Turnover type high-strength pipeline bolt fastener

Abstract

The invention relates to the technical field of bolt fasteners, and discloses an overturning type high-strength pipeline bolt fastener which comprises a screw rod, internal threads are formed in the outer wall of the screw rod, a nut is connected to the outer wall of the screw rod in a threaded mode, a flange plate is arranged on the lower portion of the nut, and an overturning block is arranged on the lower portion of the flange plate. A rotating groove is formed in the outer wall of the screw rod, the overturning blocks are located in the rotating groove, the overturning blocks and the rotating groove are arranged in an annular array with the circle center of the screw rod as the circle center, a rotating ring is arranged on the lower portion of the rotating groove, fixing holes are formed in the lower portions of the overturning blocks, and the rotating ring is located in the fixing holes. And first friction teeth are arranged on the side edge, close to the screw rod, of the overturning block. According to the turnover bolt, through the first friction teeth arranged on the outer wall of the turnover block, large friction force can be generated between the turnover block and the flange plate after the turnover block is opened, and therefore the problems that a traditional bolt is inconvenient to bend in the pipeline engineering, external force is applied to a nut and a bolt head at the same time, and a pipeline joint is difficult to fasten are solved.

Description

Technical Field

[0001] The invention relates to the technical field of bolt fasteners, in particular to a flip-type high-strength pipeline bolt fastener. Background Art

[0002] In the wide application field of industrial pipeline systems, the stability and sealing of pipeline connections have always been key considerations, which highlights the importance of bolt fasteners for pipelines. Traditional pipeline connection methods have undergone a long development process. In the early days, simple rope bundling or simple metal clamps were used to fix pipelines, but such methods were only suitable for low-pressure, small-diameter pipeline systems with low sealing requirements. With the acceleration of industrial progress, its reliability could not meet the growing needs of complex working conditions. Subsequently, welding connections gradually emerged, which can provide higher connection strength. However, the welding process requires professional equipment and skills, and it is extremely inconvenient to disassemble the pipeline during later maintenance or modification, which will cause irreversible damage to the pipeline. Against this background, bolt fasteners came into being. It can achieve fast and convenient installation and disassembly without destroying the integrity of the pipeline structure, greatly reducing the maintenance cost and difficulty of the pipeline system. Moreover, by precisely controlling the preload force of the bolts, it is possible to effectively adapt to the connection requirements of pipelines with different pressure levels and different media transmissions. Whether it is high-pressure corrosion-resistant pipelines in the petrochemical industry or ordinary plumbing pipelines, bolt fasteners have become an indispensable key component for pipeline connections due to their flexibility, reliability and economy, and have strongly promoted the continuous development and progress of modern pipeline engineering technology.

[0003] Traditional bolts require external force to be applied to both the nut and the bolt head at the same time in order to be tightened. However, there are often narrow corners at the bends in pipeline projects, which makes it inconvenient to apply external force to both the nut and the bolt head at the same time, making it difficult to tighten the pipe joints. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a flip-type high-strength pipeline bolt fastener, which solves the problem that traditional bolts require external force to be applied to the nut and the bolt head at the same time in order to be tightened. However, there are often narrow corners at the bends in pipeline projects, which makes it inconvenient to apply external force to the nut and the bolt head at the same time, thereby making it difficult to tighten the pipeline joints.

[0005] To achieve the above purpose, the present invention is implemented by the following technical scheme: a flip-type high-strength pipeline bolt fastener, comprising a screw, an outer wall of the screw is provided with an internal thread, a nut is threadedly connected to the outer wall of the screw, a flange is provided at the lower part of the nut, a flip block is provided at the lower part of the flange, a rotation groove is provided on the outer wall of the screw, the flip block is located inside the rotation groove, the flip block and the rotation groove are both annularly arrayed with the center of the screw, a rotating ring is provided at the lower part of the rotation groove, a fixing hole is provided at the lower part of the flip block, the rotating ring is located in the fixing hole, a first friction tooth is provided on the side of the flip block close to the screw, the first friction tooth is inclined 30 degrees with respect to the side close to the screw, the bottom surface of the flip block is connected to the bottom surface of the rotation groove by a reset device, the corner of the flip block facing the flange is an arc chamfered, the corner of the flip block facing the flange protrudes from the outer wall of the screw, and a gap is left between the side of the flip block close to the screw and the inner wall of the rotation groove.

[0006] Preferably, the reset device is a spring, one end of the spring is fixedly connected to the bottom of the fixing hole, and the other end of the spring is fixedly connected to the inner bottom surface of the spring.

[0007] Preferably, a column cap is provided at one end of the screw away from the internal thread.

[0008] Preferably, a slot is provided at the bottom of the nut, a second mounting hole is provided in the middle of the nut, an internal thread is provided on the inner wall of the second mounting hole, and the slots are arranged in a circular array with the second mounting hole as the center.

[0009] Preferably, a gasket is provided between the nut and the flange, and a second friction tooth is fixedly connected to the side of the gasket close to the nut. The second friction tooth is inclined at -30 degrees with the top surface of the gasket, and the length of the second friction tooth fits the slot. A first mounting hole is opened in the middle of the gasket, and the second friction teeth are arranged in a circular array with the center of the first mounting hole.

[0010] Preferably, a third friction tooth is fixedly connected to the bottom surface of the gasket, the third friction tooth is inclined, the inclination angle is opposite to that of the second friction tooth, the length of the third friction tooth is greater than that of the second friction tooth, and the third friction tooth forms a circular array with the center of the first mounting hole.

[0011] The flip-type high-strength pipeline bolt fastener comprises the following raw materials in parts by weight: 65-97 parts of iron, 1-1.5 parts of chromium, 0.2-0.4 parts of molybdenum, 0.4-0.8 parts of manganese, 0.2-0.4 parts of silicon, 0.05-0.12 parts of vanadium, 0.2-0.4 parts of nickel, and 0.02-0.05 parts of niobium.

[0012] The method for preparing a flip-type high-strength pipeline bolt fastener comprises the following steps:

[0013] S1. Melting: Weigh the raw materials of each component according to the formula, and then control the furnace temperature at 1500-1650 degrees Celsius. First, add iron into the furnace to melt into molten iron, then add molybdenum and chromium, and stir with a graphite stirring rod at the same time. Control the stirring speed at 30-50 revolutions per minute, stir for 15-30 minutes, then add manganese and silicon, continue stirring for 10-20 minutes, then add vanadium, nickel and niobium, and continue stirring for 20-30 minutes after adding vanadium, nickel and niobium to form an alloy solution;

[0014] S2, refining: VD refining is performed on the alloy solution, while argon blowing and stirring are performed, the argon flow rate is controlled at 10-15 liters per minute, and VD refining is continued for 40-80 minutes to form molten steel;

[0015] S3, casting: casting the refined molten steel into an ingot casting mold to form an alloy steel ingot;

[0016] S4, forging: heating the cooled ingot to 1000-1200 degrees Celsius, forging the ingot into a cylindrical screw blank by an air hammer, and controlling the forging ratio between 3-5;

[0017] S5, machining: turning the screw blank by machining;

[0018] S6. Heat treatment: heat the processed screw to 850-950 degrees Celsius through a heater, and then quench it with pure water for 5-15 seconds. After quenching, temper the screw through a heater, and the tempering temperature is controlled at 500-650 degrees Celsius, and the tempering time is controlled at 60-180 minutes;

[0019] S7, surface treatment: clean the screw after heat treatment, put the cleaned screw into zinc liquid for galvanizing, control the temperature of zinc liquid at 430-460 degrees Celsius, control the galvanizing time at 3-10 minutes, and control the galvanizing thickness at 8-12μm;

[0020] S8. Quality inspection: Conduct tensile test, hardness test and impact test on the finished screw to ensure that the yield strength is between 800-1000MPa, the tensile strength is between 1000-1200MPa, the Rockwell hardness is between 30-40, and the impact toughness value is between 40-60J.

[0021] Working principle: After installing the flange at the joint of the pipeline, insert the bolts through the mounting holes of the flange to allow the flip block to pass through the flange, then insert the gasket through the first mounting hole into the end of the bolt away from the column head, and then engage the nut with the thread of the outer wall of the bolt through the second mounting hole, and then apply a rotational force to the nut to make the nut rotate and move toward one side of the flange. When the bottom surface of the nut contacts the top surface of the gasket, continue to rotate the nut so that the flip block moves toward the corner edge of the flange, and then the fixed hole of the flip block rotates outward around the rotating ring until the flip block rotates close to the side of the bolt to fit with the bottom surface of the flange, and continue to rotate the nut until it is tightened.

[0022] The present invention provides a flip-type high-strength pipeline bolt fastener, which has the following beneficial effects:

[0023] 1. In the present invention, the first friction teeth arranged on the outer wall of the flip block can generate a large friction force with the flange after the flip block is opened by the rotating ring. At the same time, when the rotational force is applied to the nut, the reverse force can be obtained through the first friction teeth. Therefore, the tightening work can be completed only by rotating the nut, thereby improving the traditional bolts that require external force to be applied to the nut and the bolt head at the same time to be tightened. However, there are often narrow corners at the bends in pipeline projects, which makes it inconvenient to apply external force to the nut and the bolt head at the same time, thereby causing difficulty in tightening the pipeline joint.

[0024] 2. In the present invention, the second friction teeth arranged on the top of the gasket can fit into the groove at the bottom of the nut, thereby preventing the nut from rotating counterclockwise and causing the nut to loosen without hindering the rotation of the nut. The third friction teeth at the bottom of the gasket can increase the friction with the flange surface, thereby further increasing the anti-loosening effect of the nut.

[0025] 3. In the present invention, by adding vanadium, nickel and niobium to the raw materials of the bolt fasteners, the strength and corrosion resistance of the bolt fasteners can be further improved, thereby preventing the bolt fasteners from being overlooked by liquid in the pipeline fastening scene, thereby enhancing the durability of the bolt fasteners. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the front three-dimensional structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the three-dimensional structure of the flip block of the present invention;

[0028] Figure 3 It is a top view of the three-dimensional structure of the gasket of the present invention;

[0029] Figure 4 It is a bottom-up three-dimensional structural schematic diagram of the gasket of the present invention;

[0030] Figure 5 It is a bottom-up stereoscopic structural schematic diagram of the nut of the present invention;

[0031] Figure 6 It is a schematic diagram of the local cross-sectional structure of the flip block of the present invention;

[0032] Figure 7 It is a schematic diagram of the local structure after the flip block of the present invention is opened.

[0033] Among them, 1. nut; 2. gasket; 3. flange; 4. flip block; 5. screw; 6. column head; 7. fixing hole; 8. first friction tooth; 9. first mounting hole; 10. second friction tooth; 11. third friction tooth; 12. slot; 13. second mounting hole; 14. spring. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1:

[0036] Please refer to the attached Figure 1 -Attached Figure 7 The embodiment of the present invention provides a flip-type high-strength pipeline bolt fastener, including a screw 5, an outer wall of the screw 5 is provided with an internal thread, a nut 1 is threadedly connected to the outer wall of the screw 5, a flange 3 is provided at the lower part of the nut 1, a flip block 4 is provided at the lower part of the flange 3, a rotation groove is provided on the outer wall of the screw 5, the flip block 4 is located inside the rotation groove, the flip block 4 and the rotation groove are both annularly arrayed with the center of the screw 5, a rotating ring is provided at the lower part of the rotation groove, a fixing hole 7 is provided at the lower part of the flip block 4, the rotating ring is located in the fixing hole 7, a first friction tooth 8 is provided on the side of the flip block 4 close to the screw 5, the first friction tooth 8 is inclined 30 degrees to the side close to the screw 5, the bottom surface of the flip block 4 is connected to the bottom surface of the rotation groove through a reset device, the corner of the flip block 4 facing the flange 3 is an arc chamfered shape, the corner of the flip block 4 facing the flange 3 protrudes from the outer wall of the screw 5, and a gap is left between the side of the flip block 4 close to the screw 5 and the inner wall of the rotation groove.

[0037] Specifically, the screw 5 cooperates with other structures to achieve the function of connection and fastening, the nut 1 can rotate and move on the screw 5 to achieve the function of fastening, the flange 3 can connect the pipeline, the flip block 4 can support and fix the flange 3 after rotating with the rotating ring as the center, the rotating groove can be used to place the flip block 4, the fixing hole 7 can fix the flip block 4 inside the rotating groove, so that the flip block 4 can only perform rotational movement, the first friction tooth 8 can increase the friction between the flip block 4 and the flange 3, and the first friction tooth 8 can be tilted 30 degrees by the side close to the screw 5 to achieve the function of clockwise rotation. When the needle turns the nut 1, the flip block 4 and the flange 3 generate a counterclockwise reaction force, so that the tightening work can be completed by only applying a rotating force to the nut 1. The corners of the flip block 4 facing the flange 3 are chamfered in an arc shape, which makes it easier to open the flip block 4 when the flip block 4 is close to the flange 3. The corners of the flip block 4 facing the flange 3 protrude from the outer wall of the screw 5, which makes it easier to open the flip block 4 when the flip block 4 is close to the flange 3. A gap is left between the side of the flip block 4 close to the screw 5 and the inner wall of the rotating groove, so that the screw 5 can be compressed when entering the flange 3, thereby retracting the flip block 4, so that the flange 3 is not obstructed.

[0038] Please see attached Figure 6 -Attached Figure 7 The reset device is a spring 14 , one end of the spring 14 is fixedly connected to the bottom of the fixing hole 7 , and the other end of the spring 14 is fixedly connected to the inner bottom surface of the spring 14 .

[0039] Specifically, the spring 14 can keep the corner of the flip block 4 facing the flange 3 always protruding from the outer wall of the screw 5 when the flip block 4 is not subjected to external pressure.

[0040] Please see attached Figure 1 A column head 6 is provided at one end of the screw rod 5 away from the internal thread.

[0041] Specifically, the column head 6 is in an arc shape, and the screw rod 5 can be easily inserted into other structures through the column head 6.

[0042] Please see attached Figure 5 A slot 12 is provided at the bottom of the nut 1, a second mounting hole 13 is provided in the middle of the nut 1, an inner thread is provided on the inner wall of the second mounting hole 13, and the slot 12 is arranged in a circular array with the second mounting hole 13 as the center.

[0043] Specifically, the locking groove 12 can play a role in locking the second friction tooth 10 .

[0044] Please see attached Figure 1 -Attached Figure 4A gasket 2 is arranged between the nut 1 and the flange 3, and a second friction tooth 10 is fixedly connected to the side of the gasket 2 close to the nut 1. The second friction tooth 10 is inclined at -30 degrees with the top surface of the gasket 2. The length of the second friction tooth 10 matches the slot 12. A first mounting hole 9 is opened in the middle of the gasket 2, and the second friction teeth 10 are arranged in a circular array with the center of the first mounting hole 9 as the center.

[0045] Specifically, the second friction teeth 10 can prevent the nut 1 from loosening counterclockwise after being tightened clockwise, thereby playing an anti-loosening role.

[0046] Please refer to the attached Figure 1 -Attached Figure 4 A third friction tooth 11 is fixedly connected to the bottom surface of the gasket 2. The third friction tooth 11 is inclined, and the inclination angle is opposite to that of the second friction tooth 10. The length of the third friction tooth 11 is greater than that of the second friction tooth 10. The third friction tooth 11 is arranged in a circular array with the center of the first mounting hole 9 as the center.

[0047] Specifically, the third friction teeth 11 can increase the friction force between the flange 3 and the gasket 2 to prevent rotation.

[0048] Example 2: A flip-type high-strength pipeline bolt fastener comprises the following raw materials in parts by weight: 65-97 parts of iron, 1-1.5 parts of chromium, 0.2-0.4 parts of molybdenum, 0.4-0.8 parts of manganese, 0.2-0.4 parts of silicon, 0.05-0.12 parts of vanadium, 0.2-0.4 parts of nickel, and 0.02-0.05 parts of niobium.

[0049] Specifically, iron can provide basic strength and toughness, chromium can enhance the corrosion resistance of bolts, molybdenum can improve the high-temperature strength and toughness of bolts, manganese can remove harmful impurities in steel, silicon can increase the strength and hardness of alloy steel, vanadium can hinder dislocation movement, thereby improving the strength and hardness of alloy steel, nickel can further improve the toughness of alloy steel, and niobium can further improve the strength and toughness of alloy steel bolts.

[0050] Embodiment 3: A method for preparing a flip-type high-strength pipeline bolt fastener, comprising the following steps:

[0051] S1. Melting: Weigh the raw materials of each component according to the formula, and then control the furnace temperature at 1500-1650 degrees Celsius. First, add iron into the furnace to melt into molten iron, then add molybdenum and chromium, and stir with a graphite stirring rod at the same time. Control the stirring speed at 30-50 revolutions per minute, stir for 15-30 minutes, then add manganese and silicon, continue stirring for 10-20 minutes, then add vanadium, nickel and niobium, and continue stirring for 20-30 minutes after adding vanadium, nickel and niobium to form an alloy solution;

[0052] S2, refining: VD refining is performed on the alloy solution, while argon blowing and stirring are performed, the argon flow rate is controlled at 10-15 liters per minute, and VD refining is continued for 40-80 minutes to form molten steel;

[0053] S3, casting: casting the refined molten steel into an ingot casting mold to form an alloy steel ingot;

[0054] S4, forging: heating the cooled ingot to 1000-1200 degrees Celsius, forging the ingot into a cylindrical screw 5 blank by an air hammer, and controlling the forging ratio between 3-5;

[0055] S5, machining: turning the screw 5 blank by machining;

[0056] S6, heat treatment: the processed screw 5 is heated to 850-950 degrees Celsius by a heater, and then quenched by pure water for 5-15 seconds. After quenching, the bolt is tempered by a heater, and the tempering temperature is controlled at 500-650 degrees Celsius, and the tempering time is controlled at 60-180 minutes;

[0057] S7, surface treatment: cleaning the screw 5 after heat treatment, placing the cleaned screw 5 into zinc solution for galvanizing, controlling the temperature of the zinc solution to 430-460 degrees Celsius, the galvanizing time to 3-10 minutes, and the galvanizing thickness to 8-12 μm;

[0058] S8. Quality inspection: Perform tensile test, hardness test and impact test on the finished screw 5 to ensure that the yield strength is between 800-1000MPa, the tensile strength is between 1000-1200MPa, the Rockwell hardness is between 30-40, and the impact toughness value is between 40-60J.

[0059] Specifically, by controlling the furnace temperature at 1500-1650 degrees Celsius, it is beneficial to fully fuse various elements, and it is possible to ensure that the molten steel has good fluidity, which is convenient for subsequent refining and casting operations. VD refining can promote the uniformity of the composition and temperature of the molten steel, and remove inclusions and harmful gases in the molten steel. By heating the cooled ingot to 1000-1200 degrees Celsius, the alloy steel can have good plasticity and forgeability. By controlling the forging ratio between 3-5, the organization and performance of the alloy steel can be improved, and the comprehensive mechanical properties of the bolt can be improved. By quenching, the alloy steel can obtain a martensitic organization, which significantly improves the hardness and strength of the bolt. By tempering, the quenching internal stress can be eliminated, the toughness and plasticity of the bolt can be improved, and the bolt can obtain good comprehensive mechanical properties. By controlling the temperature of the zinc liquid at 430-460 degrees Celsius, a uniform and dense zinc coating can be formed on the surface of the bolt.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A flip-type high-strength pipeline bolt fastener, comprising a bolt (5), characterized in that: The outer wall of the bolt (5) is provided with an internal thread, the outer wall of the bolt (5) is threadedly connected with a nut (1), a flange (3) is provided at the bottom of the nut (1), a flip block (4) is provided at the bottom of the flange (3), a rotation groove is provided on the outer wall of the bolt (5), the flip block (4) is located inside the rotation groove, the flip block (4) and the rotation groove are both arranged in a circular array with the center of the bolt (5), a rotation ring is provided at the bottom of the rotation groove, a fixing hole (7) is provided at the bottom of the flip block (4), and the rotation ring is located at In the fixing hole (7), the side of the flip block (4) close to the bolt (5) is provided with a first friction tooth (8), the first friction tooth (8) is inclined at 30 degrees with respect to the side close to the bolt (5), the bottom surface of the flip block (4) is connected to the bottom surface of the rotating groove via a reset device, the corner of the flip block (4) facing the flange (3) is in an arc chamfered shape, the corner of the flip block (4) facing the flange (3) protrudes from the outer wall of the bolt (5), and a gap is left between the side of the flip block (4) close to the bolt (5) and the inner wall of the rotating groove.

2. The flip-over high-strength pipeline bolt fastener according to claim 1 is characterized in that: The reset device is a spring (14), one end of the spring (14) is fixedly connected to the bottom of the fixing hole (7), and the other end of the spring (14) is fixedly connected to the inner bottom surface of the spring (14).

3. The flip-over high-strength pipeline bolt fastener according to claim 1 is characterized in that: A stud (6) is provided at one end of the bolt (5) away from the internal thread.

4. The flip-over high-strength pipeline bolt fastener according to claim 1, characterized in that: The bottom of the nut (1) is provided with a slot (12), the middle of the nut (1) is provided with a second mounting hole (13), the inner wall of the second mounting hole (13) is provided with an internal thread, and the slots (12) are arranged in a circular array with the second mounting hole (13) as the center.

5. The flip-over high-strength pipeline bolt fastener according to claim 4 is characterized in that: A gasket (2) is arranged between the nut (1) and the flange (3); a second friction tooth (10) is fixedly connected to a side of the gasket (2) close to the nut (1); the second friction tooth (10) is inclined at -30 degrees with the top surface of the gasket (2); the length of the second friction tooth (10) matches the slot (12); a first mounting hole (9) is opened in the middle of the gasket (2); and the second friction teeth (10) are arranged in a circular array with the center of the first mounting hole (9) being the center.

6. The flip-over high-strength pipeline bolt fastener according to claim 5, characterized in that: A third friction tooth (11) is fixedly connected to the bottom surface of the gasket (2); the third friction tooth (11) is inclined, and the inclination angle is opposite to that of the second friction tooth (10); the length of the third friction tooth (11) is greater than that of the second friction tooth (10); and the third friction teeth (11) form a circular array with the center of the first mounting hole (9).

7. Flip-type high-strength pipeline bolt fastener, characterized in that: The invention comprises the following raw materials in parts by weight: 65-97 parts of iron, 1-1.5 parts of chromium, 0.2-0.4 parts of molybdenum, 0.4-0.8 parts of manganese, 0.2-0.4 parts of silicon, 0.05-0.12 parts of vanadium, 0.2-0.4 parts of nickel and 0.02-0.05 parts of niobium.

8. The method for preparing the flip-over high-strength pipeline bolt fastener according to claim 7 comprises the following steps: S1. Melting: Weigh the raw materials of each component according to the formula, and then control the furnace temperature at 1500-1650 degrees Celsius. First, add iron into the furnace to melt into molten iron, then add molybdenum and chromium, and stir with a graphite stirring rod at the same time. Control the stirring speed at 30-50 revolutions per minute, stir for 15-30 minutes, then add manganese and silicon, continue stirring for 10-20 minutes, then add vanadium, nickel and niobium, and continue stirring for 20-30 minutes after adding vanadium, nickel and niobium to form an alloy solution; S2, refining: VD refining is performed on the alloy solution, while argon blowing and stirring are performed, the argon flow rate is controlled at 10-15 liters per minute, and VD refining is continued for 40-80 minutes to form molten steel; S3, casting: casting the refined molten steel into an ingot casting mold to form an alloy steel ingot; S4, forging: heating the cooled ingot to 1000-1200 degrees Celsius, and forging the ingot into a columnar bolt (5) blank by an air hammer, with the forging ratio controlled between 3-5; S5, machining: turning the bolt (5) blank by machining; S6, heat treatment: heating the processed bolt (5) to 850-950 degrees Celsius through a heater, and then quenching it with pure water for 5-15 seconds. After quenching, tempering the bolt through a heater, the tempering temperature is controlled at 500-650 degrees Celsius, and the tempering time is controlled at 60-180 minutes; S7, surface treatment: cleaning the bolts (5) after heat treatment, placing the cleaned bolts (5) in zinc solution for galvanizing, controlling the temperature of the zinc solution to 430-460 degrees Celsius, the galvanizing time to 3-10 minutes, and the galvanizing thickness to 8-12 μm; S8. Quality inspection: Conduct tensile test, hardness test and impact test on the finished bolts (5) to ensure that the yield strength is between 800-1000MPa, the tensile strength is between 1000-1200MPa, the Rockwell hardness is between 30-40, and the impact toughness value is between 40-60J.

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