Spiral lifting structure and durability optimization process thereof

Abstract

The invention belongs to the technical field of machine manufacturing and material processing, and particularly relates to a spiral lifting structure and a durability optimization process thereof.The spiral lifting structure comprises a spiral steel belt and a spiral steel column meshed with the spiral steel belt, a plurality of spiral teeth are arranged at the edge of the outer surface of the spiral steel belt in the direction of the spiral steel belt at equal intervals, and oblique angles are symmetrically arranged on the two sides of each spiral tooth; the spiral steel column is a hollow cylinder, the spiral steel belt is arranged in the spiral steel column in a meshing mode, and tooth grooves meshed with the spiral teeth in the reverse direction are formed in the inner surface of the spiral steel column. The height of the spiral teeth is 30 mm, the thickness of the spiral teeth is 15 mm, and the inclination angle of the oblique angle is 15 degrees. The material grain structure can be optimized through high-frequency induction quenching and composite tempering, the ductility of the steel strip is improved, shot peening strengthening is adopted, the fatigue strength of the steel strip is improved, the possibility that the steel strip is damaged or falls off in a severe environment is reduced in combination with a galvanization process, and the service life of the steel strip is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical manufacturing and material processing, and particularly relates to a spiral lifting structure and a durability optimization process thereof. Background Art

[0002] With the development of the precision machine tool industry, spiral steel strips are widely used in CNC machine tools and machining centers. They offer protection against dust, chips, and coolant, effectively maintaining machine tool precision and extending service life. Made from heat-treated spring steel strip, they exhibit excellent elasticity, flexibility, and rigidity, effectively preventing external contamination. Heat treatment of steel strips is a metalworking process that achieves desired properties through heating, holding, and cooling, including annealing, normalizing, and tempering.

[0003] Problems with existing technologies: The existing steel strip heat treatment process has the problems of uneven heating, large temperature fluctuations, uneven performance, extensive quenching and cooling, insufficient hardness or large deformation, lack of long and thin wall adaptation, easy bending, poor precision, and many surface defects. What is particularly prominent is that the traditional single quenching process is also prone to grain coarsening, which reduces the fatigue life of the spiral steel strip. Under heavy load conditions, the steel strip is more prone to bending and deformation, resulting in equipment failure and increased replacement costs. Summary of the Invention

[0004] The purpose of the present invention is to provide a spiral lifting structure and its durability optimization process, which can optimize the material grain structure through high-frequency induction quenching and composite tempering, improve the ductility of the steel strip, adopt shot peening to improve the fatigue strength of the steel strip, and combine with the galvanizing process to reduce the possibility of breakage or falling off of the steel strip in harsh environments, thereby extending the service life of the steel strip.

[0005] The technical solutions adopted by the present invention are as follows: A spiral lifting structure, comprising a spiral steel belt and a spiral steel column meshed therewith, wherein the outer surface edge of the spiral steel belt is provided with a plurality of spiral teeth equidistantly arranged along its own direction, and the spiral teeth are symmetrically provided with bevel angles on both sides; The spiral steel column is a hollow cylinder, the spiral steel belt is arranged inside the spiral steel column in an engageable manner, and the inner surface of the spiral steel column is provided with tooth grooves that engage in reverse with the spiral teeth.

[0006] The height of the spiral teeth is 30 mm, the thickness is 15 mm, and the inclination angle of the bevel is 15°.

[0007] A durability optimization process for a spiral lifting structure, comprising a spiral steel strip heat treatment process and a spiral steel column heat treatment process; The steps of the heat treatment process of the spiral steel strip are as follows: Step S1, material selection, selecting high silicon manganese spring steel strip as raw material; Step S2, pretreatment, heating the steel strip to below 700±10°C in an annealing furnace, keeping the temperature for 2-4 hours, performing spheroidizing annealing, and then slowly cooling to room temperature at a rate of ≤30°C / h to obtain spherical pearlite. After annealing, the surface of the steel strip is inspected; Step S3, cold rolling forming, using multiple cold rolling passes to change the shape of the spring steel strip, and keeping it at 250-300°C for 30 minutes after cold rolling; Step S4, quenching, uses a combination of induction heating and a protective atmosphere furnace to perform quenching treatment. First, the steel strip surface is rapidly heated to 850°C by high-frequency induction. The steel strip is then transferred to a protective atmosphere furnace and the core temperature is uniformly brought to 880°C. After the insulation is completed, the steel strip is placed in a 300°C nitrate bath for 30 minutes and then air-cooled to room temperature. Step S5, medium temperature tempering, the spiral steel strip is immediately subjected to primary tempering after quenching, then oil cooling, followed by secondary tempering, and finally water cooling; Step S6, shot peening, wherein the surface of the heat-treated spiral steel strip is struck by metal shots at high speed; Step S7, relaxation treatment, subjecting the spiral steel strip to a heat-pressure relaxation treatment at an environment 20°C higher than the working temperature for 2-8 hours; Step S8, galvanizing treatment, using a cyanide-free alkaline galvanizing process to form a 20-25 μm coating on the surface of the spiral steel strip.

[0008] In step S3, during the cold rolling process, the total deformation is controlled to be 50%-60%.

[0009] In step S4, the holding time is extended to 3 min / mm, and the total holding time is 70 minutes.

[0010] In step S5, the first tempering is carried out at a temperature of 450° C. for 2 hours, and the second tempering is carried out at a temperature of 400° C. for 1.5 hours.

[0011] In step S6, during shot peening, metal shots with a diameter of 0.3-0.7 mm are used at a shot peening speed of 60-80 m / s, using a centrifugal shot peening machine to achieve a coverage rate of ≥200%, and the steel strip surface is struck by high-speed projectiles.

[0012] The heat treatment process steps of the spiral steel column are as follows: Step R1, material selection, select medium carbon alloy steel as raw material; Step R2, normalizing treatment, heating the carbon alloy steel to 850-900°C, holding the steel at this temperature for 60±5 minutes (calculated as 1.5 minutes / mm based on the diameter), and air cooling the steel to room temperature; further air cooling the steel to room temperature to obtain uniform fine-flaked pearlite and ferrite; Step R3, hot forming processing, heating the pretreated alloy steel to 1000-1100°C, forming it on a plate rolling machine, and then using hot working to break carbides; Step R4, annealing, heating the formed spiral steel column to 850-900°C in a furnace at a heating rate of 10-15°C / min and holding for 60±5min; then cooling it to 730±10°C and holding it isothermally for 120±5min; then cooling it to below 500±10°C in the furnace and air cooling it out of the furnace; Step R5, quenching and tempering treatment, first perform quenching treatment, heat the spiral steel column, heat it to 850-870℃ with the furnace, keep it warm for 30 minutes, heat it to 900℃ and keep it warm for 90 minutes, then water cool or oil cool it to obtain high-strength martensite; Then, three tempering treatments are carried out, and three groups of oils are preheated to 495℃-500℃, 245℃-255℃ and 25℃-35℃ respectively; the spiral steel column is immersed in the three groups of oils at 495-500℃, 245-255℃ and 25-35℃ in sequence, with each stage kept at this temperature for 10-15 minutes. After the oil is cooled to room temperature, the next tempering stage is carried out; Step R6, surface strengthening, the spiral steel column is subjected to nitrocarburizing in a 540°C pit furnace. After keeping the temperature for 6 hours, the inner and outer sides of the spiral steel column are subjected to gradient shot peening with cast steel shots and ceramic shots respectively.

[0013] In step R6, the gas flow ratio of nitrocarburizing is ammonia:propane=3:1, and the pressure in the furnace is 50-100 Pa.

[0014] In step R6, 0.6-1.0 mm cast steel shots are used for inner shot peening, with a coverage rate of ≥300% and a shot peening intensity of 0.35-0.45 N; 0.3-0.5 mm ceramic shots are used for outer shot peening, with a coverage rate of ≥200% and a shot peening intensity of 0.12-0.18 N.

[0015] The technical effects achieved by the present invention are: In the heat treatment process, the present invention optimizes the material grain structure through high-frequency induction quenching and composite tempering to improve the ductility of the steel strip, adopts shot peening to improve the fatigue strength of the steel strip, and combines the galvanizing process to reduce the possibility of damage or falling off of the steel strip in harsh environments. The mechanical properties, dimensional accuracy and surface quality of the spiral steel strip are significantly improved: the uniformity of strength and hardness is improved, the fatigue resistance is enhanced, and the problem of bending and deformation of the spiral steel strip under heavy load and high-frequency reciprocating motion is reduced, thereby improving the service life of the spiral steel strip.

[0016] The present invention optimizes the material grain structure through post-forging graded annealing cooling and three-stage tempering insulation to improve the strength of the steel column, and combines nitrogen and carbon co-diffusion and gradient shot peening to enhance wear resistance and bite properties; the friction coefficient of the galvanized layer of the steel strip matches the nitrided layer of the steel column to reduce motion wear; gradient shot peening and uniform shot peening form complementary stress distributions to enhance the overall fatigue resistance of the system; the spiral steel column has a thickness of 20 mm, which can meet certain load-bearing bending moment requirements and effectively control material usage and its own weight; at the same time, when combined with the spiral steel strip, this thickness can ensure that the gear teeth and the steel column have appropriate contact depth and bonding strength, thereby ensuring the reliability of motion transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the spiral lifting structure of the present invention; Figure 2 Schematic diagram of the spiral steel belt structure of the present invention; Figure 3 This is a process flow chart of heat treatment of spiral steel strips according to the present invention; Figure 4 This is a process flow chart of the heat treatment of spiral steel columns of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following examples. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection of the present invention.

[0019] like Figure 1-Figure 2 As shown, a spiral lifting structure includes a spiral steel belt 1 and a spiral steel column 2 meshing therewith. The diameter of the spiral steel belt 1 is set to 300 mm. A plurality of spiral teeth 3 are equidistantly arranged along the outer edge of the spiral steel belt 1 along its own direction. Bevels are symmetrically arranged on both sides of the spiral teeth 3. The height of the spiral teeth 3 is 30 mm, the thickness is 15 mm, and the inclination angle of the bevel is 15°. The spiral steel column 2 is a hollow cylinder with a thickness of 20 mm. The spiral steel belt 1 is arranged inside the spiral steel column 2 in a meshing manner. The inner surface of the spiral steel column 2 is provided with tooth grooves that mesh in the opposite direction with the spiral teeth 3. The material of the spiral steel belt 1 is spring steel, and the material of the spiral steel column 2 is medium carbon alloy steel.

[0020] According to the above structure, the diameter of the spiral steel belt 1 is set to 300mm, which can provide a larger contact area, help to disperse the load, reduce the pressure per unit area, reduce its wear, and also improve the stability of the equipment and reduce shaking; The height of the spiral tooth 3 is designed to be 30mm and the thickness is 15mm. It is buffered by 15° bevels on both sides. According to the bending strength formula σF=KFtYF / bm, a larger tooth height can reduce the tooth form factor YF, which significantly reduces the bending stress at the root of the spiral tooth 3 and effectively resists the risk of tooth root fracture under heavy load. The thickness of 15mm is calculated by the contact strength formula σ H =√2KF t (u±1) / πbud1sin 2 α Ensures that the contact area has sufficient stress bearing capacity to avoid surface crushing or excessive wear due to insufficient thickness; The 15° bevel angle on both sides of the helical teeth 3 introduces a helix angle effect, making the load transfer process smoother when the helical teeth 3 engage, improving the overlap and reducing the impact load, significantly improving the vibration and noise problems during high-frequency expansion and contraction. In addition, when the steel belt is compressed to 0.5m in the storage state, the guiding effect of the bevel angle can significantly reduce the geometric interference between the helical teeth 3 and the tooth grooves, reducing the meshing resistance and ensuring the flexibility of the movement mechanism. From the perspective of processing feasibility, the 15° bevel angle, 30mm height, and 15mm thickness form a reasonable geometric ratio. This not only ensures that the tooth top thickness is ≥5mm, avoiding strength defects caused by excessive tooth top tip during processing, but also meets the process requirements of the cutting tool, reducing processing difficulty and material waste. The thickness of the spiral steel column 2 is set to 20mm, which can effectively control the material usage and its own weight while meeting certain load-bearing bending moment requirements; at the same time, when combined with the spiral steel belt 1, this thickness can ensure that the spiral teeth 3 and the spiral steel column 2 have appropriate contact depth and bonding strength, ensuring the reliability of motion transmission; during the transmission process, the tooth shape design of the gear teeth conforms to the standard tooth shape, which can ensure a smooth transmission ratio and reduce impact and vibration. At the same time, the characteristics of the spiral structure itself also contribute to smooth movement. During the rising process, the continuous movement of the spiral can make the load rise evenly and avoid unstable phenomena such as jumping; the spiral steel belt 1 is combined with the spiral steel column 2 through the spiral 3 to promote the movement of the steel column. This method is similar to the principle of gear transmission; the meshing of the gear teeth can achieve precise motion transmission, ensuring that the rotation of the spiral steel belt 1 is effectively converted into the linear upward movement of the steel column.

[0021] like Figure 3 As shown, a durability optimization process for a spiral lifting structure includes a heat treatment process for a spiral steel belt 1 and a heat treatment process for a spiral steel column 2; The heat treatment process steps of the spiral steel strip 1 are as follows: Step S1, material selection, selecting high silicon-manganese spring steel strip as raw material, silicon-manganese steel has high yield strength, tempering resistance and fatigue resistance; Step S2, pretreatment, heating the steel strip to below 700±10°C in an annealing furnace, performing spheroidizing annealing, holding the temperature for 2-4 hours, and slowly cooling to room temperature at a rate of ≤30°C / h to obtain spherical pearlite with a hardness of HBS180. Then, after annealing, inspect the surface of the steel strip to ensure that there are no cracks or decarburized layers on the surface; Step S3, cold rolling, using multiple cold rolling passes to change the shape of the spring steel strip and shape it into a spiral steel strip 1. The total deformation is controlled at 50%-60% to ensure uniform strengthening. After cold rolling, it is kept at 250-300°C for 30 minutes to eliminate processing stress and stabilize the size. Step S4, quenching, using a combination of induction heating and a protective atmosphere furnace for quenching treatment. First, the steel strip surface is rapidly heated to 850°C by high-frequency induction. The steel strip is then transferred to a protective atmosphere furnace and the core temperature is brought to 880°C. The holding time is extended to 3 min / mm, and the total holding time is 70 minutes. After the holding period, the steel strip is placed in a 300°C nitrate bath for 30 minutes and then air-cooled to room temperature. Step S5, medium-temperature tempering: the spiral steel strip 1 is immediately subjected to primary tempering after quenching, and is kept at 450°C for 2 hours, followed by oil cooling to eliminate quenching stress, and then to secondary tempering, and is kept at 400°C for 1.5 hours, and finally water cooling to further stabilize the structure; Step S6, shot peening, using metal shots with a diameter of 0.3-0.7 mm at a shot peening speed of 60-80 m / s on the heat-treated spiral steel strip 1, using a centrifugal shot peening machine to achieve a coverage rate of ≥ 200%, and striking the surface of the steel strip at high speed to put the surface in a compressive stress state, thereby improving the fatigue strength and service life of the steel strip; Step S7, relaxation treatment, using hot pressing relaxation treatment, performing strong pressing for 2-8 hours at a constant temperature 20° C. higher than the working temperature of the spiral steel strip 1 to reduce stress relaxation of the spiral steel strip 1; Step S8, galvanizing treatment, finally, the spiral steel strip 1 is electroplated using a cyanide-free alkaline galvanizing process, with a coating thickness of 20-25 μm, to avoid high temperature affecting the early heat treatment performance and improve the corrosion resistance of the steel strip.

[0022] Example 1 Step S1, material selection, select high silicon manganese spring steel strip as raw material, Step S2, pretreatment, placing the steel strip in an annealing furnace, heating it to 690°C, performing spheroidizing annealing, holding the temperature for 2 hours, and then slowly cooling it to room temperature at a rate of 25°C / h to obtain spherical pearlite, the hardness of which is HBS180. The surface of the steel strip is tested, and no cracks or decarburized layer are found on the surface; Step S3, cold rolling forming, using multiple cold rolling passes to shape the spring steel strip into a spiral steel strip 1, with the total deformation controlled at 55% to ensure uniform strengthening; after cold rolling, the steel strip is kept at 270°C for 30 minutes to eliminate processing stress and stabilize the size; Step S4, quenching, uses a combination of induction heating and a protective atmosphere furnace for quenching treatment; first, the steel strip surface is rapidly heated to 850°C by high-frequency induction, and then the steel strip is transferred to a protective atmosphere furnace and the core temperature is brought to 880°C. Since the steel strip thickness is 23mm, the holding time is 3min / mm×23mm=69min, and the actual total holding time is 70 minutes. After the holding period, the steel strip is placed in a 300°C nitrate bath for 30 minutes of isothermal heating, and then air-cooled to room temperature; Step S5, medium-temperature tempering: immediately after quenching, perform primary tempering at 450°C for 2 hours, then oil-cool to eliminate quenching stress; then perform secondary tempering at 400°C for 1.5 hours, and finally water-cool to further stabilize the structure; Step S6, shot peening, using metal projectiles with a diameter of 0.5 mm and a shot peening speed of 70 m / s, using a centrifugal shot peening machine to shot peen the heat-treated spiral steel strip 1 to achieve a coverage rate of 200%. The high-speed projectiles hit the surface of the steel strip, causing the surface to be in a compressive stress state, thereby improving the fatigue strength and service life of the steel strip; Step S7, relaxation treatment: assuming that the working temperature of the spiral steel strip 1 is 100° C., strong pressing is performed at a constant temperature of 120° C. for 4 hours to reduce stress relaxation of the spiral steel strip 1; Step S8, zinc plating treatment, adopts cyanide-free alkaline zinc plating process to electroplate the spiral steel strip 1, and the coating thickness is 22 μm.

[0023] Example 2 Step S1, material selection, also selects high silicon manganese spring steel strip as the raw material; Step S2, pretreatment, heating the steel strip to 700°C, performing spheroidizing annealing, keeping the temperature for 3 hours, and slowly cooling to room temperature at a rate of 30°C / h to obtain spherical pearlite with a hardness of HBS180. The surface inspection shows no cracks or decarburized layer. Step S3, cold rolling forming, multiple cold rolling passes are performed to shape the steel strip into a spiral steel strip 1, with the total deformation controlled at 50%. After cold rolling, the steel strip is kept at 250° C. for 30 minutes to eliminate processing stress and stabilize the size; Step S4, quenching: After high-frequency induction heating of the steel strip surface to 850°C, the strip is transferred to a protective atmosphere furnace and the core temperature is uniformly raised to 880°C. The thickness of the steel strip is 24 mm, and the holding time is 3 min / mm × 24 mm = 72 min, with an actual total holding time of 70 minutes. The strip is then kept at this temperature in a 300°C nitrate bath for 30 minutes and air-cooled to room temperature. Step S5, medium temperature tempering, first tempering at 450°C for 2 hours with oil cooling, second tempering at 400°C for 1.5 hours with water cooling; Step S6, shot peening, using metal shots with a diameter of 0.3 mm, a shot peening speed of 60 m / s, and a centrifugal shot peening machine to achieve a coverage rate of 210%, to shot peen the surface of the steel strip to put it in a compressive stress state; Step S7, relaxation treatment: if the working temperature of the spiral steel strip 1 is 110°C, then it is subjected to strong pressing at a constant temperature of 130°C for 6 hours to reduce stress relaxation; Step S8, galvanizing treatment, cyanide-free alkaline galvanizing process, the coating thickness is 20 μm, to improve the corrosion resistance of the steel strip.

[0024] Example 3 Step S1, material selection, the raw materials are the same as those in Example 1; Step S2, pretreatment, heating the steel strip to 695°C, spheroidizing annealing for 4 hours, and slowly cooling to room temperature at a rate of 20°C / h to obtain spherical pearlite that meets the requirements, and the surface inspection is qualified; Step S3, cold rolling forming, the total deformation of the cold rolling forming is controlled at 60%, and after cold rolling, the temperature is kept at 300°C for 30 minutes to eliminate stress and stabilize the size; Step S4, quenching, after induction heating the surface to 850°C, the core temperature is uniformly heated to 880°C, the thickness of the steel strip is 23mm, and the temperature is kept at this temperature for 70 minutes, and then the temperature is kept in a nitrate bath for 30 minutes and then air-cooled; Step S5, medium temperature tempering, the tempering treatment is the same as in Example 1; Step S6, shot peening, using metal shot with a diameter of 0.7 mm, a shot peening speed of 80 m / s, and a centrifugal shot peening machine to achieve a coverage rate of 220%, to strengthen the surface of the steel strip; Step S7, relaxation treatment: when the working temperature of the spiral steel strip 1 is 90°C, it is subjected to strong pressing at a constant temperature of 110°C for 8 hours to reduce stress relaxation; Step S8: galvanizing treatment, using a cyanide-free alkaline galvanizing process with a coating thickness of 25 μm, to improve the corrosion resistance of the steel strip.

[0025] In summary, in the heat treatment process, high-frequency induction quenching and composite tempering are used to optimize the material grain structure, improve the ductility of the spiral steel strip 1, and shot peening is used to improve the fatigue strength of the spiral steel strip 1. Combined with the galvanizing process, the possibility of damage or falling off of the spiral steel strip 1 in harsh environments is reduced, and the service life of the spiral steel strip 1 is extended. like Figure 4 As shown, the heat treatment process steps of the spiral steel column 2 are as follows: Step R1, material selection, choose medium carbon alloy steel as raw material, which has high hardenability and tempering resistance stability, suitable for high strength requirements; Step R2, normalizing treatment, heating the carbon alloy steel to 850-900°C, holding for 60±5 minutes (calculated as 1.5 minutes / mm based on diameter), and air cooling to room temperature; Air cooling to room temperature obtains uniform fine-flaked pearlite and ferrite, with hardness controlled at HB200-250, improving cutting performance and refining original grains; Step R3, hot forming processing, heating the pretreated alloy steel to 1000-1100℃, forming it on a press or plate rolling machine, controlling the deformation amount to ≥50%, and through dynamic recrystallization during the hot working process, the carbide particle size is broken from the original 5-8μm to 2-3μm, and the streamline distribution is arranged along the spiral generatrix direction to ≥85%, thereby improving the streamline distribution; Step R4, annealing, heating the formed spiral steel column 2 to 850-900°C in a furnace at a heating rate of 10-15°C / min and holding for 60±5min; then cooling it to 730±10°C and holding it isothermally for 120±5min; then cooling it to below 500±10°C in the furnace and air cooling it out of the furnace; Step R5, quenching and tempering treatment, first perform quenching treatment, heat the spiral steel column 2, raise the temperature to 850-870℃ with the furnace, keep it warm for 30 minutes, raise the temperature to 900℃ and keep it warm for 90 minutes, then water cool or oil cool it to obtain high-strength martensite; Then, three tempering treatments are performed, and three groups of oils are preheated to 495℃-500℃, 245℃-255℃ and 25℃-35℃ respectively; the spiral steel column 2 is immersed in the three groups of oils at 495-500℃, 245-255℃ and 25-35℃ in sequence, with each stage being kept warm for 10-15 minutes. After the oil is cooled to room temperature, the next stage of tempering is performed; Step R6, surface strengthening, the spiral steel column 2 is subjected to nitrogen and carbon co-penetration in a 540°C well furnace, the gas flow ratio of nitrogen and carbon co-penetration is ammonia: propane = 3:1, the pressure in the furnace is 50-100Pa, and after keeping warm for 6 hours, the wear resistance and bite resistance are improved; the inner and outer sides of the spiral steel column 2 are respectively subjected to gradient shot peening of cast steel shots and ceramic shots, and the inner side shot peening uses 0.6-1.0mm cast steel shots with a coverage rate of ≥300% and a shot peening intensity of 0.35-0.45N to strengthen the inner layer; the outer layer shot peening uses 0.3-0.5mm ceramic shots with a coverage rate of ≥200% and a shot peening intensity of 0.12-0.18N to strengthen the outer layer.

[0026] Example 4 Step R1, material selection, choose medium carbon alloy steel; Step R2, normalizing treatment, heating to 860℃, holding time calculated based on diameter is 50×1.5=75min, air cooling to room temperature, obtaining hardness HB220, uniform fine lamellar pearlite and ferrite, good cutting performance, and refined original grains; Step R3, hot forming processing, heating to 1050 ° C, forming on a press, controlling the deformation to 60%, crushing the carbide particles to 2.5 μm, and the degree of arrangement of the streamline distribution along the spiral generatrix to 88%; Step R4, annealing, heating to 860°C with a heating rate of 12°C / min, holding for 65 minutes; cooling to 730°C with the furnace, holding isothermal for 125 minutes; then cooling to below 500°C with the furnace, and air cooling out of the furnace; Step R5, quenching and tempering treatment, during quenching, the temperature is raised to 860℃ with the furnace, kept at this temperature for 30 minutes, then raised to 900℃ and kept at this temperature for 90 minutes, and water-cooled to obtain high-strength martensite; three tempering, the oil preheating temperature is 498℃, 250℃, and 30℃ respectively, and the oil is immersed in this temperature for 12 minutes in sequence, and then cooled to room temperature; Step R6, surface strengthening, nitrocarburizing in a pit furnace at 540°C, with a gas flow ratio of ammonia to propane = 3:1, a furnace pressure of 80 Pa, and holding for 6 hours; the inner layer is shot peened with 0.8 mm cast steel shot, with a coverage rate of 350% and a shot peening intensity of 0.4 N; the outer layer is shot peened with 0.4 mm ceramic shot, with a coverage rate of 250% and a shot peening intensity of 0.15 N; Performance indicators: After testing, the strength of the spiral steel column 2 reaches 1200MPa, the wear resistance is improved by 30% compared with the traditional process, and the dimensional stability is good. Example 5 Step R1, material selection, choose medium carbon alloy steel; Step R2, normalizing treatment, heating to 880℃, holding time 80×1.5=120min, air cooling to room temperature, hardness HB230, cutting performance improvement, grain refinement; Step R3, hot forming processing, heating to 1100 ° C, forming on a plate rolling machine, deformation amount 55%, carbide particle size crushing to 2.2 μm, streamline arrangement degree 86%; Step R4, annealing, heating to 880°C with a heating rate of 15°C / min, holding for 70 minutes; cooling to 740°C, isothermal holding for 130 minutes; cooling to 490°C, and air cooling out of the furnace; Step R5, quenching and tempering treatment, quenching temperature is raised to 870℃, kept at this temperature for 30 minutes, then heated to 900℃ and kept at this temperature for 90 minutes, and oil cooling is adopted; the three tempering oil temperatures are 500℃, 255℃ and 35℃ respectively, and each temperature is kept at this temperature for 15 minutes; Step R6, surface strengthening, nitrocarburizing parameters are the same as in Example 1, the inner layer uses 1.0 mm cast steel shot, coverage rate 300%, shot peening intensity 0.45 N; the outer layer uses 0.5 mm ceramic shot, coverage rate 200%, shot peening intensity 0.18 N; Performance indicators: Strength reaches 1150MPa, wear resistance is improved by 25%, and dimensional stability meets high load requirements. Example 6 Step R1, material selection, choose medium carbon alloy steel; Step R2, normalizing treatment, heating to 850℃, holding time 30×1.5=45min, air cooling to room temperature, hardness HB200, good cutting performance; Step R3, hot forming processing, heating to 1000°C, forming deformation of 50%, carbide particles crushed to 3μm, and streamline arrangement of 85%; Step R4, annealing, heating to 850°C with a heating rate of 10°C / min, holding for 55 minutes; cooling to 720°C, isothermal holding for 115 minutes; cooling to 510°C, and air cooling out of the furnace; Step R5, quenching and tempering treatment, quenching temperature is raised to 850℃, kept warm for 30 minutes, heated to 900℃ and kept warm for 90 minutes, and water-cooled; the three tempering oil temperatures are 495℃, 245℃, and 25℃ respectively, and each is kept warm for 10 minutes.

[0027] Step R6, surface strengthening, nitrocarburizing parameters are the same as in Example 1, the inner layer uses 0.6mm cast steel shot, coverage rate 300%, shot peening intensity 0.35N; the outer layer uses 0.3mm ceramic shot, coverage rate 200%, shot peening intensity 0.12N; Performance indicators: Strength reaches 1250MPa, wear resistance increased by 35%, and dimensional stability is excellent.

[0028] In summary, carbon alloy steel is selected, which undergoes double-stage tempering and nitrocarburizing to achieve both high strength and wear resistance. Combined with gradient shot peening, it can effectively improve dimensional stability and is suitable for high-load static support. The material grain structure is optimized through post-forging graded annealing cooling, three-stage tempering and insulation to improve the strength of the steel column. Combined with nitrocarburizing and gradient shot peening, it can improve wear resistance and bite properties.

[0029] The foregoing is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained herein shall, unless otherwise specified or limited, be implemented in accordance with conventional means in the art.

Claims

1. A spiral lifting structure, characterized in that: It comprises a spiral steel belt (1) and a spiral steel column (2) meshed therewith, wherein a plurality of spiral teeth (3) are arranged at equal intervals along the outer surface edge of the spiral steel belt (1), and the spiral teeth (3) are symmetrically provided with bevel angles on both sides; The spiral steel column (2) is a hollow cylinder, the spiral steel belt (1) is arranged inside the spiral steel column (2) in a meshing manner, and the inner surface of the spiral steel column (2) is provided with tooth grooves that mesh in the opposite direction with the spiral teeth (3).

2. A spiral lifting structure according to claim 1, characterized in that: The height of the spiral teeth (3) is 30 mm, the thickness is 15 mm, and the inclination angle of the bevel is 15°.

3. A durability optimization process for a spiral lifting structure, used for the spiral lifting structure according to any one of claims 1-2, characterized in that: It includes a heat treatment process for a spiral steel strip (1) and a heat treatment process for a spiral steel column (2); The heat treatment process steps of the spiral steel strip (1) are as follows: Step S1, material selection, selecting high silicon manganese spring steel strip as raw material; Step S2, pretreatment, heating the steel strip to below 700±10°C in an annealing furnace, keeping the temperature for 2-4 hours, performing spheroidizing annealing, and then slowly cooling to room temperature at a rate of ≤30°C / h to obtain spherical pearlite. After annealing, the surface of the steel strip is inspected; Step S3, cold rolling forming, using multiple cold rolling passes to change the shape of the spring steel strip, and keeping it at 250-300°C for 30 minutes after cold rolling; Step S4, quenching, uses a combination of induction heating and a protective atmosphere furnace to perform quenching treatment. First, the steel strip surface is rapidly heated to 850°C by high-frequency induction. The steel strip is then transferred to a protective atmosphere furnace and the core temperature is uniformly brought to 880°C. After the insulation is completed, the steel strip is placed in a 300°C nitrate bath for 30 minutes and then air-cooled to room temperature. Step S5, medium temperature tempering, the spiral steel strip (1) is immediately subjected to primary tempering after quenching, then oil cooling, then secondary tempering, and finally water cooling; Step S6, shot peening, wherein the surface of the heat-treated spiral steel strip (1) is struck by metal shots at high speed; Step S7, relaxation treatment, subjecting the spiral steel strip (1) to a heat-pressure relaxation treatment at an environment 20°C higher than the working temperature for 2-8 hours; Step S8, galvanizing treatment, using a cyanide-free alkaline galvanizing process to form a 20-25 μm coating on the surface of the spiral steel strip (1).

4. The durability optimization process of a spiral lifting structure according to claim 3, characterized in that: In step S3, during the cold rolling process, the total deformation is controlled to be 50%-60%.

5. The durability optimization process of a spiral lifting structure according to claim 3, characterized in that: In step S4, the holding time is extended to 3 min / mm, and the total holding time is 70 minutes.

6. The durability optimization process of a spiral lifting structure according to claim 3, characterized in that: In step S5, the first tempering is carried out at a temperature of 450° C. for 2 hours, and the second tempering is carried out at a temperature of 400° C. for 1.5 hours.

7. The durability optimization process of a spiral lifting structure according to claim 3, characterized in that: In step S6, during shot peening, metal shots with a diameter of 0.3-0.7 mm are used at a shot peening speed of 60-80 m / s, using a centrifugal shot peening machine to achieve a coverage rate of ≥200%, and the steel strip surface is struck by high-speed projectiles.

8. The durability optimization process of a spiral lifting structure according to claim 3, characterized in that: The heat treatment process steps of the spiral steel column (2) are as follows: Step R1, material selection, select medium carbon alloy steel as raw material; Step R2, normalizing treatment, heating the carbon alloy steel to 850-900°C, holding the steel at this temperature for 60±5 minutes (calculated as 1.5 minutes / mm based on the diameter), and air cooling the steel to room temperature; further air cooling the steel to room temperature to obtain uniform fine-flaked pearlite and ferrite; Step R3, hot forming processing, heating the pretreated alloy steel to 1000-1100°C, forming it on a plate rolling machine, and then using hot working to break carbides; Step R4, annealing, heating the formed spiral steel column (2) to 850-900°C in a furnace at a heating rate of 10-15°C / min and a holding time of 60±5min; then cooling it to 730±10°C and holding it isothermally for 120±5min; then cooling it to below 500±10°C in a furnace and air cooling it out of the furnace; Step R5, quenching and tempering treatment, first quenching treatment, heating the spiral steel column (2), heating it to 850-870°C in a furnace, keeping it warm for 30 minutes, heating it to 900°C and keeping it warm for 90 minutes, and then water cooling or oil cooling treatment to obtain high-strength martensite; Then, three tempering treatments are performed, and the three groups of oils are preheated to 495°C-500°C, 245°C-255°C and 25°C-35°C respectively; the spiral steel column (2) is immersed in the three groups of oils at 495-500°C, 245-255°C and 25-35°C in sequence, and each stage is kept warm for 10-15 minutes. After the oil is cooled to room temperature, the next stage of tempering is performed; Step R6, surface strengthening, the spiral steel column (2) is subjected to nitrogen and carbon co-penetration in a 540°C pit furnace, and after being kept at this temperature for 6 hours, the inner and outer sides of the spiral steel column (2) are subjected to gradient shot peening with cast steel shots and ceramic shots respectively.

9. The durability optimization process of a spiral lifting structure according to claim 8, characterized in that: In step R6, the gas flow ratio of nitrocarburizing is ammonia:propane=3:1, and the pressure in the furnace is 50-100 Pa.

10. The durability optimization process of a spiral lifting structure according to claim 8, characterized in that: In step R6, 0.6-1.0 mm cast steel shots are used for inner shot peening, with a coverage rate of ≥300% and a shot peening intensity of 0.35-0.45 N; 0.3-0.5 mm ceramic shots are used for outer shot peening, with a coverage rate of ≥200% and a shot peening intensity of 0.12-0.18 N.

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