An integrated forming die and process for a multi-channel dust cover

Abstract

This invention discloses an integrated molding die and process for a multi-channel dust cover. The integrated molding die includes matching cavities formed by upper and lower molds. The first peak cavity is equipped with a local heating element, and the trough cavity is equipped with an exhaust groove. It is also configured with zoned cooling channels and a PLC controller. By controlling the heating power, blowing pressure, and cooling sequence, the high temperature of the first peak area and the preferential cooling of the troughs are achieved. This process precisely controls the molding conditions of each area by adjusting the pre-distribution of the parison wall thickness, combined with local heating and time-sharing cooling steps. This application can effectively solve the problem that existing blow molding processes struggle to achieve precise molding of complex, non-uniform wall thicknesses, significantly reduce the rotational expansion of the dust cover, and improve its sealing performance and fatigue life under harsh working conditions.

Description

Technical Field

[0001] This invention relates to the field of automotive parts manufacturing technology, specifically to an integrated molding die and blow molding process for a dust cover for a multi-ball drive shaft, belonging to the field of polymer material molding and processing technology. Background Technology

[0002] The performance requirements for dust covers in multi-track drive shafts are becoming increasingly stringent. The dust cover must remain sealed for extended periods under harsh operating conditions, including a wide temperature range of -40℃ to 120℃, a maximum swing angle of 40°, and a speed of 1200r / min, without cracks or grease leakage, and the rotational expansion must be controlled within 5mm.

[0003] Existing blow-molded dust covers typically employ a uniform wall thickness design, leading to localized stress concentration, large expansion, and insufficient fatigue life under large swing angles and high speeds. To improve the wall thickness distribution, some technicians have attempted to optimize it by adjusting the pre-distribution of the parison wall thickness, but it is difficult to precisely control the complex non-uniform wall thickness structure where the first peak is thickened, the remaining peaks are thinned, and all troughs are of equal thickness.

[0004] Chinese patent CN106738737A discloses an injection molding method for thin-walled plastic parts, which uses an electromagnetic induction coil to locally heat the surface of the mold, achieving dynamic temperature changes in the mold. However, this technical solution has the following shortcomings: (1) It is applied in the field of injection molding, targeting hard thin-walled plastic parts, but not suitable for blow molding of elastomer dust covers, and the process mechanism is completely different; (2) Its heating method is high-frequency electromagnetic induction, which requires complex mathematical models and expensive induction equipment. Moreover, the temperature control is a dynamic exponential change, which is difficult to stably match the parison blowing process of the blow molding process. (3) It does not involve zoned cooling timing control, and cannot achieve differentiated cooling of specific troughs first and peaks later, thus it cannot accurately control non-uniform wall thickness; (4) It has not solved the technical problems of precise forming of non-uniform wall thickness of multi-channel dust cover and control of expansion under large swing angle.

[0005] Therefore, there is an urgent need to develop an integrated molding die and process for blow molding that can accurately form a dust cover with a thicker first peak, thinner remaining peaks, and equal thickness in the valleys, in order to meet the stringent requirements of bench testing. Summary of the Invention

[0006] This invention aims to provide an integrated molding mold and process for a multi-channel dust cover. Through the synergy of local heating elements, zoned cooling channels and PLC closed-loop control, the temperature of the first peak area is 20-30°C higher than that of other areas, and the cooling of the trough area is 3-5 seconds earlier than that of the peak area. This allows for precise control of the wall thickness of each part, significantly reducing expansion and improving product durability and yield.

[0007] To this end, the first aspect of this application provides an integral molding mold for a multi-channel dust cover, comprising: an upper mold and a lower mold, which, after being closed, form a cavity matching the corrugated shape of the dust cover; the cavity includes a first peak cavity corresponding to the first peak of the dust cover, other peak cavities, and all trough cavities; a local heating element is provided circumferentially in the first peak cavity; an exhaust groove extending circumferentially is provided on the surface of the trough cavity; the mold further includes partitioned cooling channels, including a first cooling circuit corresponding to the first peak area and a second cooling circuit corresponding to the other areas; and a temperature sensor, a pressure sensor, and a PLC controller; the PLC controller receives signals from the temperature sensor and the pressure sensor, and controls the power of the local heating element, the blowing pressure, and the opening and closing of the valves of the partitioned cooling channels, so that the temperature of the first peak area is 20-30°C higher than that of other areas, and the cooling of the trough area starts 3-5 seconds earlier than that of the peak area.

[0008] By adopting the above technical solution, during the blow molding process, the local heating element makes the mold temperature of the first peak area significantly higher than that of other areas (temperature difference 20-30℃). The high temperature reduces the melt viscosity, making the material easier to flow and accumulate, thus forming a thicker wall thickness (target 1.20mm) after blowing. The venting grooves on the surface of the trough cavity can quickly discharge the gas between the preform and the cavity, preventing trapped gas from causing surface defects. The zoned cooling channels allow independent control of the cooling rate of different areas. The PLC controller accurately maintains the temperature difference based on the temperature sensor feedback and cools the trough area 3-5 seconds in advance, allowing the trough to solidify and set first, avoiding thinning of the trough when the peak cools and shrinks. This solution achieves stable control of the first peak wall thickness at 1.20±0.2mm, the second to sixth peaks at 1.00±0.2mm, and all troughs at 1.10±0.2mm, with tolerances far superior to the ±0.2mm of traditional blow molding. Pre-cooling of troughs prevents collapse, and no bubbles are found in the airtightness test (immersion in water at 70KPa for 10 minutes). The product expansion is significantly reduced to 1.86mm, far exceeding the 5mm standard.

[0009] Preferably, the local heating element is a heating rod or an annular heating strip; the mold temperature of the first peak cavity is controlled at 180-200℃, and the mold temperature of the remaining peak cavities and trough cavities is controlled at 150-170℃.

[0010] By adopting the above technical solution, the suitable processing temperature for TPEE materials (such as HTR8745) is 200-220℃. Controlling the mold temperature in the first peak region at 180-200℃, close to the melt temperature, significantly reduces the material's flow resistance in this region. Controlling the remaining regions at 150-170℃ ensures moderate melt flow, guaranteeing filling without excessive buildup. A temperature difference of 20-30℃ is a critical range determined through extensive experimentation: when the temperature difference is less than 20℃, the wall thickness difference between the first peak and the remaining peaks is insufficient, failing to achieve effective thickening; when the temperature difference is greater than 30℃, excessive melt flow in the high-temperature zone leads to flash or excessive wall thickness. The heating rod or annular heating strip uses resistance heating, which has advantages over electromagnetic induction coils, such as simple structure, low cost, and stable temperature control. This solution stably achieves a first peak wall thickness of 1.20±0.2mm, and the second to sixth peaks of 1.00±0.2mm, with a temperature control accuracy of ±2℃, no overshoot, and good process repeatability.

[0011] Preferably, the depth of the exhaust groove is 0.05-0.15mm, the width is 1-3mm, and the spacing between adjacent exhaust grooves is 5-10mm; the radial dimension of the first wave-shaped cavity is 0.1-0.3mm larger than that of the other wave-shaped cavities.

[0012] By adopting the above technical solution, a venting groove depth of 0.05-0.15mm can effectively discharge gas without producing flash; a width of 1-3mm ensures venting efficiency; and a spacing of 5-10mm ensures uniform venting. The radial dimension of the first peak cavity is increased by 0.1-0.3mm, pre-reserving more material space structurally, and in conjunction with local heating, further improving the wall thickness control accuracy. This solution leaves no traces of trapped gas on the surface, resulting in a high product appearance qualification rate. The radial dimension difference, combined with heating, further reduces the wall thickness deviation of the first peak.

[0013] A second aspect of this application provides an integral molding process utilizing the aforementioned mold, comprising the following steps: S1: Extruded parison, the parison wall thickness is pre-distributed by adjusting the die gap of the extruder head: the wall thickness corresponding to the first peak is 1.3-1.5mm, the wall thickness corresponding to the remaining peaks is 0.9-1.1mm, and the wall thickness corresponding to the troughs is 1.1-1.3mm. S2: Place the blank in the mold and close the mold; S3: First, introduce compressed air at 0.3-0.6MPa for pre-expansion to allow the preform to initially adhere to the surface of the cavity; S4: Then, compressed air of 1.0-1.8MPa is introduced for high-pressure inflation. At the same time, the PLC controller starts the local heating element to keep the temperature of the first peak area at 180-200℃ and the other areas at 150-170℃ for 10-30 seconds. S5: The PLC controller shuts down the heating element and starts zoned cooling: First, the second cooling circuit is turned on to cool the trough area, and after 3-5 seconds, the first cooling circuit is turned on to cool the peak area. The total cooling time is 20-40 seconds. S6: The mold is opened and the molded part is taken out.

[0014] By adopting the above technical solution, the pre-distribution of the preform wall thickness provides a basic difference, which, combined with mold temperature control, forms a dual regulation; low-pressure pre-expansion prevents premature breakage of the preform, high-pressure expansion ensures detailed replication, and closed-loop pressure control avoids over-expansion; the synergistic effect of zoned cooling sequence and temperature gradient ensures that the troughs solidify and set first, and the peaks solidify later, utilizing the post-shrinkage of the peak material to further compact the troughs and improve sealing. This solution reduces the product expansion to 1.86mm, achieves a pass rate of over 97%, and passes bench tests from -40℃ to 120℃.

[0015] Preferably, during the high-pressure blowing process, the PLC controller adjusts the blowing pressure in real time based on the feedback from the pressure sensor to ensure a smooth process of the parison being molded.

[0016] By adopting the above technical solution, the pressure sensor monitors the internal pressure of the preform in real time, and the PLC controller dynamically adjusts the opening of the air inlet valve through a PID algorithm to keep the inflation pressure stable within the set range, preventing uneven wall thickness or preform cracking due to pressure fluctuations. This solution makes the preform molding process smooth, improves wall thickness consistency by 20%, and reduces the scrap rate to below 2%.

[0017] Preferably, the preform is made of thermoplastic polyester elastomer (TPEE), and the extrusion temperature is controlled at 200-220°C.

[0018] By adopting the above technical solution, TPEE material exhibits excellent high and low temperature resistance (-40℃ to 120℃) and fatigue resistance, which is well matched with the process of this invention. An extrusion temperature of 200-220℃ ensures full plasticization of the material without degradation, resulting in a smooth parison surface and uniform wall thickness. This solution meets the wide-temperature-range durability requirements of the dust cover, and all bench tests were passed.

[0019] The third aspect of this application provides a multi-channel dust cover, manufactured using the aforementioned integral molding process, with the following wall thickness distribution: the first peak wall thickness is 1.20±0.2mm, the remaining peak wall thickness is 1.00±0.2mm, and all trough wall thickness is 1.10±0.2mm.

[0020] By adopting the above technical solution, the non-uniform wall thickness distribution is specifically designed based on the stress distribution law of the dust cover under the large swing angle of the drive shaft: the first peak is located at the small diameter end, bearing the maximum radial force, and thickening it can improve its resistance to deformation; the remaining peaks bear less force, and their thickness is appropriately reduced to reduce weight; all troughs are of equal thickness to ensure coordinated expansion and contraction of the corrugations. This wall thickness distribution results in the dust cover expanding by only 1.86 mm at 80℃ and 1800 r / min, far exceeding the 5 mm standard.

[0021] Preferably, under conditions of 80℃ and 1800r / min, its rotational expansion is ≤1.86mm; it shows no leakage after immersion in water for 10min at 70KPa pressure; and it shows no deformation after standing in water at a depth of 700mm for 30min.

[0022] By adopting the above technical solution, the excellent expansion control stems from the synergistic design of thickened peaks and equal-thickness troughs, combined with high-precision molding processes; the airtightness and water pressure resistance benefit from the surface quality provided by the exhaust channels and the dimensional stability brought by pre-cooling of the troughs. This solution enables the dust cover to meet the most stringent bench specifications of BYD's EQECY project.

[0023] As a preferred embodiment, no cracks or leaks were observed after 20 cycles at a low temperature of -40℃, a swing angle of 18°, and a speed of 1100r / min, and after 240 hours at a high temperature of 120℃, a swing angle of 10°, and a speed of 1200r / min.

[0024] By adopting the above technical solution, the TPEE material itself possesses excellent low-temperature and high-temperature resistance, and the non-uniform wall thickness design avoids stress concentration points, enabling the dust cover to maintain an elastic seal even under extreme temperatures and large sway angles. This solution has passed all bench durability tests, and its service life far exceeds the industry average.

[0025] Preferably, the dust cover is a dust cover for a multi-track drive shaft, and its material is TPEEHTR8745.

[0026] By adopting the above technical solution, HTR8745, a TPEE grade developed by DuPont specifically for automotive bushings, possesses advantages such as high impact resistance, high fatigue resistance, and a low coefficient of friction, making it particularly suitable for high-speed rotating drive shaft seals. This material is perfectly matched to the process of this invention, ensuring stable mass production of the product.

[0027] Compared with the prior art, the present invention has the following unexpected technical effects: 1. Significantly Improved Wall Thickness Control Precision: This invention achieves precise molding of non-uniform wall thickness in multi-channel dust covers, where the first peak is thickened, the remaining peaks are thinner, and the valleys are of equal thickness. The pre-distribution of the preform wall thickness provides the basic difference, while localized mold heating and fixed temperature difference control (the first peak area is 20-30℃ higher than other areas) further amplify the wall thickness difference. Combined with the special design of the first peak cavity radial dimension, this triple synergy ensures stable thickening of the first peak, precise thinning of the remaining peaks, and uniform thickness across all valleys. Compared to traditional uniform wall thickness blow molding processes, this invention significantly reduces wall thickness tolerance, resulting in significantly improved product consistency and repeatability, laying a geometric foundation for subsequent stress distribution optimization and expansion control.

[0028] 2. Significantly Reduced Rotational Expansion: This invention effectively solves the technical challenge of radial expansion of dust covers under high-speed rotation conditions. The thickened first peak enhances the radial stiffness of the small-diameter end (which bears the greatest centrifugal force), effectively resisting deformation caused by centrifugal force; the equal thickness of the troughs ensures coordinated expansion and contraction of the corrugations, avoiding excessive local stretching; and the precise matching of the wall thicknesses of all peaks and troughs ensures balanced overall stress on the dust cover during high-speed rotation, with radial deformation far below industry standard requirements. This effect has not been reported in existing blow-molded dust cover technology and represents a significant advancement.

[0029] 3. Excellent Durability Across a Wide Temperature Range: This invention enables the dust cover to maintain excellent elasticity and sealing performance across a wide temperature range from -40℃ to 120℃. The TPEE material itself has wide temperature adaptability, and the non-uniform wall thickness design avoids stress concentration points—the initial peak is thickened to prevent low-temperature brittleness, while other peaks are appropriately thinned to reduce weight, and the troughs are of equal thickness to ensure coordinated expansion and contraction. Combined with a precise molding process controlled by a PLC closed loop, the dust cover exhibits no cracks or leaks under harsh conditions such as low-temperature large-angle cycling, high-temperature long-term operation, and room-temperature large-angle oscillation, significantly extending its service life.

[0030] 4. Improved Sealing Performance: This invention significantly improves the airtightness and water pressure resistance of the dust cover. The venting groove design on the trough cavity surface effectively eliminates air entrapment defects that easily occur during blow molding, making the trough surface smooth and dense. The zoned cooling sequence control (troughs cool 3-5 seconds first) ensures that the troughs solidify and set first, preventing thinning of the troughs during subsequent cooling and shrinkage of the crests, thus guaranteeing uniform wall thickness and complete sealing of the entire corrugation. The dust cover exhibits stable performance in airtightness and water pressure resistance tests, meeting the most stringent bench specifications.

[0031] 5. Improved Process Robustness and Production Efficiency: This invention significantly improves the stability and adaptability of the blow molding process. The PLC controller, based on real-time feedback from temperature and pressure sensors, uses a closed-loop adjustment system to regulate local heating power, blowing pressure, and cooling sequence, maintaining optimal process parameters and effectively resisting interference from material batch fluctuations and ambient temperature changes. Compared to high-frequency electromagnetic induction, resistive local heating elements offer advantages such as simpler structure, lower cost, and easier maintenance. Furthermore, a fixed temperature difference control strategy is easier to implement and more stable than dynamic temperature control. Therefore, product qualification rates are significantly improved, scrap rates are reduced, and production efficiency is increased, making it suitable for mass industrial production.

[0032] 6. Fundamental Differences from Existing Injection Molding Local Heating Technology: This invention addresses the unique characteristics of blow molding, fundamentally differing from injection molding local heating technologies represented by CN106738737A in several ways: First, the process domains differ: blow molding is used for dust covers on hollow elastomers, while injection molding is used for solid, thin-walled plastic parts. Second, the heating methods differ: resistance-based local heating is more suitable than electromagnetic induction for the long-cycle, large-temperature-difference conditions of blow molding. Third, the temperature control strategies differ: a fixed temperature difference is easier to implement in engineering than dynamic exponential changes. Fourth, it incorporates zoned cooling sequence control, a feature not seen in injection molding technology. These differences bring unexpected technical benefits—for the first time in the blow molding field, high-precision, high-efficiency, and high-stability production of dust covers with non-uniform wall thicknesses has been achieved.

[0033] In summary, this invention, through the synergistic effect of four major features—local heating, fixed temperature difference, zoned cooling sequence, and PLC closed-loop—has achieved for the first time in the field of blow molding the precise, stable, and efficient production of non-uniform wall thickness of multi-channel dust covers, achieving unexpected technical results and demonstrating significant inventiveness. Attached Figure Description

[0034] Figure 1 A schematic diagram of the structure of an integral mold for a multi-channel dust cover provided in this application; Figure 2 A schematic diagram of the structure of the local heating element provided in this application; Figure 3 A schematic diagram showing the fit between the exhaust groove and the first wave crest cavity dimensions provided in this application; Figure 4 This is a schematic diagram of the finished dust cover structure of this application; Figure 5 This is a test diagram of the expansion of the finished dust cover in this application; Figure 6 This is a diagram of the room temperature rotational durability test of the dust cover product of this application; Figure 7 This is a test diagram of the rotating abnormal noise of the finished dust cover of this application; Figure 8This is a diagram showing the airtightness test of the finished dust cover of this application.

[0035] Reference numerals in the attached drawings: 1-Upper mold; 2-Lower mold; 3-Cavity; 4-First peak cavity; 5-Other peak cavities; 6-Valley cavity; 7-Local heating element; 8-Exhaust groove; 9-Sectional cooling channel; 10-First cooling circuit; 11-Second cooling circuit; 12-Temperature sensor; 13-Pressure sensor; 14-PLC controller; 15-Finished dust cover. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1 Reference Figure 1 and Figure 2 The embodiment of this invention provides an integrated molding mold for a multi-channel dust cover, comprising: an upper mold 1 and a lower mold 2. The two can refer to two mating parts that constitute the main body of the mold. Their materials can be mold steel, aluminum alloy or other high-temperature resistant and high-strength metal materials. They are pressed together by a mold closing mechanism to ensure that no overflow or deformation occurs during high-pressure inflation. After the mold is closed, a cavity 3 matching the corrugated shape of the dust cover is formed.

[0038] Cavity 3 exhibits a wave-like undulation in the axial direction, specifically divided into a first peak cavity 4 corresponding to the first peak of the dust cover (usually located at the small diameter end, where the force is greatest), other peak cavities 5 corresponding to the other intermediate peaks, and all valley cavities 6 connecting the peaks; a local heating element 7 is provided circumferentially for the first peak cavity 4, so that the mold temperature of the first peak cavity 4 is controlled at 180-200℃, preferably 180℃ in this embodiment, and the mold temperature of the other peak cavities 5 and valley cavities 6 is controlled at 150-170℃, preferably 160℃ in this embodiment.

[0039] In this embodiment, the aforementioned local heating element 7 is preferably an annular heating strip, which cooperates with the first wave crest cavity 4 to transfer heat to the surface of the first wave crest cavity 4 through thermal conduction, forming a significant temperature difference with other unheated areas. It is a key actuator for achieving non-uniform wall thickness control.

[0040] Reference Figure 3The surface of the trough cavity 6 is provided with venting grooves 8 extending circumferentially. Venting grooves 8 can refer to fine grooves formed on the inner wall of the trough cavity 6. Their depth, width, and spacing can be set according to actual venting requirements; for example, the depth can be 0.1mm and the width can be 2mm. The main function of venting grooves 8 is to quickly expel air between the preform and the cavity 3 during mold closing and initial blow-up, preventing defects such as surface depressions, scorching, or incomplete filling caused by the inability of gas to escape. The circumferential extension of venting grooves 8 ensures uniform venting throughout the trough area. The venting grooves 8, in conjunction with the trough cavity 6, must be designed to ensure venting efficiency while avoiding significant flash, which could affect the product's appearance and sealing performance.

[0041] Reference Figure 1 The mold also includes a partitioned cooling channel 9, including a first cooling circuit 10 corresponding to the first peak area and a second cooling circuit 11 corresponding to the remaining areas; as well as a temperature sensor 12, a pressure sensor 13 and a PLC controller 14; the PLC controller 14 receives signals from the temperature sensor 12 and the pressure sensor 13, and controls the power of the local heating element 7, the inflation pressure and the opening and closing of the valves of the partitioned cooling channel 9, so that the temperature of the first peak area is 20-30°C higher than that of other areas, and the cooling of the trough area starts 3-5 seconds earlier than that of the peak area.

[0042] Valves are installed on the first cooling circuit 10 and the second cooling circuit 11, respectively, and the cooling time of different areas can be independently controlled by opening and closing the valves. The zoned cooling channel 9 works in conjunction with the local heating element 7 to control the curing rate and shrinkage behavior of each area through differentiated cooling sequence, preventing dimensional deviations or thinning of the wall thickness caused by uneven shrinkage.

[0043] Please see Figure 1Temperature sensor 12, pressure sensor 13, and PLC controller 14 together constitute the intelligent control system of the mold. Temperature sensor 12 can be a temperature measuring element such as a thermocouple or resistance temperature detector (RTD), arranged at key temperature control points to monitor the mold temperature in the first peak area and other areas in real time; pressure sensor 13 is used to monitor the internal air pressure during the blowing process. PLC controller 14, as the core processing unit, receives electrical signals from temperature sensor 12 and pressure sensor 13, performs internal logic operations, and outputs control commands. PLC controller 14 is electrically connected to the power module of local heating element 7, the air inlet valve of the blowing system, and the valves of the partitioned cooling channel 9. Through this connection, PLC controller 14 can dynamically adjust the heating power of local heating element 7 to maintain the set temperature difference, adjust the blowing pressure to ensure molding stability, and precisely control the opening and closing time of the valves of the first cooling circuit 10 and the second cooling circuit 11, thereby achieving the process requirements that the temperature of the first peak area is 20-30°C higher than that of other areas and that the cooling of the trough area starts 3-5 seconds earlier than that of the peak area.

[0044] The working process and principle of this embodiment are as follows: During the blow molding process, after the hot melt preform enters the mold and the mold closes, the PLC controller 14 first drives the local heating element 7 to work. The temperature control of the remaining peak cavities 5 and trough cavities 6 also relies on the PLC controller 14 to regulate the overall thermal balance, so that the temperature of the first peak cavity 4 rises rapidly and is maintained at a level 20-30°C higher than other areas. The high temperature reduces the viscosity of the melt in this area, making it easier to flow under blowing pressure and accumulate at the first peak, thereby forming a thicker wall. At the same time, the venting grooves 8 on the surface of the trough cavity 6 quickly discharge the air between the preform and the cavity 3. After the pressure holding is completed, the PLC controller 14, according to the preset program, first turns on the second cooling circuit 11 to cool the trough area. Specifically, it can use the branch channels in the second cooling circuit 11 to solidify and shape the trough first; after a delay of 3-5 seconds, the first cooling circuit 10 is then turned on to cool the first peak area. This sequential design, which involves cooling the troughs first and then the crests, utilizes the additional pressure generated by the material's contraction during cooling at the crest to further compact the solidified troughs. This effectively prevents the troughs from being thinned and ensures the precise forming of structures with non-uniform wall thickness.

[0045] Specifically, the working process and principle of this application are as follows: DuPont HTR8745 grade TPEE material is selected as the raw material, and the extrusion temperature is controlled at 210℃. During the mold closing blow molding process, the PLC controller 14 activates the local heating element 7 (annular heating belt) to rapidly raise the temperature of the first peak cavity 4 to 190℃, while the remaining peak cavities 5 and trough cavities 6 are maintained at 160℃. When the high-temperature preform enters the cavity 3 and compressed air is introduced, the melt in contact with the first peak cavity 4 has a lower viscosity due to the high temperature, making it easier to undergo plastic deformation and material accumulation under pressure; at the same time, the melt in contact with the other areas quickly establishes surface strength due to the relatively lower mold temperature, limiting the disordered flow of the material. This temperature-driven difference in rheological behavior, combined with the subsequent zoned cooling sequence, results in a thicker wall in the first peak area, while the remaining areas maintain a thinner and more uniform wall thickness. This achieves the preset non-uniform wall thickness distribution target. After final cooling and shaping, the wall thickness at this location reaches approximately 1.20 mm, while the wall thickness at the other peaks and troughs is controlled at approximately 1.00 mm and 1.10 mm, respectively, with tolerances within ±0.2 mm. Furthermore, the surface is free of flash and material defects.

[0046] The spacing between adjacent venting grooves 8 can refer to the distance between the center lines of two adjacent venting grooves 8 along the circumference of the trough cavity 6. The value range can be 5mm or 6mm. The spacing determines the uniformity of venting coverage: too large a spacing may lead to poor venting in the area between the two venting grooves 8, forming localized air trapping defects; too small a spacing may weaken the structural strength of the trough cavity 6 or increase processing costs. Venting path: Air is squeezed into the venting grooves 8 by the preform, flows laterally along the venting grooves to the mold parting surface or the venting holes outside the mold, and then is discharged into the atmosphere.

[0047] The radial dimension of the first peak cavity 4 can refer to its theoretical diameter or profile dimension in the radial direction. In this embodiment, the radial dimension of the first peak cavity 4 is designed to be 0.1-0.3 mm larger than the radial dimensions of the other peak cavities 5. This dimensional difference is not a manufacturing error, but a deliberate structural allowance. Since the first peak region bears the greatest radial stress under operating conditions, a thicker wall is required to ensure strength. By increasing the radial space of the first peak cavity 4, and combining this with the high-temperature control of the region by the local heating element 7 (reducing the melt viscosity), more molten material can flow and accumulate within the reserved space. The first peak cavity 4 and the local heating element 7 work together, with the former providing physical space and the latter providing flow dynamics, jointly ensuring that the final formed wall thickness at the first peak is significantly greater than that at the other peaks, thereby achieving precise control of the non-uniform wall thickness.

[0048] Example 2 This embodiment also provides an integral molding process using the aforementioned multi-channel dust cover integral molding mold, including the following steps: Step 1: Extruding the parison. The wall thickness of the parison is pre-distributed by adjusting the die gap of the extruder head: the wall thickness corresponding to the first peak is 1.3 mm, the wall thickness corresponding to the remaining peaks is 1.0 mm, and the wall thickness corresponding to the troughs is 1.2 mm. This step aims to lay the geometric foundation for the non-uniform wall thickness structure of the multi-channel dust cover, ensuring that the first peak has sufficient thickness in the final product to resist centrifugal force at high speeds.

[0049] Step Two: Placing the parison in the mold and closing the mold: The mold closing action is performed by the mold closing mechanism, ensuring a tight seal between the upper and lower molds, forming a closed cavity that perfectly matches the corrugated shape of the dust cover. During the mold closing process, the mold's cutting device simultaneously cuts off both ends of the parison and clamps and seals the parison ends to prevent gas leakage during subsequent inflation. For example, the mold closing pressure is set to 80-100MPa to ensure a seamless parting surface in the mold and that the parison is firmly clamped in the predetermined position. After mold closing, the parison hangs inside the cavity, and its axial wall thickness distribution corresponds one-to-one with the first peak cavity, the remaining peak cavities, and the trough cavities of the cavity. This step completes the sealing of the molding space, creating the necessary sealed environment for subsequent compressed air inflation.

[0050] Step 3: First, pre-inflate the parison with compressed air at 0.3-0.6 MPa to allow it to initially adhere to the cavity surface. Specifically, compressed air is injected into the center of the parison through a blower, and the airflow pushes the parison outward until its surface lightly touches the venting groove area on the inner wall of the mold. For example, if the pre-inflation pressure is set to 0.45 MPa and the holding time is 1-2 seconds, the parison will initially conform to the mold outline in a lantern shape, but it has not yet fully replicated the detailed features of the crests and troughs. The purpose of pre-inflation is to eliminate the large gap between the parison and the mold, preventing local stress concentration and breakage of the parison due to excessive instantaneous impact force during direct high-pressure inflation. It also avoids uncontrollable and severe wrinkling of the parison under high pressure. This step provides a smooth transition for subsequent high-pressure finishing, ensuring the stability of the molding process.

[0051] Step 4: Then, pressurize with 1.0-1.8MPa compressed air for high-pressure inflation. At the same time, the PLC controller activates the local heating element to keep the temperature of the first peak area at about 180-200℃ and the other areas at about 150-170℃, with the temperature difference between the two maintained at 20-30℃ for 10-30 seconds.

[0052] For example, the temperature of the first peak region is set at 190℃, the temperature of the remaining regions at 160℃, the high-pressure blowing pressure is 1.5MPa, and the holding time is 20s. Under these conditions, the high temperature of the first peak region significantly reduces the viscosity of the melt in contact with this region, increasing the material's fluidity. This allows more material to migrate and accumulate at the first peak under high pressure, resulting in a thicker wall. Meanwhile, the lower temperatures in other regions limit excessive material flow, maintaining a thinner wall thickness. The simultaneous high-pressure blowing and localized heating achieve a dual coupling of pressure-driven and thermodynamic control, precisely controlling the wall thickness distribution of the final product. This step is crucial for forming a non-uniform wall thickness structure, directly determining the thickening effect of the first peak and the overall mechanical properties of the product.

[0053] Step 5: The PLC controller shuts down the heating element and starts zoned cooling: First, the second cooling circuit is turned on to cool the remaining areas except for the first peak area. After 3-5 seconds, the first cooling circuit is turned on to cool the first peak area. The total cooling time is 20-40 seconds. In this context, zoned cooling refers to using independently set first and second cooling circuits within the mold to implement differentiated cooling timing control for different areas. After the high-pressure blowing and holding period ends, the PLC controller first cuts off the power to the local heating elements, and then immediately opens the second cooling circuit for the corresponding trough area (and other non-first peak areas), introducing a cooling medium (such as water or oil) for rapid cooling. After a 3-5 second delay, the PLC controller then opens the first cooling circuit for the corresponding first peak area. For example, the second cooling circuit is opened first to cool the trough, and after a 4-second delay, the first cooling circuit is opened to cool the first peak, with a total cooling time set to 30 seconds. The principle of this timing control is that the trough area cools and solidifies first, establishing a stable support framework; subsequently, the first peak area begins to cool and shrink. At this time, the trough has already taken shape, and the subsequent shrinkage of the peak does not produce the negative effect of thinning the trough. Instead, the shrinkage force further compacts the material at the connection between the peak and the trough, increasing density. If cooling occurs simultaneously or the peak cools first, the shrinkage of the peak will pull on the uncured trough, leading to thinning of the trough wall or even the formation of depressions. This step, through precise control over time, effectively prevents trough collapse, ensuring uniform wall thickness and the product's sealing integrity.

[0054] Step Six: Demolding and Removing the Molded Part: This step is performed after the specified cooling time has been completed and the product has fully solidified and set. The PLC controller confirms that the cooling time has reached the set value (e.g., 30 seconds) and the mold temperature has dropped to a safe demolding temperature, then controls the mold closing mechanism to open the upper and lower molds. A robotic arm or ejector removes the molded multi-track dust cover from the cavity and performs trimming to remove excess flash. For example, if the mold opening stroke is 500mm, the robotic arm will clamp and remove the product within 2 seconds of mold opening. The removed molded part has a preset non-uniform wall thickness distribution: the first peak wall thickness is approximately 1.20±0.2mm, the remaining peak wall thickness is approximately 1.00±0.2mm, and the trough wall thickness is approximately 1.10±0.2mm. This step marks the end of a single molding cycle, and the resulting product can directly proceed to subsequent quality inspection or assembly processes.

[0055] This application achieves high-precision one-piece molding of multi-channel dust covers through the synergistic effect of the above-mentioned process steps. Pre-distribution of the preform wall thickness provides an initial material gradient, laying the material foundation for differentiated molding; staged pressure control of pre-blowing and high-pressure blowing avoids preform breakage while ensuring perfect replication of details; local heating and fixed temperature difference strategies utilize the effect of temperature on melt viscosity to actively guide material migration and thickening towards key stress areas (the first peak); and zoned cooling sequence control cleverly utilizes the difference in curing time in different regions, eliminating the thinning defects caused by uneven shrinkage in traditional processes through a mechanism of cooling the troughs first and the peaks later. These interconnected technologies work together to significantly reduce the wall thickness tolerance of the final product, significantly reduce the rotational expansion to below 1.86 mm, and exhibit excellent durability and sealing performance under wide temperature range and large swing angle conditions, meeting stringent automotive parts manufacturing standards.

[0056] Of course, during the high-pressure blowing process, the PLC controller adjusts the blowing pressure in real time based on the feedback from the pressure sensor to ensure a smooth process of the parison being molded. This step can refer to introducing a closed-loop control mechanism based on real-time monitoring data during the high-pressure blowing stage of embodiment S4 described above. Specifically, a pressure sensor, acting as a feedback element, is configured to collect real-time air pressure data inside the preform and transmit analog or digital signals to the PLC controller. The PLC controller has a built-in PID control algorithm or similar dynamic adjustment logic, which compares the received real-time pressure value with a preset target pressure range (i.e., 1.0-1.8 MPa), calculates the deviation value, and outputs control commands accordingly to adjust the opening of the air intake proportional valve. Through this real-time adjustment method, when fluctuations in the preform's internal pressure are detected due to changes in material flow resistance or differences in local die-attaching speed, the system can quickly increase or decrease the air intake to counteract the disturbance and maintain a constant blowing pressure. For example, if the pressure sensor detects a sudden drop in air pressure at the instant the parison rapidly contacts the deep groove area of ​​the cavity, the PLC controller immediately instructs the air inlet valve to increase the opening by 5%-10% to replenish the air supply and maintain pressure stability. Conversely, if the parison completely fits the cavity, causing a sudden decrease in volume and a risk of increased air pressure, the controller fine-tunes the valve to close it to prevent overpressure. This closed-loop pressure control effectively avoids problems such as excessive stretching and thinning of the parison due to pressure overshoot, or even breakage due to insufficient pressure, which are common in traditional open-loop control. This ensures a smooth parison bonding process throughout the high-pressure blowing stage, significantly improving the wall thickness consistency and dimensional accuracy of the final product.

[0057] Example 3 This embodiment provides a multi-channel dust cover finished product 15. The dust cover finished product 15 is manufactured by the integral molding process of the above embodiment 2 through a specific non-uniform wall thickness distribution design. Its wall thickness distribution is as follows: the wall thickness of the first peak is 1.20±0.2mm, the wall thickness of the second to sixth peaks is 1.00±0.2mm, and the wall thickness of all troughs is 1.10±0.2mm.

[0058] The first wave peak wall thickness of 1.20±0.2mm refers to the material thickness at the top of the first corrugated peak near the small-diameter end of the dust cover (usually the end connecting the gearbox or differential). In the structure of this multi-channel dust cover, the first wave peak often bears the greatest radial centrifugal force and axial tensile force; therefore, the wall thickness at this location is configured to be thicker than other wave peaks. This thickness value can be finely adjusted according to the specific drive shaft specifications, speed requirements, and material properties; for example, it can be 1.00mm, 1.20mm, or 1.40mm, etc., and this application embodiment does not impose any special limitation on this. By increasing the wall thickness of the first wave peak, the cross-sectional moment of inertia and radial stiffness of this region can be increased, thereby effectively resisting the centrifugal expansion force generated during high-speed rotation and preventing seal failure due to excessive deformation.

[0059] The wall thickness of the second to sixth peaks is 1.00±0.2mm, which can refer to the material thickness at the tops of the subsequent multiple corrugated peaks distributed along the axial direction of the dust cover, excluding the first peak. These peaks experience relatively smaller radial stresses during vehicle operation compared to the first peak, hence their wall thickness is designed to be thinner. This thickness value can also be set according to actual operating conditions, for example, it could be 0.80mm, 1.00mm, or 1.20mm, etc., and this application does not impose any special limitations on this. Appropriately thinning the wall thickness of the remaining peaks not only helps to reduce the overall weight of the dust cover and decrease rotational inertia, but also improves material utilization while ensuring structural strength, and gives the dust cover better flexibility during oscillation.

[0060] All trough wall thicknesses are 1.10 ± 0.2 mm, which can refer to the material thickness of the recessed area (i.e., the bottom of the corrugation) connecting two adjacent crests. The trough area primarily bears bending deformation during the expansion and contraction of the dust cover. Maintaining uniform wall thickness across all troughs (equal thickness design) is crucial for ensuring coordinated expansion and contraction of the entire dust cover corrugated structure. This thickness value can be set according to design requirements, for example, it can be 0.90 mm, 1.10 mm, or 1.30 mm, etc., and this application does not impose any special limitations on this. Uniform trough wall thickness avoids stress concentration points caused by localized thickness variations, preventing cracks during repeated flexing movements. Combined with specific cooling processes, this ensures the dimensional stability of the trough area, thereby improving the overall airtightness.

[0061] The gyratory expansion of ≤1.86mm at 80℃ and 1800r / min refers to the limiting index for high-temperature and high-speed gyratory performance testing of the multi-channel dust cover manufactured using the aforementioned one-piece molding process. This test condition simulates the harsh operating conditions that the multi-channel drive shaft may encounter in actual vehicle operation, namely, an ambient temperature of 80℃ and a drive shaft speed as high as 1800r / min. Gyratory expansion refers to the maximum radial expansion displacement of the dust cover under centrifugal force. In the technical solution of this application, the thickening treatment of the first peak area (target wall thickness 1.20±0.2mm) and the equal thickness control of the trough area (target wall thickness 1.10±0.2mm) achieved by the preceding process optimizes the overall structural stiffness distribution of the dust cover. The thickened design of the first peak, as the small-diameter end bearing a large centrifugal force, effectively resists radial deformation; while the precise molding of the trough avoids local weak points caused by uneven wall thickness. Therefore, under the aforementioned high temperature and high speed conditions, the rotational expansion of the dust cover can be controlled within 1.86 mm, for example, it can be any value less than or equal to 1.86 mm, such as 1.50 mm, 1.65 mm, or 1.80 mm. This application does not impose any special limitation on this. This indicator reflects the dimensional stability of the dust cover under dynamic rotation conditions, indicating that it can effectively prevent interference or sealing failure caused by excessive expansion.

[0062] The "no leakage" test under 70 kPa pressure for 10 minutes of immersion in water refers to a specified indicator for airtightness testing of dust covers. This test verifies the seal integrity of the dust cover under a certain positive pressure (70 kPa) inside and an external water environment. The 70 kPa pressure value can be set according to actual testing standards or application scenarios, for example, it can be 60 kPa, 70 kPa, or 80 kPa. This application embodiment does not make a special limitation on this. "No leakage" means that no air bubbles are observed escaping from the surface of the dust cover submerged in water within the specified 10-minute test time. This performance is achieved thanks to the preceding mold and process: the venting grooves set on the surface of the trough cavity effectively expel trapped air during the blow molding process, avoiding the generation of surface micropore defects; at the same time, the trough cooling sequence controlled by the partitioned cooling channel (3-5 seconds in advance) allows the trough area to solidify and shape first, preventing the subsequent thinning effect of the trough when the peak cools and shrinks, thereby ensuring the uniformity and density of the wall thickness in the trough area. Therefore, the dust cover can maintain excellent sealing performance under 70 kPa air pressure, meeting the strict requirements for leak prevention.

[0063] The "no deformation after 30 minutes of static pressure testing at a water depth of 700 mm" refers to a specified indicator for the static pressure resistance test of a dust cover. The hydrostatic pressure generated at a water depth of 700 mm is approximately 7 kPa. This test condition is used to evaluate the structural strength and anti-collapse capability of the dust cover under external pressure. "No deformation" means that within the specified 30-minute static period, the dust cover does not exhibit any visible dents, flattening, or permanent shape changes. This technical characteristic is closely related to the reasonable stress distribution formed by the preceding non-uniform wall thickness design (thickening of the first peak, thinning of the remaining peaks, and equal thickness of the valleys). The thickened first peak provides sufficient circumferential stiffness, while the coordinated expansion and contraction of the valley structure ensures the overall stability of the corrugations. The test time of 30 minutes and the water depth of 700 mm are exemplary parameters and can be adjusted to other values ​​according to actual acceptance standards, such as 20 minutes, 40 minutes, or 500 mm, 800 mm, etc. This application embodiment does not specifically limit these values. This indicator shows that the dust cover possesses sufficient structural rigidity to resist external fluid pressure without failure.

[0064] Specifically, the performance of the multi-channel dust cover provided in this application in the above three performance indicators is the result of the synergistic effect of its specific wall thickness distribution and precision molding process. First, based on the preceding process, the pre-distribution of the parison wall thickness is achieved by adjusting the die gap of the extruder head. Combined with localized differential heating of the die (the temperature of the first peak area is 20-30℃ higher than other areas) and zoned cooling sequence control, a non-uniform wall thickness structure is precisely formed, with the first peak being thicker, the remaining peaks thinner, and all troughs of equal thickness. This structure allows the dust cover to effectively resist centrifugal force under high-speed rotation conditions of 80℃ and 1800r / min, by utilizing the thickened small-diameter end (first peak), suppressing the rotational expansion to below 1.86mm. Second, the combination of the venting grooves on the surface of the die trough cavity and the trough-priority cooling strategy eliminates the risk of trapped air during the molding process and prevents the troughs from being thinned, thereby ensuring zero leakage performance of the product in the 70KPa air pressure immersion test. Finally, the overall optimized wall thickness distribution gives the dust cover good overall rigidity, enabling it to maintain its shape stability and prevent deformation under hydrostatic pressure at a water depth of 700mm.

[0065] Specifically, refer to Figure 4 This embodiment uses a multi-channel drive shaft dust cover as the target product. The dust cover has six complete corrugations (six peaks and six troughs), a total length of approximately 102 mm, an inner diameter of approximately 30.5 mm at the small-diameter end, and an inner diameter of approximately 94 mm at the large-diameter end. The designed wall thickness distribution is as follows: first peak (the first peak at the small-diameter end) 1.20 ± 0.2 mm, second to sixth peaks 1.00 ± 0.2 mm, and all troughs 1.10 ± 0.2 mm.

[0066] The material selected is TPEE grade HTR8745. Typical properties of this material are: density 1.20 g / cm³, Shore D45 hardness, tensile strength ≥25 MPa, elongation at break ≥350%, brittle temperature ≤-50℃, and melting point 210℃. Dry at 80℃ for 4 hours before use.

[0067] The product test results are as follows: Wall thickness measurement: Using a coordinate measuring machine (ZEISSCONTURAG2, accuracy ±2μm), four points are taken in the circumferential direction to measure the thickness of each peak and trough, and the average value is taken.

[0068] Reference Figure 5 Expansion test: The dust cover was installed on a functional test bench, and the specified amount of grease was injected. In an 80℃ constant temperature chamber, the rotation speed was increased from 0 to 1800 r / min and maintained for 15 min. The radial expansion at the maximum outer diameter of the dust cover was measured using a laser displacement sensor. Three measurements were repeated, yielding results of 1.84 mm, 1.86 mm, and 1.88 mm, with an average of 1.86 mm.

[0069] Reference Figure 6 Bench durability test: room temperature rotation durability: fixed section swing angle 25°~40°, 600r / min, oscillation frequency 0.5Hz, 150h. After completion, the dust cover showed no cracks and no grease leakage.

[0070] High-temperature rotation: 120℃, swing angle 10°, 1200r / min, 240h. No cracks, no leaks.

[0071] Low-temperature rotation: -40℃, swing angle 18°, 1100r / min, 20 cycles (each cycle: 2h pre-cooling, then 5s start-up, then 15min operation, and finally 60min stationary). No cracks, no leaks.

[0072] Rotational expansion: 80℃, 0-1800r / min, 15min, expansion amount 1.86mm (≤5mm is acceptable).

[0073] Reference Figure 7 Abnormal noise during rotation: 200r / min, outer ball cage 45° swing angle, run for 10 minutes; after water spraying, run for 10 minutes, no abnormal noise was heard.

[0074] Reference Figure 8 Air tightness: When the dust cover and clamp are completely immersed in water, pressurized to 70 kPa and held for 10 minutes, no air bubbles are observed.

[0075] Water pressure resistance: The dust cover contains grease. When placed in water at a depth of 700mm and left to stand for 30 minutes, it shows no deformation or collapse.

[0076] Pass rate statistics: After continuous production of 1000 pieces, 977 pieces passed the appearance inspection and random bench test, with a pass rate of 97.7%. The main reasons for non-compliance were flash (12 pieces) and clamping marks (11 pieces), both of which can be further improved by optimizing the mold parting surface.

[0077] (Temperature difference deviation: Comparison to prove the necessity of ΔT≥20℃) To verify the criticality of the 20-30℃ temperature difference, in other embodiments, the temperature of the first peak region was reduced to 175℃, while the remaining regions were kept at 160℃ (temperature difference of 15℃). All other process parameters were exactly the same. 100 pieces were produced, and 10 pieces were sampled for testing.

[0078] result: The average wall thickness of the first peak is 1.08 mm (target 1.20 mm), while the thickness of the remaining peaks is 1.02-1.04 mm and the thickness of the troughs is 1.08-1.12 mm.

[0079] The difference in wall thickness between the first and second peaks is only 0.04~0.06mm, which does not meet the design requirement of 0.20mm.

[0080] Expansion test: at 80℃ and 1800r / min, the expansion was measured to be 3.25mm (which is still within the ≤5mm standard, but far worse than the 1.86mm in Example 1).

[0081] Low-temperature cycling test: During the 15th cycle, a fine crack appeared at the first peak (due to insufficient wall thickness and stiffness, stress concentration at low temperature).

[0082] Conclusion: When the temperature difference is less than 20℃, the initial peak thickening effect is not significant, failing to meet the design wall thickness requirements, and low-temperature durability decreases. Therefore, limiting the temperature difference ΔT to ≥ 20℃ is a necessary key technical feature of this invention.

[0083] In other embodiments, the partitioned cooling is replaced with synchronous cooling (i.e., the first and second cooling circuits are activated simultaneously), while all other process parameters remain exactly the same. 100 units are produced, and 10 units are sampled for testing.

[0084] Results: Uneven trough wall thickness was observed: the wall thickness of some troughs (especially those near the larger opening) dropped to around 0.95 mm, while the wall thickness of the other trough remained at 1.10 mm.

[0085] Visual inspection: There is a slight depression on the surface of the trough (caused by uneven cooling and contraction).

[0086] Air tightness test: Immersed in water at 70 kPa for 10 min, 3 samples showed trace bubbles (leakage rate 3%).

[0087] Expansion test: 1.95mm.

[0088] Conclusion: When the troughs and crests cool simultaneously, the troughs are thinned by the contraction of the crests before they are fully solidified, leading to uneven wall thickness and reduced sealing performance. Therefore, limiting the cooling of the trough region to 3-5 seconds earlier than the crest region is a necessary key technical feature of this invention.

[0089] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A one-piece molding mold for a multi-channel dust cover, characterized in that, include: The upper mold and lower mold, after being closed, form a cavity that matches the corrugated shape of the dust cover; the cavity includes a first peak cavity corresponding to the first peak of the dust cover, the remaining peak cavities, and all the trough cavities; The first wave crest cavity is provided with a local heating element in the circumferential direction; The surface of the trough-shaped cavity is provided with venting grooves extending circumferentially; The mold also includes partitioned cooling channels, including a first cooling circuit corresponding to the first wave crest region and a second cooling circuit corresponding to the remaining regions; In addition, temperature sensors, pressure sensors, and PLC controllers; The PLC controller receives signals from the temperature sensor and pressure sensor, and controls the power of the local heating element, the inflation pressure, and the opening and closing of the valves of the partitioned cooling channel, so that the surface temperature of the mold cavity in the first peak area is 20-30°C higher than that in other areas, and the cooling of the trough area starts 3-5 seconds earlier than that of the peak area.

2. The mold according to claim 1, characterized in that, The local heating element is an electric heating rod or an annular heating strip; the mold temperature of the first peak cavity is controlled at 180-200℃, and the mold temperature of the remaining peak cavities and trough cavities is controlled at 150-170℃.

3. The mold according to claim 1, characterized in that, The exhaust groove has a depth of 0.05-0.15mm, a width of 1-3mm, and a spacing of 5-10mm between adjacent exhaust grooves; the diameter of the first wave crest cavity is 0.1-0.3mm larger than the other wave crest cavities.

4. An integral molding process using the mold according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Extruded parison, the parison wall thickness is pre-distributed by adjusting the die gap of the extruder head: the wall thickness corresponding to the first peak is 1.3-1.5mm, the wall thickness corresponding to the remaining peaks is 0.9-1.1mm, and the wall thickness corresponding to the troughs is 1.1-1.3mm. S2: Place the blank in the mold and close the mold; S3: First, introduce compressed air at 0.3-0.6MPa for pre-expansion to allow the preform to initially adhere to the surface of the cavity; S4: Then, compressed air of 1.0-1.8MPa is introduced for high-pressure inflation. At the same time, the PLC controller starts the local heating element to keep the temperature of the first peak area at 180-200℃ and the other areas at 150-170℃ for 10-30 seconds. S5: The PLC controller shuts down the heating element and starts zoned cooling: First, the second cooling circuit is turned on to cool the remaining areas except for the first peak area. The trough area is cooled first in the cooling sequence of all peak areas. After solidification for 3-5 seconds, the first cooling circuit is turned on to cool the first peak area. S6: Open the mold and remove the molded part.

5. The process according to claim 4, characterized in that, During the high-pressure blowing process, the PLC controller adjusts the blowing pressure in real time based on the feedback from the pressure sensor to ensure a smooth process of the parison being molded.

6. The process according to claim 4, characterized in that, The preform is made of thermoplastic polyester elastomer (TPEE), and the extrusion temperature is controlled at 200-220℃.

7. A multi-channel dust cover, characterized in that, Manufactured using the integral molding process described in any one of claims 4 to 6, the wall thickness distribution is as follows: the wall thickness of the first peak is 1.20±0.2mm, the wall thickness of the remaining peaks is 1.00±0.2mm, and the wall thickness of all troughs is 1.10±0.2mm.

8. The multi-channel dust cover according to claim 7, characterized in that, Under conditions of 80℃ and 1800r / min, its rotational expansion is ≤1.86mm; it shows no leakage after immersion in water for 10min at 70KPa pressure and no deformation after standing in water at a depth of 700mm for 30min.

9. The multi-channel dust cover according to claim 7, characterized in that, No cracks or leaks were observed after 20 cycles at -40℃, 18° swing angle, and 1100 r / min, and after 240 hours at 120℃, 10° swing angle, and 1200 r / min.

10. The multi-channel dust cover according to claim 7, characterized in that, The dust cover is a dust cover for a multi-track drive shaft, and its material is HTR8745.

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