middle partition 32 are fixedly welded.

[0043] 3.4. Welding of the saddle groove 10 and the saddle body structure 03 The saddle groove 10 is placed on the saddle body structure 03 and spot welded to position it.

[0044] 3.5. Welding of the side rib plate 33 with the saddle body structure 03 and the cable saddle groove 10 (1) Weld the side ribs 33 on both sides of the saddle groove 10. There are four side ribs 33 on each side. The side ribs 33 are welded to the saddle groove 10, the main ribs 31, and the seat plate 04 respectively. The side ribs 33 have the function of stabilizing the main ribs 31 and the saddle groove 10. This welding step is conducive to welding the welds between the saddle groove bottom plate 01 and the side wall plate 02. (2) Weld the side ribs 33 to strengthen the seat plate 04, the saddle groove side wall plate 02, the saddle groove bottom plate 01, and the main ribs 31.

[0045] 3.6. Stiffener welding (1) Weld the first rib plate 41, and position the first rib plate 41 between adjacent side rib plates 33 along the length direction of the saddle groove 10. There are three first rib plates 41 on each side, and each first rib plate 41 passes through the same plane. The bottom edge of the first rib plate 41 is welded to the top surface of the seat plate 04, and then the side walls of the first rib plate 41 are respectively welded between the opposite surfaces of the adjacent side rib plates 33; (2) Weld the second rib plates 42 and position the second rib plates 42 between the outer edges of the adjacent side rib plates 33 along the length direction of the saddle groove 10. The second rib plates 42 are flush with the side edges of the side rib plates 33. There are three second rib plates 42 on each side. After the rib plates are welded, the first section of the main saddle is obtained. The remaining two sections of the main saddle are assembled according to the above process.

[0046] 3.7. Welding requirements for welds: Each weld adopts a multi-layer and multi-pass welding process, that is, a weld is completed through multiple passes of welding, and the subsequent weld covers the previous weld to gradually process the weld. The previous weld is used to "preheat" the subsequent weld, and the subsequent weld is "post-heat treated" for the previous weld to improve the welding quality.

[0047] 3.8. Post-weld heat treatment: After the key welds (mainly including ultra-thick plate welds) are welded, the welds and their surrounding areas on both sides are heated to about 350°C, kept warm for 2-3 hours and then cooled naturally to prevent hydrogen-induced cracks.

[0048] Step 4: Mechanical finishing. After completing the above steps, the three sections of the saddle groove bottom plate are assembled by high-strength bolts and then mechanically finished.

[0049] This prevents the appearance of steps between the saddle groove bottom plates due to processing errors after the final on-site assembly.

[0050] In terms of material selection, especially for the saddle groove bottom plate 01 directly bearing the pressure of the steel cable, the material selection is crucial. In the material selection experiment, in order to match the steel cable wires of the 2000 MPa grade, the yield strength of the forged steel material should reach the target of not less than 390 MPa. Based on past work experience, the engineer carried out a comparative study on the strength index of the forged steel materials required for the forged-welded combined saddle for three materials: 30CrMo, 20CrMnMo, and 20CrNiMo. The research results show that while the strength index of the forged steel 30CrMo material meets the requirements, the slope is gentler, and the material has relatively consistent mechanical properties from the core to the surface, which can be used as the preferred forged steel material for the saddle. At the same time, the impact resistance performance of the 30CrMo material was further studied under different low-temperature conditions, and this material has relatively excellent low-temperature toughness. The test results of the forged steel 30CrMo + Q420qE welded test plate show that the MT test of the welding evaluation test plate meets the requirements of Grade 1 in GB / T 26952-2011, and the UT test meets the requirements of Grade I in NB / T47013.3-2015. The performance of the structural welds all meets the requirements of the high-performance forged-welded combined saddle, forming good quality and efficiency.

[0051] Through the finite element analysis of the steel components cast with different types of raw materials and 30CrMo forged steel, and the extrusion test of the cable strands and the saddle groove, as shown in the attached drawings, the following conclusions are obtained: (1) The order of the indentation depth is: 30CrMo < ZG300-500H < ZG270-480H, and the finite element analysis results of the indentation depth of the forging 30CrMo are relatively uniform.

[0052] (2) The order of the number of plastic deformation units entered is 30CrMo < ZG300-500H < ZG270-480H.

[0053] (3) Among the three research materials, the forged steel 30CrMo material has better anti-extrusion deformation ability, higher surface hardness, and the cost is also the steel to be considered first. It can be used as the forged steel material for the bottom pressure-bearing component of the saddle groove of the forged-welded combined saddle.

[0054] Combined with the finite element analysis and extrusion test, the reasonable form and performance of the forged-welded combined saddle structure are analyzed. The forged-welded combined lightweight saddle uses high-strength forged steel (30CrMo) + Q420qE to replace the cast-welded saddle (ZG270-480H + Q345R). The overall strength of the structure is increased by 44%, and at the same time, the weight of the main saddle is reduced by 26% respectively, achieving the purpose of high strength and lightweight of the saddle structure. The use of Q420qE grade forged steel has higher strength, can effectively prevent the erosion of the main cable on the saddle and compression deformation, and the quality has been greatly improved.

[0055] In terms of welding performance, the MT test of the welding evaluation test plate meets the requirements of GB / T 26952-2011 Level 1, and the UT test meets the requirements of NB / T47013.3-2015 Level I. The performance of the structural welds meets the requirements of high-performance forged and welded cable saddles, forming a good quality benefit.

[0056] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. The forging and welding forming process of the main cable saddle of the suspension bridge is characterized by: The main cable saddle is composed of a seat plate, a cable saddle groove and a saddle body structure welded from high-strength steel plates. The cable saddle groove is composed of a bottom plate and a side wall plate blanked from high-strength steel plates. The main cable saddle is designed with a two-section or three-section structure and connected into a whole by high-strength bolts. The forging and welding forming process of the main cable saddle includes the following steps: Step 1: Forming the bottom plate of the saddle groove by forging process; The saddle groove bottom plate forming process is as follows: Step A: The cable saddle groove bottom plate is forged by a two-stage or three-stage segmented forging process, and the segmented forging is used to obtain the cable saddle groove bottom plate blank of each segment and perform heat treatment; Step B: performing rough machining on the saddle groove bottom plate blanks of each section to obtain rough-machined parts; The step A comprises the following steps: Step a1: put the steel ingot on a 3500 ton press, control the initial forging temperature at 1220°C and the final forging temperature at 850°C, perform chamfering, riser removal and other corrections on the steel ingot, and then return it to the heating furnace for further heating; Step a2: put the blank into a 3500-ton press, control the initial forging temperature at 1220°C and the final forging temperature at 850°C, and return the blank to the heating furnace for further heating after roughing and drawing. Step a3: put the blank into a 3500-ton press, control the initial forging temperature at 1220°C, and the final forging temperature at 850°C, perform a second upsetting and drawing process on the blank, and then return to the heating furnace for further heating; Step a4: Put it on a 3500-ton press, stretch it, trim it, and then put it into an annealing furnace for heat preservation; Step a5: After the planned number of products to be loaded into the annealing furnace is completed, the normalizing + tempering heat treatment process is started, and the normalizing temperature is controlled at 880±15℃, and the tempering temperature is controlled at 650±10℃; Step 2: Cut the components of the saddle body structure and the side wall panels of the saddle groove; Step 3: Weld the bottom plate of the saddle groove to the side wall plate to obtain the saddle groove; Step 4: Two main rib plates and multiple middle partition plates are joined on the seat plate surface by positioning welding. The two main rib plates are arranged relatively parallel, and the middle partition plates are distributed between the two main rib plates along the length direction of the main rib plates to form a grid structure, thus completing the welding of the seat plate and the saddle body structure; Step 5: Position the saddle groove on the saddle body structure, and use single-sided welds to weld the main rib plate of the saddle body structure and the middle partition plates at both ends to the bottom surface of the saddle groove to complete the combined welding of the saddle groove and the saddle body structure; Step 6: Position side rib plates perpendicular to the main rib plates between the side wall plates and the seat plates on both sides of the saddle groove, and weld the side rib plates to the main rib plates, the seat plates, the bottom plates of the saddle groove, and the side wall plates of the saddle groove by double-sided welds; Step 7: Weld the vertical rib plates between the adjacent side rib plates on both sides of the saddle body structure; After completing step 7, the saddle sections are assembled and then subjected to mechanical finishing.

2. The forging and welding forming process of the main cable saddle of a suspension bridge according to claim 1 is characterized in that: The vertical rib plate includes a first vertical rib plate and a second vertical rib plate. The bottom edge of the first vertical rib plate is welded to the top surface of the seat plate, and the side walls of the first vertical rib plate are respectively welded between the middle parts of the opposite surfaces of adjacent side rib plates; the bottom edge of the second vertical rib plate is welded to the top surface of the seat plate, and the plane where the second vertical rib plate is located is flush with the side edges of the adjacent side rib plates.

3. The forging and welding forming process of the main cable saddle of a suspension bridge according to claim 2 is characterized in that: During welding, after completing the positioning welding of the components, use a natural gas flame to preheat the welding groove and surrounding areas. The preheating temperature of high-strength steel plates should be controlled at 100-150℃, and the preheating temperature of forgings should be controlled at 250~300℃.

4. The forging and welding forming process of the main cable saddle of a suspension bridge according to claim 3 is characterized in that: After the welding of the welds on the bottom plate and the bottom block of the saddle groove is completed, the weld and its two sides are heated to about 350℃, kept warm for 2-3 hours and then cooled naturally.

5. The forging and welding forming process of the main cable saddle of a suspension bridge according to claim 4 is characterized in that: The welding of each plate adopts multi-layer and multi-pass welding process.

6. The forging and welding forming process of the main cable saddle of a suspension bridge according to claim 5 is characterized in that: The seat plate is forged from a high-strength steel plate, the saddle groove bottom plate is forged from 30CrMo, and the high-strength steel plate is a Q420qE grade steel plate.

Images