A corrugated pipe and its injection molding method

Abstract

The present invention discloses a bellows and an injection molding method thereof. The method utilizes polyethylene and a preset formula additive to uniformly heat the polyethylene through a feeding structure to form a molten polymer fluid, thereby ensuring uniform distribution of the material within the nozzle and mold assembly. During the injection molding process, the polymer fluid is injected into the mold cavity around the mold core, thereby avoiding the occurrence of uneven flow, thereby making the distribution of the material inside the bellows blank more uniform and the structure more compact. Through a circulating liquid cooling treatment at a preset low temperature, the cooling rate and temperature distribution are effectively controlled during the cooling process, ensuring the full release of residual stress inside the bellows, thereby improving the ring stiffness and structural stability of the bellows. The method also adopts a method of heating to a preset high temperature at a preset temperature rise rate and maintaining the temperature for a preset time for heat treatment and then cooling, thereby obtaining a fatigue-resistant bellows with stronger fatigue resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of corrugated pipes, and in particular to a corrugated pipe and an injection molding method thereof. Background Art

[0002] With the increasing demand for pipes in fields such as construction, industry, and agriculture, corrugated pipes are widely used in various applications, including drainage, ventilation, and cable protection, due to their excellent flexibility, lightweight characteristics, and ability to withstand certain pressures. The corrugated structure of corrugated pipes enables them to withstand certain mechanical loads while maintaining their lightweight. However, with the increasing complexity of operating environments, especially in conditions of frequent bending and vibration, the mechanical properties and service life of traditional corrugated pipes often cannot meet the higher requirements. Therefore, improving the performance of corrugated pipes has become a key direction of technological development in the industry.

[0003] In the existing technology, the production of bellows mostly adopts the injection molding process, but after the bellows are injected, most of them only adopt natural cooling or a single liquid cooling treatment. There is a lack of precise control over the cooling rate and temperature distribution, which easily leads to insufficient release of residual stress inside the bellows, resulting in poor structural stability of the bellows, and thus fatigue damage easily occurs when repeatedly bent or vibrated.

[0004] Therefore, it is necessary to provide an injection molding method for a bellows to solve the problem that the bellows are prone to fatigue failure when repeatedly bent or vibrated and compressed. Summary of the Invention

[0005] The main purpose of the present invention is to provide a bellows and an injection molding method thereof, aiming to solve the technical problems mentioned in the above background technology.

[0006] The present invention adopts the following technical solutions:

[0007] A method for injection molding a corrugated pipe, comprising:

[0008] S100: Providing an injection molding device, the injection molding device comprising a feeding structure, a nozzle, and a mold assembly, the nozzle being in communication with the feeding structure and the mold assembly, the mold assembly comprising a plurality of mold cavities, mold cores being connected to opposite sides of the mold cavities, and the nozzle being disposed between two of the mold cores;

[0009] S200: heating polyethylene and a preset formula additive through the feeding structure to form a molten polymer fluid;

[0010] S300: injecting the polymer fluid into the mold cavity through the nozzle, so that the polymer fluid surrounds the mold core to form a bellows blank;

[0011] S400: Cooling the bellows blank by continuously cooling the bellows blank at a preset low temperature through circulating liquid cooling to obtain a bellows with high ring stiffness;

[0012] S500: heating the high ring stiffness bellows to a preset high temperature at a preset temperature rise rate and keeping the temperature for a preset time, and slowly cooling the high ring stiffness bellows to room temperature due to thermal inertia, thereby obtaining a fatigue-resistant bellows with high ring stiffness;

[0013] S600: performing a fatigue strength test on the fatigue-resistant bellows to obtain a fatigue life curve, and determining whether the fatigue-resistant bellows meets a preset target. If the fatigue-resistant bellows does not meet the preset target, segmenting the fatigue-resistant bellows to obtain a plurality of tube coils;

[0014] S700: Obtain the ring stiffness of the plurality of pipe rings and calculate the ring stiffness variance based on the plurality of ring stiffnesses to determine whether the fatigue-resistant bellows meets the preset ring stiffness. If so, increase the preset high temperature; if not, reduce the preset low temperature.

[0015] Furthermore, the preset formula additives include antioxidants, anti-ultraviolet agents and plasticizers;

[0016] The antioxidant is a mixture of one or more of 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite or dioctylene dilaurate thiodipropionate;

[0017] The anti-ultraviolet agent is a mixture of one or more of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole, dibenzoylmethane or diphenyl (2,4,6-trichlorophenyl) dithiophosphate;

[0018] The plasticizer is a mixture of one or more of dibutyl phthalate, diisooctyl phthalate or dioctyl terephthalate;

[0019] Among them, in the polymer fluid, calculated by mass percentage, the antioxidant accounts for 0.4-0.6%, the anti-ultraviolet agent accounts for 0.9-1.1%, the plasticizer accounts for 1.8-2.1%, and the balance is the polyethylene.

[0020] Furthermore, the step of heating the polyethylene and the preset formula additives through the feeding structure to form a molten polymer fluid specifically includes:

[0021] S210: uniformly mixing the polyethylene, antioxidant, anti-ultraviolet agent and plasticizer and drying the mixture to obtain a mixed base material;

[0022] S220: adding the mixed base material to the feeding structure, wherein the feeding structure is provided with a heating unit and a degassing unit, dynamically heating the mixed base material to 140° C. to 180° C. by the heating unit to melt the mixed base material, and performing vacuum degassing on the melted mixed base material by the degassing unit based on a preset negative pressure value;

[0023] S230: stirring the vacuum degassed melt at a preset rotation speed and a preset frequency to disperse the antioxidant, anti-ultraviolet agent, and plasticizer in the polyethylene, eliminate the temperature difference between the melts, and form a uniform polymer fluid;

[0024] S240: finely filtering the uniform polymer fluid to remove impurities and particles in the polymer fluid.

[0025] Furthermore, the step of injecting the polymer fluid into the mold cavity through the nozzle so that the polymer fluid surrounds the mold core to form the corrugated tube blank specifically includes:

[0026] S310: dividing the polymer fluid from the nozzle into a plurality of uniform fluid branches, and distributing the fluid branches according to the mold cavity to obtain a polymer fluid distribution path matching the mold cavity;

[0027] S320: guiding the polymer fluid distribution path into the mold cavity according to the geometric structure of the mold cavity, and guiding the polymer fluid based on the gradient guide groove to control the flow rate and direction of the polymer fluid to obtain a uniformly distributed polymer fluid flow field;

[0028] S330: adjusting the pressure distribution of the polymer fluid based on the polymer fluid flow field and the structure of the mold core to obtain a polymer fluid coating layer that uniformly fits the mold core;

[0029] S340: applying extrusion force to the polymer fluid in the mold cavity, and allowing the polymer fluid coating layer to completely wrap the mold core, thereby obtaining a corrugated pipe blank.

[0030] Furthermore, the injection molding device also includes a demolding structure, which includes a bracket, and a number of the mold cores are symmetrically arranged on two opposite sides of the bracket, and the bracket is detachably connected to the number of the mold cores. An extrusion groove is provided in the middle of the bracket, and a push rod is connected to one end of the mold core facing the extrusion groove. A cylinder is provided above the push rod, and the output shaft of the cylinder is connected to a number of extrusion tapered columns, and the extrusion tapered columns are arranged corresponding to the push rod.

[0031] Furthermore, after the step of injecting the polymer fluid into the mold cavity through the nozzle so that the polymer fluid surrounds the mold core to form the corrugated tube blank, the method further includes:

[0032] S350: placing the mold core wrapped with the corrugated tube blank on the bracket;

[0033] S360: activating the air cylinder to drive the extrusion tapered column to descend toward the extrusion groove, so that the extrusion tapered column contacts the push rod and applies a gradually increasing extrusion force to the push rod;

[0034] S370: The push rod is forced to push the mold core toward a direction away from the extrusion groove, and the mold core gradually separates from the bracket and is pushed out to a predetermined position;

[0035] S380: Separating the corrugated tube blank from the mold core to complete demoulding of the corrugated tube blank.

[0036] Furthermore, the step of cooling the bellows blank and continuously cooling the bellows blank by circulating liquid cooling at a preset low temperature to obtain a high ring stiffness bellows specifically includes:

[0037] S410: placing the bellows blank in a cooling treatment system for pre-cooling treatment, so that the surface of the bellows blank drops to a preset initial cooling temperature, thereby obtaining a pre-cooled bellows blank;

[0038] S420: Adjusting the cooling treatment system to a preset low temperature, and placing the pre-cooled bellows blank into a cooling tank for uniform liquid cooling treatment to obtain a preliminarily cooled bellows blank, wherein the cooling tank includes a plurality of circulating cooling nozzles and a temperature control unit, and the temperature control unit controls the temperature of the circulating cooling nozzles;

[0039] S430: moving the preliminarily cooled bellows blank to a preset low-temperature air cooling area, and uniformly spraying cold air on the inner and outer surfaces of the bellows blank;

[0040] S440: placing the bellows blank after the cold air is sprayed in a preset static area for stabilization treatment, so that the bellows blank gradually reaches a thermal equilibrium state, and obtaining a high ring stiffness bellows.

[0041] Furthermore, the step of heating the high ring stiffness bellows to a preset high temperature at a preset temperature rise rate and keeping the temperature for a preset time, and slowly cooling the high ring stiffness bellows to room temperature by thermal inertia to obtain a fatigue-resistant bellows with high ring stiffness specifically includes:

[0042] S510: placing the high ring stiffness bellows in a constant temperature heating furnace to obtain actual temperature change data during the heating process;

[0043] S520: Controlling the heating furnace to a preset temperature rise rate according to the actual temperature change data, so that the bellows is evenly heated to a preset high temperature, and continuously heating at the preset high temperature for a preset time;

[0044] S530: During the continuous heating process, monitoring the internal pressure change of the high ring stiffness bellows and calculating the expansion rate of the high ring stiffness bellows;

[0045] S540: Determine whether the expansion rate satisfies a preset change value; if the expansion rate does not satisfy the preset change value, change the heating variable until the expansion rate satisfies the preset change value;

[0046] S550: slowly cooling the high ring stiffness bellows to room temperature by thermal inertia to obtain a fatigue-resistant bellows with high ring stiffness.

[0047] Furthermore, the step of obtaining the ring stiffness of the plurality of pipe rings and calculating the ring stiffness variance based on the plurality of ring stiffnesses to determine whether the fatigue-resistant bellows meets the preset ring stiffness specifically includes:

[0048] S710: measuring the ring stiffness of each segmented pipe ring, compressing the pipe ring using a preset compression load, measuring the deformation of each pipe ring, and obtaining ring stiffness data of each pipe ring;

[0049] S720: Calculating the ring stiffness variance of the plurality of pipe rings based on the ring stiffness data of each pipe ring, and comparing the ring stiffness variance with the preset ring stiffness to determine whether the ring stiffness variance satisfies the preset ring stiffness, thereby obtaining a first determination result;

[0050] S730: Compare the ring stiffness data of each pipe ring with the preset ring stiffness respectively, determine whether the number of all ring stiffness data that meet the preset ring stiffness is greater than a preset threshold, and obtain a second judgment result;

[0051] S740: If both the first judgment result and the second judgment result are yes, the fatigue-resistant bellows meets the preset ring stiffness; if either the first judgment result or the second judgment result is no, the fatigue-resistant bellows does not meet the preset ring stiffness.

[0052] The present invention also provides a bellows, which is realized by the injection molding method of the bellows as described in any of the above items. The bellows includes a bellows body and two connecting ports, and the two connecting ports are respectively arranged at the opposite ends of the bellows body. The bellows body and the two connecting ports are provided with a stripping groove on the same side.

[0053] Beneficial effects:

[0054] In the present invention, polyethylene and a preset formula of additives are precisely controlled and uniformly heated through a feeding structure to form a molten polymer fluid, ensuring uniform distribution of the material within the nozzle and mold assembly. During the injection molding process, the polymer fluid is injected into the mold cavity around the mold core, avoiding the occurrence of uneven flow, thereby making the distribution of material inside the bellows blank more uniform and the structure more compact. Through circulating liquid cooling treatment at a preset low temperature, the cooling rate and temperature distribution are effectively controlled during the cooling process, ensuring the full release of residual stress inside the bellows, thereby improving the ring stiffness and structural stability of the bellows. A method of heating to a preset high temperature at a preset temperature rise rate and maintaining the temperature for a preset time is adopted for heat treatment and then cooling, thereby obtaining fatigue-resistant bellows with stronger fatigue resistance. In addition, a detection method for fatigue-resistant bellows is also used to further correct and ensure the quality of the injection molded product, effectively avoiding the problem of fatigue damage of the bellows when repeatedly bent or vibrated. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic flow chart of an injection molding method for a corrugated pipe according to the present invention;

[0056] Figure 2 It is a flow chart of another embodiment of the present invention.

[0057] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0058] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0059] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0060] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections, direct connections, or indirect connections through an intermediate medium; they may refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0061] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0062] Reference Figure 1 The present invention provides a method for injection molding a corrugated pipe, comprising:

[0063] S100: Providing an injection molding device, the injection molding device comprising a feeding structure, a nozzle, and a mold assembly, the nozzle being in communication with the feeding structure and the mold assembly, the mold assembly comprising a plurality of mold cavities, mold cores being connected to opposite sides of the mold cavities, and the nozzle being disposed between two of the mold cores;

[0064] In step S100, the injection molding device includes a feeding structure, a nozzle and a mold assembly. The function of the feeding structure is to accurately deliver polyethylene and preset formula additives to the nozzle part. The structure can be composed of a feeding hopper, a screw, a heater and a control system. The feeding hopper is responsible for storing the mixed material, and the screw pushes the material from the feeding hopper to the heater by rotation to heat it to a molten state. The nozzle is connected to the feeding structure and the mold assembly and is used to inject the molten polymer fluid into the mold cavity. The mold assembly is equipped with multiple mold cavities, and each mold cavity is connected to two opposite sides with a mold core. The mold core is designed to form the inner and outer shapes of the bellows to ensure the precision and consistency of the final bellows. In this embodiment, the mold cavities are preferably set to 8, and the mold cores are 16, and the injection holes formed are also 16. The nozzle is set between the two mold cores, and the number of the mold cavities is the same as 8, so that the polymer fluid can be injected into the mold cavity from the middle, ensuring that the plastic flows evenly and is filled, and avoiding the formation of irregular flow or cooling areas. During the specific operation, the feeding structure needs to be heated to maintain it in the appropriate temperature range, and the mold assembly needs to be adjusted to ensure that its connection with the nozzle is unobstructed so that normal injection molding operation can be carried out.

[0065] S200: heating polyethylene and a preset formula additive through the feeding structure to form a molten polymer fluid;

[0066] In step S200, polyethylene and preset formula additives are heated through the feeding structure to form a polymer fluid in a molten state. Specifically, the calculated polyethylene and preset formula additives are added to the feeding hopper in proportion, and then the feeding structure is started, and the heating and screw rotation devices are turned on. A control system can be set up so that the heater heats the material to a temperature within the range of 140°C to 180°C for melting, while the screw gradually pushes the mixture into the heating zone to achieve melting by continuously heating the material. During the entire process, the temperature control system monitors temperature changes in real time to ensure that the molten material maintains a uniform and consistent melt state, and finally forms a stable and uniform polymer fluid so that it can enter the mold assembly through the nozzle. During this process, attention should be paid to controlling the heating rate and material flow rate to avoid quality problems caused by overheating or insufficient heating.

[0067] S300: injecting the polymer fluid into the mold cavity through the nozzle, so that the polymer fluid surrounds the mold core to form a bellows blank;

[0068] In step S300, ensure that the polymer fluid is injected into the mold cavity through the nozzle so that it evenly surrounds the mold core to form a bellows blank. The molten polymer fluid entering from the feeding structure is rapidly distributed to each mold cavity under the pressure in the nozzle. Set the injection speed and pressure of the nozzle to ensure that all mold cavities are filled with liquid material in a short time. Each mold core in the mold is evenly distributed to ensure that the material is formed around the mold core to avoid uneven flow problems. After the injection is completed, maintain a certain pressure to ensure that the material completely fills every corner of the mold cavity to prevent deformation or gaps. At the same time, monitor the temperature of the mold and nozzle to maintain a stable molding state, and finally obtain a bellows blank with uniform size and dense texture.

[0069] S400: Cooling the bellows blank by continuously cooling the bellows blank at a preset low temperature through circulating liquid cooling to obtain a bellows with high ring stiffness;

[0070] In step S400, the bellows blank that has completed injection molding is removed from the mold cavity and then cooled. During the cooling process, a preset low-temperature circulating liquid cooling technology is used to continuously cool the bellows blank. The specific operating steps include: first, the bellows blank is placed in the cooling treatment area, the cooling system is started, and appropriate low-temperature parameters are set. The coolant is introduced from the liquid storage tank into the cooling pipe through a circulating pump, and then evenly sprayed onto the surface of the bellows blank to uniformly cool the entire blank. During this process, the temperature and flow of the coolant are precisely controlled by the temperature control system to ensure that the temperature of the blank drops evenly from the inside to the outside, thereby minimizing the generation of internal stress. During the entire cooling cycle, the temperature changes of the bellows blank are continuously monitored to ensure that it reaches a stable temperature in the cooling chamber, and finally a bellows with high ring stiffness is obtained.

[0071] S500: heating the high ring stiffness bellows to a preset high temperature at a preset temperature rise rate and keeping the temperature for a preset time, and slowly cooling the high ring stiffness bellows to room temperature due to thermal inertia, thereby obtaining a fatigue-resistant bellows with high ring stiffness;

[0072] In step S500, the cooled high-ring stiffness bellows is gradually heated to a preset high temperature at a preset temperature rise rate, and maintained for a certain period of time, so that the bellows is evenly heated and residual stress is eliminated as much as possible. The specific setting of the gradual heating speed can be controlled at about 5°C per minute, so that the temperature of the bellows blank gradually rises to the range of 110°C to 130°C. After reaching the preset high temperature, the temperature is kept constant for a certain period of time to ensure that the internal and external temperatures of the bellows blank are consistent, evenly heated, and the stress is fully released. After the insulation stage is over, the heating system is gradually turned off, and the thermal inertia is used to slowly cool the bellows to room temperature to avoid the rebound of internal stress caused by sudden cooling, and finally a fatigue-resistant bellows with high ring stiffness is obtained.

[0073] S600: performing a fatigue strength test on the fatigue-resistant bellows to obtain a fatigue life curve, and determining whether the fatigue-resistant bellows meets a preset target. If the fatigue-resistant bellows does not meet the preset target, segmenting the fatigue-resistant bellows to obtain a plurality of tube coils;

[0074] In step S600, the fatigue-resistant bellows that have undergone heat treatment need to undergo fatigue strength testing to obtain their fatigue life curve and determine whether their performance meets the standards. First, fix the bellows sample on a fatigue testing machine, set the parameters of the periodic alternating load, and start the testing machine for vibration loading. During the loading process, the material deformation, stress and strain of the bellows are monitored in real time, and the test data of each cycle is recorded until the sample fails or the preset number of test cycles is reached. A fatigue life curve is generated based on the test results, and compared with the preset standards to determine whether the bellows meets the required fatigue performance requirements. If the fatigue life does not meet the standards, the bellows needs to be divided into multiple pipe rings for subsequent detailed ring stiffness testing to determine the specific fatigue damage location and cause.

[0075] S700: Obtain the ring stiffness of the plurality of pipe rings and calculate the ring stiffness variance based on the plurality of ring stiffnesses to determine whether the fatigue-resistant bellows meets the preset ring stiffness. If so, increase the preset high temperature; if not, reduce the preset low temperature.

[0076] In step S700, the ring stiffness of the segmented tube rings is measured to obtain the ring stiffness data of each tube ring, and the ring stiffness variance is calculated to judge the overall performance of the fatigue-resistant bellows. The segmented tube rings are placed one by one in the ring stiffness testing device, and pressure is applied to them through a preset compression load. The deformation of the tube ring is recorded during the measurement process to obtain the ring stiffness value of each tube ring. After completing the test of all tube rings, the ring stiffness data is calculated, and the ring stiffness variance of each tube ring is comprehensively calculated by the data processing system, and these data are compared with the preset ring stiffness standard. If the calculation result shows that the ring stiffness variance is within the preset standard range, the preset high temperature is increased. If it is not within the range, the preset low temperature is lowered, and the adjustment parameters are recorded for subsequent production. Ultimately, in this way, the consistency and reliability of the injection molding process and cooling treatment are ensured, and the overall quality and life of the bellows are improved.

[0077] In summary, precise control of polyethylene and a preset formula of additives is used to uniformly heat the material through the feed structure to form a molten polymer fluid, ensuring uniform distribution of the material within the nozzle and mold assembly. During the injection molding process, the polymer fluid is injected into the mold cavity around the mold core, avoiding the occurrence of uneven flow, thereby achieving a more uniform distribution of material within the bellows blank and a denser structure. Through circulating liquid cooling at a preset low temperature, the cooling rate and temperature distribution are effectively controlled during the cooling process, ensuring the full release of residual stress within the bellows, thereby improving the ring stiffness and structural stability of the bellows. Heat treatment is performed by heating to a preset high temperature at a preset temperature rise rate and holding at that temperature for a preset time before cooling, resulting in fatigue-resistant bellows with stronger fatigue resistance. Furthermore, testing methods for fatigue-resistant bellows are used to further improve the quality of the injection-molded products, effectively avoiding fatigue damage to the bellows when repeatedly bent or subjected to vibration and pressure.

[0078] In one embodiment, the predetermined formula additives include antioxidants, UV inhibitors, and plasticizers;

[0079] The antioxidant is a mixture of one or more of 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite or dioctylene dilaurate thiodipropionate;

[0080] The anti-ultraviolet agent is a mixture of one or more of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole, dibenzoylmethane or diphenyl (2,4,6-trichlorophenyl) dithiophosphate;

[0081] The plasticizer is a mixture of one or more of dibutyl phthalate, diisooctyl phthalate or dioctyl terephthalate;

[0082] Among them, in the polymer fluid, calculated by mass percentage, the antioxidant accounts for 0.4-0.6%, the anti-ultraviolet agent accounts for 0.9-1.1%, the plasticizer accounts for 1.8-2.1%, and the balance is the polyethylene.

[0083] In this embodiment, antioxidants effectively prevent polyethylene from oxidative degradation during processing and use, thereby extending the service life of the bellows. 2,6-Di-tert-Butyl-p-cresol exhibits excellent thermal stability and antioxidant properties; tris(2,4-di-tert-butylphenyl)phosphite exhibits even higher antioxidant efficiency, making it particularly suitable for applications in high-temperature environments; and dioctylthiodipropionate dilaurate is a highly effective thioester antioxidant that significantly improves the material's weather resistance.

[0084] UV inhibitors absorb or reflect UV rays, preventing them from damaging the polyethylene material and thus maintaining the corrugated pipe's color and performance. 2-(2-Hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole is a highly effective benzotriazole UV inhibitor with a broad absorption range and excellent light stability. Dibenzoylmethane is an organic compound that absorbs UV rays and can be used in the production of outdoor products. Diphenyl (2,4,6-trichlorophenyl) dithiophosphate has excellent hydrolysis resistance and is suitable for use in humid environments.

[0085] Plasticizers are used to improve the processing properties and flexibility of polyethylene materials, making them easier to injection mold. Dibutyl phthalate has good compatibility and low-temperature performance; diisooctyl phthalate has higher heat resistance and migration resistance, making it suitable for high-temperature and long-term use; and dioctyl terephthalate is an environmentally friendly plasticizer with low toxicity and good biodegradability.

[0086] Specifically, antioxidants, UV inhibitors, and plasticizers are added to the polymer fluid in specific proportions and then processed and molded using an injection molding machine. The antioxidant accounts for 0.4-0.6%, effectively preventing oxidative degradation; the UV inhibitor, at 0.9-1.1%, significantly improves the material's weather resistance and aging resistance; and the plasticizer, at 1.8-2.1%, improves its processing properties and flexibility. The balance is polyethylene, the primary component of the corrugated pipe, which provides excellent mechanical properties and chemical stability.

[0087] In one embodiment, the step of heating the polyethylene and the preset formula additives through the feeding structure to form a molten polymer fluid specifically includes:

[0088] S210: uniformly mixing the polyethylene, antioxidant, anti-ultraviolet agent and plasticizer and drying the mixture to obtain a mixed base material;

[0089] S220: adding the mixed base material to the feeding structure, wherein the feeding structure is provided with a heating unit and a degassing unit, dynamically heating the mixed base material to 140° C. to 180° C. by the heating unit to melt the mixed base material, and performing vacuum degassing on the melted mixed base material by the degassing unit based on a preset negative pressure value;

[0090] S230: stirring the vacuum degassed melt at a preset rotation speed and a preset frequency to disperse the antioxidant, anti-ultraviolet agent, and plasticizer in the polyethylene, eliminate the temperature difference between the melts, and form a uniform polymer fluid;

[0091] S240: finely filtering the uniform polymer fluid to remove impurities and particles in the polymer fluid.

[0092] In this embodiment, the polyethylene, antioxidant, UV inhibitor, and plasticizer are uniformly mixed in step S210. This step ensures that the components are evenly distributed during subsequent processing. The mixed materials are also dried to remove moisture and prevent bubbles from forming during the injection molding process, which could affect the quality of the bellows.

[0093] In S220, the dried mixed base material is added to the feed structure. The feed structure is equipped with a heating unit and a degassing unit. The heating unit dynamically heats the mixed base material to a molten state between 140°C and 180°C. Simultaneously, the degassing unit vacuum degasses the molten mixed base material at a preset negative pressure to remove gases and volatile substances, ensuring the purity of the melt.

[0094] In S230, the vacuum degassed melt is stirred at a preset rotational speed and frequency. This step aims to disperse the antioxidant, UV inhibitor, and plasticizer more evenly throughout the polyethylene, while also eliminating temperature differences within the melt to form a uniform polymer fluid.

[0095] The S240 precisely filters the uniform polymer fluid. The fine screening action of the filter removes impurities and particles from the polymer fluid, ensuring the final molded bellows has excellent performance and appearance. These steps are closely linked and together constitute the key links in the bellows injection molding process.

[0096] In one embodiment, the step of injecting the polymer fluid into the mold cavity through the nozzle so that the polymer fluid surrounds the mold core to form the corrugated tube blank specifically includes:

[0097] S310: dividing the polymer fluid from the nozzle into a plurality of uniform fluid branches, and distributing the fluid branches according to the mold cavity to obtain a polymer fluid distribution path matching the mold cavity;

[0098] S320: guiding the polymer fluid distribution path into the mold cavity according to the geometric structure of the mold cavity, and guiding the polymer fluid based on the gradient guide groove to control the flow rate and direction of the polymer fluid to obtain a uniformly distributed polymer fluid flow field;

[0099] S330: adjusting the pressure distribution of the polymer fluid based on the polymer fluid flow field and the structure of the mold core to obtain a polymer fluid coating layer that uniformly fits the mold core;

[0100] S340: applying extrusion force to the polymer fluid in the mold cavity, and allowing the polymer fluid coating layer to completely wrap the mold core, thereby obtaining a corrugated pipe blank.

[0101] In this embodiment, step S310 involves dividing the polymer fluid output from the nozzle into multiple uniform fluid branches, thereby ensuring that the fluid can be evenly and effectively distributed to various parts of the mold cavity and avoiding local accumulation or loss of fluid in the mold cavity.

[0102] In step S320, these fluid branches are directed into the mold cavity according to the mold cavity geometry. In this process, the gradient guide groove plays a key role, not only controlling the flow rate of the polymer fluid but also ensuring the correct direction of the fluid within the mold cavity, thereby forming a uniformly distributed polymer fluid flow field.

[0103] The S330 focuses on adjusting the pressure distribution of the polymer fluid so that it evenly adheres to the mold core. This step is crucial because it directly affects the quality of the bellows blank. By precisely adjusting the polymer fluid pressure, it ensures that the fluid forms a uniform layer around the mold core.

[0104] In S340, extrusion pressure is applied to the polymer fluid in the mold cavity, causing it to completely wrap around the mold core. This step is critical to the formation of the bellows blank, ensuring that the polymer fluid can fit tightly against the mold core and, after cooling and solidification, form a bellows blank with a uniform corrugated structure, ensuring high quality and consistency of the bellows.

[0105] In one embodiment, the injection molding device further includes a demolding structure, which includes a bracket, a plurality of mold cores are symmetrically arranged on opposite sides of the bracket, and the bracket is detachably connected to the plurality of mold cores, an extrusion groove is provided in the middle of the bracket, and a push rod is connected to one end of the mold core facing the extrusion groove, a cylinder is provided above the push rod, and the output shaft of the cylinder is connected to a plurality of extrusion tapered columns, and the extrusion tapered columns are provided corresponding to the push rod.

[0106] In this embodiment, the injection molding apparatus also includes a demolding mechanism designed to efficiently and accurately demold the bellows. A bracket serves as a support component during demolding. Multiple mold cores are symmetrically arranged on either side of the bracket, embedded in specific holes within the bracket. A pre-defined extrusion groove is located in the center of the bracket, providing the necessary space for the downward pressure of the extrusion taper column during demolding.

[0107] Each mold core is connected to a push rod on the end facing the extrusion groove. This push rod, located within the groove, plays a key role in demolding. A pneumatic cylinder is mounted above the push rod. Its output shaft is connected to multiple tapered extrusion columns, each corresponding to a push rod. When the demolding process is initiated, the cylinder drives the columns downward, pushing the mold core and the corrugated tube blank attached to it out of the groove via the push rod.

[0108] In one embodiment, after the step of injecting the polymer fluid into the mold cavity through the nozzle so that the polymer fluid surrounds the mold core to form the corrugated tube blank, the method further includes:

[0109] S350: placing the mold core wrapped with the corrugated tube blank on the bracket;

[0110] S360: activating the air cylinder to drive the extrusion tapered column to descend toward the extrusion groove, so that the extrusion tapered column contacts the push rod and applies a gradually increasing extrusion force to the push rod;

[0111] S370: The push rod is forced to push the mold core toward a direction away from the extrusion groove, and the mold core gradually separates from the bracket and is pushed out to a predetermined position;

[0112] S380: Separating the corrugated tube blank from the mold core to complete demoulding of the corrugated tube blank.

[0113] In this embodiment, in S350, the mold core wrapped with the corrugated tube blank is placed on the bracket to ensure that the position of the mold core is accurate so that the subsequent demolding operation can be carried out smoothly.

[0114] In step S360, the cylinder is activated, driving the extrusion taper column downward toward the extrusion groove. During this process, the extrusion taper column gradually contacts the push rod and begins to apply a gradually increasing extrusion pressure to the push rod. Extrusion pressure is the key to the demolding process, ensuring that the corrugated tube blank can be smoothly separated from the mold core.

[0115] In S370, the push rod, under the pressure of the extrusion force, gradually pushes the mold core away from the extrusion groove. As the mold core moves, it gradually detaches from the bracket and falls to a predetermined position. The predetermined position can be set to facilitate the collection of the mold core or to facilitate the subsequent separation of the corrugated tube blank from the mold core.

[0116] In S380, the bellows blank is separated from the mold core. At this point, the bellows blank has completed the demoulding process and can be taken out for subsequent processing or testing.

[0117] In one embodiment, the step of cooling the bellows blank, wherein the bellows blank is continuously cooled by circulating liquid cooling at a preset low temperature to obtain a high ring stiffness bellows, specifically includes:

[0118] S410: placing the bellows blank in a cooling treatment system for pre-cooling treatment, so that the surface of the bellows blank drops to a preset initial cooling temperature, thereby obtaining a pre-cooled bellows blank;

[0119] S420: Adjusting the cooling treatment system to a preset low temperature, and placing the pre-cooled bellows blank into a cooling tank for uniform liquid cooling treatment to obtain a preliminarily cooled bellows blank, wherein the cooling tank includes a plurality of circulating cooling nozzles and a temperature control unit, and the temperature control unit controls the temperature of the circulating cooling nozzles;

[0120] S430: moving the preliminarily cooled bellows blank to a preset low-temperature air cooling area, and uniformly spraying cold air on the inner and outer surfaces of the bellows blank;

[0121] S440: placing the bellows blank after the cold air is sprayed in a preset static area for stabilization treatment, so that the bellows blank gradually reaches a thermal equilibrium state, and obtaining a high ring stiffness bellows.

[0122] In this embodiment, in S410, the bellows blank is placed in a cooling treatment system for pre-cooling treatment. This process quickly reduces the surface temperature of the blank. In step S420, the temperature of the cooling treatment system is adjusted to a preset low temperature state. The pre-cooled bellows blank is placed in a cooling tank. Through the coordinated action of several circulating cooling nozzles and a temperature control unit, uniform liquid cooling treatment of the blank is achieved, ensuring the uniformity of the overall cooling effect of the bellows.

[0123] In S430, the initially cooled bellows blank is moved to a low-temperature air cooling area, where a uniform spray of cold air is applied to the inner and outer surfaces of the blank. This helps eliminate residual stress during the cooling process and improves the overall performance of the bellows. Finally, in S440, the cold air-treated bellows blank is placed in a pre-set static area for stabilization. Once the bellows temperature returns to room temperature, the blank gradually reaches thermal equilibrium, resulting in a bellows with high ring stiffness.

[0124] In one embodiment, the step of heating the high ring stiffness bellows to a preset high temperature at a preset temperature rise rate and keeping the temperature for a preset time, and slowly cooling the high ring stiffness bellows to room temperature by thermal inertia to obtain a fatigue-resistant bellows with high ring stiffness specifically includes:

[0125] S510: placing the high ring stiffness bellows in a constant temperature heating furnace to obtain actual temperature change data during the heating process;

[0126] S520: Controlling the heating furnace to a preset temperature rise rate according to the actual temperature change data, so that the bellows is evenly heated to a preset high temperature, and continuously heating at the preset high temperature for a preset time;

[0127] S530: During the continuous heating process, monitoring the internal pressure change of the high ring stiffness bellows and calculating the expansion rate of the high ring stiffness bellows;

[0128] S540: Determine whether the expansion rate satisfies a preset change value; if the expansion rate does not satisfy the preset change value, change the heating variable until the expansion rate satisfies the preset change value;

[0129] S550: slowly cooling the high ring stiffness bellows to room temperature by thermal inertia to obtain a fatigue-resistant bellows with high ring stiffness.

[0130] In this embodiment, in step S510, the high-ring-rigidity bellows is first placed in a constant-temperature heating furnace. In step S520, the system accurately controls the heating rate of the heating furnace according to the actual temperature change data, so that it gradually heats up to the preset high temperature according to the preset temperature rise rate. This process ensures that the bellows can be heated evenly and avoids the degradation of material properties due to rapid temperature rise. The specific temperature values of the preset temperature rise rate and the preset high temperature can be determined according to the material properties and required performance of the high-ring-rigidity bellows. Preferably, the bellows with polyethylene as the base material in this embodiment has a preset temperature rise rate set to 5 degrees Celsius per minute and a preset high temperature set to 100 degrees Celsius.

[0131] In step S530, the system continuously monitors the internal pressure changes of the bellows and calculates the expansion rate of the bellows based on this, which plays an important role in evaluating the thermal stability and fatigue resistance of the bellows. If the expansion rate is determined not to meet the preset change value in step S540, it means that the thermal expansion performance of the bellows has not yet met expectations. At this time, it is necessary to adjust the heating variables, such as heating time and temperature, until the expansion rate meets the preset change value. Finally, in step S550, the bellows is slowly cooled to room temperature through the principle of thermal inertia. This process helps to eliminate residual stress inside the bellows, thereby improving fatigue resistance while ensuring its ring stiffness.

[0132] In one embodiment, the step of obtaining the ring stiffness of the plurality of pipe rings and calculating the ring stiffness variance based on the plurality of ring stiffnesses to determine whether the fatigue-resistant bellows meets the preset ring stiffness specifically includes:

[0133] S710: measuring the ring stiffness of each segmented pipe ring, compressing the pipe ring using a preset compression load, measuring the deformation of each pipe ring, and obtaining ring stiffness data of each pipe ring;

[0134] S720: Calculating the ring stiffness variance of the plurality of pipe rings based on the ring stiffness data of each pipe ring, and comparing the ring stiffness variance with the preset ring stiffness to determine whether the ring stiffness variance satisfies the preset ring stiffness, thereby obtaining a first determination result;

[0135] S730: Compare the ring stiffness data of each pipe ring with the preset ring stiffness respectively, determine whether the number of all ring stiffness data that meet the preset ring stiffness is greater than a preset threshold, and obtain a second judgment result;

[0136] S740: If both the first judgment result and the second judgment result are yes, the fatigue-resistant bellows meets the preset ring stiffness; if either the first judgment result or the second judgment result is no, the fatigue-resistant bellows does not meet the preset ring stiffness.

[0137] In this embodiment, at S71, the ring stiffness data for each pipe ring is obtained. By applying a preset compressive load, the deformation of the pipe ring is observed and recorded, and the ring stiffness data is calculated. At S720, a statistical analysis of the ring stiffness data is performed, calculating the total ring stiffness variance for all pipe rings. This variance is compared with the preset ring stiffness to determine whether the ring stiffness variance meets the preset ring stiffness, thereby obtaining a first determination result. This can determine the degree of data dispersion, that is, whether the ring stiffness of each pipe ring is stable and meets the preset requirements.

[0138] S730 further performs individual judgment on the ring stiffness data of each pipe ring to see whether they all meet the preset ring stiffness, and further counts the number of pipe rings that meet the preset ring stiffness to see whether it is greater than a preset threshold, thereby obtaining a second judgment result.

[0139] In step S740, the judgment results of the first two steps are summarized and judged. If both the first and second judgment results are positive, that is, when the ring stiffness data of all pipe rings are stable and meet the preset requirements, the fatigue-resistant bellows is judged to meet the preset ring stiffness. If either the first and second judgment results are negative, or both are negative, the fatigue-resistant bellows is judged to fail to meet the preset ring stiffness requirements.

[0140] Furthermore, if the fatigue-resistant bellows cannot meet the preset fatigue strength target, the preset high temperature during the heat treatment of the bellows in S500 is increased if the bellows meets the preset ring stiffness. If the bellows cannot meet the preset ring stiffness, the preset low temperature during the cooling treatment in S400 is reduced. By adjusting the manufacturing process based on multi-level judgment conditions and feedback from the multi-level judgment results, the performance of the bellows is optimized. This ensures that even if deviations occur during the manufacturing process, they can be corrected by adjusting the process parameters, thereby ensuring the quality and performance of the final product and resolving the problem of fatigue failure of the bellows caused by repeated bending or vibration pressure.

[0141] The present invention also provides a bellows, which is realized by the injection molding method of the bellows as described in any of the above items, and includes a bellows body and two connecting ports, the two connecting ports are respectively arranged at the opposite ends of the bellows body, and the bellows body and the two connecting ports are provided with a stripping groove on the same side.

[0142] In the above embodiment, the bellows body serves as the core of the bellows, responsible for bearing pressure and transmitting fluid, while two connection ports are provided at either end of the bellows body for connection to other pipes or equipment. A stripping groove is provided on one side of the bellows, simplifying the production process. The stripping groove design of the bellows of the present invention allows for the burrs to be removed directly as part of the stripping groove after production. Furthermore, the process of cutting the water outlet of the bellows is eliminated, thereby improving production efficiency.

[0143] Furthermore, the design of the stripping groove also reflects considerations for mold adaptability. Since bellows are typically used for fluid conveying, their glue line is often thin, and the mold core may also be narrow, placing high demands on mold precision and injection molding process. Utilizing the inevitable burrs as stripping grooves allows the mold to better adapt to these thin glue lines and narrow cores during the injection molding process, thereby ensuring product quality and performance.

[0144] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for injection molding a corrugated pipe, characterized in that: include: S100: Providing an injection molding device, the injection molding device comprising a feeding structure, a nozzle, and a mold assembly, the nozzle being in communication with the feeding structure and the mold assembly, the mold assembly comprising a plurality of mold cavities, mold cores being connected to opposite sides of the mold cavities, and the nozzle being disposed between two of the mold cores; S200: heating polyethylene and a preset formula additive through the feeding structure to form a molten polymer fluid; S300: injecting the polymer fluid into the mold cavity through the nozzle, so that the polymer fluid surrounds the mold core to form a bellows blank; S400: Cooling the bellows blank by continuously cooling the bellows blank at a preset low temperature through circulating liquid cooling to obtain a bellows with high ring stiffness; S500: heating the high ring stiffness bellows to a preset high temperature at a preset temperature rise rate and keeping the temperature for a preset time, and slowly cooling the high ring stiffness bellows to room temperature due to thermal inertia, thereby obtaining a fatigue-resistant bellows with high ring stiffness; S600: performing a fatigue strength test on the fatigue-resistant bellows to obtain a fatigue life curve, and determining whether the fatigue-resistant bellows meets a preset target. If the fatigue-resistant bellows does not meet the preset target, segmenting the fatigue-resistant bellows to obtain a plurality of tube coils; S700: Acquire the ring stiffness of the plurality of pipe rings and calculate the ring stiffness variance according to the plurality of ring stiffnesses, determine whether the fatigue-resistant bellows meets the preset ring stiffness, and if so, increase the preset high temperature; if not, reduce the preset low temperature; The step of injecting the polymer fluid into the mold cavity through the nozzle so that the polymer fluid surrounds the mold core to form the corrugated tube blank specifically includes: S310: dividing the polymer fluid from the nozzle into a plurality of uniform fluid branches, and distributing the fluid branches according to the mold cavity to obtain a polymer fluid distribution path matching the mold cavity; S320: guiding the polymer fluid distribution path into the mold cavity according to the geometric structure of the mold cavity, and guiding the polymer fluid based on the gradient guide groove to control the flow rate and direction of the polymer fluid to obtain a uniformly distributed polymer fluid flow field; S330: adjusting the pressure distribution of the polymer fluid based on the polymer fluid flow field and the structure of the mold core to obtain a polymer fluid coating layer that uniformly fits the mold core; S340: applying an extrusion force to the polymer fluid in the mold cavity, and allowing the polymer fluid coating layer to completely wrap the mold core, thereby obtaining a corrugated pipe blank; The step of obtaining the ring stiffness of the plurality of pipe rings and calculating the ring stiffness variance according to the plurality of ring stiffnesses to determine whether the fatigue-resistant bellows meets the preset ring stiffness specifically includes: S710: measuring the ring stiffness of each segmented pipe ring, compressing the pipe ring using a preset compression load, measuring the deformation of each pipe ring, and obtaining ring stiffness data of each pipe ring; S720: Calculating the ring stiffness variance of the plurality of pipe rings based on the ring stiffness data of each pipe ring, and comparing the ring stiffness variance with the preset ring stiffness to determine whether the ring stiffness variance satisfies the preset ring stiffness, thereby obtaining a first determination result; S730: Compare the ring stiffness data of each pipe ring with the preset ring stiffness respectively, determine whether the number of all ring stiffness data that meet the preset ring stiffness is greater than a preset threshold, and obtain a second judgment result; S740: If both the first judgment result and the second judgment result are yes, the fatigue-resistant bellows meets the preset ring stiffness; if either the first judgment result or the second judgment result is no, the fatigue-resistant bellows does not meet the preset ring stiffness.

2. The method for injection molding a corrugated pipe according to claim 1, characterized in that: The preset formula additives include antioxidants, anti-ultraviolet agents and plasticizers; The antioxidant is a mixture of one or more of 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite or dioctylene dilaurate thiodipropionate; The anti-ultraviolet agent is a mixture of one or more of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole, dibenzoylmethane or diphenyl (2,4,6-trichlorophenyl) dithiophosphate; The plasticizer is a mixture of one or more of dibutyl phthalate, diisooctyl phthalate or dioctyl terephthalate; Among them, in the polymer fluid, calculated by mass percentage, the antioxidant accounts for 0.4-0.6%, the anti-ultraviolet agent accounts for 0.9-1.1%, the plasticizer accounts for 1.8-2.1%, and the balance is the polyethylene.

3. The method for injection molding a corrugated pipe according to claim 2, characterized in that: The step of heating the polyethylene and the preset formula additives through the feeding structure to form a molten polymer fluid specifically includes: S210: uniformly mixing the polyethylene, antioxidant, anti-ultraviolet agent and plasticizer and drying the mixture to obtain a mixed base material; S220: adding the mixed base material to the feeding structure, wherein the feeding structure is provided with a heating unit and a degassing unit, dynamically heating the mixed base material to 140° C. to 180° C. by the heating unit to melt the mixed base material, and performing vacuum degassing on the melted mixed base material by the degassing unit based on a preset negative pressure value; S230: stirring the vacuum degassed melt at a preset rotation speed and a preset frequency to disperse the antioxidant, anti-ultraviolet agent, and plasticizer in the polyethylene, eliminate the temperature difference between the melts, and form a uniform polymer fluid; S240: finely filtering the uniform polymer fluid to remove impurities and particles in the polymer fluid.

4. The method for injection molding a corrugated pipe according to claim 1, characterized in that: The injection molding device also includes a demolding structure, which includes a bracket, and a plurality of mold cores are symmetrically arranged on opposite sides of the bracket, and the bracket is detachably connected to the plurality of mold cores. An extrusion groove is provided in the middle of the bracket, and a push rod is connected to one end of the mold core facing the extrusion groove. A cylinder is provided above the push rod, and the output shaft of the cylinder is connected to a plurality of extrusion tapered columns, and the extrusion tapered columns are provided corresponding to the push rod.

5. The method for injection molding a corrugated pipe according to claim 4, characterized in that: After the step of injecting the polymer fluid into the mold cavity through the nozzle so that the polymer fluid surrounds the mold core to form the corrugated tube blank, the method further includes: S350: placing the mold core wrapped with the corrugated tube blank on the bracket; S360: activating the air cylinder to drive the extrusion tapered column to descend toward the extrusion groove, so that the extrusion tapered column contacts the push rod and applies a gradually increasing extrusion force to the push rod; S370: The push rod is forced to push the mold core toward a direction away from the extrusion groove, and the mold core gradually separates from the bracket and is pushed out to a predetermined position; S380: Separating the corrugated tube blank from the mold core to complete demoulding of the corrugated tube blank.

6. The method for injection molding a corrugated pipe according to claim 1, characterized in that: The step of cooling the bellows blank and continuously cooling the bellows blank by circulating liquid cooling at a preset low temperature to obtain a high ring stiffness bellows specifically includes: S410: placing the bellows blank in a cooling treatment system for pre-cooling treatment, so that the surface of the bellows blank drops to a preset initial cooling temperature, thereby obtaining a pre-cooled bellows blank; S420: Adjusting the cooling treatment system to a preset low temperature, and placing the pre-cooled bellows blank into a cooling tank for uniform liquid cooling treatment to obtain a preliminarily cooled bellows blank, wherein the cooling tank includes a plurality of circulating cooling nozzles and a temperature control unit, and the temperature control unit controls the temperature of the circulating cooling nozzles; S430: moving the preliminarily cooled bellows blank to a preset low-temperature air cooling area, and uniformly spraying cold air on the inner and outer surfaces of the bellows blank; S440: placing the bellows blank after the cold air is sprayed in a preset static area for stabilization treatment, so that the bellows blank gradually reaches a thermal equilibrium state, and obtaining a high ring stiffness bellows.

7. The method for injection molding a corrugated pipe according to claim 1, characterized in that: The step of heating the high ring stiffness corrugated pipe to a preset high temperature at a preset temperature rise rate and keeping the temperature for a preset time, and slowly cooling the high ring stiffness corrugated pipe to room temperature by thermal inertia to obtain a fatigue-resistant corrugated pipe with high ring stiffness specifically includes: S510: placing the high ring stiffness bellows in a constant temperature heating furnace to obtain actual temperature change data during the heating process; S520: Controlling the heating furnace to a preset temperature rise rate according to the actual temperature change data, so that the bellows is evenly heated to a preset high temperature, and continuously heating at the preset high temperature for a preset time; S530: During the continuous heating process, monitoring the internal pressure change of the high ring stiffness bellows and calculating the expansion rate of the high ring stiffness bellows; S540: Determine whether the expansion rate satisfies a preset change value; if the expansion rate does not satisfy the preset change value, change the heating variable until the expansion rate satisfies the preset change value; S550: slowly cooling the high ring stiffness bellows to room temperature by thermal inertia to obtain a fatigue-resistant bellows with high ring stiffness.

8. A bellows, characterized in that: The bellows is realized by the injection molding method of any one of claims 1 to 7, wherein the bellows comprises a bellows body and two connecting ports, the two connecting ports are respectively arranged at opposite ends of the bellows body, and the bellows body and the two connecting ports are provided with a stripping groove on the same side.

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