Forge welding forming process for splay 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 splay cable saddle of the suspension bridge, which mainly comprises the following steps: (1) forming a bottom block and a bottom plate of a cable saddle groove by adopting a forging process, (2) blanking a plate, and (3) welding the bottom plate of the cable saddle groove and a side wall plate to obtain the cable saddle groove. And (4) the welding sequence of the frame plates is planned to obtain the optimal welding space and welding quality. In the traditional process, the cable saddle groove is usually formed by casting, so that the cable saddle groove is moderate in quality and low in strength, and the cable saddle groove bottom plate in the scheme is formed by forging so as to achieve the purposes of light weight and improved strength.

Description

Technical Field

[0001] The invention relates to the application of forging and welding technology in the manufacturing and forming of suspension bridge cable saddles, and in particular to a forging and welding forming process of suspension bridge loose cable saddles. 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. The whole bridge generally has 4 sets of main saddles and 4 sets of loose saddles. In the large-span suspension bridge, traditional cast saddles are used. The total weight of each set of loose saddles reaches 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 purpose of the present invention is to provide a forging and welding forming process for a suspension bridge loose cable saddle, so as to improve the strength of the loose cable saddle and realize the lightweight of the loose cable saddle, and to reduce the welding difficulty and ensure the product quality by reasonably planning the welding process.

[0007] The loose cable saddle is composed of a bottom block, a saddle groove and a frame welded from high-strength steel plates. The saddle groove is composed of a bottom plate and a side wall plate blanked from high-strength steel plates. The forging and welding forming process of the loose cable saddle of a suspension bridge includes the following steps:

[0008] Step 1: Forming the bottom block and the bottom plate of the saddle groove by forging process;

[0009] Step 2: Cutting the components of the frame and the side wall panels of the saddle groove;

[0010] Step 3: Weld the bottom plate of the saddle groove to the side wall plate to obtain the saddle groove;

[0011] Step 4: Spot weld two transverse ribs, two longitudinal ribs and a small rib on the same plane as the transverse rib on the bottom block. The two longitudinal ribs are relatively parallel. The transverse ribs are distributed along the length of the plot on both sides of the longitudinal rib to form a crisscross structure, and the bottom block and the frame body are welded together;

[0012] Step 5: Position the saddle groove on the frame body, complete the combined welding of the saddle groove and the frame body, and weld small rib plates connecting the longitudinal rib plates and the bottom plate of the saddle groove on both sides and between the longitudinal rib plates;

[0013] Step 6: Position the side plate perpendicular to the transverse rib plate on the side of the transverse rib plate, and weld the side plate to the transverse rib plate, the bottom block, and the bottom plate of the saddle groove; weld a number of transverse rib plates connecting the side plate, the bottom plate of the saddle groove, and the side wall plate of the saddle groove on both sides of the saddle groove;

[0014] Step 7: The frame sides corresponding to both ends of the saddle groove are welded and closed with three end plates.

[0015] The beneficial effects of this solution are:

[0016] (1) The saddle groove of the loose cable 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 amount of material 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 amount of material. The side wall plate of the saddle groove is not the main load-bearing part. 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". The frame 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.

[0017] (2) In the traditional loose 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 loose 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 partition connecting the saddle head and the saddle seat usually plays a role in transmitting force. In this scheme, the longitudinal rib plate, the transverse rib plate and the small rib plate play a role in transmitting force from the cable saddle groove to the frame. If the traditional idea of ​​first forming the saddle head and the saddle seat and then welding the saddle head and the saddle seat together is adopted, it is impossible to fully weld the cable saddle groove bottom plate with the longitudinal rib plate, the transverse rib plate and the small rib plate with double-sided flux, which will result in insufficient welding strength.

[0018] (3) This scheme first welds the transverse ribs and longitudinal ribs to the bottom block in a vertical and horizontal positioning manner, and welds a small rib plate at the same time, which is more conducive to the transverse ribs and longitudinal ribs forming a stable structure; then the saddle groove is welded to the longitudinal rib plate, so that welding space for the transverse ribs and small ribs can be reserved, which is convenient for ensuring the connection strength between the frame and the saddle groove; finally, the side plates, end plates and other surrounding structures of the frame are welded to enhance the stability of the frame.

[0019] Preferred solution 1: As a further optimization of the basic solution, the longitudinal rib plate is formed by welding a large plate welded to the bottom plate of the saddle groove and a small plate welded to the bottom block; in step 4, the large plate and the small plate are first butt-welded to form a longitudinal rib plate, and after two transverse rib plates and a small rib plate are spliced ​​on the same plane through an auxiliary beam, the transverse rib plates and the longitudinal rib plates are positioned and welded to the bottom block.

[0020] The longitudinal rib plate is welded together by large plates and small plates. On the one hand, the plate can be fully utilized. On the other hand, a longer single-direction weld will be formed between the transverse rib plate and the longitudinal rib plate. After the longitudinal rib plate is composed of large plates and small plates, the weld between the transverse rib plate and the longitudinal rib plate crosses with the weld of the large plate and the small plate, which can avoid stress concentration.

[0021] After two transverse ribs and a small rib are spliced ​​on the same plane through auxiliary beams, they are staggered with the longitudinal ribs for easy positioning. A gap should be formed between the transverse ribs and the small ribs for the upper end of the longitudinal ribs to be inserted, so that a stable structure can be formed between the transverse ribs and the longitudinal ribs through welding; if the transverse ribs and the small ribs are spliced ​​on the same plane and a gap is reserved, it will be difficult for the transverse ribs and the small ribs to form a stable structure; after the positioning and welding of the transverse ribs, small ribs and longitudinal ribs are completed, the auxiliary beam can be cut.

[0022] 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.

[0023] 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.

[0024] Preferred solution three: As a further optimization of preferred solution two, 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 to prevent hydrogen-induced cracks.

[0025] Optimal Option 4: As a further optimization of Optimal Option 1, the welding of each plate adopts a multi-layer and multi-pass welding process; the previous pass "preheats" the subsequent welds, and the subsequent welds "post-heat treat" the previous welds, so as to achieve the purpose of improving welding quality.

[0026] Preferred solution five: As a further optimization of preferred solution two, the bottom block is forged from Q345R, the saddle groove bottom plate is forged from 30CrMo, and the high-strength steel plate is Q420qE grade steel plate.

[0027] 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.

[0028] 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.

[0029] Preferred solution six: As a further optimization of preferred solution five, the saddle groove bottom plate forming process is as follows:

[0030] 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;

[0031] Step B: performing rough machining on the saddle groove bottom plate blanks of each section to obtain rough-machined parts;

[0032] Step C: welding each section of the rough-machined parts to obtain the saddle groove bottom plate;

[0033] After completing step 6, the saddle groove bottom plate is subjected to mechanical finishing.

[0034] The bottom plate of the cable saddle groove plays the main role in bearing the pressure and dispersing force of the steel cable. Based on its force requirements, the bottom plate of the cable saddle groove is designed as an arc structure; therefore, if the cable saddle groove is to be directly forged into an arc structure, a forging die must be used. However, the structural dimensions of the cable saddle are usually designed specifically according to the structure and span of the bridge. Generally, only 4 sets of cable saddles with the same structural dimensions are produced, that is, the manufacturing and production of cable saddles 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.

[0035] 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 in conjunction with 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 in conjunction with mechanical processing, which will result in a large amount of material waste. Therefore, in this scheme, the saddle groove bottom plate is forged in sections, and each section is welded to form a complete saddle groove bottom plate after rough machining; the curvature of each section is reduced, and the amount of material cutting can be 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.

[0036] The saddle groove bottom plate is composed of multiple sections welded together. During the welding process, there will inevitably be errors, and the steps formed at the joints of each section will form a relatively concentrated extrusion stress on the steel cable, thereby having an adverse effect on the steel cable; therefore, this solution is to perform mechanical finishing on the saddle groove bottom plate after assembly is completed.

[0037] Preferred solution seven: As a further optimization of preferred solution six, step A comprises the following steps:

[0038] 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;

[0039] 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.

[0040] 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;

[0041] Step a4: Put it on a 3500-ton press, stretch it, trim it, and then put it into an annealing furnace for heat preservation;

[0042] 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℃.

[0043] 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.

[0044] Preferred Option 8: As a further optimization of Preferred Option 7, the steel ingot or billet is heated in a heating furnace, the heating furnace includes a first heating furnace and a second heating furnace, a 3,500-ton press is arranged between the first heating furnace and the second heating furnace, a chain plate conveyor belt is arranged between the furnace mouth of the first heating furnace, the forging table of the 3,500-ton press and the furnace mouth of the second heating furnace to transport the steel ingot or billet, and the forging table of the 3,500-ton press can be raised and lowered; after the steel ingot or billet is heated up in the first heating furnace, the forging table of the 3,500-ton press is lowered to below the chain plate conveyor belt, and the steel ingot or billet is transported to the forging table of the 3,500-ton press by the chain plate conveyor belt. After the temperature of the steel ingot or billet is reduced to the final forging temperature, the forging table of the 3,500-ton press is lifted to a height flush with the chain plate conveyor belt, and the billet is transported to the second heating furnace by the chain plate conveyor belt for heating again.

[0045] In the process of using a chain plate conveyor belt to transport steel ingots or billets from the heating furnace to the forging table of a 3,500-ton press, when the steel ingots or billets reach the junction of the chain plate conveyor belt and the forging table, if the chain plate conveyor belt and the forging table are in a flush state, as the contact area between the steel ingots or billets and the chain plate conveyor belt becomes smaller and smaller, the chain plate conveyor belt cannot completely deliver the steel ingots or billets to the forging table; by lowering the height of the forging table, the chain plate conveyor belt can throw the steel ingots or billets to the forging table, so that the steel ingots or billets can directly enter the forging table. When the steel ingots or billets need to return to the heating furnace, due to the large mass of the steel ingots, the steel ingots falling onto the chain plate conveyor belt can easily cause damage to the chain plate conveyor belt. Therefore, when the steel ingots or billets need to return to the heating furnace, the forging table is lifted to a height flush with the chain plate conveyor belt, and the steel ingots or billets are manually pushed into the chain plate conveyor belt. The use of a chain conveyor belt in conjunction with the lifting and lowering of the forging table to transfer the steel ingots or billets can effectively reduce the difficulty of transferring the steel ingots or billets and improve the transfer efficiency.

[0046] In addition, in the process of forging steel ingots, it is also necessary to adjust the position of the steel ingots, turn over and other operations. Usually, the steel ingots are clamped by a clamp for related operations, and the position is relatively easy to move; but when it comes to turning over operations, it often requires the cooperation of multiple people and is relatively time-consuming. In this scheme, by moving the steel ingots to the chain conveyor belt, and then lowering the forging table to form a drop between the chain conveyor belt and the forging table, and making the chain conveyor belt return the steel ingot to the forging table, the drop is used and the steel ingot is controlled by clamping the steel ingot with a clamp, which can reduce the difficulty of turning over operations. Secondly, in bridge construction, four sets of main cable saddles and loose cable saddles are required, and the bottom plate of the cable saddle groove is designed in sections. The same batch of forged steel ingots may involve more than ten or even more than twenty pieces, and a single steel ingot involves multiple forgings. Therefore, the use of two heating furnaces in conjunction with the forging press is conducive to batch management of steel ingots. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a structural diagram of the loose cable saddle in the present invention;

[0048] Figure 2 This is a flow chart of the welding formation of the loose cable saddle of the present invention;

[0049] Figure 3 This is the finite element extrusion analysis diagram of ZG270-480H casting;

[0050] Figure 4 This is the finite element extrusion analysis diagram of ZG300-500H casting;

[0051] Figure 5 This is the finite element extrusion analysis diagram of 30CrMo forged steel.

[0052] The figure marks in the drawings of the specification include: bottom plate 01, side wall plate 02, saddle groove 10, frame structure 03, transverse rib plate 111, transverse rib plate 31, small rib plate 32, longitudinal rib plate 33, side plate 34, end plate 35, bottom block 04. DETAILED DESCRIPTION

[0053] The following is further described in detail through specific implementation methods:

[0054] Embodiment 1:

[0055] The design of loose cable saddle structure of forged and welded suspension bridge is shown in the attached Figure 1 and attached Figure 2 As shown, the loose cable saddle consists of a bottom block 04, a cable saddle groove 10 and a supporting frame structure 03. The bottom block 04, the cable saddle groove 10 and the frame structure 03 are connected by welding. In order to enhance the connection strength between the cable saddle groove 10 and the frame structure 03, a transverse rib plate 111 is used to weld and connect the cable saddle groove 10 and the side of the frame structure 03.

[0056] The saddle trough 10 is welded to form a trough structure by welding the bottom plate 01 of the saddle trough 10 and the side wall plate 02. The bottom plate 01 of the saddle trough 10 is forged in three sections and then welded into a whole. The frame structure 03 is welded by steel plates, and the frame body is composed of crisscrossed transverse ribs 31 and longitudinal ribs 33. The frame is reinforced by small ribs 32, and end plates 35 and side walls are provided around for reinforcement and sealing.

[0057] Since there are many components constituting the above-mentioned loose cable saddle, and in order to achieve lightweight, its design adopts a forging and welding combined structural design. 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 loose cable saddle of the suspension bridge is formed.

[0058] Step 1: Forging

[0059] 1.1. The bottom plate 01 of the saddle groove 10 is forged.

[0060] Material selection: The bottom plate 01 of the saddle trough 10 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 bottom plate 01 of the saddle trough 10 is forged in three sections to facilitate the selection of steel ingots and reduce the difficulty of processing.

[0061] Ingot charging: Special steel ingots are charged into the furnace in batches with the same furnace number and heated to the initial forging temperature.

[0062] Forging billet: The billet forging adopts dieless forging, and a rectangular block corresponding to the saddle groove 10 bottom plate 01 is formed by plastic processing. The specific forging steps are as follows:

[0063] (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.

[0064] (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.

[0065] (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).

[0066] (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;

[0067] (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.

[0068] Mechanical rough machining: The forging blank is subjected to mechanical rough machining so that the rough-machined forgings can form a preliminary shape of the bottom plate 01 of the saddle groove 10 after being spliced.

[0069] 1.2. Forging of bottom block 04: bottom block 04 is forged with Q345R steel ingot. Since bottom block 04 is a trapezoidal block composed of straight planes, a simple mold can be made to forge it directly.

[0070] Step 2: Steel plate material selection and cutting: Based on the strength and weldability of different materials, the side wall plates 02 of the saddle trough 10 and the steel plate components that make up the frame structure 03 are made of Q420qE grade steel plates.

[0071] Step 3: Welding: Since the loose cable saddle is composed of many components, the space between the components is narrow after assembly, which makes welding difficult. Cancelling some welding or reducing welding strength due to space limitations requires comprehensive consideration from the overall structure of the cable 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 shown.

[0072] 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 and Q345R 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.

[0073] 3.2. Welding of the saddle groove 10: First, three sections of the rough-machined forgings of the bottom plate 01 of the saddle groove 10 are welded together to form a whole, and then the side wall plates 02 are welded to both sides of the bottom plate 01 of the saddle groove 10.

[0074] 3.3. Frame body welding:

[0075] (1) Two transverse ribs 31 and one small rib 32 are joined together in the same plane by positioning welding through an auxiliary beam, and a gap is reserved between the two transverse ribs 31 and the small rib 32 for the longitudinal rib 33 to be embedded, so as to position the transverse ribs 31 and the longitudinal rib 33; the auxiliary beam is arranged on the arc-shaped edge on the upper side of the transverse rib 31 and the small rib 32, and in order to enhance stability, reinforcing ribs can be spot welded on the side of the transverse rib 31, the small rib 32 and the auxiliary beam;

[0076] (2) The longitudinal rib plate 33 is formed by splicing a large plate at the top and a small plate at the bottom. The large plate and the small plate need to be welded to form the longitudinal rib plate 33;

[0077] (3) First, the transverse rib plate 31 is positioned and welded on the bottom block 04 along the length direction of the bottom block 04, and then the longitudinal rib plate 33 is inserted from one side into the gap between the transverse rib plate 31 and the small rib plate 32 to form a crisscross structure. After adjustment, the positioning is completed, and each weld is welded to obtain the frame body;

[0078] (4) Remove the auxiliary beams and reinforcement ribs.

[0079] Since the bottom block 04 is a regular rectangular block structure, the frame body is positioned on the bottom block 04 to facilitate stability during positioning; and the transverse rib plate 31 is first welded on the bottom block 04, and the side of the transverse rib plate 31 and the gap between the transverse rib plate 31 and the small rib plate 32 are used to facilitate positioning of the longitudinal rib plate 33.

[0080] 3.4. Welding of the saddle groove 10 and the frame body:

[0081] (1) Place the saddle groove 10 on the frame body and perform spot welding to position it;

[0082] (2) Invert the frame body so that the saddle groove 10 faces downward, and apply welds to the welds between the longitudinal rib plate 33, the transverse rib plate 31 and the bottom plate 01 of the saddle groove 10; the weld between the longitudinal rib plate 33 and the bottom plate 01 of the saddle groove 10 is the most important weld connecting the frame mechanism and the saddle groove 10. This welding sequence allows the weld to have sufficient welding space, which is conducive to ensuring welding quality;

[0083] (3) Small ribs 32 are welded between the longitudinal ribs 33 and on both sides. The small ribs 32 are welded gradually toward the two ends of the saddle groove 10 with the transverse ribs 31 as the center, so as to form a good welding space; the small ribs 32 are used to strengthen the transverse weld between the frame and the saddle groove 10.

[0084] 3.5. Welding of side plate 34 and transverse rib plate 111:

[0085] (1) Welding the side plates 34 on both sides of the saddle groove 10, and respectively welding the side plates 34 to the transverse rib plate 31, the bottom block 04 and the saddle groove 10; the side plates 34 have the function of stabilizing the transverse rib plate 31 and the saddle groove 10, and this welding step is conducive to welding each weld seam on the transverse rib plate 31;

[0086] (2) Welding the transverse rib plate 31 to strengthen the side plate 34, the bottom plate 01 of the saddle groove 10 and the side wall plate 02 of the saddle groove 10.

[0087] 3.6. Welding of end plates 35: The two sides of the frame body corresponding to both ends of the saddle groove 10 are welded and closed with three end plates 35 respectively.

[0088] 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. The subsequent weld covers the previous weld to gradually process the weld. The previous weld "preheats" the subsequent weld, and the subsequent weld "post-heat treats" the previous weld to improve the welding quality.

[0089] 3.7. Post-weld heat treatment: After the key welds (mainly including the welds of ultra-thick plates) are welded, the welds and their surrounding areas on both sides are heated to about 350 °C, kept warm for 2 - 3 h, and then cooled naturally to prevent hydrogen-induced cracks.

[0090] Step 4: Machining finish: After completing the above steps, the bottom plate 01 of the saddle groove 10 is machined.

[0091] In terms of material selection, especially the material selection of the bottom plate 01 of the saddle groove 10 that directly bears the pressure of the steel cable is crucial. In the material selection experiment, to match the steel cable wire of 2000 MPa level, 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, and can be used as the preferred forged steel material for the saddle. At the same time, the impact resistance of the 30CrMo material under different low-temperature conditions was further studied, and this material has relatively excellent low-temperature toughness. The test results of the forged steel 30CrMo + Q420qE welding 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 better quality and efficiency.

[0092] Through finite element analysis and the extrusion test of the cable strands and the saddle groove with a three-coordinate measuring machine by using steel components cast from different types of raw materials and 30CrMo forged steel, as shown in the appendix Figure 3-5 as follows, the following conclusions are obtained:

[0093] (1) The order of the indentation depth is: 30CrMo < ZG300 - 500H < ZG270 - 480H, and the finite element analysis result of the indentation depth of the forging 30CrMo is relatively uniform.

[0094] (2) The order of the number of plastic deformation units is 30CrMo <ZG300-500H<ZG270-480H。

[0095] (3) Among the three research materials, forged steel 30CrMo material has better anti-extrusion deformation ability, higher surface hardness, and is the preferred steel material in terms of cost. It can be used as the forged steel material for the pressure-bearing component at the bottom of the saddle groove of the forged and welded combined cable saddle.

[0096] Combined with finite element analysis and extrusion test, the reasonable form and performance of the forged and welded combined saddle structure were analyzed. The forged and 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 the weight of the main saddle is reduced by 26%. The purpose of high strength and lightweight of the saddle structure is achieved. The use of Q420qE-grade forged steel has higher strength and can effectively prevent the main cable from eroding the saddle and compressive deformation, and the quality is greatly improved.

[0097] 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.

[0098] Embodiment 2:

[0099] The difference between the second embodiment and the first embodiment is that the second embodiment integrates the forging equipment involved in the saddle groove bottom plate 01. Specifically, the heating furnace for heating the steel ingot and the billet includes a first heating furnace and a second heating furnace, the 3500-ton press is arranged between the first heating furnace and the second heating furnace, and a chain plate conveyor belt is arranged between the furnace mouth of the first heating furnace, the forging table of the 3500-ton press and the furnace mouth of the second heating furnace to transport the steel ingot or billet, and the running direction of the chain plate conveyor belt can be changed, so as to realize the conversion of discharging and returning materials.

[0100] The forging table of the 3,500-ton press can be raised and lowered. The lifting of the forging table is driven by a hydraulic cylinder. A pedestal is provided under the forging table. When the forging table is lowered to the lowest position, the forging table falls on the pedestal and is supported by the pedestal. During the forging process of the ingot or billet, the forging table is supported by the pedestal.

[0101] After the ingot or billet is heated up in the first heating furnace, the forging table of the 3500-ton press is lowered below the chain plate conveyor belt, and the ingot or billet is transported to the forging table of the 3500-ton press via the chain plate conveyor belt. After the temperature of the ingot or billet is reduced to the final forging temperature, the forging table of the 3500-ton press is lifted to the same height as the chain plate conveyor belt, and the billet is sent to the second heating furnace via the chain plate conveyor belt for heating again. In the process of turning over the ingot or billet, the ingot is moved onto the chain plate conveyor belt, and then the forging table is lowered to form a drop between the chain plate conveyor belt and the forging table, and the chain plate conveyor belt is used to send the ingot back to the forging table. The drop is used to control the ingot by clamping the ingot with the clamp, which can reduce the difficulty of the turning operation.

[0102] 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 loose cable saddle of the suspension bridge is characterized by: The loose cable saddle is composed of a bottom block, a cable saddle groove and a frame 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 forging and welding forming process of the loose cable saddle includes the following steps: Step 1: Forming the bottom block and the bottom plate of the saddle groove by forging process; The bottom block is forged from Q345R, and the bottom plate of the saddle groove is forged from 30CrMo; 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; 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 B: performing rough machining on the saddle groove bottom plate blanks of each section to obtain rough-machined parts; Step C: welding each section of the rough-machined parts to obtain the saddle groove bottom plate; Step 2: Cutting the components of the frame 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 transverse ribs and a small rib are welded together on the same plane through auxiliary beams, and a gap is reserved between the two transverse ribs and the small rib for the longitudinal rib to be embedded. The auxiliary beam is set on the arc edge on the upper side of the transverse rib and the small rib; the transverse rib is welded to the bottom block along the length direction of the bottom block, and then the longitudinal rib is inserted from one side into the gap between the transverse rib and the small rib to form a crisscross structure. After adjustment, the positioning is completed, and each weld is welded to obtain the frame body and the auxiliary beam is removed; Step 5: Position the saddle groove on the frame body, complete the combined welding of the saddle groove and the frame body, and weld small rib plates connecting the longitudinal rib plates and the bottom plate of the saddle groove on both sides and between the longitudinal rib plates; Step 6: Position the side plate perpendicular to the transverse rib plate on the side of the transverse rib plate, and weld the side plate, the transverse rib plate, the bottom block, and the bottom plate of the saddle groove; weld a number of transverse rib plates connecting the side plate, the bottom plate of the saddle groove, and the side wall plate of the saddle groove on both sides of the saddle groove; and then perform mechanical finishing on the bottom plate of the saddle groove; Step 7: The frame sides corresponding to both ends of the saddle groove are welded and closed with three end plates.

2. The forging and welding forming process of the loose cable saddle of a suspension bridge according to claim 1 is characterized in that: The longitudinal rib plate is formed by butt-welding a large plate welded to the bottom plate of the saddle groove and a small plate welded to the bottom block; in step 4, the large plate and the small plate are first butt-welded to form the longitudinal rib plate, and after two transverse rib plates and a small rib plate are spliced ​​on the same plane through auxiliary beams, the transverse rib plates and the longitudinal rib plates are positioned and welded to the bottom block.

3. The forging and welding forming process of the loose 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 loose 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 welds and the surrounding areas on both 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 loose cable saddle of the 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 loose cable saddle of a suspension bridge according to claim 5 is characterized in that: The high-strength steel plate is a Q420qE grade steel plate.

7. The forging and welding forming process of the loose cable saddle of a suspension bridge according to claim 6 is characterized in that: The steel ingot or billet is heated in a heating furnace, which includes a first heating furnace and a second heating furnace. A 3,500-ton press is arranged between the first heating furnace and the second heating furnace. A chain plate conveyor belt is arranged between the furnace mouth of the first heating furnace, the forging table of the 3,500-ton press and the furnace mouth of the second heating furnace to transport the steel ingot or billet. The forging table of the 3,500-ton press can be raised and lowered. After the steel ingot or billet is heated up in the first heating furnace, the forging table of the 3,500-ton press is lowered below the chain plate conveyor belt, and the steel ingot or billet is transported to the forging table of the 3,500-ton press by the chain plate conveyor belt. After the temperature of the steel ingot or billet is reduced to the final forging temperature, the forging table of the 3,500-ton press is lifted to a height flush with the chain plate conveyor belt, and the billet is transported to the second heating furnace by the chain plate conveyor belt for heating again.

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